A miniaturized circularly polarized microstrip antenna with bandwidth enhancement
A miniaturized single-feed cross-aperture coupled right-handed circularly polarized (RHCP) microstrip antenna with bandwidth enhancement has been presented. The antenna size miniaturization is achieved by the capacitive loading offered by the shorting strips and radiating patch, and the inductive loading induced by the shorting pins. A 0°-90° microstrip hybrid consisting of a cascade of a Wilkinson 3-dB power divider and a 90° phase shifter is designed to feed the antenna to significantly improve its bandwidth. The overall size of the antenna is 50 mm × 50 mm × 6.2 mm (0.33λ0 × 0.33λ0 × 0.04λ0), exhibiting a global bandwidth of 12% ranging from 1.88 to 2.12 GHz, where the return loss is larger than 10 dB, the broadside axial ratio (AR) is smaller than 3 dB, and the gain is above 0 dBic.
