A CPW-fed broadband circularly-polarized square slot antenna with E-shaped slits in ground plane

A new broadband circularly polarized (CP) square slot antenna with coplanar waveguide (CPW) fed is proposed. E-shaped slits in opposite corners of ground plane are designed to obtain an excellent CP bandwidth. The bandwidth with an axial ratio (AR) of less than 3 dB can be tuned by varying the length of a tuning-stub which is the middle of the E-shaped slit. Measured results show that the 3 dB AR bandwidth is larger than 32.8% relative to the centre frequency of 2165 MHz and the impedance bandwidth is as large as 54.8% with VSWR ≤2.