Computational and experimental method for measuring the frequency dependence of phase velocities of in-phase and antiphase waves in coupled lines with unbalanced electromagnetic coupling

A computational and experimental method for measuring the frequency dependence of the phase velocities of in-phase and antiphase waves in coupled strip transmission lines is described. The method is based on the experimental determination of the resonant frequencies of a section in which the first strip is current-carrying, is switched on between the input and output, and the second strip connected to the current-carrying strip is under a floating potential. With non-homogeneous dielectric filling, periodically repeated resonances are observed in the section. In parallel with experimental measurements, the frequency characteristics are calculated according to approximately defined primary parameters. At each of the resonant frequencies, the value of the calculated resonant frequency is reduced to the value of an experimentally determined frequency by varying the primary parameters. Then, according to the found primary parameters, the frequency dependences of the phase velocities of in-phase and in-phase waves in a complex form are determined. The method has been successfully applied to connected strip lines in the frequency range up to 8 GHz