An improved method for the wave propagation constant gamma estimation in broadband uniform millimeter-wave transmission line

A new method is derived for computing the wave propagation constant gamma o f a uniform transmission line. The new method is based on the properties of a similar and unitary matrix and allows us to minimize the errors due to c onnection repeatability. These matrices are obtained from the wave cascade matrices (computed from scattering parameter measurements) of two different length lines of identical but unknown characteristic impedance. The useful ness of the new method is demonstrated by assessing the dispersion of the d ielectric constant epsilon(eff) and the attenuation constant alpha of an ul tra-low-loss transmission line in the frequency range of 0.040-65 GHz. (C) 1999 John Wiley & Sons, Inc.