Investigation on Bandpass Frequency Selective Surface Based on Aluminum Honeycomb Cavity

This letter proposes an innovative sandwich frequency selective surface (FSS) that integrates the periodic hollow architecture of aluminum honeycomb with cavity resonance. First, the resonant characteristics of the hollow honeycomb cavities are investigated. A 33% cavity miniaturization can be achieved by converting cavity sidewall boundaries from perfect electric conductor to perfect magnetic conductor (PMC) conditions. Then, a slot structure located at the two boundaries of the honeycomb cavity is introduced to provide slot resonance and act as an equivalent PMC wall to excite the TM_0,2/3,0 mode of the cavity. Finally, a dual-pole bandpass FSS with a center frequency of 7.07 GHz is achieved, featuring a small thickness of 0.059λ₀. The electromagnetic-mechanical properties of aluminum honeycomb-based FSS were fabricated and measured to validate the proposed design strategies. Mechanical tests revealed compressive strength exceeding 2.1 MPa with a density of 0.702 g/cm³, highlighting its lightweight and load-bearing advantages.