Waveguide-ring resonator coupler with class-F rectifier for 2-D waveguide power transmission

In this paper we demonstrate a high-efficiency dc power extraction using a rectifying coupler in a two-dimensional waveguide power transmission (2DWPT) system. In our recent research, 2DWPT system has been improved in efficiency and electromagnetic compatibility (EMC), by covering the waveguide surface with a thick insulator layer and using a high-quality-factor (high-Q) resonant coupler. The rectifying coupler is a combination of a high-Q waveguide-ring resonator (WRR) coupler and a class-F rectifying circuit. We evaluate the overall efficiency, i.e. the ratio of the dc output of the rectifying coupler to the RF input into the sheet, in a prototype 2DWPT system. A 6.4 × 3.6 cm² coupler on a 56 × 39 cm² sheet (nearly 100 times larger area than the coupler) achieved 40.4% efficiency at a maximum, where the RF input was 30.0 dBm in a 2.4-GHz band.