Partial capacitance calculation for shielded twisted pair cables

This brief presents a method for the calculation of the capacitance of shielded twisted pair cables. The method presented allows the adoption of a realistic geometry of the shield in the analysis and does not limit the analysis to nonpractical geometrical primitives. The analysis is based on the combination of partial capacitances obtained through two-conformal mappings and by making a simple assumption on part of the geometry combined with the use of potentials. Comparisons with measurements, simulations, and with an analytical model deriving the capacitance for the pair in a cylindrical shield demonstrate a high level of agreement.