Extending axial ratio bandwidth of antenna array by parasitic patches

In the paper, axial ratio bandwidth of a circularly polarized antenna array is increased by parasitic patches placed above the original structure. A 2×2 circularly polarized patch antenna array was used as a reference. Performed simulations at center frequencies 17 GHz and 60 GHz show correspondence: the axial ratio bandwidth was increased from 6.7% to 16.7% at 17 GHz, and from 7.6% to 19.1% at 60 GHz.