Battery-Free Intelligent Systems: RFID, Backscatter Communications, Wireless Sensing and RF Energy Harvesting

Battery-free wireless systems have attracted significant attention in recent years due to advances in antennas and propagation, radio-frequency identification (RFID), backscatter communication, RF energy harvesting, wireless power transfer (WPT), and low-power sensing. These systems enable sensing, identification, localization, and communication without conventional batteries, offering a practical solution for large-scale deployments where battery replacement and maintenance impose significant cost and operational constraints. Electromagnetic energy is the basis of battery-free operation, where antennas capture, radiate, and manipulate RF power. Propagation conditions determine the availability of RF energy and the reliability of communication links. RFID and backscatter systems use electromagnetic waves for both power delivery and information transfer, resulting in strong coupling among antenna characteristics, propagation environments, circuit operation, and system performance. Consequently, advances in antenna design, propagation modeling, scattering analysis, rectifying structures, and wireless power transfer directly influence communication range, RF-to-DC conversion efficiency, sensing capability, and network scalability.

Recent research has expanded the scope of battery-free technologies beyond conventional RFID platforms. Chipless RFID, computational RFID, ambient backscatter communication, rectennas, self-powered sensors, distributed wireless power transfer, integrated sensing and communication (ISAC), and intelligent electromagnetic structures continue to expand the capabilities of energy-autonomous systems. At the same time, these developments introduce important challenges related to antenna–rectifier co-design, propagation aware optimization, multiband operation, low-power sensing, electromagnetic characterization, and large-scale deployment in complex environments. This Special Section seeks contributions that advance the theory, design, implementation, and applications of battery free intelligent systems. The Section places particular emphasis on antenna and propagation aspects of RFID technologies, backscatter communication, RF energy harvesting, wireless power transfer, rectennas, and self-powered sensing platforms. Contributions addressing fundamental electromagnetic principles, novel antenna architectures, propagation studies, circuit and system integration, experimental validation, and practical applications are particularly encouraged.

This Special Section will bring together researchers from the antennas and propagation, microwave engineering, RFID, wireless power transfer, and sensing communities and will highlight recent advances that support the development of next-generation energy-autonomous wireless systems.