An FSS Based Dual-band Bandstop Filter for Minimizing Interference in C Band Satellite Downlink Communication

Over the decades, C-band frequencies have gained popularity in various wireless systems including mobile, radar, and satellite communications. However, this frequency band suffers from substantial interference due to sharing of its spectrum with Broadband Wireless Access networks and several operational VSATs. This paper presents a dual-band bandstop filter implemented using frequency selective surface (FSS) for minimizing interference in the C band downlink satellite system. The dual-band FSS unit cell is designed using a circular ring with rectangular slots on the top layer and a Swastika symbol at the bottom, which has a dimension of 0.32λ
0
×0.32λ
0
(free space wavelength at 6 GHz). The performances of the proposed filter in terms of transmission coefficients, reflection coefficients, surface current distribution, and angular stability are analyzed. The results demonstrate that the filter resonates at two distinct frequencies of 5 GHz and 7.2 GHz within the C band. It is revealed that the dual-band filter exhibits angular stability up to 30° in both TE and TM mode polarizations.