A Tri‐band Complementary Frequency Selective Surface with Very Closely Spaced Resonances

This paper presents a tri-band complementary frequency selective surface (CFSS) with very closely spaced bands and angular stability. The proposed CFSS element geometry is composed of double concentric rings. The choice of this geometry is because of its very good angular stability. The gap between resonance frequencies is very close, only 404 MHz from the first to second band and 202 MHz from the third to second, which is only possible because of the use of CFSS. The CFSS simulation is performed using HFSS software and the design used the equivalent circuit method. The simulated results are compared with the experimental ones for validation purposes. A very good agreement is observed between the simulated and measured results.