KIVEKÄS et al.: BANDWIDTH, SAR, AND EFFICIENCY OF INTERNAL MOBILE PHONE ANTENNAS

85

several differences between the studied prototypes and commer-

ciency occur compared to the general trend. Thus, it can be con-

cial products. However, values of the same order as in this paper

cluded that when reporting any SAR or efficiency values of mo-

have been presented in [6] for similar prototype structures. This

bile phone antennas, it is essential to give information also on

study also demonstrates that the worst case SAR values in the

the impedance bandwidth.

head are obtained without hand. The SAR values in the hand

models used in this work are clearly lower than the specified

ACKNOWLEDGMENT

maximum value 4.0 W/kg averaged over 10 g of tissue [18],

[28]. However, the study shows that concerning the efficiency

The authors wish to thank Dr. C. Icheln for his help in the

of the antenna-chassis combination, it is necessary to consider

radiation efficiency measurements and for his kind assistance

also the effect of the hand, as the decrease in efficiency due to the

with the simulators.

hand may be several decibels depending on the configuration.

The presented results also indicate that the type of the used

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