Satellites resolved the long-range difficulty of communications. Like a spiders thread, satellites link earth stations to the heavens. Without knowing it, everyday we receive and transmit information by satellite. The life of the satellite depends on the fuel in the initial payload. Each satellite carries a one-time supply of fuel with which to adjust its orbit.
Most satellites are custom made and vary in size depending on the mission and orbit range chosen.
Antenna coverage on the Earth is a function of the antenna pattern and the pointing of the satellite antenna. The coverage must be verified by adding the pointing accuracy of the attitude control system to the calculated antenna pattern. Antennas for receive and transmit bands come in many shapes and sizes. They circle the earth every 90 to 120 minutes. They need to travel at this high rate of speed or would be destroyed by the Earth's gravitational pull.