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Sec. 8.4 Single-Sideband Sinusoidal Amplitude Modulation 597

Frequency Propagation Channel range Designation Typical uses method features

30-300Hz ELF Macrowave, submarine com- Megametric waves Penetration of conducting (extremely munication . earth and seawater low frequency)

0.3-3 kHz VF Data terminals, telephony Copper wire (voice frequency)

3-30kHz VLF Navigation, telephone, tele- Surface ducting Low attenuation, little fading, (very low fre- graph, frequency and tirning (ground wave) extremely stable phase and quency) standards frequency, large antennas

30-300kHz LF Industrial (power line) com- Mostly surface ducting Slight fading, high atrno-(low frequency) munication, aeronautical

and maritime long-range spheric pulse

navigation, radio beacons 0.3-3MHz MF Mobile, AM broadcasting, Ducting and ionospheric Increased fading, but reliable

(medium frequency) amateur, public safety reflection (sky wave) 3-30MHz HF Military communication, aero- Ionospheric reflecting sky Intermittent and frequency-

(high frequency) nautical mobile, intema- wave, 50-400 km layer selective fading, multipath tional fixed, amateur and altitudes citizen's band, industrial

30-300MHz VHF FM and TV broadcast, land Sky wave (ionospheric and Fading, scattering, and multi-(very high transportation (taxis, buses, tropospheric scatter) path frequency) railroad)

0.3-3 GHz UHF UHF TY, space telemetry, Transhorizon tropospheric (ultra high radar, military scatter and line-of-sight frequency) relaying

3-30GHz SHF Satellite and space commu- Line-of-sight ionosphere Ionospheric penetration, (super high nication, common carrier penetration extraterrestrial noise, frequency) (CC), microwave high directly

30-300GHz EHF Experimental, government, Line of sight Water vapor and oxygen (extremely high radio astronomy absorption frequency)

103-107 GHz Infrared, visible light, Optical communi~ations Line of sight ultraviolet

Figure s. 1 s Allocation of frequencies in the RF spectrum.