A new definition of characteristic impedance

It is shown how a novel de-embedding technique, appropriate for electromagnetic analyses, results in a new three-dimensional definition of characteristic impedance, the transverse electromagnetic TEM equivalent characteristic impedance. This new definition is appropriate and unique for all inhomogeneous, as well as homogeneous, media. Further, the resulting characteristic impedance is shown, for a specific microstrip geometry, to have a nonmonotonic dispersion in characteristic impedance. This same dispersion is seen in measurements and is not seen in any of the classical, two-dimensional definitions of impedance.<>