What Causes Antennas to Radiate?

[shankar]

what makes antenna to radiate,the basic principle...

 

[chroot]

You pass radio-frequency alternating currents through the antenna. The electrons in the antenna get jostled back and forth. Jostling electrons create jostling electromagnetic fields. Jostling electromagnetic fields are what we call "radio waves."

- Warren

 

[Integral]

Currents induced in the antenna by the transimtter, produce a Electro magnetic field. This is all coverd by Maxwells equations. Due a web search on that key word for more information.

 

[shankar]

the alternating current produce fiels...then what about the induction principle...where electric field produce only magnetic field no radio waves?
[?]

 

[chroot]

Originally posted by shankar
the alternating current produce fiels...then what about the induction principle...where electric field produce only magnetic field no radio waves?
[?]

Changing electric fields create magnetic fields. Changing magnetic fields create electric fields. You cannot jostle an electron around without producing SOME radiation.

- Warren

 

[McQueen]

Originally posted by chroot
You pass radio-frequency alternating currents through the antenna. The electrons in the antenna get jostled back and forth. Jostling electrons create jostling electromagnetic fields. Jostling electromagnetic fields are what we call "radio waves."

- Warren

To elaborate , electrons jostle against ions which are held in a fixed position in the crystal lattice of the conductor , causing the ions to vibrate and produce electric fields.

 

[shankar]

ya its true E&M are there but at what condition they the element radiates field?

 

[chroot]

Originally posted by shankar
ya its true E&M are there but at what condition they the element radiates field?

What?

- Warren

 

[Integral]

Originally posted by McQueen
To elaborate , electrons jostle against ions which are held in a fixed position in the crystal lattice of the conductor , causing the ions to vibrate and produce electric fields.

Ionic motion is not needed, electron motion alone will do the trick. In fact any ion vibration will probably be in the infra red energy region.