A Dual-Layer Radar Absorbing Material With Fully Embedded Square-Holes Frequency Selective Surface

A dual-layer radar absorbing material composed of a square-hole dielectric (SHD) layer and an integrated absorbing layer that contains a square-hole frequency selective surface (SHFSS) was designed and fabricated. The obtained materials exhibited two absorption peaks with their reflection loss below -10 dB in 7.74-18 GHz. The detailed simulations and impedance analysis revealed how these peaks were produced and how their absorbing intensities can be enhanced. The power loss density, and electric- and magnetic-field distributions were proposed to explain the resonance mechanisms of the two peaks. It is concluded that the frequency depends on the dimensions of both SHD and cross-shaped wires on SHFSS, suggesting that the variation in 2-9.2 and 9.2-18 GHz is essentially independent. Notably, compared to the pure carbonyl iron powder absorbent, the average absorption intensities observed in the current materials with designed structure increased by 45.8% in 7.74-18 GHz, and the volume fraction of absorbent decreased to 56.1%.