Free-space path loss (FSPL) is a measure of the attenuation of a radio signal between two distant antennas, free from obstacles.
It is measured in decibels (dB); the greater the distance, the greater the attenuation, and it is represented by a higher value.
It is measured in decibels of milliwatts (dBm), which is the value relative to 1mW, 1000 times smaller than dB.
For values below 0dB, it is as if there were a power gain.
Enter the transmitted power "Gain TX", the received power amplification (Gain RX), the desired frequency and distance to calculate the FSPL.
You can also set the receiver impedance to estimate the RMS Volt value to be received.
The calculated value is in dB and is truncated below 0 dB so that there is no gain error in relation to the transmitted power.
If you know the value of the attenuation of obstacles, subtract this value from the Transmitted Gain (Gain TX). There are tables on the internet with these values for the most well-known frequencies, such as 2.4GHz (WIFI Radio Waves).
| d | Distance in meters |
| f | Frequency in hertz |
| c | Speed of ligth in meters/s |
| Gain TX | |
| Gain RX | |
| Frequency | |
| Distance | |
| Impedance | |
| Speed of light | |
| Wavelength | |
| FSPL | |
| Power TX | |
| Power RX | |
| Power RX | |
| RMS RX | |
| Vpp RX | |
References:
Wikipedia Free-space path loss