Multidirectional Microwave Power Transfer With Dual-Side PAPR Control for Improved Power Capability

The demand for multireceiver microwave power transfer (MPT) is increasing, driving research on enhancing both transmission efficiency and received power. To achieve this, both the power conversion efficiency (PCE) at multiple energy receivers (ERs) and the output power capability of the energy transmitter (ET) must be considered. This article proposes a multitone signal design for MPT using multidirectional multisine waveforms in a planar array antenna, which maintains high peak-to-average power ratio (PAPR) at the ERs while reducing PAPR at the ET via envelope shaping and phase offset optimization. Simulation and experimental results using a 16-channel digital beamforming system confirm that the proposed method improves both ER-side PCE and ET-side power capability. Under a three-directional MPT scenario, the proposed method reduced the average PAPR at central ET elements by 0.55 dB with two-tone signals compared to conventional continuous wave (CW) transmission, resulting in ER-side PCE improvements of 4.0 and 5.6 percentage points under 430 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$680~\Omega $</tex-math> </inline-formula> loads, respectively. With four-tone signals, it maintained a similar PAPR to CW while achieving PCE improvements of 3.4 and 8.4 points under the same load conditions. It also showed reduced nonlinear distortion under high transmit power, enhancing system performance on both the transmit and receive sides.