Broadband CPW-fed circularly polarized square slot antenna with combining C-shaped strip and asymmetry ground plane

A new broadband circularly polarized (CP) square slot antenna with coplanar waveguide (CPW) fed is designed in this paper. An asymmetry ground plane makes the adjacent resonant mode to merge into a wide operation bandwidth, and the C-shaped structure can offer the current path, two orthogonal electric fields with a 90° phase difference for exciting a circular polarization radiation wave. The measured impedance bandwidth (VSWR ≤ 2) is 0.92 GHz (46% relative to the center frequency at 2 GHz). The 3-dB axial ratio bandwidth (ARBW) is 0.65 GHz (32.5% relative to the center frequency at 2 GHz), and antenna peak gain is 3.31 dBi with gain variations of less than 1 dB.