DUAL-MODE BANDPASS FILTER USING TRIANGULAR PATCH RESONATOR WITH INVERTED T-SHAPED SLOT

摘要

This article presents a miniaturized dual-mode narrow bandpass filter using an equilateral triangular patch resonator with an inverted T-shaped slot, which exhibited a size reduction of 37% compared with a single-mode equilateral triangular patch at the same frequency. Two- and four-pole dual-mode bandpass filters were designed and fabricated with this new resonator. Experimental results with the two-pole filter centred at 7.76 GHz showed a fractional bandwidth of 4.5%, return loss better than 17.8 dB, and minimum insertion loss of 2.2 dB. The results of the four-pole filter showed a fractional bandwidth of 3.5%, return loss better than 16 dB, minimum insertion loss of 2.6 dB, and a good second harmonic band rejection.