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 ElectroDynamic Systems Software ScientificTM Radiolocation Systems ResearchTM 
Antenna array Complex directional antenna consists of separate near-omnidirectional antennas (radiating elements) positioned in the space and driven by high-frequency … (from 'Glossary' of our web–site)  |
Archives for 20051/ 2/ 3/ 4/ 5/ all pages Wednesday, December 21, 2005 at 12:12AM
It is shown that the directivity factor of the antenna located in a lossy medium is limited and its maximum value is finite.
Tuesday, December 20, 2005 at 12:12AM
The formula that relates the integral diameter of the distance to the effective absorbing surface of the aperture receiving antenna is derived and using this formula, the conditions of minimizing the diameter and its value are found.
Monday, December 19, 2005 at 12:12AM
The method of solving problems of diffraction on non-Rayleight bodies, composed of several Rayleigh bodies is explained. The scattered field is constructed as a sum of fields, created by the assemblage of multifields, each of them is located in the corresponding point of one of the composite bodies. The samples involving two tangent to the generatrix of the cylinder and two touching in the single point spheres are considered. For the former of these samples, the curves of distribution current density and scatterogram are given. The curves are compared with the corresponding curves, derived using the Kirhgoff approximation.
Sunday, December 18, 2005 at 12:12AM
The problem of diffraction of electromagnetic waves on a curvilinear surfaces with piecewise continuous admittance (impedance) boundary conditions, particularly on open-ended metallic surfaces is considered. It is shown that the coefficients of Fourier kind for some complete function system and the corresponding series for the function equal to the tangent component of the electric vector on the part of the surface where the admittance is finite and the surface electric current on the part where it is infinite, can be found by solving the inner and exterior boundary value problem. Each of the terms of the series satisfies the Meixner condition and the determined values of the tangent field on the given surface allow determining of the scattered field in the whole space. The method is illustrated with a sample of diffraction of a plane wave on a circular cylinder with the admittance periodically alternating in steps along the axis.
Saturday, December 17, 2005 at 12:12AM
The article expresses the conditions that must be met when measuring the radio-locating cross-section of a target in terms of amplitude and incident field phase variation. A number of minimal distance criteria are examined. The analysis of minimal distance for the cases when the antenna has a uniformly lighted square aperture is given, and the relation that binds the minimal distance to the sensitivity of measurements. The measurements of the reflection properties of small targets in near zones of focused and unfocused apertures are described. It is shown that the “minimal distance” can be substantially lowered using the suitable microwave lens when measuring the reflection properties of medium and large-sized targets.
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