Low-RCS Holographic Antenna With Enhanced Gain Based on Frequency-Selective Absorber

Abstract

This article presents a low radar cross-section (RCS) holographic antenna with enhanced gain based on a frequency-selective absorber (FSA). The proposed antenna consists of a feed monopole antenna, a holographic metasurface using slotted patches, and a two-layered resistive metasurface. Within its operating band, the holographic metasurface manipulates the surface wave into a $y$ -polarized broadside plane wave and vice versa, which simultaneously realizes high gain and in-band low RCS for $y$ -polarized incidence. In addition, slotted patches are utilized as unit cells of the holographic metasurface to further enhance the antenna gain. The resistive metasurface used in the proposed antenna has a transmission window for the $y$ -polarized waves. After integration with the proposed holographic metasurface, it exhibits absorption–reflection–absorption and wideband absorption responses for the $y$ - and $x$ -polarized waves, respectively. Thus, not only is good radiation performance maintained but also the in-band RCS for $x$ -polarized incidence and out-of-band RCS for both polarizations are significantly reduced. Compared to a conventional holographic antenna, the gain of the proposed antenna was enhanced by 1.4 dB at 10 GHz. Both the monostatic and bistatic RCS were significantly reduced in the frequency range 4–17 GHz. The measured results of a fabricated prototype of the proposed antenna were in good agreement with simulations.