UWB filter with controllable notch band and higher stop band transmission zero using open stub in inverted T-shaped resonator

A novel ultra wide band (UWB) bandpass filter (BPF) having controllable notch band and controllable higher stop band transmission zero is presented in this paper. It has excellent band-to-band rejection. It is based on the filter of microstrip lines and Inverted T-shaped multiple mode resonator with open stubs. Interdigital input/output coupled lines are used for coupling to the inverted T-shaped resonator of the main transmission line of BPF. Even and odd mode analysis has been performed to analyze the structure. One notch band is achieved between two passbands by electric or magnetic dominant coupling and it is controlled by using open stubs in inverted T-shaped resonator. Also higher stop band transmission zero is controlled by these open stubs. The proposed UWB filter has the advantages of being compact with a notch band to achieve desired pass bands by controlling the length of the stubs connected to MMR. The proposed UWB BPF achieved insertion loss of 0.66 dB and 2.25 dB at 5.5 GHz and 9 GHz, respectively. UWB passband exist from 3.145 GHz to 5.68 GHz and from 7.045 GHz to 11.01 GHz with one notch band at 6.1 GHz.