This work proposes wideband and broadband Planar Ultra-wideband Modular Antenna (PUMA) arrays designed to improve cost and reliability for high production volume commercial and military applications. The designs feature simplified PCB stack-ups with high dielectric constant (Dk) dimensionally stable materials to improve the manufacturing cost and yield. Additionally, the packages use ball grid array (BGA) interconnects, commonly used in digital electronics, for simple solder reflow integration with radio frequency (RF) electronics. While high Dk materials present practical manufacturing benefits, theoretical background will show how and why PUMA arrays lose frequency bandwidth and scan volume with high Dk materials. Further, a band limiting cavity mode will be shown to encroach into the frequency band of high Dk PUMA arrays due to a higher order common mode. PUMA arrays designed on several high Dk materials (Dk = {2.55, 3, 3.7}) will be presented to characterize this reduction in bandwidth. A wideband 7.25-31 GHz (4.3:1) PUMA array-on-package designed on Rogers RO4725JXR (Dk = 2.55) is presented with infinite array simulation results showing good active impedance match, port isolation and cross-polarization performance out to q = 45°. A simplified broadband 15-21 GHz (30%) PUMA array on a thin (λ/11) single layer of Isola FR408HR (Dk = 3.7) is proposed with infinite array results predicting strong active impedance, port isolation and cross-polarization performance with better port isolation and cross-polarization levels than a similar dual-polarized probe fed patch array.

The growing demand for high data rates, reliable connections, low latency, and increased user density has driven the operating frequency of modern wireless communication systems towards the millimeter-wave (mmWave) band. Large-scale antenna arrays capable of supporting simultaneous multi-beamforming are crucial for these mmWave systems. Passive beamforming networks, particularly Butler matrices (BM), offer several advantages for mmWave applications due to their low complexity, high energy efficiency, zero DC power consumption, and ability to generate multiple orthogonal beams. However, existing BM designs are often limited to low-order matrices, supporting a restricted number of radiating elements and featuring bulky cubic structures unsuitable for the microwave range. The contributions of this work include extensions in the Butler matrix order to support a massive antenna array, simplification of the Butler matrix topology to reduce the insertion loss, and layout optimization for straightforward antenna array integration. The novel multi-beam antenna systems for the one- and two-dimensional beamforming at mmWave band are designed and experimentally validated. First of all, a theoretical analysis of the Butler matrix topology is conducted to find effective solutions for matrix order extension, simplification, and loss reduction. Then, a multi-beam system consisting of a compact 8×8 one-dimension BM and an antenna array is implemented. To further extend the number of multi-beams, a 28 GHz multi-beam array system based on high-dimension 16 × 16 one-dimension BM and 1 × 16 linear antenna array is proposed. Additionally, a 28 GHz multi-beam array system fed by a planar 16 × 16 twodimensional Butler matrix is examined. Utilizing the proposed concept for the planarization of the cubic-formed two-dimensional Butler matrix, a system implemented with the multi-layer lamination in a dramatically reduced size provides 16 spatial orthogonal beams over a conical space. Furthermore, two new concepts for the planar and uni-planar 32 × 32 two-dimensional Butler matrix are developed not only for more beams but also to reduce the required signal layers.

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<p>In this thesis, design and realization of a system which enables precise positioning of RFID tags in both azimuth and elevation angles is explained. The positioning is based on measuring the phase difference between four Yagi antennas placed in two arrays. One array is placed in the azimuth plane and the other array is perpendicular to the first array in the elevation plane. The phase difference of the signals received from the antennas in the azimuth array is used to find the position of RFID tag in the horizontal direction. For the position in the vertical direction, the phase difference of the signals received from the antennas in the elevation plane is used. After that the position of tag in horizontal and vertical directions is used to control the mouse cursor in the horizontal and vertical directions on the computer screen. In this way by attaching one RFID tag to a plastic rod, a wireless pen is implemented which enables drawing in the air by using a program like Paint in Windows. Simulated results show that the resolution of the tag positioning in the system is in the order of 3mm in a distance equal to 0.5 meter in front of the array with few number of averaging over the received phase data. Using the system in practice reveals that it is easily possible to write and draw with this RFID pen. In addition it is argued how the system is totally immune to any counterfeit attempt for faked drawings by randomly changing the transmitting antenna in the array. This will make the system a novel option for human identity verification.</p> / QC 20100920

