A Compact Microstrip Low Pass Filter Based on DGS with Shaped Microstrip Line

摘要

A triple U-shaped defected ground structure (DGS) with shaped microstrip line is investigated for compact low pass filter (LPF) applications. With this structure, the basic resonant element exhibits the elliptic-function low pass responses. The use of this structure allows sharp cutoff frequency response and high harmonic suppressions together with the small size to be obtained without the need for periodic DGS structures. The proposed DGS unit provides flat pass band characteristics and high stop band attenuation that can be controlled by the length of the opposite DGS.