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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.
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.
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
The satellite had to be built in a very specific shape and weight, so it could be used in place of one of the launch vehicle ballast weights. OSCAR 1 was the first satellite to be ejected as a secondary payload (the primary payload was Discoverer 36) and to subsequently enter a separate orbit. It carried no on-board propulsion and its orbit ...
A high-throughput satellite (HTS) is a communications satellite which provides more throughput than a classic fixed service satellite (FSS). An HTS provides at least twice, though usually 20 times or more, [1] throughput for the same amount of allocated orbital spectrum, thus significantly reducing cost-per-bit. [2]
In India, the BSE (Bombay Stock Exchange) and NSE (National Stock Exchange) use VSATs (Very Small Aperture Terminals) for members (e.g. stockbrokers) to connect to their trading systems. VSATs depend upon satellites for connectivity between the terminals/systems. Hence, these exchanges are, with considerable predictability, affected by sun outages.
d is the diameter of the cylindrical horn aperture L is the slant height of the cone from the apex λ is the wavelength. An optimum horn does not yield maximum gain for a given aperture size. That is achieved with a very long horn (an aperture limited horn). The optimum horn yields maximum gain for a given horn length. Tables showing dimensions ...