Performance enhancement of Salisbury screen absorber using resistively loaded spiral FSS

In this article, we show that the �10 dB reflectivity bandwidth of a Salisbury screen operating at normal incidence is increased by 56% when a lossy spiral shaped frequency selective surface is inserted between the outermost 377 X per square resistive sheet and the ground plane. Moreover, this structure exhibits significantly better angular stability and is suitable for suppressing radar backscatter simultaneously in the TE and TM plane. Reflectivity predictions for normal and 40� incidence are shown to be in close agreement with bistatic measured results over the frequency range 5.4– 18 GHz.