Broadband low-scattering and high-efficiency transmission radome by combining phase gradient metasurface and FSS

In this paper, a novel method to achieve high-efficiency transmission radome with broadband low radar cross section (RCS) is proposed by combining phase gradient metasurfaces (PGMs) and frequency selective surface (FSS). The PGMs-FSS is an ultra-thin single-layered structure composed of a modified Jerusalem resonator backed with an FSS. The FSS works as a high-pass filter for transmitting the in -band signals and reflecting the out-of-band signals, and the PGMs works for reducing the RCS. The insertion loss is less than -1 dB within the passband of 15.95 GHz-17.7 GHz. Moreover, the particle swarm optimization (PSO) algorithm is used to extend the RCS reduction bandwidth as well as in -band high transmission. A prototype with a thickness of 0.08 lambda l (lambda l is the wavelength of the low frequency) is designed, fabricated, and measured. The results demonstrate that an over 10 dB RCS reduction is obtained from 7.95 GHz to 18.12 GHz, i.e., the relative bandwidth reaches 78.02%. The proposed method of combining PGM-FSS can be used in designing radomes of stealth platforms for the requirements of broadband RCS reduction as well as high-efficiency signal transmission.