IRIDIUM
ANTENNA
INSTALLATION
&
USER
MANUAL
5
2. Cabling
Using an externally mounted antenna provides an ideal solution for many applications. If you
have or plan to install an external antenna, it is very important that the cables used meet the
Iridium guidelines established for proper performance.
For optimal performance, we recommend using the shortest length of cable and the fewest
number of connectors possible.
3. RF Interference
All wireless devices, including satellite telephones, are susceptible to RF (radio frequency)
interference from other electronic devices. This problem is more evident when numerous
antennas and broadcasting devices are located within close proximity to each other.
The location of the INMARSAT antenna in relation to the Iridium antenna plays a significant role in
determining the degree of signal degradation that an Iridium subscriber can expect to experience.
Given the inherent system differences (LEO versus GEO), all Iridium units are susceptible to this
interference, regardless of the type of antenna being used.
Generally speaking, an Iridium unit; either handset or fixed terminal with an external antenna,
located within 15 and 45 meters (50 to 150 feet, respectively) of an operating INMARSAT mini-M
or Standard-C terminal, will likely experience degraded performance.
Other sources of RF interference such as Globalstar units, radar devices and broadcast stations
can provide interference for Iridium units, but usually are not encountered as frequently as
INMARSAT terminals.
Symptoms of RF Interference
Symptoms of RF interference include:
erratic or no signal strength indication,
dropped calls or warbled or otherwise distorted voice.
These symptoms may be intermittent or persistent, depending largely on the interference source,
its distance, strength and frequency relative to the Iridium unit.
Mitigation of RF Interference
Degradation of service due to RF interference to the Iridium unit can be significantly improved by:
a)
Increasing the distance and moving the Iridium antenna off-axis from the source of the
interference (therefore: to the side or behind the INMARSAT antenna, above or below it),
b)
Using an external band pass filter and an external antenna.
