A novel SIW dual-band bandpass filter on a double-layer substrate using loaded posts

A novel substrate-integrated waveguide (SIW) dual-band bandpass filter fabricated on a double-layer substrate is presented in this article. Each layer uses two rectangular cavities to create a passband, so the two individual bandpass filters are formed by setting the different locations of loaded posts for dual-band operation, that is, 4.6 and 5.3 GHz. In design, the coupling between the upper and lower layers is realized via two slots on the middle metal layer between two substrates. The double-layer structure not only provides a degree of freedom to control the center frequency of two passbands, but also improves the out-of-band rejection skirts with the help of produced transmission zeros. In final, the proposed SIW bandpass filter is fabricated to prove the predicted results in experiment, and good agreement is obtained. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:155-158, 2016