Conflicting Parameter Pair Optimization for Linear Aperiodic Antenna Array using Chebyshev Taper based Genetic Algorithm

In this study, the peak side lobe level (PSLL) in the radiation pattern of a linear antenna array (LAA) is lowered without affecting its first null beam width (FNBW). Antenna array synthesis is commonly applied to achieve high directivity, low side lobes, high gain and desired null positions in the output radiation pattern. But output parameters like PSLL, null positions and beam width conflict with each other, i.e. as one parameter improves, the other deteriorates. To avoid this problem, a multi-objective optimization algorithm can be implemented, in which both the conflicting parameters can be simultaneously optimized. This work proposes a multi-objective algorithm, which takes advantages of the well-known Chebyshev tapering and genetic algorithm (GA), to lower the PSLL without broadening the beam further. Array elements are fed using Chebyshev tapered excitations while GA is incorporated to optimize the elemental spacing. The results of 28-element LAA are compared with those of multi-objective Cauchy mutated cat swarm optimization (MO-CMCSO) existing in literature, which has also been proven to be superior to multi-objective cat swarm optimization (MO-CSO) and multi-objective particle swarm optimization (MO-PSO). Results indicate that the proposed algorithm performs better by further reducing the PSLL from -21.57 dB (MO-CMCSO) to -28.18 dB, while maintaining the same FNBW of 7.4 degrees

Bio-inspired optimization algorithms for smart antennas

This thesis studies the effectiveness of bio-inspired optimization algorithms in controlling adaptive antenna arrays. Smart antennas are able to automatically extract the desired signal from interferer signals and external noise. The angular pattern depends on the number of antenna elements, their geometrical arrangement, and their relative amplitude and phases. In the present work different antenna geometries are tested and compared when their array weights are optimized by different techniques. First, the Genetic Algorithm and Particle Swarm Optimization algorithms are used to find the best set of phases between antenna elements to obtain a desired antenna pattern. This pattern must meet several restraints, for example: Maximizing the power of the main lobe at a desired direction while keeping nulls towards interferers. A series of experiments show that the PSO achieves better and more consistent radiation patterns than the GA in terms of the total area of the antenna pattern. A second set of experiments use the Signal-to-Interference-plus-Noise-Ratio as the fitness function of optimization algorithms to find the array weights that configure a rectangular array. The results suggest an advantage in performance by reducing the number of iterations taken by the PSO, thus lowering the computational cost. During the development of this thesis, it was found that the initial states and particular parameters of the optimization algorithms affected their overall outcome. The third part of this work deals with the meta-optimization of these parameters to achieve the best results independently from particular initial parameters. Four algorithms were studied: Genetic Algorithm, Particle Swarm Optimization, Simulated Annealing and Hill Climb. It was found that the meta-optimization algorithms Local Unimodal Sampling and Pattern Search performed better to set the initial parameters and obtain the best performance of the bio-inspired methods studied

Geometry Modification Assessment and Design Optimization of Miniaturized Wideband Antennas

