Additional Articles

Series Arrangement Technique for Highly-Directive PCB Leaky-Wave Antennas With Application to RFID UHF Frequency Scanning Systems
06 September 2024 Miguel Poveda-García, Alejandro Gil-Martínez, Astrid Algaba-Brazález, David Cañete-Rebenaque and José Luis Gómez-Tornero propose the efficient series connection of planar leaky-wave antennas (LWA) to obtain directive frequency beam scanning. Conditions for the proper performance are here derived, showing that the distance between antennas must be minimized while optimizing the phase shift introduced by the interconnection. Consequently, the methodology to design the transition is presented by an example using SMA connectors and a meander coaxial cable. Such series arrangement is useful to overcome the restricted directivity of planar LWAs in the UHF band due to limited PCB standard manufacturing sizes, while optimizing the radiation efficiency. The presented theory is validated with practical design examples of microstrip LWA arrays operating in the 900 MHz UHF band.
Ascertaining Operating Points of Harmonic Transponders Using Intermodulation Responses
16 August 2024 Jeff Frolik, Elsie Anthonio, Rye Fought and Tara Harte propose leveraging the harmonic transponders’ nonlinearity by interrogating with two closely spaced signals and then measuring the second harmonics and nearby second and fourth intermodulation distortion products. The results show that it is able to remotely determine the power incident at the device, over a 25 dB range and within ±1 dB, using only the relative ratios between these received components. This result has applications in characterizing the loss of unknown channels and in conducting over-the-air characterization of fully integrated transponders.
Adaptive Radio Frequency Sensor Enabled by Electromechanically Controlled Stretchable Rectifying Antenna Systems
06 August 2024 Zebin Zhu, Bingyang Li, Yajiao Ke, Yuchao Wang, Zequn Wang, Shihao Sun, Ping Lu, Furong Yang, Chaoyun Song, Hongxing Dong, Long Zhang and Cheng Zhang propose a low-cost, substantially simplified solution utilizing a stretchable rectenna, a microcontroller unit (MCU), and feedback control systems to overcome the high costs of high-performance spectrum analyzers and RF signal analyzers in radio frequency detection or ambient spectrum sensing. By exploiting the dynamic correlation between the resonant frequency and the tensile ratio of the stretchable antenna, the incoming frequency can be determined by recording the maximum rectifier DC power output as a function of the electromechanically controlled tension ratio of the stretchable antenna.
Contactless Moisture Content Sensor Based on Wheeler Cap for Waste-to-Energy Plants
01 August 2024 Prakorn Pratoomma, Adam Narbudowicz and Suramate Chalermwisutkul presents a novel nondestructive, contactless moisture content sensor based on the Wheeler Cap measurement technique. The sensor comprises an electrically small antenna enclosed within a compact metallic cap, along with the material under test. The operating frequency of the sensor without material under test is 268.25 megahertz. By measuring the reflection coefficient at the input port of the antenna enclosed in the metallic cap, the moisture content of the material under test can be determined. The proposed sensor is aimed for moisture content measurement of the municipal solid waste, the primary feedstock for refuse-derived fuel utilized in waste-to-energy power plants.
Preliminary Design and Test of a Microwave Inline Moisture Sensor for the Carasau Bread Industry
18 July 2024Giacomo Muntoni, Matteo B. Lodi, Alessandro Fedeli, Andrea Melis, Claudia Macciò, Matteo Pastorino, Andrea Randazzo, Giuseppe Mazzarella and Alessandro Fanti present the design and validation of a methodology for the water content estimation in the Carasau bread manufacturing process, within the framework of the recent agri-food technological advancement. Within the framework of the recent agri-food technological advancement, following a thorough evaluation of the dough dielectric properties, a suitable antenna layout has been selected, pointing out the advantages in the choice of a contactless narrow-band antenna in comparison to wide-band and dual-band ones. The presented simulated results are then validated using a prototype sensor and an ad hoc measurement system to confirm the antenna ability to discriminate among doughs with different water content.
A State-of-the-Art Survey on Advanced Electromagnetic Design: A Machine-Learning Perspective
11 June 2024 Masoud Salmani Arani, Reza Shahidi and Lihong Zhang present an overview of recent developments in optimization and design automation techniques for EM-component design and modeling. Limitations of conventional optimization methods are discussed, while the need for novel machine learning techniques capable of handling multiple objectives and large design spaces is highlighted. In this study, existing methods in the literature are reviewed from four viewpoints: structural view, algorithm view, component view, and application view. Different schemes in distinct design stages or applications are examined with advantages and drawbacks laid out for easier comprehension.
An Improved Uniaxial Perfectly Matched Layer Based on Finite Element Method for Hyperbolic Media
11 June 2024 Na Liu, Yansheng Gong, Rui Xu, Huanyang Chen and Guoxiong Cai analyze the reason for the failure of uniaxial perfectly matched layer (UPML) in absorbing electromagnetic waves with hyperbolic media (HM). They also propose an improved UPML based on the frequency domain finite element method (FEM) to truncate the unbound hyperbolic computational domain. Finally, the excellent absorption effect of the improved UPML is verified by representative examples such as an infinite HM, a linear-crossing metamaterial, and a Bessel beam.
Wideband and High-Efficiency Circularly Polarized Unit-Cell for X and Ka-Band Transmitarrays
10 June 2024 Alessandro de Oliveira Cabral Junior, Hamza Kaouach and André Barka present a novel approach for linear to circular polarization (LP-CP) conversion in transmitarray antennas. The proposed conversion mechanism differs significantly from previous published realizations. The concept utilizes a transmission line modeling-based excitation technique, in which a centralized via excitation is split into two striplines carefully designed to balance excitations and guarantee a phase quadrature. The striplines are embedded at the center of the patch antenna allowing a compact footprint and a simple design structure. The applied true-time delay (TTD) technique assures the radiation of a wideband and low axial ratio circularly polarized (CP) field.
Multibeam Compact Reflectarray Antenna With Low Scan Loss and Wide-Angle Performance Using a Multi-Feed Configuration
06 June 2024 Andrés Gómez-Álvarez, Álvaro F. Vaquero, Manuel Arrebola and Marcos Rodriguez Pino present two multibeam reflectarray antennas for Ka-band in a multi-feed configuration. Both feature a wide-angle scanning range with very low scan losses. They are designed using an iterative optimization process based on a phase-only optimization (POO) which allows fine control over the gain for each beam. The phase responses of the lattice cells are selected taking into account the illumination levels and radiation requirements of all feeds in the system. Minimization of scanning losses and overall antenna compactness are prioritized in the design. The feeding elements are placed along a tilted arc with a low F/D of 0.58. Compared to other beam scanning reflectarray designs in the literature, inter-feed blockage is avoided and thus simultaneous multibeam operation is supported.
Gain Enhancement and Sidelobe Level Reduction of Microstrip Patch Antenna Under Operation of TM50-Like Mode
31 May 2024 Renan A. Santos, Helton S. Bernardo, Danilo H. Spadoti, Guilherme S. da Rosa and Rafael A. Penchel propose a microstrip patch antenna (MPA) operating in the TM50-like mode, designed for gain enhanced and sidelobe levels (SLLs) reduction. The methodology involves altering the resonator’s surface current distribution by introducing three groups of transverse slots at points of null electric field. Additionally, two symmetrically positioned stubs are utilized to the antenna’s gain enhanced. They verify that proper combinations of such artifacts on the proposed radiators significantly reduce the SLL while maintaining the high-gain characteristics of the TM50-like mode. A prototype was fabricated and characterized for operation around 7.6 GHz, in the C band.
Electromagnetic-Informed Generative Models for Passive RF Sensing and Perception of Body Motions
30 May 2024Stefano Savazzi, Federica Fieramosca, Sanaz Kianoush, Michele D’Amico and Vittorio Rampa discuss two popular techniques, namely Variational Auto-Encoders (VAEs) and Generative Adversarial Networks (GANs), and their adaptations to incorporate relevant electromagnetic (EM) body diffraction methods. The proposed EM-informed GNN models are verified against classical EM tools driven by diffraction theory, and validated on real data. The paper explores emerging opportunities of GNN tools targeting real-time passive RF sensing in communication systems with dense antenna arrays. Proposed tools are also designed, implemented, and verified on resource constrained wireless devices.
Beamforming of Transmit Antennas Using Grey Wolf Optimization and L2-Norm for Performance Enhancement of Beyond 5G Communications
29 May 2024Samar I. Farghaly, Mostafa M. Fouda and Manal M. Emara proposes a new beamforming strategy based on a hybrid combination between grey wolf optimizer (GWO) with L2 -norm called proposed GWO. This approach is applied to synthesized uniform linear arrays (ULA), Chebyshav arrays, and shaped pattern arrays. Moreover, it is utilized for side lobe level (SLL) and size reduction of antenna elements. In this strategy, the GWO is utilized to optimize the element spacing to adjust the half-power beamwidth (HPBW) to save it the same as desired pattern. Furthermore, the excitations of the antenna elements are optimized via the L2 -norm minimization problem. The proposed GWO has low complexity (fewer iterations and computing time) compared to other algorithms.
A Mutual Coupling-Based Full Self-Online Calibration Method for Antenna Arrays in Uplink
28 May 2024 Aral Ertug Zorkun, Miguel A. Salas-Natera, Alvaro Araujo Pinto, Ramón Martínez Rodríguez-Osorio and Manuel Sierra Pérez propose a mutual coupling based self-calibration method for transmit mode large scale antenna arrays. In accord with the proposed active antenna array model, gain/phase uncertainties, antenna element position errors and mutual coupling effects are reduced to an error matrix. The expansion of equations of the proposed calibration method are presented. The proposed calibration procedure is capable of compensating the error matrix while the system is operating and is suitable for off-line, on-site and online calibration procedures.
Design of a Dual-Band Planar Sleeve Monopole Antenna With the Substrate-Integrated Coaxial Line Technology
28 May 2024 Ying C. Zheng, L. Zhu, C. Ni, J. Ding, K. Cao and B. Liu propose a dual-band sleeve monopole antenna with the substrate-integrated coaxial line (SICL) technology. Both the radiation structure and the feeding network are modified from the SICL structure. The antenna provides dual-band operation for LoRa (Long Range Radio) applications covering 433 MHz and 868 MHz bands. This antenna operates as a quarter-wavelength monopole with practical omnidirectional radiation performance for each band. The antenna exhibits a gain of 2.0 dBi at 433 MHz with more than 90% radiation efficiency, and a gain of 1.7 dBi at 868 MHz with more than 90% radiation efficiency.
Design Guidelines and Performance Analysis of a Wideband Coaxial Horn Antenna Fabricated via Additive Manufacturing
27 May 2024 Elígia Simionato, Ivan Aldaya, José A. de Oliveira, Andre L. Jardini, Julian Avila, Guilherme S. da Rosa and Rafael A. Penchel introduce a Ka-band coaxial horn antenna that incorporates a specialized dielectric supporting structure and a transition to a 2.4 mm connector. The inner and outer radii of the coaxial aperture were sized using an approximated model for an open-ended coaxial waveguide. The theory of small reflections was then used to account for the reflection coefficient resulting from an additional cascading cylindrical-conical section. A refined numerical model, representing more accurately a prototype, featured a transition region to standardized connectors and a dielectric structure that offers mechanical support for the inner conductor and impedance matching.
RF Circuit Analysis of UWB Planar Log Periodic Antenna for 5G Communications Using Theory of Characteristic Modes
08 May 2024 P. Sumithra, Mohammed Gulam Nabi Alsath, K. J. Jegadishkumar and D. Kannadassan present the systematic RF analysis, fabrication, and equivalent circuit modeling for sub-6GHz 5G application using theory of characteristic modes (TCM). The fabricated pLPA is designed to cover the 5G bands with a high gain of >5 dBi and a fractional bandwidth of >1. Using simulation tool based on method of moments, radiating and non-radiating modes are tracked and studied with detailed physics. These modes are modeled using analytically derived equivalent circuit and assembled in an RF/microwave circuit simulator.
Refinements to the Design of Traveling-Wave Waveguide Slot Arrays
03 May 2024 Jacob C. Coetzee presents a new design approach to traveling-wave waveguide slot arrays that not only ensures that sidelobes specifications are met, but also achieves good impedance matching and high efficiency. The procedure is demonstrated using a 21-element array in standard X-band waveguide and performance is validated though both simulation and measurement.
Ultra-Wideband Phased Antenna Array Time Delay Unit Architecture Optimization in Presence of Component Non-Idealities
01 May 2024 Daniel A. Ramirez, W. Joel D. Johnson and Gokhan Mumcu investigate the recently reported time delay unit architecture (TDU-A) optimization method based on integer linear programming for practical implementation of ultra-wideband (UWB) phased antenna arrays (PAAs). Specifically, the method is considered for linear UWB PAAs and their feed networks which include non-idealities when practical implementations of their circuit components are pursued. These non-idealities are shown to cause additional time delay errors that were unaccounted for in prior work. The errors are induced by frequency dependent variations in power divider isolation and load mismatch, component VSWRs, and dispersion.
Point Cloud-Based Prediction Models of Dynamic Human Body Shadowing at 58 GHz
29 April 2024 Chechia Kang, Xin Du and Jun-Ichi Takada propose screen models and an elliptic cylinder model based on the instantaneous point clouds (PC) of human geometry for the human body shadowing (HBS) channel simulation using the uniform theory of diffraction (UTD). The proposals enable fair evaluation via a simultaneous measurement of the HBS channel and the PC. The HBS gains at the 58 GHz band in an indoor environment (6.5 m) between the measured and the simulated results based on the proposed models are compared.
Experimental Phase-Encoded Linear Sampling Method Imaging With a Single Transmitter and Receiver
25 April 2024 Matthew J. Burfeindt, Hatim F. Alqadah and Scott Ziegler evaluate the phase-encoded linear sampling method (PE-LSM) using experimental data. They collect synthetic aperture data in an anechoic chamber using only a single transmit-receive channel. With the aid of a monostatic-to-multistatic transform, they generate reconstructions of each target via the PE-LSM. The results evince significant improvements in fidelity to the true target geometries compared to imagery generated by both conventional LSM processing and a conventional backprojection-based radar approach.
Wi-Fi-Based Human Activity Recognition for Continuous, Whole-Room Monitoring of Motor Functions in Parkinson’s Disease
24 April 2024 Shih-Yuan Chen and Chi-Lun Lin proposes a novel approach for human activity recognition using Wi-Fi signals. Traditional methods for signal processing are avoided by converting the ratio of channel state information from antenna pairs into images. These images are then processed using a convolutional neural network to detect movements related to diseases in a large dataset. The experiments utilize a laptop PC with Intel Wi-Fi Link 5300 and a receiver equipped with three external 12 dB omnidirectional antennas in the 2.4 GHz band and cover various daily activities. The proposed method has demonstrated remarkable accuracy, with an average recognition rate of 93.8% in validation. It also showcased a consistent accuracy range of 91.9% to 95.2% in generalization tests, proving its effectiveness in different environments, with various individuals, and under assorted Wi-Fi configurations.
