Bandpass Filters Using Parallel Coupled Strip-Line Stepped Impedance Resonators

Design formulae for bandpass filters using parallel coupled strip-line stepped impedance resonators (S.I.R.) are derived. The formulae take into account the arbitary coupling length as well as quarter-wavelength coupling. One of the important advantages of this filter is its ability to control spurious response by changing the structure of the resonator. Using the design formulae an experimental bandpass filter was designed and fabricated and its performance closely matched design data.