The Master´s thesis deals with the theoretical design, practical numerical analyses and optimalization of disc-like antenna and disc-like slot antenna. The antennas have relative omnidirectional radiation characteristics in the horizontal plane, respectively in the vertical plane. Antennas exploit the substrate integrated waveguide technology. The antennas themselves are designed for the purpose of making the antenna array that will be work as an antenna unit for access point. The antennas are manufactured and experimentally verified. The program CST Microwave Studio is used for simulation in the thesis.

This diploma thesis is focused on design of various antenna structures, based on slot antennas, created in the wider wall of a rectangular-shaped waveguide. As the substrate, it is used a 3D textile material, while its properties are examined. They were designed structures, that operate with linear and circular polarization, and other related structures, that are used for feeding and power division. Structures are designed to operate at central frequency of 8 GHz and its vicinity.

This master's thesis deals with the basic principles of slot antennas. Models of antennas were simulated in a selected electromagnetic simulator CST MICROWAVE STUDIO (CST MWS). There are several models of slot antennas which are optimized for communication in the car at a frequency 8 GHz.

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. / QC 20100920

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Power dividers are vital components and widely used in radio technology, such as antenna arrays, power amplifiers, multiplexers and mixers. A good example is the well-known Wilkinson power divider with its distinctive feeding network characteristics. A comprehensive review indicated that limited research is carried out in the area of planar multiport and reconfigurable power dividers in terms of the power levels between output ports. The main objectives of this work were to develop a small size power divider, a planer multi-output ports power divider and a power divider with a reconfigurable power division ratio. These power dividers were designed to operate over either an ultra-wideband frequency (3.1-10.6 GHz) or WLAN bands (2.4 or 5.2 GHz). A novel multi-layered topology solved the complexity of interconnecting isolation resistors by introducing an additional layer below the ground layer. The prototype was fabricated and tested to validate the results. The measurements and simulation were in good agreement. Finally, a novel uniplanar power divider with reconfigurable output power level difference was developed. The configurability feature was achieved by tuning the quarter wave transformer using one varactor diode. The power divider was applied to improve a full duplex system cancellation performance at the receiver element caused by interference from in-site transmitting antennas. This study investigated fixed power dividers, multi-output power dividers and reconfigurable power dividers. The measurements validated by the simulation results and applications proved the designed power dividers could be used in practical applications. / Higher Committee for Education Development (HCED), Iraq

This thesis is concentrated on the Angle / Direction of Arrival (A/DOA) estimation and Beamforming techniques that can be used in the current and future engineering applications such as tracking of targets, wireless mobile communications, radar systems, etc. This thesis firstly investigates different types of AOA and beamforming techniques. A comprehensive comparison between the common AOA algorithms is performed to evaluate the estimation accuracy and illustrate the computational complexity of each algorithm. The effect of mutual coupling between the radiators and the impact of the position-error of the antenna elements on the estimation accuracy is also studied. Then, several new efficient AOA methods for current wireless localisation systems are proposed. The estimation accuracy and computational complexity are compared with well-known AOA methods over a wide range of scenarios. New methodologies for Covariance Matrix (CM) sampling are proposed to enhance and improve operational performance without increasing the computational burden. A new beamforming algorithm is proposed and implemented on a compact mm-Wave linear and planar antenna arrays to enhance the desired signal and suppress the interference sources in wireless communication systems. The issue of asset tracking in dense environments where the performance of the Global Positioning System (GPS) becomes unavailable or unreliable is addressed in the thesis as well. The proposed solution uses a low-profile array of sensors mounted on a finite conducting ground. A compact-size omnidirectional spiral sensor array of six electrically small dual-band antenna elements was designed to operate in the 402 and 837 MHz spectrum bands. For the lower band, a three-element superposition method is applied to support the estimated AOA whereas six sensors are considered for the higher band. An efficient and low complexity Projection Vector (PV) AOA method is proposed. An Orthogonal Frequency Division Multiplexing (OFDM) modulation is integrated with the PV technique to enhance the estimation resolution. The system was found to be suitable for installation on top of vehicles to localise the position of assets. The proposed system was tested to track non-stationary objectives, and then two scenarios were investigated: outdoor to outdoor and outdoor to indoor environments using Wireless In-Site Software. The results confirm that the proposed tracking system works efficiently with a single snapshot. / Higher Commission for Education Development (HCED) in Iraq Basra Oil Company Ministry of Oil

