Total efficiency dynamics of handheld devices influenced by human hand

The radiation characteristics of small terminal antennas are deteriorated by the presence of the human hand, which influence reveals to be more important than the head. Several hand models and configurations have been compared using the FDTD method, in order to find the amount of absorption and mismatch loss for both monopole and PIFA antennas at 1.8 GHz. It was found a location-dependent behavior of the PIFA on the handset, which affects both absorption loss and detuning. Obtained results confirm that the position of the hand strongly affects radiation efficiency, while absorption loss reveals to be the main issue, being often several dB higher than mismatch loss.