Circularly Polarized Cavity-Backed Antenna with Variable Magneto-Electric Crossed-Dipole Structure

The authors propose a mode conversion technique in a cavity-backed circularly polarized magneto-electric (ME) antenna in order to achieve a wide axial ratio (AR) beamwidth covering a wide frequency range. The proposed technique allows both the ME antenna element and the cavity structural parameters to be independent of each other, which would otherwise always be associated with each other. The proposed antenna demonstrated impedance bandwidth $(\vert S_{11}\vert \leq-10\text{dB})$ of 38.73% (1.52-2.25 GHz), 3-dB axial ratio bandwidth of 33.05% (1.49-2.08 GHz), and 3-dB AR beamwidth exceeding 214° in a single plane ( $xz$ or $yz\text{-plane}$ ) across the operating band.