Application of Gaussian Beam Summation Method in High-Frequency RCS of Complex Radar Targets
Résumé
Caustics problem is inherent to classical high
frequency approximation such Geometrical Optics (GO),
Geometric Theory of Diffraction (GTD), Uniform Theory of
Diffraction (UTD) and Equivalents Current Methods (MCE). All
these developments propose numerical estimations of the EM
field scattered from reflection, diffraction, and multiple
scattering from an object. In this paper we apply the Gaussian
beam summation technique (GBS) to simulate RCS of radar
target, especially for 5 to 10 wavelengths sizes. Gaussian beams
are asymptotic solutions of the Helmholtz equation within the
paraxial approximation. Since they are insensitive to ray
transition region, several techniques based on Gaussian beam are
used to evaluate high frequency EM wave equation, which
overcome partially or fully the difficulties of singular regions
(caustics, zero field in shadow zones). In this formulation, the
complete wave field at a receiver is evaluated as superposition of
Gaussian beams concentrated close to rays emerging from the
target, passing in a small neighborhood of the receiver. When the
incident field strikes the edges, the diffraction is accounted in a
complex weighing function, applying the geometrical theory of
diffraction (GTD). Simulation with canonical target shown will
be compared to asymptotic methods (Physical Optic) and
rigorous method (Method of moment)