Common-Mode Contribution to Currents Induced on a Terminated Multiconductor Transmission Line in a Reverberant Field

The currents induced on terminated multiconductor transmission lines (MTLs) by stochastic electromagnetic fields in overmoded cavities are examined numerically. Techniques that find the mean-squared currents from a rigorously defined number of deterministic evaluations are applied to classic transmission line and moment method models. The calculations show that line imbalance leads to significant common-mode contributions to the induced currents in approximately matched termination loads that are not predicted by transmission line theory. The relative level of the common-mode contribution is dependent on the level of line imbalance presented by the full MTL cross-section around the termination load under test. A reduction in cross-section dimensions leads to an increase in the relative contribution of the common mode.