TY - CHAP

T1 - Electromagnetic scattering from a buried three-dimensional inhomogeneity in a lossy ground

AU - Kristensson, Gerhard

PY - 1979

Y1 - 1979

N2 - The T matrix method (also called the "extended boundary condi tion method" or "null field approach") introduced by Waterman, has recently been generalized to interfaces of infinite extent (G. Kristensson and S. Strom, J. Acoust. Soc. Am. 64917936 (1978) and G. Kristensson, Electromagnetic Scattering from Buried Inhomogeneities - a General Three Dimensional Formalism", Rep. 78-42, Inst. of Theoretical Physics, Göteborg (1978), to appear in J. Appl. Phys.). This paper extends the formalism to lossy materials. Here we explicitly assume that the ground and the inhomogeneity have losses, but the formalism also applies to a lossy medium above the ground with only minor changes. In developing the theory, we assumethe source to be situated above the ground but it is otherwise arbitrary. A similar formalism can be constructed when the source position is located in the ground or in the inhomogeneity. The scattered field is calculated both above and below the ground. Above the ground the scattered field separates into two parts, which have direct physical Interpretation, one field, here called the directly scattered field, which is the total scattered field when no buried obstacle is present, and a second field, the anomalous field, which reflects the presence of the inhomogeneity. We present some numerical computations of the field both above and below the ground for a flat earth and a buried perfectly conduction spheroid. The main theoretical developments are given in an appendix, where we study the transformation between plane and spherical vector waves for a complex wave number.

AB - The T matrix method (also called the "extended boundary condi tion method" or "null field approach") introduced by Waterman, has recently been generalized to interfaces of infinite extent (G. Kristensson and S. Strom, J. Acoust. Soc. Am. 64917936 (1978) and G. Kristensson, Electromagnetic Scattering from Buried Inhomogeneities - a General Three Dimensional Formalism", Rep. 78-42, Inst. of Theoretical Physics, Göteborg (1978), to appear in J. Appl. Phys.). This paper extends the formalism to lossy materials. Here we explicitly assume that the ground and the inhomogeneity have losses, but the formalism also applies to a lossy medium above the ground with only minor changes. In developing the theory, we assumethe source to be situated above the ground but it is otherwise arbitrary. A similar formalism can be constructed when the source position is located in the ground or in the inhomogeneity. The scattered field is calculated both above and below the ground. Above the ground the scattered field separates into two parts, which have direct physical Interpretation, one field, here called the directly scattered field, which is the total scattered field when no buried obstacle is present, and a second field, the anomalous field, which reflects the presence of the inhomogeneity. We present some numerical computations of the field both above and below the ground for a flat earth and a buried perfectly conduction spheroid. The main theoretical developments are given in an appendix, where we study the transformation between plane and spherical vector waves for a complex wave number.

M3 - Chapter in Report

T3 - Technical Report, Institute of Theoterical Physics, Chalmers University of Technology

BT - Technical Report

ER -