Miniaturised frequency selective surface based on 2.5-dimensional closed loop

A novel frequency selective surface (FSS) has been designed based on 2.5-dimensional (2.5D) closed loop for miniaturisation. Compared with the previous FSSs in the literature, the proposed FSS is smaller (0.048λ₀ × 0.048λ₀) and shows almost the same transmission coefficient for different polarisations and incident angles. A prototype of the proposed FSS has been fabricated and measured. The results of the experiment show a consistency with the simulated ones.