Frequency-selective surfaces with two sharp sidebands realised by cascading and shunting substrate integrated waveguide cavities

Frequency-selective surfaces (FSSs) with two sharp sidebands have been investigated, which are constructed by cascading and shunting two substrate integrated waveguide cavities (SIWCs) of different sizes with periodic slots at top and bottom metal surfaces. The lower and upper sharp sidebands are induced by two transmission nulls that are generated by coupling between the slot aperture resonance and the resonances in the two cavities. Samples of the shunted SIWC-FSS with different size cavities were fabricated. Measured results are in good agreement with the predicted ones and its performance, such as high selectivity and passband bandwidth, is stable at oblique incidence.