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Antennas

Page history last edited by Ben Reyhani 9 years, 3 months ago

What are Antennas?

It is a device that converts electromagnetic waves into electrical currents more specifically it converts radio-frequency (RF) fields into alternating current (AC) or vice-versa.

What categories of Antennas are there?

There are mainly 2 types of wireless antennas:

1. Omni-Directional: are designed to provide coverage in all directions; they RF in a fashion similar to the way a table or floor lamp radiates light. Within this category there are many different types of omni-directional antennas, for example whip antenna, "Rubber Ducky", ground plane antenna, vertically oriented dipole antenna, discone antenna, mast radiator and the horizontal loop antenna are all different types. These antennas are usually used in the field of radio broadcasting and are implemented in devices like cell phones, FM radios, walkie-talkies, Wifi, cordless phones, GPS.

 

                                   

2. Directional: are designed to provide coverage in one or more directions, this allows for increased performance in transmitting and receiving signals which reduces interference from unwanted sources. These antennas radiate RF in a fashion similar to the way a spotlight is designed to focus light on a flag or a sign. Types of directional antennas include: yagi antenna, the log-periodic antenna, and the corner reflector. Directional antennas are usually used in TV antennas, cellular repeaters which give the cellphone greater ranged service then omni-directional antennas and Satelite TV receivers.

 

                                                        

 

Here is a history of the major discoveries of different antennas: 

 

here is an interesting video that shows how to create a television antenna that gives your tv access to different channel s.

 

 

and here is a COOL video that explains how directional antennas work:

 

 

Lastly, check out this video that compares omni-directional antennas and directional antennas

 

 

QUIZ QUESTION:

 

Which type of antenna sends a stronger signal?

 

 

Sources

http://en.wikipedia.org/wiki/Antenna_%28radio%29

http://searchmobilecomputing.techtarget.com/definition/antenna

http://kb.netgear.com/app/answers/detail/a_id/231/~/what-is-an-antenna%3F

http://www.radiolabs.com/Articles/wifi-antenna.html

http://www.wlanantennas.com/wireless_terminology.php

http://www.kyes.com/antenna/antennatypes/antennatypes.html

http://www.usenix.org/event/usenix03/tech/freenix03/full_papers/vandrunen/vandrunen_html/node8.html

http://wiki.answers.com/Q/Types_of_antenna

 

 

 

Comments (1)

J.-P. Brichta said

at 9:58 am on Apr 23, 2011

Nothing here April 23, 11 am.

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