A.N. Yakimov – Dr.Sc.(Eng.), Professor, Department of Designing and Technology of Electronic and Laser Means, Saint-Petersburg State University of Aerospace Instrumentation
E-mail: y_alder@mail.ru

A.R. Bestugin – Dr.Sc.(Eng.), Professor, Director of Institute of radio engineering, electronics and communication of Saint-Petersburg State University of Aerospace Instrumentation
E-mail: fresguap@mail.ru

I.A. Kirshina – Ph.D.(Econ.), Associate Professor, 
Saint-Petersburg State University of Aerospace Instrumentation
E-mail: zlata@aanet.ru

The problem of optimization of the microwave antenna of the land radio communication line using for information transfer electromagnetic waves, method of mathematical modeling is considered. It is shown that the following assumptions are necessary for creation of the mathematical model considering influence of parameters of the used antennas on characteristics of the land radio communication line: the land surface flat and ideally smooth, electromagnetic waves are monochromatic, are created and extend in the linear, homogeneous and isotropic environment with small conductivity in the absence of external sources of the field. 

     The received formulas allow to calculate coefficient of strengthening of the microwave antenna taking into account parameters of the directional pattern of the antenna: width of the main petal at the level of the half power and the maximum level of side petals. They can be used also for assessment of the impact of the external deforming impacts on a design of this antenna. At such influences the design of the microwave antenna gets difficult spatial configurations which mathematical modeling becomes a final and element method, possible as a result of discrete representation. Among a set of the methods used in numerical modeling of characteristics of antennas it was the most effective. 

     The problem of optimization of the microwave antenna of the land radio communication line with use of the power criterion providing achievement of the maximum range at the set level of side radiation is solved. An important element of optimization of the antenna is introduction of the necessary restrictions providing in the course of optimization of the antenna preservation of its parameters in the set limits. The given results of a model research of parameters of the microwave antenna of centimetric wave band used in the land radio communication line show that temperature change of the environment and overheating of a surface of the reflector of the real parabolic antenna sunlight significantly change its characteristics and it needs to be considered at design and operation of microwave antennas. 

     Use of the obtained data together with results of modeling of radio lines will allow to perform optimization of these radio lines on their maximum range taking into account the impact of external influences. The offered approach to mathematical modeling of microwave antennas and the land radio communication lines using these antennas allows to estimate negative results of thermal influences at a design stage that gives the chance to create optimum in the set service conditions of a design of antennas and adequately to estimate changes of their characteristics at such external influences.

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