V H F B I D I R E C T I O N A L A M P L I F I E R T E C H N I C A L M A N U A L
19
Lightning Protection
Although relatively rugged, lightning can damage the internal working mechanisms inside the BDA.
We recommend the installation of a lightning surge suppressor in the transmission line where it enters
the building prior to the BDA. The suppressor should be grounded to the building ground bus at the
transmission line entry point. Choose a suppressor that will handle the expected amount of input power
from the BDA to the donor antenna.
Antenna Installation
Buildings that are not designed or upgraded for antenna systems need special attention for antenna mounting,
equipment installation and cable runs. There are many variables involved in the design of a DAS system
(distributed antenna system).
There are structural requirements for the location of the outdoor antenna (Donor); masts, towers, building
structure for handling wind and ice loading.
-Protection of antennas and cables from building occupants and general human interaction.
- Installers/designers must be aware of general seating, foot traffic areas and different access points.
- All Antennas must be designed for the working frequency, and ensure they meet the exposure
requirements.
- The donor antenna and distribution antennas must have 12 dB + the Maximum gain of the amplifier of
isolation between them. Less isolation will cause the module to overload and oscillation will occur which may
result in damage to the amplification module.
- Antennas should be mounted following the manufacture’s guidelines for RF connection and be affixed to the
building at the location of the desired signal.
- All cables used in the DAS system shall be 50 Ohms and clamped properly to ensure the cables 50 Ohm
impedance characteristics. Improper clamps will change the impedance of the cable at that location thus
changing the efficiency of the system.
- Antenna placement through the DAS system is important to produce a balanced, distributed signal. The use
of correct decouplers, power dividers, and signal taps is important to promote a balanced system.
