Design and analysis of a multi-layer circuit absorber with ultra-wideband and polarization insensitivity

This study presents an ultra-wideband, polarization-insensitive circuit analog absorber composed of multilayer resistive frequency selective surface structures. The proposed absorber architecture is characterized by a periodic configuration of square shaped loops incorporating lumped resistors, which are placed on dielectric layers that are interspersed with an air spacer. The simulated results demonstrate a reflection coefficient of less than - 10 dB within the frequency range of 5.2-20.09 GHz, exhibiting a fractional bandwidth of 117.75% under normal incidence. This performance encompasses the C, X, Ku, and K bands. The absorber design theory has been inspected then simulated in full wave analysis software CST microwave studio. The influence of parametric variations, including resistor values and the height of the air spacer, has been investigated to validate the sensitivity of the design parameters on the absorption bandwidth.