<p>The study is concerned with how the hane effects on matching on mobile terminal antennas.</p>

The study is concerned with how the hane effects on matching on mobile terminal antennas.

In this thesis, an LTE/WWAN planar loop antenna for tablet computer with a compact size of 75 ¡Ñ 12 mm2 is presented. The planar loop antenna comprises a printed loop strip and a patch monopole encircled therein. By embedding a printed distributed inductor in the loop strip, whose effect is similar to a chip inductor, a parallel resonant mode is generated owing to the contributed inductance of the distributed inductor and the contributed capacitance of the coupling between the loop strip and the patch monopole. The parallel resonant mode leads to increase input resistance of the 0.5-wavelength loop mode at the high-frequency tail and a zero reactance nearby the original resonance of the 0.5-wavelength loop mode, thereby resulting in a dual-resonance excitation to greatly enhance the bandwidth of the antenna¡¦s lower band for the LTE700/GSM850/900 operation. In addition, the patch monopole, which performs not only as a coupling feed but also an efficient radiator, provides a 0.25-wavelength resonant mode to combine with a higher-order resonant mode contributed by the printed loop strip to form the antenna¡¦s upper band to cover the GSM1800/1900/UMTS/LTE2300/2500 operation. Further, the required distance between the antenna and the testing flat phantom to meet the 1-g body SAR requirement of 1.6 W/kg is discussed. A comparison of the body SAR value of the planar loop antenna and the bent loop antenna is also discussed.

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.

Novel chip antennas having an attractive EMC¡]Electromagnetic Compatibility¡^property for WLAN¡]Wireless Local Area Network¡^operations are demonstrated in this thesis. With the EMC property, the proposed antennas are suitable to be applied as internal antennas in mobile communication devices, such as the smart phones or PDA¡]Personal Digital Assistant¡^phones. With the antenna ground portion functioning as a new ground structure, the EM fringing fields in the surrounding region of the proposed antennas are greatly reduced to be negligible. When the possible RF shielding metal case or other electronic components are placed close to the proposed antennas, the antenna performances are almost unaffected. In other words, the isolation distance between the antenna and the nearby components will be no long required. This can lead to a compact integration of the proposed antennas with the nearby components in mobile communication devices. Details of the measured and simulated results of the proposed EMC chip antennas are presented and discussed.

This thesis describes a brief history of radio and electromagnetic waves from a physical point of view. It focuses mainly on radio waves in the VHF and subsequent construction of a radio network in this band. It uses the knowledge of the writer of this wavelength. This thesis is intended as a guide for fellow author.

Today, owners of small communicating device are interested in transmitting or receiving various multimedia data. By increasing the number of antennas at the transmitter and/or the receiver side of the wireless link, the diversity/Multiple-Input Multiple-Output (MIMO) techniques can increase wireless channel capacity without the need for additional power or spectrum in rich scattering environments. However, due to the limited space of small mobile devices, the correlation coefficients between MIMO antenna elements are very high and the total efficiencies of MIMO elements degrade severely. Furthermore, the human body causes high losses on electromagnetic wave. During the applications, the presence of users may result in the significant reduction of the antenna total efficiencies and highly affects the correlations of MIMO antenna systems. The aims of this thesis are to investigate and enhance the MIMO/diversity performance of multiple antenna systems in the free space and the presence of users. The background and theory of multiple antenna systems are introduced briefly first. Several figures of merits are provided and discussed to evaluate the multiple antenna systems. The decoupling techniques are investigated in the multiple antenna systems operating at the higher frequencies (above 1.7 GHz) and with high radiation efficiency. The single, dual and wide band isolation enhancements are realized through the half-wavelength decoupling slot, quarter-wavelength decoupling slot with T-shaped impedance transformer, tree-like parasitic element with multiple resonances, as well as the different polarizations and radiation patterns of multiple antennas. In the lower bands (lower than 960 MHz), due to the low radiation efficiency and strong chassis mode, the work mainly focused on how to directly reduce the correlations and enlarge the total efficiency. A new mode of mutual scattering mode is introduced. By increasing the Q factors, the radiation patterns of multiple antennas are separated automatically to reduce the correlations. With the inter-element distance larger than a certain distance, a higher Q factor also improved the total efficiency apart from the low correlation. A wideband LTE MIMO antenna with multiple resonances is proposed in mobile terminals. The high Q factors required for the low correlation and high efficiencies in mutual scattering mode is reduced with another mode of diagonal antenna-chassis mode. Hence, the bandwidth of wideband LTE MIMO antenna with multiple resonances mentioned above can be further enlarged while maintaining the good MIMO/diversity performance. The user effects are studied in different MIMO antenna types, chassis lengths, frequencies, port phases and operating modes. Utilizing these usefully information, an adaptive quad-element MAS has been proposed to reduce the user effects and the some geranial rules not limited to the designed MAS have also been given. / <p>QC 20130121</p> / EU Erasmus Mundus External Cooperation Window TANDEM