Duo-i6515/6525/8030NM
User Manual V1.6
Advanced RF Technologies, Inc. Proprietary Document
Page 17 of 40
2.3.4
Antenna Separation/Isolation
Separation between antennas is necessary to prevent oscillation. Oscillation
occurs when the signal entering the system continually reenters, due to the
lack of separation between the donor and server antennas. In other words, the
signal is being fed back into the system. This creates a constant amplification
of the same signal. As a result, the noise level rises above the signal level.
To prevent feedback, the donor and server antennas must be separated by an
appropriate distance to provide sufficient isolation. Isolation is attained by
separating antennas a sufficient distance so that the output of one antenna does
not reach the input of the other. This distance is dependent on the gain of the
repeater.
A sufficient isolation value is 13 ~ 15 dB greater than the maximum gain of
the repeater. For example, since the Duo-i8030NM has a maximum gain of
80 dB, it requires an isolation of at least 93 ~ 95 dB.
Figure 9 - RF Repeater Oscillation
Server
