Design of Microstrip Cross-Coupling Bandpass Filter With High Selectivity and Stopband Suppression Using Internal Coupling SIRs

A compact microstrip cross-coupling bandpass filter with high selectivity and enhanced stopband suppression is presented in this paper. The source-load parallel open-circuit coupling line is introduced to increase a tunable transmission zero near the passband, which improves selectivity and reduces the amplitude level of stopband. From the simulation results, the novel filter has the advantage of high rectangle factor, low insertion loss, great stopband suppression and miniaturization.