Accurate, fast and stable solver for electromagnetic scattering of absorbing layer materials
DélyAlexandre
2016
<p>Poster presentation at the 2016 Defence and Security Doctoral Symposium.</p><p>The
boundary element method is an efficient and flexible tool for the modelling of
scattering of electromagnetic waves by conducting and penetrable objects. It
finds applications in the solution of forward and inverse problems in e.g.
radar footprint determination, stealth technology, and imaging for diagnostics
and security.</p>
<p>To model
scattering by objects that are for almost perfectly conducting, the classic
equations are augmented with a so called impedance boundary condition (IBC).
The IBC specifies a relationship between the electric field and the magnetic
field on the surface of the scatterer, or equivalently between the magnetic and
electric currents. IBC applications are numerous: especially they are well
suited to simulate metals coated by a dielectric/absorbing layer which is the
base of stealth technologies.</p>
<p>In this
contribution, an IBC enabled electric field integral equation will be
introduced that can provide accurate results in linear time complexity at
arbitrarily low frequency. The starting point of this work is the classic IBC
formulation. Unfortunately, this suffers from low frequency and dense grid
breakdowns. This means that the accuracy of the solution deteriorates and/or
the computation time increases, when the frequency is low and/or when the
number of unknown of the problem is high, because the iterative solvers used to
solve the linear system require more iterations.</p>
<p>The new IBC-EFIE introduced in
this work does not suffer from these problems and can deliver highly accurate
solutions at arbitrary frequency in near linear computational complexity. The formulation
is based on quasi Helmholtz decomposition techniques and multiplicative
preconditioners and yields a system whose condition number is independent of
both the frequency and the discretization density.</p><p><br></p>