Data-reduction method for simultaneous measurement of permittivity and permeability with a short-circuited transmission line

Based on nonlinear least-squares optimization techniques and interpolation techniques, a data-reduction method for determining the complex electromagnetic parameters of materials with a short-circuited transmission line is presented in this paper, which takes frequency as an independent variable in order to establish independent reflection equations for the determination. After only one frequency-sweeping measurement, reflection equations are constructed by interpolation techniques and solved by nonlinear least-squares optimization techniques. With the help of this method, the short-circuited transmission line method can simultaneously measure the complex permittivity and permeability on a single sample at a single position in the shorted line. The optimization procedure is enough robust to converge to the correct value because of its less dependence on an initial guess.