This report uses model simulations to consider two questions: first are magnetic field effects of induced currents flowing in the earth significant for near-earth satellite observations; second, what are the effects at satellite altitudes of lateral differences in the gross conductivity structure of the earth. For distant sources in the magnetosphere, magnetic fields from electric currents induced in a spherical earth may contribute from 30 to 40% of the external source field amplitude. For near-earth sources beneath the satellite, e.g. in the ionosphere, the external and internal fields tend to cancel, resulting in a much smaller total horizontal field than would be associated with sources above the satellite. On the other hand, when lateral differences in conductivity are associated with the contact between major geologic units in the lithosphere, local concentrations of induced current may generate unique magnetic field signatures at satellite altitudes. Although the absolute amplitude of the field components may be an order of magnitude smaller than for the case when the source is above the satellite, the magnetic field perturbation measured by the satellite as it crosses the geologic contact is significantly larger than relative terms for ionospheric sources.