Bandpass filter design using an open-loop defected ground structure resonator

This paper deals with a bandpass filter design using defected ground structure (DGS). An open-loop slot resonator is investigated and its parameters are extracted. After that, a bandpass filter is designed using coupled DGS and microstrip resonators. The combination of DGS and microstrip resonators allows use top and bottom side of the microwave substrate, therefore the resonators can partially overlap and desired coupling coefficient can be easily achieved. Finally, a sixth order BPF is designed, fabricated and measured.