Abstract :
The U.S. Navy has proposed a submarine communications system that operates at extremely low frequencies (ELF). The land-based transmitting antenna for this system consists of insulated conductors 50 to 100 km long, grounded at each end, and driven by a generator such that the flow of current would be along the cable, into the ground, deep in the earth, and return to the other grounded end of the cable. It would, in effect, be a large loop antenna in which the earth was part of the loop. Over the last ten years the Navy has sponsored a wide variety of research to evaluate the environmental impact of this system. A discussion of this work can logically fall into three periods: 1968 to 1973, 1973 to 1977, and work still in progress. The work during the first period was reviewed by an Ad Hoc Committee formed in 1973 by the Navy. A second committee was formed in 1976 by the National Academy of Sciences and charged to review all existing data. These committees have reported their findings but they are not readily available in the open literature. This paper does not duplicate the work of these committees but rather summarizes their results and combines them with more recent work some of which is still in progress.
