Antennas in Dissipative Media and in Subsurface Communication.

摘要

Researches directed toward understanding and improving communication between antennas below the surface of the earth are reviewed. They have included: (1) The development of a new method for the in situ measurement of the electrical properties of a dissipative medium, (2) the selection of the insulated dipole as the most versatile for the purpose, (3) the theoretical and experimental determination of currents, charge, and admittances of rotationally symmetric and eccentrically insulated antennas in various media and of arrays of such elements, (4) the determination of the electromagnetic field of dipoles in sea and lake water and dry earth near the air interface by numerical methods. The need to extend the results to antennas of finite length including traveling-wave insulated antennas is pointed out. Reference is made to a new method for measuring the electric field in a medium in a manner independent of its electrical properties, (5) the properties of the receiving antenna are obtained with the reciprocal theorem or by direct analysis if quantities other than the voltage across the load are required, (6) the information still needed to answer the following question is summarized: With the most directive transmitting and receiving antenna that can be designed, under what conditions and over what distances is subsurface communication practical in the earth's crust. (Author)