Accounting for Wire Coating in the Modeling of Field Coupling to Twisted-Wire Pairs

This letter investigates the coupling of a plane-wave field to a twisted-wire pair (TWP) running above ground, with the objective to handle the practical relevant case of dielectric coating surrounding the two wires in the TWP. Closed-form expressions of the equivalent modal sources accounting for field-to-wire coupling are derived, and used to predict the modal voltages/currents induced at the TWP terminations. To represent propagation of the induced interference along the twisted line, per unit length parameters numerically evaluated on the average TWP cross section are exploited. Full-wave numerical simulations carried out by the Method of Moments confirm the accuracy of the proposed prediction model.