A transparent free-space link-budget calculation for early RF planning and trade studies.

Local calculation: values are processed in your browser and are not transmitted. Optional profiles are stored only in this browser.

UAS profile Active profile: Manual values

Frequency *

MHz

Path distance *

Transmitter output power *

dBm

Transmit antenna gain *

dBi

Transmit-side losses *

Receive antenna gain *

dBi

Receive-side losses *

Additional path/system losses *

Receiver sensitivity *

dBm

Required fade margin *

Planning output only. Verify assumptions and results against authoritative data, manufacturer information, approved procedures, test evidence and competent engineering or regulatory review before use.

Calculation basis

Free-space path loss uses FSPL(dB) = 32.44 + 20log10(distance km) + 20log10(frequency MHz). Received power adds transmit power and antenna gains, then subtracts cable/system losses and FSPL. Raw link margin is received power minus receiver sensitivity; operational margin then subtracts the required fade margin.

Limitations and verification

Free-space loss does not include terrain, clutter, multipath, Fresnel obstruction, antenna orientation, polarisation mismatch, interference or atmospheric effects.
Receiver sensitivity is modulation, bandwidth, data-rate and error-rate dependent.
Check applicable spectrum, licensing and EIRP limits before transmission.

Version and review status

Formula set: v1.2
Staging review date: 17 August 2026
Status: Staging beta pending user acceptance and cross-browser checks.

RF Link Budget Calculator