How Radio Antennas Work

Radio antennas can be seen every where from our cars to the tops of TV's to large radio telescopes.  All of these many antennas have the same purpose to send and or receive electromagnetic radiation or radio waves.  Before the methods used to do this can be discussed the electromagnetic wave needs to be clear to the reader.  Electromagnetic Waves.

  Typical car antenna (From: http://www.cometantenna.com/mobile.html)

  Stationary Ground wave antenna (from: http://www.cometantenna.com/cfm95sl.html)

Receiving antenna of the Arecibo Radio Telescope in Puerto Rico
(http://www.naic.edu/vpublic/vcenter/aovef.htm)   This is the Radio Telescope used by The seti project to try to find signals from outer space.