The effects of near-field coupling between ELF antennas and power and telephone systems

With the advent of the Navy's proposed ELF Communications System (Sanguine System), which would use an earth-return circuit to excite the earth-ionosphere cavity, earth-return current coupling into telephone and also power systems has become important. The theoretical basis for the coupling into power distribution and telephone systems is developed. A comparison is made between measured and predicted values of the induced voltage. Techniques which are useful in eliminating the effects of the induced voltage are described. The effectiveness of these interference mitigation techniques is demonstrated by comparing measurements on actual systems.