Antennas used in new cellular phones & USB modems

[somf0872]

Experts,

Any idea what type of antenna being used in latest cellular phones & USB modems. I mean now a days, vendor claim that the new generation USB modem can support GSM/3G/LTE on the band 700/900/1800/2100/2300/2600. How is it possible that antenna can support all the bands with just miniature size. Usually lower the frequency band, larger the antennas size. Isn't it?

One example is
**broken link removed**

Regards,
Faisal

 

[eagle5]

These antennas are usually of PIFA architecture (Planar Inverted F-Antenna).
The length of the antenna is a quarter-wavelength. At GSM-900 that means about 8cm.
Aditionally these antennas are folded to occupy less space (see the figure attached). By combining multiple foldings and metallic sections, multiple resonances are achieved. The design process is quite complex.
I remember splitting my old phone appart to look at the antenna. It occupied an area of barely 3cm by 2cm.