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The electromagnetic scattering from a vertical discontinuity with application to ice hazard detection : an operator expansion approach

Authors
Publisher
Memorial University of Newfoundland
Publication Date
Disciplines
  • Mathematics
  • Physics

Abstract

The long range detection of ice hazards such as multi-year ice, pressure ridges and icebergs will allow for more efficient planning of Arctic navigation routes and exploration in ice infested waters. An analysis of the electromagnetic scattering from a vertical discontinuity representing the transition from sea water or first-year ice to a multi- year ice sheet has been carried out. The analysis is based on a method of Space/Field decomposition where two Heaviside functions are used to decompose a three dimensional space into three regions each having different electrical properties. Maxwell's equations are used to derive a partial differential field equation for the complete space. Making use of a field decomposition, this differential equation may be decomposed into three field equations, one for each region, and a boundary equation. A spherical Green's function is taken as the fundamental solution and the spatial Fourier transform is used to simplify the equations to a single integral equation. Selecting a vertical electric dipole as the source field the solution for the vertical component of the surface field is obtained by writing this resultant integral equation in an operator form and expanding the inverse operator in a Neumann series. Using the Laplace transform and stationary phase integration this series solution may be summed to provide expressions for both the backscattered field and the field propagated past the boundary separating the two media. The solution for the propagated field agrees with that of both Bremmer and Wait. The technique differs from that of previous investigators in that it is possible to obtain an expression for the backscattered field and thereby the radar cross-section of the vertical discontinuity. The results of this analysis indicate that radar operating in the High Frequency range (3 - 30 MHz) should provide a significant improvement over present methods for the detection of this type of hazard.

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