Microwave

Microwave data transmission differs from the previously mentioned communications channels in that data is transmitted through the air instead of through cables or wires. Microwaves are high-frequency radio waves that can only be directed in straight lines. Consequently, microwave transmission is usually limited to communications occurring within the limits of a particular city or community. For microwave transmissions to be able to occur over larger distances, data messages must be relayed from one location to another using antennas placed at high altitudes usually twenty to thirty miles apart.

Instead of antennas, satellites can also be used to transfer microwave messages from one location to another. Satellites rotate approximately 23,300 miles above the earth in precise locations. Satellite transmission stations that can both send and receive messages are known as earth stations. A major advantage of satellite transmission is that large volumes of data can be communicated at once. A particular drawback of several disadvantages is bad weather can severely affect the quality of satellite transmissions. Another one is that it has a serious security problem, because it is easy to intercept the transmission as it travels through the air.

Satellite

Many of these are offered by Intelsat, the International Telecommunications Satellite Consortium, which is owned by 114 governments and forms a worldwide communications system.

Tips

In late 1994, RCA introduced a direct broadcast satellite (DBS) system that enables homeowners or businesses to install 18-inch KU-band VSATs to receive satellite broadcasts for about $700. DBS lets owners receive more than 150 TV channels of higher quality video and audio than traditional cable TV. The real potential for DBS lies not only in the replacement of cable TV, but with the coming integration of video, voice, and data, as another high speed circuit into the home and office.

Ku-band

Ku-band satellites use very short waves that can be caught and concentrated in much smaller dish antennas, called VSAT (Very Small Aperture Terminal), which can be installed on virtually any buildings (or vehicles).