Which has the higher frequency range am or FM?

Answer 1

Both can use the same amount of energy. The amount of energy used varies and depends entirely on the tower and the range it was built to cover.

There have been AM and FM towers built to use up to 500kw in the past.

Modern stations now have government limitations placed on them restricting the energy used. Most current AM towers are restricted to 50kw and FM stations are typically restricted to 100kw.

A few older FM towers with a range up to 500kw are still in use today, grandfathered in under the new laws. The only AM towers broadcasting at 500kw were taken over by the military and public towers are no longer allowed to use that much energy.

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The primary differences between AM and FM are not the amount of energy they use but the methods they broadcast with.

AM and FM broadcast at completely different frequencies and bandwidths. An AM station broadcasting at 500kw can cover the entire planet. An FM station broadcasting at 500kw cannot.

AM's frequency and broadcast method allows for the signal to curve and still remain usable at longer ranges for less energy. However, it will always be prone to static and interferance.

FM's higher frequency and larger bandwidth allows for a clearer signal, but the shape of that signal does not bend well and thus does not curve easily around the Earth, regardless of how much energy is dumped into it.

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In either case, the more energy dumped into AM or FM and the longer the range you can reach, but FM is eventually limited more by the curve of the Earth and AM will always be prone to interferance.

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The bottom line, neither AM nor FM has "more energy" simply because they are AM or FM, they have more energy based purely on the design of the tower being used to create the signal and the range it is intended to cover.

Either can use an energy range of 500kw (or theoretically even more), there is simply no reason to in most cases.

With modern government regulations standard AM towers are 50kw, standard FM towers are 100kw. But without the regulations there are no real limits and there are still towers in use on the planet that existed prior to the regulations which broadcast using more energy.

Answer 2

The power (energy per second) of a radio transmission is determined by the frequency and the size of the coverage area. AM startions tend to use more power, partly because a lot of radiated power is sent up into the air.

In the UK AM stations radiate between under 1 kW for local stations up to 300 kW for the long-wave radio-4 transmission.

FM stations tend to use less power because it possible to beam the energy into a volume like a thick pancake so that more of the power reaches the intended audience and less goes upwards. The typical main BBC stations on FM radiate 200 kW but the transmitters might have to produce only 20-30 kW, the rest coming from the directivity of the antenna.

Answer 3

Standard AM bandwidth is 10KHz, standard FM bandwidth is 200MHz.