Band Notched UWB-BPF Based on Broadside Coupled Microstrip/CPW Transition

A planar band notched ultra-wideband (UWB) bandpass filter based on broadside coupling of microstrip/co-planar waveguide (CPW) transition is proposed and implemented. The UWB filter topology is made up of microstrip lines on the top coupled in broadside fashion to an open ended CPW in the ground plane. Dual narrow notches at 5.2 and 7.9 GHz are implemented by etching two meander shaped defected ground structures in the CPW under the microstrip lines. A wideband stopband for improved isolation is obtained with the suppression of spurious harmonics by the attenuation poles generated by the spur line structures embedded in the input and output feeding lines. The proposed structure exhibits good frequency characteristics and is of compact size.