Low-radar cross section wideband circularly polarized patch antennas by controlling scattering and surface wave propagation with a coding metasurface

A new method using a 1-bit coding metasurface to reach a low radar cross section (RCS) for a wideband circularly polarized (CP) patch antenna is proposed. The essence of the technique is to simultaneously control phase cancelation and surface wave propagation with the coding metasurface. The metasurface cell is a simple rectangular patch with a 180° phase difference between x- and y-directions. In terms of radiation performance, owing to the propagated surface waves, two TM10 and TM30 modes are excited and the wideband CP radiation is achieved. In terms of scattering performance, owing to the phase cancelation of the sequential-rotated pattern, the backward RCS of the proposed antenna is reduced for both in-band and out-band frequencies compared to that of the conventional antenna. A prototype operating at C-band is fabricated and measured. Experimental and simulation results are in good agreement. The CP bandwidth (both |S11| < −10 dB and AR < 3 dB) is extended to 10.0%, and the peak gain is enhanced to 8.90 dBi.