Design of compact low pass filter with wide stop band using tri-section stepped impedance resonator

Abstract

This paper reports the design of a compact low pass filter (LPF) with wide stop band region using tri-section stepped impedance resonators in microstrip medium. Experimental results of a low pass filter designed at 1 GHz have been compared against the analytical and EM simulation results for the validation of the design. Results are satisfactorily matching each other. The maximum insertion of the measured filter is 0.2 dB and minimum return loss is 13.5 dB over the pass band. The stop band rejection is better than 20 dB from 1.5 GHz to 4.2 GHz and hence wide stop band performance is achieved. Overall size of the filter is 30 mm × 20 mm × 0.78 mm which is 0.1 λ × 0.066 λ × 0.0026 λ at 1 GHz.