Aspects of electromagnetic scattering.
Thesis DisciplineElectrical Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
An expression for the field scattered by a perfectly conducting wedge with a deformed apex is formulated as a finite matrix equation to illustrate the application of the current density replacement technique. This technique enables the scattering from any size of body to be determined to a given accuracy after the inversion of one finite matrix, provided that the shape of the body can be derived by inwardly deforming a finite part of a body from which the scattering is known explicitly. The size of only the deformed part of the body is limited by available computational facilities. The field scattered from truncated and rounded wedges is calculated. These results not only enable the effect of edge deformation to be studied, but are also used to evaluate the accuracy of the geometrical theory of diffraction and physical optics estimates of the diffracted field. Expressions for the field scattered by a perfectly conducting wedge in the presence of transversely polarized line sources are found. These results are used with an iterative current density replacement technique to formulate expressions for the field scattered by a truncated wedge, and thus derive a secondary edge diffraction coefficient for use with the geometrical theory of diffraction. This coefficient is applicable to perfectly conducting bodies with small or large separation between edges. The increased accuracy obtainable with this coefficient, and a modification to the physical optics representation of the current density on a body with edges, are discussed.