A Rectifier Circuit Insensitive to the Angle of Incidence of Incoming Waves Based on a Wilkinson Power Combiner

Abstract

In this paper, a novel high-efficiency, low-cost, and low-complexity RF-to-dc converter was designed for RF energy harvesting in the 2.4-GHz band. The proposed design has two RF inputs and maintains high efficiency over a wide range of incoming incident wave angles. The circuit is based on a Wilkinson power combiner and has two single-diode rectifiers. One rectifier is connected at the combiner's output and collects the energy coming from the two inputs. The second rectifier replaces the isolation resistor of the combiner in order to collect the power that would, otherwise, be dissipated in it. The second rectifier is used for recycling the wasted power when the input signals do not have the same phase. The novel RF-to-dc converter was fabricated using the commercially available components and a low-cost FR-4 substrate. A prototype was designed, and its efficiency was optimized for low-power input levels. The measured system efficiency was 16.2% for in-phase input signals with an available input power of -17 dBm. When the relative phase of input signals varied from 0° to 360°, a variation in efficiency between 15.3% and 22% was observed. For an input power of 3 dBm, the efficiency varies from 26% to 39% between 0° and 360° phase difference.