A CPW-FED WIDEBAND CIRCULARLY POLARIZED SLOT ANTENNA WITH FSS FOR ENHANCED GAIN

A CPW fed slot antenna is proposed. The slot is rectangular in shape and is excited by a two step feed terminated on a circular disc which protrudes into the slot center. Perturbations in the form of metallic L-shape strips are attached at two opposite corners of the slot while the other two slot corners are blended with circular arcs. Further, slant narrow rectangular slits are cut on the circular disc. The frequency selected surface (FSS) designed to improve the gain and the Circular Polarization (CP) of the antenna is an array of rectangular metallic patches printed on one side of a substrate. The antenna-FSS combination achieves an impedance bandwidth of 2.3-12.0 GHz (136%, measured). The 3-dB axial ratio bandwidth (ARBW) achieved by the combination is from 4.3-6.9 GHz (46.4%, measured). The measured peak gain is 7-8 dBi over much of the band which is an enhancement of about 4 dBi when compared to the antenna without the FSS. The antenna along with the FSS can be useful for CP applications such as in ground penetrating radar and vehicular radar where high gain is additionally required. (C) 2015 Wiley Periodicals, Inc.