Wideband Low RCS Circularly Polarized Antenna Array Based on Hybrid Absorptive Frequency Selective Structure

In this paper, we propose a wideband low radar cross section (RCS) circularly polarized antenna array based on a hybrid absorptive frequency selective structure. To achieve wideband RCS reduction, a two-dimensional absorber and a three-dimensional absorptive frequency selective transmission (AFST) structure are successively integrated above the antenna. Furthermore, the transmission window of the AFST aligns with the operating band of the antenna to ensure its radiation performance. Specifically, the absorber consists of two perpendicular bent metal strips with central loading resistors, AFST is realized by adding a split-ring resonator in the center of the metal strip with resistors, and the circularly polarized antenna includes cutting radiation and parasitic patches. A prototype of 8× 8 antenna array is designed, fabricated, and measured. Experimental results show that the antenna achieves a wide operating band of 13.1∼ 14.8 GHz within a broad RCS reduction band of 2∼ 20 GHz. The in-band realized gain is large than 19.5dBi, and the maximum gain is 21.4 dBi.