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Dynon Avionics SkyView System Installation Guide User Manual

Page 267

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SV-ADSB-470 Installation, Configuration, and Testing

SkyView System Installation Guide – Revision S

14-7

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 smallest practical ground plane is a square around 130 mm per side; as the
size increases the performance may actually get worse, but will be better by the time the
ground plane is 780 mm on each side. Anything much larger than that size is unlikely to show
significant further improvement.

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

An acceptable cable:

Has less than 3.0 dB loss for the run length needed. For runs less than 17 feet, RG58
is acceptable.

Has a characteristic impedance of 50 Ohms

If running the antenna cable in a bundle with or in close proximity to the
transponder antenna cable:

o Has double braid screens or has a foil and braid screen. For runs less than 17

feet, RG400 is acceptable.

When routing the cable, ensure that you:

Route the cable away from sources of heat.

Route the cable away from potential interference sources such as ignition wiring, 400Hz
generators, fluorescent lighting and electric motors.

Keep the cable run as short as possible.

Avoid routing the cable round tight bends.

Avoid kinking the cable even temporarily during installation.

Secure the cable so that it cannot interfere with other systems.

Antenna BNC Connector

This section describes the technique for attaching the antenna cable to a BNC connector. A BNC
connector is not supplied with the SV-ADSB-470. The SV-ADSB-470 has a female BNC
connection. Therefore, you will need to source a male BNC connector that is compatible with
the antenna cable type that meets your aircraft’s needs.