Dual-Band Dual-Polarized Waveguide Slot Antenna for SAR Applications

The design of a shared-aperture waveguide slot antenna operating in dual-band and dual-polarization (DBDP) is proposed in this letter for synthesis aperture radar (SAR) applications. The frequencies of the antenna are in both L- and C-band with frequency ratio of 4:1. The C-band horizontal-polarized subarray antenna is achieved by 16 V-shaped slots opened on a ridged waveguide, while the vertical-polarized subarray is realized by 16 longitudinal slots displaced from the centerline on the other ridged waveguide. The L-band vertical-polarized subarray is comprised by four groups of longitudinal slots cut in the metal-wall interlacing with the C-band dual-polarized antenna array sharing the same aperture. The L-band waveguide is a multiridge cavity under the C-band waveguide. A DBDP antenna module comprising 4 x 16 C-band dual-polarized elements and 1 x 4 L-band elements was manufactured in aluminum alloy. Experimental results show that the proposed antenna can obtain excellent electromagnetic performance and maintain satisfactory thermal and mechanical properties for space-borne SAR applications.