Design of radar absorbers using frequency selective surfaces for stealth applications

Abstract

Electromagnetic absorbers are specially designed structures to absorb the incident electromagnetic wave on the surface and have the ability to reduce reflections. They are used in electromagnetic shielding, reduction of electromagnetic radiation, etc. The radar absorbers are designed to prevent military vehicles, fighter jets, from being detected by enemy radars. Absorbers work on the principle of impedance matching, and when the impedance of the absorber matches the free space impedance, the incident electromagnetic energy is converted into thermal energy and dissipated as heat. newlineIn general, absorbers are built by employing a resistive sheet at a distance of a quarter wavelength from a back plane. Usually, metallic back planes are employed in absorbers to make the surface transmission of the absorber zero. The absorbers are categorized into Salisbury screens, Jaumann absorbers, and frequency selective surface (FSS)-based absorbers. The FSS-based absorbers make use of the capacitive and inductive nature of the FSS, resulting in thin absorbers. FSS absorbers are classified as narrow band absorbers and broad band absorbers. newline