Antenna (Encyclopedia of Science)
An antenna is a device used to transmit and receive electromagnetic waves, such as radio waves and microwaves. Antennas are found in a great variety of communication devices, including radios and television sets, weather radar systems, satellite communications systems, and radio astronomy research centers.
Your local radio station uses an antenna to transmit the programs it broadcasts. Words that are spoken or music that is played within the station are converted to electrical signals. These signals are then transmitted to an antenna in the form of an electric current. Electrons inside the antenna vibrate back and forth with the same frequency as the incoming
electric current. The vibration is characteristic of the sounds produced within the station. As these electrons vibrate, they create an electromagnetic wave in the air around the antenna. That wave spreads out and travels in all directions from the antenna. The frequency of the wave is the same as the frequency of the electron vibration in the antenna and of the sounds spoken in the...
(The entire section is 297 words.)
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