ULF/ELF electromagnetic fields produced in sea water by linear current sources

This report is concerned with the possibility of using undersea cables to communicate with undersea receivers at frequencies in the ultra low and extremely low ranges. Because of the low data transmission rate at these frequencies, communication is here understood to mean the transfer of short messages of high information content. We start by deriving theoretical expressions for the electric and magnetic fields generated in conducting medium of infinite extent by linear current sources (i.e., straight insulated current-carrying cables) of finite and semi-finite length and of finite length with gaps of either finite or infinitesimal size.