Automotive radars have gained considerable interest in recent years for applications of road safety for vulnerable road users. The use of multipleinput and multiple-output (MIMO) technology in automotive radar has helped in realising a virtual aperture greater than the physical aperture of the antenna which has reduced the size of the overall radar module. But increasing the number of MIMO channels for greater angular resolution can introduce increased computational complexity, processing time and latency. A new type of radar using the multiple input multiple steered output (MIMSO) radar can alleviate these concerns by replacing the angle-FFT with beamforming by means of a lens. A double-layer lens with a beamforming layer and a radiating layer with a radiating aperture on the 2-D footprint of the lens is proposed as an antenna system for this new radar technique. This work focuses on the radiating aperture which has been realised as a travelling wave planar slotted array in gap waveguide technology due to its benefit of low losses and ease of manufacturing. A ridged gap waveguide is chosen for the reduction of the waveguide size and to avoid the appearance of grating lobes in the visible range for large scan angles. The planar slotted array is synthesised in the travelling wave configuration and reflection cancelling notches are used in the ridge to cancel the reflections from the slots. The aperture is chosen to be of a circular shape for a compact design and to maximise aperture efficiency. The planar array is verified with a full-wave simulation with a bandwidth of 76 to 81 GHz and a realised gain of 27.7 dBi at the centre frequency. The array can be scanned up to ±50◦ with a scan loss of 2.4 dBi. / Fordonsradarer har fått stort intresse under de senaste åren för tillämpningar av trafiksäkerhet för utsatta trafikanter. Användningen av MIMO-teknik (multipleinput och multiple-output) i bilradar har hjälpt till att realisera en virtuell bländaröppning som är större än antennens fysiska bländaröppning, vilket har minskat storleken på den totala radarmodulen. Men att öka antalet MIMOkanaler för större vinkelupplösning kan introducera ökad beräkningskomplexitet, bearbetningstid och latens. En ny typ av radar som använder MIMSO-radarn (multiple input multiple steered output) kan lindra dessa problem genom att ersätta vinkel-FFT med strålformning med hjälp av en lins. En dubbelskiktslins med ett strålformande skikt och ett strålande skikt med en strålande bländare på linsens 2D-fotavtryck föreslås som ett antennsystem för denna nya radarteknik. Detta arbete fokuserar på strålningsöppningen som har realiserats som en plan slitsad array i gap-vågledarteknologi på grund av dess fördel med låga förluster och enkel tillverkning. En vågledare med räfflade gap väljs för att minska vågledarstorleken och för att undvika uppkomsten av gitterlober i det synliga området för stora avsökningsvinklar. Den plana uppsättningen syntetiseras i den vandringsvågkonfigurationen och reflektionsupphävande skåror används i åsen för att eliminera reflektionerna från slitsarna. Bländaren är vald för att ha en cirkulär form för en kompakt design och för att maximera bländareffektiviteten. Planar arrayen verifieras med en helvågssimulering med en bandbredd på 76 till 81 GHz och en realiserad vinst på 27, 7 dBi vid mittfrekvensen. Arrayen kan skannas upp till ±50◦ med en skanningsförlust på 2, 4 dBi.

The dielectric antenna is an interesting alternative to a metallic antenna. This is mainlydue to its low manufacturing cost and the possibility to fabricate complex antennageometry with the aid of additive manufacturing (AM). Sophisticated AM technologyprovides new degrees of freedom in shaping the outer and inner geometry of antennas.This feature can be utilized to optimize various properties of antenna, such as itsbandwidth, radiation pattern etc, while maintaining a compact geometry.This master thesis investigates the possibility of improving the bandwidth of acompact dielectric antenna by modifying its geometry. Specifically, dielectricresonator antennas (DRAs) have been considered here. In this connection, twoembedded cylindrical DRAs operating within 8 GHz-17 GHz frequency band havebeen designed and simulated using Ansys HFSS. For the first design (Design-1), abandwidth (corresponding to reflection coefficient ≤ -10dB) of approximately 63%has been obtained and the second design (Design-2) has a bandwidth (correspondingto reflection coefficient ≤ -10dB) of about 57%. However, in terms of radiationcharacteristics, the performance of Design-2 has been found to be superior comparedto Design-1, mainly due to its symmetrical geometry. Furthermore, the two designshave been compared to an existing compact rectangular embedded DRA. It has beenfound that both Design-1 and Design-2 have comparatively wider bandwidth. Withrespect to the radiation characteristics, the performance of the reference antenna andDesign-2 are similar. While, the radiation performance of the reference antenna isfound to be better than Design-1. / Dielektriska antenner är ett intressant alternativ till metalliska diton. Detta beror delspå lägre tillverkningskostnader men också, tack vare additiva tillverkningsmetoder,på grund av möjligheten att använda komplexa geometrier. De senaste årens framsteginom additiv tillverkning har öppnat upp nya möjligheter vid designen av den externaoch den inre geometrin hos dielektriska antenner. Detta kan utnyttjas till att optimeraolika aspekter hos antennen, exempelvis bandbredd och strålningsmönster, utan attpåverka de yttre måtten.Denna avhandling studerar möjligheten att förbättra bandbredden hos dielektriskaresonansantenner (DRA) genom att modifiera deras inre. Två cylindriska DRA:er,verksamma inom 8-17 GHz, har designats och simulerats i Ansys HFSS. Bandbredderom 63 % för Design-1, samt 57 % för Design-2, erhölls. Trots den första designensstörre bandbredd uppvisar Design-2 bättre strålningsegenskaper, främst avseendeantennens strålningsmönster. De simulerade antennerna har också visat sig hastörre bandbredd jämfört med en redan existerande kompakt, inbäddad DRA. Sett tillstrålningsegenskaper är prestandan hos Design-2 jämförbar med referensantennen,medan design ett uppvisar sämre prestanda.

As the demand for wireless communication systems has exploded over the past few years, many researchers have taken on the challenge to model wireless channels more accurately. These models are very useful for enhancing the design of all aspects of wireless communications. Smart antennas and systems used in position location are among the most popular new studies that require signal information such as the amplitude, phase, and angle-of-arrival (AOA) of multipath delay spreads. For proper and efficient implementation of future systems, emerging wireless systems must be able to exploit processing of spatial information. The goal of the work presented in this thesis is to further improve two channel modeling tools, SMRCIM and SIRCIM, by implementing new geometrical models that provide users with angle-of-arrival information as well as amplitude and phase data for wideband wireless communication channels. The new angle-of-arrival models are explained and pseudo code is provided to demonstrate the software implementation of the models. Likewise, the channel models are explained and the usage and results of the simulation tools are described. The SMRCIM and SIRCIM tools are currently being used by researchers throughout the world. <i>[Vita removed March 5, 2012. Gmc]</i> / Master of Science