In this article, a UWB metasurface absorber is designed for a frequency range of 6.75GHz-14.5GHz. The absorber consists of a simple unit cell size of 0.265λ ₀ ×0.265λ ₀ ×0.103λ ₀ on a single-layer FR-4 substrate with a thickness of 3.1mm. 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 1.0mm. The antenna has dimensions of 0.966λ ₀ ×0.766λ ₀ ×0.053λ ₀ . 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 8.8dBi and reduce radar cross-section by 18dBm 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 IoT over satellite, military applications, and identifying blood clots in CT-scan applications.

In this article, a meander line-shaped pentaband (2.18–2.24, 2.38–2.46, 2.65–2.70, 3.10–3.32, 3.38–3.46 GHz) four-element multiple-input–multiple-output antenna is presented. The proposed antenna is also circularly polarized in two bands (at 2.2 and 2.4 GHz) with dual-polarization like right-handed at port 1 or 3 and left-handed at port 2 or 4, which is widely used for mobile satellite services (MSS) and Internet of Things applications. This antenna is designed and fabricated with compact size 50 × 70 × 1.6 mm³ on the FR-4 substrate with good diversity performance in pentaband. Simulated results of antenna-like return loss, isolation, and parameters-related diversity have also been tested experimentally in a controlled environment, which is within the permissible limit. The designed antenna will be appropriate for MSS, industrial scientific and medical (ISM), broadband radio services and educational broadband services, WiMAX radio location services, and amateur radio services. Meanwhile, specific absorption rate of the designed antenna has been examined in an empirical environment for the Fresnel radiating near-field applications.