Investigations on radiation Q of integrated handset antennas

Today´s small mobile phones offer only a small volume within the casing for the integration of the antenna. Therefore, the design of integrated handset antennas is a complex process, that has to be done with respect to the strong interaction between antenna and the other components of the mobile phone. Because of the small space available, the antenna dimensions typically have to be reduced by using high permittivity materials or by folding the antenna structure. Both mechanisms lead to a significant reduction of bandwidth that is the most critical parameter in the design process. Former investigations show, that the bandwidth of integrated handset antennas depend not only on the size and the shape of the antenna itself, but also on the size and the orientation of the handset PCB (see Geissler, M. et al., AP 2000 Millennium Conference, 2000). These former results have now been taken as a basis for the next step of the investigation, that analyze the nearfield properties of the different configurations. The results show that the bandwidth and the radiation Q of handset antennas can be related to the structure of the nearfield in the vicinity of the phone. Furthermore, these results may help in learning more about the fundamental limitations of the radiation Q in the special case of integrated handset antennas.