A Self-Biased Adaptive Reconfigurable Rectenna for Microwave Power Transmission

A self-biased adaptive reconfigurable rectenna, consisting of a microstrip patch antenna and a self-biased reconfigurable rectifying circuit, is proposed in this letter. To eliminate the need of bias networks, a dc power routing structure is introduced to link the reconfigurable matching stub and the load. Hence, the output dc current obtained by the rectifier can be divided/split, thereby letting a part of the dc current flow back to the matching stub for providing a bias voltage. According to the input power level, the states of the p-i-n switch can be automatically changed in order to connect/disconnect the matching stub to the rectifying circuit for achieving improved matching performance at different power levels. Simulated and measured results show that the proposed rectenna reaches more than 50% conversion efficiency over a broadened input power range from 0-20 dBm with the peak efficiency of 68% at 9 dBm. It is evident that the proposed self-biased reconfigurable matching scheme is a promising and effective solution to facilitate the less-complicated reconfigurable rectenna integration and realize high efficiency at higher operating frequency bands (e.g., >5 GHz).