User's Guide

PTP 250 User Guide Planning for connectorized units
phn-2182_003v004 (Oct 2011)
UNDER DEVELOPMENT
2-13
Calculating maximum power level for connectorized units
If a connectorized PTP 250 link is to be installed in a country that imposes an EIRP limit in
the 5.4 GHz or 5.8 GHz band, choose an external antenna and RF cable that will not cause
the PTP 250 to exceed the EIRP limit. To calculate the highest setting of Maximum Power
Level that will be permitted, use this formula:
Maximum Power Level (dBm) =
Allowed EIRP (dBm) – Antenna Gain (dBi) + Cable Loss (dB)
Where: Is:
Maximum Power
Level (dBm)
the highest permissible setting of the
Maximum Power Level attribute in the
Step 2: Wireless Configuration page,
Allowed EIRP
(dBm)
the EIRP limit allowed by the regulations,
Antenna Gain
(dBi)
the gain of the chosen antenna,
Cable Loss (dB) the loss of the RF cable connecting the
ODU to the antenna.
As PTP 250 does not support Maximum Power Level settings below 4 dBm, the maximum
antenna gain (allowing for cable loss) is limited as shown in Table 2-6, based
on this
formula:
Maximum Antenna Gain (dBi) – Cable Loss (dB) = Allowed EIRP (dBm) – 4
Table 2-6 Setting maximum power level to meet EIRP limits
Band Regulation Allowed
EIRP
Maximum (Antenna
Gain - Cable Loss)
Maximum Power
Level
5.4 GHz FCC,
Canada and
ETSI
30 dBm 26 dBi 4 dBm
5.8 GHz ETSI 36 dBm 32 dBi 4 dBm
Specify Antenna Gain and Cable Loss in the installation report. They must be entered
correctly in the Wireless Wizard, as they are used by the software to impose an automatic
constaint on Maximum Power Level. For more information, see Step 2: Wireless
configuration on page 6-16.