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How many watts would be needed to cover a 10 mile radius with good sound for music on the 88-108 MHz FM broadcast band? I am an amateur and for fun only.

Muze
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    Do you mean the 88-108 MHz FM broadcast band? The transmission of music is prohibited on any amateur band. Legal issues aside, the antenna will make a lot of difference with a given power. – Mike Waters Jan 26 '17 at 19:56
  • @MikeWaters I will be an amateur at this and will remix all the music as a non profit radio station. – Muze Jan 26 '17 at 21:35
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    Since this is now neither about general radio theory nor about amateur radio, it's become off-topic. – Marcus Müller Jan 27 '17 at 00:14
  • This is off-topic for sure, but you would need a LPFM license and plenty of power, with the antenna at a reasonable height. Everyone always wants to minimize the amount of money but what you are proposing is commercial-level, and that will not be inexpensive. – SDsolar Jan 29 '17 at 05:41
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    @MarcusMüller Non-profit radio is not amateur radio? "amateur ˈamətə,ˈamətʃə,ˈamətʃʊə,ˌaməˈtəː/ noun 1. a person who engages in a pursuit, especially a sport, on an unpaid basis. "it takes five years for a top amateur to become a real Tour de France rider" synonyms: non-professional." Please let this question stand, I am interested in the answers. – user400344 Feb 07 '17 at 21:27
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    @user400344 no, it isn't. Please don't try to argue about the meaning of "amateur radio" on the ham stack exchange. Not every non-profit radio is amateur radio. That's not how language works. – Marcus Müller Feb 07 '17 at 21:31
  • @MarcusMüller No need to block the question, he is interested in propagation per watt with various antennas and all that this entails. I am interested in the data, not quoting a thesaurus to a moderator. – user400344 Feb 07 '17 at 21:34
  • @user400344 I'd love to agree with you, but this is a bad question on so many levels that being off-topic due to being explicitly against the definition of on-topicness for this site is the least one; it's underdefined, it asks for a product recommendation ("how much money do I have to spend?"), it shows no research effort and can't be answered without OP defining what "good sound" actually is. So yes, there is a need to vote for question closing, since that is how community based quality assurance works on StackExchange. – Marcus Müller Feb 07 '17 at 21:38
  • @MarcusMüller I concede. Is it impossible to message OP via SE? I have a few pointers for him that are only pollution of public thread. – user400344 Feb 07 '17 at 22:51
  • I do not want to go commercial but more public in this endeavor. We are allowed to pay ourselves a salary under a non-profit status. – Muze Feb 07 '17 at 23:13
  • @Muze commercial interest is totally irrelevant to the problem at hand – you're asking about non-amateur operation (namely, music) in a non-amateur band. – Marcus Müller Feb 08 '17 at 07:19
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    @Mike Waters: In my country, transmission of music on some amateur band but only for test transmissions is allowed. – Tom Kuschel Feb 08 '17 at 17:49

2 Answers2

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This is a link budget question. Transmit power is just one factor: others are terrain, antennas, frequency, quality, noise, and so on.

If we restrict the variables to typical values for FM commercial broadcast stations, we can use the FCC's rules to make some estimations. By that reckoning, you need a transmitter of around 50kW with an antenna 150 meters high to achieve your goal of high-quality coverage over a 20 mile radius.

Unfortunately, that's a very expensive transmitter. And you need a commercial license.

Community
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Phil Frost - W8II
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This depends in your intended communication. Are you trying to hit a fixed receiver, in which case you can aim an antenna to that receiver? or are you trying to communicate with a handheld or other portable system? Are you on a portable system? Is the target system on a hill? The gain on the receive antenna, as well as the radiation pattern of your antenna makes a huge difference.

Additionally, the actual band used may make a difference. Many different bands permit FM operation, and some have unique properties that increase propagation distance.

Often, a 5w handheld with a rubber duck can hit a repeater ~10-20 miles away, but this is one particular example of possible communication.

Edit:

As you mentioned that you want good quality for music, you'll really need a more powerful transmitter. Unfortunately, FCC part 97 (Amateur) rules disallow music through the amateur radio bands, so you'll likely need a commercial FM broadcast license to do that sort of thing.

I'm not qualified to talk at length about the particulars of antenna design, but there are other resources online. For broadcast FM radio, you'll need an antenna (a) in a high location, so receivers can clearly receive your signal; (b) high power, usually on the order of kilowatts. (WCBN-FM, a student radio station in Ann Arbor MI, uses a 200W transmitter, but has an effective range of around 10 miles).

Tyzoid
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