A Broadband Rectifier With Wide Incident Angle of Incoming Waves Based on Quadrature Coupler for RF Energy Harvesting

In this letter, a broadband rectifier with a wide-incident-angle (WIA) property is proposed. The circuit is composed of a broadband quadrature coupler (BQC) and two broadband subrectifiers (RectA and RectB). Here, RectA and RectB are connected to the two output ports of the BQC and combined by a direct current (dc) power combiner. Then, the obtained dc power is transmitted to the load resistor. Besides, two RF sources (RF1 and RF2) with identical input power and a phase difference (<inline-formula> <tex-math notation="LaTeX">$\Delta \varphi$ </tex-math></inline-formula>) are connected to the input and isolated ports of the BQC. A detailed theoretical analysis is carried out. To validate the proposed scheme, we design a broadband (1.6–2.8 GHz) WIA rectifier. Measurement results show that the power conversion efficiency (PCE) exceeded 60% in the frequency range from 1.6 to 2.8 GHz at 13.1 dBm of the input power. Additionally, at 2.45 GHz, the PCE varies in the range of 60.8% and 72.6% within the entire <inline-formula> <tex-math notation="LaTeX">$\Delta \varphi $ </tex-math></inline-formula> range (0°–360°). Thus, the obtained PCE variation (<inline-formula> <tex-math notation="LaTeX">$\Delta \eta$ </tex-math></inline-formula>) is 11.8%. Considering its excellent broadband and WIA features, it is very suitable for high-efficiency radio-frequency (RF) energy harvesting (RFEH) systems.