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For example, pilots of airplanes
(or helicopters) depend substantially on guidance systems that check
the alignment and the position of the airplane (or helicopter) during
landing especially at nights or poor visibility conditions. Consequently,
in order to ensure safety, the communications instrumentation should
be extremely reliable. However, when many antennas are placed on
the same structure (e.g., helicopter or airplane airframe) the problem
of interference and coupling between transmitting and/or receiving
elements can influence the operation and integrity of the communication
systems. |
Interference can corrupt
the signals with noise and deteriorate the quality of the communications.
In addition, it can cause jamming of the systems, followed by complete
interruption of already established communications. |
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respective owners. |
As the telecommunication systems
become more complex and more antennas are placed on the same structure
(e.g., helicopter airframe) the problem of interference becomes
significant for the performance of the systems. In helicopter communication
systems wire antennas, e.g., monopoles, whip elements, transmission
line antennas, etc., are used to provide HF, VHF and UHF links.
Also, other types of antennas, such as cavity-backed slot antennas
and patch antennas are used in the UHF or higher bands. Furthermore,
in specific applications very advanced communication systems are
required (e.g., communication systems of helicopters or aircraft).
