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Polarization method for navigation object selection in ship radar systems

Korban Dmytro

Zeszyty Naukowe Politechniki Morskiej w Szczecinie

2023

nr 76 (148)

17--22

This paper substantiates the method of polarization selection of navigation objects located in the zone of atmospheric formations (i.e., precipitation of different intensity and phase state), based on polarization differences in the parameters of their echo signals in a partially polarized electromagnetic wave arriving at the input of the all-polarized antenna of the ship radar polarization complex (SRPC). The partially polarized wave is represented as consisting of two polarized streams with polarization degrees m1 and m2 corresponding to the echo signals of the navigation object and atmospheric formation. The property of the partially polarized electromagnetic wave reflected from a complex object (i.e., navigation object located in the zone of atmospheric formation) is represented by real energy polarization Stokes parameters having intensity dimension. The scattering ability of the complex object is represented by the Mueller scattering matrix, the elements of which are measured by SRPC when it is sequentially irradiated with electromagnetic waves of four fixed polarizations. Polarization selection of navigation objects located in the zone of atmospheric formations uses the difference of polarization degrees of echo signals of the navigation object and atmospheric formation. The process of selection of the navigation object echo signal from the echo signal of the complex object and its observation on the screen of the SRPC indicator or computer display is based on the relationship between the degree of polarization of the electromagnetic wave and the polarization parameters of the navigation object echo signal and the atmospheric formation. The aim of this research is to develop polarization criteria of optimality of radar parameters of echo signals of partially polarized electromagnetic waves, represented by polarization degrees m1 and m2 corresponding to the navigational object and atmospheric formation observed by SRPC. As a result of the performed research, the problem of polarization selection of navigation objects located in the zone of atmospheric formations along the ship’s trajectory according to the values of the polarization degree of the navigation object echo signal is solved.

Changes in the states of polarization of random electromagnetic beams in atmospheric turbulence

Li J., Zhao K., Lai Y.

Optica Applicata

2017

Vol. 47, nr 1

51--62

Taking the random electromagnetic cosh-Gaussian beam as a typical example of random electromagnetic beams, the analytical expressions for the cross-spectral density matrix element of random electromagnetic cosh-Gaussian beams propagating through non-Kolmogorov atmospheric turbulence are derived, and used to study the changes in the states of polarization (degree of polarization, orientation angle and degree of ellipticity) of random electromagnetic cosh-Gaussian beams in non-Kolmogorov atmospheric turbulence. It is shown that the states of polarization of random electromagnetic cosh-Gaussian beams in non-Kolmogorov atmospheric turbulence are different from those in free space. The degree of polarization decreases, and the orientation angle and degree of ellipticity increase with increasing structure constant. The on-axis degree of polarization and the degree of ellipticity appear to have an oscillatory behavior and the orientation angle has a rapid transition for the larger cosh-part parameter of random electromagnetic cosh-Gaussian beams in atmospheric turbulence.