A Metasurface-based Dual Passband Filter in L- and S- Bands for Space Communications

This research introduces a metasurface (MS)based, single-layer, dual-band, low-loss, sharp roll off bandpass filter (BPF) in L- and S- bands for space communication. The device exhibits high out-of-band attenuation with more than 35 dB and low insertion loss of 0.45 dB and 0.59 dB at 1.39 GHz and 2.78 GHz respectively. Employing FR4 substrates (relative permittivity of 4.4 and loss tangent of 0.02), the proposed MS filter offers high selectivity with roll off factor of 39.15 dB/GHz, reduced dimension with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.2 \lambda_{0}$</tex> periodicity and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.0037 \lambda_{0}$</tex> thickness. Narrow bandwidths have been achieved at the two frequency bands with 0.3 dB bandwidths of 0.08 GHz and 0.09 GHz respectively. The filter provides consistent response up to 90° under polarization variation due to its four-fold symmetric structure, making it applicable in space communication and navigation systems.