Design of a novel compact lowpass filter with defected ground structure and open stubs

A novel lowpass filter(LPF) with compact size, which contains a pair of symmetrical dumbbell ring shaped defected ground structure (PSD-DGS) and compensated microstrip line with open shunt stubs, is presented in this paper. Sharp cut-off characteristics is obtained by the PSD-DGS, while the compensated microstrip line is used to reduce the loss of passband. Moreover, open shunt stubs is implemented to suppress harmonics and expand the stopband. Therefore, the compact lowpass filter has plenty of advantages like flat passband, sharp cut-off and wide stopband, as well as low cost and easy fabrication.