I copied this straight from the FCC website
Unlicensed Operation Is Prohibited. A very common question asked of the FCC is whether broadcasting at very low power requires a license. Please be aware that unlicensed operation of radio broadcast stations is prohibited, even at low powers such as 1 watt or less. The only unlicensed operation that is permitted on the AM and FM broadcast bands is covered under Part 15 of the FCC's rules, and is limited to a coverage radius of approximately 200 feet. (See the Commission's July 24, 1991 Public Notice.) Unlicensed operation is not permitted in the television bands (including 87.9 MHz, which falls within the 82.0 to 88.0 Channel 6 television band). Fines and/or criminal prosecution may result from illegal operation of an unlicensed station (see recent enforcement actions).
URL: http://www.fcc.gov/guides/how-apply-radio-or-television-broadcast-station
So based on this wouldn't my Part 15 am station with a range of 1 mile be illegal because of the 200 foot rule?
5000 feet is approximately 200 feet if you think in dB.
You didn't say whether you are interested in AM or FM so here are the relevant parts of the rules:
AM Part15.209 and Part 15.219
FM Part 15.239
You can web search for these.
The range mentioned in the Public Notice is not a legal statement and it does not mention the conditions for this estimate such as the receiver used. In fact, on AM most operators choose to operate under 15.219 which gives the best range for a legal Part 15 setup. Essentially, the input power is limited, the antenna, feedline, and ground lead lengths are limited but there is no restriction on range. The range depends on the efficiency of the antenna system and the receiver which can be highly variable.
For FM the field strength is limited and the 200 foot or so range is close to what has been experienced by those using certified FM transmitters.
I operate an AM transmitter system under Part 15.219 and have a range as checked with a car radio of 1 mile.
If you will narrow your question a bit we can focus on particular topics.
Neil
FCC Public Notice 14089 dated July 24, 1991 is available through the link in the OP, and appears to contain information that contradicts some of the applicable paragraphs of Part 15. But in any case (IMO) it would/should not have the force of law. It is an advisory notice.
The actual law applying to unlicensed use of the AM/FM broadcast bands is given in FCC paragraphs 15.209, 15.219 and 15.239.
For example, the public notice states that the maximum radiated power for AM is 0.05 watts (50 mW). However that amount of radiated power produces a groundwave field intensity that is far above the nominal 15 µV/m value permitted by §15.209 for the upper end of the AM broadcast band.
The radiated power needed to just meet §15.209 at the upper end of the AM broadcast band is on the order of 2 nW (0.000 000 002 watts). Radiating 50 mW would produce a field at 30 meters that is over 4900 times greater than the ~15 µV/m value meeting §15.209.
FCC §15.219 permits 100 mW (d-c) input power to the final r-f stage, and limits the radiating length of the antenna conductors to 3 meters, including the conducting path to r-f ground.
Probably the intention of the FCC was to provide an alternate way to comply with §15.209 without the need for accurately measuring the fields radiated by these systems -- which probably very few hobbyists are equipped to do.
But in reality, a system meeting §15.219 can produce much higher radiated fields at a distance of 30 meters than is permitted by §15.209. So these systems, while they might technically be compliant to a given set of rules (209 or 219), that doesn't necessarily mean that they will have the same radius to a given, groundwave field intensity.
(Written before reading Neil's statement above, but really there is no conflict between our two posts.)
I think these public notices are there to deture interest in part 15 operation.
Which by the way... has worked for years, I use myself as an example.
I hadn't started a station for years because the FCC's own website tells me that its 200' for both AM and FM. Now, as mentioned in the "legal text" its a completely different game.
Which is why I now intend to operate such a station, but if not for myself taking the time to go find the law I never once would've looked into it much further.
Hopefully I'm on the air over the next few days, just waiting on the transmitter.
Good luck to the OP
I have to wonder how many others are put off by the "official" range statements.
This site is a great resource to find out what actually works and how to do it.
Neil
The practice of law is based on a very codified system that amounts to a whole other language requiring years of law school.
The language of law is crafted to be unclear to the common person as a job insurance for lawyers.
Lawyers are commercial professionals and so would be unlikely to contribute helpful input to Part 15 sites such as this.
The closest thing to an expertise are the several veteran radio engineers who contribute here, and we are fortunate to have access to their opinions from experience.
However, I freely and frequently question the Part 15 rules because even the most sincere opinions and beliefs expressed here are subject to question.
An open mind is a living mind.