Haoming He, Chongwei Liao, Zhongqi He, Liping Yan, Changjun Liu
Harmonic control is an efficient design method to improve the efficiency of a microwave rectifier. Conventional class$F$and${F} ^{-1}$microwave rectifiers achieve high efficiencies by harmonic control. However, the working bandwidth is limited since the harmonics generated during rectification have to be strictly controlled. This article presents a method to design a microwave rectifier that adaptively switches between class$F$and${F} ^{-1}$with respect to frequency variations by a harmonic control network. A broadband rectifier is designed with an efficiency higher than 70% from 1.54 to 2.66 GHz at 11-dBm input power. Extending the method to apply more harmonic termination switches, another ultrawideband rectifier is designed, fabricated, and measured. The ultrawideband rectifier maintains a rectification efficiency higher than 70% over the frequency range from 1.0 to 3.1 GHz. The design and measurement results of both rectifiers verify the high efficiency and effectiveness of the proposed adaptive method of harmonic control, which successfully breaks the frequency limitation of conventional harmonic terminal control. The design can be applied to wireless power transfer and energy harvesting.