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Calcimator

EIRP Calculator

Calculate Effective Isotropic Radiated Power from transmit power, cable loss, connector loss, and antenna gain.

Inputs

dBm
dB
dB
dBi

Results

EIRP

37.5 dBm

EIRP

5.623 W

EIRP7.5 dBW
Tx Power1 W
Power at Antenna Port27.5 dBm
Total System Loss2.5 dB
Over FCC 36 dBm Limit1.5 dB
How to Use This Calculator
  1. Enter transmit power (dBm) -- the calculator converts to watts automatically.
  2. Set cable loss (dB) and connector loss (dB) between the transmitter and antenna.
  3. Enter antenna gain (dBi).
  4. Review EIRP in dBm, dBW, and watts -- the effective radiated power in the direction of maximum gain.
  5. Verify EIRP complies with FCC Part 15, Part 97, or your applicable regulatory limit.

How the result changes with Transmit Power

Transmit PowerEIRPEIRP
-21-13.5 dBm0 W
1.59 dBm0.008 W
2936.5 dBm4.467 W
5158.5 dBm707.946 W

What each input means

Transmit Power
Radio transmitter output power in dBm (30 dBm = 1 watt)
Cable Loss
Total coaxial cable attenuation from radio to antenna
Connector Loss
Total loss from all connectors (typically 0.15-0.5 dB each)
Antenna Gain
Antenna gain referenced to isotropic radiator

How this is calculated

Formula

EIRP = Tx Power - Cable Loss - Connector Loss + Antenna Gain

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Transmit Power = 30, Cable Loss = 2, Connector Loss = 0.5, Antenna Gain = 10 = 4 input(s) provided
  2. Calculate EIRP
    EIRP
    37.5 = 37.5
  3. Calculate EIRP
    EIRP
    5.623 = 5.623
  4. Calculate EIRP
    EIRP
    7.5 = 7.5
  5. Calculate Tx Power
    Tx Power
    1 = 1

Engine last updated . Checked against 4 independently-derived tests — how we verify calculators.

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