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.

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.

A mobile phone antenna with a radiating coupling feed is presented. By using the radiating coupling feed, the conventional coupled-fed loop antenna and coupled-fed shorted monopole antenna can be efficiently incorporated into the antenna structure and respectively excite a wide band resonant mode to cover GSM850/900 and GSM1800/1900/UMTS/LTE2300/2500 for the seven-band operation. Besides, the antenna can be in compact integration with the extended ground plane such that more electronic components in the mobile phone can be accommodated in the practical applications. In order to study the near-field radiation characteristics of the antenna, SAR and HAC are also simulated and analyzed.

An internal eight-band LTE/WWAN handset antenna integrated with a USB connector is presented. The proposed antenna comprises an antenna ground which faces a protruded ground extended from the main ground of the handset to accommodate a USB connector. The antenna ground is used as a shorting portion to short-circuit the antenna to ground such that the coupling between the antenna ground and the protruded ground is effectively suppressed. In this case, the proposed antenna can be integrated with a USB connector mounted on the protruded ground, leading to compact integration of the antenna inside the handset. Good radiation characteristics of the antenna are also obtained, and the proposed antenna occupies 60 ¡Ñ 12 ¡Ñ 4.8 mm3 (about 3.4 cm3) only. Effects of the user¡¦s head and hand on the proposed antenna are studied, and the simulated SAR and HAC results are also analyzed in this thesis.

In this thesis, two types of handset antenna design respectively for dual-band GSM850/1900 operation and seven¡Vband LTE/WWAN operation are presented. The proposed antennas can achieve decreased antenna size and enhanced operating bandwidth by shaping the system ground plane of the handset. The seven-band LTE/WWAN antenna is printed on the system circuit board with good radiation characteristics and occupies a small size of 24.5 x 10 mm2. At first, we propose a half-loop antenna structure which integrates its facing edge of the system ground plane as the resonant path of the antenna. In this case, the required length of the half-loop antenna structure is only about a half compared with the traditional loop antenna. Next, to enhance the operating bandwidth of the antenna, a parasitic shorted monopole strip is added and a shaped system circuit board is used. The shaped system circuit board can integrate the battery with the circuit board to help reduce the thickness of handset. Also, much enhanced operating bandwidth for the lower band can be obtained, owing to the enhanced surface current excitation in the system ground plane resulting from properly shaping the system circuit board. Effects of the user¡¦s head and hand on the proposed antenna are studied, and the simulated SAR and HAC results are also analyzed for bio-compatibility issue.

In this dissertation, novel printed multiband antennas for slim mobile communication devices are presented. The design techniques on achieving decreased antenna size and enhanced operating bandwidth in different shaped system ground planes with the antennas printed thereon are proposed. At first, a WWAN antenna integrated with a U-shaped ground plane is presented. Two techniques are applied to achieve WWAN operation with a small antenna size. The first technique is to embed load a proper chip inductor at a proper position in the shorted strip monopole of the antenna. The second one is to use a band-stop matching circuit disposed on the main circuit board of the handset. For the second and third antenna designs, owing to the C-shaped ground plane, much enhanced operating bandwidth for their lower band can be obtained. The second antenna design can cover the LTE/WWAN eight-band operation without increasing the size of the antenna by using a reconfigurable circuit element. The third antenna design integrated with a battery element and a metal midplate for practical application to help reduce the thickness and enhance the robustness of handset. The antenna can cover seven-band LTE/WWAN operation with good radiation characteristics and occupy a small size of 35 x 8 mm2. Finally, the simulated SAR and HAC results are analyzed for bio-compatibility consideration.

In this thesis, an internal mobile phone antenna with a distributed matching circuit for eight-band LTE/WWAN operation is presented. By selecting proper dimensions of the distributed matching circuit, the bandwidth of the proposed antenna can be greatly enhanced. Good radiation characteristics are also obtained, and the proposed antenna occupies only 60 ¡Ñ 10 ¡Ñ 3 mm^3 and is very suitable for slim mobile phone applications. Effects of the human body including user¡¦s head and hand are also studied, and the SAR and HAC issues are simulated and analyzed in this thesis.

A tablet computer antenna array for WWAN/LTE and LTE MIMO operations is proposed. The antenna array comprises a main antenna and an auxiliary antenna. The main antenna is an eight-band coupled-fed antenna, which can cover the GSM850/900/1800/1900/UMTS and LTE700/2300/2700 operations. The auxiliary antenna is a three-band antenna, which can cover the LTE700/2300/2500 operation and occupies a small size. Acceptable isolation between the main and auxiliary antennas has also been obtained, which makes it promising for the main and auxiliary antennas to perform LTE MIMO operation in the LTE700/2300/2500 bands. Effects of the internal tablet computer antenna on the user¡¦s body are also studied. The obtained results show that the antenna can meet the 1-g body SAR specification of less than 1.6 W/kg by selecting a proper distance between the antenna and the flat phantom. Also, since the user¡¦s body is a lossy material, a decrease in the antenna¡¦s radiation efficiency is observed when the user¡¦s body is in the vicinity of the internal antenna.

Bandwidth enhancement of the LTE/WWAN handset antenna achieved by improving the excited surface current distribution in the system ground plane is presented. To achieve this goal, the system ground plane is shaped to be of a C-shape in this thesis. In this case, the longitudinal excited surface current in the system ground plane can have a smooth distribution. The proposed antenna is disposed at one edge of the C-shaped system ground plane, and the antenna comprises a driven monopole strip, a shorted monopole strip and a distributed parallel resonance (PR) circuit. By controlling the resonant frequency of the distributed PR circuit, it can result in dual-resonance excitation of the lowest resonant mode contributed by the shorted monopole strip to cover the LTE700/GSM850/900 operation. The antenna also occupies a small volume of 44 ¡Ñ 10 ¡Ñ 5 mm3 (about 2.2 cm3). Good radiation characteristics of the antenna are also obtained. For practical applications, effects of the electrical connection between the system ground plane and the surrounding metal elements such as the battery¡¦s metal casing and the handset metal midplate are studied. The simulated SAR (Specific Absorption Rate) and HAC (Hearing Aid Compatibility) results are also analyzed.

In this thesis, WWAN/LTE and LTE MIMO antennas for ultrabook computers are presented. The MIMO antenna system comprises an eight-band LTE/WWAN antenna and a three-band LTE antenna. The bandwidth of the eight-band LTE/WWAN antenna is enhanced by using an embedded parallel resonant circuit, which can result in dual-resonance excitation of the lowest resonant mode of the antenna. The bandwidth of the antenna¡¦s lower band can hence cover the LTE700/GSM850/900 operation. A design technique of improving the isolation of the MIMO antenna system is also presented. The isolation enhancement is obtained by embedding a 0.5-wavelength slot in the conductive supporting plate of the upper cover of the ultrabook computer. The embedded slot can attract the excited surface currents in the conductive supporting plate and decrease the coupling between the MIMO antennas through the coupling of the surface currents. The isolation between the MIMO antennas can hence be enhanced. Moreover, this technique will not lead to decreased radiation efficiency and impedance matching of the MIMO antennas, which is attractive for practical applications.