DESIGN OF DUAL BAND FILTER BASED ON A NOVEL DGS STRUCTURE

This letter presents a dual-band bandpass fllter (BPF) using interdigital coupling lines with a new defected ground structure (DGS) pattern. Traditional DGS structures are mainly used to realize wide bandstop characteristics. In this letter, by introducing a pair of coupling stubs in the aperture of the DGS, a narrow passband can be achieved within a wide stopband, so a dual-band bandpass fllter can be implemented. An equivalent circuit model is derived to describe the fllter. And the circuit simulation result agrees well with the EM simulation one. The position and bandwidth of the two passbands can be designed and adjusted independently. In order to verify the theory, a dual-band bandpass fllter is designed, fabricated and measured. The simulated and measured results are in good agreement.