SAR Adjustment Problems

dear friends
I'm working on SAR reduction subject and I want to reduce the SAR parameter in an antenna project.
As you know, because the SAR is proportional to the Electric field in order to adjust the SAR I can
distribute Electric field uniformly and correctly, so
how can I adjust the Electric field to obtain lower or uniformer SAR distribution?
I found some useful methods to do this such as change the structure of the antenna
but I want to fulfill it profoundly,not by trial and error method.
do you have any idea , refrences or any usefull subjects to do it?

It would seem that you have a few options: decrease the power transmitted (by increasing antenna efficiency if possible), change the medium surrounding the antenna (highest SAR in general) with a lower loss material, or both ;)

Have Fun

dear tallface65
u are right
by decreasing the deliver power of excitation feeding we can adjust the SAR distribution in order to satisfy the ANSI SAR standards.
but I actually need to decrease the SAR level with 1W deliver power of feeding.
Assume that the deliver power is 1 W and the spatial SAR is 8 mw/g I want to use some method to decrease this value to 6 mW/g.
In fact the SAR standard limitation is 1.6 mW/g so it's better to decrease the 8 mW/g to 1.6 mW/g but actually with 1 W deliver power it is not possible.
Although this reduction from 8 mW/g to 6 mW/g is not enough but it's better than nothing.;)
one method is changing in the antennas structure (i.e by changing the structure in some point of antenna that the Electric fields are more intense it lead to adjust the SAR distribution)
but what's the other methods?
I know there are some other methods such as shielding the antenna by ferrite materials to do this but I want to inspect this subject profoundly not by trial and error.
what's your idea?
how we can control Electric field or SAR distribution in an antenna?

What is the medium which is absorbing the power? A human body, air? Is the antenna surrounded by the absorbing medium, or is it a certain size/distance relative to the antenna?

In any case, I don't think I will be able to give a specific answer. However, I would highly recommend looking over research papers about SAR in high field (like 7 tesla and above) magnetic resonance imaging (MRI). Tremendous effort has been given to reducing SAR there, since it's a major safety issue, and people have developed some pretty incredible techniques, including phased coil/antenna arrays, use of dielectric materials, etc. I bet you'll get some good ideas, at least.

Dear mtwieg
thanks for your reply
the medium is a human body and the antenna is surrounded by the human tissue.
I read many useful paper in this subject (i.e SAR reduction in human body) and I found by some changing in antenna structure
the researchers could modify the Electric field distribution and then improved the spatial SAR distribution.
there are different methods to change the antenna structure like using segmented patch,shield material around the antenna and even using metamaterial in the structure of this antenna(I mean implanted antennas)
but my first question is this:
first,I want to change the Electric field distribution by attention to the fundamental electromagnetic equations (i.e Maxwell equations).