The ground based use radio frequency waves for transmission and reception of the information in between transmitter and the end systems. But radio can be used in satellite communication but they have some distortions, so microwaves are used in satellite communications. In this Satellite Communications Seminar paper we will see the frequency ranges used for transmitting the microwaves and the design of the transmitting systems and the antennas used for satellite communication.
Brief on satellite communications Seminar:
The frequencies to be used in satellite communications are calculated based on the factors of atmospheric absorption and the size of the antenna used and regulations. The absorption factor is calculated as a function of frequency at different altitudes and above the sea level. In absorption factor distortions occurring due to fog or rain are also taken into consideration.
The size of the antenna and the frequency factor are inversely proportional so if the frequency increases the size of the antenna decreases and attenuation of the atmosphere increases.
A comprise factor is taken while fixing the frequencies and the antenna size. The attenuation factor does not affect the satellites. The bandwidth regulations are taken into consideration while choosing the frequency ranges. The link budget calculations are made so as to check the antenna efficiency and the polarization mismatches.
The attenuation factors does not affect the optical satellite communication and but the reference power may reduce in the receiver antennas. The antenna noise occurs in the satellites or the transmitting antennas due to the unwanted radiation present in the atmosphere. The atmosphere acts as a restiveness medium which supplies the noise power to the antennas present on the earth and also in space satellites.