Fully Embedded Dual-Element Dielectric-Based Antenna for Sub- and Terahertz Applications
23 April 2024 Ehsan Rahmati, Pascal Burasa, Elham Baladi and Mohammad S. Sharawi present a completely embedded, planar, dual-element dielectric based antenna directly fed by a substrate integrated insulated guide within the same layer in Sub-THz band. A dielectric layer is employed to make the structure stable. The proposed structure is compatible with the standard planar millimeter-wave and terahertz manufacturing technologies. To minimize the reflection loss, matching air holes inside the guiding channel of the waveguide and air holes with a smaller perforation radius surrounding the antenna are created. The proposed compact antenna, which has been successfully tested, covers the frequency range of 234.5-278.1 GHz with a measured impedance bandwidth of 17.01%, a proper simulated average radiation efficiency of 93.6%, and a maximum gain as well as average gain of 16.08 dBi and 12.56 dBi from measurement results, respectively.
Synthesis and Design of 3-D Microwave Absorber With 70° Angular Stability for C-Band and X-Band
22 April 2024 Tian-Xi Feng, Lei Zhu and Hui Li present the synthesis and design of 3-D microwave absorber with 70° angular stability for C-band and X-band. The operating principle is firstly investigated, where the absorber is considered as an energy convertor. With the help of our proposed universal equivalent transmission line (TL) model, the absorptive performance can be accordingly synthesized. Then, a design method for efficient absorption under large angles is presented. By selecting a proper synthesized angle (SA), the angular stability can be effectively improved.
Channel Measurements at 300 GHz for Low Terahertz Links in a Data Center
22 April 2024 Johannes M. Eckhardt, Tobias Doeker and Thomas Kürner present comprehensive double-directional channel measurements with time-domain channel sounding at 300 GHz that characterize the channel of wireless links in a data center. The channels are classified into three scenario-dependent use cases and are individually analyzed providing channel parameters as a function of the required signal-to-noise ratio of the prospective communication system. The spatial and temporal analysis of the channel reveals relevant propagation effects such as the influence of scattering and derives relations between the channel parameters of the propagation and the radio channel.
Wireless Power Transfer for Implantable Medical Devices: Impact of Implantable Antennas on Energy Harvesting
22 April 2024Amine Essa, Eqab Almajali, Soliman Mahmoud, Rony E. Amaya, Saqer S. Alja’Afreh and Muhammad Ikram present a thorough review of the main techniques used for wireless power transfer (WPT) in implantable medical devices (IMDs) with a specific focus on the techniques that employ implantable antennas for energy harvesting (electromagnetic (EM) WPT techniques). The techniques are first analysed and compared based on the IMD application, power transfer efficiency (PTE), transfer distance, implantation depth, implant size, operating frequency, and specific absorption rate (SAR). The study provides a critical analysis of the main WPT system’s as well as implantable antennas’ design parameters that control the PTE and hence the charging rate of the IMD. The investigated design parameters include the WPT TX-RX antennas’ gain, WPT-RX size, transfer distance, and the WPT TX-RX antennas’ alignment.
A Machine Learning Approach to Wireless Propagation Modeling in Industrial Environment
22 April 2024 Mohammad Hossein Zadeh, Marina Barbiroli and Franco Fuschini harnesses the power of Machine Learning to model propagation markers like path loss, shadowing, and delay spread in the industrial environment in this article. By employing Machine Learning techniques, the objective is to achieve flexibility and adaptability in modeling, enabling the system to effectively generalize across diverse industrial scenarios. The proposed model relies on a combination of predictive algorithms, including a linear regression model and a Multi-Layer Perceptron, working collaboratively to model the relationship between the considered propagation markers and input features like frequency and machine size, spacing, and density. Results are in fair overall agreement with previous studies and highlight some trends about the sensitivity of the propagation parameters to the considered input features.
Energy Autonomous Dual-Band Antenna System for RFID-Based Real-Time Battery Level Monitoring
10 April 2024 Braden P. Smyth, Hamed Khoshniyat, Mahdi Barati, Samuel Clark, Rashid Mirzavand and Ashwin K. Iyer presents an energy-autonomous antenna system that combines energy harvesting (EH) with radio frequency identification (RFID) communication to measure the battery charge level in real time. The system employs a dual-band patch antenna, a dual-band matching stub, and a diplexer, which are designed with metamaterial-based electromagnetic bandgap technology (MTM-EBG). Due to the MTM-EBG’s uniplanar and via-less design, it can be directly embedded into the antenna and microstrip feed components, thereby contributing to their compactness, lowering cost, and simplifying fabrication.
60 GHz Programmable Dynamic Metasurface Antenna (DMA) for Next-Generation Communication, Sensing, and Imaging Applications: From Concept to Prototype
10 April 2024 Abdul Jabbar, Mostafa Elsayed, Jalil Ur Rehman Kazim, Zhibo Pang, Julien Le Kernec, Muhammad Ali Imran, Qammer H. Abbasi and Masood Ur-Rehman present the complete design of a dynamic metasurface antenna (DMA) array at the 60 GHz millimeter-wave (mmWave) industrial, scientific, and medical (ISM) band. First, a novel complementary electric inductive-capacitive (CELC) metamaterial element (unlike conventional rectangular CELC) is designed to resonate around 60.5 GHz. The proposed CELC meta-element in its resonance state manifests dispersive characteristics and exhibits significant left-handed metamaterial properties such as negative group refractive index, negative effective permittivity, and negative group velocity, which are thoroughly elucidated.
RF-MEMS Switch for Reconfigurable With Half-Moon Slots on Elliptical-Shaped Patch Antenna for 5G Applications
10 April 2024 Ketavath Kumar Naik and Bokkisam Venkata Sai Sailaja design a compact dual-band reconfigurable elliptical-shaped patch antenna. The proposed patch antenna with rectangular strip lines and an elliptical with half-moon slots presented to operate dual bands. To achieve the reconfigurability, RF-MEMS switches proposed on rectangular strip lines of the patch antenna. The capacitive shunt type RF-switch designed the proposed elliptical antenna to operate at 5G applications. The displacement of the proposed RF-MEMS switch with an air gap of 3 μ m, the actuation of 5.02 V, and the stress of the proposed beam is bearable up to 85.7 MPa is observed. The reconfigurable elliptical-shaped patch antenna resonates at 8.34 GHz and 10.47 GHz with a reflection coefficient of −32.28 dB and −22.7 dB respectively.
Application of Machine Learning-Assisted Global Optimization for Improvement in Design and Performance of Open Resonant Cavity Antenna
04 April 2024 Koushik Dutta, Mobayode O. Akinsolu, Puneet Kumar Mishra, Bo Liu and Debatosh Guha explore machine learning (ML)-assisted antenna design techniques aiming to improve and optimize its major radiation parameters over the maximum achievable operating bandwidth. A state-of-the-art method, e.g., parallel surrogate model-assisted hybrid differential evolution for antenna synthesis (PSADEA) has been exercised upon a reference ORCA geometry revealing a fascinating outcome. This modifies the shape of the cavity which was not predicted by EM-based analysis as well as promising significant improvement in its radiation properties.
Integrated Solar Panel Slot Antennas Certified for CubeSat Missions
04 April 2024 Mahmoud N. Mahmoud and Reyhan Baktur present three prototypes of cavity-backed slot antennas integrated with solar panels. The antenna design is straightforward and requires minimal alteration on the solar panel’s geometry. The antennas and solar cells are on the same surface and are effectively independent of each other. This eliminates the need for custom designed solar cells required in previous studies. The integrated solar panel antennas were demonstrated using all commercial-off-the-shelf space-qualified components and printed circuit board technology.
A Compact Dual-Band Tripolarized Patch Antenna With Simple Structure and Very High Isolation
01 April 2024 Son Xuat Ta, Tran Hien Bui, Khac Kiem Nguyen and Nghia Nguyen-Trong present a compact dual-band tripolarized antenna with simple structure and high isolation operating at 2.45 GHz and 3.5 GHz bands. The design is composed of a slotted patch and a monopolar patch connected together by four vias. The antenna uses a double differential-fed scheme for x- and y-horizontally polarized broadside radiations and a single-ended port at the center for vertically-polarized omnidirectional radiation. The combination of slotted patch, monopolar patch, and vias yields several interesting features, which are exploited in the design to achieve dual-band tripolarized operation.
Miniaturized Design of Dual Transmission Frequency Selective Rasorber With Wide Angular Stability
28 March 2024 Mehran Manzoor Zargar, Archana Rajput and Kushmanda Saurav propose a miniaturized design of dual transmission frequency selective rasorber (FSR) with absorption-transmission-absorption-transmission (A-T-A-T) feature. Initially, low frequency resonators are incorporated on the square ring shaped lossy resistive layer for expanding the broad absorption towards the lower spectrum of frequency. Then the dual bandpass frequency selective surface (FSS) with transmission bands lying within the absorption spectrum is integrated with the resistive layer. Further, a cross-loop resonator is integrated inside the square ring of the resistive layer due to which a dual transmission pole is achieved through the resistive layer aligning with the dual operating frequencies of bandpass FSS.
Synthesis of Reactively Loaded Sparse Antenna Arrays Using Optimization on Riemannian Manifold
28 March 2024 Albert Salmi, Anu Lehtovuori and Ville Viikari introduce a method for computing reactive terminations for scatterer elements in antenna arrays. With the fixed scatterer elements, they shape embedded element patterns of sparse arrays to focus the radiation into a grating-lobe-free limited field of view. The reactive terminations of the scatterer elements are determined by optimizing reflection coefficients on a Riemannian manifold. In addition, they show that widening the grating-lobe-free field of view is possible by tilting the field of view. They design both 5-element linear and 4-by-4-element planar reactively loaded antenna arrays with 1.4-wavelength inter-element distances.
Investigation of a Circularly Polarized Log-Periodic Dipole Antenna
20 March 2024 Kunpeng Wei, Xiaopeng Zhang, Libin Sun and Changjiang Deng investigate a circularly-polarized (CP) log-periodic dipole antenna (LPDA). Eight crossed dipole cells with a logarithmically increased λ /8 separation are employed to form the proposed CP LPDA. The dipoles with increased length and spacing are fed in series by an air-filled parallel line. The working mechanism of the generation of back-fire CP radiation is illustrated by an array analyzation. Besides, the LPDA design factors for both polarizations are analyzed in detail to realize an optimized CP performance.
Effects and Models of Offset-Via in Electromagnetic Band Gap Structure
20 March 2024 Luohao Liu, Fan Yang, Shenheng Xu and Maokun Li investigates the effects of the via in a mushroom-like EBG structure and propose an equivalent circuit model of the via. It is revealed that when the via in the mushroom-like structure is offset, the element reflection phase will vary within 720 degrees instead of 360 degrees phase range in a conventional design. This phenomenon can be explained by a new circuit model that introduces a mutual inductance, and the corresponding electromagnetic properties of mushroom-like EBG structure can be quantitatively analyzed by this model.
Frequency-Diverse Reflection Metasurface Antenna Design for Computational Microwave Imaging
18 March 2024 Aobo Li, Mengran Zhao, Dónal Patrick Lynch, Shitao Zhu, Muhammad Ali Babar Abbasi and Okan Yurduseven propose the design of a computational microwave imaging (CMI) oriented frequency-diverse reflection metasurface antenna (FDRMA). Designing a FDRMA for CMI requires a careful synthesis framework, from the topology of metamaterial elements to the statistical analyses of the metasurface and the evaluation of its CMI performance. Consequently, they begin with an investigation of different metamaterial element topologies with the aim to choose the optimal one to constitute a desired reflection metasurface. The FDRMA is then designed by randomly distributing the metamaterial elements with diverse structural parameters. The orthogonality of the reflected field patterns is investigated by means of a spatial-correlation evaluation and a singular value decomposition.
Modeling of the Fault Detection Problem for a 3-D Hybrid Antenna Array: Analysis and Evaluation
18 March 2024 Somayeh Komeylian and Christopher Paolini implement the ADMM method under the joint sparsity setting to solve the regularized l_2,1-norm problem for a number of samples of the degraded radiation pattern of the HAAwBE rather than computing its array factor, which requires significant and complex mathematical computation. The proposed ADMM technique under the joint sparsity setting allows for minimizing the cost function of the problem with respect to both model parameters and variable vectors. They have further increased accuracy and stability of the performance of the HAAwBE in the two problems of fault detection and DoA estimation by deploying three different optimization methods: LS-SVM, NN-RBF, and NN-MLP, and compared to each other.
Low-Profile CO-CSRR and EBG Loaded Tri-Quarter Circular Patch EWB MIMO Antenna With Multiple Notch Bands
18 March 2024 Hemalatha T and Bappadittya Roy develop and simulate a novel and miniaturized design featuring a Co-directional Complementary Split Ring Resonator (CO-CSRR) loaded Tri-Quarter Circular (TQC) Extremely Wideband (EWB) Multiple-Input Multiple-Output (MIMO) antenna. This proposed antenna demonstrates high isolation and exhibits multiple notch characteristics. The configuration consists of two TQC patches positioned adjacent to each other with a common partial ground plane (PGP), achieving an Extremely Wideband (EWB) capability of 85.8 GHz.
A Single-Antenna Full-Duplex Subsystem With High Isolation and High Gain
18 March 2024 Li Zhang, Miao Lv, Zhi-Ya Zhang, Yu Wang, Fanchao Zeng, Can Ding and Chenhui Dai propose a single-antenna full-duplex subsystem, consisting of a high isolation network and a stacked patch antenna with reflector. The employed patch antenna is fed by two ports with very similar input impedances to make the reflected signals identical. The high isolation network composed of two hybrids and two circulators plays a crucial part in achieving high transmitting to receiving (Tx-Rx) isolation. It is able to cancel out the inevitable reflected signals from the antenna ports and the leakage signals from the circulators.
Intelligent Signal Coverage Employing Hybrid-Mode Excitation in 5G Spoof Surface Plasmon Polaritons Antennas
14 March 2024 Behnam Mazdouri and Rashid Mirzavand consider different radiation features and signal levels in the spoof Spoof Surface Plasmon Polariton (SPP) antenna employing either separated or combined k−1 space harmonic or odd-mode. They propose a phase shift stub (PSS) for providing required phase delay. Then, the PSS is connected to a sinusoidally impedance-modulated spoof SPP antenna for hybrid-mode excitation. The antenna supports radiation features of the mentioned modes in separate and hybrid-modes, depending on phase delay value of PSS at the operating frequencies of 26 GHz-30 GHz.
Design of Wideband Reflectarray and Transmitarray Antennas With Low Sidelobe and Cross-Polarization Levels Using a Multifunctional Ultrathin Metasurface
12 March 2024 Yufang Wang, Yuehe Ge, Zhizhang Chen and Ziheng Zhou introduce an innovative approach for designing wideband, high-gain, low-sidelobe, and low-cross-polarization reflectarray (RA) and transmitarray (TA) antennas. The methodology leverages a groundbreaking metasurface endowed with the capability for independent amplitude and phase manipulation in both transmission and reflection modes. Initial characterization robustly verifies the metasurface’s proficiency in independently controlling amplitude and phase in reflection and transmission modes.
