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Calcimator

Link Budget Calculator

Calculate end-to-end RF link budget from transmitter to receiver, including EIRP, path loss, and link margin.

Inputs

dBm
dB
dBi
MHz
km
dBi
dB
dBm
dB

Results

EIRP

38 dBm

Received Power

-71.02 dBm

Link Margin

13.98 dB

Free Space Path Loss114.02 dB
Total Path Loss117.02 dB
Link Viable1
Total Antenna Gain20 dBi
Total System Losses7 dB
How to Use This Calculator
  1. Enter transmit power (dBm), cable/connector losses (dB), and transmit antenna gain (dBi).
  2. Set frequency (MHz) and distance for free-space path loss calculation.
  3. Enter receive antenna gain (dBi), receive cable loss (dB), and receiver sensitivity (dBm).
  4. Review EIRP, FSPL, total path loss, received power, and link margin.
  5. Link margin should exceed 10-20 dB to account for fading, rain, and interference.

How the result changes with Transmit Power

Transmit PowerEIRPReceived PowerLink Margin
-21-13 dBm-122.02 dBm-37.02 dB
1.59.5 dBm-99.52 dBm-14.52 dB
2937 dBm-72.02 dBm12.98 dB
5159 dBm-50.02 dBm34.98 dB

What each input means

Transmit Power
Transmitter output power in dBm (30 dBm = 1 watt)
Tx Cable/Connector Loss
Total loss from transmitter to antenna (cables + connectors)
Tx Antenna Gain
Transmit antenna gain in dBi
Frequency
Operating frequency in megahertz
Distance
Distance between transmitter and receiver in kilometers
Rx Antenna Gain
Receive antenna gain in dBi
Rx Cable/Connector Loss
Total loss from antenna to receiver (cables + connectors)
Receiver Sensitivity
Minimum receivable signal level for reliable link
Additional Losses (Fade/Rain)
Extra margin for rain fade, atmospheric absorption, multipath, etc.

How this is calculated

Formula

Rx Power = Tx Power - Tx Loss + Tx Gain - FSPL - Addl Loss + Rx Gain - Rx Loss

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Transmit Power = 30, Tx Cable/Connector Loss = 2, Tx Antenna Gain = 10, Frequency = 2400 = 9 input(s) provided
  2. Calculate EIRP
    EIRP
    38 = 38
  3. Calculate Received Power
    Received Power
    -71.02 = -71.02
  4. Calculate Link Margin
    Link Margin
    13.98 = 13.98
  5. Calculate Free Space Path Loss
    Free Space Path Loss
    114.02 = 114.02
  6. Calculate Total Path Loss
    Total Path Loss
    117.02 = 117.02

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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