By: Saffir Kabir

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One of the newest and most fascinating of the electronic developments in the field of communications is the use of microwaves for transmission purposes.

Microwaves, similar to light waves, travel in a straight line. They do not bend around the earth’s curve; therefore, in order to prevent them from disappearing  out into space, they are beamed from one relay tower to another when use from transmission purposes. A microwave relay beam is of a super high frequency, vibration about four billion times a second. Each electromagnetic wave in the the beam is almost the length of a man’s little finger.

Microwaves are invisible, of course, and as an example of their tremendous ability and versatility, it is worth mentioning that a single radio-relay channel of a microwave beam can carry hundreds of telephone messages simultaneously.

In operation, a microwave radio-relay system works in the following way:

During a telephone call, the message starts out in a normal way by wire or cable to a microwave relay tower. Here a powerful transmitter changes the incoming electrical signals into microwaves. The waves are directed to the top of the tower where antenna reflectors, usually bowl-shaped objects, focus the wave into a narrow beam and flash them through the air to the next relay tower. The towers are usually spaced about 25 or 30 miles apart depending upon their location. They are normally placed on the highest point of a surrounding area. This permits the towers to be separated at the maximum distance.

Each tower is equipped with a set of sending antennas and receiving antennas. They are both alike in form. When the beam strike the receiving antenna, the electrical impulses travel to a powerful amplifying unit where they are given a ten-mellionfold increase in strength so that they may complete the next portion of their transcontinental journey. After its booster shot, the voice-carrying signals, again in the form of a microwave beam, are sent up to the transmitting antenna and flashed through the sky to the next tower. The telephone message follows this procedure more than 100 times till it reaches its destination at the other end of the line.

When the electrical impulses reach the final relay tower, they are changed again from microwaves into voice signal and sent along by wire to a very   complex electronic receiving unit. Here a particular single call is separated from the hundreds of other that travel the same route  and is flashed along wires to the person for whom it is intended. Although the example just describe is for the transmission of a telephone message, the same method holds true for sending television programs across the nation. The only major difference in the latter process is that the microwave beam carries the sound signals as well as the video impulses.

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