The term spectrum refers to a continuous range of frequencies on which radio can operate. In the United States, the Federal Communications Commission (FCC) regulates not only how much of Janet Jackson can be shown at the Super Bowl, but also how various portions of the radio spectrum can be used. Essentially, the FCC has divided the radio spectrum into dozens of small ranges called bands and restricted certain uses to certain bands. For example, AM radio operates in the band from 535 KHz to 1,700 KHz.
The following table lists some of the most popular bands. Note that some of these bands are wide — for example, UHF television begins at 470 MHz and ends at 806 MHz, but other bands are restricted to a specific frequency. The difference between the lowest and highest frequency within a band is called the bandwidth.
| Band | Use |
|---|---|
| 535 KHz–1,700 KHz | AM radio |
| 5.9 MHz–26.1 MHz | Short wave radio |
| 26.96 MHz–27.41 MHz | Citizens Band (CB) radio |
| 54 MHz–88 MHz | Television (VHF channels 2 through 6) |
| 88 MHz–108 MHz | FM radio |
| 174 MHz–220 MHz | Television (VHF channels 7 through 13) |
| 470 MHz–806 MHz | Television (UHF channels) |
| 806 MHz–890 MHz | Cellular networks |
| 900 MHz | Cordless phones |
| 1850 MHz–1990 MHz | PCS cellular |
| 2.4 GHz–2.4835 GHz | Cordless phones and wireless networks (802.11b and 802.11g) |
| 4 GHz–5 GHz | Large dish satellite TV |
| 5 GHz | Wireless networks (802.11a) |
| 11.7 GHz–12.7 GHz | Small dish satellite TV |
Two of the bands in the spectrum are allocated for use by wireless networks: 2.4 GHz and 5 GHz. Note that these bands aren’t devoted exclusively to wireless networks. In particular, the 2.4-GHz band shares its space with cordless phones. As a result, cordless phones can sometimes interfere with wireless networks.
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Source:http://www.dummies.com/how-to/content/wireless-network-administration-spectrums-and-the-.html
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