A WLAN Dual-Polarized Beam-Reconfigurable Antenna
08 March 2024 Saiju Li, Meie Chen, Zheng Li, Jianqiang Chen and Junhong Wang develop a novel wireless local area network (WLAN) antenna with dual-polarized and beam-reconfigurable ability for WLAN 2.4 GHz band application. The antenna is composed of a horizontally polarized (HP) antenna and a vertically polarized (VP) antenna. The radiation pattern of the HP antenna can be switched between an omnidirectional beam and four directional beams in the azimuth plane, while the VP antenna can generate an omnidirectional beam and eight directional beams. Then the antenna prototype is fabricated and measured.
Analysis of Scattering Characteristics Based on Crank-Nicolson Direct-Splitting Algorithm for Remote Sensing Problems
08 March 2024 Shida Gao, Hua Jiang, Yong Fan, Yongjun Xie, Haolin Jiang and Peiyu Wu propose an alternative Crank-Nicolson Direct-Splitting algorithm in open regions. To infinite extension of the computational domain, convolutional perfectly match layer with higher order formulation is proposed not only to further enhance the absorption at low-frequency band but also to decrease the reflections during the entire time domain simulation. Efficient method is proposed for scattering characteristics evaluation which ranges from near-field to far-field. Radar remote sensing Problems including ground penetrating radar and early warning radar are introduced to demonstrate the effectiveness of the algorithm.
Using Open Source to Accelerate Development of a Finite Element-Boundary Integral Code
07 March 2024 Niklas Wingren and Daniel Sjöberg describe how a finite element-boundary integral code using the adaptive cross approximation was developed by combining different existing open-source software packages with new code in Python. They provide a brief overview of the numerical methods used, but our focus is on the implementation and insights that might be useful to others who could benefit from using open-source software in their work. Three numerical examples are also presented to demonstrate accuracy, performance and use of complex materials. Our code is provided at github.com/nwingren/fe2ms both to demonstrate how the open-source packages were combined in practice, but also for those who wish to test the code themselves.
Low-Cost Indoor Localization Using Dual-Chip RFID Tag
05 March 2024 Jawad Ali, Kamol Kaemarungsi, Thipamas Phakaew, Muhammad Uzair, Adam Narbudowicz and Suramate Chalermwisutkul propose a low-cost dual-chip RFID tag antenna for indoor localization. The antenna integrates two RFID chips, each generating opposing radiation patterns. Angle-of-arrival based localization is performed with a single reader by analyzing the Received Signal Strength Indicator (RSSI) and the RSSI ratio of both chips. The antenna incorporates a mechanically adjustable reflector at the back that allows simple beam elevation control to tune the antenna for different indoor environments. The proposed dual-chip tag was measured in an indoor environment with different beam configurations.
Quasi-Deterministic Channel Propagation Model for Human Sensing: Gesture Recognition Use Case
29 February 2024 Jack Chuang, Raied Caromi, Jelena Senic, Samuel Berweger, Neeraj Varshney, Jian Wang, Chiehping Lai, Anuraag Bodi, William Sloane, Camillo Gentile and Nada Golmie describe a quasi-deterministic channel propagation model for human gesture recognition reduced from real-time measurements with our context-aware channel sounder, considering four human subjects and 20 distinct body motions, for a total of 120000 channel acquisitions. The sounder features a radio-frequency (RF) system with 28 GHz phased-array antennas to extract discrete multipaths backscattered from the body in path gain, delay, azimuth angle-of-arrival, and elevation angle-of-arrival domains, and features camera / Lidar systems to extract discrete keypoints that correspond to salient parts of the body in the same domains as the multipaths.
28-GHz Rural Close-to-Ground Propagation Field Test Results and Models
28 February 2024 Sumin David Joseph, Bill Gavin and Edward A. Ball conduct a set of 28 GHz close-to-ground propagation measurements for different rural outdoor scenarios at the National Spectrum Centre, Aberystwyth. A bespoke correlation based channel sounder and horn antennas are employed in the measurement system. The measurements provide large-scale path loss, time domain impulses and channel measurements that will be beneficial for rural future millimeter wave communication systems. Different scenarios, such as straight and elevated paths, zig-zag curved road and curved road in woods are explored and log-normal models are extracted.
Design and Optimization of an Ultra-Wideband Millimeter-Wave Circularly Polarized Metalens Antenna With Deep Learning Method
21 February 2024 Wen-Qiang Deng, H. Zhu, Yu-Xuan Xie, Zhengji Xu and Shu-Yan Zhu propose a novel approach that optimizes reference phases and transmission magnitudes at multiple frequencies assisting with deep learning method to design an ultra-wideband mm-wave circularly polarization antenna. The first neural network intelligently provides the required geometric parameters of the unit cells, while the second neural network validates the phase shifts and predicts the transmission magnitudes based on inputs from the first neural network. The particle swarm optimization (PSO) algorithm is also utilized to optimizes the reference phases at multiple frequencies to minimize the matching errors. To validate the design, a 3-D printed compact CP antenna is fabricated and measured.
Wideband Single and Dual Linearly Polarized Magneto-Electric Dipole Array Antennas for 5G/6G Millimeter-Wave Applications
19 February 2024 Lei Xiang, Fan Wu, Kai Chen, Renrong Zhao, Sai Ma, Yuanwei Zhu, Chao Yu, Zhi Hao Jiang, Yu Yao and Wei Hong propose a new taper-shaped linearly polarized (LP) magneto-electric (ME) dipole, excited by the U-shaped microstrip line through a coupling slot. An ultra-wide simulated impedance bandwidth of 85% (20.5-50.6 GHz) and 1.5-dB gain bandwidth of 73% (22.3-47.9 GHz) with a peak gain up to 7.7 dBi are achieved, combining the advantages of simple and compact structure, high integration, easy assembling and stable radiation characteristics. For proof-of-concept demonstration, a 4x4 LP array antenna is then implemented with an ultra-wide measured impedance bandwidth of 91.8% (18.8-50.7 GHz) and 3-dB gain bandwidth of 69.3% (19.8 to 40.8 GHz) as well as a peak gain of 18.0 dBi.
A Center-Fed Beam-Steerable Series Antenna Array With a Wide Matching Bandwidth
16 February 2024Sungeun Kim, Haegwon Park and Byung-Wook Min present a center-fed beam-steerable series antenna array that has both a wide matching bandwidth and easy control. The proposed matched feeding network for the series array is composed of impedance transformers and voltage-controlled phase shifters, and has a fractional bandwidth of 74%. The phase shifters are designed in a reflection-type configuration to minimize loss and reduce size. The 3-way power divider used in the proposed center-fed series array enable beam steering with only two control voltages for phase shifters.
A Way to Address Inherent Weakness in Conceiving the Ground Plane Geometry for a Microstrip Antenna
16 February 2024 Chandreyee Sarkar, Sk Rafidul, Chandrakanta Kumar and Debatosh Guha present an insight into the nature of ground plane (GP) current of a microstrip patch which is truly adverse in terms of generating cross-polar (XP) fields and minimally contributing to the primary radiation. This study also uses a theoretical basis in exploring a simple solution to mitigate the high XP values, specifically over the diagonal planes (D-planes). This actually turns out to be an engineered GP by clipping off its four corners. This has been thoroughly studied for a set of representative patch geometries and experimentally verified. A consistent XP reduction by 12–13 dB over D-planes has been ensured without affecting the impedance matching or antenna gains.
Reflectarray Antenna for Simultaneous Near-Field Fronthaul and Far-Field Backhaul Links in Next 5G FR2 Femtocells
14 February 2024 Álvaro F. Vaquero, Borja Imaz-Lueje, Marcos R. Pino and Manuel Arrebola present a reflectarray-based base station antenna to integrate both backhaul (BH) and fronthaul (FH). The reflectarray operates at 28 GHz in dual linear polarization, using one polarization for the BH and another for the FH. The BH is a pencil beam of maximum gain pointing in a certain direction, while the FH defines the coverage for a femtocell. The FH is used to generate the coverage within the near field radiated by the base station. The synthesis of the FH is carried out by means of a near-field phase-only synthesis (NF-POS), while the BH is analytic.
Optimization and Evaluation of a 3-D Ray Tracing Channel Predictor Individually for Each Propagation Effect
14 February 2024 Michael Schweins, Lennart Thielecke, Nils Grupe and Thomas Kürner present a 3D ray tracing channel predictor, which takes into account the relevant propagation phenomena like free space propagation, reflection, scattering, diffraction and transmission. The predictor is validated by two types of measurements and the relevance of the various propagation phenomena is analyzed based on predictions in a city using real base station locations and building data.
A Novel Yagi Element Integrated Nested Loop Quasi-Self-Complementary Dual-Port Combiner Radiator
13 February 2024 R. Gopika, Chinmoy Saha and Yahia M. M. Antar present a quasi-self-complementary radiator structure designed to operate simultaneously as a combiner and an antenna. The dual-port architecture comprises axially symmetric nested microstrip loops. The upper half of the radiator structure placed on the top plane is nearly complementary to the lower half on the bottom plane. The nested loop is loaded with a Yagi element for improved performance. This additional element in the radiator enhances the end-fire radiation from the nested loop wideband dual port structure without disturbing the parallel combiner action.
2-D Ray-Tracing Model for Multilayer Dielectric Dome Arrays With Inner Reflections
12 February 2024 Maria Pubill-Font, Francisco Mesa, Astrid Algaba-Brazález, Sarah Clendinning, Martin Johansson and Oscar Quevedo-Teruel present a streamlined implementation of ray tracing for fast and efficient numerical analysis of the far-field radiation performance of 2D multilayer dielectric lenses combined with phased arrays. Unlike commercial physical-optical methods, the proposed ray-tracing method is capable of computing the effects of internal reflections in the dome in a multilayer configuration. In addition, the method estimates the absorption losses as a result of the Joule effect.
Kriging Methodology for Uncertainty Quantification in Computational Electromagnetics
08 February 2024 Stephen Kasdorf, Jake J. Harmon and Branislav M. Notaroš present the implementation and use of the Kriging methodology, i.e., surrogate models based on Kriging interpolation, in uncertainty quantification (UQ) in computational electromagnetics (CEM). They provide consistent, unified, and comprehensive description, derivation, implementation, use, validation, and comparative study of accuracy and convergence of several advanced Kriging approaches, namely, the universal Kriging, Taylor Kriging, and gradient-enhanced Kriging methods, for reconstruction of probability-density function in UQ CEM problems.
Improving DOA Estimation via an Optimal Deep Residual Neural Network Classifier on Uniform Linear Arrays
05 February 2024 Haya Al Kassir, Nikolaos V. Kantartzis, Pavlos I. Lazaridis, Panagiotis Sarigiannidis, Sotirios K. Goudos, Christos G. Christodoulou and Zaharias D. Zaharis improve and evaluate the effectiveness of the neural network (NN) architecture in the domain of estimation of direction of arrival (DOA), with an emphasis on a multi-class classification task with grid resolutions of 0.25 and 0.1. Specifically, a comprehensive assessment is performed to determine the competence of a residual NN (ResNet) in predicting the angle of arrival (AOA) of intercepted signals. Such signals are received by a 16-element uniform linear array and are subjected to real-world noise conditions.
Beam Steering Performance of an X-Band Offset Parabolic Cylindrical Reflector Fed by Triple-Mode Horn Integrated With Risley Prism and Phase Correcting Dielectric Lens
05 February 2024 Kaushik Debbarma, Satish Kumar Sharma, Jia-Chi Samuel Chieh and Nhat Truong present a broadband 1-D high-gain beam steering solution to steer sum and difference patterns for tracking the optimum common scatter volume of troposcatter links at X -band. The novel steering arrangement consists of a D=70 cm offset parabolic cylindrical (OPC) reflector fed by a triple-mode circular waveguide (TM-CW) horn antenna integrated with a two-element dielectric wedge-based Risley prism and a parabolic phase correcting dielectric lens (PCDL). The proposed hybrid beam steering reflector-feed obviates the need for complex 3-axes based gimbals to mechanically steer the conventional reflector-feed assembly.
Going Beyond a Simple RIS: Trends and Techniques Paving the Path of Future RIS
31 January 2024 Kinza Shafique and Mohammad Alhassoun review recent developments in reconfigurable intelligent surfaces (RIS) technology with a special emphasis on tuning techniques, hardware concepts, RIS empowered by artificial intelligence techniques, and applications for next generation of networks. Finally, a viewpoint on the difficulties and potential directions of intelligent metasurfaces are also presented.
The Effective Number of Degrees of Freedom of the Far-Fields Radiated by Rectangular Current Sheets
30 January 2024 Ting Zang and Gaobiao Xiao evaluate numerically the number of degrees of freedom (NDF) of the electromagnetic far-fields generated by current sheets under certain noise level in the environment by directly sampling on the constellation of the propagation modes in free space. The electric fields in the far region are efficiently calculated by using the far-field approximation, and the effective numbers of degrees of freedom (ENDFs) are obtained through singular value decomposition (SVD) incorporating noises. The results show that ENDF is proportional to the area of the current sheets.
A Low-Profile Broadband Filtering Dielectric Resonator Antenna Based on SISL With the Improvement of Suppression Level
26 January 2024 Ningning Yan, Cong Wang, Yu Luo and Kaixue Ma present a substrate integrated suspended line (SISL) based broadband filtering dielectric resonator antenna (DRA) with the improvement of suppression level to achieve a low-profile, wide-bandwidth, and highly selective design. The dielectric resonator is cylindrical and fed from the bottom by a microstrip-coupled slot. The dual head structure with the designed open stub can provide two radiation nulls on both sides of the passband for the filtering function and can excite three resonant modes (HEM 11δ, HEM 11δ, and TE131 mode) at different resonant frequencies to enlarge the impedance bandwidth of the proposed antenna.
Connected Antenna Arrays With Beamsteering Capability for On-Package Millimetre-Wave Applications
25 January 2024 Md Rasheduzzaman Al-Amin, Reza Shamsaee Malfajani, Elham Baladi and Mohammad S. Sharawi design, fabricate and measure on-package, beamsteerable, slot-based connected antenna arrays (CAA), namely a single slot connected antenna array (SSCAA) and a double slot connected antenna array (DSCAA) for millimeter-wave (mm-wave) applications. Both structures are designed in a multi-layer stack-up fashion considering the package environment. The proposed SSCAA and DSCAA show 12.3% (centered at 27.55 GHz) and 16.5% (centered at 30.2 GHz) of measured bandwidths (−10 dB return loss) in their respective operating frequency bands. The measured realized gains of the SSCAA and DSCAA are 9.89 dBi and 12.5 dBi at broadside, demonstrating efficiencies of 89% and 78% respectively.
Mm-Wave Building Penetration Losses: A Measurement-Based Critical Analysis
18 January 2024 Silvi Kodra, Marina Barbiroli, Enrico Maria Vitucci, Franco Fuschini and Vittorio Degli-Esposti carry out a measurement campaign at 27 and 38 GHz to investigate the coverage and interference assessment issues of mm-wave radio links in in-building applications, and in particular, analyse the outdoor-to-indoor and through-floor attenuation. It is observed that in-building losses heavily depend on the building type, and that modern construction techniques make through-floor penetration almost impossible.
Ultra-Wideband Antennas for Wireless Capsule Endoscope System: A Review
17 January 2024 Ben Li, Yifan Wang, Junchi Zhao and Jingjing Shi present a comprehensive review of different ultra-wideband UWB antenna designs for wireless capsule endoscopy (WCE) system. In-body and on-body UWB antennas are classified according to the radiative performances and structure. Particular attention is also paid to the models used in simulation and experiment, as well as some key performance parameters and technologies in the process of antenna design. This extensive summary of UWB antennas for WCE systems will help to understand the prospects and challenges in this field.
