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
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
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