Design of miniaturize flexible wideband frequency selective surface for electromagnetic shielding application

In this paper, a flexible, ultra-thin, miniaturized broadband frequency selective surface (FSS) is demonstrated for wideband electromagnetic shielding application. The unit cell of the proposed FSS structure consists of cross dipoles loaded with the metallic circular strip. The proposed miniaturized FSS structure has an extremely low profile with a thickness of 0.0009 lambda(o) and a unit cell size of 0.045 lambda(o) x 0.0450 lambda(o). This FSS structure provides wideband shielding of more than 20 dB from 1.1 to 2.6 GHz frequency region. Besides this wide stopband, the FSS structure acts as a transparent window in the n78 frequency band which can be used for the 5G communication purpose. Moreover, by comprehending the interaction between the incident electromagnetic wave and unit cell, a conceptual equivalent circuit model is developed that helps to interpret the mechanism of the miniaturization as well as the broadband response of FSS structure. We also compared the proposed FSS with other recently reported structures and observed more than 55% improvement in size reduction with several other miniaturized flexible FSS structure. Furthermore, this FSS structure exhibits 20 dB attenuation over a wide frequency region with a fractional bandwidth of 111%. Moreover, excellent resonant stability is achieved in regards to different polarization and incident angle up to 60 degrees.