Radio Frequencies, Bands, and Channels
Radio frequency transmissions are divided up into contiguous bands for different purposes. These groupings are usually due to the different physical characteristics or behavior of radio waves at different frequencies (more on this below). To understand the properties of different radio waves, let's first calculate the wavelength of some typical radio frequencies found in each of the main broadcast bands. As explained above, this is performed by dividing the speed of light by the frequency of interest:
- Band: MF — Medium Frequency — AM (amplitude mall/ago/0 Radio Band (535-1705 kHz)
- Channel: AM Radio — 1120 kHz 300 million meters/sec ÷ 1120 thousand cycles /sec = 268 meters (880 feet)
- Band: VHF — Very High Frequency FM Viequeney moduilatiaii) Radio Band (88-108 MHz)
- Channel: FM Radio — 98.1 MHz 300 million meters/sec = 98.1 million cycles/sec = 3 meters (10 feet)
- Band: VHF — Very High Frequency — Television Band (54-216 MHz)
- Channel: VHF TV, Channel 8-183 MHz 300 million meters/sec ÷ 183 million cycles/sec = 1.64 meters (5 feet)
- Band: UHF — Ultra High Frequency — Television Band (470-806 MHz)
- Channel: UHF TV, Channel 40 — 629 MHz 300 million meters/sec ÷ 629 million cycles/sec = 0.48 meters (19 inches)
- Band: SHF — Super High Frequency — Broadcasting Satellite Ku Band (11-14 GHz)
- Channel: Direct Broadcast Satellite, Transponder 30 — 12.647 GHz 300 million meters/sec ÷ 12.647 billion cyclesfsec = 2.37 centimeters (1 inch)
As this summary of the Electromagnetic Spectrum illustrates, the wavelengths of different broadcast bands vary quite a bit, from hundreds of feet to an inch or less. Because of these differing wavelengths, there are major physical differences in the design of antenna types used to transmit and receive signals in different bands. The amplitudes (or power) of these signals also greatly influence the design and size of these antennas.
Each radio band is divided into individual channels, and each of these channels includes a range of frequencies. The range of frequencies included in a channel from lowest to highest is known as the channel's batidwidin. (The term may also refer to any particular range of frequencies, not just those in RF.) For simplicity, however, a channel is often identified by its reizterfrequency, so that only one numerical value (rather than two) will have to be cited when referring to a particular channel. If the center frequency is given and the channel bandwidth is known, the upper and lower frequency limits of the channel can be easily derived. For example, a channel with a 2 kHz (2,000 Hz) bandwidth centered at 100 kHz occupies the spectrum between 99 kHz and 101 kHz.
The UHF and SHF bands have further subdivisions, with bands that are used for terrestrial radio links, satellite links, and for satellite broadcasting. These include the L, Cyan, X, Ku, IC, and Ka bands, with frequencies ranging from about 1 GHz to 40 GHz.
United States Frequency Allocations Chart
The United States Department of Commerce, National Telecommunications and Information Administration (NTIA) - Office of Spectrum Management released this chart to the public in 2003. This is an enormous chart that would make an excellent poster to hang on your wall. It is very detailed. Click the icon below for a direct link to the file.
The NTIA's Office of Spectrum Management is in charge of regulating use of spectrum allocated to the Federal Government. It serves in a manner equivalent to the FCC for this purpose. It is also the part of the Department of Commerce that oversees ICANN.
Wavelength Table
Meter Band Frequency Range and Use -------------------------------------------------- 160 meter 1800-2000 kHz ham radio 120 meter 2300-2498 kHz broadcasting 90 meter 3200 to 3400 kHz broadcasting 80 meter 3500 to 4000 kHz ham radio 60 meter 4750 to 4995 kHz broadcasting 49 meter 5950 to 6250 kHz broadcasting 41 meter 7100 to 7300 kHz broadcasting 40 meter 7000 to 7300 kHz ham radio 31 meter 9500 to 9900 kHz broadcasting 30 meter 10100 to 10150 kHz ham radio 25 meter 11650 to 11975 kHz broadcasting 22 meter 13600 to 13800 kHz broadcasting 20 meter 14000 to 14350 kHz ham radio 19 meter 15100 to 15600 kHz broadcasting 17 meter 18068 to 18168 kHz ham radio 16 meter 17550 to 17900 kHz broadcasting 15 meter 21000 to 21450 kHz ham radio 13 meter 21450 to 21850 kHz broadcasting 12 meter 24890 to 24990 ham radio 11 meter 25670 to 26100 kHz broadcasting 10 meter 28000 to 29700 kHz ham radio 6 meter 2 meter 1.25 meter 70 centimeter 33 centimeter 23 centimeter
Due to errors from HAM designations versus actual wave conversion formula 17-meter ham radio band is actually higher in frequency than the 16-meter broadcasting band.
