ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The predictions of electrodynamic similitude, relating scattering from scaled targets to scattering from full-size targets, have been treated completely and rigorously. The usual assumption is made that the targets are those whose conductivity, permittivity, and permeability do not change with frequency. A complete set of solutions is presented to the three general nonlinear modeling equations in six variables. For the first time, particular emphasis is given to the effects of differences between absolute, geometric, and complete scaling on the electromagnetic fields and on the radar cross section, and effects of approximations to complete scaling are analyzed. Conditions are obtained on properties of materials required for models made from these materials to accurately simulate systems. Absorption and energy balance are also treated, and the influence of finite conductivity on surface currents is shown. The claim that scaled-down models may be used to represent real targets is based on the linearity of Maxwell's equations. Therefore, the physics involved in nonlocality and nonlinearity, its relation to the Maxwell equations in macroscopic media, and its impact on physical scale modeling are first examined. The behavior of electromagnetic fields is also treated as a function of frequency. Upper bounds on the electric conductivity and limitations on the electric and magnetic polarizability of realistic materials can have profound implications for model measurments. All the energy density in the reflected wave may be lost at higher frequencies by incomplete scaling of even apparently nonabsorptive targets. Thus, the ratio of measured radar cross sections of geometrically scaled targets to those predicted for a completely scaled model eventually approaches zero.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.339848
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