Evolution of Low-Profile Ultra-Wideband Frequency Selective Surface with a Stable Response and Sharp Roll-Off at Lower Band for C, X and Ku Band Applications

This paper focuses on two different design flows of how an ultra-wideband FSS can be achieved from a narrow band structure. By amalgamating a capacitive patch with a corrugated square slot structure, as the first approach while the second approach involved designing a dual layer FSS by etching the corrugated square slot at both top and the bottom layer of the substrate. A 98% bandwidth extending from 5.5 GHz to 16 GHz was achieved using the first approach while the modified structure yields about 107% bandwidth covering up the entire range from 5 GHz to 16.5 GHz, hence improving the performance in terms of bandwidth. The final modified FSS structure manifests the polarization insensitive nature as well as angle insensitivity up to 60 degree angle of incidence in terms of the entire range of the wide reflection band, and covering all the three bands (C, X and Ku band). The transmission coefficient manifests a stable response below 20 dB almost throughout the entire band without significant variation. The measured result shows good agreement with the experimented result validating the fabricated prototype and measurement. The bandwidth can be tuned by varying different parameters like corrugation dimension, dielectric permittivity, substrate height which have been explained in this paper.