In this thesis, two novel broadband slot mobile phone antenna designs respectively for penta-band WWAN operation and eight-band LTE/WWAN operation are presented. The antennas are suitable to be mounted near the bottom edge of the system ground plane of the mobile phone. Good radiation characteristics for the antennas are obtained, and the two antennas respectively occupy a small printed area of 50 ¡Ñ 4 mm2 and 53 ¡Ñ 4 mm2. The first design uses a C-shaped strip connected to the bottom edge of the system ground plane to make the structure of the system ground plane close to a symmetric shorted dipole antenna. This makes it promising to excite a chassis mode to enhance the operating bandwidth of the antenna. The second one uses a microstrip feedline having a chip-inductor-loaded branch. The novel microstrip feedline can lead to more uniform distribution of the electric fields excited in the slot such that enhanced bandwidth of the antenna¡¦s lower band is obtained. Further, since the chip inductor performs like a low-pass filter, the original bandwidth of the antenna¡¦s upper band is not affected. Additionaly, the impedance matching of the lower frequencies of the upper band can be improved, which enhances the upper-band bandwidth of the antenna. Effects of the user¡¦s head and hand on the proposed antenna are also studied, and the simulated SAR and HAC issues are also analyzed in this thesis.

This thesis proposes a variety of antenna designs suitable for modern of mobile products, such as mobile phones, PDAs and so forth, on both the 2G and 3G communication systems according to the mobile communication development. Based on the integration of monopole or planar inverted-F antenna with the system ground planes, multi-frequency, broadband, and high radiation efficiency can be achieved, which is very promising to be adapted into communication products. Furthermore, an antenna capable of WLAN and UWB is proposed for future wireless communication applications.

This paper proposes novel PIFA and monopole designs for dual-band or multi-band wireless communications, especially for mobile phones and CF (compact flash) card. The dual-frequency designs for mobile phone mainly utilize one or more metal branch strips to excite two resonant modes. By tuning the dimensions of branch strips, the ratio of the antenna¡¦s first two resonant frequencies can be achieved to be about 2.0, which makes it very promising for 900/1800 MHz operations. In addition, the broadband and quad-band (AMPS/GSM/DCS/PCS) designs for mobile phone application are also proposed. The broadband antenna design, unlike the above-mentioned dual-frequency designs for operating at two separate resonant modes, is more suitable to cover several nearby communication bands (DCS/PCS/UMTS/WLAN 2.45 GHz). The quad-band antenna design utilizes a £k-shape matching bridge to achieve a wider bandwidth both in lower and higher bands. For CF Card application, the triangular chip antenna having one longer and one shorter strip lines can generate the lower and higher modes covering the WLAN 2.4 and WLAN 5.2/5.8 GHz bands. All the antenna designs proposed are very promising to be concealed within the housing of the mobile phones or CF card.

Novel printed monopole antennas, including diversity antennas, monopole array antennas and broadband antennas for WLAN operation, are experimentally studied and presented in this dissertation. These proposed antennas can be printed on dielectric substrates and practically integrated with system circuit boards by using printed circuit board technique. Also, the proposed antennas are low cost in fabrication and the reliability of system circuit boards can be improved. First, the design of the diversity antenna, which mainly comprises two substantially orthogonal printed monopoles and are placed symmetrically with respect to a protruded ground plane of T shape, shows good isolation between the two feeding ports of the proposed antenna. Second, the design of the printed array antenna, which comprises three equally-spaced equilateral-triangular monopoles, is proposed. Among the three monopoles, the center one has a larger size, which mainly controls the lower operation band, and the other two monopoles have a smaller size for higher operation band and show higher antenna gain and wider operating bandwidth. Finally, the quasi-self-complementary antenna is introduced. With compact size and wide bandwidth achieved, the proposed antenna is suitable for a mobile communication device, and can also provide good spatial diversity to combat the multi-path interference problem when mounting two proposed antennas appropriately spaced on a WLAN card.

The research of this thesis is on the mobile TV antenna designs. There are three antenna designs proposed in this thesis. The first two designs are for portable TV sets. They are different from the traditional straight monopole antenna because the two proposed designs can be built-in with the portable TV set. The third one is for laptop applications. It can be stored inside a laptop when the antenna is not in use, and can be pulled out of the laptop when in operation. Thus the proposed antenna will not affect the appearance of the laptop.

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.

Three novel wideband antennas suitable for DTV (Digital Television) signal reception in the 470 ~ 806 MHz band for Portable Media Playrer (PMP) applications are presented in this thesis. The antennas include a novel broadband planar monopole antenna in Chpater 2, a novel low-profile planar inverted-U monopole antenna in Chpater 3, and a novel internal planar inverted-F antenna in Chpater 4. These antennas all have wide impedance bandwidths, good radiation efficiencies, and good radiation patterns. In addition, we propose a one-layer simplified hand model for achieving efficient and reliable simulation study for PMP antennas. The studied antenna in Chapter 2 is selected to be the example to study the user¡¦s hand effect on the antenna for PMP application.

When the conventional mobile communication antennas embedded in the laptop computers, it is difficult to achieve enough bandwidths or a larger antenna size is required for covering the GSM/DCS operation. To overcome this problem, three new mobile communication internal antennas, having multi-band operation capability and suitable to be embedded in the laptop computers are proposed. At first, we introduce a monopole antenna with a shorted parasitic element. This antenna can provide wide bandwidths to cover GSM900, DCS, PCS, and UMTS operations. Then, in order to additionally achieve the GSM850 operation to form the penta-band operation, we present a wideband monopole antenna with a shorted structure. Finally, we propose an open-loop antenna with a shorted parasitic element. The antenna occupies a smaller volume and is capable of providing wide bandwidths to cover GSM850, GSM900, DCS, PCS, and UMTS operations. Detailed antenna designs and experimental results are presented and discussed.

A six-band antenna design for the mobile phone is presented. The required bandwidth for DTV/GSM850/900/DCS/PCS/UMTS operation is achieved by using two antennas. For DTV/GSM850/900 operation, we propose a novel antenna by using the concept of the dipole antenna and an internal matching portion to excite the half- and one-wavelength resonant modes of the antenna. With the internal matching portion, the frequency ratio of the two resonant modes can be controlled, thereby making the two resonant modes formed into a very wide operating band. For DCS/PCS/UMTS operation, a novel monopole slot antenna is used. The lower-edge frequency of the slot antenna depends on its length and the required bandwidth can be achieved by adjusting its tuning section. Effects of casing and human body on the proposed mobile phone antenna are also discussed. It is found that the radiation efficiency of DTV/GSM bands is larger than that of DCS/PCS/UMTS bands in this design. However, overall the operating bands, the antenna performances are greatly affected when the human effects are taken into considerations.

Kaluza-Klein theories generally in $(4+D)$ and more specifically in five dimensions are reviewed. The magnetic monopole solutions found in the Kaluza-Klein theories are generally reviewed and their generalizations to Anti-de Sitter spacetimes are discussed.