Microstrip coupled line bandpass filter using quasi minkowski fractal shape for suppression of the second harmonic

In this paper microstrip coupled line band pass filters using quasi minkowski fractal geometry is studied. Although conventional microstrip coupled line filters are popular for RF front ends, their large 2nd harmonic causes the shape of the pass band to be asymmetric in the upper band and it deteriorates the skirt properties. The 2nd harmonic can be completely suppressed using fractal geometry and making the skirt properties symmetric. It is achieved by varying the aspect ratio of the fractal geometry and finding the aspect ratio for which the second harmonic is completely suppressed. The above technique is validated by applying it to three different substrates. The performance of the filter is evaluated using ADS. Results show that the proposed filter possesses good return loss and transmission response enabling their use in a variety of wireless communication applications.