User's Manual

Table Of Contents
33
Copyright © 2004-2012 by InfiNet Wireless
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