What is VSAT (Very Small Aperture Terminal)?

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Editorial Team - everything RF

Apr 6, 2019

A Very Small Aperture Terminal (VSAT) is a device that transmits to and receives signals from a satellite. The dish antenna we see in houses for D2H or at the top of tall buildings is a simple example of a VSAT terminal. 

A VSAT has two parts, an outdoor unit and an indoor unit. The outdoor unit that consists of a dish antenna (reflector), the feed, the Block Upconverter (BUC) and the Low Noise Block Downconverter (LNB). The indoor unit consists of the satellite modem and an IP router which connects to a computer or an Ethernet Interface.

During transmission, the indoor unit sends the signal/data to the BUC (Block Up Converter) which upconverts the signal, amplifies it and sends it out to the satellite via the dish antenna.

When receiving data/signals, the VSAT Antenna receives a signal, sends it to a Low Noise Block (LNB) which filters, amplifiers and down-converts the signal and send sends it to the Satellite modem for further processing.

The size of the antenna depends on the frequency band and the link budget. The link budget can be calculated based on the power requirements, antenna size, bandwidth requirements and a number of other factors.

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