COMMUNICATION ANTENNA EMITTING IN TRANSVERSE VERTICAL PLANE OF AIRCRAFT by ProQuest

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									                                                                                                  Science & Military 2/2009




                COMMUNICATION ANTENNA EMITTING IN TRANSVERSE
                        VERTICAL PLANE OF AIRCRAFT
                                    Ján LABUN, Pavol KURDEL, Pavol LIPOVSKÝ

Abstract: In professional and laymen circles there is a prevailing idea that in order to enlarge the boundary of the radio
communication range, it is appropriate to bank an aircraft so that to improve the line of sight of the antenna with reference to
the ground communication point. This theory is true on condition that the angle of banking does not exceed a certain stated
angle, which is specific for each type of aircraft and is dependent on various factors. It is about the factors such as dimensions
and the shape of the aircraft, location of the antenna on the aircraft surface, operating frequency etc. From this point of view,
the article is a treatise on the causes and rules underlying of the frequency drops in the radiation pattern of the communication
antenna located on the body of the aircraft from the point of the angle of bank with the minimum level of the signal received.
As it is generally known, the change in the level of signal reception is of substantial effect on the range of communication
link.

Keywords: Asymmetric dipole, aircraft antenna, range of radio communication.


1 INTRODUCTION                                                       and laws of the occurrence of outlet of direction
                                                                     diagram of communication antenna placed on the
    For air communication, the aircraft usually uses                 metal aircraft fuselage from the point of view of
the antenna of non-symmetrical dipole type –                         determining the bank angle with minimal level of
unipole, which is commonly fitted to the upper axis                  received signal.
part of aircraft fuselage. Given position of this
dipole has the task to ensure circular direction
                                                                     2 ANTENNA ON SPACIOUS CONDUCTIVE
diagram in horizontal plane and by this guarantee
                                                                       SURFACE
quality connection of the aircraft with control center
in any direction.
    From the point of view of securing certain –                         Necessary and objective requirement of placing
wider range of frequency band, the dipole has                        antenna of radio communication means on the
usually larger – wider dimensions. As the antenna                    surface of conductive metal aircraft fuselage
has to have also good aerodynamical features, this                   presents a situation of placing the antenna in the
antenna is then shaped (recently) into the shape of                  vicinity of spacious, well conductive surface. To
a fin. In spite of these conditions, the antenna has                 calculate the radiation of antennas placed within
to have required electric parameters and radiation                   spacious, well conductive surface, we use a well-
features available.                                                  known principle of reflection. The field of radiating
    In professional as well as amateur air community                 antenna induces currents, which also contribute to
there is a prevailing opinion that to increase the                   the total radiation of the antenna, in the conductive –
range of connection it is advantageous to bank the                   metal aircraft fuselage.
aircraft so that the antenna would be “better”                           The share of induced currents is equivalent to the
uncovered towards the ground communication point.                    radiation of reflection image of antenna according to
This theory is right, however, the bank angle should   
								
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