Design and Fabrication of a Compact Microstrip Low-Pass Filter with Sharp Transition Band and High Suppression Factor

In this paper, a compact microstrip resonant cell is proposed. Designed based on the hairpin structure, the proposed resonator provides wide stop-band and sharp skirt for low-pass filters. By cascading two of these resonators, a microstrip low-pass filter with cut-off frequency of 1.69GHz is designed and fabricated. According to experimental results, this filter has a small normalized circuit size (0.0108), low insertion loss (less than 0.2dB), wide stop-band from 1.78GHz to 10GHz defined by -20dB attenuation level, and sharp roll-off (308dB/GHz).