Question about cellular antenna

[Nightwish]

Hi,

I'm sure most of you saw cell phones with a dipole antenna like those:

**broken link removed**
**broken link removed**

These antenna work best when fully opened up to full length. However, they work well even when closed down ( though having much shorter length ). How is it?

Is it a dipole antenna? what's its properties when closed or opened?

:?:

10x for every comment

If you still didn't understand my question than this is what I call an antenna opened up :**broken link removed**

 

[balaguru thavamani]

I think its a helical Antenna

 

[E Kafeman]

Yes it is a helical with dual windings to cover two bands (at least).
Sometimes this type of antenna also have a retractable part such as:
**broken link removed**
When it is extended does it make contact with the helical coil and do then work as a coil loaded monopole and retracted is the monpole isolated from the helical.

 

[balaguru thavamani]

For Dual Band Helical Antenna for Mobile Appications refer to the picture attached