A Triaxial Coil Receiver for Study of Subsurface Electromagnetic Propogation

A triaxial set of underwater receiving coils was developed and tested by engineers at Johns Hopkins Applied Physics Laboratory. The receiving system was used jointly with an underwater calibrated horizontal electric dipole source in studies of subsurface-to-subsurface extremely low frequency electromagnetic propagation. Knowledge of the characteristics of underwater electromagnetic propagation is applicable to geophysical exploration and communications. This paper discusses the electromechanical design of the receiver and tethering system, addresses system sensitivity and-noise levels, and presents representative results of system performance.