Transient Field Calculations for an Electric Dipole in Homogeneous Conducting Media

Expressions are given for the electric and magnetic field components of a pulsed electric dipole immersed in an infinite homogeneous medium with a specified conductivity and dielectric constant. The waveforms of the field components are illustrated graphically for both step-function and rectangular current pulses. While the diffusion approximation is adequate for many purposes, the retention of the displacement currents in the analysis leads to a more convincing presentation. For example, causality is always satisfied and the expected impulse contributions are contained in the final formulas. The waveform calculations show that microsecond pulses preserve their essential features for propagation distances less than about 50 meters in moderately or poorly conducting geological materials.