Ultrabroadband Monostatic/Bistatic RCS Reduction via High-Entropy Phase-Encoded Polarization Conversion Metasurfaces

Abstract

A randomized phase-encoded polarization conversion metasurface (RPPCM) is designed in this letter to reduce both monostatic and bistatic radar cross section (RCS) levels of a microstrip antenna working at 2.45 GHz, simultaneously. A fast entropy-based method is elaborately utilized to extract the optimum diffusion layout with low time consumption. The designed RPPCM exposes low monostatic and bistatic RCS signatures (RCSR $>$ 10 dB) in a wide frequency range from 8.2 to 25.6 GHz (BW = 102%). The performance of the proposed RPPCM has been significantly improved with respect to the similar designs, as compared through this letter. To validate the performance of our design, a low-scattering microstrip antenna is also designed, fabricated, and measured, in which by loading the RPPCM around the patch of antenna, in addition to rotating the incident wave polarization, it is capable of distributing the incident power into many undetectable scattered beams with minor influences on radiation specifications. The experimental results of the fabricated prototype corroborate well the corresponding numerical simulations, where RCSR $>$ 5 dB has been obtained in a broadband region from 6.7 to 24 GHz (BW = 113%).