**AN ENGINEERING MODEL FOR CALCULATING SIGNAL LEVELS FOR TRANS-HORIZON TROPOSPHERIC PROPAGATION OF VHF AND MICROWAVE RANGES TAKING INTO ACCOUNT THE ELEVATION HEIGHTS OF THE EMITTING AND RECEIVING ANTENNAS**

UDC 537.87

DOI:10.26102/2310-6018/2020.29.2.025

A.L. Khanis, S.V. Bespalko, V.A. Khanis, A.A. Khanis

*The relevance of the article is due to the practical needs of calculating signal levels for over-horizon tropospheric propagation of radio waves in the absence of detailed data on the state of the troposphere and the earth’s surface. Currently, there are a number of numerical computer models for calculating signal levels in conditions of over-the-horizon propagation of radio waves, taking into account the elevation of the transmitting and receiving antennas, but they require a large amount of initial information in the form of detailed meteorological observations, forecasts of the state of the atmosphere, as well as data on the terrain and the state of the Earth’s surface, which are usually unavailable. The existing approximate engineering models that do not require detailed data about the conditions of radio wave propagation are developed in relation to the location of the transmitting and receiving antennas on the Earth’s surface. The model proposed in this paper is based on the introduction of an average attenuation multiplier for standard conditions in the troposphere, transmitting and receiving antennas placed on flight-lifting vehicles and splitting the propagation route into sections of line of sight and over-horizon propagation. The purpose of the study is to develop and describe a model for calculating signal levels (attenuation multiplier) in the conditions of over-horizon tropospheric propagation of radio waves, in relation to the case of placement of radiating and receiving antennas on flight-lifting vehicles. The tasks that are solved to achieve this goal consist in analyzing the radio wave propagation path and estimating the attenuation factor on the route as a sum of factors that characterize losses on sections of the route of various types – line of sight, diffraction zone and far tropospheric propagation. The method for estimating the attenuation factor on the track is to use a well-known engineering method for standard conditions of long-range tropospheric propagation as the base model for calculating the coefficient. The result of this work is a mathematical expression for engineering calculation of signal levels for over-horizon tropospheric propagation of radio waves, taking into account the elevation of the radiating and receiving antennas. The proposed model is based on the introduction of an average attenuation multiplier for standard conditions in the troposphere, transmitting and receiving antennas placed on flight-lifting facilities and splitting the propagation route into sections of line of sight and over-horizon propagation.it can be used for approximate estimation of the received signal levels during over-horizon tropospheric propagation of radio waves without detailed data on the state of the troposphere and the Earth’s surface.
*

**Keywords:**radio wave attenuation factor, horizontal tropospheric propagation of radio waves, calculation of signal levels on the propagation paths of radio waves, transmitting antenna, receiving antenna, flight-lifting equipment, refraction, diffraction, line of sight

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