Multiple mode resonance BPF design using suspended stripline with source-load coupling structure

A multiple-mode resonance bandpass filter of suspended stripline structure is proposed in this article with a source-load coupling feed design. Equivalent quasilumped elements circuit model is developed to represent the proposed filter's discontinuities and to emulate its frequency responses. The odd- and even-mode equivalent half circuits extracted from the derived LC circuit model are also examined for analyzing the circuit's mode resonances. Multiple resonances, which relate to two odd modes and two even modes, are observed. The circuit's physical layout of the proposed filter is guided by the LC circuits, and then the circuit's dimensions are optimized by sonnet simulation. Experiment is conducted to verify the filter's performance and agreements between the simulations and the measurements are observed.