X-band circular polarization array antenna with parallel arrangement of three-element plane antennas

— This paper presents novel configuration of wideband microwave circular polarization antenna. This array antenna is composed of four units of three elements plane antennas. This unit antenna is composed of three circular elements of feed and reactance elements on a ground plane. The unit antenna is composed of a feed and a reactance elements on a ground element. The feed element is made of a disc truncated at both sides to separate generation of higher and lower frequencies ( f H and f L ), Four units of the above antenna are applied to the parallel array antennas. It was found that the axial ratio was about 3 dB or less at the frequencies 9.5, 10.0, and 10.5 GHz. But minimum axis ratio of around 0 dB was not achieved by parallel arrangement of four antennas.