Wireless Link Budget Calculator
Check whether a radio link has enough margin to work.
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Wireless Link Budget Calculator by TheCalcTools
How the Wireless Link Budget Calculator works
Enter the transmitter power, both antenna gains, other losses, distance, frequency and the receiver’s sensitivity.
Received power is transmit power plus gains minus losses and path loss.
The fade margin is how far received power exceeds the sensitivity.
The formula
Worked example
Using the default values shown in the calculator:
| Transmit power (dBm) | 23 |
|---|---|
| Transmit antenna gain (dBi) | 12 |
| Receive antenna gain (dBi) | 12 |
| Cable and other losses (dB) | 3 |
| Distance (km) | 5 |
| Frequency (MHz) | 5800 |
| Receiver sensitivity (dBm) | -85 |
- FSPL at 5 km and 5,800 MHz = 121.69 dB.
- Prx = 23 + 12 + 12 − 3 − 121.69 = -77.69 dBm.
- Against a sensitivity of −85 dBm the margin is 7.31 dB. Marginal: add more margin.
Result:
| Free-space path loss (dB) | 121.69 |
|---|---|
| Received power (dBm) | -77.69 |
| Fade margin (dB) | 7.31 |
| Verdict | Marginal: add more margin |
Frequently asked questions
How much fade margin do I need?
10–20 dB is a common planning figure for fixed links, to cover rain, multipath and equipment ageing. Critical links use more.
Does this account for Fresnel zone clearance?
No. You must also keep the first Fresnel zone mostly clear of obstacles; this calculator only covers the power budget.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.