Yes / In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, exhibits left-handed metamaterial characteristics. The matching network is first theoretically modelled to gain insight of its limitations. It was then implemented directly in the 50-Ω feedline to a standard circular patch antenna, which is an unconventional methodology. The antenna’s performance was verified through measurements. With the proposed technique there is 2.7 dBi improvement in the antenna’s radiation gain and 12% increase in the efficiency at the center frequency, and this is achieved over a significantly wider frequency range by a factor of approximately twenty. Moreover, there is good correlation between the theoretical model, method of moments simulation, and the measurement results.

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.

Diploma thesis is focused to design of a system with circularly polarized wave for frequency band 2.4 GHz. The thesis introduces question of the microwave antennas, matching circuits and circular polarization circuit. It also includes a design of a circuit for available chip antenna (2450AT45A100) measurement and its measuring with connected chip antenna. Design and measurement of a circular polarization circuit using available chip antennas are also included in this thesis.

Yes / The paper demonstrates an effective technique to significantly enhance the bandwidth and radiation gain of an otherwise narrowband composite right/left-handed transmission-line (CRLH-TL) antenna using a non-Foster impedance matching circuit (NF-IMC) without affecting the antenna's stability. This is achieved by using the negative reactance of the NF-IMC to counteract the input capacitance of the antenna. Series capacitance of the CRLH-TL unit-cell is created by etching a dielectric spiral slot inside a rectangular microstrip patch that is grounded through a spiraled microstrip inductance. The overall size of the antenna, including the NF-IMC at its lowest operating frequency is 0.335λ0 × 0.137λ0 × 0.003λ0, where λ0 is the free-space wavelength at 1.4 GHz. The performance of the antenna was verified through actual measurements. The stable bandwidth of the antenna for |S11|≤ - 18 dB is greater than 1 GHz (1.4-2.45 GHz), which is significantly wider than the CRLH-TL antenna without the proposed impedance matching circuit. In addition, with the proposed technique the measured radiation gain and efficiency of the antenna are increased on average by 3.2 dBi and 31.5% over the operating frequency band. / This work is partially supported by RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE), and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1.

In this dissertation, a series of printed multiband antennas for slim mobile communication devices are presented. The study mainly focuses on how to effectively enhance the impedance bandwidth. With the equivalent LC matching circuit integrated in the antennas, wide impedance bandwidth can be obtained without increasing the size of the antennas. Note that the equivalent matching circuit can be formed by the coupling strip and the shorting strip to generate capacitance and inductance, respectively. In addition, the effects on the user's hand, head and whole body will be analyized. Also, the issue of the hearing aid compatibility will be discussed in this dissertation.

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.

<p>This thesis presents a study on built-in type low profile and low volume mobile phone antennas. In a coupling element based antenna, the chassis is the main radiator and the antenna elements are the exciters for the wave modes at low frequency. The main work of this thesis is to demonstrate and investigate the performance of the coupling element based antenna and study a variety of cases with different physical lengths and different physical heights. The investigation is done by using simulators. The performance is evaluated by analyzing the impedance bandwidth and the efficiency. For the study, antenna prototypes integrating miniaturized matching circuits were modeled. Two antenna structure prototypes covering five frequency bands were manufactured and measured. The Measured results are presented and compared with simulations. Finally, the performance of the coupling element based antenna is compared with planar inverter-F antenna (PIFA) and discussed.</p>

This thesis presents a study on built-in type low profile and low volume mobile phone antennas. In a coupling element based antenna, the chassis is the main radiator and the antenna elements are the exciters for the wave modes at low frequency. The main work of this thesis is to demonstrate and investigate the performance of the coupling element based antenna and study a variety of cases with different physical lengths and different physical heights. The investigation is done by using simulators. The performance is evaluated by analyzing the impedance bandwidth and the efficiency. For the study, antenna prototypes integrating miniaturized matching circuits were modeled. Two antenna structure prototypes covering five frequency bands were manufactured and measured. The Measured results are presented and compared with simulations. Finally, the performance of the coupling element based antenna is compared with planar inverter-F antenna (PIFA) and discussed.

This work deals with the most famous constructions of planar antennas. The work analyses selected methods of connecting planar antennas' charging with the possibility of impedance adaptation. An important part of the work consists of description of techniques for increasing bandwidth and conversely techniques for reducing the dimensions which are important for the design of planar antennas for mobile devices. The antennas were designed by means of theoretical basis and their properties were examined in the electromagnetic field simulator. The selected antenna model was constructed and its parameters were measured experimentally. The matching circuit for the antenna to tune it to different resonant frequencies was designed and constructed.