In this thesis, we propose a new bandwidth-enhancement method of using a parasitic open slot to achieve a wide lower band for the internal laptop computer antenna with a small size to cover the GSM850/900 operation and a wide upper band to cover the GSM1800/1900/UMTS operation as well. The occupied antenna volume is only 48 ¡Ñ 10 ¡Ñ 3.5 mm^3 above the top edge of the display ground. For practical application, we analyze the effects of the antenna position, nearby metal plate, shielding metal plate, keyboard ground, FR4 substrate, and the size of display ground on the performance of the WWAN antenna. In addition, effects of the user¡¦s whole-body on the proposed antenna are also analyzed. Owing to the user¡¦s whole-body being mainly lossy materials, a decrease in the antenna¡¦s radiation efficiency is observed when the user¡¦s whole-body is in close proximity to the WWAN laptop computer antenna.

For applications of wireless communication of the fourth generation (4G LTE), the technique of using a printed parallel-resonant spiral strip for bandwidth enhancement of a small-size planar laptop computer (especially the thin Ultrabook) antenna for the LTE operation is first presented. The antenna is printed on a thin FR4 substrate of small size 45 x 9 mm2 with a simple uniplanar structure which is promising for Ultrabook application. Based on the proposed antenna structure, its application for MIMO operation to achieve enhanced isolation is also analyzed in this thesis. Different from the works for the relatively much smaller ground plane conditions such as in the mobile phones, the effect of different size of the supporting conductive plate of the upper corner of the Ultrabook is discussed for the isolation issue of the MIMO antennas. Finally, the technique of isolation improvement in the LTE700 band for the MIMO operation in the Ultrabook is presented.

Two novel internal WWAN antennas having multi-band operation capability and suitable to be embedded in the laptop computers are proposed. The first antenna is a penta-band printed monopole slot antenna, which can cover GSM850/900/1800/1900/UMTS operation. The second antenna is a penta-band printed dual-loop antenna. The antenna can cover GSM850/900/1800/1900/UMTS operation and occupies a small size. The effects of the environment and the user¡¦s hand on the internal laptop computer antenna are also studied. Take the first antenna as an example; the obtained results show that the effects of the internal environment of the laptop computer are mostly on the antenna¡¦s impedance matching, which however can be improved by adjusting the parameters of the antenna. On the other hand, since the user¡¦s hands are lossy materials, a decrease in the antenna¡¦s radiation efficiency is observed when the user¡¦s hand is in the vicinity of the internal antenna.