Compact Dielectric Resonator Antenna With Improved Bandwidth via Loading of Metal Ring
16 January 2024 Hui Gu and Lei Ge propose a novel dielectric resonator antenna (DRA) characterized by a compact size and wide bandwidth. The achievement of wideband performance involves the introduction of a metallic ring structure inside the dielectric resonator, ensuring that the antenna’s volume remains compact. Fundamental and higher-order modes, TM01δ, TM021+δ of the cylinder DRA are first investigated by using E-field distribution analysis, and it is found that these two modes are hard to resonate in proximity to each other. Therefore, a thin metal ring, acting as a perturbation structure is inserted into the DR to perturb the E-field of the higher-order mode and reduce its resonant frequency.
A Dual-Beam Filtering Antenna Based on Dual-Mode Patch Loaded With π-Shaped Vias
15 January 2024 Lingyan Zhang, Tiannan Ni, Jin Shi, Gu Liu and Kai Xu utilize a dual-beam filtering patch antenna is proposed, wherein a symmetrical π-shaped metal vias-loaded dual-mode patch and a cross-shaped metal strip. The dual-mode patch resonator is realized through the loading of metal vias in the weak field region of mode TM21, which effectively moves mode TM01 closer to TM21. Using a cross-shaped metal strip to excite the dual-mode patch resonator not only provides a reflection zero and broadens the bandwidth, but also generates two radiation nulls through zero coupling, thus improving the frequency selectivity.
Aperture Efficiency of Non-Uniform Antenna Arrays With Controlled Sidelobe Level
15 January 2024 Ahmed Alieldin and Yi Huang presents a comprehensive study and proposes accurate mathematical modelling of the aperture efficiency of an antenna array which is divided into two components: power-loss efficiency (which dominates total aperture efficiency) and power-distribution efficiency to gain a better understanding. The paper also shows how the sidelobe level of an antenna array is linked to these efficiencies and how they can be improved. It is proved that the aperture efficiency exponentially decays when lowering the sidelobe level. However, it converges to a certain value when the sidelobes vanish.
Calderón Strategies for the Convolution Quadrature Time-Domain Electric Field Integral Equation
15 January 2024 Pierrick Cordel, Alexandre Dély, Adrien Merlini and Francesco P. Andriulli introduce new integral formulations based on the convolution quadrature method for the time-domain modeling of perfectly electrically conducting scatterers that overcome some of the most critical issues of the standard schemes based on the electric field integral equation (EFIE). The standard time-domain EFIE-based approaches typically yield matrices that become increasingly ill-conditioned as the time-step or the mesh discretization density increase and suffer from the well-known DC instability. This work presents solutions to these issues that are based both on new Calderón strategies and quasi-Helmholtz projectors regularizations.
An Integrated DRA-Based Large Frequency Ratio Antenna System Consisting of a MM-Wave Array and a MIMO Antenna for 5G Applications
03 January 2024 Awab Muhammad, Muhammad U. Khan, Reza Shamsaee Malfajani, Mohammad S. Sharawi and Moath Alathbah present a large frequency ratio antenna that covers the widely separated 5G bands. The proposed antenna consists of a 2-element rectangular DRA (rDRA)-based MIMO antenna for the sub-6 GHz band, with an embedded 1×4 cylindrical DRA (cDRA) array covering the mmW band. The rDRAs are fabricated through a cost and time-efficient 3D printing process, whereas small dimensions of cDRAs are precisely machined through a CNC. The proposed antenna has a measured impedance bandwidth of 31.63% at 4.9 GHz and 21.5% at 28 GHz. The antenna has a peak gain of 6.6 dBi at the sub-6 GHz and 12 dBi at the mmW bands.
4×4 UWB Phased Array Antenna With >51° Far-Field Scanning Range for Wireless Power Transfer Application
02 January 2024 Adnan Basir Patwary and Ifana Mahbub design a single unit antenna to achieve ultrawideband (UWB) operation while maintaining high gain and unidirectional radiation pattern. It determines the array element spacing based on the theoretical modeling and simulation and measurement based validation to achieve the highest gain, minimum coupling coefficient, and lower side lobe level (SLL). In order to achieve beam steering, each 2×2 subarray is considered as a single quadrant thus dividing the 4×4 phased array antenna into four quadrants where all 16 single elements are individually fed. The far-field radiation beam is steered by controlling the phase difference between each quadrant.
Analytical Equations for Designing Meander Line Antennas
01 January 2024 Ngu War Hlaing, Kamilia Kamardin, Yoshihide Yamada, Takuji Arima, Masaharu Takahashi and Naobumi Michishita note that the prior self-resonant equations in Meander Line Antenna (MLA) design included only inductive reactance (XC), neglecting the capacitive reactance (XD) equation. They address the gap by introducing new design equations, presenting a newly derived XD equation and an improved Q factor expression. The inadequacies of the existing Q factor equation, reliant on the radius of a sphere encompassing the antenna, are addressed by proposing a more fitting expression that incorporates antenna structural parameters using the ratio of reactance to resistance. The overview of existing design equations sets the stage for the introduction of these newly developed equations.
Wideband/Dual-Band Dielectric Filtering Inverted-L Antenna With Reflective and Quasi-Reflectionless Radiation Nulls
29 December 2023 Wen Zheng, Shiyan Wang, Yin Li, Zai-Cheng Guo, Gang Zhang, Li Yang, and Roberto Gómez-García propose a class of dielectric filtering inverted-L antenna with reflective- and quasi-reflectionless-type radiation nulls to achieve wideband or dual-band operation. To this aim, a dual-function dissipative branch is exploited, which is in-parallel loaded at the feedline of the microstrip-fed dielectric inverted-L antenna. This absorptive branch, which is terminated in a grounded resistor, exhibits a quasi-complementary frequency response with regard to the one of the antenna. In this manner, it can mostly absorb the out-of-band RF-signal power not radiated by the antenna, hence creating quasi-reflectionless-type radiation nulls.
True-Time-Delay Metasurface Assisted Broadband and Planarized Resonant Cavity Antenna
29 December 2023 Tayyab A. Khan and Alex M. H. Wong planarize a recently proposed resonant cavity antennas (RCA), which achieved a broad 3dB bandwidth of over 20% using a spherically modified ground (SMG), by replacing the SMG with a true-time-delay metasurface (TTD-MS) that mimics the both reflection phase shift and time-delay of the SMG over antenna’s entire operation bandwidth. They verify the proposed method through full-wave simulations and experimental measurements that demonstrate an impedance bandwidth (S11≤−10dB) of 32% and a 3dB-gain bandwidth of 21.3% (from 11.95 GHz to 14.8 GHz), with a peak gain of 17.5 dBi.
Nyström-Type Technique for Electromagnetic Wave Scattering in Inhomogeneous Material, Plasma and Metamaterial Slabs
28 December 2023 John L. Tsalamengas present a simple, stable, and spectrally-accurate quasi-analytical method for studying the reflection, transmission, and radiation of EM waves in the presence of single-layer or multilayer material, plasma, or metamaterial slabs that are inhomogeneous along the normal to the slab interfaces. Our approach formulates the problem as a linear Volterra integral equation of the second kind, discretized using an entire-domain Nyström method with a high-order Gauss-type quadrature.
Physical Optics Applied to Parallel-Plate Lens Antennas
26 December 2023 Francisco Mesa, Mingzheng Chen, Pilar Castillo-Tapia and Oscar Quevedo-Teruel use the Physical Optics (PO) method to derive simplified expressions to compute the radiation electric fields of planar graded-index and geodesic lenses based on a parallel-plate waveguide (PPW) implementation. If the PO method is combined with ray-tracing (RT) techniques, the resulting RT-PO procedure is capable of computing radiation patterns and gain of the PPW-based lens antennas when their apertures have a general shape and the electric field is vertically polarized. The RT-PO method is validated by comparing it with the full-wave simulation results of the commercial software ANSYS HFSS for three application cases.
A Dual-Polarized and Wideband Switchable Absorption/Transmission Frequency Selective Surface With Multispectral Functionality
25 December 2023 Huangyan Li, Youyi Feng, Minxin Zhao, Xiang Wang, Danilo Brizi, Xiaoxing Fang, Jun Hu, Boyu Sima, Zhiyuan Zong, Wen Wu and Agostino Monorchio develop a microwave absorption/transmission switchable frequency selective surface (A/T-SFSS) with enhanced multispectral functionality in the visible and infrared spectra. By controlling the flowing liquid medium (pure water in this work), efficient manipulation of two opposite states, absorption and transmission, can be achieved in the microwave frequency band with a wide switchable bandwidth. When functioning as a wideband absorber, the proposed A/T-SFSS exhibits an absorption rate over 90% from 6.50 GHz to 10.48 GHz.
SIW Sub-Array Antenna With High Isolation Offering Dual-Polarized Monopulse Patterns
25 December 2023 Maksim Kuznetcov, Symon K. Podilchak and Mathini Sellathurai present a high isolation antenna which offers dual-polarization monopulse beam patterns, making the design suitable for polarization diverse or full-duplex (FD) systems. The single-layer structure is defined by a network of 2-D sub-arrays oriented in a cross-shape configuration using series-fed slots in substrate integrated waveguide (SIW) technology. Also, the proposed design exploits dual-differential feeding to achieve a −10 dB impedance matching bandwidth (BW) from 23.2 GHz to 25.4 GHz, and measured isolation values are more than 70 dB (peaking to about 90 dB) over this same operating range.
Low-SAR and High-FBR Patch Antenna With Small Ground Size for Wearable Devices
14 December 2023 Shu-Wei Yu, Xiao Zhang, Qiong-Sen Wu, Lei Zhu, Tao Yuan and Qing-Hua Jiang propose a high front-to-back ratio (FBR) microstrip patch antenna with small ground plane size in this article. In order to suppress the serious back lobe brought by such a small ground, a hybrid loading technique consisting of coupled branch (CB) and resistor-loaded ground slot (RLGS) is introduced. Through the hybrid loading, extra magnetic currents on the ground are excited, by which the backward radiation of the original patch could be cancelled.
Cusp Phased Metasurfaces for Wideband RCS Reduction Under Broad Angles of Incidence
15 December 2023 Mustafa K. Taher Al-Nuaimi, William G. Whittow, Guan-Long Huang and Rui-Sen Chen presents an efficient and effective design approach of the phase distribution calculation across metasurface for significant radar cross section (RCS) reduction of a circular polarization (CP) and liner polarization (LP) radar waves. The RCS reduction using the proposed design approach is achieved by imposing a novel cusp phase mask (which is usually used to generate 3D self-accelerating and self-healing cusp beams) at each geometric phased anisotropic unit cell composing the proposed cusp phased metasurface.
Seamless Integration Technology for Filtenna Toward 5G/6G Wireless Communications
13 December 2023 Wei Hong, Zi-Jun Guo and Zhang-Cheng Hao review the design methodologies, operational principles, and implementation strategies of filtennas with illustrated examples in this paper. Whether in the context of 5G or 6G networks, base transceiver stations (BTS) require a substantial number of radio frequency (RF) transceiver chains and antenna array, particularly in mmWave frequency bands. It is known that bandpass RF filters between antenna elements and transceivers are key components for suppressing out-of-band spurs and interference. The single board seamless integration of transceivers and antennas has become a growing trend. It means there is no extra room for a large number of filters at mmWave bands, leading to the emergence of integrated designs that combine filtering circuitry with antennas, known as filtenna or filtering antenna.
A Design of Dual-Polarized Composite Patch-Monopole Antenna With Reconfigurable Radiation Pattern
13 December 2023 Thanh Tung Phung, Son Xuat Ta, Khac Kiem Nguyen and Nghia Nguyen-Trong describe a design of dual-polarized composite patch-monopole antenna with reconfigurable radiation pattern. The design consists of a double differential-feed patch loaded with four vertical monopoles symmetrically. The monopoles are connected to or disconnected from the ground plane (GND) by changing the ON/OFF states of p-i-n diodes. By adjusting the connections between the monopoles and GND, the pattern reconfigurability (i.e., one widebeam and three narrow-beam modes) can be achieved for each polarization. The proposed antenna can switch the beam in two dimensions separately (xz− and yz− plane). The proposed antenna is characterized computationally and validated experimentally.
$An X-Band Linear-to-Circular Polarizer With High Refractive-Index Metamaterials$

An X-Band Linear-to-Circular Polarizer With High Refractive-Index Metamaterials
13 December 2023 Yat Sing To, Xue Ren, Quan-Wei Lin and Hang Wong present a novel wideband low-profile linear-to-circular polarizer based on high refractive-index metamaterials in the X band. The proposed design is a multilayer structure that is built from two kinds of metamaterial unit cells consisting of 4-H-shaped strips and 1-H-shaped strips. Combining the two unit cells realizes the flexible and independent control of the refractive index difference between two orthogonal E-field components and thus achieves a consistent 90-degree phase delay over a wide bandwidth.
Compact Omnidirectional Circularly Polarized Antenna via Alford Loop and Wire-Patch Structure Combination
08 December 2023 Francesco Positano, Luca Santamaria, Robert Staraj and Leonardo Lizzi present a compact single-fed omnidirectional circularly polarized (OCP) antenna. The circular polarization is obtained by combining an Alford Loop (AL) and a Wire-Patch (WP) radiating structures, which are used to generate two orthogonal E-field components. The antenna exhibits a clear right-handed circular polarization (RHCP) with a dipole-like omnidirectional radiation pattern. A prototype has been realized using two FR-4 printed circuit boards (PCBs) and experimentally tested.
The Path Reduction Factor for the Prediction of Rain Attenuation Affecting Short EHF Terrestrial Links
08 December 2023 Francesco Capelletti, Carlo Riva, Giuseppe Roveda and Lorenzo Luini Investigate the path reduction factor (PRF), a key element of semi-empirical rain attenuation statistics prediction models, to shed some light on its value for links shorter than 1 km. PRF is here calculated from simulations underpinned by the use of the Enhanced Synthetic Storm Technique (E-SST) to take into account the rain rate spatial distribution along the path. This novel approach, in contrast with the more customary one of inferring a PRF model from measurements, offers the advantage of avoiding considering any unwanted additional attenuation not due to precipitation, but typically linked to system-induced effects.
High-Permittivity Dielectric Half-Loop Yagi-Uda Antenna With End-Fire Radiation
07 December 2023 Wen Zheng, Shiyan Wang, Mengjiao Tang, Gang Zhang, Wang Ren and Changzhou Hua propose a kind of half-loop Yagi-Uda antenna made of high-permittivity dielectric to realize end-fire radiation. As two typical materials with high permittivity, low-loss zirconia ceramic and liquid pure water are here employed for the proposed antenna to attain high radiation efficiency and support the characteristic of pattern reconfigurability, respectively. The thin dielectric waveguide with high permittivity is here used as the metal wire of conventional wire antennas, due to its traveling-wave radiation under TM01 mode. The different radiation characteristics of the electrically small loop and full-wave loop antennas are discussed.
