Nonuniform Fabry–Perot Leaky-Wave Antenna With Flat-Topped Radiation Patterns for Microwave Wireless Power Transmission

The uniform Fabry-Perot leaky-wave antennas (LWAs) achieve pattern shaping due to a controlled aperture phase field, which is implemented by using a partially reflective surface (PRS) with a variable propagation constant on a ground plane. The uniform PRS can convert the radiation pattern from a pencil beam to a flat-topped beam when tuning the phase constant. Meanwhile, the beamwidth of the flat-topped uniform LWA becomes inevitably wide. The nonuniform LWA, which can provide nonlinearly variant phase aperture field, is thus proposed to narrow the beamwidth of the flat-topped pattern. The concentrated flat-topped radiation pattern is much preferred in microwave wireless power transmission. The synthesis of a flat-topped nonuniform LWA with a concentrated pattern is proposed. A nonuniform LWA with a periodic mesh grid has been fabricated and measured for verification. Compared with the uniform LWA, the measured results indicate 1.7 dB gain increment and 10° beamwith shrinkage, which proves the effectiveness of the proposed method.