Very Closely Located Dual-Band Frequency Selective Surfaces via Identical Resonant Elements

Very closely located dual-band frequency selective surfaces (FSSs) are proposed in this letter. The ratio of two operating bands can be as low as 1.06. The proposed FSSs comprise simply a single-layer metallic pattern on a thin dielectric substrate. The mechanism to achieve the low ratio between two operating bands is attributed to two separated resonant modes caused by four identical elements in a unit cell. Asymmetrical meandered pattern is introduced to improve stability of frequency responses with respect to incident angles. Moreover, the ratio of the operating bands can be tuned through rotation of the elements with ratios in the range from 1.06 to 1.10. In order to validate the designs, the prototype of the dual-band FSSs has been fabricated and tested. And the measured results show good agreements with the simulated ones.