We investigate the penetration of electromagnetic fields caused by a cellular phone into a human head using the Finite Integration Technique in time-domain. The applied human head model is created directly from NMR data and consists of 500 000, respectively 4 million mesh cells. The final calculation domain is set up by 1.8 million cells, corresponding to 10.8 million unknowns for the electrical field and magnetic flux. With a broadband stimulation of the monopol antenna we calculate the frequency response inside the human eye over a frequency range of 300MHz up to 1.8GHz considering the dispersion of the biological tissues. Finally the farfield pattern of a hand-held device placed in the vicinity of the human head are investigated.