antenna and this seems to absorb more power at 1800MHz than at 900MHz. The SAR

levels in the head are actually lower with the hand than without, despite the peak average

levels shown in the table due to the high SAR in the thumb. Similarly, the temperature

rise at 1800MHz is greater with the hand than without it, but again the peak is in the

thumb. The temperature rise in the head is about 20% less with the hand than without it,

similar to the 900MHz case.

Figure 3: 1g SAR levels (top) and temperature rise (bottom) in the human head at 1800MHz. The

left images are for the head alone. The right images include a hand on the phone and the scales are

adjusted to the peak values of the head-only images. The hand decreases the SAR and temperature

levels in the head and shifts the peaks to the thumb which is located near the antenna feed.

4. Conclusion

The temperature rise in the human head from a cellular telephone appears to be

less when the phone is simulated in the grasp of a realistic hand. While the peak SAR

and temperature rise levels at 1800MHz were greater with the hand than without, the

increase was found to be entirely in the hand while the head levels were actually reduced.

At both frequencies studied, the temperature rise in the head was about 20% less when

the hand was included in the simulation.

Acknowledgement

The authors wish to thank Dr. Christopher Collins of the Center for NMR

Research, Department of Radiology, The Pennsylvania State University College of