A comparison of the inductive-limit footprints of airborne electromagnetic configurations

An inductive-limit model has been used to determine footprint sizes for a variety of common airborne electromagnetic-survey geometries.The model accounts both for variations in the height and orientation of the electromagnetic transmitter, and for electromagnetic coupling between the induced current system and the receiver. Horizontal magnetic-dipole transmitters are shown to have a smaller footprint than vertical magnetic-dipole sources. We show that footprint sizes for the vertical coaxial and vertical coplanar geometries are essentially identical, provided the transmitter-receiver separation is much less than the transmitter height. The inductive-limit horizontal-component footprint for a fixed-wing horizontal-loop transmitter with a towed-bird receiver is shown to be two-thirds of that for the vertical component. © 2004 Society of Exploration Geophysicists. All rights reserved.