Harmonic Suppression by Using Input and Output L-shaped Microstrip Lines For Dual-mode Resonator Filter Applications

摘要

This paper proposed a harmonic suppression using input and output coupled feed-lines for dual-mode resonator filter applications. The folded coupled feed-lines are coupled in the form of the L-shaped input and output feeders to the dual-mode resonator. Two opened-end feed-lines are added to enhance the upper stopband performances. The dual-mode resonator operates at 1.95 GHz, which is found that an insertion loss is less than 0.6 dB and a return loss is better than 25 dB. A proper tuning length for the input/output feed results in a high rejection level which a signal suppression is better than 20 dB over a frequency band from 2.2 GHz to 4.5 GHz.