Accurate and efficient models of the human hand for the prediction of antenna efficiency in mobile devices

Abstract

The antennas in a mobile device, like a cellular phone, are significantly impacted by the presence of the user, especially in the talk position. Traditionally, this impact has not been accurately modeled and, in many cases, it is completely ignored. This results in an inaccurate prediction of the antenna performance, especially the radiation efficiency, and can lead to poor antenna design. In this article, the modeling of the hand in greater detail is considered. Although many CAD tools have the capability to model the hand geometry in fine detail with multiple materials, there are associated issues dealing with the model complexity and constructing hand phantoms for measurements. Therefore, a balance needs to be reached between the details in the model geometry and materials and the needs of the simulation and measurement tools. In this paper, a homogeneous hand model is presented. The model represents the geometry of the hand in good detail and it can be adapted to form various hand grips. The effect of the material properties of this hand model on the radiation efficiency of a few typical antennas in mobile handsets is studied. These studies illustrate than an effective material property for a homogeneous hand model can be used for a reasonable accuracy in the radiation efficiency of the antennas. A two tissue model consisting of bone and muscle is also studied.