Frequency allocation

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United States radio spectrum frequency allocations chart as of 2011
United States radio spectrum frequency allocations chart as of 2003

Use of radio frequency bands of the electromagnetic spectrum is regulated by governments in most countries, in a Spectrum management process known as frequency allocation or spectrum allocation. Radio propagation does not stop at national boundaries. Giving technical and economic reasons, governments have sought to harmonise the allocation of RF bands and their standardization.

A number standards bodies work on standards for frequency allocation, including:

These standards bodies have assigned frequency bands in three types of allocation:

High-demand sections of the electromagnetic spectrum may sometimes be allocated through auctions.

Daily impact[edit]

Every day, users rely on allocation of frequencies for efficient use of such devices as:

Power levels vary widely (from 1 milliwatt in a Bluetooth node to 1 kilowatt in a microwave oven). While the general RF band controls propagation characteristics, who uses what is arbitrary and historical. A particular frequency may require line of sight, or may be attenuated by rain, but whether it carries ambulance or pizza delivery traffic depends on what region it is used in.

Earlier equipment could not process higher frequencies, nor was it compact enough to support certain uses. Over time the exploitable frequencies have increased and semiconductors have shrunk. A tube radio is neither mobile nor reasonably battery powered; GPS works at 1,500 MHz and fits in a pocket. A Bluetooth headset can talk to a mobile phone which is trunked on a microwave link, and at the other end someone is on a cordless phone.

International conventions[edit]

The range of "radio frequencies" is a matter of international convention. The separation of countries into the three formal ITU RF allocation regions is one source of different RF allocation policies in different parts of the world. The definition of the ITU Regions is based largely on longitude. According to ITU Radio Regulations section 5.1: Member States assign licenses to stations; article 5 of the ITU regulations allocates frequencies to services (such as broadcasting and mobile). The ITU divides the world into five administrative regions:

the Americas,
Western Europe,
Eastern Europe and Northern Asia,
Africa, and
Asia and Australasia.

The ITU also categorises states into three Radio regulatory Regions:

Region 1
Europe, Middle East, Africa, the former Soviet Union, including Siberia; and Mongolia;
Region 2
North and South America and Pacific (East of the International Date Line);
Region 3
Asia, Australia and the Pacific Rim (West of the International Date Line).

Thus, the RF allocations fundamentally differ between continents. Longitude may traverse continents, for example, the 40°E meridian crosses Europe (Russia), Asia (Middle East) and Africa.

The division between Europe and the other regions is the root of the different RF allocations in the ITU Radio Regulations, and standards around the world. ITU-R Study group 1 details how and why there are three separate Regions.[1]

See also[edit]


External links[edit]