A Metasurface Based Dual Band Stop Filter at ISM Bands for Wearable Applications

This research proposes a metasurface (MS) based dual bandstop filter with sharp roll off and high bandwidths towards suppression of both the ISM bands at 2.45 GHz and 5.5 GHz. The unit cell of the MS comprises two patches: one outer metallic strip with protruding strips at the center directed inwards and an inner dumbbell- shaped patch with “H” shaped slots. To make it suitable for wearable biomedical applications, jeans have been chosen as the substrate in the design. The unit cell has dimensions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.23 \lambda_{0} \times 0.23 \lambda_{0}$</tex> with a substrate thickness of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.004 \lambda_{0}$</tex>. The electric field analysis and the angular stability of the filter have also been studied to find suitability for versatile applications. Further the filter has been checked for oblique incidence and found angularly stable up to 45° having ultrathin feature which made it suitable for biomedical application in ISM band.