AM expanded band

The extended mediumwave broadcast band, commonly known as the [AM] expanded band, is a broadcast frequency allocation. It moves the upper limit of the AM bandplan from 1605 to 1705 kHz. 

The band became officially available around 1993, but only in ITU region 2 (the Americas). It is popular with micro-broadcasting for having less interference due to fewer signals than the standard/legacy AM band.

Though supported on most modern AM radio receivers sold in the Americas, this band is usually unavailable to older receivers except for those with substantial extended coverage. On such radios, the 1600–1700 segment was labeled "Police", since it was the original police radio band. In the U.S., coverage on newer radios is mandated by the Federal Communications Commission (FCC), invoking the All-Channel Receiver Act.

In the United States of America, the Federal Communications Commission voted to support an expanded band on April 12, 1990. The FCC granted "stereo preferences" to commercial broadcasters intending to use AM stereo when issuing licenses for the band. However, such stations have never been required to broadcast in stereo. With the content of the AM band evolving more toward talk radio than music, it is unlikely that the FCC would take any action against an extended-band station only broadcasting in monophonic sound.

The standard for FCC licensed expanded band stations has been to broadcast omnidirectionally with ten kilowatts of power in the daytime and one kilowatt at night—except for stations that use antennas with higher than normal efficiency or those multiplexed with an existing station on a different frequency. In those cases, they are, by FCC Part 73 rules, authorized for less than one kilowatt at night, generally limiting such stations to 281 millivolts per meter per kilowatt at one kilometer, the minimum efficiency for a Class B station. One station, KVNS 1700 kHz, licensed to Brownsville, TX, operates at 12% less than the standard (8.8KW Day and 880 watts at night) due to treaty obligations with Mexico.

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