Сборник докладов республиканской научно-технической конференции значение информационно-коммуникационных

METHODS OF DIVERSITY OF MOBILE COMMUNICATION 
ANTENNAS MOUNTED ON A SINGLE MAST 
A.Abdukadirov
 
(PhD, Tashkent University of Information Technologies) 
The modern rapid development of mobile (cellular) communication systems, 
bringing many new conveniences in our life, at the same time requires 
implementation of many works on planning, organization and maintenance of 
cellular networks. Particularly, issues of mobile networks’ base stations (BS) 
installation (especially in urban regions) has an increasing relevance in connection 
with the growing number of BSs, hardening ecological and electromagnetic 
restrictions, complication of antenna and mast constructions, etc. Cellular operators 
install their BSs according to their frequency-terrain planning and respectively, 
install antenna and mast constructions that, as a rule, have similar constructions 
and diagrams. Growth of a subscriber base and consequently need to increase a 
number of BSs leads to installation of several antennas and masts of different 
mobile operators on the same buildings and constructions (Fig. 1). 
Fig.1. Appearance of the building with BS antennas in urban regions 
Installation of a large number of bulky antenna and mast constructions of 
mobile communication is not absolutely desirable in a number of the city regions 
having important architectural, tourist and historical values as they worsen the 
esthetic appearance of those places. In this regard there is a need to minimize 
damage from installation of antenna and mast constructions in representative 
regions of the cities. 
Panel antennas representing antenna grids of cross radiation from symmetric 
vibrators supplied with reflectors are generally used for creating mobile networks 
in cities. Vertical symmetric vibrators in one or two rows are placed in a panel. 
The panel antennas have mechanical or electrical control of a tilt of the main beam 
pattern to regulate cover zone. 
Minimizing cross-effect of such antennas will be one of the major factors in 
development of technology of mobile antennas joint installation on a single mast. 
First of all, such influence is possible through the induced resistance which 
changes input resistances of antennas that leads to a mismatch of an antenna-
feeder path of BS. The vibrators that are in near distance to each other are called as 

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“connected vibrators”. Interference of connected vibrators is similar to the 
interference of connected oscillating circuits with concentrated constants. The field 
created by a system of vibrators is a result of addition of the fields created by 
separate vibrators taking into account phases of this field, defined as a difference 
of the course of rays, and a phase difference of currents in radiators. In the specific 
case, when vibrators are identical, parallel and are powered equally, the induced 
resistance is called mutual resistance. It is the function of values of