Design of Dual-passband Frequency Selective Surfaces Based on Metal Honeycomb Structures

Dual-passband frequency selective surfaces (FSSs) are presented in this paper. The proposed FSSs are designed and constructed with three-dimensional (3-D) metal honeycomb cavity in the middle and two-dimensional (2-D) planar slots as bottom and upper skin, forming a sandwiched structure. The slot elements at the skin structures are etched near the boundaries of metal honeycomb elements, which not only play a role in exciting aperture resonance, but also act as equivalent magnetic walls, exciting 2/3 of the TM
010
mode of the metal honeycomb cavity as a kind of hexagonal cavity. The miniaturization of the single-passband metal honeycomb cavity FSS is achieved, with high oblique incidence stability and low passband insertion loss. The presented single-passband FSS allows for relatively independent control of cavity resonance and aperture resonance, achieving different bandwidths. It is also possible to achieve free regulation of the out of passband transmission zero point by controlling the positive and negative coupling between cavity resonance and aperture resonance. Based on the above advantages, dual-passband FSSs with transmission zero points at different positions are designed by increasing the number of slots at the skins. Simulation results show good dual-band filtering response and stable oblique incidence response. The proposed honeycomb sandwiched FSSs have the advantages of lightweight, strong load-bearing, nonflammability, high temperature resistance, etc.