Ўзбекистон республикаси ахборот технологиялари ва коммуникацияларини ривожлантириш вазирлиги муҳаммад ал-хоразмий номидаги



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туплам 21(06.04)

l/λ

d/λ
and 
h/λ

i.e. they are defined by exclusively geometrical system size. (Here 
l
- length of a 
vibrator shoulder, 
d
- distance between vibrators of the antenna, 
h
- spacing 
between the panel antennas and 
λ
- wavelength). 
The active and reactive components of mutual resistance depending on the 
relative distance 
d/λ
between vibrators are accepted both the positive, and the 
negative values and in case of some 
d/λ
values pass through zero. Similar 
dependence is noticed in case of change of 
h/λ
. Respectively, the active component 
of the induced resistance can be positive or negative. 
Radio signal propagation and, therefore, value of the induced resistance is 
influenced by the restriction placed between antennas. Therefore, it is possible to 
assume that the restriction-shield placed between panel antennas of mobile 
network allows reducing vertical distance between antennas without 
communication quality deterioration. There is a matter of the restriction-shield 
shape. Indeed the restriction in the shape of, say, cutting-edge will not reduce but 
increase the cross impact of antennas. Therefore, a smoothly changing shape of a 
restriction-shield was selected for further research, so as wave’s diffraction on it 
will have considerable loose as, for example, on a shield in the shape of a sphere, 
cylinder or an ellipsoid of rotation. 
An experimental installation has been created for these purposes. The 
transmitting part consisted of the microwave generator G4-83 connected to funnel-
shaped antenna by coaxial cable and coaxial-to-waveguide transition. 
The receiving part consisted of the funnel-shaped antenna connected to 
Agilent E4407B spectrum analyzer through waveguide-to-coax transition and the 
coaxial cable, as well. The restriction-shield was placed between the receiver and 
transmitter. Frequency of the generator was selected equal to 10GHz (
λ
= 3 sm), 
and simulation coefficient - equal to 11 that corresponded to operating frequency 
range of GSM standard – 900MHz. 
Block diagram of the installation to weakening an electromagnetic field on 
restrictions of different shape is given in fig.2. 
Experiments discovered that the power level on the receiver input decreases 
in case of installation of restriction-shield in the shape of a sphere or cylinder in 
average by twenty and more dB, i.e. 100 times and more. Therefore, the 
restriction-shield in the shape of a sphere or cylinder gives an increase in 
decoupling between antennas more than 100 times. 
A great interest for us represents also an influence of value of the relative 
spacing of 
h/λ
between an antenna and a restriction as well as between two 


116 
antennas on value of the induced resistance, i.e. on value of the standing wave ratio 
(SWR) in the panel antenna feeder. 
Fig.2. Block diagram of the experimental installation on research of weakening a field on 
restriction (1 – G4-83 microwave generator, 2 – coaxial cable, 3 – transmitting funnel-shaped 
antenna, 4 – restriction-shield, 5 - receiving funnel-shaped antenna, 6 - spectrum analyzer) 
A mobile panel antenna, restriction-shield made full-scale of the metal lath 
with cells of 35 mm and a spectrum analyzer FSH-6 have been used for this 
experiment. The spectrum analyzer had built-in generator which was connected to 
the antenna, and dependence of SWR values on frequency was displayed on the 
analyzer display. 
Block diagram of the experimental installation on restriction-shield 
influence on the SWR value in the feeder of transmitting panel antenna is shown in 
fig. 3. 
Fig.3. Block diagram of the experimental installation on research of restriction-shield influence 
on the SWR value in the feeder of transmitting panel antenna (1 – spectrum analyzer FSH-6, 2 – 
coaxial cable, 3 - antenna, 4 - restriction-shield) 
A distance between antenna and a restriction-shield changed during the 
experiment. It was discovered that existence of a restriction-shield brings an 
increase of the SWR value in the feeder from 1,20 to 1,21. In case of increasing the 
size of a restriction-shield from 40cm up to 75cm in diameter the SWR value 
increased only for 0,05. That is, the extremely feeble dependence of the antenna 
matching on value of 
h/λ
and the size of a restriction has been observed.
A diagram of such an installation option of different mobile operators 
antennas on one mast with use of a spherical shield is given in fig. 4. 
Fig.4. A diagram of different mobile operators antennas on one mast with use of a spherical 
restriction-shield (1 - panel antennas, 2 - a mast, 3 - feeder paths, 4 and 5 – BS transceivers, 6 – 
a building roof, 7 – a restriction-shield) 


117 
Also, one of the factors influencing on the value of antennas diversity is 
spatial selectivity of antennas. But, since mobile station antennas have a wide 
range of directivity, this factor can be neglected. 
Thus, using restriction-shields between different mobile operators’ panel 
antennas allows to considerably reducing the distance between antennas when 
installing them on one mast and it can decrease a concentration of antenna masts 
installation on roofs, especially in central representative areas of the cities. And 
this, in turn, will improve esthetic architectural image of our cities. 

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