Satellite Communications (SATCOM)
As described in Chapter 7, long-range communications by reflection of radiowaves from the ionosphere provide communications on a worldwide scale but are limited to frequencies below ~60 MHz. Thus, the bandwidth and the information capacity are severely limited. While shortwave radio broadcasts can be accommodated, television programming would require much more bandwidth.
This limitation has been overcome by placing artificial satellites of the earth in place far above the ionosphere. They are used as reflectors or relay stations in worldwide wireless communication systems that typically operate at frequencies one thousand times larger than the frequencies used in ionospheric reflection systems. We begin ...