High Efficiency of Rectifier Circuit for WiCoPT utilizing Doubly Asymmetrical Branch-Line Coupler

In the paper, improvement of the efficiency for the Rectenna (Rectifier + Antenna) is described. The rectifier circuit in this research promotes further improvement in efficiency and expansion of the power range by using the passive path switching method that can be shifted according to the frequency band. In the previous research, the circuit was configured by using the conventional branch-line coupler as a power divider, however the conversion efficiency on the low power region was not so good. Therefore, in this research, the circuit is configured by using the doubly asymmetrical branch-line coupler to widen the impedance difference at the output ports. As a result, it was confirmed by using an electromagnetic simulation (AWR AXIEM) that the conversion efficiency at low power region was improved up to 65.8%, which was about twice that of the conventional one. In addition, it is verified experimentally as well as analyzed.