Design of Low-RCS Circularly Polarized Phased Array Based on Absorber With Common Aperture

In this communication, a novel circularly polarized (CP) phased array design with low radar cross section (RCS) is proposed. On the one hand, a wideband absorber consisting of multiple-layer multiple-order hybrid metasurface is designed based on dual-polarization tightly coupled bow tie dipole patch. On the other hand, an X-band CP microstrip (CPMS) antenna is designed to share the common aperture with the absorber metasurface and function as part of the absorber. Therefore, the proposed antenna element, composed of absorber and microstrip antenna, features CP radiation and in-band absorption characteristics. This design is of great help to achieve wide-angle dual-polarization 2-D RCS reduction within the inclusion band while maintaining wide-angle CP radiation. Finally, the antenna element is expanded to 4 x 4 phased array. Experimental evaluations confirm the antenna’s performance. The measured impedance and axial ratio (AR) overlap bandwidth of the proposed array is 11.2% (8–8.95 GHz). Additionally, the scanning range reaches ±50° in both the xoz and yoz planes. Reliable 2-D bistatic RCS reduction is realized within the incidence angle range of ±55° for TE waves and ±70° for TM waves. Notably, wideband monostatic RCS reduction is realized in the range of 1.70–9.15 GHz (137%) for x-polarized incident wave and 1.70–9.05 GHz (137%) for y-polarized incident wave.