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System Performance Wireless Calculator

Evaluate wireless system performance with free-space loss, receive power, link margin, and a SAD (spare available down)-style factor versus the transmit budget. This standalone page is suited for SEO on operating margin, fade margin, and RF link analysis.

System Performance Wireless Calculator — How far will it go, will it get there or what is my Operating Margin?

This wireless calculator will give you one of three answers:

  1. 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.
  2. If you enter the distance it will calculate the Operating Margin and the SAD factor.
  3. 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 antenna gain.

To RESET any parameter just set it 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. RX Sensativity should be listed in your radio manual and will be typically in the range of -70 to -110 dBm.

Note: If you solve for TX antenna (you leave it blank) and define a specific SAD factor it is applied to the TX budget and any TX antenna value will include this factor. If you then click Calculate again without changing anything, the SAD factor will be calculated to include the supplied TX antenna value and thus may show a lower value than the original one.

This page implements the distance-known mode: enter frequency, distance, TX/RX chain, and sensitivity to obtain FS loss, received power, operating margin, theoretical margin, and SAD factor. For inverse solves (distance from margin, or antenna gain from SAD), use the original combined tool or extend this script in your CMS.

See the calculations and equations used for this wireless calculator.

FrequencyDistanceFS Loss
— dB
TX PowerTX CableTX AntennaTotal TX
or mW — dBm
RX SensitivityRX CableRX AntennaTotal RX
— dB (receive-side gains/losses)
MarginRX PowerSAD FactorTheoretical
— dB — dBm — % — dB

System Performance Calculations

  1. Free space loss = 32.45 + 20Log10(Frequency in MHz) + 20Log10(Distance in Km). Miles are converted to Km (× 1.609) before this formula.
  2. mW to dBm = 10Log10(mW)
  3. dBm to mW = 10(dBm/10)
  4. TX power budget (dBm) = TX power + TX antenna + TX cable (cable losses entered as negative dB)
  5. RX power budget (dB) = RX antenna + RX cable (receive-side gains/losses only; sensitivity is not included)
  6. Received power (dBm) = TX power budget + RX power budget − free space loss
  7. Operating margin (dB) = received power − RX sensitivity
  8. Theoretical margin = TX power budget + RX power budget − free space loss
  9. SAD factor = Theoretical margin / TX power budget × 100
Disclaimer: Due to the nature of radio frequency propagation and the numerous factors that can affect operating range we do not guarantee that you will achieve any specific range for your application. These wireless calculators are for estimation purposes only. L-com does not guarantee their accuracy or applicability. L-com cannot be held liable for wireless installations based on these tools. Customers should use these tools at their own risk. After you are finished on this page, please visit our line-up of wireless antennas.

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