Compact CPW-fed circularly polarized antenna for wlan application

Abstract

A novel compact CPW (coplanar waveguide-fed) CPSS (Circularly polarized square slot) antenna is presented. The proposed single-layer antenna is composed of a rectangular ground plane embedded with two equal-size patches along two orthogonal directions. Equal amplitudes with 90◦ phase difference values of two patches are capable of generating a resonant mode for exciting two orthogonal E vectors. Axial ratio (AR) bandwidth is significantly enhanced due to slot corner modification. The designed CPSS antenna is compact in nature with volume of 0.37λ0 × 0.34λ0 × 0.012λ0 mm3 (λ0 =free space wavelength at centre frequency of the CP bandwidth). It has impedance bandwidth between 4.65– 6.72 GHz (36.41%) and 3-dB axial-ratio bandwidth of 520 MHz (4.85–5.37 GHz), which covers 4.9 GHz (802.11j) WLAN for public safety ranging from 4.94 GHz to 4.99 GHz and WLAN (U-NII-1 and U-NII-2A) ranging from 5.150–5.350 GHz for indoor use. The gain variation for the frequencies within the CP bandwidth is also observed to be less than 0.4 dBic. The design is successfully implemented, and measured results are compared with the simulated ones, which are found good agreement.