An Ultra-Wideband Balanced Bandpass Filter Based on Defected Ground Structures

An ultra-wideband (UWB) balanced bandpass filter (BPF) is proposed and designed using defected ground structures (DGSs). A multimode resonator on top layer with a coplanar waveguide on bottom layer is used to design a UWB BPF. U-shaped and H-shaped DGSs loaded with capacitor are used to design to provide common mode rejection within a lower band, while a set of dumbbell-shaped DGSs are utilized to provide common mode rejection within an upper-band. The proposed UWB balanced BPF shows the performance of good common mode rejection in and out of the UWB passband.