Dual-CP Antenna With Wide-HPBW and Wide-ARBW Performance for Wide-Angle Scanning Phased Array

In this communication, a novel dual-circularly polarized (CP) antenna with both wide half-power beamwidth (HPBW) and wide axial-ratio beamwidth (ARBW) is proposed. Based on the septum circular polarizer, the principle about HPBW improvement of its $\vert E_{\mathrm {\theta }}\vert $ and $\vert E_{\mathrm {\varphi }}\vert $ components is extensively studied. It proves that the metal rings around the top surface could be used to enhance the low elevation gain and extend its HPBW of $\vert E_{\mathrm {\theta }}\vert $ components. Subsequently, a set of slots is introduced on the waveguide to expand the HPBW of its $\vert E\varphi \vert $ component. With these arrangements, both ARBW and HPBW parameters of the antenna are simultaneously widened while keeping wide impedance bandwidth as desired. In addition, the antenna element is constructed as the $1\times8$ phased array for wide-angle scanning in such a way that the array antenna can satisfactorily achieve a wide CP scanning range and stable radiation pattern. Finally, the proposed antenna is designed, fabricated, and measured. The results evidently reveal that the proposed element can simultaneously achieve 3-dB HPBW and 3-dB ARBW in the range of 130° in 3.8–4.2 GHz, and its inspired array can effectively achieve beam scanning from -60° to 60° in 3.9–4.2 GHz.