Maintaining small physical dimensions of antenna structures is an important consideration for contemporary wireless communication systems. Typically, antenna miniaturization is achieved through various topological modifications of the basic antenna geometries. The modifications can be applied to the ground plane, the feed line, and/or antenna radiator. Unfortunately, various topology alteration options are normally reported on a case-to-case basis. The literature is lacking systematic investigations or comparisons of different modification methods and their effects on antenna miniaturization rate as well as electrical performance. Another critical issue—apart from setting up the antenna topology—is a proper adjustment of geometry parameters of the structure so that the optimum design can be identified. Majority of researchers utilize experience-driven parameter sweeping which typically yields designs that are acceptable, but definitely not optimal. Furthermore, in many of the cases, the authors provide a cooperative progression before and after topological modifications that generally lead to a certain reduction of the antenna size, however, with appropriate parameter adjustment missing. Consequently, suitability of particular modifications in the miniaturization context is not conclusively assessed. In order to carry out such an assessment in a reliable manner, identification of the truly optimum design is necessary. This requires rigorous numerical optimization of all antenna parameters (especially in the case of complex antenna topologies) with the primary objective being size reduction, and supplementary constraints imposed on selected electrical or field characteristics. This thesis is an attempt to carry out systematic investigations concerning the relevance of geometry modifications in the context of wideband antenna miniaturization. The studies are carried out based on selected benchmark sets of wideband antennas. In order to ensure a fair comparison, all geometry parameters are rigorously tuned through EM-driven optimization to obtain the minimum footprint while maintaining acceptable electrical performance. The results demonstrate that it is possible to conclusively distinguish certain classes of topology alterations that are generally advantageous in the context of size reduction, as well as quantify the benefits of modifications applied to various parts of the antenna structure, e.g., with feed line modifications being more efficient than the ground plane and radiator ones. Several counterexamples have been discussed as well, indicating that certain modifications can be counterproductive when introduced ad hoc and without proper parameter tuning. The results of these investigations have been utilized to design several instances of novel compact wideband antennas with the focus on isolation improvement and overall antenna size reduction in multi-input-multi-output (MIMO) systems. Experimental validations confirming the numerical findings are also provided. To the best of the author’s knowledge, the presented study is the first systematic investigation of this kind in the literature and can be considered a step towards the development of better, low-cost, and more compact antennas for wireless communication systems.Fyrir þráðlaus fjarskiptakerfi er mikilvægt að tryggja að loftnet séu lítil að umfangi. Yfirleitt er smækkun loftneta náð með ýmis konar formbreytingum á grunngerðum þeirra. Formbreytingarnar geta verið á jarðtengingu, fæðilínu og / eða geislagjafa. Því miður er venjulega einungis sagt frá slíkum formbreytingum fyrir einstaka tilvik. Skortur er á kerfisbundnu mati og samanburði á mismunandi formbreytingum og hvaða áhrif þær hafa á smækkun og raffræðilega eiginleika loftneta. Annað mikilvægt atriði, fyrir utan að ákveða gerð formbreytingarinnar, er að velja stika sem lýsa nákvæmri lögun svo að bestuð hönnun geti átt sér stað. Flestir hönnuðir notast við þá aðferð að notast við stikaskimun sem byggir á reynslugögnum, en sú aðferð skilar almennt ásættanlegri hönnun, þó ekki bestaðri. Einnig er í mörgum tilvikum sagt frá samhliða þróun fyrir og eftir formbreytingu sem leiðir til smækkunar án þess að tilgreina breytingar á stikum. Fyrir vikið er erfitt að meta til hlítar ávinning af mismunandi formbreytingum. Til þess að framkvæma slíkt mat með áreiðanlegum hætti er nauðsynlegt að geta metið bestu hönnunarútfærslu nákvæmlega. Þetta kallar á ítarlega tölulega bestun allra stika sem lýsa loftnetinu (einkum fyrir loftnet flókinnar lögunnar) þar sem aðalmarkmkið bestunar er smækkun en skorður eru settar af raffræðilegum eiginleikum. Í þessari ritgerð er leitast við að kerfisbundna rannsókn á mikilvægi formbreytingna í tengslum við smækkun bandbreiðra loftneta. Rannsóknin byggir á völdum söfnum viðmiðunarloftneta. Til að tryggja rétt mat eru allir stikar er varða lögun stilltir með rafsegulfræðilegri hermun til að tryggja minnst rúmtak með ásættanlegum raffræðilegum eiginleikum. Niðurstöðurnar sýna að unnt er að greina, án vafa, ákveðna flokka formbreytinga sem eru að jafnaði til þess fallnir að smækka loftnet. Auk þessa er hægt að reikna ávinning af formbreytingum mismunandi hluta loftnetsins, t.d. að breytingar á fæðilínu eru almennt hagkvæmari en breytingar á geislagjafa eða jarðtengingu. Þá er greint frá nokkrum tilvikum þar sem tilfallandi formbreytingar geta verið til tjóns ef ekki stikaval er ekki gert með réttum hætti. Niðurstöður þessara rannsóknar hafa verið notaðar til að hanna nokkur nýstárleg breiðbandsloftnet með áherslu á smækkun og bættan aðskilnað fjölgátta (MIMO) loftneta. Töluleg hermun er sannreynd með tilraunum. Að bestu vitund höfundar er hér um fyrstu kerfisbundnu rannsókn þessarar gerðar að ræða og má reikna með að hún leiði til þróunar betri, ódýrari og smærri loftneta fyrir þráðlaus fjarskiptakerfi.The Ph.D. project was supported by the Icelandic Research Center (RANNIS) Grant 16329905

