User's Manual

ITCR Base Radio User's Guide
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5/8/2013 Do Not Distribute 7
PEP referenced to the 2.15 dBi gain of a dipole. The EIRP for this case is 49.15 dBm.
Also note that the maximum ERP on FCC/IC channels 196-200 at 220.975 to 221.000
MHz is 2 watts.
Common single element fixed station antennas typically exhibit 2.1 to 5 dBi (0 to 2.9
dBd) gain and being vertically polarized, are usually omnidirectional. Multi-element
antennas are designed to concentrate RF radiated power toward the horizon and
away from the sky and the earth and depending on the design criteria provide
azimuthal gain directivity that decreases ERP in the direction of other base stations
or increases ERP in a specific direction. They may also be used to make up for large
losses between transmitter and antenna. The isotropic gain of a commonly-used
two-element exposed dipole antenna is typically 7 to 8 dBi.
Once the allowable ERP is determined by applying all power restrictive rules from
above and the antenna gain is known, the transmitter peak envelope power output
feeding the transmission line is determined by subtracting the antenna gain in dBi
from the EIRP and adding the loss from the antenna feedline and connectors plus
the loss from any combiners, cavity filters or lightning arresters. If the net value is
greater than or equal to 48.75 dBm, then the 75W maximum power of the Base
transmitter can be used. If the value is less than 48.75 dBm, then the transmitter
output power should be reduced to the net value. Example for the 50W ERP case:
Antenna gain = 8 dBi, feedline and connector loss = 2 dB. Assuming no other losses,
the transmitter power output limit = 49.15-8+2 = 43.15 dBm PEP or 20.7 W PEP. In
this case, the Base RF output power should be adjusted to 20.7 W PEP or less.
If the calculated transmitter power limit is less than the minimum Base rated power
of 10W PEP = 40 dBm PEP, then an external RF attenuator would be inserted in the
feed line to increase the loss between transmitter to achieve compliance.
4. Setup and Configuration for the Base Radio
Set up physical connections with the following:
DC Power
Ethernet
RF output termination
The sections below identify each of the physical connections.