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  5. To the question of defining the field of the system of radiators raised over the earth surface

To the question of defining the field of the system of radiators raised over the earth surface

L. Kornienko
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Description: The subject of the study is the method of reflective interpretation to calculate the antenna field raised above a smooth earth surface. The calculated relationships of the known method are obtained on the assumption of the presence in the antenna of a phase center, which is chosen as the origin. In this case, it is sufficient to take into account only the amplitude DN of the antenna. In modern radio engineering systems, complex radiating systems are used in which this condition may not be fulfilled. The generalization of the method of reflective interpretation to cases where the antenna does not have a phase center or it does not coincide with the origin of the coordinate system chosen for calculating antenna characteristics in free space. Formulas for the field and antenna directivity patterns are obtained in which, in contrast to known ones, its phase response is taken into account, which allows us to introduce corrections into the phase relationships of the direct and reflected waves when calculating the interference factor. It is shown that the positions of the extremes of the interference factor depend not only on the height of the antenna and the argument of the reflection coefficient, but also on the phase difference of the fields emitted by the antenna in the directions to the target and the reflection point that arises from the nonsphericity of the wave front. The results of calculations of the directional patterns of a vertical two-element horizontally polarized antenna array with nonuniform amplitude-phase excitation are considered taking into account the influence of the earth's surface. It is shown in particular that the invariance property of the amplitude DN with respect to the choice of the origin of the local coordinate system in the antenna is retained only when its phase characteristic is taken into account. The results of the studies can be used to calculate the technical characteristics of radio systems with a raised antenna whose radiation field is the result of interference of the direct and reflected waves, and the field of the surface wave can be neglected. An example is the calculation of the detection zone of the radar meter range, as well as radio links with high-elevated transmit and receive antennas


Keywords: smooth Earth, reflective interpretation method, phase characteristic, amplitude diagram, interference factor, amplitude-phase distribution, phase center, origin, spherical front, elevation of the antenna

Reference:
 Korniienko, L.H. (2018), “Do vyznachennia polia systemy vyprominiuvachiv, pidniatykh nad zemnoiu poverkhneiu” [To the question of defining the field of the system of radiators raised over the earth surface], Information Processing Systems, Vol. 3(154), pp. 33-38. https://doi.org/10.30748/soi.2018.154.05.