ADRF PSR-78-9533-UA, Manual

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5.2 Antenna Separation/Isolation
The separation between the donor and server antennas is necessary to prevent oscillation. Oscillation occurs
when the signal entering the system continually re-enters, 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 5-4 RF Repeater Oscillation
To prevent feedback, the donor and server antennas must be separated by an appropriate distance to provide
sufficient isolation. Isolation can be attained by separating antennas at 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.
REPEATER
PS R-7 8-9 53 3