Microwave and Radio Based System

         Many people have just taken for granted the importance of microwave communication. Microwave communication is very important in our daily lives. It is used for communication in great distances about a several hundred miles away. It is used in voice communication, television broadcasting, data communication and others. Microwave system suppliers have a great market on microwave communication systems. On point to point microwave radios services the suppliers have reached the sum of $4 billion of their products in 2006. 

          Microwaves have a wavelength of 1mm and 30cm long and has an operating frequency of 300 MHz to 300Ghz. Microwave was first used on the year 1930. A microwave was first discovered on World War II when two scientists invented the Magnetron which produces microwaves. It is used in Britain’s radar system to detect incoming war planes.  Microwave radio was used on 1950 for long distance voice communication. Bulky vacuum tubes were used and 2,100 watts is needed for the system to operate. But now with the help of the transistors and IC’s all has been in compact into a smaller device and much more reliable device. Microwave systems are more reliable than telephone landlines because it cannot be flooded away or no wires can be damage by animals or other means of nature. 

Here is an image of a cellular microwave radio:

           When a microwave system is transmitting on more than 40 miles a repeater is needed for the signal to reach the receiver. Repeaters are composed of a receiver and a transmitter just like a transceiver.  A repeater receives a signal then amplifies it and then reshapes the signal for transmitting into another repeater or to receiving station.

           Most television system and radio companies are using microwave systems. On television companies they use satellites for repeaters to broadcast into other countries or distant places. Another is the news station, when taking actual news on the streets the camera is connected to a van that has a portable microwave system and transmits the video via microwave to the base station to the TV news room.

          

Advantages of Microwave Radio:

1.    Radio systems do not require a right of way acquisition between stations.

2.    Each station requires the purchase or lease of only a small area of land.

3.    Because of their high operating frequencies, microwave radio systems can carry large quantities of information.

4.    High frequencies mean short wavelengths, which require relatively small antennas.

5.    Radio signals are more easily propagated around physical obstacles such as water and high mountains.

6.    Fewer repeaters are necessary for amplification.

7.    Underground facilities are minimized.

8.    Minimum delay times are introduced. Minimal crosstalk exists between voice channels.

9.    Increased reliability and less maintenance are important factors.

Disadvantages of Microwave Radio:

1.    It is more difficult to analyze and design circuits at microwave frequencies.

2.    Measuring techniques are more difficult to perfect and implement at microwave frequencies.

3.    It is difficult to implement conventional circuit components at microwave frequencies like resistors, capacitors, inductors, and so on).

4.    Transient time is more critical at microwave frequencies.

5.    It is often necessary to use specialized components for microwave frequencies.

6.    Microwave frequencies propagate in a straight line, which limits their use to line of sight applications.

Here are some pictures of an old microwave system that was used in World War II:

Sources: 

• Broadband Telecommunications Handbook, Second Edition by Regis J. Bates
• Electronic Communication Systems by Wayne Tomasi
• http://www.smecc.org/arnold_acker.htm
• http://bigdesignevents.com/2011/09/innovations-from-world-war-ii/