Size Reduction and Bandwidth Enhancement of a Waveguide Bandpass Filter Using Fractal-Shaped Irises

In this letter, a novel waveguide bandpass filter with fractal-shaped irises is presented. By applying first iteration Koch fractal-shaped irises, the bandwidth is increased to more than 3.15times and the overall size is reduced to about 2.8times in comparison to a waveguide filter with rectangular-shaped irises. The proposed filter is simulated using Ansoft HFSS and fabricated, which is verified by good agreement between simulated and measured results. Measurement results show less than 0.8 dB insertion loss and return loss better than 10 dB.