A transmissive dual-beam low-rcs metasurface antenna based on a highly selective frequency selective rasorber

This paper proposes a highly selective absorption-transmission-absorption (A-T-A) type frequency selective rasorber (FSR). Through collaborative optimization of the interdigital resonator and a three-layer cascaded bandpass frequency selective surface (FSS), it achieves 0.08 dB minimum insertion loss, Q-factor of 10.5, and two wide absorption bands (5.1–12.4 GHz and 14.8–19.2 GHz). Besides, a transmissive phase modulation unit is designed to build a 15 × 15 2-bit coded array, realizing dual-beam radiation with 24.6 dBi gain at 13–14 GHz. By placing the FSR above the dual-beam array, both wideband radar cross section (RCS) reduction and dual-beam high-gain radiation are achieved. In radiation mode at 13.5 GHz, the antenna generates symmetrically tilted dual beams at ±39° with gains of 23.2 dBi and 21.4 dBi, respectively. In scattering mode, the 10-dB RCS reduction performance depends on incident wave’s polarization. For x-polarized incidence, two bands of 5.1–12.8 GHz and 14.2–20.1 GHz are covered, and For y-polarized incidence, a continuous wide band of 5.2–20.1 GHz is covered.