FREKANS DAĞITICI MALZEMEYLE KAPLANMIŞ CİSİMLERİN RADAR KESİT ALANININ ZAMANDA SONLU FARKLAR YÖNTEMİ İLE HESAPLANMASI

Abstract

A MATLAB-based software tool has been developed under the scope of this study to calculate the Radar Cross Section (RCS) of three-dimensional complex targets with random geometry using the Finite Difference Time Domain (FDTD) method. The software is named "RaPTo", derived by selecting letters from the full name "Radar Cross Section Prediction Tool". The developed software is capable of modeling both conductive targets and targets coated with isotropic and frequency-dispersive materials. RaPTo allows for graphical results and visual simulations, aiming to contribute to the literature by providing a software infrastructure for RCS analysis and, particularly, RCS reduction applications.

RaPTo models the target mesh structure, initially modeled using triangular surfaces with any computer-aided design (CAD) software and saved in the .stl file format, into three-dimensional cubic elements using a ray-tracing algorithm. Using cubic elements, the software can calculate both monostatic and bistatic RCS values for the given problem. Three different models representing the characteristics of frequency-dispersive materials (Debye, Lorentz, and Drude models) can be defined within the software. Additionally, the material properties of the target in the problem can be defined as entirely conductive, entirely frequency-dispersive material, or conductive with a desired thickness of frequency-dispersive material. The RCS is calculated using the operation frequency and spherical coordinates of the plane wave specified by the user.

To validate the results obtained by the RaPTo software, a canonical object (i.e., a conductive sphere) was initially used. Bistatic RCS data obtained by RaPTo for the sphere were compared with both analytical results and bistatic RCS results obtained using the time domain solver of the commercial software CST Studio. Subsequently, bistatic RCS results obtained by RaPTo for a sphere coated with frequency-dispersive material (Lorentz, Debye, and Drude models) were compared with those obtained using CST. Finally, studies on RCS reduction were conducted. In this context, the impact of coated frequency-dispersive material on RCS reduction was investigated on both canonical geometries such as cube, sphere, and plate, and complex geometries such as F-117 Nighthawk and F-16 Fighting Falcon. The influence of coating thickness and collision frequency of the material on RCS was analyzed, and the results are presented comparatively.