User Guide

Table Of Contents
PMP 450 Planning Guide Link planning
pmp-0047 (December 2012)
2-17
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 AP to the
antenna.
For more information on EIRP limits, see Compliance with radio regulations on page 4-13.
.
Understanding Attenuation
An RF signal in space is attenuated by atmospheric and other effects as a function of the distance from the initial
transmission point. The further a reception point is placed from the transmission point, the weaker is the received
RF signal.
Calculating Link Loss
The link loss is the total attenuation of the wireless signal between two point-to-multipoint units. The link loss
calculation is presented below:
Link Loss (dB) = Transmit power of the remote wireless unit (dBm) Tx Cable loss (dB) Received power
at the local unit (dBm) Rx cable loss (dB) + Antenna gain at the remote unit (dBi) + Antenna gain at the
local unit (dBi)
Calculating Rx Signal Level
The Rx sensitivity of each module is provided at http://www.cambiumnetworks.com. The determinants in Rx signal
level are illustrated in Figure 11.
Figure 11 Determinants in Rx signal level
Rx signal level is calculated as follows: