| The problem of the interaction between a human head model and a radio-handset at the frequency of 1900 MHz is studied, both theoretically and experimentally. Our analysis is performed using the method of FDTD. The input impedance and the radiation pattern of the radio-handset in two cases of with and without the head model are calculated, using a simple homogeneous model. The effect of the radio-handset on the head is studied by calculation of the SAR (Specific Absorption Rate) in four different head models, both homogeneous and heterogeneous. A series of measurements on the input impedance and on the radiation pattern of the radio-handset are performed to confirm the theoretical results. Our studies indicate that the effects of the presence of the head model on the antenna model used in our study are a small shift in the centre frequency of the radio-handset, when the head handset distance is around 1.5–2 cm, and a significant shadowing effect on the radiation pattern of the antenna in the direction toward the head. In addition, while the SAR value is not sensitive to the heterogeneity, it reduces by 5% when the neck is added to the model and increases by the same 5% when the size of the head model decreases by 10%. |
