In this article we calculate the distance covered by a 1000 Watt FM Transmitter.
FM transmitters are used in many different broadcast applications. When planning a system a radio engineer needs to know how far a broadcast will reach. We created a tool to make this easy.
FM Transmitter Range Calculator
In the calculator below, enter:
- Transmitter power 1000 Watt (converts to 60 dBm)
- Receiver sensitivity (refer to the second table below with dBm values for Rural, Urban or Large City)
- Transmit Antenna Gain
- Receive Antenna Gain
According to the ITU, the following table shows required sensitivity in dBuV/m for FM in various environments. We have used the dBuV/m to V/m calculator to convert the units.
|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. As well, for FM, the frequency range is 88-108 MHz, so we have used 108 MHz in the computation.
|Environment||Field Strength (V/m)||Power (dBm)|
Note that cities are more challenging RF environments, so the required power is higher relative to a rural environment. There’s a 20 dB difference between the two. These are receiver sensitivity values that can be substituted in the range calculator above.
What is the Range of a 1000 Watt FM Transmitter?
Based on the calculation above, the range for different operating environments is:
- Rural – 350 km or 218 miles
- Urban – 88 km or 55 miles
- Large City – 35 km or 22 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.