Dual-wideband bandpass filter for ultra wideband applications

Novel dual-wideband bandpass filters are proposed by employing hybrid shunt short/open stubs in this paper. Transmission line model is established for analyzing and designing proposed BPF. Shunt open stubs are integrated between adjacent hybrid shunt short/open stubs to suppress out-of-band harmonic response. As demonstration, a dual-band bandpass filter cantered at 3.79/8.55 GHz is designed, fabricated and tested. Two transmission zeros are introduced in stopband to improve the rejection level between two passbands. Experiment is used to verify the designed prototype which has 3dB bandwidths of 70.71%/49.12%. Good agreements between full-wave simulated and experiment results are presented.