Mimicking Gel or liquid for human tissue

Hi, I would like to test the performance of the MICS band (403MHz) implantable antenna.
Is there a ready made/off the shelf mimicking gel or some liquid which has the same electrical properties as human tissue?
Any manufacturer or supplier that I can look for?

Thanks

Some european company sell that, it's very expensive.

The muscle equivalent phantoms[6] are made out of a molten mass consisting of agar, sodium chloride, preservatives and deionised water,

http://www.bioline.org.br/request?cr05036