Substrate integrated waveguide dual‐stopband filter

A dual-stopband filter in substrate integrated waveguide (SIW) technology is presented. The filter uses a uniform SIW transmission line loaded by three quarter-wavelength H-plane stubs spaced by quarter-wavelength sections. The two stopbands contain three transmission zeros (TZs) each and are located at center frequencies of 10 and 12.2 GHz with corresponding bandwidths of 360 and 500 MHz, respectively. The center frequency and bandwidth of the passband, separating the two stopbands, are 11.03 and 1.26 GHz. A capacitive post is used to improve the return loss of this passband and the location of its reflection zeros (RZs). The filter is prototyped and measured, and good agreement between measured and simulated results is obtained. The measured results confirm the predictions in terms of locations of TZs and RZs as well as passband return loss and stopband attenuation levels. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1561–1563, 2014