Microwave transmission is the transmission of information by microwave radio waves. Although an experimental 40-mile (64 km) microwave telecommunication link across the English Channel was demonstrated in 1931, the development of radar in World War II provided the technology for practical exploitation of microwave communication.
Microwaves are widely used for point-to-point communications because their small wavelength allows conveniently-sized antennas to direct them in narrow beams, which can be pointed directly at the receiving antenna. This allows nearby microwave equipment to use the same frequencies without interfering with each other, as lower frequency radio waves do. Another advantage is that the high frequency of microwaves gives the microwave band a very large information-carrying capacity; the microwave band has a bandwidth 30 times that of all the rest of the radio spectrum below it. A disadvantage is that microwaves are limited to line of sight propagation; they cannot pass around hills or mountains as lower frequency radio waves can.
Microwave radio transmission is commonly used in point-to-point communication systems on the surface of the Earth, in satellite communications, and in deep space radio communications. Other parts of the microwave radio band are used for radars, radio navigation systems, sensor systems, and radio astronomy.
Properties of microwave links
- Involve line of sight (LOS) communication technology
- Affected greatly by environmental constraints, including rain fade
- Have very limited penetration capabilities through obstacles such as hills, buildings and trees
- Sensitive to high pollen count
- Signals can be degraded during Solar proton events
Uses of microwave links
- In communications between satellites and base stations
- As backbone carriers for cellular systems
- In short-range indoor communications
- Linking remote and regional telephone exchanges to larger (main) exchanges without the need for copper/optical fibre lines
- Measuring the intensity of rain between two locations