Contents I. Introduction
The electrostatic analysis of wound components has been a fascinating research field since the beginning of last century when the study of the surge performance of transformers became an increasingly crucial issue for predicting the devices' frequency behavior [1], [2]. As soon as wideband transformers began appearing in telecommunication systems in the forties [3], [4], so followed papers devoted to the frequency characterization of these magnetic components [5] and, in particular, to the calculation of their self-capacitance [6]–[11]. The definition of a self-capacitance as a shunt lumped-element in the equivalent circuit of the wire-wound component is a very useful tool to justify and reproduce the first resonant frequency. However, the concept of self capacitance is well beyond any lumped-element circuit theory since it is an attempt to circumvent transmission line effects on wound-components when the current distribution begins to depart from its dc behavior [12], [13]. Recently, procedures for calculating the capacitance have been proposed for inductors [14], planar transformers [15], [16], magnetic components within SMPS [17], high-frequency transformers [18], [19] and power transformers [6], [7].
