2-dimensional field analysis and input impedance of a finite-length solenoidal coil

The circumferential excitation-current sheet modelling a short coil immersed in an infinitely long circular-cylindrical multiregion structure is represented by a continuous spectrum of travelling waves; each energises an equivalent network that consists of a set of nonuniform transmission lines connected in cascade. The formulation in Bessel-function form is completely avoided by replacing each transmission line by a large number of T-circuits in cascade. The input `circuital impedance¿ of the solenoid is then related to the input `tensorial surface-wave impedance¿ of the equivalent network seen when looking from the excitation radius.