The proliferation of modern wireless networks increases demand for high capacity and throughput in order to provide faster, more robust, efficient and broadband services to end users. Mobile WiMAX and LTE are examples of such networks in which for some cases they have exposed limited connectivity due to harsh environment. Relay stations are preferred to overcome problems of weak or no access for such network devices, that are placed in specific positions to maintain high quality of data transfer at low cost and provide the required connectivity anywhere anytime. These stations should be equipped with an antenna system capable of establishing communication between base station (backhaul link) and end users (access link). This thesis focuses on the design and development of a new antenna system that is suitable for a relay-based wireless network. Planar geometries of microstrip patch antennas are utilized. The antenna system comprises two antenna modules: a new design of a single antenna for access link and a new design of an antenna array for backhaul link realization. Both antenna specifications are compatible with the IEEE802.16j protocol standard. Hence, relay station should be capable of pointing its radiation pattern to the base station antenna, thus to achieve the desired radiation pattern of the relay station, a new beam-forming module is proposed, designed and developed to generate the proper radiation pattern. The beam-forming module incorporating digital phase shifters and attenuator chips is fabricated and tested. The optimization process using the Least Mean Square (LMS) algorithm is considered in this study to assign the proper phase and amplitude that is necessary to each radiation element excitation current, to produce the desired steered radiation pattern. A comprehensive study on the coupling effects for several relative positions between two new backhaul and access link antenna elements is performed. Two new antenna configurations for coupling reduction are tested and the simulated and measured results in terms of antenna radiation performances were compared and commented.

Processing of broadband signals induced on an antenna array using a tapped delay line filter and a set of steering delays has two problems. Firstly one needs to manipulate large matrices to estimate the filter coefficients. Secondly the use of steering delays is not only cumbersome but implementation errors cause loss of system performance. This thesis looks at both of these problems and presents elegant solutions by developing and studying a design method referred to as the DFT method, which does not require steering delays and is computationally less demanding compared to existing methods. Specifically the thesis studies and compares the performance of a time domain element space beamformer using the proposed method and that using an existing method, and develops the DFT method when the processor is implemented in partitioned form. The study presented in the thesis shows that the processors using the DFT method are robust to look direction errors and require less computation than that using the existing method for comparable performance. The thesis further introduces a broadband beamformer design which does not require any steering delays between the sensors and the tapped delay line section as is presently the case. It has the capability of steering the array in an arbitrary direction with a specified frequency response in the look direction while canceling unwanted uncorrelated interferences. The thesis presents and compares the performance of a number of techniques to synthesize an antenna pattern of a broadband array. These techniques are designed to produce isolated point nulls as well as broad sector nulls and to eliminate the need for the steering delays. Two of the pattern synthesis techniques presented in the thesis allow optimization against unwanted interferences in unknown directions. The techniques allow formulation of a beamforming problem such that the processor is not only able to place nulls in specified directions but also able to cancel directional interferences in unknown directions along with a specified frequency response in the look direction over a band of interest. The thesis also presents a set of directional constraints such that one does not need steering delays and an array can be constrained in an arbitrary direction with a specified frequency response. The constraints presented in the thesis are simple to implement. Based on these constraints a pattern synthesis technique for broadband antenna array is also presented.

Dans le cadre de ce travail de recherche, nous nous somme intéressés à un système de télécommunication MIMO (Multiple Input Multiple Output) à multiplexage spatial utilisant des récepteurs Zero-IF et la technique de formation numérique de faisceaux (FF). Le domaine d'application de ces travaux de recherches peuvent être aussi bien les applications fixes (exp: WiFi, IEEE) que les applications mobiles (exp: LTE, 3GPP).<br /> La première partie de ce travail est consacrée à une étude comparative entre les différents types de démodulateurs cinq-port et triphasés. Cette étude a permis de mettre en évidence l'aspect tridimensionnel des démodulateurs cinq-port et triphasés, de gagner 20dB en termes de réjection des produits d'intermodulation des signaux adjacents et de trouver une nouvelle méthode de calibrage aveugle du récepteur.<br /> La seconde partie de la thèse se concentre sur le prototypage d'un système MIMO. Cette phase nous a permis d'exposer les difficultés de mise en place de ce genre de système et de souligner les nouvelles problématiques qui n'apparaissait pas auparavant dans les systèmes mono- transcepteur. Aussi, un algorithme de Formation de Faisceau a été développé dans cette partie. Ce FF numérique a permis non seulement d'accroître la capacité mais aussi la qualité de liaison en considérant le système MIMO comme N système SIMO en parallèle. Comparativement à la technique ZF(Zero Forcing), nous démontrons que le FF permet d'obtenir une meilleure qualité de signaux pour des faibles valeurs de rapport signal à bruit.

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

Tato diplomov prce se zabv anal­zou rznch napjec­ch struktur pro 2x2 fl­Äkov© antenn­ pole. Evaluace prob­h na stedn­ frekvenci 25.5GHz, kter spad do psma piazen©ho pt© generaci mobiln­ch komunikaÄn­ho standardu. Zvolen© napjec­ struktury byly napjen­ bl­zkm polem, napjen­ aperturou a napjen­ mikropskem.

The thesis describes the radiation of dipole antennas in near field area. More methods for evaluation of spatial dipole field arrangement are compared. The work target for practical use is to create software for simulation of near field values placed in planar or cylindrical observation plane. The computer programme is applicable to single dipole or dipole array. The limits for human body exposition of non-ionizing radiation are here implemented for compliance purpose in hygienic evaluations. The simulated results of field distribution are possible to display as graphs or save to data file. The results of own calculation are compared with results obtained by some commercial software as well by measurement of field components under model conditions.