New compact bandpass filter using Minkowski-fractal microstrip line

New bandpass filters based on Minkowski-fractal microstrip line are proposed with operation frequency of 5-6GHz and passband insertion loss of no more than 0.5dB. This novel microstrip line presents bandpass performance without any assistance of branches or resonators, and the undesired spurious response which worsens the skirt properties is suppressed with the assistance of the Minkowski fractal geometry. The fractal also decreases the 3-dB bandwidth and cutoff frequency. The filter has compact and miniature size of no more than 30×2.5mm². Key words: Minkowski fractal, bandpass filter, harmonics suppression, miniaturization.