COMPACT BANDPASS FILTER WITH SPURIOUS PASSBAND SUPPRESSION USING DEFECTED GROUND STRUCTURE

摘要

In this article, a novel and compact hairpin bandpass filter (BPF) using defected ground structure (DGS) is discussed. By placing a novel cascaded z-slot DGS at the location of the input and output port, the first spurious passband can be rejected. The elaborate analysis of the z-slot DGS has been given. The equivalent circuit of the z-slot and how the dimension affects the frequency response are presented. In addition, as the DGS is etched on the backside of the substrate, no extra size is added to the final layout. The experimental results demonstrate that this filter has low insertion loss, small size, and with a rejection level of more than 35 dB for the first spurious passband. The measured results of the proposed BPFs are in good agreement with the simulated ones.