About The Depth Of Investigation Of Different D.C. Dipole-Dipole Arrays

The depth of investigation characteristic (DIC) functions of the most commonly used dipole arrays are presented in this paper as a function of the characteristic angle between the transmitter and the receiver dipoles. The depth of investigation for each of the arrays except the parallel dipole-dipole array has a specific value, which is independent on the characteristic angle. From the point of view of the depth of investigation obtained, the dipole-dipole arrays form two groups: (1) the axial-like and (2) the equatorial-like arrays. The widely used statement by Roy and Apparao (1971) that the parallel dipole array with the special angle ϑ* = 54°44′8′’ would have an infinitely large depth of investigation must be modified. After a small dification in the interpretation process it becomes unambiguous that this array oes not see deeper than most of other dipole-dipole arrays.