Title :
Multilevel fast-multipole algorithm for scattering from conducting targets above or embedded in a lossy half space
Author :
Geng, Norbert ; Sullivan, Anders ; Carin, Lawrence
Author_Institution :
Inst. fur Hochstfrequenztech. und Elektronik, Karlsruhe Univ., Germany
fDate :
7/1/2000 12:00:00 AM
Abstract :
An extension of the multilevel fast multipole algorithm (MLFMA), originally developed for targets in free space, is presented for the electromagnetic scattering from arbitrarily shaped three-dimensional (3-D), electrically large, perfectly conducting targets above or embedded within a lossy half space. We have developed and implemented electric-field, magnetic-field, and combined-field integral equations for this purpose. The nearby terms in the MLFMA framework are evaluated by using the rigorous half-space dyadic Green´s function, computed via the method of complex images. Non-nearby (far) MLFMA interactions, handled efficiently within the multilevel clustering construct, employ an approximate dyadic Green´s function. This is expressed in terms of a direct-radiation term plus a single real image (representing the asymptotic far-field Green´s function), with the image amplitude characterized by the polarization-dependent Fresnel reflection coefficient. Examples are presented to validate the code through comparison with a rigorous method-of-moments (MoM) solution. Finally, results are presented for scattering from a model unexploded ordnance (UXO) embedded in soil and for a realistic 3-D vehicle over soil
Keywords :
Green´s function methods; absorbing media; electric field integral equations; electromagnetic wave scattering; magnetic field integral equations; method of moments; MLFMA; UXO; combined-field integral equations; conducting targets; direct-radiation; electric-field integral equations; electrically large perfectly conducting targets; electromagnetic scattering; half-space dyadic Green´s function; lossy half space; magnetic-field integral equations; method of complex images; method-of-moments; multilevel clustering; multilevel fast-multipole algorithm; nearby terms; polarization-dependent Fresnel reflection coefficient; real image; realistic 3-D vehicle; scattering; unexploded ordnance; Electromagnetic scattering; Finite difference methods; Fresnel reflection; Integral equations; MLFMA; Moment methods; Polarization; Soil; Time domain analysis; Vehicles;
Journal_Title :
Geoscience and Remote Sensing, IEEE Transactions on