Speaker: Professor Matthys Botha, Department of Electrical and Electronic Engineering, University of Stellenbosch, South Africa
Title: Fast physical optics for large-scale electromagnetic scattering analysis
Abstract: The asymptotic, physical optics (PO) approximation is applicable to electromagnetic scattering analysis of electrically large, conducting objects. Such analysis is important for various applications, including radar cross-section (RCS) calculations. Here, the induced surface current distribution, which is the solution variable, is represented in terms of conventional method-of-moments (MoM) basis functions upon a mesh of triangle elements.
The PO approximation yields the induced surface current distribution directly in terms of the incident magnetic field, taking line-of-sight visibility into account. This represents a single reflection. Multiple internal reflections can be solved for by successively regarding the PO currents as sources for further reflections. Internal reflections occur in case of concave scatterers. The main computational bottlenecks in such a multiple-reflection solution procedure are (i) to determine the visibility status of all basis functions relative to the incident field; and (ii) to determine the visibility status of all basis functions relative to each other; and (iii) to repeatedly calculate the field radiated by the current distribution.
This presentation starts by briefly reviewing relevant engineering electromagnetics concepts. The conventional single-reflection PO (SRPO) formulation is then presented, together with the acceleration of its incident field visibility determination (bottleneck task (i)), through an adaptive field-of-view buffer. The conventional multiple-reflection PO (MRPO) formulation is then presented, followed by methods to accelerate bottleneck tasks (ii) and (iii), yielding the fast MRPO (FMRPO) formulation. Internal reflected field calculations are accelerated with the multi-level fast multipole method (MLFMM). Internal shadowing is incorporated with a group-based approach, such that the beneficial cost-scaling property of the MLFMM is preserved. Numerical results are presented to demonstrate the efficiency of the FMRPO for general scattering objects.
EDIT room, floor 3, Hörsalsvägen 11, Campus Johanneberg
18 December, 2018, 11:00
18 December, 2018, 12:00