Effect of climatic factors on energy loss of millimeter range electromagnetic wave in passing through a precipitation layer on the mirror antenna reflector

Abstract

Problem statement. Communication systems transition to the millimeter wavelength range, as well as known theoretical studies on higher electromagnetic energy losses in precipitation in this range compared with the centimeter range have necessitated a scientific justification of an antenna protection method against climatic factors. This makes the chosen research topic relevant. Objective. Analysis of the climatic factors effect on the electromagnetic energy losses in the precipitation layer on the reflector of the millimeter wave range mirror antenna. Results. It is shown that the estimation of electromagnetic energy losses in the precipitation layer on the metal reflector of the mirror antenna should be carried out with the use of the basic statements of meteorological electromagnetism, which unites the statements of electrodynamics and statistical meteorology. Thus, to estimate the electromagnetic energy losses in the precipitation layer on the metal reflector of the millimeter wavelength reflector antenna, the model of the flat multi-layer dielectric coating on the metal screen can be used, which allows to relate the reflection factor to the layer parameters: the electrical parameters of the precipitation (value of the relative permittivity and the tangent angle of dielectric losses) and the layer thickness. Analysis of the known methods of finding the electrical parameters of meteorological precipitation showed that, firstly, it is difficult to measure the imaginary component of the relative permittivity of rain, ice, and snow in the millimeter frequency range. Secondly, there is no approved calculation methodology for the electrical parameters of snow, and the known models depend on random factors - the specific density of snow at the time of measurement and the electrical parameters of the ice and water that make up the snow and their concentrations. Third, finding the electrical characteristics of any type of precipitation characteristic of a given location of the mirror antenna depends on the air temperature. To justify the thickness of precipitation layer on the antenna reflector, the following statistical data are also necessary: the intensity of rain in a given location with a given probability, the daily rate of snow layer and the thickness of ice, which can form in a given climatic region on the metal elements of the mirror structure, including the reflector. Obtained results of electromagnetic energy losses in precipitation layer for different cases of meteorological conditions for millimeter band and their comparison with data for centimeter wavelength range have shown that the greatest losses (from 12-13 dB to 92 dB) in millimeter wavelength range, especially at frequencies above 60 GHz are caused by snow precipitation. In the centimeter wavelength range the maximum losses (up to 10 dB) can be observed in rain.