Roumoules radio transmitter
The Roumoules transmitter is the main broadcasting facility for longwave and mediumwave broadcasting of Radio Monte Carlo near Roumoules, France and is owned by Monaco Media Diffusion. The 1000 and 2000kW transmitters installed are among the most powerful in the world and can be received well at nighttime throughout Europe.
Longwave transmitter
The longwave transmitter at Roumoules, which was inaugurated in 1974, transmits at 216 kHz with a transmission power of 1400 kW. It consists of two 1000 kW transmitters switched in parallel, which are however run with 700 kW output power. A third 1000 kW unit has been available since 1983. Although this unit is only used as backup unit, it is possible to switch all three units in parallel, which would allow an operation with a transmission power of 3000 kW. Since the 31st of March 2020 the transmitter has ceased transmitting the French programme of Radio Monte Carlo but remains available for contract use.The longwave transmitter uses a directional aerial with a maximum strength pointing northwest. It consists of three -high guyed masts, which are insulated against ground and ground-fed. As a backup a -high guyed, ground-fed lattice steel mast radiator is available on the site, which only allows an omnidirectional radiation pattern.
The grounding system of the long wave transmitter is very large. The total length of all wires of the grounding system is, covering an area of. Because the area around the mast is used for agriculture, the ground wires are laid to a depth of.
Medium wave transmitter
In 1987 a switchable directional antenna consisting of five ground-fed guyed masts was built nearby for the 1467 kHz medium wave frequency, which was previously transmitted from a transmitter at La Madonne. This antenna allows a switchable directional radiation in the following directions:| Destination | Azimuth |
| Scandinavia | 25° |
| Eastern Europe | 85° |
| Italy and Greece | 150° |
| Spain, Portugal, Northern Africa | 241° |
| UK | 325° |
Changing the signal direction takes only 5 seconds. There are no matching network buildings at the bottom of the masts used for medium wave transmission - the devices for tuning the masts to the transmission line are placed in the open air, similar to those in the longwave antenna system.
The medium wave Roumoules transmitter has an output power of 1000 kW. It is also used for transmitting the religious programmes of Trans World Radio. In comparison to the longwave transmitter, which can be received well both at day and night in Southern France, Northern Italy, Switzerland and Southern Germany, this transmitter cannot be normally received well more than from Roumoules. However at night its transmissions may have at least the same range as those of the longwave system due to its skywave propagation.