Absorptive Frequency-Selective Reflection and Transmission Structures

Tailoring methodology is proposed in this communication to achieve an arbitrary frequency response within a wide absorption band. An ultrawideband (UWB) absorber utilizing multiple resonances in the unit cell of 3-D frequency-selective structure is utilized as the textile for the proposed designs. Two types are proposed: one is absorptive frequency-selective reflection structure (AFSR) and the other is absorptive frequency-selective transmission structure (AFST). These structures have reflection/transmission band within a wide absorption band. Two prototypes are designed, fabricated, and measured to validate the proposed methodology. The first one is an UWB absorber with 155.7% absorption bandwidth from 1.8 to 14.4 GHz with structure's thickness of 0.12.0 at the lowest absorption frequency. The second one is an AFST with wide absorption bands at both sides of its transmission window. It exhibits 54% and 76% for the lower and upper absorption bands, respectively, with 1 dB insertion loss in the transmission window. A good agreement is achieved between simulation and measured results.