Symmetricom GPS Antenna, Installation Instructions Manual

Page: 11 / 32

GPS Antenna Sets
Description of the Parts
2. Description of the Parts
2.1. GPS Antenna
The supplied GPS antenna is an active antenna, especially designed for GPS timing
applications. The housing is specially constructed to withstand continuous, long-term
exposure to rugged or highly corrosive environments.
The antenna receives the satellites signals (GPS frequency: 1575.42 MHz) and passes it
trough a narrow band pass filter and a preamplifier. The GPS antenna will be supplied
with 5 V DC from the GPS receiver unit by the coaxial cable, witch also conducts the GPS
signal to the GPS receiver unit. The antenna is terminated with an “N” female connector.
2.2. Mounting Device
The kit for mast mounting consist of a 300 mm metal tube, one mounting fixture, two
clamps, four brackets and attaching parts. With the Symmetricom mounting device the
GPS antenna can be mounted on a mast with a diameter up to 60 mm or at a wall.
If wall mounting is applicable, the mounting fixture and the clamps can be used while
attaching parts are not included.
2.3. Antenna Cables and Connectors
For connection between antenna and GPS receiver unit (e.g. GPS LC) different coaxial-
cables are provided to be used. Dependent on the distance between GPS antenna and
GPS receiver unit different coaxial cables must be used. The difference of the cables are
cable diameter and insertion loss (see technical data). Each cable has an impedance of
50
Ω .
Because of the different cable diameter different N-type connectors must be used. At the
antenna only the straight N- type connector can be used and at the unit both, the straight
and the right-angle type of N- type connector can be used.
2.4. Lightning Protection
To protect the GPS receiver unit to be damaged by lightning strokes, a surge protector
should be installed. Surge protectors remove transient current that may induced onto the
inner conductor of coaxial cables.
To protect the GPS receiver unit, the surge protector should be installed as close as
possible to the GPS receiver unit. To proof a proper work of the surge protector it is very
important that the surge protector is grounded to a low impedance ground.
001023AD – July 2003
5