Glossary - V

Van Allen belts
a belt of radiation (consisting mainly of protons and electrons) encircling a planet, trapped by the planet’s magnetosphere and originating mainly from the solar wind; the Earth has two Van Allen belts which extend from an altitude of 640 to 58,000 km
(planetary science)

Very High Frequency (VHF)
radio band with frequencies in the range 30 to 300 MHz
(physics)

Visible light
a form of electromagnetic radiation between ultraviolet and infrared in the electromagnetic spectrum; visible light has a wavelength between about 380 and 700 nm
(physics)

Voltage Standing Wave Ratio (VSWR)
numerical ratio of the maximum voltage to the minimum voltage that would exist on a transmission line
(technology)

VSAT
Very Small Aperture Terminal; a one or two-way network generally consisting of several (sometimes several thousand) small remote terminals and a large central hub; generally all communications are between the remote terminals and the hub, if two terminals wish to communicate the messages must be relayed via the hub; however some VSATs networks are configured as a mesh in which the remote terminals can communicate directly with one another or as point to point links in which pairs of remote terminals are assigned permanent one to one connections
(satellite communications)