A strong coupled microstrip ring resonator using linearly tapered feedlines for bandpass filter applications

A new feedline using linearly tapered microstrip lines to a microstrip ring resonator is proposed. The circular and rectangular resonators with the new feedlines have been simulated and implemented. The results show that the optimum feedline length is about /spl lambda//sub g//2 and the feeding angle trades off between the insertion loss and the fractional bandwidth. The insertion loss of the proposed one is enhanced by more than about 7 dB compared with the conventional one. The design of the bandpass filter using the new proposed feedline is presented.