An analysis of the magnetic field of a ring head with a highly permeable underlayer

摘要

An idealized mathematical model of the magnetic field due to a ring head with a highly permeable underlayer is solved using Fourier analysis. Accurate Fourier coefficients are derived for a range of gap dimensions. The leading term of the resulting exact series is shown to be equivalent to a previously published approximation, but it is demonstrated that this term alone is not normally sufficient to predict the field accurately.