Modelling of defected structures and stub based compact ultra-wideband bandpass filter (UWB-BPF) with a single notched band.

In this article, a low loss and compact microstrip ultra-wideband bandpass filter (UWB-BPF) with a narrow-notched band is recommended for suitable applications in ultra-wideband wireless communication systems. The design methodology is presented to develop the microstrip structure of the UWB-BPF pursued by a single notched band (NB) in the passband of the UWB filter. An array of I-shaped defected ground structures and L-shaped defected microstrip structures based lowpass filters is cascaded with a shorted stub based highpass filter to achieve a UWB-BPF response. The two identically folded open stubs are loaded to obtain the narrow NB. The center frequency of the UWB-BPF without the NB is 3.5 GHz, and the stopband is suppressed up to 14.5 GHz. The fractional bandwidth achieved is 160%, with a circuit area of 0.11 ${\rm{\lambda }}_{\rm{g}}^{\rm{2}}$ λ g 2 . Furthermore, the single NB is attained at 5.7 GHz to reject interferences of signal from the 5G network with an attenuation level of 59 dB. The electromagnetic simulated and experimental responses of the designed structures demonstrate a well-matched behavior among them. The NB at 5.7 GHz in the UWB-BPF passband region suppresses the signal interference from the 5G network (5500 MHz), WLAN (5900 MHz), and WiMAX (5800 MHz). [ABSTRACT FROM AUTHOR]