Radio spectrum

Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits or electromagnetic radiation.

Contents 1 Special properties of RF electrical signals 2 Frequencies 3 See also 4 External links

Special properties of RF electrical signals

Electrical currents that oscillate at RF have special properties not shared by direct current signals. One such property is the ease with which it can ionize air to create a conductive path through air. This property is exploited by 'high frequency' units used in electric arc welding. Another special property is an electromagnetic force that drives the RF current to the surface of conductors, known as the skin effect. Another property is the ability to appear to flow through paths that contain insulating material, like the dielectric insulator of a capacitor. The degree of effect of these properties depends on the frequency of the signals.

Frequencies

Name	Symbol	Frequency	Wavelength	Applications
Extremely low frequency	ELF	a 3 to 30 Hz	k 10,000 km to 100,000 km	directly audible when converted to sound, communication with submarines
Super low frequency	SLF	b 30 to 300 Hz	j 1,000 km to 10,000 km	directly audible when converted to sound, AC power grids (50 hertz and 60 hertz)
Ultra low frequency	ULF	c 300 to 3000 Hz	i 100 km to 1,000 km	directly audible when converted to sound, communication with mines
Very low frequency	VLF	d 3 to 30 kHz	h 10 km to 100 km	directly audible when converted to sound (below ca. 18-20 kHz; or "ultrasound" 20-30+ kHz)
Low frequency	LF	e 30 to 300 kHz	g 1 km to 10 km	AM broadcasting, navigational beacons, lowFER
Medium frequency	MF	f 300 to 3000 kHz	f 100 m to 1 km	navigational beacons, AM broadcasting, maritime and aviation communication
High frequency	HF	g 3 to 30 MHz	e 10 m to 100 m	shortwave, amateur radio, citizens' band radio
Very high frequency	VHF	h 30 to 300 MHz	d 1 m to 10 m	FM broadcasting, broadcast television, aviation, GPR
Ultra high frequency	UHF	i 300 to 3000 MHz	c 10 cm to 100 cm	broadcast television, mobile telephones, cordless telephones, wireless networking, remote keyless entry for automobiles, microwave ovens, GPR
Super high frequency	SHF	j 3 to 30 GHz	b 1 cm to 10 cm	wireless networking, satellite links, microwave links, Satellite television, door openers.
Extremely high frequency	EHF	k 30 to 300 GHz	a 1 mm to 10 mm	microwave data links, radio astronomy, remote sensing, advanced weapons systems, advanced security scanning

See also

• Radio waves
• Frequency allocation
• Plastic Sealing/Welding Technologies
• Ultrasound
• RF connector

External links

• Definition of frequency bands (VLF, ELF … etc.) IK1QFK Home Page (vlf.it)
• Radio, light, and sound waves, conversion between wavelength and frequency
• RF eBooks - Some free RF related eBooks
• RF and Telecommunication eBooks
• RF Terms Glossary

v • d • e Radio spectrum ELF 3 Hz 30 Hz SLF 30 Hz 300 Hz ULF 300 Hz 3 kHz VLF 3 kHz 30 kHz LF 30 kHz 300 kHz MF 300 kHz 3 MHz HF 3 MHz 30 MHz VHF 30 MHz 300 MHz UHF 300 MHz 3 GHz SHF 3 GHz 30 GHz EHF 30 GHz 300 GHz

v • d • e Electromagnetic spectrum ← shorter wavelengths       longer wavelengths → Gamma rays · X-rays · Ultraviolet · Visible · Infrared · Terahertz radiation · Microwave · Radio Visible (optical) Violet · Blue · Green · Yellow · Orange · Red Microwaves W band · V band · Q band · Ka band · K band · Ku band · X band · S band · C band · L band Radio EHF · SHF · UHF · VHF · HF · MF · LF · VLF · ULF · SLF · ELF Wavelength types Microwave · Shortwave · Mediumwave · Long wave

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