A Metasurface-based Triple-band Polarization Insensitive Band-Stop Filter for S/C/X Band Applications

In the present work, a metasurface-based band-stop filter (BSF) has been designed and studied for applications in S, C and X bands. The single unit of the design comprises ring and plus-shaped metallic patterns made of copper layer on top of a FR-4 substrate while the backside is completely etched off. The proposed unit cell has a dimension on the order of $0.16\lambda \times 0.16\lambda$, making it compact in nature. When the electromagnetic (EM) wave is incident on the structure, band-stop characteristics have been observed at three distinct frequencies 2.67 GHz, 7.28 GHz and 9.71 GHz lying in S, C and X bands, respectively. The simulated results of the structure have been validated by the experimentally measured data. The design is ultrathin $(\lambda/68.67)$ referred to the lowermost stopband frequency. The transmission response of the BSF is nearly stable up to 45° incident angle for both transverse magnetic and transverse electric polarization of the incident EM wave. The BSF further exhibits polarization insensitivity property owing to the four-fold symmetry. The structure has been fabricated and the experimentally measured results have been found to be good agreement with the simulated ones.