User's Manual

Advanced RF Technologies, Inc.
20
2.3.3 RF
Figure 2-6 RF ports
The RF connections are made via two 4.3-10 female connectors. The RF connector labeled “DONOR” must be
connected to the antenna pointing towards the base station. The DONOR port can receive both 700 and 800MHz
public safety signals. The RF connection labeled “SERVER” must be connected to the antenna facing the area to
be covered by the BDA. The repeater has a single SERVER port that supports both 700 and 800MHz public safety
signals.
The RF connections must be made using cables with an impedance of 50 ohms.
The separation between the 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.
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.
DONOR – 4.3-10 female which is used to connect the donor antenna (700MHz + 800MHz PS)
DONOR_CPL (30dB) – SMA female 30 dB coupling port which is used to monitor the amplified UL signal
SERVER_CPL (30dB) – SMA female 30 dB coupling port which is used to monitor the amplified DL signal
SERVER – 4.3-10 female which is used to connect the server antenna (700MHz + 800MHz PS)