Design of two-band band-pass filter using defected ground structure (DGS) resonators

This paper introduces folded DGS resonators to be used as building blocks of two-band band-pass filter. The transmission line with defected ground structure (DGS) can increase the equivalent capacitance and inductance of the transmission line and the dielectric constant. This character is useful for the design of miniaturization filter. The folded DGS resonator is then applied to design a multilayer second-order coupled resonator band-pass filter and a second-order two-band band-pass filter. The simulation results are presented to show the performance of these filters. It is easy to change the work frequency by adjusting the length of folded line and the thickness of resonator. External Quality Factor is connected with the length of feed line. It is significant for the research of the multi-frequency DGS filter.