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Link Budget Calculators

Free-space loss, EIRP, and received-power tools on one working page.

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Free-Space Loss

Frequency (30 kHz to 110 GHz)

Unit

Distance (100 m to 50,000 km)

Unit

Free-space loss

0 dB

FSL = 20 log₁₀(4πdf / c)
Distance is in metres; frequency is in hertz.

EIRP

Amplifier power (0 to 1 MW)

Unit

Transmit antenna gain (0 to 100 dB)dB

Transmit coupling loss (0 to 10 dB)dB

EIRP

0 W

EIRP(W) = P_amp(W) x 10^{(G_t - L_t) / 10}
EIRP(dBW) = P_amp(dBW) + G_t - L_t

Received Power

Amplifier power (0 to 1 MW)

Unit

Frequency (30 kHz to 110 GHz)

Unit

Distance (100 m to 50,000 km)

Unit

Transmit antenna gain (0 to 100 dB)dB

Receive antenna gain (0 to 100 dB)dB

Transmit coupling loss (0 to 10 dB)dB

Receive coupling loss (0 to 10 dB)dB

Atmospheric losses (0 to 10 dB)dB

Power flux density

0 W/m²

Received power

0 W

Flux density = EIRP / (4πd²), with atmospheric loss applied.
P_r(dBW) = P(dBW) + G_t + G_r - L_t - L_r - L_a - FSL

Communications Fundamentals

You may be interested in reading more in Communications Fundamentals: Chapter 11 and Chapter 12.

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