Ultralow-Profile Folded Transmitarray with Low RCS by Combining Two Asymmetric Reflections and Integrated Absorption-Scattering

In this letter, we propose a strategy of engineering an ultralow-profile folded transmitarray (FTA) with low radar cross section (RCS). The architecture integrates a frequency selective rasorber (FSR), a transmissive-reflective metasurface (TRM), a focusing polarization-conversion metasurface (FPCM), and a feed horn. Two operation modes are engineered to simultaneously achieve high-gain radiation and low observability. For radiation, spherical waves from the feed are transformed by the TRM and FPCM into a high-gain beam. Therein, two asymmetric reflections are employed achieving an ultralow profile of 1/7 the focal length. For invisibility, out-of-band and in-band RCS reduction are achieved by FSR absorption and TRM scattering, respectively. For verification, a proof-of-concept prototype is numerically and experimentally characterized, indicating a measured peak gain of 24.6 dBi with a corresponding aperture efficiency of 26% at 14.1 GHz. In addition, a relative bandwidth of 10 dB RCS reduction is reached as 95.5% and 87.1% for co- and cross-polarized incident waves, respectively. Such a highly integrated stealth meta-FTA exhibits strong potential for stealth communication systems.