Phased array antenna (PAA) is a key component in many of the modern military and commercial radar and communication systems requiring highly directional beams with narrow beam widths. One of the advantages that this technology offers is a physical movement-free beam steering. Radar and communication technologies also require the PAA systems to be compact, light weight, demonstrate high bandwidth and electromagnetic interference (EMI) free performance. Conventional electrical phase shifters are inherently narrowband. This calls for technologies that have a larger bandwidth and high immunity to electromagnetic interference. Optical true-time-delay (TTD) technique is an emerging technology that is capable of providing these features along with the ability to provide frequency independent beam steering. Photonic crystal fiber (PCF) based optical TTD lines are capable of providing precise and continuous time delays required for PAA systems. Photonic crystal fibers are a new class of optical fibers with a periodic arrangement of air-holes around a core that can be designed to provide extraordinary optical characteristics which are unrealizable using conventional optical fibers. In this dissertation, highly dispersive photonic crystal fiber structures based on index-guidance and bandgap-guidance were designed. Designs exhibiting dispersion coefficients as large as -9500ps/nm/km and 4000ps/nm/km at 1550nm were presented. A TTD module utilizing a fabricated highly dispersive PCF with a dispersion coefficient of -600ps/nm/km at 1550nm was formed and characterized. The module consisted of 4 delay lines employing highly dispersive PCFs connected with various lengths of non-zero dispersion shifted fibers. By employing PCFs with enhanced dispersion coefficients, the TTD module size can be proportionally reduced. A 4-element linear X-band PAA system using the PCF-TTD module was formed and characterized to provide continuous time delays to steer radiofrequency (RF) beams from -41 degrees to 46 degrees by tuning the wavelength from 1530nm to 1560nm. Using the PCF-TTD based X-Band PAA system, single and simultaneous multiple beam transmission and reception capabilities were demonstrated. Noise and distortion performance characteristics of the entire PAA system were also evaluated and device control parameters were optimized to provide maximum spurious-free-dynamic range. In order to alleviate computational and weight requirements of practical large PAA systems, a sparse array instead of a standard array needs to be used. X-Band sparse array systems using PCF and dispersive fiber TTD technique were formed and RF beam steering was demonstrated. As an important achievement during the research work, the design and fabricated structure of a PCF currently reported to have the highest dispersion coefficient of -5400ps/nm/km at 1549nm, along with its limitations was also presented. Finally, other interesting applications of highly dispersive PCFs in the areas of pulse compression and soliton propagation were explored. / text

This report describes a master thesis project work in machine design. The work has been done at the consulting firm Svea Teknik with DataPath as the customer. The subject of the project was to design a concept for a stabilized platform for a satellite antenna in an on-the-move application. The antenna that was to be implemented was a dual flat array antenna operating at the Ka frequency band. The platform should manage to operate both on roads and in terrain with shock loads up to 6g without exceeding 0.4° of pointing error and manage shock loads up to 30g without collapsing. The overall function was divided into three modules, elevation-separation of the panels, a sliding mechanism for one of the panels and a rotation mechanism for the whole panel system. Concepts were generated for the three modules separately. After evaluating the concepts one concept for each module was selected for further development where components were dimensioned by defining some load cases. All the components were then created and assembled in a CAD model. The result was an elevation-separation mechanism consisting of two EC motors with timing belts driving the elevation of the panels and an EC motor and a ball screw driving the separation of the panels. The sliding mechanism was guided by two linear guideways connected with a crossbar. The rotation was driven by an EC motor geared by a hypoid gear and a timing belt. When analyzing the pointing error when the system is subjected to the highest accelerations and shock loads at the same time the pointing error was 0.295 in the elevation plane and 0.158 in the azimuth plane, which gives a total angular error of 0.335° when combining elevation and azimuth errors. The pointing errors are lower than the required maximum pointing error. Though this error is only due to deflection and flexibility in the components and delay due to slow starting acceleration, no reaction rates and accuracies of the motors and control system were considered since no study of the control system was done in