User Manual

Trilogue-1NM
User Manual V1.4
Advanced RF Technologies, Inc. Proprietary Document Page 17 of 43
2.3.4 Antenna Separation/Isolation
Separation between the 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.
Figure 9 – RF Repeater Oscillation
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, if the gain of the repeater is 50 dB, then an
isolation of 63 ~ 65 dB or greater is required. In the same manner, because
the Trilogue-1NM has a maximum gain of 80 dB, it requires an isolation of at
least 93 ~ 95 dB.
Server