Microwave and Radio-Based System

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.

Microwaves (the actual radio waves) are between 1 mm and 30 cm long, and operate in a

frequency range from 300 MHz to 300 GHz. Microwaves were first used in the 1930s, when British

scientists discovered the application in a new technology called radar.

Today's microwave radios can be installed quickly and relocated easily. The major time delays are

usually in getting through the regulatory process in a governmentally controlled environment.

Several installations have taken over a year to be approved, only to have the radio system installed

and running within a day or two. In many situations, microwave systems provide more reliable

service than landlines, which are vulnerable to everything including flooding, rodent damage,

backhoe cuts, and vandalism. Using a radio system, a developing country without a wired

communications infrastructure can install a leading−edge telecommunications system within a

matter of months. For these reasons, regions with rugged terrain or without any copper landline

backbone in place find it easier to leap into the wireless age and provide the infrastructure at a

fraction of the cost of installing wires.

Microwave also played a very crucial part of the PCS industry as the PCS systems use the 1.9 to

2.3 GHz frequency band. Fixed systems operators such as police, fire, electric utilities, and some

municipal organization occupied these frequencies. To accommodate the move of these users from

the 2 GHz frequency band, microwave was used to relocate the users to a new band, as mandated

by the FCC. One study indicated that the PCS industry would spend over $3 billion in microwave

equipment and services by 2005.