Friis Transmission Equation Calculator

Enter your Transmitter Power, Transmitter Gain, Receiver Gain, Frequency, and Distance into the Friis Transmission Equation Calculator to find the Received Power at the other end of your wireless link, along with Path Loss and signal Wavelength.

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dBi
GHz
m
dBi

Results

Received Power

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Received Power

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Path Loss

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Wavelength

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Signal Power Budget

Frequently Asked Questions

What is the Friis transmission equation?

The Friis transmission equation calculates the power received by an antenna at a given distance from a transmitting antenna. It accounts for transmitter power, antenna gains, frequency, and distance to determine the received power in free space conditions.

What units can I use for transmitter power?

You can input transmitter power in milliwatts (mW), watts (W), dBm, or dBW. The calculator automatically converts between linear and logarithmic units for accurate calculations.

How does frequency affect received power?

Higher frequencies result in greater path loss and lower received power. This is because higher frequency signals have shorter wavelengths and experience more attenuation over distance.

What is antenna gain and how is it measured?

Antenna gain measures how well an antenna focuses energy in a particular direction compared to an isotropic radiator. It's measured in dBi (decibels relative to isotropic) and can be positive or negative.

Does the Friis equation account for obstacles and reflections?

No, the Friis equation assumes free space propagation with no obstacles, reflections, or atmospheric effects. It provides the theoretical maximum received power under ideal conditions.

What is path loss and how is it calculated?

Path loss is the reduction in power density of an electromagnetic wave as it propagates through space. It's calculated as 20*log10(4πdf/c) where d is distance, f is frequency, and c is the speed of light.

Can I solve for unknown variables using this calculator?

This calculator determines received power when all other parameters are known. To solve for other variables like distance or required transmitter power, you would need to rearrange the Friis equation manually.

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