Broadband Electromagnetic Scattering Characteristics Of Electrically Large Conducting Targets

More information of objects can be obtained from developing the wide-band radar and ultra wide-band radar. With the frequency increasing and the wavelength decreasing, the original objects become electrically large objects. So it is important to study the wide-band electromagnetic scattering characteristics of electrically large objects.An idea for analyzing the electromagnetic scattering characteristics of electrically large objects is transforming the solution of large problems into that of some little problems. The object can be divided into a number of small regions or the equation be partitioned into some sub-equations, then the surface current and RCS can be computed fast by iterations.The theory of the method of moments (MOM) is introduced firstly in the thesis, and some basic functions and testing functions are discussed, then how to compute the radar cross sections of two-dimensional conducting objects are also introduced. As analyzing the electromagnetic scattering characteristics of two-dimensional electrically large conducting objects, the object is divided into some small regions by using spatial decomposition technique (SDT), but still consider the coupling effect among all the regions, the surface current and RCS of the object can be computed with progressive iterative numerical method (PNM). Then the wide-band electromagnetic scattering characteristics of two-dimensional electrically large conducting objects are analyzed with the asymptotic waveform evaluation (AWE) technique. In the end, the impedance matrix of any three-dimensional conducting object can be portioned into sub-matrices by the projection iterative method (PIM), the surface current and RCS can be calculated with convergent iterations, the wide-band electromagnetic scattering characteristics of three-dimensional conducting objects are also analyzed with the asymptotic waveform evaluation technique.The system analysis is given in the wide-band electromagnetic scatteringcharacteristics of two-dimensional and three-dimensional electrically large conducting objects for the first time in this thesis. Two projects are presented, the projects have higher efficiency than traditional MOM in analyzing the electromagnetic scattering characteristics of two-dimensional electrically large conducting objects, and while objects are very large, their wide-band electromagnetic scattering characteristics are very difficult to be analyzed by single MOM, but the second project can solve this problem very well.The investigation is very useful not only in further studying the electromagnetic scattering characteristics of complicated large objects over the whole frequency band, but also in improving and designing the wide-band radar, ultra wide-band radar and new wide-band radar absorbing material.