Design of a Dual-Band Electromagnetic Absorber With Frequency Selective Surfaces

A dual-band electromagnetic absorber based on double-layer frequency selective surface (FSS) is proposed for broadband applications. The layer I is designed with an absorption performance at higher frequency and a transmission window at lower frequency. Simultaneously, the layer II is designed with an absorption performance at lower frequency and a strong-reflection window at higher frequency. Due to the low-pass property of the layer I, this layer is on the top of the absorption structure, allowing the incident waves to transmit to the layer II at lower frequency and be absorbed. Meanwhile, the incident wave is absorbed at higher frequency by the layer I since the layer II acts as the strong-reflection substrate in the bottom of the absorption structure. The reflectivity of absorber below -10 dB covers a bandwidth of 1.3-4.1 GHz and 7.2-10 GHz at normal incidence. Furthermore, the absorber can still maintain an absorption bandwidth below -10 dB at 1.4-4.1 GHz under the 30 degrees oblique incidence. The good agreement between simulation and measurement validates the proposed absorber.