Miniaturized bandpass substrate integrated waveguide filter with frequency-dependent coupling realized using asymmetric GCPW discontinuity

An asymmetric GCPW discontinuity is proposed to provide frequency-dependent coupling in microwave bandpass filters. Wider and narrow sections introduce, respectively, the capacitive and inductive component to the equivalent circuit representing coupling. By selecting the dimensions of the discontinuity and width of the inductive window in substrate integrated waveguide, an additional transmission zero can be introduced at prescribed positions. A distinct feature of the proposed structure is a small footprint and low loss. As an example, a bandpass filter with a central frequency of 4.6 GHz and a 200 MHz passband is designed, and its performance is measured. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1818-1821, 2015