this project. The final pointing error could therefore not be calculated. The final concept does satisfy the most important requirements according to the defined load cases, though more studies need to be done to make sure the components are fast enough in combination with the control system. / Denna rapport beskriver ett masterexamensarbete inom maskinkonstruktion. Arbetet har utförts på konsultfirman Svea Teknik med DataPath som kund. Rapporten beskriver utvecklingen av ett koncept för en stabiliserande plattform till en satellitantenn för mobil applikation, i detta fall på en bil, för att kunna behålla satellitkontakten medan fordonet rör sig. Antennen som skulle appliceras var en tvådelad panelantenn som sänder inom Ka-frekvensbandet. Plattformen ska kunna användas både på vägar och i terräng med chocklaster upp till 6g, ha en maximal felpekning på 0,4°. Den ska även klara av chocklaster på upp till 30g utan att gå sönder. Den övergripande funktionen delades upp i tre moduler, elevation-separation av antennpanelerna, en glidmekanism för en av panelerna samt rotation av hela panelsystemet. Koncept genererades för de tre modulerna separat. Efter att ha utvärderat koncepten valdes ett koncept från varje modul för vidare utveckling där komponenter dimensionerades utefter några definierade lastfall. Alla komponenter togs sedan fram och sattes ihop till en CAD-modell. Resultatet blev en elevation-separationsmekanism bestående av två EC-motorer med kuggremsdrift som driver elevationen av panelerna och en EC-motor med kulskruv som driver separationen av panelerna. Glidmekanismen är lagrad med två linjärstyrningar sammankopplade med en tvärslå. Rotationsmekanismen drivs av en EC-motor med en hypoidväxel och en kuggremsdrift. Felpekningen då systemet utsätts för högsta möjliga acceleration och chocklaster på en och samma gång var 0,295° i elevationsled och 0,158° i azimutled. Detta ger en total felpekning på 0,335° vilket är lägre än den maximala tillåtna felpekningen. Men den beräknade felpekningen tar bara utböjning och flexibilitet i komponenterna samt eftersläpning på grund av för långsam acceleration i beaktning och inte reaktionshastigheten och noggrannheten i motorer och kontrollsystem. Detta på grund av att kontrollsystemet inte har behandlats i detta projekt. Den slutgiltiga felpekningen kunde därför inte beräknas. Slutkonceptet uppfyllde de viktigaste av kraven enligt de definierade lastfallen men fler och fördjupande studier behöver göras för att säkerställa att komponenterna är tillräckligt snabba i kombination med kontrollsystemet.

Radio frequency interference is an ever growing problem in the wireless community. This dissertation presents methods to reduce interference for vehicular multi-antenna devices. This document is organized into two parts: the main chapters and the appendices. The main chapters present research conducted primarily by the author. These deserve the reader's primary attention. The appendices showcase contributions made by the author serving in a supporting role to projects led by others and/or do not fit the vehicular theme. These should receive secondary attention. The main chapter contributions are summarized as follows. A device was created that provides over 105 dB of transmit to receive isolation in a full duplex printed circuit board radio. This technology can improve the effective range of vehicular radar systems and increase the bandwidth of full duplex communication schemes for vehicles. The technologies involved are compatible with existing circuit board topologies and are mindful of the size and weight requirements for vehicular use. This isolation performance pushes the state of the art for printed circuit board designs and provides greater capability for these kinds of devices. Recent system on chip computing architectures are opening new pathways for integrating phased array technologies into a single chip. The computer engineering required to configure these devices is beyond the capabilities of many vehicle systems engineers, inviting the author to use one to implement a 16 antenna adaptive beamformer for GPS. The adaptive beamformer can combat multipath bounces and malicious spoofing from ground sources. The high rate analog conversion architecture eliminates the local oscillator distribution to simplify the analog front end to an active antenna. This allows vehicular phased arrays to use smaller footprints and suggests that multi-antenna beamforming devices may be easier to deploy on small to midsized vehicles. Bench tests of the beamformer indicate it can adapt to the environment and increase the received signal strength suggesting it can improve GPS quality for active deployments. The bank of subspace projection beamformers is a popular choice for mitigating interference in digital phased array receivers. A method was discovered that maps that matrix operator into a circuit topology that is simple to implement in an analog circuit and cancels across the entire bandwidth simultaneously. This can offload computational interference mitigation from the signal processor while still allowing secondary multi-pixel digital beamforming downstream. This beamformer was analytically connected to the body of phased array literature and studied to estimate practical error bounds and design methods of calibration.