MULTI-BAND BALANCED ANTENNAS WITH ENHANCED STABILITY AND PERFORMANCE FOR MOBILE HANDSETS

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The move toward worldwide wireless communication continues at remarkable pace, and the antenna element of the technology is crucial to its success. Various mobile antenna structures have found increasing attention, significant characteristics being small size and low cost. However, the characteristics also need to be optimised with respect to the antenna radiation patterns and the Specific Absorption Rate (SAR) levels for compliance with international safety guidelines. Moreover, the antenna should have weak coupling with the body of the handset to provide the best performance stability and impedance matching in the presence of a human body, including the hand holding the handset. A good candidate is to use balanced antennas to reduce the effect of the mobile antenna on the handset, since unbalanced antennas drive current into the handset chassis, which interacts strongly with the unpredictable characterisitics of the body. The maximum specific absorption rate (SAR) values have been shown to be substantially reduced when placed next to the human head, compared with conventional unbalanced antennas, if these antennas are well-designed. The purpose of the study will be to design an antenna that will be developed using the Bradford hybrid electromagnetic modelling technique, allied to genetic algorithms to optimise the enhancement of the bandwidth. Multiple-band and wideband variants of these antennas for 2G, 3G, B3G and IEEE 802.x mobile bands will also be considered as a key target of the project.