Effect of the User's Hands on the Operation of Lower UHF-Band Mobile Terminal Antennas: Focus on Digital Television Receiver

This paper deals with the effect of the user´s hands on the performance of lower UHF-band antennas in handheld terminals. It is studied that how the input impedance, efficiency, and far-field directional pattern of the internal broadband digital television antenna are affected by the presence of the user´s hands. The main part of the study has been carried out by applying finite-difference time-domain simulations. Measurements have been performed to support the results obtained by simulations. In the worst case, as much as 7-11 dB decrease of the antenna efficiency compared to free space case is shown. The results also indicate that the power absorption to the hand(s) is generally a more severe problem for the total efficiency than the change of the matching. On the other hand, it is also shown that in certain cases, the total efficiency of the antenna can even be improved due to the hands of the user. The results of this paper increase the understanding of the effect of the user´s hands on the operation of the lower UHF-band antennas, whose operation is based on the radiation of a finite ground plane.