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Link Budget Calculator

Friis Equation · RSSI · Fade Margin · System Gain

When to use: Use to verify an RF link is viable before installation. Accounts for transmit power, cable losses, antenna gains, free space path loss, and receiver sensitivity to calculate RSSI and fade margin. A fade margin ≥ 10 dB is recommended for reliable links. Use for DAS donor links, BDA design, point-to-point radios, and public safety coverage verification. Get FSPL from the Path Loss calculator.

Transmitter Side
e.g. 30 dBm = 1 W
dBm
dB
dBi
Path & Receiver Side
Use Path Loss calculator
dB
2–5 dB typical
dB
dBi
dB
e.g. -95 dBm
dBm
Fade Margin
42.0
dB
✓ Link Pass
Link Summary
EIRP (TX power + ant gain − cable)30.0 dBm
Received Signal Strength (RSSI)-53.0 dBm
Receiver Sensitivity-95 dBm
Fade Margin (RSSI − sensitivity)42.0 dB
System Gain (TX − sensitivity)125.0 dB
References
Friis: RSSI = EIRP − FSPL + Grx − Lcable
Fade margin ≥ 10 dB for reliable links
NFPA 1221 §9.6 – public safety signal levels
IFC 510 – in-building emergency radio coverage