Circular polarization realization in array antennas by a modified sequential phase feeding mechanism of linearly polarized elements

Novel designs of a circularly polarized 2 x 2 and 4 x 4 slot array antennas (CPSAAs) are proposed. Sequential phase feed network composed of a section of 270 degrees and four strips is utilized to feed the array structures. Array elements are simple linearly polarized wide slot antennas (WSAs) composed of simple radiating patches with truncation on four corners and slotted ground plane on substrate backside. Each WSA operates over the UWB frequency band of 3.1-10.6 GHz. When the WSAs are arranged in the form of 2 x 2 and 4 x 4 CPSAAs, frequency bands of 3-13.1 and 1.4-12.3 GHz are covered, respectively. More importantly, CP is generated at 4.5-8 and 4.6-8.8 GHz for 2 x 2 and 4 x 4 CPSAAs, respectively. This is while; the WSAs are linearly polarized elements. Higher gain values and wider bandwidths are obtained with respect to single WSA. Design process and performance analysis of the single and array antennas are discussed through the paper.