How far can the FM transmitter transmit? How to calculate it?

2. FM Transmitter Power vs Range

Assuming the antenna has a clear view, the frequency is clear and an average quality portable receiver is used, typical transmission power range figures are as follows:

3. How to Calculate Radio Transmitter Range

Items you will need:
· Measurement of the height of the broadcast antenna
· Measurement of the wattage of the radio broadcast

A logarithmic formula is used to calculate the loss of a signal strength over a set distance. The basic formula is 10n * log10 (d) + C, where d is the distance of the transmission, n is the path loss exponent and C is a constant. For a broadcast of 6 watts, the transmission range will be 3 miles. At 15 watts, the range increases to 5 miles, at 40 watts to 10 miles and at 100 watts to 15 miles. The general rule of thumb is it will take four times the power to double the transmission distance.

4. How to increase FM Transmitter Range

Solution 1 – Correctly Position the FM Transmitter
Place the FM transmitter and antenna in a place with less obstructions, such as a flat terrain or a place with high altitude.

Solution 2 – Increase the power of the FM transmitter
In addition to changing the position of the transmitter to reduce the influence of these factors, we can also increase the transmission distance of the FM radio transmitter through high-quality products.  This is the most direct way to increase the transmission distance of the transmitter. The greater the power, the wider the transmission range. Fmuser.org is a professional manufacturer of transmitters and related products, where you can get higher quality products at a more favorable price.

long range FM transmitter   

Solution 3 -  To maximize the effective height of antenna
Communication distance and the square root of the product of the effective height of T/R antenna is proportional. Improving the antenna effective height can significantly expand the communication distance, especially in the urban environment, setting the antenna in the roof can avoid a lot of obstacles and away from sources of interference, thus, expanding the scope of communication.
 
Solution 4 - Use high-gain antenna
Antennas are passive devices, which itself can’t amplify the signal, but the high-gain antennas can significantly improve the communication direction of the energy density, improve the signal / noise ratio, then, expanding the scope of communication. Its role is similar with the flashlight searchlight condenser.
Transmitter using high-gain directional antennas can significantly improve the communication direction of the signal strength. The receiver uses a high gain directional antennas can significantly improve the communication direction of the received signal field strength and signal / noise ratio. Thus significantly expand communication distance. But only for the same direction communication, and the cost is quite high, the antenna geometry large, weight is also heavier, only suitable for fixed installation.

FM dipole antenna 

 
Solution 5 - Try to shorten the length of RF cables
The RF coaxial cable which is used to connect to the wireless communication equipment and an outdoor antenna has a certain degree of loss RF signals. For example, 50-3 cable loss of 0.2dB / m, 50-7-type cable loss of 0.1dB / m , 50-9-type cable loss of 0.07dB / m. The longer of the cable is, the greater loss. The increase of the loss transmit RF signal will lead to a decline of the communication distance. Therefore, RF components can be mounted directly to the bottom of the outdoor antenna when it is necessary. The connection between the RF components and user's system is a multi-core shielded cable.

Solution 6 - Using Studio Transmitter Link (STL)
Studio Transmitter Link ( STL) can help any place where you have resources to become a radio station, so that the connection between your studio and the radio station is not affected by mountains, trees, and building obstacles. Even the height of the transmission tower you rent is only 1/3 of the surrounding buildings,you also can create an exclusive radio station perfectly.

FM Studio Transmitter Link

Solution 7 - Using FM Radio Broadcast Relay System
Many users also call it as local: fm relay station, broadcast relay station, relay transmitter, complementary station, broadcast translator, repeater, re-broadcaster. STL can only be point to-point. If there is a one-to-many point, multiple sets of STL systems must be used, and the price is high, the installation is troublesome, and it is seriously affected by the environment. Now we only need to install the Relay broadcasting system at different transmitter sites, which solves the problem of program transmission and also solves the problem of broadcasting stations, because FM broadcast relay system is not only a receiver but also a broadcaster.

FM Radio Broadcast Relay System