Double-Polarized Dual-Passband Absorptive Frequency-Selective Transmission Structure

Double-polarized dual-band absorptive frequency-selective transmission structure (AFST) is presented, which has two passbands within a wide absorption band. Equivalent circuit models (ECMs) are presented to assist the structure design efficiently. Based on the verified ECMs, practical AFSTs are then constructed accordingly. One single-band AFST is first designed, which is realized by introducing slot and cross-frame slot (CFS) resonators in the lossy and lossless layers of one broadband absorber, respectively. As a result, one passband is achieved, while the absorption at both sides is maintained. Furthermore, by using multiple slots and CFS resonators with different resonant frequencies, two transmission poles are, respectively, achieved at 3.5 GHz and 4.9 GHz, and the dual-bandpass performance is achieved. Under normal incidence, the operating frequency bands (reflection <-10 dB) of the proposed AFSTs are larger than 110%, while the minimum insertion losses are less than 0.25 dB. For demonstration, one prototype of the dual-band AFST is fabricated and measured, and a reasonable agreement between the simulated and measured results is observed.