Incremental Length Diffraction Coefficients for the Shadow Boundary of a General Cylinder
Abstract
Incremental length diffraction coefficients (ILDCs) are obtained for the shadow boundaries of perfectly electrically conducting (PEC) convex cylinders of general cross section. A two step procedure is used. First, the nonuniform (NU) currents in the vicinity of the shadow boundary are approximated using Fock functions. The product of the approximated currents and the free space Green's function is then integrate on a differential strip of the cylinder surface transverse to the shadow boundary to obtain the ILDCs. This integration is performed in closed form by employing quadratic polynomial approximations for the amplitude and unwrapped phase of the integrand. The current approximations are numerically verified for circular and parabolic cylinders. The integration procedure is numerically verified by demonstrating that it produces an accurate far field pattern for a circular cylinder. Finally, as an example, the scattered far field of a PEC sphere is obtained by adding the integral of the NU ILDCs of a circular cylinder along the shadow boundary of the sphere to the physical optics (PO) far field of the sphere. This correction to the PO field is shown to significantly improve upon the accuracy of the PO far field approximation to the total scattered far field of the sphere.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1997
- Accession Number
- ADA351573
Entities
People
- Robert A. Shore
- Thorkild B. Hansen
Organizations
- Rome Laboratory