RF Rectifiers With Wide Incident Angle of Incoming Waves Based on Rat-Race Couplers

This article presents a radio frequency (RF) rectifier with a wide incident angle of incoming waves, based on a rat-race coupler (RRC). Two identical sub-rectifiers replace the two load circuits of the conventional RRC. When compared with the previous Wilkinson power combiner (WPC)-based rectifier, the proposed topology advances with a smaller variation in power conversion efficiency (PCE) over the incident angle. In addition, it simplifies the matching network (MN) design and enables a lower input return loss due to the fully symmetric circuitry between 0° and 180°. Furthermore, it allows a higher design flexibility on the rectifier topology. For validation, we designed and fabricated two wide-angle rectifiers, one working at single band (2.45 GHz) and the other at dual band (0.9 and 2.4 GHz). The single-band rectifier achieved a 67.3% peak PCE and 7.9% efficiency variation within the 0°–360° incident angle range. For the dual-band rectifier, the peak PCE is 78.4% and 70.2%, while the variation is 4% and 8.8%, for 0.9 and 2.4 GHz, respectively. The PCE variation is the smallest among previous works.