Radio waves - Definition and Overview

Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. Such frequencies account for the following parts of the spectrum:

Band name	Abbr	ITU band	Frequency	Wavelength
			< 3 Hz	> 100,000 km
Extremely low frequency	ELF	1	3–30 Hz	100,000 km – 10,000 km
Super low frequency	SLF	2	30–300 Hz	10,000 km – 1000 km
Ultra low frequency	ULF	3	300–3000 Hz	1000 km – 100 km
Very low frequency	VLF	4	3–30 kHz	100 km – 10 km
Low frequency	LF	5	30–300 kHz	10 km – 1 km
Medium frequency	MF	6	300–3000 kHz	1 km – 100 m
High frequency	HF	7	3–30 MHz	100 m – 10 m
Very high frequency	VHF	8	30–300 MHz	10 m – 1 m
Ultra high frequency	UHF	9	300–3000 MHz	1 m – 100 mm
Super high frequency	SHF	10	3–30 GHz	100 mm – 10 mm
Extremely high frequency	EHF	11	30–300 GHz	10 mm – 1 mm
			Above 300 GHz	< 1 mm

Note: above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that the atmosphere is effectively opaque to higher frequencies of electromagnetic radiation, until the atmosphere becomes transparent again in the so-called infrared and optical window frequency ranges.

The ELF, SLF, ULF, and VLF bands overlap the AF (audio frequency) spectrum, which is approximately 20–20,000 Hz. However, sounds are transmitted by atmospheric compression and expansion, and not by electromagnetic energy.

Electrical connectors designed to work at radio frequencies are known as RF connectors. RF is also the name of a standard audio/video connector, also called BNC (Bayonet Neill-Concelman).

Named frequency bands

• Band III - 174–245 MHz
• ISM band......specific frequencies vary

Microwave (IEEE US)

L band	1 to 2 GHz
S band	2 to 4 GHz
C band	4 to 8 GHz
X band	8 to 12 GHz
Ku band	12 to 18 GHz
K band	18 to 26 GHz
Ka band	26 to 40 GHz
V band	40 to 75 GHz
W band	75 to 111 GHz

See also

• Radio propagation

External links

• Radio and light waves conversion: frequency to wavelength and back (http://www.sengpielaudio.com/calculator-wavelength.htm)