Low-RCS Transmitarray Based on 2.5-D Cross-Polarization Converter

This article presents a low radar cross Section (RCS) transmitarray with absorption–transmission–absorption frequency response. In contrast to conventional transmitarrays based on multilayer metallic patterns, a 2.5-D cross polarization converter is employed to provide a large phase shifting range of high transmission efficiency. A benchmark transmitarray composed of the polarizer element with an aperture thickness of 2.3 mm ( $0.08\lambda$ ) is designed to achieve a focused radiation beam. As a result, its peak gain is 22.1 dB and maximum aperture efficiency is 57.6%. Next, a low-RCS transmitarray is designed by introducing a lossy layer to absorb the out-of-band incident waves. Compared with the benchmark antenna, the radiation performance of the low-RCS transmitarray is maintained with a peak gain of 21.7 dB and maximum aperture efficiency of 53.7%. Meanwhile, dual-polarized significant RCS reduction can be obtained at both lower and higher frequencies.