Design of wide dual-passband microstrip bandpass filters with comb-loaded resonators

Novel microstrip bandpass filters with comb-loaded resonators are proposed. With comb-loaded resonators, the proposed bandpass filter can have a wide passband. In particular, dual passbands show up around 2.45 GHz and 5.75 GHz and their bandwidth is 780 MHz. In addition, by properly controlling passband´s coupling coefficient, two passbands´ bandwidths of the dual-passband bandpass filter will be controlled properly. Finally, the agreement between measured results and the theoretical prediction validates the proposed structure.