Capacitive-Loaded Ultra-Thin Metamaterial Absorber for X-band with Polarization Insensitivity

The X-band’s versatility stems from its optimal combination of relatively high frequency and effective penetration through the atmosphere, making it a versatile choice for various applications across different domains. This article proposes a low-cost, multiband, and polarization-insensitive single-layered capacitively loaded microwave metamaterial absorber in X-band for surveillance radar application. The super unit cell of the designed absorber is constructed by arranging an array of two subunit cells, where one is a 90° rotated version of the other, exhibiting diagonal symmetry. Further, the electrical size and thickness of the absorber are reduced using capacitive loading by inserting slots in the design. The proposed absorber offers triple-band functionality at frequencies of 8.9,10.4, and 11.2 GHz, boasting absorptivity rates of $99 \%, 91 \%$, and $99.8 \%$ within the X-band spectrum.