Flexible Ultrathin Frequency Selective Surface Dual-Band with Passband Response

In this paper, we proposed a novel ultrathin frequency selective surface with logarithmic spirals. The passband resonant frequencies of this proposed single-layer FSS are at 3.46 GHz and 10.22 GHz. A stopband with a deep null, at 6.98 GHz, separates these bands. The stopband has a bandwidth of 3.52 GHz. The −10 dB of the stopband are at 5.10 GHz and 8.62 GHz. The two passband resonances are 3.46 GHz and 10.22 GHz. The −3 dB bandwidths are 1.28 GHz and 1.62 GHz, respectively. In addition, we printed the FSS on a thin, flexible polyamide substrate. The proposed FSS has a thickness of 0.005 mm (0.0015λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf>), where λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> is the wavelength of the lower operational frequency. We compared the simulated results with the experimental ones for validation purposes. We can observe a good agreement between results.