SV-ADSB-472 ADS-B IN Receiver Installation and Configuration
14-8 SkyView HDX System Installation Manual - Revision E
The following considerations should be considered when siting the antenna:
• The antenna should be well removed from any projections, the engine(s) and
propeller(s). It should also be well removed from landing gear doors, access
doors or other openings which will break the ground plane for the antenna.
• The antenna should be mounted on the bottom surface of the aircraft and in a
vertical position when the aircraft is in level flight.
• 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).
• The SV-ADSB-472 antenna should not be installed within two (2) feet (60.96
cm) of a 1090 MHz transponder (including the SV-XPNDR-261) antenna.
14.3.1 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 reception, which is 12.01 inches (305 mm). In a metal
skinned aircraft this is usually easy to accomplish, but is more difficult in a composite or
fabric skinned aircraft. In such 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 about 5.12 inches
(13.0 cm) per side; as the size increases the performance may actually get worse, but will
be better by the time the ground plane is 30.71 inches (78.0 cm) 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.
14.3.2 Antenna Cable
An acceptable cable:
• Has less than 3.0 dB loss for the run length needed. For runs less than 17 feet
(5.18 m), RG58 is acceptable.
• Has a characteristic impedance of 50 Ω (50 Ohms).
• If running the antenna cable in a bundle with or in close proximity to the SV-
XPNDR-261 antenna cable:
o Has double braid screens or has a foil and braid screen. For runs less than
17 feet (5.18 m), RG400 is acceptable.
When routing the cable, ensure that you:
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