Kodlanmış Metamalzeme ile Radar Soğurucu Malzeme Tasarımı

Abstract

The importance of the RADAR systems that detect, identify and track an object/target is increasing day by day in military and civilian fields. One of the most important parameters of RADAR system performance is RADAR cross sectional (RCS) area of an object/target. Especially in military fields, RADAR cross section reduction techniques are applied to reduce the detection, identification and trackability of the target. One of the RADAR cross section reduction techniques is the use of RADAR absorbing materials. On the other hand, RADAR absorbing materials are also used for electromagnetic measurements and to improve antenna parameters. Within the scope of this thesis, information about RADAR absorbing material design with coding metamaterials, which is a new method in RADAR absorbing material design, based on the manipulation of the electromagnetic wave with different phase responses, was given. Firstly, general information about RADAR and RADAR cross section, RADAR absorbing structures and metamaterials, coding metamaterials were given. After that, the far field scattering formulas were derived, and particle swarm optimization algorithm was implemented in MATLAB environment. Unit cell designs that have wide frequency range, polarization independent, angularly stable and 2 different phase responses have been obtained. The coding metamaterials were designed with obtained unit cells and optimization algorithms. The designed coding metamaterial that cover C – X – Ku frequency bands, RADAR cross section values were compared with MATLAB and CST full-wave simulation results and shared. The coding metamaterial was fabricated; so that, the measurement and simulation results were compared. With the designed coding metamaterial, at normal incidence angle, horizontal and vertical polarization independent, at least 7 dB mono-static RADAR cross section reduction was achieved in between 5.2 and 15.8 GHz and bi-static RADAR cross section reduction was achieved in between 5.4 and 15.6 GHz. In addition, the case of oblique incidence electromagnetic wave was investigated and RADAR cross section reduction up to 45° was achieved with narrowing the bandwidth slightly.