Review of the past Work in the Field

Methods for reducing Radar Cross Section (RCS) of objects have been investigated by many researchers both experimentally and theoretically for the last so many years. This chapter presents a chronological review of important research in the fields of RCS studies, RCS reduction techniques and fractal based scattering and radiating structures. This chapter is divided into two sections. The first section presents a review of Res studies, ReS reduction techniques and its measurement techniques and the studies offractal electrodynamics are reviewed in the second section. Review of the past work done in the field 23 2.1 RADAR CROSS SECTION STUDIES The history of investigations on Radar Cross Section dates back to the early part of twentieth century. The results of the investigations were not published until World War H. From the end of the World War II till the present time, the radar response of specific targets has continued to be an area of considerable interest to many researchers, and great deal of work has been reported in the field. The analysis and measurements on RC; of various objects are available in open literature [1-4]. Hu [5] had measured the RC; of a dipole antenna in the VHF range with the input terminals of the dipole shorted. The experimental results were compared with theoretical values. w. J. Bow et al [6] presented the computed radar cross section data for microstrip patch antenna arrays as a function of array size, incident signal frequency, and anisotropy. E. H Newman and Forria [7] presented a solution to the problem of plane wave scattering hy a rectangular microstrip patch on a grounded dielectric substrate. The model does not include the microstrip feed, and thus does not include the so-called "antenna mode" component of the scattering. The solution begins by formulating an electric field integral equation for the surface current density on the microstrip patch. D. Pozar [8] envisaged the problem of a rectangular microstrip antenna printed on a uniaxially anisotropic substrate. The effect of anisotropyon the resonant frequency and surface wave excitation of the antenna is considered, and the radar cross section (RC;) of the antenna is calculated. The RC; calculation includes the effect of the load impedance (antenna mode scattering). The derivation of the uniaxial Green's function 24 Chapter 2 in spectral form, the associated moment method analysis for the input impedance and scattering of the microstrip patch, and the expressions for the far-zone …