Compact annular-ring embedded circular patch antenna with cross-slot ground plane for circular polarisation

A compact circular patch antenna embedded in a narrow annular-ring which uses an unequal cross-slotted ground plane is presented. This new compact structure provides circular polarisation and is easily matched to 50 Ω at the low frequency of operation. The size of the proposed antenna is reduced by over 55% compared to the conventional annular-ring CP patch antenna with a strip. The bandwidth and centre-frequency show weak dependence on the position of the feedpoint in the patch and demonstrate wider manufacturing tolerances. Good circularly polarised properties and wide bandwidth are obtained for the proposed compact antenna.