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 ( $\text{F}^{-1 }$ ) 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 $2\times 2$ 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 $\text{F}^{-1}$ 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° and 175.17° in the $x - z$ and $y - z$ planes, respectively. In addition, to improve the RF to DC conversion efficiency ( $\eta $ ), the class $\text{F}^{-1}$ 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 $\text{F}^{-1}$ rectifier circuit occupies a compact area of $15.3\times12.7$ mm2, 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.

Keywords

• Circularly polarized antenna
• harmonic processing
• microwave rectifier
• wireless power transmission (WPT)
• wireless charger