Space-Air-Ground Integrated 6G Wireless Communication Networks: A Review of Antenna Technologies and Application Scenarios

A review of technological solutions and advances in the framework of a Vertical Heterogeneous Network (VHetNet) integrating satellite, airborne and terrestrial networks is presented. The disruptive features and challenges offered by a fruitful cooperation among these segments within a ubiquitous and seamless wireless connectivity are described. The available technologies and the key research directions for achieving global wireless coverage by considering all these layers are thoroughly discussed. Emphasis is placed on the available antenna systems in satellite, airborne and ground layers by highlighting strengths and weakness and by providing some interesting trends in research. A summary of the most suitable applicative scenarios for future 6G wireless communications are finally illustrated

DISTRIBUTED PHASED ARRAY ANTENNAS IN WIDE AREA RFID

Ultra High Frequency (UHF) Radio Frequency Identification (RFID) has gained importance over the past two decades in many applications such as stock management, asset tracking and access control. For wide area applications, Distributed Antenna Systems (DAS) have been used to obtain good coverage with few antennas by making use of multiple spatially distributed antennas and phase dithering. This implements a far-field beamforming that maximises the instantaneous power at a tag. Separately, phased array antennas have also been used to increase the read range by increasing the effective field of view of an antenna and overcoming multipath fading through beam steering. This dissertation explores a combination of both approaches to improve RFID read ranges in wide interrogation zones. Distributed antenna arrays are explored in the context of delivering high tag detection probabilities in a multi-cell RFID system, while maximising inter-antenna separations. A Distributed Antenna Array System (DAAS) is designed and shown to be capable of providing comparable performance to a fixed DAS system with fewer antennas. The properties of the system are further studied and its upper performance limit is explored by modelling a hypothetical perfectly steerable antenna array. The concept of using perfectly steerable arrays is further explored to propose a cell-less RFID system, in which cell allocation in wide area RFID is replaced with a tag location-based interrogation requiring the global reader antenna population to be used for interrogation of all tags, leading to significant potential increases in inter-antenna separation, and consequently good coverage with fewer antennas. It is also argued that this system leads to the avoidance of complex reader anti-collision policies, since only a single central reader is now required. Finally, the design of a wide-scan-angle antenna array is presented as a compromise solution for perfectly steerable antennas, whist still keeping the desired property of being flat panel. A 3D RFID multi-antenna model is presented and used for simulating and analysing the various described systems and for system planning

Antenna Designs for 5G/IoT and Space Applications

This book is intended to shed some light on recent advances in antenna design for these new emerging applications and identify further research areas in this exciting field of communications technologies. Considering the specificity of the operational environment, e.g., huge distance, moving support (satellite), huge temperature drift, small dimension with respect to the distance, etc, antennas, are the fundamental device allowing to maintain a constant interoperability between ground station and satellite, or different satellites. High gain, stable (in temperature, and time) performances, long lifecycle are some of the requirements that necessitates special attention with respect to standard designs. The chapters of this book discuss various aspects of the above-mentioned list presenting the view of the authors. Some of the contributors are working strictly in the field (space), so they have a very targeted view on the subjects, while others with a more academic background, proposes futuristic solutions. We hope that interested reader, will find a fertile source of information, that combined with their interest/background will allow efficiently exploiting the combination of these two perspectives

Antenna Design for 5G and Beyond

With the rapid evolution of the wireless communications, fifth-generation (5G) communication has received much attention from both academia and industry, with many reported efforts and research outputs and significant improvements in different aspects, such as data rate speed and resolution, mobility, latency, etc. In some countries, the commercialization of 5G communication has already started as well as initial research of beyond technologies such as 6G.MIMO technology with multiple antennas is a promising technology to obtain the requirements of 5G/6G communications. It can significantly enhance the system capacity and resist multipath fading, and has become a hot spot in the field of wireless communications. This technology is a key component and probably the most established to truly reach the promised transfer data rates of future communication systems. In MIMO systems, multiple antennas are deployed at both the transmitter and receiver sides. The greater number of antennas can make the system more resistant to intentional jamming and interference. Massive MIMO with an especially high number of antennas can reduce energy consumption by targeting signals to individual users utilizing beamforming.Apart from sub-6 GHz frequency bands, 5G/6G devices are also expected to cover millimeter-wave (mmWave) and terahertz (THz) spectra. However, moving to higher bands will bring new challenges and will certainly require careful consideration of the antenna design for smart devices. Compact antennas arranged as conformal, planar, and linear arrays can be employed at different portions of base stations and user equipment to form phased arrays with high gain and directional radiation beams. The objective of this Special Issue is to cover all aspects of antenna designs used in existing or future wireless communication systems. The aim is to highlight recent advances, current trends, and possible future developments of 5G/6G antennas

