Remote Sensing of 3-D Conducting Objects in a Layered Medium Using Electromagnetic Surface Waves

Antennas that are located on or near the boundary between two electrically different media, such as air and earth, or seawater and rock, are used as prospective tools for remote sensing and geophysical exploration. As an example, this letter examines the electromagnetic (EM) response of a metallic object that is submerged in a conducting layer of seawater that is situated between an infinite half-space of air and a seabed of lower electrical conductivity. When the source and the object are at some distance away in the water, the primary EM propagation mode is on the interfaces because the surface waves are less attenuated than those following the direct or reflected propagation paths. The simulation tool that predicts the performances of the EM detection system uses the method-of-moments integral equation technique. The method is validated and applied to calculate the scattered fields from a submerged perfectly conducting cylinder. The numerical results are then compared with experimental data that are obtained by towing a steel cylinder through an impressed field that is produced by a horizontal electric source.