Compact IoT Wireless Charging System with Impedance Matching Elimination

In this paper, a dual-band metasurface-structured antenna is designed to eliminate the need for a complex impedance matching network. The antenna excites the fundamental TM10 and higher-order $\mathbf{TM}_{20}$ modes, operating at 2.1 GHz and 2.45 GHz, respectively. Integrating the rectifier circuit, the rectenna demonstrates the peak RF-to-DC conversion efficiencies of 60.1% at 2.1 GHz and 60% at 2.45 GHz. The most significant advantage of this design is eliminating the complex impedance matching network, resulting in a compact, simple, cost-effective and high-efficiency rectenna. The major contribution lies in exploring how metasurface antenna parameters influence the real and imaginary parts of impedance matching. This type of antenna is particularly suitable for low-power sensor charging applications like forest fire monitoring and medical devices powering. Measurement results closely match the simulation results, validating the effectiveness of the design.