Ultra-Broadband 3-D Absorptive Frequency-Selective Transmission Structure Using Commercial Absorber

In this paper, an absorptive frequency-selective transmission structure (AFST) with two-sided absorption bands and free of lumped elements is presented for the first time. The proposed design of AFST structure is realized by integrating commercial absorbers with bandpass and bandstop frequency-selective structures (FSSs) to produce a transmission band within a wide absorption band. An AFST prototype is designed and then fabricated. It is shown through the measurement that less than 0.8 dB insertion loss is obtained at 10 GHz with 12.8% bandwidth. Under the normal incidence, 10 dB reflection reduction is realized with 161.4% fractional bandwidth. A good agreement between simulation and measurement verifies the design concept.