Undervannsdeteksjon med aktiv EM : beregninger i forenklet miljø

Abstract

A new system for detection of underwater targets by use of electromagnetic waves is considered. Extremely low frequency electromagnetic waves can be transmitted between transmitter and receiver arrays. Any target moving into the volume between the antennas will alter the propagation, and can be detected at the receiver. The system can detect both metallic and dielectric objects, but with a lower signal to noise ratio than what is experienced by magnetic systems for detection of ferromagnetic objects. The objective of this report is to identify the best frequency of operation and indicate an applicable system configuration. Electromagnetic propagation in the underwater environment is addressed along with the interaction of electromagnetic waves with possible targets. Accurate results are obtained for a continuous range of object sizes and operating frequencies by utilizing an analytic approach.