AbstractThis work proposes and investigates a wide‐angle band‐pass frequency selective surface (FSS) with two sharp sidebands. The presented FSS element is made up of three metallic layers and two substrate layers in between, which are surrounded by a substrate‐integrated waveguide (SIW) cavity. The top metallic layer is identical to the bottom layer, composed of a square patch etched with a hexagonal groove, while the middle layer is a similar patch but with rectangular notch edges. This structure achieves a second‐order band‐pass response with highly frequency selectivity on either side of the passband. At the same time, this FSS demonstrates excellent stability for both transverse electric and transverse magnetic polarizations with incident angles between 0° and 60°. The electric current and field distributions are demonstrated for deep analysis. Furthermore, an equivalent circuit model is developed to further understand the operating mechanisms. To verify the validity of the design, we construct a prototype of the SIW‐based FSS (SIW‐FSS) and measured it. There is a fair degree of agreement between the measured and simulated results. Finally, we loaded it onto the horn antenna and tested its application in filtering antennas.