Metasurface Instrumented High Gain and Low RCS X-Band Circularly Polarized MIMO Antenna for IoT Over Satellite Application

In this article, a ultra-wideband (UWB) metasurface absorber is designed for a frequency range of 6.75–14.5 GHz. The absorber consists of a simple unit cell size of
$0.265\,\,\lambda _{o} \times 0.265\,\,\lambda _{o} \times 0.103\,\,\lambda _{o}$
on a single-layer FR-4 substrate with a thickness of 3.1 mm. It has greater than 90.0% absorbance. Next, an
$X$
-band circularly polarized MIMO antenna is developed on an FR-4 substrate with a thickness of 1 mm. The antenna has dimensions of
$0.966\,\,\lambda _{o} \times 0.766\,\,\lambda _{o} \times 0.053\,\,\lambda _{o}$
. The MIMO antenna’s S-parameters, radiating efficiency, gain, and diversity parameters are further indicators of its usefulness. The designed metasurface is also employed as a tool to enhance the peak gain of the proposed MIMO antenna up to 8.8 dBi and reduce radar cross Section (RCS) by 18 dBm
²
, by placing the metasurface array superstrate and down correspondingly. The simulated and measured results for the metasurface and antenna, both individually and collectively, are more harmonious, demonstrating the applicability of the suggested designs for the Internet-of-Things (IoT) over satellite, military applications, and identifying blood clots in CT-scan applications.