Theory and Applications of Aperiodic (Random) Phased Arrays

A need for network centric topologies using mobile wireless communications makes it important to investigate new distributed beamforming techniques. Platforms such as micro air vehicles (MAVs), unattended ground sensors (UGSs), and unpiloted aerial vehicles (UAVs) can all benefit from advances in this area utilizing advantages in stealth, enhanced survivability and maximum maneuverability. Moreover, in this dissertation, electromagnetic radiation is investigated such that the signal power of each element is coherently added in the far-field region of a specified target direction with net destructive interference occurring in all other regions to suppress sidelobe behavior. This provides superior range and resolution characteristics for a variety of applications including; early warning radar, ballistic missile defense and search and rescue efforts. A wide variety of topologies can be used to confine geometrically these mobile random arrays for analysis. The distribution function for these topologies must be able to generalize the randomness within the geometry. By this means it is feasible to assume the random element distribution of a very large volumetric space will yield either a normal or Gaussian distribution. Therefore the underlying assumption stands that the statistically averaged beam pattern develops from an arrangement of uniformly or Gaussian distrusted elements; both confined to a variety of geometry of radius A and is further generalized using a simple theory based upon the Fourier Transform. Hence, this theory will be derived and serve as the foundation for advanced performance characteristics of these arrays such as its ability for sidelobe tapering, adaptive nulling and multi beam control. In addition it will be shown that for the most ideal of conditions a steerable beam pattern free of sidelobe behavior (better known as a Gaussian distribution) is quite possible. As well these random array structures will be shown to provide superior bandwidth capability over tradiational array structures since they are frequency independent. Last of all a summary of the random array analysis and its results concludes this dissertation

A new Measure for Optimization of Field Sensor Network with Application to LiDAR

This thesis proposes a solution to the problem of modeling and optimizing the field sensor network in terms of the coverage performance. The term field sensor is referred to a class of sensors which can detect the regions in 2D/3D spaces through non-contact measurements. The most widely used field sensors include cameras, LiDAR, ultrasonic sensor, and RADAR, etc. The key challenge in the applications of field sensor networks, such as area coverage, is to develop an effective performance measure, which has to involve both sensor and environment parameters. The nature of space distribution in the case of the field sensor incurs a great deal of difficulties for such development and, hence, poses it as a very interesting research problem. Therefore, to tackle this problem, several attempts have been made in the literature. However, they have failed to address a comprehensive and applicable approach to distinctive types of field sensors (in 3D), as only coverage of a particular sensor is usually addressed at the time. In addition, no coverage model has been proposed yet for some types of field sensors such as LiDAR sensors. In this dissertation, a coverage model is obtained for the field sensors based on the transformation of sensor and task parameters into the sensor geometric model. By providing a mathematical description of the sensor’s sensing region, a performance measure is introduced which characterizes the closeness between a single sensor and target configurations. In this regard, the first contribution is developing an Infinity norm based measure which describes the target distance to the closure of the sensing region expressed by an area-based approach. The second contribution can be geometrically interpreted as mapping the sensor’s sensing region to an n-ball using a homeomorphism map and developing a performance measure. The third contribution is introducing the measurement principle and establishing the coverage model for the class of solid-state (flash) LiDAR sensors. The fourth contribution is point density analysis and developing the coverage model for the class of mechanical (prism rotating mechanism) LiDAR sensors. Finally, the effectiveness of the proposed coverage model is illustrated by simulations, experiments, and comparisons is carried out throughout the dissertation. This coverage model is a powerful tool as it applies to the variety of field sensors

Antenna Design for 5G and Beyond

This book is a reprint of the Special Issue Antenna Design for 5G and Beyond that was published in Sensors