FORMAL RF BAND DESIGNATORS

The rf spectrum is split into eight bands, each representing one order of magnitude in terms of frequency and wavelength. These bands are called very low, low, medium, high, very high, ultrahigh, superhigh, and extremely high frequencies. They are abbreviated, respectively, as VLF, LF, MF, HF, VHF, UHF, SHF, and EHF. These are depicted in Table 1 in terms of the frequency and the free-space wavelength.
These bands have alternative names. Energy at VLF and LF is sometimes called longwave radio or long waves. Energy in the HF range is sometimes called shortwave radio or short waves (even though the waves aren’t short compared with most EM waves in wireless communications used today). Superhigh-frequency and extremely-high-frequency rf waves are sometimes called microwaves.

Table 1 The Bands in the Radio-frequency (rf) Spectrum. Each band spans one mathematical order of magnitude in terms of frequency and wavelength.

Radio-frequency waves propagate through the Earth’s atmosphere and through space in various ways, depending on the wavelength. Some waves are affected by the ionosphere; this is especially true at VLF, LF, MF, and HF. The troposphere can bend, reflect, or scatter waves at VHF, UHF, SHF, and EHF.

مواضيع ذات صلة

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Radiation

Electromagnetism

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