Design and performance improvement of lowpass filter by using Defected Microstrip Structure

In this paper, an elliptic-function lumped element lowpass filter is proposed and designed. The proposed LPF provides cut-off frequency at 1GHz and attenuation pole at 1.06 GHz with good sharpness factor and negligible passband insertion loss. Finally, the attenuation bandwidth is improved by the removal of spurious transmission peak which is occurs at about 3.2 GHz using 50 ohm microstrip line with spiral-Shape Defected Microstrip Structure (DMS). The designed filter is useable in modern microwave and millimeter wave communication systems.