Question

1. What are communication satellites.?

(b) State and write about the three (3) types of communication satellites you have

studied and the zones they occupy in space.

Answer 1

Answer:

1.

Communication satellites are artificial satellites that act as a large repeater in the sky. It functions by receiving signal via source transmitter, amplifies using the transponder and relays them to the receiver, thereby creating a communication channel between the earth’s location that would not have been able to communicate due to long distance or obstruction caused by earth’s curvature.

(b)

The three types of communication satellites are segregated on the basis of orbits (zones) in which they are placed.

1. Geostationary Satellite (GEO): They are placed at a height of 36,000 km from the earth’s surface. Their orbital period is same as of earth’s rotation. Hence, appears to be still in the sky. At least 3 GEOs are need for complete global coverage.

2. Medium Earth Orbit Satellite (MEO): These satellites are placed between the two Van Allen belts, at a distance between 2,000 km to 36,000 km from the earth’s surface. At least 10 MEOs are need for complete global coverage. Because their position above the earth’s surface is not enough to capture large surface area of earth. Lesser the distance from the earth’s surface, more the number of satellites needed.

3. Low Earth Orbit Satellite (LEO): These satellites are situated below the lower Van Allen belt. Their orbital altitude is 160 km to 2000 km. For global coverage as high as 50 LEOs are needed. As we discussed above lesser the distance from earth’s surface, more the number of satellites needed due to limited coverage.