A compact millimeter-wave dual-mode UWB microstrip BPF

A compact millimeter-wave dual-mode ultra wide-band microstrip bandpass filter is presented in this paper. This kind of filter uses hairpin resonator as its basic unit, and the input/output coupling structure can introduce transmission zeros at the both sides of the passband due to source/load (S/L) coupling. Short-circuited stub is loaded at the center of the hairpin resonator to form dual-mode resonator, which results in that a two order filter can produce four transmission poles in its wide passband. Simulation result shows good agreement with the coupling matrix synthesis result.