Modelling of interconnects including coaxial cables and multiconductor lines

In recent years, electromagnetic compatibility (EMC) problems associated with high frequency and high speed interconnects are becoming of increasing concern. Coaxial cables are a popular form of interconnect. In this thesis, the crosstalk coupling between two parallel coaxial cables in free space and above a ground plane is investigated. The degree of coupling is usually formulated analytically in the frequency domain. In this thesis, a method for time domain simulation is proposed using the TLM technique. Results are compared with frequency domain solutions and experimental results. Also; the standard model has been improved by including the skin depth effect in the coaxial cable braid. The crosstalk between the two coaxial cables is observed through the induced voltages on the loads of the adjacent cable, which is deemed to be the usual measureable form of cable coupling. The equivalent circuit developed for the coupling path of two coaxial cables in free space takes account of the differential mode (DM) current travelling in the braids of the cables. As for the coupling path of the cables via a ground plane, the equivalent circuit is developed based on the flow of differential mode (DM) and common mode (CM) currents in the braid, where the coaxial braid’s transfer impedance is modelled using Kley’s model. The radiated electric (E) field from the coaxial cable above a ground plane is also deduced from the predicted cable sheath current distribution and by the Hertzian dipoles’ approach. Results are validated against the radiated electric field of a single copper wire above ground. Both the simulated and experimental results are presented in the time and frequency domains and good agreement is observed thus validating the accuracy of the model