HFSS human head model and antenna

1)hello I have designed a pifa antennna for 3G and GSM application and human head model in hfss.Can anybody help to give suggestions on measuring SAR in human head model.
2)is there any boundary or excitation to be assigned for human head model to recieve radiation from antenna?

HFSS has features specific for specific absorption analysis. The manual has discussions of what is typically available. If you want to get fancy there is the vector calculator.