How do you deal with SAR problem

Hi
How do you deal with SAR problem ?
Change antenna matching?
or re-design an antenna ?
Thanks.

Most likely by re-desingn of antennas.
More here:
http://ntrg.cs.tcd.ie/mobile/antennas.html

A well-distributed near-field radiation can reduce the SAR.
Sometimes (if the mechanical design allows this) increasing the distance between antenna and human body model (only 1mm or 2 mm) helps to pass SAR requirements.

Hi Vfone
In most of case, it probably fixed antenna location wihtout moving.
In this situation, what's ur suggestion ?
Thanks.

As I said, you have to tune the near-field distribution of the antenna. If is an embedded antenna (PIFA for example) shall be easier to play with this distribution, compared with an external antenna (helix or dipole-derivate).
Just for a quick indication you can do a relative measurement of this distribution, moving a small RF probe all around, at the same distance where the human-body model is located.
Sometimes if is a bad design, the human-body model de-tune the antenna, VSWR is going high, the reflected waves find a different radiation path in the mobile making the SAR test to fail.

In mobile phone case, the location of max current flow on the casing of the phone or the keypad affects SAR greatly, usually PIFA design has lower SAR compare with external design such as Helix, if the head is not exposed to a large amount of radiation then SAR requirement can be met in most cases.