Free-Space Path Loss (using frequency)

The Free-space Path Loss calculator computes the loss of signal strength on a line-of-sight path which has no obstacles or other disturbances based on the distance (d) and the frequency (f) of the signal.  

INSTRUCTIONS: Choose units and enter the following:

• (d) Distance Between Receivers
• (f) Frequency of Signal

Free-Space Path Loss (FSPL): The calculator returns the loss in dB.  However, this can be automatically converted to a real or percent via the pull-down menu.

The Math / Science

The formula for the Free-Space Path Loss using frequency is:

FSPL = `((4 pi * d*f)/c)^2`

where:

• FSPL = Free-space path loss
• d = distance between receivers
• f = frequency of the signal.
• c = Speed of Light

This equation uses the frequency and the constant for speed of light to calculate the FSPL.

This equation is only accurate at a distance from the transmitter where spherical spreading can be assumed.  This equation is not accurate for short distances.

Related Calculators

• Free-Space Path Loss (wavelength): This computes the FSPL as function of wavelength instead of frequency.
• Free-Space Path Loss (using frequency)
• Fiber Optic Cable dB Loss Budget Calculator: 
• Compute Frequency from Wavelength
• Compute Wavelength from Frequency