A Compact Ultra-wideband Band-pass Filter Integrated with Dual Tunable Notch Bands

A novel ultra-wideband band-pass filter integrated with dual tunable notch bands is proposed on the basis of the symmetric structure and open-ended stubs on top of the substrate. The dual notch bands are realized by symmetric structure on the substrate. By tuning the parameters of these stubs, the proposed UWB filter can operate from 2.9 GHz to 10.6 GHz, except for the bandwidth of 3.3-3.6 GHz for WiMAX application and other applications. The coupled-line sections can improve the bandwidth of the UWB filter, which act as inverter circuits in this design. Stepped impedance lines are used to form the basic resonators. A folded cross-coupled feeding structure is used to mimic the size and open-ended stub is employed to enhance the performance of the band-notched function. The filter is printed on a Roger-SRO 4003 substrate with the dimensions of 15 x 0 x 0.508mm and relative dielectric constant of 3.38.