Numerical solution of the direct problem of scattering applying to cylinders with different cross-section shape
Radio engineering. Electronics. Telecommunication systems
Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
AbstractThe purpose for this research was to find the main regularities of direct scattering problem solutions applying to elongated objects. Since the analytical solution of direct scattering problem exists only for objects with simple geometry, the numerical methods are required for scattered field calculation. In this research, space-time samples of scattered field were calculated using finite differences time domain method (FDTD) because of its possibility to cover wide frequency ranges with a single simulation. Compared to other methods, FDTD is simple and can be performed by any personal computer, since it does not require great computational resources. In this research, the objects were considered as ideally conducting and elongated one and only parallel polarization, where an electric field vector is parallel to the cylinder axis, was studied. It allowed using 2D models and calculating only 3 of total 6 vector field components, which reduces the numerical solution. The analysis of the obtained results shows that the main diffraction lobe direction and the direction of the incident plane wave usually are the same. The growth of object electric radius causes the growth of side lobe number. It also causes narrowing of the main lobe as well as radar cross-section growth. Plane wave incidence on square and triangular cylinders raises the side lobe level in specified directions. If the plane wave incidence direction is normal to the triangular (or square) cylinder's side, the back reflection level is only 1-2 dB less than main lobe level. Otherwise, when the wave is incident on the edge of the object, the back reflection is nearly unnoticeable. These results may be used for geometry and electromagnetic parameters retrieval in the inverse problem solution which is common in ground penetrating radar and the similar applications.
Keywords:scattering, diffraction, space-time signal, FDTD method, numerical simulation, radar cross-section
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