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A very-small-aperture terminal (VSAT) [1] is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Bit rates, in most cases, range from 4 kbit/s to 16 Mbit/s.
Maritime VSAT is the use of satellite communication through a Very-small-aperture terminal (VSAT) on a moving ship at sea. Since a ship at sea moves with the water, the antenna needs to be stabilized with reference to the horizon and True north, so that the antenna is constantly pointing at the satellite it uses to transmit and receive signals.
It can be seen that, as with any aperture antenna, the larger the aperture is, compared to the wavelength, the higher the gain. The gain increases with the square of the ratio of aperture width to wavelength, so large parabolic antennas, such as those used for spacecraft communication and radio telescopes, can have
An aperture antenna's aperture efficiency is defined as the ratio of these two areas: e a = A e A phys . {\displaystyle e_{\text{a}}={\frac {A_{e}}{A_{\text{phys}}}}.} The aperture efficiency is a dimensionless parameter between 0 and 1 that measures how close the antenna comes to using all the radio wave power intersecting its physical aperture.
The aperture efficiency ranges from 0.4 to 0.8 in practical horn antennas. For optimum pyramidal horns, e A = 0.511., [18] while for optimum conical horns e A = 0.522. [18] So an approximate figure of 0.5 is often used. The aperture efficiency increases with the length of the horn, and for aperture-limited horns is approximately unity.
The Broadband Global Area Network (BGAN) is a global satellite network with telephony owned by Inmarsat using portable terminals. [1] The terminals are normally used to connect a laptop computer to broadband Internet in remote locations, although as long as line-of-sight to the satellite exists, the terminal can be used anywhere.
A microstrip antenna array for a satellite television receiver Diagram of the feed structure of a microstrip antenna array. In telecommunication, a microstrip antenna (also known as a printed antenna) usually is an antenna fabricated using photolithographic techniques on a printed circuit board (PCB). [1] It is a kind of internal antenna.
PM WIN-T provides the communications network (satellite and terrestrial) and services that allows the Warfighter to send and receive information in tactical situations. WIN-T is the transformational Command and Control system that manages tactical information transport at theatre through Company Echelons in support of full spectrum Army operations.