Impedance Measurements of Nonuniform Transmission Lines in Time Domain Using an Improved Recursive Multiple Reflection Computation Method

In this paper, a recursive computation method is developed to derive the multiple reflections of nonuniform transmission lines. The true impedance profiles of the nonuniform transmission lines are then reconstructed with the help of this method. This method is more efficient than other algorithm. To validate this method, two nonuniform microstrip lines are designed and measured using Agilent vector network analyzer E8363B from 10MHz to 20 GHz with 10MHz interval. The reflection coefficients of these nonuniform microstrip lines in time domain are attained from the scattering parameters using inverse Chirp-Z transform. The reconstructed characteristic impedance profiles of the nonuniform lines are compared with those reconstructed by Izydorczyk’s algorithm. The agreements of the results illustrate the validity of the recursive multiple reflection computation method in this paper.