An ultra wide band filter with high selective dual notching

This paper introduces an ultra-wide band (UWB) band pass filter (BPF) with a coupled T-shaped stub. The filter's lower cut-off frequency and higher cut-off frequency are around 3.2 GHz and 9.7 GHz respectively. Moreover, the pass band exhibits two narrow notches at 5.9 GHz and 7.8 GHz which minimize the interference effects of the proposed filter with both the wireless local area network (WLAN) and SATCOM systems, respectively. The main pass band of the filter and the upper notch are implemented using a stepped impedance resonator, coupled with an inter-digital feeding line backed by defected ground structures (DGS) for coupling augmentation. The lower notch band is implemented using a stepped impedance stub that is grounded through a via hole at one end and coupled to the main filter form at the other end. The proposed filter features a small size of 0.443× 1.534 λ
_g
²
.