INTENSITY OF REFLECTED SIGNAL VOLTAGE FLUCTUATIONS AT SMALL IRREGULARITIES OF THE REFLECTING SEA SURFACE

Abstract

The work is devoted to the study of reflections of electromagnetic fields from images corresponding
to the limitations of the Kirchhoff method. An analysis of wave work known in the field of
diffraction allows us to conclude that solutions to problems of diffraction of wave characteristics
by uneven surfaces are reduced to one degree or another when deriving simplifying hypotheses.
Among the main simplifications are: limitation of radiation areas and, as a theory, fixation of
multipliers of integrated expressions, refusal to take into account the variability of local indicators
of the Fresnel reflection coefficient, solution of a single-position problem of wave diffraction in
conditions of combining points and reception, isotropic nature of the spatial structure of the reflecting
surface. The work solves the problem of estimating the range of voltage fluctuations of a
radar signal reflecting a small-scale rough sea surface, without accepting the main simplifying
hypotheses. Based on the general solution for the scattering fields of the main polarizations obtained
within the Kirchhoff method, analytical solutions for the intensity of fluctuations of the
complex amplitude of the field and the power of the incoherent component of the reflected signal
are analyzed. The relations obtained for the case of small heights of surface irregularities show
their differences from the known results. Functional dependences of the intensity of fluctuations of
the complex amplitude of the field and the power of the incoherent component on the electrical
parameters of the reflecting surface, on the magnitude of the spatial separation of the transmitting
and receiving antennas, on the wavelength and length of sea wave crests, on the width of the antenna
radiation pattern (APP) and on the magnitude of the surface inclinations were obtained.
Spatial separation of the transmitting and receiving antennas reduces the amount of power of the
incoherent component. The effect of diversity weakens as the beam expands and the flight altitude
increases. As the length of sea waves and the length of sea wave crests increase, the degree of
their influence on the power of the incoherent component weakens. It also weakens as the width of
the bottom expands and with a decrease in the radio wavelength. It is shown that in the decameter
range of radio waves, taking into account the slopes of the surface leads to a change in the intensity
of fluctuations of the reflected signal by a few percent only at sea wavelengths approaching the
radio wave length.