A Microwave Power Transmission System Using Sequential Phase Ring Antenna and Inverted Class F Rectenna

Abstract

A high-efficiency microwave power transmission (MPT) system based on an inverted class F (F-1) rectifier for microwave wireless charging applications is presented in this paper. A left-hand circular polarization (LHCP) transmitting antenna (Tx) is designed based on a modified sequential phase rotation (SPR) divider integrated with a 2 x 2 array. The proposed Tx exhibits compact size with LHCP maximum gain of 11.85 dBi at 5.8 GHz. Furthermore, the receiver is composed of an LHCP receiving antenna (Rx) and a microwave F rectifier. To realize the power radiated region of the Tx, an Rx with a wide beamwidth for minimizing distance loss is proposed, which has a 3-dB axial ratio (AR) beamwidth of 165.55 degrees and 175.17 degrees in the x-z and y-z planes, respectively. In addition, to improve the RF to DC conversion efficiency (eta), the class F harmonic processing network is utilized at the load of the rectifier that can process the voltage and current waveforms without using a DC pass filter. The proposed F-1 rectifier circuit occupies a compact area of 15.3 x 12.7 mm(2), and it exhibits an average eta of 50% for the input power range from 4 to 20 dBm with a peak efficiency of 77.9% at 18 dBm. Overall, the experimental results show that our proposed system achieves a maximum power transmission efficiency (PTE) of 8.8% for wirelessly charging low-power multiple devices at a distance of 60-200 mm.