A Micro Copper Mesh-Based Optically Transparent Triple-Band Frequency Selective Surface

Frequency selective surfaces (FSSs) are low-profile structures consisting of periodic elements that can manipulate the behavior of electromagnetic waves. In various fields, such as vehicular and indoor communication and personal electronic devices, their use as spatial filters is limited primarily due to safety and aesthetic reasons. A possible solution in this regard is using transparent conducting oxides or graphene on glass. However, the transmission performance of these filters is relatively poor as they inherently suffer from higher degrees of ohmic loss as compared to their opaque counterparts. Thus, we propose a suitable alternative that offers lower transmission loss with similar a transparency profile (76.2%) using copper mesh instead. The present letter discusses the design of an optically transparent triple-band bandpass filter that passes electromagnetic waves only at 2.4, 3.7, and 5.7 GHz and provides a minimum attenuation of 35 dB at transmission zeros. Investigations have also been carried out on the proposed structure under variations in both polarization (
$\alpha _{1}$
) and incidence (
$\alpha _{2}$
) angles. The designed FSS has wide angular stability and is fourfold symmetric. Thus, its filtering performance is largely unaffected under variations in polarization angle. A prototype of the proposed filter has been fabricated and experimentally tested for validating the simulation results, and a good agreement between them has been achieved.