Feeder; Lightning Arrester (Optional) - Huawei Airbridge BTS3612A-1900 Technical Manual

Technical Manual
Airbridge BTS3612A CDMA Base Station
There are polarized diversity and space diversity. In the present mobile communication
system, horizontal space diversity and polarized diversity are both supported. Space
diversity is effective when the distance between two antennae is over 10 wavelengths.
Polarized diversity facilitates antenna installation and saves space, therefore it is used
more and more extensively.
V. Antenna isolation
The receiving/transmitting antenna must be installed with sufficient isolation to
minimize the effect on the receiver. The isolation space is subject to the spuriousness
of the transmitter and the characteristics of the receiver.

4.2.2 Feeder

Normally, the standard 7/8 inch or 5/4 inch feeders are used to connect the antenna
and cabinet. In the site installation, 7/16 DIN connectors should be prepared based on
the actual length of feeders.
Three grounding cable clips for lightning protection should be applied at the tower top
(or building roof), feeder middle, and the end close to the cabinet-bottom. If the feeder
is excessively long, additional cable clips should be applied evenly in the middle.
Since 7/8 inch and 5/4 inch feeders should not be bent, the tower top (or building roof)
antenna and the feeder, cabinet and the feeder should be connected via jumpers. The
jumpers provided by Huawei are 1/2 inch, 3.5m long, and with 7/16DIN connectors.
The attenuation of the feeder often used is listed in Table 4-1.
Table 4-1 Attenuation (dB/100m) of the feeder (ambient temperature 20°C)
Frequency Band
450MHz
800MHz
1900MHz
Standard conditions: VSWR 1.0, ambient temperature 20°C (68°F).

4.2.3 Lightning Arrester (Optional)

When the BTS3612A works at the 1900MHz band, the lightning arrester is necessary,
but for other bands, it is not necessary.
The lightning arrester is used to prevent damage of lightning current to the antenna &
feeder system.
7/8 inch feeder
2.65dB
3.9dB
5.9dB
4-3
Chapter 4 Antenna & Feeder Subsystem
5/4 inch feeder
1.87dB
2.8dB
4.51dB
System Principle