Characteristic Modes Analysis for Circularly Polarized 1-Bit Dual-Layer Transmitarray Design
07 December 2023 Francesco Alessio Dicandia and Simone Genovesi present a novel approach for designing a circularly polarized (CP) transmitarray (TA) by resorting to the characteristic modes analysis (CMA) . Two miniaturized dual-layer polarization-insensitive unit cells are tailored to provide the two copolar transmission coefficient phase states that act as a 1-bit spatial phase shifter in the TA. The exploitation of a pair of characteristic modes (CMs), radiating either right-handed CP (RHCP) or left-handed CP (LHCP) scattered field, is at the basis of the TA operation.
Sparse Array Mutual Coupling Reduction
05 December 2023 C. Larmour, N. Buchanan, V. Fusco and M. Ali Babar Abbasi provide a concise overview of recent developments in sparse antenna arrays, with a specific focus on techniques for reducing mutual coupling in this article. It explores the concept and definitions of sparse arrays in different applications, highlighting their historical significance in antenna theory. The paper addresses the mutual coupling problem and presents reduced coupling geometrical configurations through illustrative examples. Various mutual coupling compensation techniques are discussed. The paper conducts a comprehensive comparison of multiple array design optimisation techniques, including genetic algorithm, covariance matrix adaptation evolution strategy, particle swarm optimisation, trust-region framework, Nelder-Mead simplex algorithm, interpolated Quasi-Newton, and classic Powell.
Linearly Scanning Spoof Surface Plasmon Polaritons Leaky-Wave Antenna With High Scanning Rate
3 December 2023 Yue Wang, Shengying Liu, Chunsheng Guan, Hao Yu, Jinxiang Wang, Qun Wu, Changfei Zhou and Xumin Ding propose a wide-angle linearly scanning leaky-wave antenna (LWA) based on spoof surface plasmon polaritons (SSPPs) with a very high scanning rate. A sine curve period is introduced to construct the SSPPs transmission line in the form of a sine curve, which can transform the dispersion curve to the fast wave region to realize the desired dispersion properties for linearly high scanning rate LWA. The simulated results show that the proposed LWA achieves a scanning angle range of 109° over a narrow operation bandwidth of 7.73–8.13 GHz, implying high linearity, and a high scanning rate.
Dual-Linearly Polarized Magneto-Electric Dipole Antenna for In-Band Full-Duplex Applications
01 December 2023 Qian Tan and Kwai-Man Luk propose a dual-linearly polarized (DLP) magneto-electric (ME) dipole antenna for the in-band full-duplex (IBFD) application. It is formed by ME dipoles with a shared central part, giving a compact and symmetrical antenna structure. It has four isolated channels, two for dual-LP transmitting (TX) and the other two for dual-LP receiving (RX). Due to the symmetrical structure, it can provide similar radiation patterns for both the TX and RX ports. Good isolation between any two of all four ports is obtained over a wide frequency range by modifying the antenna structure without introducing any additional complex feeding structures.
A Step-by-Step Design Methodology for Broadband Tunable Microwave Metasurface Absorbers Using Theory of Characteristic Modes
29 November 2023 Zihao Ning, Mengmeng Li, Dazhi Ding, Xia Ai, Jiaqi Liu and Chao-Fu Wang develop a characteristic mode (CM)-based design methodology for the reconfigurable microwave metasurface absorbers (MMA) with using commercially available substrates. Theoretical intrinsic connection between modal behaviors and absorption properties is first formulated for the design of the structures. As a proof of the method, a broadband MMA consisting of butterfly elements is step-by-step designed. The positions and values of the impedance loading are determined based on the modal significances and modal currents for broadband operation. The absorption performance is evaluated by the formulated theoretical model and verified by full-wave simulation.
User Effects on Mobile Phone Antennas: Review and Potential Future Solutions
29 November 2023 Igor Syrytsin, Gert Frølund Pedersen and Shuai Zhang explore the significant impact of human proximity on antenna design evolution in mobile communication from GSM to LTE and future 5G technologies. The paper offers a comprehensive view of the challenges posed by human interactions in current antenna designs, alongside modern solutions to mitigate these issues.
Design of a Dual-Branch Resonator End-Launcher for Low-Loss WBAN Communications Using Wearable Waveguide Surfaces
28 November 2023 Maria El Bacha, Fabien Ferrero and Leonardo Lizzi propose a compact 30 mm x 30 mm dual-branch resonator end-launcher to enable communication through a waveguide surface manufactured with textile-compatible material at 2.4GHz. A 25 mm x 25 mm clearance zone area is respected for electronic component integration. The end-launcher topology uses a balanced dual-branch configuration to maximize electromagnetic coupling with the flexible waveguide surface. A design methodology is proposed to co-design the end-launcher and the waveguide surface.
Compact Multi-Beamforming Networks Based on Generalized Joined Coupler Matrix With Flexible Beam Angles and Low Sidelobe Levels
27 November 2023 Yang Xu, He Zhu and Y. Jay Guo propose a design of generalized joined coupler (GJC) matrix as a multibeam feeding network using planar circuits and is verified experimentally. The GJC matrix design is built based on a mixture of one-section and two-section branch-line couplers, which are able to realize a wide range of coupling coefficients. A thorough investigation from theoretical analysis to electromagnetic modeling is conducted on one-section and two-section branch-line couplers, and a general design guideline is given for choosing the appropriate type and dimensions for each coupler in a GJC matrix. Then, two types of BFN using microstrip line working at 5 GHz and stripline working at 12 GHz are designed, fabricated and measured, respectively.
Wideband and Wide Beam Scanning Dual-Polarized Phased Array Antenna-in-Package Design for 5G Applications
27 November 2023 Haoran Zhang and Atif Shamim utilize multiple design strategies, such as employing stacked patch topology, electromagnetic band gap (EBG) structures, and the rotation of elements to obtain a true wideband performance. The single element of the phased array was a dual linear polarized stacked patch antenna with notched corners. Compared to a standard patch antenna, the bandwidth was enhanced by 15.3%. The undesired mutual coupling between elements was minimized by rotating nearby elements and introducing EBG structures between the adjacent elements.
Compact Amplitude-Monopulse Antenna for Joint Two-Dimensional Direction Finding and Sectorized Communications in the 2.4 GHz ISM Band
23 November 2023 Miguel Poveda-García, José Antonio López-Pastor, María Campo-Valera, Alejandro Gil-Martínez, David Cañete-Rebenaque and José Luis Gómez-Tornero propose a compact antenna design to synthesize two-dimensional amplitude monopulse radiation patterns, with application to integrated sensing and communications in the ISM 2.4 GHz band. The antenna makes use of two air-filled leaky waveguides to generate four diagonally scanned beams without the need of complex feeding networks. The design demonstrates the generation of monopulse patterns in the two perpendicular planes of the antenna, covering an angular field of view of 40° X 60° where the Direction of Arrival can be estimated. The simple structure and compactness of this antenna makes it very suitable for low-cost multi-functional joint radar-communications using commercial wireless networks.
Bandwidth Enhancement of H-Plane MIMO Patch Antennas in Integrated Sensing and Communication Applications
20 November 2023 Lina Ma, Zijian Shao, Jun Lai, Changzhan Gu and Junfa Mao propose a low-cost compact decoupled bandwidth enhancement technique to address the high mutual coupling issue between wideband closely-spaced multiple-input and multiple-out (MIMO) patch antennas. The wideband decoupling property is realized by combining two decoupling circuits introduced by defected ground structure (DGS) and coplanar decoupling structure, respectively. An equivalent circuit is given to clarify the decoupling mechanism and provide physical insight. To validate the feasibility of the proposed design scheme, two prototypes of decoupled wideband patch arrays based on coplanar-fed and probe-fed schemes are simulated, fabricated, and measured in the 5.8 GHz ISM band, respectively.
A Compact, Circularly-Polarized, Substrate-Integrated Waveguide, Millimeter-Wave Beamsteering System for 5G Mobile Terminals
17 November 2023 Khaled Al-Amoodi, Rashid Mirzavand, Mohammad Mahdi Honari, Jordan Melzer, Duncan G. Elliott and Pedram Mousavi propose a compact, circularly-polarized (CP), end-fire, 4×1 continuous beamsteering antenna array implemented using substrate-integrated waveguides for 5G mobile terminals. The purpose of this system is to complement the radiation patterns of planar phased arrays on the faces of a typical mobile terminal. The proposed system seamlessly integrates previously-presented antennas and polarizers, with adjustable phase shifters and a feeding network in a multi-layered, single stack, printed circuit board (PCB) for continuous beamsteering in a compact package.
Dual-Band Shared-Aperture Base-Station Antenna Array With Dual Polarization Using Filtering Magnetoelectric Dipole Antenna
17 November 2023 Zhi Jing Xiao, Yun Fei Cao, Jia Sheng Lin, Yu Lan and Quan Xue present a dual-band shared-aperture antenna array using a filtering magnetoelectric (ME) dipole antenna for the application of mobile-communication base station. It is realized by interleaving a lower-band (LB) filtering ME dipole antenna operating from 1.7 to 2.8 GHz and four higher-band (HB) patch antennas in the band of 3.3-3.9 GHz. The filtering performance of the proposed ME dipole antenna is realized by U-shaped slots etched on the radiating arms and a cross-shaped microstrip line inside the aperture of the magnetic dipole, and used to realize a high cross-band isolation.
Modeling and Characterization of Electrically Small Ultrawideband Antenna for Headstage-Based Wireless Neural Signal Recording System
16 November 2023 Adnan Basir Patwary, Nishanth Virushabadoss, Rashaunda Henderson and Ifana Mahbub use microsystems that record neural signals collected simultaneously after neural simulation in the diagnosis of neural diseases. They propose a 15× 15 mm2 slot antenna with a 50 Ω microstrip excitation line. The slot antenna is created by the addition of slots in the ground plane which is a common miniaturization method as it results in ultrawideband operating frequency. A lumped component-based model along with a 3D EM model of the modified SMA connector used for the measurement and headstage model is also developed to observe the effect on the antenna performance.
A Slot-Connected Cavity Design With Corresponding Equivalent Circuit Model Analysis for Fully Metallic 3-D Vivaldi Antenna for Wireless Power Telemetry Applications
16 November 2023 Sunanda Roy, Karthik Kakaraparty and Ifana Mahbub present the design of fully metallic 3D Vivaldi antenna that can be used for wireless power transmission applications. The 3D antenna consists of 1) a tapered profile, 2) a rectangular cavity, and 3) a horizontal slot cut that is used as a transition between the cavity and the tapered profile. The proposed antenna design is fabricated using two distinct approaches, the first of which is a 3D metal additive manufacturing (AM scheme) with a sequential material layer addition technique. The second version is based on the CNC milling (CNCM) technique implemented by selectively removing material in a controlled way.
On Performance Characterization of Harmonic Transponders
15 November 2023 Milan Polivka and Jeff Frolik show that harmonic transponders’ conversion loss is dependent jointly on interrogation power, interrogation frequency, and interrogation angle. This coupled nature of the device’s behavior necessitates performance metrics that capture these characteristics. They present a methodology to generically test these devices and propose metrics that capture the noted dependencies.
Dual-Polarized Magneto-Electric Dipole for 5G 28-GHz Phased Array Applications
15 November 2023 Giuseppe Scalise, Emilio Arnieri, Giandomenico Amendola, Mohadig W. Rousstia, Sergio Pires and Luigi Boccia report a low-profile dual-polarized magneto electric (ME) dipole antenna configuration implemented on standard multilayer PCB technology. The proposed radiator is conceived for dual-polarized 28 GHz 5G phased array applications. Wideband operation is achieved by applying several low-frequency techniques which allow to fulfil the 5G requirements without increasing the dielectric core thickness. A 4×8 ME-dipole phased array is then designed, fabricated, and tested. The measured beam scanning range without the blindness in the E-plane is ±55° for the vertical polarization. Stable radiation patterns and a gain of up to 22 dBi are also achieved.
A Lightweight Spherical Generalized Luneburg Lens Antenna With Low Cross-Polarization Over a Wide Range in Azimuth and Elevation
14 November 2023 Maral Ansari, Oskar Zetterstrom, Nelson J. G. Fonseca, Oscar Quevedo-Teruel and Y. Jay Guo present a novel dual-slant polarized three-dimensional (3D) periodic Luneburg lens with a diameter of 390 mm (4.6λ0 at 3.55 GHz). Copper-plated cubes with truncated corners are placed in a body-centered cubic (BCC) lattice and held together with layers of Rohacell foam. The sizes of the cubes are varied to realize the gradient refractive index (GRIN) profile of a generalized Luneburg lens at a low cost, with a low weight and loss.
Enhancing Gain Through Optimal Antenna Element Distribution in a Thinned Array Configuration
08 November 2023 Michael Ortiz, Md Nazim Uddin, Marisol Roman Guerra and Elias A. Alwan present an array thinning approach for a 25-element antenna array arranged in a 5×5 grid at 5.4 GHz. Our goal is to eliminate a maximum number of antenna elements with minor gain loss and hence reduce the array size, weight, cost, and power requirements. Consequently, the space saved by the thinned array configuration presents opportunities to integrate additional antennas and hardware, allowing for a low-profile antenna-in-package. Our study showed that a 64% array reduction (from 25 to 9 probe-fed patch antennas) achieved an array gain comparable to a full array configuration.
Dispersion Characteristics and Applications of Higher Order Isosceles Triangular Meshes in the Finite Element Method
08 November 2023 Yuhua Niu, Jinbo Liu, Wen Luo, Zengrui Li and Jiming Song proposed research shows that under the same order, the equilateral triangular meshes have the most uniform dispersion distribution. The isosceles triangles with equal base and height have more uniform dispersion error than the square meshes, while the maximum phase error is similar. Taking the rectangular waveguide as an example, the relative errors in the cut-off frequency are analyzed based on different meshes.
Accurate Determination of Antenna Gain in the 300-GHz Band Using Amplitude Center Estimated From Electrooptic Near-Field Measurements
07 November 2023 Yuta Hayashi, Yu Katsuue, Yusuke Tanaka and Shintaro Hisatake propose and demonstrate an accurate antenna-gain determination method using the distance between the amplitude centers (ACs) of the antennas determined from the spatial phase distribution of the near field measured based on an electrooptic technique. Employing a WR-3.4 horn antenna, we show that at 286 GHz, the proposed method determines antenna gain with the same level of error even when the antenna separation distance is 1/5 shorter than that obtained using the conventional method that employs the physical distance between the antenna apertures in the Friis equation.
Application of Coherently Radiating Periodic Structures for Feeding Subarrays in Limited-Scan Arrays
07 November 2023 Elizvan Juarez, Marco A. Panduro, David H. Covarrubias, Alberto Reyna and Carlos Del Rio present a new design technique to improve the reduction of phase shifters using sub-arrays and CORPS (coherently radiating periodic structures) technology. The CORPS network generates the values of cophasal excitation with reduced input ports. These values feed an optimal sub-arrays structure. Furthermore, fixed and variable amplifiers allow a low SLL (side lobe level) by using a raised cosine amplitude distribution along sub-arrays inputs. The theoretical model of CORPS-Subarrays, numerical and experimental results of several design cases are presented. The proposed design achieves a ±14° scanning range with a higher reduction of phase shifters than other techniques presented previously in the state of art.
