Compact ultra-wideband rectifier for environmental energy harvesting based on coupled structure

This paper presents a compact, ultra-wideband, and high-efficiency rectifier designed for microwave power transmission and energy harvesting applications. The proposed architecture integrates a series-coupled matching network with cascading band-stop structures, enabling both impedance transformation and harmonic control within a compact footprint. Two highly compact rectifiers are designed, fabricated, and measured to verify the proposed method. A broadband rectifier, operating between 1.8 and 3.0 GHz with a relative bandwidth of 50%, achieves above 70% rectification efficiency and a peak efficiency of 79%. The other wideband operation mechanism is analytically investigated: the band-stop network reshapes the diode’s impedance profile by tuning its low- and high-frequency components into a conjugate relationship, while the coupled matching structure transforms the resulting impedance to match the system impedance, thereby realizing ultra-wideband matching. The fabricated rectifier achieves a measured efficiency exceeding 40% across a wide frequency range of 1.1–3.9 GHz, corresponding to a 112% relative bandwidth at a low input power level of 0 dBm. In addition to its wideband and efficient performance, the rectifier features a highly compact form factor of only 18 × 24.8 mm 2 .