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

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 ypolarized waves. After integration with the proposed holographic metasurface, it exhibits absorption-reflection-absorption and wideband absorption responses for the yand 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.