Fiziksel Optik Yöntemiyle Üç Boyutlu Cisimlerin Radar Kesit Alanının Hesaplanması

Abstract

Within the scope of the thesis, a MATLAB-based program has been developed which calculates the Radar Cross Section (RCS) of three dimensional complex targets with random geometry using the Physical Optics method. The currents induced on the target due to radar signals were calculated with the Physical Optics approach, and the scattered fields were obtained by solving the radiation integrals with highly oscillating integrand by employing the Ludwig method. The developed program can model both conductive targets and targets with a single or multilayer dielectric coating.

This developed program has the ability to calculate both monostatic and bistatic RCS by using the target mesh structure modeled using triangular facets and stored in an STL file generated by any Computer Aided Design (CAD) software. The polarization of the incident plane can be selected as horizontal or vertical, and the RCS results can be displayed in both co- and cross-polarizations expressed in 4 different polarization combinations as HH (Horizontal-Horizontal), HV (Horizontal-Vertical), VH (Vertical-Horizontal) and VV (Vertical-Vertical). The amplitudes of the complex surface current that is induced by the impact of the radar signal on the target geometry are displayed in different colors depending on their intensity. Dielectric materials defined in the programs’s own library, which can also be enhanced by the user by adding new materials, can be selected and applied to the target geometry with the desired thickness. What needs to be done is to define relative permittivity and permeability as well as dielectric and magnetic tangent loss of the material to be applied in the desired frequency of operation. Mainly, three different material types are considered: (i) Perfect Electric Conductor (PEC), (ii) multiple dielectric layers, and (ii) multiple dielectric layers coated on PEC. These material definitions can be done on either the entire mesh geometry or the selected triangular facets on the target.

The developed program was validated by comparing its results with some reference results generated by using the codes written for the RCS calculation of simple canonical geometries such as rectangular plate and sphere, as well as by using the software POFACETS and the commercial software FEKO. For complex geometries such as aircraft, helicopter and missile, the results were compared with the data obtained from FEKO. The developed software can be used in different practical applications such as the performance analysis of radar systems and the analysis of operational effectiveness of radar absorbant materials.

Keywords: RCS, mesh, Delaunay triangulation, three dimensional complex target, Physical Optics, Ludwig method, numerical integration, highly oscillatory functions, radar absorbant material, multiple layer dielelectric coating, MATLAB.