Ultra Wideband Frequency Selective Surface for Microwave Band Applications

This paper is about creating and testing a special surface that can block specific frequencies of electromagnetic waves, and it's designed to work well regardless of the direction and polarization of the incoming waves. The unit cell of this FSS is composed of a square loop element combined with a crossed dipole featuring a circular groove element. Especially, the unit cell's size has been significantly reduced to 0.047 times the free-space wavelength (λ) corresponding to the lowest UWB frequency. The FSS in this work performs exceptionally well, as it has a bandwidth with a signal loss of -3dB that ranges from 3.05 GHz to 10.73 GHz. This bandwidth effectively covers the entire Ultra-Wideband (UWB) spectrum and the proposed FSS unit cell consists of a square-loop and a ring printed on opposite sides of a low-cost metamaterial substrate. Additionally, because of the small size of the individual unit cells in the FSS, it maintains its performance very well even when the electromagnetic waves hit it at angles as wide as 60 degrees, whether the waves have a perpendicular (TE) or parallel (TM) polarization.