Behavior of Mobile Terminal Antennas near Human Tissue at a Wide Frequency Range

In this paper, the behavior of the impedance bandwidth, SAR and radiation efficiency of mobile terminal antennas are studied by FDTD-based simulations at a wide frequency range, from 0.6 GHz to 6 GHz. The used models comprise a basic coupling element based antenna structure placed beside a simple dielectric block modeling the user. The results of this paper give novel information about the behavior of the bandwidth, SAR and radiation efficiency of mobile terminal antennas near the user. It is shown that even if the resonance frequency changes when dielectric material is brought close to the antenna, the frequency responses of the bandwidth or SAR do not necessarily change accordingly. It is shown also that the locations of the SAR maxima strongly depend on the permittivity of the nearby material. Close relations between the current distribution of the chassis of the antenna and the peak SAR locations are found. The results of this paper give novel information which can be utilized when designing antennas with as low interaction with the user as possible.