Fast Design of Ultrawideband Absorbers Based on Equivalent Circuit Model

A fast method is presented for designing ultra-wideband absorbers composed of resistive surfaces (RSs), substrates and metallic plates. A general effective permittivity for RSs printed on stratified dielectrics under considering metallic plate is derived to obtain the closed-form relationships between resistance, capacitance and absorber parameters. An equivalent circuit (EC) is developed for absorbers to combine with a genetic algorithm to quickly achieve an optimal value of lumped elements, thereby calculating absorber parameters. Utilizing the proposed approach, an absorber within 0.64-41.7 GHz with a reflection loss lower than −10 dB is obtained efficiently. The close match between the EC model and full-wave simulation results shows the accuracy of the proposed approach. To further verify the proposed method, a 1.16-19.2 GHz absorber was designed and manufactured, and the measurements agreed well with the EC and full-wave simulations.