A miniaturized quad-band frequency selective surface for C-band applications

In this paper, a low-profile quad-band frequency selective surface (FSS), designed as a sub-reflector for satellite communication is presented. This single layered FSS employs non-concentric open loops with controlled field coupling to provide four closely spaced transmission zeroes within the C-band. The proposed design approach occupies lesser metallized area which gives an additional benefit of frequency tuning while retaining the miniaturized cell dimension. The four band-stop center frequencies are 4.6, 5.5, 6.3 and 7.3 GHz with an average bandwidth of 240 MHz. The unit cell has a miniaturized dimension of 0.138 $ \lambda _{0}\times $ λ0×0.138 $ \lambda _{0}\times $ λ0×0.012 $ \lambda _{0} $ λ0, where $ \lambda _{0} $ λ0 stands for free space wavelength at the lowest resonating frequency. The FSS provides angularly stable frequency response up to $ 45^{\circ } $ 45∘ for TE as well as TM polarization. Additionally, the FSS can be mechanically tuned to allow either TE or TM polarized wave. This study also reports the outcomes based on parametric variations and verifies the frequency behaviour of the structure using a circuit model. The simulated results are validated by testing a design prototype of the proposed FSS. Good concordance is observed between the simulated and measured results.