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21108号 / 工博第4472号 / 新制||工||1695(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 篠原 真毅, 教授 山川 宏, 教授 木本 恒暢 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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京都大学 / 新制・課程博士 / 博士(工学) / 甲第23206号 / 工博第4850号 / 新制||工||1757(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 篠原 真毅, 教授 和田 修己, 教授 山本 衛 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Array antennas, and more specifically phased array antennas, are widely used in radar detection and communication systems because of their excellent beam scanning ability and simple control. Generally speaking, the scanning function can be realized in two ways: mechanically or electronically. Mechanical steering is done by rotating the whole structure, so there is a certain delay. The electronic scanning is done by controlling the relative relationship between the input signals of different array elements. Electronical scanning is then faster and easy to integrate with other circuits, which makes it an interesting solution to these applications. However, the disadvantage of electronic steering is that the scanning angle range is limited, which is generally within the range of ±60° . Beyond this range, the performance of the antenna will decrease considerably. One way to improve the antenna gain or expand the scanning range of the array antenna is to combine the array antenna with a dielectric radome. This thesis mainly studies how to adjust the shape of the dielectric radome with a center frequency of 28GHz to expand the beam scanning range of the two-dimensional array composed of rectangular waveguide ports. The inner and outer profiles of the dielectric lens follows the conics equation, and the shape of the lens can be controlled by adjusting different parameters. In this thesis, I adjust the lens shape according to three different objectives: 1. Increase the gain of the array antenna at the small scanning angle (0° ∼ 30°). The adjusted lens model increases the gain in this range by about 0.5 dBi; 2. Improve the gain of the array antenna at the large scanning angle (60° ∼ 80°). The final lens model increases the gain of the array antenna at the scanning angle of 70° and 80° by about 0.5 dBi and 1 dBi respectively; and 3. Improve the directivity of the array antenna in the range of 0° ∼ 70° . The final dielectric lens model improves the directivity in the broadside direction by about 1 dBi, and increases about 0.6 dBi when the scanning angle is 60° ; / Arrayantenner, och mer specifikt fasantenner, används ofta i radardetekterings- och kommunikationssystem på grund av deras utmärkta strålskanningsförmåga och enkla kontroll. Generellt kan skanningsfunktionen realiseras på två sätt: mekaniskt eller elektroniskt. Mekanisk styrning görs genom att rotera hela strukturen, så det finns en viss fördröjning. Den elektroniska skanningen görs genom att styra det relativa förhållandet mellan ingångssignalerna för olika arrayelement. Elektronisk skanning är då snabbare och lätt att integrera med andra kretsar, vilket gör det till en intressant lösning för dessa applikationer. Nackdelen med elektronisk styrning är dock att skanningsvinkeln är begränsad, vanligtvis mindre än ±60°. Utöver detta område kommer antennens prestanda att minska avsevärt. Ett sätt att förbättra antennförstärkningen eller utöka antennens skanningsområde är att kombinera arrayantennen med en dielektrisk radom. Denna avhandling studerar huvudsakligen hur man justerar formen på den dielektriska radomen med en centerfrekvens på 28GHz för att utöka strålskanningsområdet för den tvådimensionella array bestående av rektangulära vågledarportar. Den dielektriska linsens inre och yttre form följer konekvationen, och linsens form kan kontrolleras genom att justera olika parametrar. I denna avhandling justerar jag linsens form enligt tre olika mål: 1. Öka förstärkningen av antennen vid den lilla skanningsvinkeln (0° ∼ 30°). Den justerade linsmodellen ökar förstärkningen i detta område med cirka 0.5 dBi; 2. Förbättra förstärkningen av antennen vid den stora skanningsvinkeln (60° ∼ 80° ). Den slutliga modellen på linsen ökar förstärkningen av antennen i skanningsvinkeln 70° och 80° med cirka 0.5 dBi respektive 1 dBi; och 3. Förbättra riktigheten hos antennen i intervallet 0° ∼ 70°. Den slutliga dielektriska linsmodellen förbättrar riktningen i breddriktningen med ca 1 dBi, och ökar ca 0.6 dBi när skanningsvinkeln är 60°;

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper describes the Flexible Telemetry Transceiver (FNT)-a modular, scalable, standards-based, software configurable, microwave wireless telemetry network transceiver. The FNT enables flexible, high-rate, long-range, duplex, network services across multipoint to multipoint wireless channel.

