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In order to avoid interference, please note that the donor antenna should be far away from the
following objects.
Metal
High-voltage line
RF antenna
High-voltage transformer
Repeater is a two-way signal amplifier. So proper isolation between donor antenna and server
antenna is necessary in order to avoid self-oscillation. About the definition for self-oscillation,
take MIC and loudspeaker for example; if it is too close for each other, it could make big noise.
So the repeater can run smoothly if the isolation between donor antenna and server antenna is
15 dB higher than the gain of booster. For example, if the booster gain is 60 dB, then the
isolation between donor antenna and server antenna should be 75 decibel.
The minimum distance between donor antenna and server antenna is 10 meters, again the
direction of donor and server antennas shall be opposite.
As shown in the below illustration, the booster amplifies the signal R and signal T from the tower
at the same time. If the distance between donor antenna and server antenna is less than the
required distance, then the amplified signal R (T) will back to server antenna (donor antenna). So
it will lead to self-oscillation and reduce the coverage area, also the bad calling quality could
happen at the same time.
If isolation can’t be achieved by the limited distance, the roof of the building or other barriers can
be used to increase isolation.
