Enter the frequency of the radio wave and the distance between antennas into the calculator to determine the free space path loss.

## Free Space Path Loss Formula

The following formula is used to calculate a free-space path loss.

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

- Where FSPL is the free space path loss
- d is the distance between antennas (m)
- f is the frequency of the radio wave (hz)
- c is the speed of light 299 792 458 (m/s)

## Free Space Path Loss Defintion

A free-space path loss is the attenuation of radio energy between the feed-points of two antennas.

## How to calculate free space path loss?

**Example Problem #1: **

First, determine the distance between antennas. In this example, the distance between the two antennas’ feed points is measured to be 3000 meters.

Next, determine the frequency of the radio waves being transmitted. In this example, the frequency of the waves is measured to be 5000hz.

Finally, calculate the path loss using the formula above:

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

= (4*3.14159*3000*5000/299,792,458)^2

= .39533.

**Example Problem #2: **

In this next example, the distance between antennas is found to be 10,000 meters and the frequency is 8,000 hz.

Using the same formula as before:

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

= (4*3.14159*10000*8000/299792458)^2

= 11.244