A compact triple‐mode bandpass filter based on isosceles right‐angled triangular resonator.

In this letter, a triple‐mode bandpass filter based on isosceles right‐angled triangular (RAT) resonator with three magnetic walls is proposed. To realize the triple‐mode filter, the RAT resonator is perturbed by two metalized via‐holes around the center. These via‐holes form an LC resonant unit with the patch. Also, the via‐holes make mode shifting of the TM010Z mode while not affecting the TM110Z mode in order to form the passband. The proposed filter is fabricated and measured. The center frequency is 5.51 GHz and the fractional bandwidth is 20%. The minimum in‐band insertion loss and return loss are measured to be 1.26 dB and 20.5 dB. The measurement results show that the filter has featured both compact size and excellent in‐band responses. [ABSTRACT FROM AUTHOR]