Dynon Avionics SkyView System Installation Guide - Manual (Page 299)

SV-COM-C25 Installation, Configuration, and Testing
SkyView System Installation Guide – Revision S 16-17
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Separation of COM antenna from another COM or NAV antenna: Recommended separation
between COM antenna(s), NAV antenna(s), and ELT antennas is 6 feet (72 inches). Minimum
required separation between antennas is 4 feet (48 inches). Ideally, install the primary COM
antenna on the lower fuselage, and install the secondary / standby COM antenna on the
upper fuselage.

The COM antenna(s) should not be installed in close proximity to SkyView displays,
modules, or servos to avoid RF interference.

Where practical, plan the antenna location to keep the cable lengths as short as possible
and avoid sharp bends in the cable to minimize the VSWR (voltage standing wave ratio).

Double-shielded coaxial cable is superior to single shield coax – more of the transmit power
will be coupled to the antenna, and less received signal will be lost.

Electrical connection to the antenna should be protected to avoid loss of efficiency as a
result of the presence of liquids or moisture. All antenna feeders shall be installed in such a
way that a minimum of RF energy is radiated inside the aircraft.
Antenna Ground Plane
When a conventional aircraft monopole antenna is used it relies on a ground plane for correct
behaviour. For ideal performance the ground plane should be very large compared to the
wavelength of the transmission, which is approx. 7.5 feet. In a metal skinned aircraft this is
usually easy to accomplish, but is more difficult in a composite or fabric skinned aircraft. In
these cases a metallic ground plane should be fabricated and fitted under the antenna.
As the ground plane is made smaller, the actual dimensions of the ground plane become more
critical, and small multiples of the wavelength should be avoided, as should circles. Rectangles
or squares are much less likely to create a critical dimension that resonates with the
transmissions. The thickness of the material used to construct the ground plane is not critical,
providing it is sufficiently conductive. A variety of proprietary mesh and grid solutions are
available. Heavyweight cooking foil meets the technical requirements, but obviously needs to
be properly supported.
Antenna Cable
When routing the cable, ensure that you:

Route the cable away from sources of heat.

Avoid routing antenna cables together.

Route the cable away from potential interference sources such as ignition wiring, 400Hz
generators, fluorescent lighting and electric motors.

Allow a minimum separation of 300 mm (12 inches) from an ADF antenna cable.

Keep the cable run as short as possible.

Avoid routing the cable around tight bends.

Avoid kinking the cable even temporarily during installation.

Secure the cable so that it cannot interfere with other systems.