In this article we calculate the distance covered by a popular FM Transmitter.
FM transmitters are used in many different applications like outdoor drive in movie theaters. A typical FM transmitter has a maximum output between 0.1 Watt and 25 Watt. The one below transmits at 15 Watt.
FM Transmitter Range Calculator
In the calculator below, enter:
- Transmitter power 15 Watt (converts to 42 dBm)
- Receiver sensitivity (consistent with Rural, Urban or Large City)
- Transmit Antenna Gain
- Receive Antenna Gain
|Environment||Field Strength (dBuV/m)||Field Strength (V/m)|
The field strength is used to calculate the input power at the receiver in dBm. In this case the antenna gain of 0 dBi is used. However you can substitute any value in this calculator.
The FM frequency range is 88-108 MHz.
|Environment||Field Strength (V/m)||Power (dBm)|
Note that cities are more challenging RF environments, so the required power for a certain level of performance is higher relative to a rural environment. There’s a 20 dB difference between the two. The receiver sensitivity values that can be substituted in the range calculator above.
What is the Range of a 15 Watt FM Transmitter?
Based on the calculation above, the range for different operating environments is:
- Rural – 44 km or 27.5 miles
- Urban – 11 km or 6.9 miles
- Large City – 4.4 km or 2.75 miles
As would be expected the range is the lowest in a city where buildings and other large objects will obstruct the FM signal. This means it will not travel as far in a city as it will in a rural environment.