Enhanced near-field focusing with amplitude–phase arrays for microwave power transmission: Analysis, design, and experiment

This paper proposes an enhanced near-field focusing method for microwave power transmission (MPT) using amplitude–phase array design. With the growing demand for power autonomy in IoT and mobile devices, MPT has become a promising solution. To improve system-level efficiency, subarray-based antenna architectures are employed. Conventional phase-only MPT systems suffer from degraded efficiency in partially covered regions outside the full 3 dB beamwidths of transmit elements. This work defines and analyzes this quasi-blind range and proposes a tilted beam strategy combining amplitude and phase control to address it. Design guidelines are derived analytically and validated experimentally using a 64 × 64 transmitter array with 8 × 8 slot subarrays and a 32 × 32 receiver array with 2 × 2 stacked patch subarrays. The proposed method demonstrates a 42.40% improvement in air efficiency, with strong agreement between simulation and measurement.