Measurement techniques for characterising antennas of hand-held mobile telephones considering the user's influence

摘要

Input impedance, radiation patterns and efficiency (the latter to be derived from the power budget) are essential parameters characterising an antenna. When investigating antennas of hand-held mobile telephones, consideration of the user's influence on these parameters is indispensable. For the development of new concepts (with the aim of optimisation of hand-held transceiver antennas in such a way that interaction with the human body becomes a minimum) numerical calculations are often the first step with the design of the antenna to be followed by a validation through measurements. The authors discuss the criteria for EMC investigations, double cone near-field scanning, multiple probe near-field scanning, power budget, absorption rate and antenna efficiency, and measurements with head phantom and GSM sets. Hand-held transceivers with monopole antennas of both GSM and DCS-1800 system cause absorption factors of up to 70% in a worst case situation, where the antenna is held upright and close to the human head. The investigations were carried out by both measurement and numerical calculation showing good agreement in the achieved results.