Frequency-Unconstrained High-Realizability Design of a Dual-Band Harmonic-Controlled Rectifier Based on Branch-Line Coupling Structure

This paper presents a novel methodology for designing a high-efficiency dual-band (DB) rectifier with harmonic control characterized by simple realizability and high flexibility of frequency. The proposed structure features two distinct rectifier branches, each intentionally optimized to operate at a specific frequency while being blocked at the other using only basic single-band functional circuits. The branches are power excited through one of the two coupling ports of a DB branch-line coupler. Optimal power distribution for each sub-rectifier is achieved through the coupler’s reflection mechanism. Specifically, the isolation port is grounded, which partially re-injects the reflected power from the two subrectifiers due to impedance mismatch. This power is reused to achieve optimal power conversion efficiency (PCE), thus addressing issues such as frequency limitations and low design feasibility. For validation, a rectifier operating at two target frequencies with an integer relation of (f₂ = 2f₁), i.e., f₁ = 0.915 GHz and f₂ = 1.83 GHz, was designed. It attained a measured peak PCE of 77.4% and 77.1% at 0.912 GHz and 1.866 GHz, respectively, indicating optimal PCE performance at a pair of frequencies that is constrained in conventional approaches.