RF coils, helical resonators and voltage magnification by coherent spatial modes

Abstract

By modeling a wire-wound coil as an anisotropically conducting cylindrical boundary, one may start from Maxwell's equations and deduce the structure's resonant behavior. Not only can the propagation factor and characteristic impedance be determined for such a helically disposed surface waveguide, but also its resonances, "self-capacitance" (so-called), and its voltage magnification by standing waves. Further, the Tesla coil passes to a conventional lumped element inductor as the helix is electrically shortened.