Transmission Line Modeling and Crosstalk Analysis of Multibraided Shielded TWP/Twinax Cables

In this article, the transmission line model of multibraided shielded cables is improved by including the proximity effect in the shield model. This is performed by deriving the analytical expressions of the transfer impedance and admittance of a shielded structure with nonuniform current distribution around the shield surfaces. After that, the formulations are generalized to be applicable for shielded twisted-wire pair (TWP) and twinax cables with line apertures and braided structure with nonuniform shield current. It is found that the nonuniform distribution of the currents in the outer and inner shield surfaces have high effects on the inner induced common-mode and differential-mode currents of braided shielded cables. In addition, the crosstalk between multishielded TWP and twinax cables is investigated in detail, indicating that the proximity effects between the shields have a critical impact on generating the crosstalk between the shielded cables. The proposed model is validated with the commercial software FEKO and excellent agreements are achieved.