Wideband Cavity-Backed Crossed Dipoles for Circular Polarization

A novel circularly polarized cavity-backed antenna (CBA) excited by crossed bowtie dipoles is presented in this paper. It is fed by a transition from a microstrip line to double-slot lines. The crossed dipoles consist of a top-loaded triangular and a filleted rhombic to achieve the required input impedance relations for circularly polarized radiation. After optimization, a simulated 3-dB axial-ratio bandwidth of 50% and a broadside gain in a range of 7 to 9 dBi are achieved while the standing wave ratio is kept below 2.