DEFINITION OF THE CHARACTERISTIC IMPEDANCE

Currently available definitions of the characteristic impedance are am biguous and/or inaccurate. A general definition, based on the descript ion of discontinuities between adjacent waveguides, is given. This def inition is accurate and independent of the structure concerned. So it can be applied to the design of passive components in any type of tran smission lines. Using this definition, a given structure can be unique ly characterized, but the absolute value of the characteristic impedan ce has no sense any more. the design of a microstrip impedance transfo rmer using this new definition is presented. using the mode-matching m ethod prove the accuracy of the theory.