User's Manual

5.4 HOW TO SHIELD ANTENNAS
Antennas may be shielded by a purpose built ferrite sheet only. In special circumstances devices such as
keyboards and computers may be placed under antennas where a purpose built ferrite antenna shield
(64-50-001) is provided to protect the antenna.
A ferrite shield consists of a sheet of aluminium with ferrite tiles, minimum thickness 5 mm.
Contact Magellan for further information on shielding antennas for your speci c applications and for the
speci cation of the Ferrite Antenna Shield (64-50-001) when planning your installation.
5.5 ANTENNA MAINTENANCE (TUNING)
Antennas may require periodic re-tuning and testing. Detuning of an antenna may occur if the physical
environment around the antenna is changed. This can occur, for example, when large metal objects are located
near the antenna or electronic devices or cables are placed in close proximity with the antenna. The severity of
detuning is dependent upon the size of the metal object and can only be determined by measurement.
Before tuning make sure that metal objects, electronic devices and cables are not closer that the recommended
distances in any direction from the antenna.
The purpose of the tuning procedure is to maintain an antenna at its correct operating point. Tuning the antenna
means to trim it to its highest possible  eld strength which corresponds to the highest voltage as measured by
a voltmeter with an Antenna Tuning Probe.
If in doubt, contact Magellan for further instructions for your speci c application.
07-Jul-07 63-70-006-DOC 33
MARS-24E
User Manual