6.2.2    Frequency dependent wave impedance

QuickWave allows for calculations of the actual frequency dependent complex wave impedance of transmission lines (in Extended Results mode). The wave impedance is calculated at each transmission line port. It is given as a magnitude and phase curves, which can be easily transformed into real and imaginary parts using the built in calculator functions.

Note that it is well known that a characteristic impedance of a waveguide is not uniquely definable and it is a subject of arbitrary normalisation (see ref. [44]). In QW-3D we normalize the characteristic impedance of a waveguide mode in such a way that it is equal to unity at the frequency at which the mode template has been calculated (Matching frequency). Note however that in the case of TEM lines for which the unique definition of impedance is possible, QW-3D indicates the actual impedance of the line.

Frequency dependent wave impedance is calculated when S-Parameters post-processing is active and its results are displayed in the Extended Results regime.

A discussion concerning the wave impedance in the exemplary waveguide to coaxial line transition is presented in User Guide 3D: Advanced S-parameter problems for waveguide-to-coax example.