User Manual

Link Budget Example
Version 1.1 - 01/04/00 23
Link Budget Example
Putting everything together, you must satisfy the following equation to have a successful
link:
Formulas: System Gain + Antenna Gain
≥
Propagation Loss + Fade Margin
+ Cable Losses + Connector Losses
or
Fade Margin
≥
System Gain + Antenna Gain - Propagation Loss -
Cable Losses - Connector Losses
where:
System Gain = Tx Power - Rx Sensitivity
Antenna Gains = Tx Antenna Gain + Rx Antenna Gain
Cable Losses = Base Cable Losses + Remote Cable Losses
Connector Losses = Base System Connector Losses + Remote
System Connector Losses
Variables: Desired Fade Margin = 13dB
Tx Power = 15dBm
Rx Sensitivity = -78dBm
Tx Antenna Gain = 9dB
Rx Antenna Gain = 15 dB
Propagation Loss for
desired range of 1km =
Tx Cable Losses
(2m LMR400) = .44dB
Rx Cable Losses
(2m LMR 400) = .44dB
Tx Connector Losses = .5dB
Rx Connector Losses = .5dB
Variable
Calculations:
System Gain = 15dBm - -78dBm = 93dBm
Antenna Gains = 9dB + 15dB = 24dB
Cable Losses = .44dB + .44dB = .88dB
Connector Losses = .5dB + .5dB = 1dB
Fade Margin
Calculation:
Fade Margin = 93dB + 24dB - 100dB - .88dB - 1dB = 15.12dB
Analysis: We have achieved the goal of a Fade Margin
≥
13dB.
The values for cable
and connector
losses in this
example are only for
illustration. You will
need to work these
out for your specific
installations.
100 20 1〈〉log×
+
100dB
=