Improvement of harmonic responses of a /spl lambda//4 resonator BPF with tap-connection technique

Improvement of harmonic responses for a /spl lambda//4 resonator bandpass filter (BPF) using a microstrip line (MSL) is carried out. Firstly, a basic mechanism for improving the harmonic responses of the /spl lambda//4 resonator under the condition that the excitation procedure is changed. Secondly, a BPF on the basis of our proposal is presented, as an example. It is confirmed that the /spl lambda//4 resonator with the tap-connection technique is of great use for improving the harmonic responses of the microwave filters.