Wideband circularly polarized array antenna based on weakly coupled sequential phase feed network

This letter introduces a wideband circularly polarized (CP) array antenna for wireless communication application. The array consists of 2 x 2 sequentially rotated symmetric antenna elements and a wideband weakly coupled feed network providing stable 90 degrees phase difference. By using the proposed feed network and introducing the slot coupling feed, the CP array antenna can achieve a wideband CP performance with a low profile of 0.03 lambda(0) (at 5.0 GHz). The proposed antenna exhibits the impedance bandwidth (IMBW) of 73.9%, axial ratio bandwidth (ARBW) of 53.6%, and 3-dB gain bandwidth (GBW) of 60% with the peak gain of 10.4 dBi and the maximum efficiency of 82%. The measured results are in good agreement with the simulated results, indicating that a promising application in compact wideband C-band wireless systems.