An Ultrathin Multiband Chiral Metasurface for Transmission and Asymmetric Absorption of Electromagnetic Waves

This article presents an ultrathin chiral metasurface which can exhibit multiband asymmetric absorption as well as symmetric transmission in a specific frequency band outside the absorption regions. Unlike most electromagnetic metasurface absorbers, the proposed structure does not have a continuous conducting sheet at the bottom which also allows it to act as a bandpass spatial filter. The metasurface has a substrate thickness of only lambda high/62.5 and lambda low/34 at the highest and lowest operational free-space wavelengths, respectively. The transmission band is centered at 5.5 GHz, and the asymmetric absorption bands are centered at 3, 3.33, and 4.5 GHz, respectively. The operational bands can be tuned as per user requirements. The metasurface has an angular stability of 45 degrees for both TE and TM incidence. It can be used for radar cross-section (RCS) reduction, electromagnetic shielding, and as a spatial bandpass filter.