Efficient Calibration of Colocated MIMO Radar
06 November 2023 Ricard L. Grove and Jørgen Dall present a calibration technique that reduces the number of measurements required to obtain adequate calibration coefficients, compensating for all system imperfections that can be described in matrix form. This includes channel imbalance and mutual coupling under the assumption of minimum scattering antennas. The proposed technique estimates the calibration matrix for the transmit and receive array separately, by canceling out the element radiation pattern and effects from the other array through normalization.
UTD-Type Solution of Physical Optics Approximation for Reconfigurable Intelligent Surface Modeled by a Continuous Planar Surface
02 November 2023 Xin Du, Chechia Kang and Jun-Ichi Takada propose a UTD-type solution of the physical optics approximation (PO) for RIS modeled by a continuous planar surface in a two-dimensional environment. The authors validate the proposal under different scenarios in an indoor environment (0.1−20 m) at the terahertz bands (100−300 GHz), by comparing them with those computed using the Fresnel approximation, the Fraunhofer approximation, PO, and the full-wave approach based on the method of moment (MoM). The simulated results show that compared to MoM, the proposal and PO achieve good accuracy with a smaller error of less than 1 dB, while the Fresnel and Fraunhofer approximations present imperfect accuracy with an error of larger than 1 dB in the near-field region.
Increasing the Bandwidth of Wideband Antennas Using the Frequency Pulling Technique
02 November 2023 Anastasios G. Koutinos, Constantinos L. Zekios and Stavros V. Georgakopoulos address the limitation of frequency pulling technique (FPT) by (1) extending FPT to wideband designs, (2) using feeding points located at different planes, and (3) designing feeding networks as unequal power dividers. The networks not only simplify the design complexities associated with the traditional approach but also offer the capability to apply FPT to non-planar designs (e.g., 3D antenna configurations). To demonstrate the latter, they engineer a triangular tapered slot antenna, feeding it with a coupled microstrip line. As a result, the bandwidth of our modeled antenna increases from 34.51% to 78.25%, demonstrating excellent agreement between simulated and measured results.
Electromagnetic Imaging System Calibration With 2-Port Error Models
01 November 2023 Seth Cathers, Joe LoVetri, Ian Jeffrey and Colin Gilmore introduce a novel approach to calibration that models the antennas and field propagation as 2-port networks (rather than scalars or a comprehensive model), for which common network theory and de-embedding techniques can be applied. The accuracy of the proposed 2-port method is experimentally tested against the scalar calibration technique on a 2D imaging system. The use of both metallic and dielectric calibration objects is tested, and the inversion performance is compared for the calibration techniques.
Tuning-Range Extension Strategies for Varactor-Based Frequency-Reconfigurable Antennas
01 November 2023 Quoc Hung Dang, Nghia Nguyen-Trong, Christophe Fumeaux and Shengjian Jammy Chen present tuning range extension strategies for varactor-based frequency-reconfigurable planar patch antennas. The three tuning range optimization methods described in the paper include co-optimization of antenna dimensions and varactor properties, exploitation of multiple radiation modes, and reduction of parasitic capacitance. The first two strategies are emphasized by briefly reviewing two previously reported wide tuning range frequency-agile planar antennas.
Decoupling for Millimeter-Wave Array Antennas Using Near-Field Shrinking Dielectric Superstrate
31 October 2023 Shengyuan Luo, Yiming Zhang, Peng Mei, Gert Frølund Pedersen, and Shuai Zhan propose a decoupling concept of near-field shrinking dielectric superstrate (NFSDS) for large-scale, wideband, and dual-polarized mm-wave arrays. An NFSDS with a thickness of 4 mm ( 0.32λ0 at 24 GHz) is mounted seamlessly above the array, which shrinks the near field of the array elements to reduce the space wave coupling while slightly increasing the surface wave coupling of the arrays. By loading a superstrate with a certain thickness and low permittivity, the total coupling of the mm-wave arrays is reduced significantly.
2 × 2 Lens Array Antenna Using Square-Bottom Concave-Convex Lens in 300-GHz Band
17 October 2023 Bazilah Baharom, Yoshiki Sugimoto, Bakar Rohani, Kunio Sakakibara, Nobuyoshi Kikuma, Yoshihide Yamada and Nurul Huda Abd Rahman proposes a 2×2 lens array antenna composed of square-bottom lenses with a concave-convex lens shaping design to improve the uniformity and aperture efficiency. The measured results of the proposed 2×2 square-bottom concave-convex lens array antenna with a lens height of 9.74 mm achieved a boresight gain of 34.9 dBi, and the lowest sidelobe level observed was greater than −12 dB in the 300-GHz band.
Synthesis of Plane-Wave Generator in 3-D Sphere Quiet Zone for Advanced Antenna Measurement by Hybridizing LSM and GA
11 October 2023 Haidong Chen, Weijun Zhong, Mu Tan, Zhaoling He, Ting Li, Quan Xue and Wenquan Che hybridize the Least Square Method (LSM) and Genetic Algorithm (GA) to efficiently synthesize the linear and planar array Plane Wave Generator (PWG) to create a 3-D Quiet Zone (QZ) with high performance for the antenna pattern measurement in a chamber with limited space. Based on the PWG with an 8-element linear array, the amplitude and phase deviations of 0.89 dB and 14.50° are obtained in a circular QZ with a diameter of 7λ , and that with an 8×8 -element plane array achieves 1.09 dB and 14.89° deviations in a 3-D sphere QZ.
New Analysis and Design Techniques for Arbitrary Reactance Trap Dipoles
05 October 2023 Paul R. Winniford, Adrian L. Bauer, Hjalti H. Sigmarsson and Jessica E. Ruyle present a significantly revised analysis of a classic resonator loaded antenna– the trap dipole. The authors demonstrate in calculation, simulation, and measurement that trap dipoles antennas are not matched or resonant at the same frequency as the trap load resonance. The new analysis unites traditional high impedance trap loads with a wide variety of resonant and reactive loads to achieve multiband antenna performance with quasi-first order field distributions at the operating frequencies.
Impact of 3-D Antenna Radiation Pattern in UAV Air-to-Ground Path Loss Modeling and RSRP-Based Localization in Rural Area
05 October 2023 Sung Joon Maeng, Hyeokjun Kwon, Ozgur Ozdemir and İsmail Güvenç investigate the impact of 3D antenna patterns on a UAV air-to-ground path loss model, utilizing datasets obtained from a measurement campaign. They conducted UAV experiments in a rural area at various fixed heights, while also characterizing the 3D antenna radiation pattern by using an anechoic chamber facility. By analyzing reference signal received power (RSRP) using path loss models that account for antenna patterns, the team observed that the measurement results, obtained at different UAV heights, aligned well with the two-ray path loss model when incorporating the measured antenna pattern.
Low Sidelobe Pattern Synthesis of Array Antennas With a Triangular or Skew Lattice Using the IFT Method
05 October 2023 Will P. M. N. Keizer describes how the present 2D FFTs, direct and inverse, only applicable for rectangular lattices, can be modified in a simple way to make them suitable for the processing signals arranged along a triangular or skew grid. These two modified FFTs are subsequently implemented in the IFT method. The IFT method, updated in this way, is then very suited for the low sidelobe pattern synthesis of array antennas with a triangular lattice or skew lattice.
A Global Optimization Method for Wideband and Small Supergain Arrays Design Using Artificial Neural Network
04 October 2023 Abdellah Touhami, Sylvain Collardey and Ala Sharaiha introduce an efficient approach for compact, wideband and supergain arrays design using artificial neural network (ANN) based optimization. The proposed method optimize at the same time the distance inter-elements of the array antenna, its input impedance as well as its directivity. Such global optimization considerably improves the performances of superdirective arrays in terms of gain, bandwidth and efficiency. The proposed method is used afterwards to synthesize a three-elements array using two different unit elements.
Compact and Broadband Substrate Integrated Dielectric Resonator Antenna Suitable for 5G Millimeter-Wave Communications
27 September 2023 Jie-Er Zhang, Qinfang Zhang, Wei Qin, Wen-Wen Yang and Jian-Xin Chen proposes a compact and broadband substrate-integrated dielectric resonator antenna (SIDRA) suitable for 5G millimeter-wave band applications. Four operating modes from three resonators, including TE111 and TE131 modes from the DR, slot mode from the H-shaped feeding slot, and patch mode from the inserted ring patch, are excited to achieve a bandwidth of 61.9% (24-45.5 GHz) with a compact size of 0.37λ₀0×0.37λ₀×0.125λ₀. The proposed DRA can be extended to an array with ∼0.5λ₀ element interval to obtain wide-angle beam scanning capability.
Equivalent Circuit to Overcome Thévenin Limit for Receiving Lossy Dipole Antennas Motivated by the Poynting Streamline Analysis
27 September 2023 Junming Diao and Lu Liu propose to overcome the limitation of the Thévenin equivalent circuit in determining the loss and scattered powers when dealing with a lossy antenna that is near a large load impedance. They model and analyze the antenna directly as a receiver and visualize the flow of field energy around the antenna through generating streamlines of the Poynting vector field. Motivated by the Poynting streamline analysis, a new equivalent circuit for receiving lossy electric and magnetic dipole antennas is introduced in response to an incident plane wave, which addresses the shortcomings of the traditional Thévenin equivalent circuits.
Compact and Broadband Substrate Integrated Dielectric Resonator Antenna Suitable for 5G Millimeter-Wave Communications
27 September 2023 Jie-Er Zhang, Qinfang Zhang, Wei Qin, Wen-Wen Yang and Jian-Xin Chen propose a compact and broadband substrate-integrated dielectric resonator antenna (SIDRA) suitable for 5G millimeter-wave band applications. Four operating modes from three resonators, including TE111 and TE131 modes from the DR, slot mode from the H-shaped feeding slot, and patch mode from the inserted ring patch, are excited to achieve a bandwidth of 61.9% (24-45.5 GHz) with a compact size of 0.37λ0×0.37λ0×0.125λ0.
Excitation Diversity in Adaptively Thinned Arrays for Microwave Sensing Applications
26 September 2023 Sandra Costanzo and Giovanni Buonanno propose an excitation diversity technique included in thinned arrays design to overcome the unacceptable discrepancy between the actual radiation pattern and the desired one, especially for small to medium-sized arrays, after reducing the complexity of the feeding network. Data distributions achieved with the above approach are averaged to obtain potential high-quality final images. Moreover, the proposed methodology can be easily implemented in real-time adaptive arrays.
Design of Compact and High Isolation Dual-Polarized Antenna Array via Plasmonic Meta-Structure
20 September 2023 Zhang Wen Cheng, Shimeng Wang, Yue Teng Chen, Ji Ran Chen, Jing Cheng Liang, Feng Gao, Shuai Luan, Xin Liu, Hui Feng Ma and Tie Jun Cui propose a compact and high isolation dual-polarized antenna array based on plasmonic meta-structure operating at 2.58 GHz. The compact principle of the dual-polarized antenna is mainly based on spoof surface plasmon polariton (SSPP) radiation patch to support SSPP modes, which is fed by spatially coupled excitation. The cross-polarization coupling between two polarization ports can be improved to below −32 dB, showing high isolation characteristics.
A Quad-Polarization and Beam Agile Array Antenna Using Rat-Race Coupler and Switched-Line Phase Shifter
18 September 2023 Maodudul Hasan, Eisuke Nishiyama and Ichihiko Toyoda propose a quad-polarized microstrip array antenna with beam steering capability. The proposed antenna consists of two patch elements, one rat-race coupler, and two 90° switchable phase shifters. With the aid of just four PIN diodes, the two 90° phase shifters can provide four different diode arrangements for each port of the rat-race coupler. The array elements are excited by using orthogonal feed lines. Due to the combination of the rat-race coupler and phase shifters, different phase conditions are generated between the patch elements or orthogonal modes of the patches.
A Multi-Port Pattern Diversity Antenna With High Isolation
18 September 2023 Nghia Nguyen-Trong and Christophe Fumeaux propose a pattern-diversity antenna with 7 ports for multiple-input multiple-output (MIMO) applications. Orthogonal modes are utilized to achieve high isolation among all 7 ports in a relatively compact shared volume. As distinguishing feature from previous works, the concept of tripolarization is generalized, allowing to design antennas with a large number of orthogonal patterns in a single multi-port device.
Ultra-Wideband Tightly Coupled Dipole Array Fed by a Tapering Meandered Balun
15 September 2023 Matthew W. Nichols, Michail O. Anastasiadis, Malcolm E. Taaffe, Elias A. Alwan and John L. Volakis present an ultra-wideband (UWB) phased array operating from UHF to C-bands (0.14 to 5.85 GHz). This design employs an integrated, compact tapered spline balun in conjunction with a triple-layer semi-resistive frequency selective surface (FSS) network. Notably, the integration of the meandered balun within a dual-polarized tightly-coupled dipole array (TCDA) allowed for a contiguous bandwidth of 40:1 with VSWR < 2.5 at broadside.
Broadband Multi-Shaped Metasurface Circularly Polarized Antenna With Suppressed Non-CP Radiation Modes
13 September 2023 Nathapat Supreeyatitikul, Titipong Lertwiriyaprapa, Nonchanutt Chudpooti, Monai Krairiksh and Chuwong Phongcharoenpanich propose a multi-shaped metasurface broadband circularly polarized (CP) patch antenna with parasitic elements for 5G new radio (NR) applications. The proposed metasurface CP patch antenna comprises triple-layered substrates without air gap. The upper layer sits with multi-shaped metasurface elements and parasitic patches. The middle layer consists of an L-shaped slot functioning as the ground plane, and the lower layer contains a microstrip and a fan-shaped stub functioning as the feed line. The proposed metasurface CP patch antenna with parasitic elements is evaluated using characteristic mode analysis (CMA).
Synthesis of Symmetric, Two-Element Biomimetic Antenna Arrays Using Singular Value Decomposition
04 September 2023 Son Vu, Saeid Jamilan, Barry D. Van Veen, Hung Luyen and Nader Behdad present a method for determining the four-port S-matrix of the external coupling network (ECN) for symmetric, two-element biomimetic antenna arrays (BMAAs) by employing singular value decomposition (SVD). The presented approach greatly facilitates the synthesis procedure of symmetric, two-element BMAAs and allows all possible scattering matrices of a four-port network realizing the ECN to be easily determined.
Efficient Optimization Design of Large Circular Phased Arrays With Low Sidelobes for Beam Scanning
04 September 2023 Yi-Xuan Zhang, Tian-Ye Gao, Li Zhang, Yong-Chang Jiao and Tao Ni propose an efficient optimization design method for large circular phased arrays with low sidelobes for beam scanning. Based on the differential evolution algorithm (DE), each layer’s radius and element number are optimized to obtain the required element arrangement. If the main beam scans from the Z-axis, it is difficult for designers to find the maximum sidelobe.
Low-Cost Hybrid Implementation of an Efficient E-Band Array Based on Stepped and Ridged Slots
01 September 2023 Sherif R. Zahran, Emilio Arnieri, Stefano Moscato, Matteo Oldoni, Dario Tresoldi, Giandomenico Amendola and Luigi Boccia present an 8×8 waveguide antenna array composed of stepped and slotted radiators for E-band applications. The proposed array architecture, including the feeding network, can be realized through the integration of a single metallic block adhered with an additional top photo-etched sheet. This approach effectively reduces manufacturing complexity, resulting in a low-cost solution that can be easily fabricated using standard market-ready technologies.
