On the Effective Transfer Impedance of Thin Coaxial Cable Shields

It is shown that the effective transfer impedance per unit length of a thin coaxial cable shield is given by Zs h2/Ys, where ZS and Ys are, respectively, the cable's inductive transfer impedance per unit length and capacitive transfer admittance per unit length, and h is the axial propagation constant. This general result is illustrated by consideration of a specific shield model, the M-filar filamentary helix.