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 power-law 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.