Multi-Mode Antennas for Ultra-Wide-Angle Scanning Millimeter-Wave Arrays
28 August 2023 Gabriele Federico, Zhe Song, Guilherme Theis, Diego Caratelli and A. Bart Smolders present a novel multi-mode millimeter-wave antenna array with enhanced scan range and reduced scan losses. The individual array element consists of a differentially fed microstrip patch on top of which a cylindrical dielectric resonator is integrated. The radiation pattern of the antenna element can be reconfigured by changing the phase offset between the feeding ports of the patch and the dielectric resonator to excite two distinct radiating modes.
A Dual-Band Dual-Polarized Base Station Antenna Array With Isolation Enhancement
28 August 2023 Lei Ge, Yinhui Wang, Mingye Du, Weiyang Liu and Yue Zhao design a dual-band dual-polarized antenna with isolation enhancement. The proposed antenna operates in the frequency range of 3.4–3.6 GHz and 4.8-5 GHz, where the center frequency of the high band (HB) is 1.4 times that of the low band (LB). Two radiating patches are placed in different layers to create the two distinct resonances and the bottom patch which is shorted to the ground by four metal posts acts as the ground for the top patch antenna. A metal wall is introduced between LB feeding probes to enhance the polarization isolation to more than 25 dB. Complementary split-ring resonator (CSRR) structures are etched on the feedlines to improve the cross-band isolation to over 25 dB.
Near-Field Calibration Methods for Integrated Analog Beamforming Arrays and Focal Plane Array Feeds
11 August 2023 Roel X. F. Budé, Kevin A. P. Van Hastenberg, Ulf Johannsen and A. Bart Smolders propose a near-field calibration method for millimeter-wave analog beamforming array antennas and focal plane array antennas. Nonidealities of the beamformer integrated circuits with vector modulators are taken into consideration, and a way to reduce the measurement set for vector modulators with high resolution is proposed. This method is both practical and achieves a good calibration as evidenced by measurements of the radiation patterns, and it is suitable for use in an automated factory calibration setup.
Coupled Array of Diverse Elements for Wideband High Spherical Coverage
10 August 2023 Quangang Chen, Veli-Pekka Kutinlahti, Jaakko Haarla, Anu Lehtovuori and Ville Viikari propose a flexible cluster array concept utilizing diverse antenna elements and the mutual coupling among them to improve the spherical coverage. This innovative approach can not only enhance the impedance matching but also improve the beamforming performance across a wide frequency band by adjusting excitation amplitudes and phases. Equations are derived to achieve specific objectives such as minimizing the total active reflection coefficient or maximizing the realized gain of an antenna array.
Analysis and Experimental Demonstration of Reflectarray Antennas in Quasi-Regular Lattices
09 August 2023 Borja Imaz-Lueje, Juan Córcoles, Marcos R. Pino and Manuel Arrebola present investigations on reflectarray antennas using non-periodic element distributions. The study involves the analysis and design of two reflectarrays based on quasi-periodic lattices with rectangular and pentagonal profiles, whose performance is compared with equivalent reflectarrays comprised of regular grids of elements. The characterization of these antennas is performed using a tailored analysis technique for reflectarrays with periodical and quasi-periodical grids. The proposed technique uses the Method of Moments under local periodicity conditions (MoM-LP) to compute the field on the surface of each cell and then the far field radiated by the aperture.
Shared Impedance Noise Coupling in Radio Receivers
08 August 2023 Yihong Qi and Yunlong Luo elucidates a shared impedance noise coupling mechanism, which sheds light on how passive antennas can introduce excess noise into the wireless system. This article introduces the general theory of antenna noise temperature, providing an explanation for the mechanism of noise coupling through a shared impedance path. Additionally, a mathematical expression for radiated sensitivity is presented.
Uncertainty Analysis Methodology for Measurements of Dynamic Millimeter-Wave Channels
01 August 2023 Robbert Schulpen, A. Bart Smolders, Ulf Johannsen, and L. A. Bronckers present a novel uncertainty analysis methodology to quantify uncertainties of condensed parameters in measurements of dynamic millimeter-wave channels. The bandwidth limitation and multipath threshold are identified as important impairments. Therefore, the methodology provides three uncertainty metrics for condensed parameters, namely a standard uncertainty to quantify the impact of random variations; a bias due to the multipath threshold; and a total bias including the impact of the bandwidth limitation.
End-to-End Channel Modeling and Generation Software Based on Statistical mmWave Channel Model
28 July 2023 Yusuke Koda, Ruiting Ouyang and Hiroshi Harada develop an end-to-end software to automatically perform channel modeling and simulation with statistical validity just by inputting measured power profiles. The developed software involves comprehensive algorithms to reach channel parameter extraction, such as multi-path component (MPC) extraction, MPC clustering, and maximum-likelihood estimations for respective parameters. They highlight that channel parameters reported by the IEEE 802.15.3c task group (TG) do not necessarily fit the original power profiles, highlighting the need to examine the validity of the existing parameters by leveraging the developed software.
Design of a Compact 4-Element GNSS Antenna Array With High Isolation Using a Defected Ground Structure (DGS) and a Microwave Absorber
25 July 2023 Abdullah Madni, and Wasif Tanveer Khan presents a compact (125 mm diameter) wideband 4-element antenna array with a high isolation level for global navigation satellite system (GNSS) applications. The array consists of four right hand circularly polarized (RHCP) single feed rectangular patch antennas that can cover BeiDou B1 band (1561.098 MHz), GPS L1 band (1575.42 MHz), Galileo E1 band (1575.42 MHz) and GLONASS G1 band (1602 MHz) of the GNSS upper L-band (1559 - 1610 MHz). The proposed array has a wide frequency bandwidth of 80 MHz with an axial ratio of less than 3 dB. The patch elements are designed on a substrate which has a high dielectric constant to achieve a compact size.
A Study on mm-Wave Propagation in and Around Buildings
20 July 2023 Leonardo Possenti, Marina Barbiroli, Enrico M. Vitucci, Franco Fuschini, Mattia Fosci, and Vittorio Degli-Esposti analyze in depth the peculiar characteristics of mm-wave propagation, joint measurement and simulation campaigns in indoor and outdoor microcellular environments. The investigation highlights that the assumption that mm-wave NLoS connectivity is hardly feasible is not necessarily true as significant reflections, scattering and even transmission mechanisms can provide good NLoS coverage in the considered indoor and outdoor scenarios. This is also reflected in the limited angle-spread differences between LoS and NLoS locations in some cases.
Dual-Port RHCP Compact Antenna at 868 MHz Using a 120° Hybrid Coupler
19 July 2023 Fabien Ferrero, and Le Huy Trinh present the design of a compact dual-port circularly polarized antenna based on the new coupler topology. The antenna can radiate a right-hand circular polarization (RHCP) in two opposite directions depending on the input port. In the proposed structure, the radiating system has three inverted F antennas connected to a 120° hybrid coupler. The modeling and design of the 5-ports hybrid coupler are described and experimentally validated.
Wide-Angle Beam Scanning Phased Array Antennas: A Review
18 July 2023 Ming Li, Shu-Lin Chen, Yanhui Liu and Y. Jay Guo investigate and discuss several challenges that hinder wide-angle beam scanning (WABS) for conventional phased array antennas (PAAs), including the strong mutual coupling, narrow beamwidth of the element antenna, etc. We then review and summarize a variety of innovative techniques to overcome these challenges. Subsequently, we discuss and analyze potential research gaps of WABS PAAs for future emerging applications.
Compact U6G Massive MIMO Antenna Arrays With Double-Layer Partial Reflective Decoupling Layers for Mutual Coupling Suppression
18 July 2023 Ting Liu, Jiayue Jiang, Luyu Zhao, Ge Zhao, Huiqing Zhai, Yuan-Ming Cai, Teyan Chen, and Wenwei Xu utilize a systematic decoupling strategy of two partial reflective decoupling layers (PRDLs) and dummy decoupling probes (DDPs) to suppress the complicated couplings in a ±45° dual-polarized, compact antenna array operating at Upper 6 GHz (U6G, 6425–7125 MHz) bands. Finely engineered neutralization electromagnetic waves are introduced by two PRDLs to counteract the original couplings. Two layers of PRDLs are placed above the antenna array in a step-by-step manner to gradually cancel out several major couplings while DDPs are placed around the antenna elements to reduce the remaining couplings.
Wide-Angle Beam Scanning Phased Array Antennas: A Review
18 July 2023 Ming Li, Shu-Lin Chen, Yanhui Liu, and Y. Jay Guo investigate and discuss several challenges that hinder wide-angle beam scanning (WABS) for conventional phased array antennas (PAAs), including the strong mutual coupling, narrow beamwidth of the element antenna, etc. in this review. They then review and summarize a variety of innovative techniques to overcome these challenges, and analyze potential research gaps of WABS PAAs for future emerging applications.
A 3-D Printed Ultra-Wideband Achromatic Metalens Antenna
17 July 2023 Yu-Xuan Xie, Geng-Bo Wu, Wen-Qiang Deng, Shu-Yan Zhu and Chi Hou Chan propose a millimeter-wave achromatic metalens antenna using three-dimensional (3D) printing technology to reduce the dispersion effect and enlarge its bandwidth. The proposed ultra-wideband achromatic metalens antenna consists of a convex-liked metalens (VLM) and a concave-liked metalens (CLM) integrated as a metalens group. The VLM is designed on the basis of dielectric posts with different heights. The calculated transmission phase (from 0 to 2π ) of VLM can be realized by changing the height of dielectric posts.
Airborne Reflector-Based Ground Penetrating Radar for Environmental and Archaeological Studies
17 July 2023 Zayed Mohammad, and Andrew M. Chrysler design and propose a wideband airborne reflector-based ground penetrating radar (GPR). It consists of 15 discrete panels, each panel supported by a single multi-rotor unmanned aerial vehicle (UAV). A lightweight, wideband Vivaldi antenna was developed as the feed structure. The antenna operates within the frequency range of 100–500 MHz and has a bandwidth of 387 MHz. The proposed antenna will possess a penetration depth of 2 m.
Feed Integration and Packaging of a Millimeter-Wave Antenna Array
17 July 2023
Matthew W. Nichols, Stavros Koulouridis, Satheesh B. Venkatakrishnan, Elias A. Alwan, and John L. Volakis present and demonstrat a novel approach for integrating a wideband vertically fed antenna array at Millimeter-Wave (mm-Wave) frequencies. Specifically, a novel cost-effective Antenna-In-Package (AiP) fabrication approach is presented, then a prototype operating from 55 GHz to 64 GHz is built while predicted performance is verified via measurements. This approach relies on separating fabrication into
1. the array and
2. the back-end feeding board.
Assembly of the various components is achieved through several precision microfabrication steps utilizing a Ball-Grid-Array (BGA) technology with thermally stable conductive solder paste.
A 3-D Printed Ultra-Wideband Achromatic Metalens Antenna
17 July 2023 Yu-Xuan Xie, Geng-Bo Wu, Wen-Qiang Deng, Shu-Yan Zhu, and Chi Hou Chan propose a millimeter-wave achromatic metalens antenna using three-dimensional (3D) printing technology to reduce the dispersion effect and enlarge its bandwidth. The proposed ultra-wideband achromatic metalens antenna consists of a convex-liked metalens (VLM) and a concave-liked metalens (CLM) integrated as a metalens group.
A Technique to Realize Aperture Coupled Microstrip Patch as a Truly Low Cross-Polar Antenna by Mitigating the Major Issues Over its Skewed Radiation Planes
14 July 2023 Sk Rafidul, Chandrakanta Kumar, and Debatosh Guha address and resolve the limitation of the low cross-polarized (XP) radiations of aperture-fed microstrip patch by introducing a pair of additional printed loops adjacent to the radiating patch.Detailed investigations leading to the design insight have been presented. A C-band rectangular patch promises as much as 7 dB suppression in the diagonal plane XP level keeping the overall performance across the principal radiation planes unchanged.
Antenna Design for the Arctic Weather Satellite Microwave Sounder
14 July 2023 Roland Albers, Anders Emrich, and Axel Murk propose an antenna design for the Arctic Weather Satellite (AWS), a prototype mission for an operational constellation of microwave sounders, complimenting existing meteorological sounders. The AWS is a microsatellite with a single cross-track scanning radiometer operating in the 54, 89, 183 and 325 GHz bands. Due to the small platform size, the core design focus of the radiometer’s quasi-optics is less complexity and a more compact setup than comparable spaceborne microwave sounders. The main challenge for instrument performance is that only one of the four horns can be located in the focus of the scanning reflector. Consequently, scan angle dependent spillover variations and beam asymmetries can occur. This paper details the simulation and optimisation efforts of the quasi-optics to minimise the aforementioned effects.
Tuning the Angular Characteristics of Biomimetic Antenna Arrays
11 July 2023 Ines Dorsch Dominik Schwarz, Sarah Forster, and Christian Waldschmidt present the concept and the design process of a tunable Biomimetic Antenna Arrays (BMAA). By electronically tuning varactor diodes, such an array can adapt its angular characteristics depending on the direction-of-arrival (DoA) and signal strength of a radar target. The theoretical requirements for the desired task are examined with general S-parameter simulations. Extensive circuit simulations of a proposed architecture unveil a variety of achievable designs of tunable BMAAs. Radar measurements of different implementations in the 77 GHz range and the theoretical analysis are in good agreement.
Receive Mode Time-Modulated Antenna Array Incorporating Subsampling—Theoretical Concept and Laboratory Investigation
07 July 2023 Edward A. Ball, Sumin David Joseph and Alan Tennant present an eight element Subsampling Time Modulated Array (STMA) operating in receive mode with a carrier at 2.4 GHz using bespoke Radio Frequency (RF) hardware. Each STMA cell incorporates subsampling functionality, with the sampling frequency significantly below the carrier frequency and requiring minimal additional hardware. By using this concept, the hardware required for a receiver incorporating an antenna array can be reduced and costs saved. STMA design equations and architecture strategies are presented, and a prototype hardware demonstrator is introduced.
A Dual Wide-Band Mushroom-Shaped Dielectric Antenna for 5G Sub-6-GHz and mm-Wave Bands
05 July 2023 Reza Shamsaee Malfajani, Hamed Niknam, Sampada Bodkhe, Daniel Therriault, Jean-Jacques Laurin and Mohammad S. Sharawi present the design and implementation of a dual wide-band mushroom-shaped antenna. The antenna consists of a cylindrical dielectric resonator (cDRA), a cylindrical dielectric rod as a waveguide (cDR), and a dielectric lens (DL). The cDRA in conjunction with the DL acts as a sub-6-GHz antenna. At the mm-wave band, the small cDR acts as a waveguide, which transfers the wave from the feed toward the larger cDRA and the DL in order to produce a high gain.
