Complex compensation of coupled line structures in inhomogeneous media

This paper presents a novel method for the compensation of unequal phase velocities of coupled line structures in inhomogeneous media. By means of a rigorous scattering parameter analysis, ideal values for compensating impedances, connected in series to one or several ports of the coupler, are found. It is shown that, by properly choosing the values of the impedancespsila real and imaginary part, perfect isolation can theoretically be obtained at any frequency. Simulation and measurements are compared to previously published results, demonstrating the advantage of this novel approach.