S-Band Full-Metal Circularly Polarized Cavity-Backed Slot Antenna With Wide Bandwidth and Wide Beamwidth

In this communication, an S-band wide-bandwidth and wide-beamwidth full-metal circularly polarized (CP) cavity-backed slot antenna is proposed. A pair of triangular prisms placed at the corners of the cavity is introduced to produce TE101 and TE011 modes with orthogonal electric fields. These two modes are used to achieve the CP radiation and radiate the energy through a single-circular slot. By simultaneously varying the prisms' size and slot radius, the axial ratio (AR) bandwidth (ARBW) improves. The ARBW is further improved by replacing the circular slot with an elliptical slot. As a result, the ARBW increases from 1.0% to 10.3% without complicating the antenna structure and without enlarging the antenna size. Besides, the antenna still operates at two degenerate modes to introduce stable radiation gain and pattern. In addition, the proposed CP slot antenna features a wide ARBW. The final measurement shows that the proposed CP antenna can achieve a 9.5% bandwidth, a stable gain of 7.65 dBic +/- 0.15 dBic, and higher than 140 degrees ARBWs in a wide frequency range. The peak total radiation efficiency and aperture efficiency are about 97% and 91%, respectively.

Automated summary

In this study, an S-band wide-bandwidth and wide-beamwidth full-metal circularly polarized cavity-backed slot antenna is proposed, utilizing triangular prisms to generate orthogonal electric fields for CP radiation and improving ARBW by adjusting prism size and slot radius, and further enhancing ARBW by using an elliptical slot. The proposed CP antenna features a wide ARBW, achieving a 9.5% bandwidth and stable gain.