Analysis of coupled transmission lines with power-law characteristic impedance

We present a frequency-domain method for analyzing multiple-coupled nonuniform lossless transmission lines with powerlaw characteristic impedance. The method of the solution is based on the modal decomposition method. Using the modal decomposition method the system of coupled partial differential equations are decomposed to a number of uncoupled ordinary wave equations, which are then solved in the frequency-domain. Finally, the fast Fourier transform algorithm is used to find the time-domain response