Studies of the optimum isolation in a multi-mode PDA phone are presented in this thesis. Firstly, we analyze the optimum isolation between the DCS and GPS antennas embedded in a dual-mode PDA phone. Then, we change the antenna types of the DCS system to study again the behavior of the optimum isolation. Secondly, we analyze the optimum isolation between a DCS antenna and a WLAN antenna embedded in a dual-mode PDA phone. Finally, we propose a multi-mode PDA phone for DCS, GPS, and WLAN operations with good isolation among the three internal antennas.

No / This study presents a miniaturised multiple input and multiple output /diversity antenna which is suitable for high data-rate communication systems such as mobile ultra-wideband (UWB). This antenna assembly comprises two identical planar inverted-F antennas, a T-shaped structure connecting them and a finite ground plane. The T-shaped structure improves the impedance matching and suppresses the mutual coupling between the antenna elements over a wider bandwidth than previously reported. The compact envelope dimension of this antenna is 50 x 90 x 7.5 mm(3). Theoretical and experimental S-parameters are illustrated for this antenna that fully cover the UWB operating frequency band of 3.1-10.6 GHz, with a reflection coefficient and mutual coupling better than -10 and -20 dB, respectively. Acceptable agreement is obtained between computed and measured radiation patterns, gains, envelope correlation coefficient and channel capacity loss. The proposed antenna is an attractive candidate to provide pattern diversity and enhance channel capacity in a rich scattering environment.

No / This article presents a printed crescent-shaped monopole MIMO diversity antenna for wireless communications. The port-to-port isolation is increased by introducing an I-shaped conductor symmetrically between the two antenna elements and shaping the ground plane. Both the computed and experimental results confirm that the antenna possesses a wide impedance bandwidth of 54.5% across 1.6-2.8 GHz, with a reflection coefficient and mutual coupling better than -10 and -14 dB, respectively. By further validating the simulated and the measured radiation and MIMO characteristics including far-field, gain, envelope correlation and channel capacity loss, the results show that the antenna can offer effective MIMO/diversity operation to alleviate multipath environments.