High-selectivity frequency selective surfaces at millimeter-wave and terahertz frequencies

Aperture-coupled resonators (ACRs) are applied to realize high frequency-selectivity bandpass frequency selective surfaces (FSSs). In the ACR FSS structures, identical patch resonators on the top and bottom layers are coupled through coupling apertures etched on a conducting plane in between. Multiple coupling paths between the resonators result in two transmission zeros on either side of the narrow passband, thereby realizing high frequency selectivity and suppressing the sidebands. Due to the symmetric structures and low profiles, the ACR FSSs exhibit superior stability to various incident angles and polarization states. For demonstration and potential applications, two ACR FSSs were designed at millimeter-wave and terahertz (THz) frequencies respectively. The standard printed circuit board (PCB) processing technology and the microfabrication technology were adopted to fabricate the proposed FSS structures. The measured results agree well with the simulated ones, thus verifying the proposed design.