3. Explain the advantages and disadvantages of Microwaves.

Thursday, 6 February 2014

3. Explain the advantages and disadvantages of Microwaves.

Advantages of Microwaves:

Microwave frequencies are extremely high.Hence they offer extremely high Bandwidth for communication channels. For example, a typical microwave communication channel can carry 4000 audio or 4 video channels. Only, optical communication channels have more Bandwidth than this.

They propagate along line-of-sight paths through troposphere, where loses that we face in the ground-wave and sky-wave propagations are absent or minimum. Therefore, for transmission of signals, the transmitter power used will be much smaller than that required in the cases of the ground-wave and the sky-wave propagations. (With microwave frequencies, even a 100W transmitter is considered as a high power transmitter.)

Antennas required at microwave frequencies are much smaller in size than those used at lower frequencies. Because of this, and because of the low losses, microwave frequencies are used in modern mobile communications system.

Usually, noise interference from disturbances such as automobile ignition switches will not affect microwaves as they occur at much lower frequencies.

Microwave communication is a point-to-point communication scheme through cables or antennas. Hence, tapping is difficult at these frequencies as they require highly specialized and costly equipments for carrying out those tasks.

Microwave tend to flow through the surface of conductors due to what is known as skin effect. This in turn has been effectively used in a heating process called induction heating. Induction heaters are being widely used in the manufacturing of blades, knives, semiconductor chips etc.

Since microwaves are also AC, they can flow through capacitors, microwave frequencies heat up the dielectric material in between the capacitor plates. This type of heating is called the dielectric heating. This is the principle of operation of modern microwave ovens.

Disadvantages of Microwaves:

A major disadvantage of microwaves is the nature of propagation itself. As has been seen, microwaves propagate in the line-of-sight mode. In this mode, microwave frequencies travel in straight-line paths, Which are limited by the horizon. The maximum range of transmission, hence, is limited to a radius of 80 km around a transmitter. For long distance transmission, we must use repeating stations at approximately 80 km interval.

Microwave transmission towers are complex in construction, and are highly expensive.


Post a Comment