Leaky-Wave Analysis of TM-, TE-, and Hybrid-Polarized Aperture-Fed Bessel-Beam Launchers for Wireless-Power-Transfer Links

Bessel beams (BBs) can be generated at microwave frequencies by means of compact, planar devices based on Fabry-Perot cavity leaky-wave resonators. Most designs are based on the excitation of a single transverse magnetic/transverse electric (TM/TE) leaky mode by means of a vertical electric/magnetic dipole source. In this work, we analyze the important case of a horizontal magnetic dipole, which excites both TM and TE modes, developing an original theoretical framework suitable for resonant radiators. Analytical expressions are provided for the dominant leaky-wave aperture field. The near-field distribution is then evaluated through an accurate numerical integration of the radiating currents and validated through full-wave simulations for the relevant case of a BB launcher when excited by a waveguide-fed slot. Different designs are presented and analyzed in order to obtain TM, TE, and hybrid polarizations, finding in all cases an excellent agreement between simulations and theoretical results. Finally, we evaluate and compare the wireless-power-transfer efficiency of two coupled TM-, TE-, or hybrid-polarized BB launchers when a wireless link is established in the radiative near-field region. Interestingly, full-wave results demonstrate the superior performance of resonant BB launchers in TM or TE polarization with respect to the nonresonant hybrid case.