User's Manual

InfiNet Wireless R5000 Technical User Manual

Grounding when using IDU-LA

Antenna must be placed on the mast on the level that is at least 1 meter lower

than a mast‘s top. In this case it is of big probability that the lightning strikes the

mast and not the antenna. The mast is to be grounded on the grounding contour

according to your local standards. When the lightning strikes the antenna, the

current goes through the coaxial cable which grounds ODU clamp with the mast

– the mast is grounded via the grounding contour. The direct lightning strike to

the STP service cable (ODU-IDU) is partially terminated on the grounded IDU

case. Partial termination means that the direct lightning strike will probably

destroy an STP cable. The service cable pickups from the electromagnetic

impulses are terminated on the IDU case by the winding shield, and further – on

the grounding contour.

The end of the STP service cable that is connected to IDU should be

assembled with a Shielded RJ-45 connector. The other end of the STP

service cable (connected to ODU) should be assembled with

unshielded (standard) RJ-45 connector.

The data & power wires pickups are terminated via IDU protection scheme

(discharger and additional air gap). ODU and IDU grounding contours are

connected with 100kOhm resistor, and that provides no static charge

accumulation on the ODU case if there are some problems with its connection to

the grounding contour.

Antenna pole, tower, ODU and lightning arrestor must be connected

to the first common grounding contour. Cable thickness must be not

less than 10AWG using corrosion-steady connectors. Grounding

contour development must be done by the skilled personnel.

A special attention should be paid if antenna used is not DC-shorted. In this case

additional lightning arrestor should be used between the antenna and ODU.

Suggested grounding diagram is shown on the picture below.