FCC Rules About AM Transmitters

The Federal Communications Commission (FCC) regulates all types of broadcasting in the United States. This includes television, commercial radio, citizens band radio and other broadcast sources. The commission's rules and regulations are complicated and extensive. However, it is helpful for those interested in the AM radio dial to understand a few basics. Part 15 of the FCC rules pertains to those who want to transmit without a license.

Low-Power, Non-licensed Transmitters
Under Part 15 of the FCC rules, any American citizen may legally operate a low-power radio station on the AM radio broadcast band without a broadcast license. Many people and institutions take advantage of this, such as universities, schools, parks, campgrounds, real estate offices and shopping malls. Citizens are allowed to transmit as a hobby or for profit.

AM Power
While anyone can broadcast on the AM dial, the transmission power they can use is limited. The power is restricted to 100 milliwatts, and there are also limits on the height, size and type of antenna than can be used. If the broadcasting is done from an educational institution, there are no limits on the power as long as it doesn't go over the field strength limits, which are 24000/fkHz µV/m.

Although the operator doesn't need a license to transmit, the transmitter itself must be authorized by the FCC before the manufacturer can sell it on the open market. This is to make sure the transmitters comply with the technical standards set out by the FCC and won't cause any interference with authorized AM radio stations. Even if the transmitter is authorized, if it creates interference, the user will be asked to cease broadcasting operations until the problem is fixed.

Antenna Requirement
Different sizes and types of antenna can sharply increase or decrease the strength of a broadcasting signal. The antenna in low-powered AM broadcasting must meet FCC standards so the signal doesn't interfere with authorized radio channels or emergency and air-traffic control systems. The rules state that only authorized antennas can be used. This means the antenna must be permanently attached or is a detachable antenna that comes with unique connectors that aren't found in electronic supply stores. Part 15 lets people replace a broken antenna with an identical one.

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