Use this calculator to
walk through all the factors that make up your Total Power Output.
The Total Power Output is the the total power being output from
your wireless system and is the sum of:
Radio Transmit Power
-Less - cables and connectors losses
Enter one parameter in each column (or leave
blank) depending on what you know and the calculator will supply
the appropriate conversions automatically. Up to 2 decimal places
may be entered as 0.xx or .xx.
Note: Connector loss is generally
small UNLESS you've got lots of 'em in which case you are probably
in trouble anyway, or your cable is VERY short. Just leave the line
blank if you are feeling lazy.
Loss of power over distance (assuming no FRESNEL
Effect and nothing in the way). This a very idealised calculation
and in practice everything interferes with the signal but it will
give you a reasonable approximation of the actual loss over distance.
Enter the system Frequency in MHz and the distance
in either Kilometers (Km) or Miles below and then click the
'Calculate' button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.
Defines how much clearance you need (yes you need
more than simple Line-of-Sight) and for longer links > 3 Km (2
miles) whether you may have a ground clearance problem from our
friendly planet. For more info on M. Fresnel and his theories go
Enter the Total link distance (in Miles or
Kilometers), if you do not enter an Obstacle distance (in
Miles or Kilometers) the calculator will use the mid-point for all
calculations (Note: assumes antennas at same height). Finally
enter the system Frequency in MHz and then click the 'Calculate'
button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.
The calculator will generate the radius of the 1st
Fresnel zone only (at the obstable point or the mid-point), the
60% (no obstacle) radius and the height of the earth curvature at
the mid-point of the Total link distance.
This calculator will give you one of three answers:
If you leave distance blank it will apply the defined
SAD factor (or default to 30%) to the Operating Margin and supply
the max. distance (in Km and Miles) at which the Margin operates.
If you enter the distance it will calculate the
Operating Margin and the SAD factor.
If you enter distance but leave RX or TX antenna
gain (or both) blank it will apply the chosen SAD factor (or default
it to 30% if none supplied) and generate the required antenna
power. If both are left blank it will calculate a symmetrical
To RESET any parameter above just set to BLANK
before clicking 'Calculate'
Notes: RX Sensitivity is ALWAYS expressed as
a negative dBm (- dBm) and is the lowest power of signal your radio
can handle. Its buried somewhere in your radio spec and will be
typically in the range of -80 to -110 dBm. Don't guess or 'fudge'
milliWatts to dBm (and
Power in milliWatts to dBm (and vice versa) . Enter
the 'Transmit Power' (A or G above) in milliWatts
OR the 'Power Ratio' in dBm and click the appropriate 'Calculate'
button. 1 Watt = 1000 milliWatts.