Synthesis and Design of SIW Bandpass Filter With Impedance Transformation for Filtering Antenna

This paper summarizes the synthesis method of a bandpass filter with different matching loads on two ports based on the traditional synthesis method of Chebyshev bandpass filter. A fourth-order substrate integrated waveguide (SIW) bandpass filter with different loads on two ports is proposed in this paper in order to demonstrate the theory. The bandpass filter consists of four resonators and the four resonators are arranged in a square pattern, which makes the filter more compact overall. The result shows that it can get a better match result by renormalizing the output port from 50 $\Omega$ to the specified impedance. According to the synthesis method of asymmetric two-port bandpass filter, the extra matching stubs can be avoided between the filter and its load. Thus, it can meet the needs of miniaturization design for filtering antenna.