Accession Number : ADA137353

Title :   Numerical Solutions to Ill-Posed and Well-Posed Impedance Boundary Condition Integral Equations.

Descriptive Note : Technical rept.,

Corporate Author : MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB

Personal Author(s) : Rogers,J R

PDF Url : ADA137353

Report Date : 30 Nov 1983

Pagination or Media Count : 98

Abstract : Exterior scattering from a three-dimensional impedance body can be formulated in terms of various integral equations derived from the Leontovich impedance boundary condition (IBC). The electric and magnetic field integral equations are ill-posed because they theoretically admit spurious solutions at the frequencies of interior perfect conductor cavity resonances. A combined field formulation is well-posed because it does not allow the spurious solutions. This report outlines the derivation of IBC integral equations and describes a procedure for constructing moment-method solutions for bodies of revolution. Numerical results for scattering from impedance spheres are presented which contrast the stability and accuracy of solutions to the ill-posed equations with those of the well-posed equation. The results show that numerical solutions for exterior scattering to the electric and magnetic field integral equations can be severely contaminated by spurious resonant solutions regardless of whether the surface impedance of the body is lossy or lossless.

Descriptors :   *Integral equations, *Method of moments, *Solutions(General), *Electromagnetic scattering, *Bodies of revolution, Impedance, Three dimensional, Cavity resonators, Fortran, Computer programs, Numerical analysis, Surfaces, Algorithms

Subject Categories : Theoretical Mathematics
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE