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Ali S.M.,Advanced Technology Research In Motion Ltd | Gu H.,Advanced Technology Research In Motion Ltd
Journal of Electromagnetic Waves and Applications

We present in this paper an approach to control the chassis through electrically extending the length of the ground plane. With this, improved antenna performance in the handset is achieved. The electrical lengthening is made through a nothing approach to the ground plane longitudinal edges. The notches are carefully designed such that they do not interact with the antenna deteriorating its characteristics or radiate causing interference issues. We show the proposed approach through implementation on an internal hexa-band antenna. The improved antenna performance is measured through its bandwidth and efficiency. The performance is examined at two frequencies, 900 MHz and 1880 MHz. An improvement of 22% in the bandwidth at 900 MHz and a 2% improvement at the higher 1880 MHz band are achieved with a similar or a slight improvement in antenna efficiency. The proposed approach is flexible and practical in its implementation and can easily be implemented in the handset to improve the antenna performance, thus, no need to physically enlarge the handset ground plane. © 2011 VSP. Source

Ali S.M.,Advanced Technology Research In Motion Ltd | Mobasher A.,Advanced Technology Research In Motion Ltd | Lusina P.,Advanced Technology Research In Motion Ltd
International Journal of Antennas and Propagation

We investigate in this paper the effects of the user's presence on the performance of a multiple-input multiple-output (MIMO) system in data and in voice usage scenarios. The investigation studies the user effects on the antenna performance and how these are incorporated into the MIMO channel and the link characteristics. The antennas and the user are deterministic. These are then integrated into the statistical 3GPP spatial channel model (SCM) for a typical macrocell propagation environment setting. The channel performance is analyzed based on the average channel capacity, the average power transfer, the correlation, and the cumulative distribution function of the channel capacity as well as the link throughout and the error performance. The mentioned channel and link properties are tied to the MIMO antenna properties that are represented in the mutual coupling between the antennas, the power loss, the total radiated power, the mean effective gain (MEG), as well as the efficiency with emphasis on how the user affects each. It was found that the presence of the user contributed to a loss of up to 50 in the average channel power transfer. The data position was found to be the lowest in terms of channel capacity performance. The voice position performance showed a large dependence on the user orientation with respect to the line of sight path while the data position showed less dependence on the user's orientation. We also discuss through the examined antenna and channel properties the importance of the channel multipath on the MIMO performance. In some scenarios, it was found that a well-conditioned channel can compensate for losses due to the presence of the user, improving the overall system performance. The presented investigation at the link level also discusses the user effects in different MIMO transmission schemes. © 2011 Shirook M. Ali et al. Source

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