ARRAYPARASITIC

PARASITIC ARRAY consists of one or more parasitic elements with a driven element, the amount of power gain and

directivity depends on the lengths of the parasitic elements and the spacing between them

THINKOF ITTHISWAY

How can this small light bulb illuminate a large room if this

said bulb is placed in the center?

Of course you need

REFLECTORS

However, if a reflector were placed behind the bulb, the space in front of the reflector would be brighter

and the space behind the reflector would be dimmer.

But, WAIT you can also direct the light to where you wanted to place it using

LENS or what we known as DIRECTORS.

Thus, the combination of light bulb, reflector and lens can be summed up

to a

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How is a flashlight comparable to a parasitic antenna?

PARTS

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• LENS• BULB• REFLECTOR

• Parasitic elements

• Driven elements

When the parasitic element is placed so that it radiates away

from the driven element, the element is a director. When the

parasitic element is placed so that it radiates toward the driven

element, the parasitic element is a reflector.

OPERATION

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Although we do not usually discuss the gain of a flashlight, we can continue the comparison of an antenna and a flashlight to explain the meaning of antenna gain. Suppose the spot on the wall in front of the flashlight becomes 10 times brighter than it was when only the open bulb was used. The lens and reflector have then produced a 10-fold gain in light. For antennas, the simple half-wave antenna corresponds to the open bulb in the flashlight. Suppose an antenna system concentrates the radio

waves so that at a particular point the field strength is 10 times more than it would be at the same distance from a half-wave

antenna. The antenna system is then said to have a gain of 10.

RAD PATTERN

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UNIDIRECTIONAL UNIDIRECTIONAL

Is it possible to change the radiation pattern of a parasitic array antenna?

YES OFCOURSEHOW??????????????????????????

Changing the spacing and length can change the radiation pattern so that

maximum radiation is on the same side of the driven element as the parasitic

element.

Finally, its easier to remember properties and parts of a flashlight than the parasitic array antenna. Thus, given all the

specifications, a flashlight is comparable to a parasitic antenna