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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: different purposes. These groupings are usually due to the different physical characteristics or behavior of radio waves at different frequencies. To understand the properties of different radio waves, first calculate the wavelength of some typical radio frequencies found in each of the main broadcast bands. This is performed by dividing the speed of light by the frequency of interest. However, electricity travels at 95% the speed of light in a wire, the number of times the polarity changes in one second (frequency) determines how long the wire has to be in order to be resonant. Radio is divided into bands. The Long Wave Band (LW) starts at 30 kHz and goes to 300 kHz. The Medium Wave Band (MW) is from 300 kHz to 3000 kHz or 3 MHz. The High Frequency Band (HF) is from 3 MHz to 30 MHz. The Very High Frequency Band (VHF) is from 30 MHz to 300 MHz. The Ultra-High Frequency Band (UHF) is from 300 MHz to 3000 MHz or 3 GHz. Above these frequencies are several microwave bands which are defined as the Super High Frequency Band (SHF). [[File:radio-spectrum-summary-A_500.jpg]][[File:radio-spectrum-summary-B_500.jpg]]As this exercise 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. [[File:radio-spectrum-summary-C_500.jpg]] 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. It also helps to visualize the spectrum.=== United States Frequency Allocations Chart ===[[File:radio-spectrum-summary-A.png]]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.[[File:radio-spectrum-summary-B.png]][[Image:United_States_Frequency_Allocations_Chart_ICON.jpg|link=http://wiki.robotz.com/images/4/40/United_States_Frequency_Allocations_Chart.jpg]][[File:radio-spectrum-summary-C.png]]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 =={{:Wavelength_table_ex1}} ''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.''{| class="wikitable"|- ! Band name! Abbreviation! ITU band! Frequency<br />and<br />wavelength in air! Example uses|-| [[Tremendously low frequency]] | style="text-align:center;"| TLF| style="text-align:center;"| | style="text-align:center; white-space:nowrap;"| < 3 [[Hertz|Hz]]<br />> 100,000 km| style="text-align:center;"| Natural and artificial electromagnetic noise|-| [[Extremely low frequency]]| style="text-align:center;"| ELF| style="text-align:center;"| | style="text-align:center; white-space:nowrap;"| 3–30 Hz<br />100,000 km – 10,000 km| style="text-align:center;"|Communication with submarines|-| [[Super low frequency]]| style="text-align:center;"| SLF| style="text-align:center;"| | style="text-align:center; white-space:nowrap;"| 30–300 Hz<br />10,000 km – 1000 km| style="text-align:center;"| Communication with submarines|-| [[Ultra low frequency]]| style="text-align:center;"| ULF| style="text-align:center;"| | style="text-align:center; white-space:nowrap;"| 300–3000 Hz<br />1000 km – 100 km| style="text-align:center;"| Submarine communication, communication within mines|-| [[Very low frequency]]| style="text-align:center;"| VLF| style="text-align:center;"| 4| style="text-align:center; white-space:nowrap;"| 3–30 kHz<br />100 km – 10 km| style="text-align:center;"| Navigation, time signals, submarine communication, wireless heart rate monitors, geophysics|-| [[Low frequency]]| style="text-align:center;"| LF| style="text-align:center;"| 5| style="text-align:center; white-space:nowrap;"| 30–300 kHz<br />10 km – 1 km| style="text-align:center;"| Navigation, clock time signals, AM longwave broadcasting (Europe and parts of Asia), [[RFID]], [[amateur radio]]|-| [[Medium frequency]]| style="text-align:center;"| MF| style="text-align:center;"| 6| style="text-align:center; white-space:nowrap;"| 300–3000 kHz<br />1 km – 100 m| style="text-align:center;"| AM radio (medium-wave) broadcasts, amateur radio, avalanche beacons|-| [[High frequency]]| style="text-align:center;"| HF| style="text-align:center;"| 7| style="text-align:center; white-space:nowrap;"| 3–30 MHz<br />100 m – 10 m| style="text-align:center;"| Shortwave broadcasts, citizens' band radio, amateur radio and over-the-horizon aviation communications, [[RFID]], [[over-the-horizon radar]], [[automatic link establishment]] (ALE) / near-vertical incidence skywave (NVIS) radio communications, marine and mobile radio telephony|-| [[Very high frequency]]| style="text-align:center;"| VHF| style="text-align:center;"| 8| style="text-align:center; white-space:nowrap;"| 30–300 MHz<br />10 m – 1 m| style="text-align:center;" | FM radio, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications, land mobile and maritime mobile communications, amateur radio, weather radio|-| [[Ultra high frequency]]| style="text-align:center;"| UHF| style="text-align:center;"| 9| style="text-align:center; white-space:nowrap;"| 300–3000 MHz<br />1 m – 100 mm| style="text-align:center;" | Television broadcasts, microwave oven, microwave devices/communications, [[radio astronomy]], [[mobile phone]]s, wireless LAN, [[Bluetooth]], ZigBee, GPS and two-way radios such as land mobile, [[Family Radio Service|FRS]] and [[GMRS]] radios, amateur radio|-| [[Super high frequency]]| style="text-align:center;"| SHF| style="text-align:center;"| 10| style="text-align:center; white-space:nowrap;"| 3–30 GHz<br />100 mm – 10 mm| style="text-align:center;"| Radio astronomy, microwave devices/communications, wireless LAN, most modern radars, communications satellites, satellite television broadcasting, DBS, amateur radio|-| [[Extremely high frequency]]| style="text-align:center;"| EHF| style="text-align:center;"| 11| style="text-align:center; white-space:nowrap;"| 30–300 GHz<br />10 mm – 1 mm| style="text-align:center;"| Radio astronomy, high-frequency microwave radio relay, microwave remote sensing, amateur radio, [[Active Denial System|directed-energy weapon]], millimeter wave scanner|-| [[Terahertz]] or [[Tremendously high frequency]]| style="text-align:center;"| THz or THF| style="text-align:center;"| 12| style="text-align:center; white-space:nowrap;"| 300–3,000 GHz<br />1 mm – 100 um| style="text-align:center;"| Terahertz imaging – a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics, [[condensed-matter physics]], terahertz time-domain spectroscopy, terahertz computing/communications, sub-mm remote sensing, amateur radio|}<small><small>frequency band meter</small></small>