Gain enhancement of wideband circularly polarized UWB antenna using FSS

This paper presents a new ultra-wideband (UWB) antenna system with circular polarization (CP). The antenna is a coplanar waveguide (CPW) feed structure with a modified inverted L-shaped radiating patch. A single-layer non-uniform frequency selective surface (FSS) composed of rectangular conductive patches is designed and used with the CP antenna to improve the CP characteristics and the gain of the antenna. According to the measured results, the 10 dB return-loss bandwidth of the antenna with the FSS extends from 3.7 to 11.1 GHz. The 3-dB measured axial ratio (AR) bandwidth is 58.15%, covering 5 to 9.1 GHz, and the measured peak gain is 4–9.4 dBi, showing an increase of about 3 dBi compared to theantenna without the FSS.