An Ultra-Wideband Multilayer Absorber Using an Equivalent Circuit-Based Approach

An ultrawideband (UWB)absorber designed by equivalent circuit model (ECM) is presented in this article. The structural parameters of multilayer absorbers were calculated for full-wave simulation so as to verify the accuracy of this method. The simulation results illustrated that the ideal frequency response can be easily and quickly obtained by using ECM, such as single narrow absorption band, dual-band absorption peak, and ultrawide absorption band. A 20 x 20 quadruple-layer absorber was fabricated and tested, which obtained 10 dB radar cross section reduction (RCSR) from 2.1 to 37.5 GHz with bandwidth ratio (BWR) of 17.62:1. The overall dimension of the unit cell structure is 280 x 280 x 14 mm3 (1.96 lambda(max) x 1.96 lambda(max) x 0.098 lambda(max)), and the absorber exhibits stable response on conformal cylinders with central angles of 30 degrees and 60 degrees. Moreover, in order to reduce the influence of high-order modes above U-band, the space mapping (SM) technique was introduced to optimize the absorber's parameters, which greatly expanded the high-frequency absorption bandwidth. A 10 dB RCSR was achieved from 3 to 94 GHz with BWR of 31.33:1.