A Diffusion Model for Multi-Layered Metasurface Unit Cell Synthesis
04 July 2023 Chen Niu, Mario Phaneuf, and Puyan Mojabi propose a deep learning approach based on a diffusion model to yield metasurface unit cell designs. This method takes desired two-port scattering parameters along with the frequency of operation in an attempt to synthesize three-layered metasurface unit cells. The core of this approach lies in casting the three-layered unit cell synthesis process as conditional three-channel binary image synthesis. The conditions are governed by the desired scattering parameters at a given frequency whereas the binary nature implies the presence and absence of metallic traces.
A Deep Learning-Based Approach to Design Metasurfaces From Desired Far-Field Specifications
04 July 2023 Chen Niu, Mario Phaneuf, Tianke Qiu and Puyan Mojabi develop a deep learning neural network model in conjunction with a method to incorporate auxiliary surface waves for the macroscopic design of transmitting metasurfaces. The main input to the neural network model is the user-defined desired far-field specifications. This network is used to calculate the required tangential electromagnetic fields on the metasurface. These fields will then be augmented by incorporating auxiliary surface waves along the metasurface for power redistribution to satisfy the requirement for having lossless and passive metasurfaces.
Statistical Evaluation of the Role of GNSS Signal Propagation Orientation in Low-Latitude Amplitude Scintillation Severity
30 June 2023 Alison Moraes, Jonas Sousasantos, Bruno J. Affonso, Paulo R. P. Silva, Eurico R. De Paula and João F. G. Monico perform an analysis considering aspects of the orientation of the propagation of the radio signals through the plasma bubbles structures to evaluate how this geometry can affect the scintillation profile. The dataset covers five months of records from three stations over the Brazilian region during the last solar cycle maximum. The initial results indicate that propagation paths fully aligned are consistently related to larger values of S4 and more severe scintillation.
Physics-Based Coherent Modeling of Long-Range Millimeter-Wave Propagation and Scattering in Rain
12 June 2023 Behzad Yektakhah and Kamal Sarabandi present a fast and accurate numerical method for phase coherent modeling of wave propagation and scattering in random media, like rain. In this approach, the random medium is divided into sufficiently large finite slabs and each slab is modeled as a network with multiple input/output ports where ports represent rays with different polarizations propagating in different directions entering and leaving the slabs. The proposed method considers multiple scattering among all scatterers and thus the entire physics of wave-particle interactions is accounted for.
Bandwidth Enhancement of Low-Profile Metasurface Antenna Using Nonuniform Geometries
08 June 2023 Hayden A. Banting and Carlos E. Saavedra investigate artificial magnetic conductor metasurface antennas using a robust, surrogate-assisted, differential evolution optimization technique. Using a uniform metasurface array configuration as a starting point, multiple array configurations are parameterized and the differential evolution optimizer yields nonuniform array geometries exhibiting wideband performance. Two prototypes are fabricated and characterized to experimentally confirm the advantages of proposed designs.
Post-Fabrication Technique to Manage Material Variations in 3-D Printed Microstrip Antenna Substrates
08 June 2023 Zere Iman, Zubair Akhter, Yiyang Yu and Atif Shamim present a post-fabrication technique capable of compensating for variations in the εr of 3D printed substrates, focusing on microstrip patch antennas (MPAs). The proposed technique, suitable for correcting the fr of a single microstrip patch antenna, uses either a single blind via or an array of vias in the 3D-printed substrate. Two MPAs were fabricated on a 3D-printed substrate and it is shown that their fr values can be shifted upward or downward by following the proposed guidelines.

3D Printed Hemispherically Radiating Antenna for Broadband Millimeter Wave Applications
23 May 2023 Lukas Engel, Danti Khouri, Konstantin Lomakin, Andreas Hofmann, Micha Kleinlein, Ingrid Ullmann, Martin Vossiek, and Gerald Gold present a 3D printed monolithic antenna for millimeter wave-sensing applications with a full hemispherical coverage. The antenna is designed as an ensemble of a waveguide horn antenna and a differentially fed dipole antenna. The slotted waveguide approach was utilized to improve the manufacturing quality on the waveguide inside.
Reflectarray Feeds Augmented With Size-Reducing GRIN Lenses for Improved Power Handling and Aperture Efficiency
19 May 2023 Eric B. Whiting, Galestan Mackertich-Sengerdy, Ryan J. Chaky, Colin A. Mussman, Sawyer D. Campbell, Pingjuan L. Werner, and Douglas H. Werner demonstrate highly effective approaches for optimizing GRIN lenses to achieve different design objectives including high gain radiation with a compact feed as well as improved aperture efficiency and power handling. Additive manufacturing is employed to fabricate the lenses, and measured results agree well with simulations.
Analytic Approximation of In-Body Path Loss for Implanted Antennas
15 May 2023 Mingxiang Gao, Zvonimir Sipus, and Anja K. Skrivervik present a simplified model of an implanted antenna that provides closed-form approximate expressions to estimate EM radiation from the implant. In particular, they extend the expressions for the reactive near-field losses to both deep and shallow implants, by taking into account the implantation depth.n The proposed approximate method is verified by comparing the results obtained with the full-wave simulations in the case of a miniature implanted antenna, and with both simulated and measured results from two practical examples found in the literature.
3-D Printable Synthetic Metasurface to Realize 2-D Beam-Steering Antenna
10 May 2023 Foez Ahmed, Touseef Hayat, Muhammad U. Afzal, Shiyu Zhang, Karu P. Esselle, and William G. Whittow present highly radio-frequency (RF) transparent phase gradient synthetic metasurfaces made of sub-wavelength-sized 3D printable meta-atoms with tailored permittivity that cannot be achieved with off-the-shelf, commercially available materials. The synthesized meta-atoms design uses one dielectric block of PREPERM ® ABS 1000 material with air and metallic inclusions to make low- and high-permittivity materials. The inclusions’ size and height are varied to achieve a complete phase range from 0 to 360°, while maintaining transmission magnitudes greater than −3.0 dB.
A 3D-Printed Encapsulated Dual Wide-Band Dielectric Resonator Antenna With Beam Switching Capability
09 May 2023 Reza Shamsaee Malfajani, Hamed Niknam, Sampada Bodkhe, Daniel Therriault, Jean-Jacques Laurin, and Mohammad S. Sharawi present the concept of encapsulated dielectric resonator antennas (E-DRAs). In E-DRAs, smaller-sized DRAs with a specific permittivity is embedded inside a larger DRA with a lower permittivity allowing for simultaneous efficient radiation at two widely separated and widely covered frequency bands. The proposed E-DRAs cover both the sub-6-GHz band (with a large size DRA) and mm-wave band (with smaller sized DRAs) for 5G and beyond applications.
3-D Printed All-Dielectric GRIN Lens Antenna With an Integrated Feeder
05 May 2023 Anastasios Paraskevopoulos, Francesca Maggiorelli, Ilir Gas Hi, Cristian Della Giovampaola, Matteo Albani, Stefano Maci present the design, fabrication, and experimental verification of a new type of Graded-index (GRIN) lens antenna with an integrated feeder. The continuously varying refractive index distribution is chosen appropriately to offer the rays collimation at the lens aperture. It is practically implemented by varying the material density in a host medium, thus realizing a new type of all-dielectric high gain antenna, entirely using 3D printing. This solution can find application to high gain wireless communication and measurement systems.
Fully Printed 3-D Antennas With Wideband Radiation Isotropy Based on Annular Currents Models
02 May 2023 Ruiqi Wang, Kirill Klionovski and Atif Shamim propose a theoretical model based on annular ring currents to synthesize quasi-isotropic antenna radiation patterns. The theoretical model shows that wideband radiation isotropy can be achieved by optimizing the combination of azimuthal currents. We subsequently present spherical and cubical ESA designs that achieve measured wide impedance and radiation isotropy bandwidths exceeding 10% for the GSM900 band.
Circularly-Polarized Patch Antennas With Enhanced Bandwidth Based on Capacitively Coupled Orthogonal Patch Radiators
02 May 2023 Qiong-Sen Wu, Xiao-Yu Tang, Xiao Zhang, Lei Zhu, Gary Zhang and Chun-Bing Guo propose circularly-polarized (CP) patch antennas with enhanced bandwidth based on capacitively coupled orthogonal patch radiators Several patch radiators are alternately arranged one by one along the x - and y -direction, producing orthogonal currents and far fields. The adjacent patch radiators are coupled to each other and the coupling structure not only contributes to power distribution but also introduces 90° phase shift for circularly-polarized radiation.
A Concept of Advanced Design Governed by Theoretically Predicted Current Distributions on the Ground Plane Beneath an Aperture-Fed Microstrip Antenna
02 May 2023 Debi Dutta, Debatosh Guha and Chandrakanta Kumar explore a way of mitigating near field issues based on theoretical analysis and propose a simple strategic approach to reform the same for a rectangular patch. A representative design, theoretical justification, and experimental studies with an S-band prototype have been presented. XP suppression by 11dB has been experimentally achieved in the diagonal (D-) plane with no considerable changes in its H- or E-plane. That eventually attains an overall XP discrimination by nearly 27dB from the perspective of 3D radiation scenario.
Uniform Analysis of Multipath Components From Various Scenarios With Time-Domain Channel Sounding at 300GHz
02 May 2023 Johannes M. Eckhardt, Alper Schultze, Ramez Askar, Tobias Doeker, Michael Peter, Wilhelm Keusgen, and Thomas Kürner present a uniform and collaborative data evaluation of measurement sets from two different time-domain channel sounders. The channels show a great variety of characteristics depending on the scenario, the line-of-sight condition and the signal-to-noise ratio requirements of the prospective communication system. The extracted multipath components are published as research data for future analytical studies and simulations in relevant scenarios for the sixth generation of mobile systems.
Planar Array Subarray Division Method in Microwave Wireless Power Transmission Based on PSO&K-Means Algorithm
27 April 2023 Qian He Zhang and Zhao Yang Shen propose a clustering algorithm based on a combination of the particle swarm algorithm and the K-means algorithm for the subarray partitioning of planar arrays to address the problem of maximizing beam collection efficiency in microwave wireless power transmission. The effectiveness of the proposed method is evaluated by integrating the beam collection efficiency with parameters such as the receiving area and the size of the planar array.
Indirect Applications of Additive Manufacturing for Antennas
10 April 2023 Jonathan D. Lundquist, Lauren Linkous, Umar Hasni, and Erdem Topsakal report the fabrication methodology of stereolithography (SLA) printed molds for metal and resin cast antennas. In the first method, a conical horn created using metal cast molds printed from a glass-filled resin utilizes a casting technique allowing for low-cost 3D printing to fabricate metal antennas. The second casting method demonstrates the interchangeability between creating parts via SLA printing with a glass-filled resin and using the same resin cast into a reusable Polydimethylsiloxane (PDMS) mold.
3-D-Printed Spiral Leaky Wave Antenna With Circular Polarization
05 April 2023 Tomás Lira-Valdés, Eva Rajo-Iglesias, and Francisco Pizarro present the design, manufacturing and measurement of a fully dielectric leaky wave antenna operating at 18 GHz. The antenna is composed of a grounded dielectric substrate with a top dielectric Archimedean spiral corrugation, which allows obtaining a directive pencil-beam in broadside direction with circular polarization depending on the turning sense of the spiral.
3-D Printed Dually Symmetric Orthomode Transducer and Horn Antenna at X-Band
03 April 2023 Ian Goode, and Carlos E. Saavedra present a dually symmetric orthomode transducer (OMT) and horn antenna for both single port linearly polarized operation and dual port circular polarization use. The feed uses two waveguide splitters and a feed bend to feed a four-port horn antenna that has the two groups of ports orthogonal to each other to produce a symmetric radiation pattern. The feed is printed from 316L stainless steel while the horn is printed from a plastic polymer and metallized using aluminum tape.
Practical Correlation-Matrix Approaches for Standardized Testing of Wireless Devices in Reverberation Chambers
30 March 2023 Kate A. Remley, Sara Catteau, Ahmed Hussain, Carnot L. Nogueira, Mats Kristoffersen, John Kvarnstrand, Brett Horrocks, Jonas Fridén, Robert D. Horansky, and Dylan F. Williams extend the autocorrelation-based approaches currently used in standards to full correlation-matrix-based approaches in order to identify correlation between both spatially adjacent and non-adjacent samples in reverberation-chamber measurements. They employ a scalar metric that allows users to identify the number of effectively uncorrelated samples in new types of stirring sequences.
Systematic Design Method for Mutual Coupling Reduction in Closely Spaced Patch Antennas
28 March 2023 Hui Deng, Lei Zhu, and Zhao-An Ouyang present a systematic design approach to reduce the mutual coupling between a pair of closely spaced microstrip patch antennas (MPAs). This method can effectively overcome the main drawback of previous two-path cancellation methods, i.e., lack a systematic design guideline and heavily rely on the time-expensive trial-and-error procedure to mitigate mutual coupling in a best-effort manner. They propose the concept and workflow of the systematic design method, and introduce the circuit-level modeling upon the proposed two coupling routes.
Angle-Dependent Synthesis Method for Holographic Multi-Feed Antennas
27 March 2023 Thomas Frey, Maximilian Döring, Nico Riese, Christian Waldschmidt, and Tobias Chaloun present a novel synthesis method for holographic multi-feed antennas to combine all sub-holograms into an angle-dependent shared holographic aperture. In order to find the global error minimum between the shared holographic aperture and all ideal sub-holograms, a non-pixel-based genetic optimization is used. For a more accurately implementation of the analytical impedance tensor an eigenvector approach taking all tensor components into account is introduced.
Additive Manufacturing of Linear Continuous Permittivity Profiles and Their Application to Cylindrical Dielectric Resonator Antennas
16 March 2023 Simon P. Hehenberger, Stefano Caizzone, and Alexander G. Yarovoy consider the utilization of additive manufacturing (AM) to engineer the permittivity profile of dielectric resonator antennas (DRAs). The capabilities of AM are exploited to create continuously swept permittivity profiles and applied to cylindrical DRAs. The spatial variant lattices (SVL) synthesis algorithm is implemented to create the desired permittivity profiles from a single material, and resulting geometries are manufactured using a high-permittivity material in a fused deposition modeling AM process.
Additively-Manufactured All-Dielectric Microwave Polarization Converters Using Ceramic Stereolithography
15 March 2023 Steve M. Young, Mark Kauf, Jeffrey Kutsch, and Anthony Grbic report a class of all-dielectric, additively-manufactured polarization converters with tailored temporal frequency responses within the Ku and Ka microwave bands (15– 40 GHz). These multi-layer devices consist of cascaded, subwavelength, high-contrast gratings with different fill fractions and orientations, providing control over the effective anisotropic properties of each layer. Three example devices based on alumina/air gratings have been monolithically fabricated using ceramic stereolithography: a broadband reflective half-wave plate, a broadband isotropic polarization rotator, and a dual-band linear-to-circular polarization converter.
Highly Efficient Calibration of Antenna Arrays by Active Targets in the Near-Field
08 March 2023 Matthias Linder, Benedikt Meinecke, Enes Halici, Dominik Schwarz, and Christian Waldschmidt propose a calibration setup employing active calibration targets (ACT) to reduce the calibration effort, hereby defined as the number of required measurements. The setup allows the storage of a multitude of data points within a single measurement. It is placed in the near-field of the array to relax the requirements on the size of the anechoic chamber. Employing multiple targets makes it challenging to compensate for the near-field effects.

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