Frequency selective surface based on quarter-mode substrate integrated waveguide technology with good parasitic passband suppression

A frequency selective surface (FSS) based on quarter-mode substrate integrated waveguide (QMSIW) is proposed and studied in this paper. The periodic unit is made of the QMSIW cavity and "L" type slots etched on the top and bottom surfaces. The slots not only perform as a part of the FSS element, but also realize magnetic walls to construct the QMSIW. Based on this miniaturized FSS cavity and its high-mode suppression ability, the stopband bandwidth can be expanded approximately twice compared with a conventional SIW FSS at the operation band. As an example, an X-band QMSIW FSS is designed and measured, which validates the correctness of our design. Besides, it is insensitive to the incident angle and polarization of the incident wave.