Near-Field Radiation Calculation of Irregular Wiring Twisted-Wire Pairs Based on Mode Decomposition

A near-field radiation model for irregular wiring twisted-wire pairs (TWPs) is built in this paper. Currents on wires are decomposed into a common mode (CM) and several differential modes (DMs), where CM is the direct contribution to radiation. By virtue of the electric/magnetic equivalent radius proposed here, CM quantities can be modeled as an irregular single wire above ground; DM quantities can be modeled as two-conductor transmission lines. Coupling between them due to termination imbalance is interpreted by equivalent circuits. Both the network matrix solution and the approximate solution are provided. The proposed model is validated by an exact solution of the method of moments and measurements.