Broadband circularly polarized microstrip-fed circular slot antenna array

This letter presents a novel broadband circularly polarized (CP) microstrip-fed slot antenna array. The element of the array is comprised of a microstrip-fed circular disk and a circular slot. A rectangular slot is notched on the disk to excite circularly polarized radiation. The parameters which affect the performance of the antenna are investigated. The proposed antennas are sequentially rotated to form a 2×2 antenna array and series feed network is applied to feed the elements. The simulated and measured results are with good agreement. The experimental results indicate that the antenna array has a 3 dB axial ratio (AR) bandwidth of 64.5% and the −10 dB return loss bandwidth is 78.4%. The 3dB gain bandwidth is about 38.1% with the peak gain 10.1dBi.