Characterisation of Multiple Antennas and Channel for Small Mobile Terminals

MIMO (Multiple Input Multiple Output) technology has been regarded as a practical approach to increase the wireless channel capacity and reliability. In this technology, the performance of multiple antennas has a significant effect on the MIMO channel capacity. Currently, the MIMO channel capacity is mostly evaluated without accounting for the practical aspects of multiple antennas. Though multiple antennas have been considered in a number of studies, only dipole or monopole antennas were used to evaluate the channel capacity. Practically, multiple dipoles and monopoles are no longer used for small mobile terminals because of their high profile and poor isolation performance. Implementing multiple antennas on a small mobile terminal remains a major engineering challenge. The objectives of this thesis are to design practical antenna arrays for small mobile terminals running MIMO applications, and to obtain the corresponding channel characteristics in a realistic environment. The research is conducted in the following areas. A novel PIFA (Planar Inverted-F Antenna) design and its array are proposed and studied. The single PIFA with a small ground plane constitutes a stand-alone structure. The ground plane, as small as the antenna, is located between the PIFA and the PCB (Printed Circuit Board) so that the PCB is no longer acting as a ground plane for the PIFA. The two PIFAs mounted on the PCB do not share the same ground plane. Consequently, the isolation performance between the two modified PIFAs is significantly improved. The characteristics of both single-element and dual-element PIFA in the 5.2GHz and 2.5GHz frequency bands are evaluated in simulation and measurement. Following the study of multiple antennas, the concept of antenna diversity technology was introduced into the Galileo navigation system for the first time in the GAC (Galileo