User:Farideh.soheily

Television signals cross a continent by relay towers,which pick up and amplify the straight_line microwave beams.but there is no way to build towers on water,and signal sent across the sea could not follow the curve of the earth.Its straight_line beam would soar off in to space scientists have solved this problem by designing a new kind of tower,a tower in the sky_asatellite.An active satellite contains amplifiers much like those in the over land microwave tower.When a microwave is beamed to it form a ground transmitter, the satellite increases strength of the signal and reflects it to ground receiving station beyond the curve of the globe. Technologists know enough today to place a satellite system in medium_range altitudes from about5000 to 8000 miles in spaceAsystem of about fifty satellites would provide many circuits which would cover the present communication needs of the world.