Design of dual band-notch UWB bandpass filter based on T-shaped resonator

In recent years, UWB bandpass filter has been key and essential component in UWB systems. This paper proposed a novel dual band-notch UWB bandpass filter based on T-shaped resonator. The proposed filter has realized dual band-notch function by coupling two T-shaped resonators to the basic UWB BPF, introducing dual notched bands with deep and sharp shirt and providing freedom to adjust the notch frequency. The basic UWB BPF is composed of microstrip lines and rectangular patch multiple mode resonator (MMR) having flat ultra-wideband response and sharp rejection skirt. The basic filter has four short-circuited stubs with length of λ/4, where λ is the guide wavelength of the central frequency. To reduce the size of the filter, the proposed BPF has been designed with fold branch to instead of the general branch, which can obtain good passband property with the UWB band range from 2.4 GHz to 10.9 GHz. The main advantages of the proposed filter is that dual center notch frequencies can be easily tuned to certain frequencies in a wide UWB frequency band, so f
_notch1
can be easily tuned from 2.4 GHz to 2.6 GHz and f
_notch2
can be easily tuned from 3.4 GHz to 8.3 GHz. The notch frequency of filters can changed by adjusting the size of T-shaped resonator stubs. The design parameters is optimized by 3D EM commercial software HFSS 13.0, and the simulation results indicated that the proposed filter based on T-shaped resonator can generate two notch bands at 2.4 GHz and 3.5 GHz. The proposed dual band-notch UWB bandpass filter based on T-shaped resonator can efficiently reduce the interference from undesired signals in WLAN and in WiMAX with certain application prospects.