Common- and Differential-Mode Conversion Induced by Asymmetry and Dielectric Coating in a Transmission Line System

The asymmetry/coating-induced mode conversion (ACIMC) effect in a transmission line system is discussed in this letter. This effect is proved only to be induced when asymmetry and coating exist simultaneously. The reason for ACIMC is that asymmetry and coating lead to the inconsistency of current division factors for electric and magnetic effects. Based on this idea, ACIMC is modeled by adding common-mode current-controlled voltage sources in differential circuits, and the results agree well with those obtained by the method of moments. Moreover, it is proved that balanced-state-matched terminal loads do not exist for a asymmetric and coated transmission line system, but approximate ones at low frequencies could still be found.