Andrew Wireless Innovations Group RPT-MR703P User Manual
U
SER
´
S MANUAL FOR BAND SELECTIVE REPEATERS
MR
X
03P
User'sManual.doc
Id.-No.:154999
Page 30
22-Jan-01
5.1.3. Antenna Isolation
Before setting the parameters of the repeater, ensure that the antenna isolation is
measured and optimized. The Safety-Gain-Margin (SGM) between the antenna
isolation and the maximum gain of the repeater is specified to +15 dB for all RF-
repeaters, i.e. the gain has to be -15 dB less than the isolation value of the antennas.
For better antenna isolation, ICE (Interference Cancellation Equipment) has been
developed for channel selective repeaters in the GSM900/1800 networks as well as
for PCS1900. ICE is specified for a SGM of –5 dB. Following example will show the
significant difference of a repeater with ICE-option compared to a repeater without
ICE-option.
Assumed case of a poor antenna isolation:
Before setting the parameters of the repeater, ensure that the antenna isolation is
measured and optimized. The Safety-Gain-Margin (SGM) between the antenna
isolation and the maximum gain of the repeater is specified to +15 dB for all RF-
repeaters, i.e. the gain has to be -15 dB less than the isolation value of the antennas.
For better antenna isolation, ICE (Interference Cancellation Equipment) has been
developed for channel selective repeaters in the GSM900/1800 networks as well as
for PCS1900. ICE is specified for a SGM of –5 dB. Following example will show the
significant difference of a repeater with ICE-option compared to a repeater without
ICE-option.
Assumed case of a poor antenna isolation:
•
Repeater without ICE
Antenna isolation:
80 dB
SGM:
- 15 dB
-------------
Allowed max. gain:
65 dB
In this case, the antenna isolation should be improved. The operator has to enlarge
the distance between both antennas or has to shield each antenna from the other.
Sometimes, it is difficult to enlarge the distance or to shield the antenna to reach the
necessary value.
The next example clarifies how to solve the antenna isolation problem with an ICE-
repeater. The SGM between the antenna isolation and the maximum gain is specified
to -5 dB, i.e. the gain can be +5 dB more than the isolation value of the antennas.
Assumed case of the same poor antenna isolation as in the previous example:
•
Repeater with ICE-option
Antenna isolation:
80 dB
SGM with ICE-option:
+5 dB higher
----------------------
Allowed max. gain:
85 dB
For further details to ICE or antenna isolation, please refer to MIKOM “Application
Note for Antenna Isolation” or “ICE Datasheet”.