System for underwater communications comprising fluid modifying means

摘要

The present invention provides a system for underwater communications by electromagnetic signals capable of providing a higher data transfer rate for a given range of communications than current prior art systems for underwater communications by electromagnetic signals. The system has an active mode of operation and an inactive mode. In the inactive mode the transmit antenna and the receive antenna are arranged so that the region extending between them is occupied by water. During the active mode, a fluid modifying means provides a reduced conductivity fluid in the region between the transmit antenna and the receive antenna and electromagnetic signals are transmitted from the transmitter to the receiver via the reduced conductivity fluid thereby providing a higher data transfer rate for a given range of communications.