What is a spot beam antenna?
A spot beam, in telecommunications parlance, is a satellite signal that is specially concentrated in power (i.e. sent by a high-gain antenna) so that it will cover only a limited geographic area on Earth.
What is the purpose of using a spot beam?
Spot beam technology allows different data to be sent to different locations using the same carrier frequencies. For example, local TV programs can be transmitted to multiple counties within a state; however, the beam footprint is naturally circular and cannot correspond to local jurisdictions.
What is an advantage of using spot beams vice Earth coverage horn antennas?
The benefits of using spot beams Spot beams are more concentrated in power than a wide beam, so those on the receiving end get a stronger signal. Since the coverage area is smaller, there is also a reduced risk of interference with other transmissions using the same frequencies, or interception by third parties.
Which technique uses spot beam?
Which technique uses spot beam antennas to divide the area covered by the satellite into smaller segments? By using narrow beam or spot beam antennas, the area on the earth covered by the satellite can be divided up into smaller segments.
How are spot beam produced?
A spot beam is produced in the same way that a broad beam is, but is focused at a specific area of the Earth’s surface. A spot beam begins as an electrical signal that is converted into a radio frequency by means of a dipole, which is simply two intersecting antennas that vibrate when a current is passed through it.
What is G T ratio in satellite communication?
A parameter often encountered in specification sheets for antennas that operate in certain environments is the ratio of gain of the antenna divided by the antenna temperature (or system temperature if a receiver is specified). This parameter is written as G/T, and has units of dB·K−1. G/T Calculation.
Which type of antennas are most commonly used for the satellite?
Horn antennas. The reflector antenna is most frequently used in communications satellites because of its simple structure, light weight, and high gain (Fig.
How are spot beams produced?
Why downlink frequency is lower than uplink?
In satellite communication, the uplink frequency is higher than the downlink frequency because the attenuation level increase with an increase in frequency. The power at the ground station (Base Station) is more than compared to the power available at the satellite.
Which antenna produce multiple narrow beams?
Parabolic antennas are distinguished by their shapes: Paraboloidal or dish – The reflector is shaped like a paraboloid truncated in a circular rim. This is the most common type. It radiates a narrow pencil-shaped beam along the axis of the dish.
What are the characteristics that are most important in satellite antenna?
The fundamental characteristics of an antenna are its gain and half power beamwidth. According to the reciprocity theorem, the transmitting and receiving patterns of an antenna are identical at a given wavelength.
How is antenna GT calculated?
To calculate the G/T of a receive system we need to compare the gain and system noise temperature, both referenced to the same place. In this case the Gain (G) referenced to the input to the LNB is = Antenna gain (dBi) minus Waveguide loss (dB).
What is difference between C N and G T ratio?
[CN0] is the carrier to noise density ratio. [GT] is the earth station receiver G/T ratio and units are dB/K.
Which frequency should be high uplink or downlink?
Uplink frequency is kept higher than Downlink frequency for the following reasons: At higher frequency attenuation is more hence more power will be required for signal transmission to ensure that it reaches the destination with the required minimum power.