Broadband CPW-FED Circularly Polarized Antenna with Equiangular Tapered-Shaped Feedline for Ultra-Wideband Applications

A novel coplanar waveguide (CPW)-fed circularly polarized (CP) antenna is proposed. The antenna is composed of a square ground plane with a circular slot and an equiangular tapered-shaped feedline. With the use of a special shaped feedline, the axial ratio (AR) bandwidth of the proposed antenna is about 61.9% (2.9-5.5 GHz), which is larger than most of similar antennas proposed before. In addition, the impedance bandwidth, determined by 10-dB return loss, is between 2.9-20 GHz, which makes the antenna be used for ultra-wideband (UWB) applications.