Dual-band frequency-selective rasorber with embedded interdigital capacitors

A dual-band dual-polarized FSR is proposed in this paper. The structure consists of two layers, a resistive layer and a lossless layer. The units of the resistive layer are designed based on the Jerusalem cross and absorbing waves are achieved by mounting resistors on the metal arms. the double-ring interdigital capacitor structures are embedded in the center of the cross to generate two parallel resonances, resulting in two transmissive windows. The lossless layer is designed for double bandpass by etching double square slots. The two layers transmit electromagnetic signals in two passbands and form absorbers outside the passbands to produce two absorption bands. The simulation results show that the reflection coefficient of the proposed FSR is under -10 dB from 2.96 to 10.31 GHz, and the fractional bandwidth is 110.8%, while the FSR has a stable performance within 40°. The equivalent circuit model of the FSR is also illustrated. Furthermore, the FSR is processed and the measurement results verify the design. The measurement results demonstrate that the insertion losses of the passbands are -0.35 dB and -0.2 dB at 5.91 GHz and 9.67 GHz.