Fractal-shaped microwave passive circuits offer a great deal of promise for achieving good performance in small circuits. In this paper, isosceles right-angled triangular patch resonator with fractal hole is analyzed, and new single band and dual-band RF filters by using isosceles right-angled triangular patch resonators with fractal pattern are proposed. It is shown that with the assistance of a fractal, the right-angled triangular resonator can be miniaturized and filter performance is greatly improved, simultaneously, resonance of the resonator higher order mode is enhanced, which is helpful for a dual-band filter implementation. Two proposed fractal bandpass filters are fabricated, and their performance is verified by measurement. The proposed filters demonstrate the applications of right-angled triangular patch resonator and exhibit advantages of a simple structural topology and compactness, which are essential in RF circuit design.
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