Compact fan shaped circularly polarized microstrip patch antenna

Abstract

A novel compact single-feed fan shaped microstrip patch antenna for circular polarization is proposed and investigated. The compact size is achieved by insetting four equally spaced sectoral slits to the periphery of the circular patch which lowers down the resonant frequency of the circular patch. By carefully selecting sectoral slit pairs of different length along the axis of the patch, the lowered dominant mode resonant frequency splits into two close-degenerate distinct resonant frequencies resulting in circular polarization. The performance of the antenna for different sectoral slit lengths is also studied. The proposed antenna with 48.53% miniaturization as compared to the conventional standard-size circularly polarized design is fabricated and measured. The antenna exhibits an overall size of 0.3λ0×0.3λ0×0.009λ0 at 1.8 GHz with measured 2.05% 10-dB impedance bandwidth and 0.44% 3-dB axial bandwidth. The antenna is simple, easy to fabricate, and suitable for GSM applications. Its measured and simulated results are in well agreement.