User guide

SATELLINE-3AS NMS / NMS Epic / NMS 869 / VHF

User Guide, Version 1.0

14.3.4 General antenna installation instructions

The reliability and the achievable coverage of useful signal strength can be severely affected by

the positioning of the antenna. Antenna and cable connectors should have gold-plated pins

and sockets, abuse of low quality connectors can lead to eventual oxidation of the connector

surfaces which in turn may degrade the contact and cause additional attenuation. Good quality

tools and materials must be used when installing radio modems, antennas and cables. The

weather tolerance of the materials used must also be taken into account. Installed materials

must withstand all foreseeable weather conditions (frost, excess sun, direct UV-radiation,

seawater etc.). Also possible environmental pollution must be considered (acids, ozone etc.).

Antennas must be installed well away from metallic objects. In the case of small antennas this

distance should be at least  m. With large antennas the distance should be >5 m and in case

of repeater antenna combinations >10 m.

If the system contains a large number of radio modems, the best location for an antenna is the

highest point of a building and possibly an additional antenna mast. If a separate antenna

mast is used, the antenna can, if necessary, be installed sideways about 2…3 m from the mast

itself.

When installing an antenna possible interference sources must be considered. Such interference

sources are, for example:

mobile telephone network base station antennas

public telephone network base station antennas

television broadcast antennas

radio relay antennas

other radio modem systems

PC-related devices (approximately 5 m radius from antenna)

When ordering antennas we request you to note that antennas are always tuned to a specific

frequency range. Simple antennas and antennas, which have been constructed of stacked yagi-

antennas, are typically rather broadband. As the number of yagi-elements increases the

frequency range becomes narrower.

When designing and installing a system it is advisable to prepare to test the system, and also to

consider serviceability of the system. In particular cabling should be planned to allow easy

access and to allow for maintenance. It is often practical to use long antenna cables, so that the

radio modem can be installed far enough from the antenna itself to a location that is easily

accessible.