Ultra-Wideband Rectenna Using Complementary Resonant Structure for Microwave Power Transmission and Energy Harvesting

An ultra-wideband (UWB) rectenna (fractional bandwidth >100%) using a novel wideband complementary matching stub is proposed for microwave power transmission and energy harvesting. A simple resonant structure, i.e., LC series-parallel resonant circuit, is embedded to the L-shaped complementary matching stub. Due to the unique frequency response of the LC resonant circuit, the proposed matching stub can exhibit “open” and “short” circuits as a function of frequency, thereby acting as a complementary matching circuit covering a relatively wide frequency range. Having utilized the proposed matching stub, the nonlinear input impedance of the rectifier can be tuned to conjugately match the antenna impedance throughout the frequency band of interest. Simulated and measured results show that the proposed rectenna has good matching performance ( S
₁₁
<; -10 dB) and high RF-dc conversion efficiency (>50%) over a relatively wide frequency range from 0.9 to 3 GHz (for GSM, Wi-Fi, and WLAN bands). The maximum conversion efficiency of 73.4% is realized at 3-dBm input power. It is evident that the proposed resonant structure-based matching scheme is a promising and effective solution to facilitate the UWB rectenna design with stably high efficiency over a very wide frequency band.