Single-Layer Rectenna Array With Integrated Matching Circuit for Wireless Power Transfer

This article reports an efficient single-layer rectenna array at 5.8 GHz. The patch antenna is directly matched to the Schottky diode impedance by a high impedance transmission line without extra matching circuit. By controlling the width and length as well as position of the transmission line, good conjugate matching can be achieved. Not only the size, but also the insertion loss of the matching circuit can be reduced. And each patch is connected to 4 Schottky diodes to enhance the power handling capability which is attractive in the long-distance high power wireless power transfer (WPT). The dc power combining circuit is connected to the patch at the center of the short edge where dc current can pass and the RF current is zero. The whole rectenna array only has one layer which makes it has lower cost compared with its multi-layer counterparts. To verify, a rectenna element is studied first. The single element rectenna achieves 73.1% RF-to-dc power conversion efficiency (PCE) at 5.8 GHz. When the array is loaded with $2.5~\Omega $ , a $6\times 5$ rectenna array produces 2.34 W of dc output power with an RF-to-dc conversion efficiency of 69.4% and an incident power density of 9.37 mW/cm2. Moreover, a method to calculate the output dc power changing with the incident angle of the incident waves is provided, and the calculated results agree well with the measured results.