A loop resonator for 3-D frequency selective structure

A loop resonator for the 3-D frequency selective structure is proposed aiming to reduce the thickness of the structure and introduce a new type of resonator inside the unit cell. The structure is based on the coupling between the two modes concentrated in the unit cell to obtain transmission and reflection zeros. The new resonator reduces the thickness of the structure by 28.5% compared to the previous structures, this resonator open the way for more resonators to be involved in. The proposed resonator shows stable performance under oblique angles of incidence for the single-band and dual-band structures. The operating concept and simulation results are included.