Transmission Line Model of Field-to-wire Coupling with Shielded TWP/Twinax Cables with line Apertures

Abstract

A transmission line model is generalized to characterize the effect of electromagnetic plane wave coupling with shielded twisted wire pair (TWP)/twinax cables with apertures on their shield. The model is applied in order to predict the response of the shielded TWP/twinax cables by obtaining the induced common-mode (CM) and differential-mode (DM) currents due to external electromagnetic interference. Therefore, the field-to-wire coupling to the outer shield is solved by applying the transmission line model. After that, the transfer impedance and admittance of the shield with line apertures are used to model the coupling from the outer shield to the inner wires. It is shown that the shielded TWP has better performance than the twinax cable in reducing the external interference. The results are validated using the commercial software FEKO, where a good agreement is obtained.