Fields from a vertical magnetic dipole beneath a layered earth

Both the E and H fields from a vertical magnetic dipole placed in the third layer of a three-layer earth are derived. The results are applied to transmission beneath two Wyoming coal seams to see the effects of the overburden upon the voltage induced in a horizontal loop which is coplanar with the dipole. Beneath each seam, the effects of the overburden can be neglected when both the dipole and loop are at least one meter below the seam and when the operating frequency is less than 15 kHz.