Two-Octave Stopband Microstrip Low-Pass Filter Design using Butterfly Stubs

The application of a new design technique using non commensurate elements combined with the use of the butterfly stub permits lowpass filters with exceptional performances to be realised in microstrip configuration. Very compact microstrip filters exhibiting very high cutoff rates, two octave stopband widths, and stopband attenuations of 40 dB have been designed, fabricated and measured.