Student Number : 9713144D - MSc Dissertation - School of Electrical Engineering - Faculty of Engineering and the Built Environment / The performance of the Log Periodic dipole array antenna has been characterized, in the form of parametric curves available in most antenna design handbooks and other relevant literature. These characteristic curves are often limiting in scope, as for instance they do not contain parametric curves giving the relationship between the boom-length 'L' and the number of dipole element 'N' for any given bandwidth, even when it is known that these two parameters are the main cost determinants of a LPDA Antenna. The concept of convergence is introduced to aid cost optimization of the LPDA Antenna in terms of number of dipole element 'N'. Although 'N' is used as the minimization criterion, the criteria for establishing convergence encompass all the main electrical characteristics of the LPDA Antenna, such as VSWR, gain and radiation patterns. Lastly, the effects of boomimpedance 'Zo' and length to diameter ration 'Ln/Dn', on the performance characteristics of the LPDA Antenna was investigated with the view to determining if neglecting the effects of these two parameters were responsible for the disparity in the directive gain values obtained by R. L Carrel compared to those obtained by later researchers. The investigation indicates that if an LPDA Antenna is converged, then the effects of Zo and Ln/Dn ratio though significant can not alone account for the fairly large disparity in the gain values. In other to perform these investigations, a modern scientific tool in the form of numerical modeling by method of moments based, Super Numerical electromagnetic code version2 was utilized. The numerical modeling tool was first validated by agreement between measured values and the values as predicted by the modeling tool. Next, simulation of the performance of LPDA antennas under variations of their number of elements was done. Thereafter, the means and standard deviations of the gain were extracted from the simulated numerical models. Trends in the pattern of variation of the means and standard deviations of the gain are used as the basis for deciding the value of number of element at which the antenna can yield acceptable performance (convergence criteria). These are presented as convergence curves, which gives for any given boom-length and operating bandwidth, the minimum number of elements required for the antenna to yield acceptable performance. Finally, the effect of length to diameter ratio and boom-impedance on the gain of optimized LPDA antennas are presented as parametric curves.

The delivery of tunable millimetre-wave components at 60GHz is of research and development interests with the advent of 5G era. Among applications such as high-data-rate wireless communications, high-precision automotive radars and hand-gesture sensing, variable phase shifters are vital components for antenna arrays to steer an electromagnetic beam without mechanical movement. However, present microwave technology has limited scope in meeting more and more stringent requirements in wavefront phase control and device performance for those cutting-edge applications in the millimetre-wavelength range. Although some existing microwave switchable techniques (such as RF MEMS and solid-state p-i-n diodes) can offer ultra-fast speed for phase modulation, their binary beam-steering nature is resolution-limited and thereby degrades the beam-scanning performance. In response to this, continuously-tunable phase shifting can be realised by using tunable dielectric materials such as ferroelectric BST and liquid crystals (LCs). BST thin films can offer relatively fast switching and modest tunability. However, the increased dielectric loss beyond 10GHz impedes their implementation for higher frequency applications. By comparison, liquid crystals (LCs) have drawn attention in recent years because of their continuous tunability as well as low losses especially at millimetre-wavebands. The principle of shifting the phase continuously is based on the shape anisotropy of LC molecules for variable polarizabilities and hence tunable dielectric constants, which allows wave speed to be controlled with ease by a low-frequency field of only up to 10V. However, LC-based tunable delay lines are not well established in the frequency regime of 60GHz-90GHz because of the limited status of LC microwave technology in which most of the LC based devices have been designed for below 40GHz. It is the aim of this PhD research to bridge the gap and address future societal needs based on our group's focus and experience in developing cutting-edge LC-based agile microwave components. In this work, a liquid crystal (LC) based 0-180˚continuously-variable phase shifter is developed with insertion loss less than -4.4dB and return loss below -15dB across a wide spectrum from 54GHz to 67GHz. The device is driven by a 0-10V AC bias and structured in a novel enclosed coplanar waveguide (ECPW) including an enclosed ground plate in the design, which significantly reduces the instability due to floating effects of the transmission line. This structure screens out interference and stray modes, allowing resonance-free quasi-TEM wave propagation up to 90GHz. The tunable ECPW is optimised by competing spatial volume distribution of the millimetre-wave signal occupying lossy tunable dielectrics versus low-loss but non-tunable dielectrics and minimising the total of dielectric volumetric loss and metal surface loss for a fixed phase-tuning range. A variety of influences affecting the actual device performance are studied, experimented and optimised. Fabricated prototypes exhibit wideband low-loss performance and 0-π continuous tuning with low power consumptions and high linearity compared with the state-of-the-arts. Potentially, the ECPW-fed phased antenna array will be incorporated with advanced beam-forming algorithms to develop compact beam-steering systems of improved performances and targeted for ultra-high-data-rate wireless communications, inter-satellite communications, current road safety improvement, futuristic autonomous driving, and other smart devices such as the hand-gesture recognition.