Wideband circularly polarized slot antenna

A microstrip-fed symmetric-slot antenna is proposed for wideband circularly polarized radiation. The antenna consists of a microstrip feed line and a wide symmetrical slot along the diagonal axis. The slot and feeding structure are fabricated on the opposite plane of a low cost FR4 substrate. The wideband is achieved by changing the symmetric-shaped slot lengths and a strip-line length. The measured 3-dB axial ratio and 10-dB return-loss bandwidths of the antenna are around 50% and more than 100% respectively. The boresight gain and backside gain is more than 3.0 dBic over the 3-dB axial ratio bandwidth.