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

Novel wide-single-/dual-passband bandpass filters with comb-loaded resonators are proposed. With the comb-loaded resonators, wide single/dual passbands appear. In particular, dual passbands show up around 2.45 and 5.75 GHz and their bandwidth is 780 MHz. Furthermore, because of the uniplanar structure, the proposed filters are compact and can be fabricated on a printed circuit board. Design equations are provided. The agreement between measurement and the theoretical prediction validates the proposed structure.