The past two decades have seen a surge in the number of applications requiring precise positioning data. Modern cellular networks offer many services based on the user's location, such as emergency services (e.g., E911), and emerging wireless sensor networks are being used in applications spanning environmental monitoring, precision agriculture, warehouse and manufacturing logistics, and traffic monitoring, just to name a few. In these sensor networks in particular, obtaining precise positioning data of the sensors gives vital context to the measurements being reported. While the Global Positioning System (GPS) has traditionally been used to obtain this positioning data, the deployment locations of these cellular and sensor networks in GPS-constrained environments (e.g., cities, indoors, etc.), along with the need for reliable positioning, requires a localization scheme that does not rely solely on GPS. This has lead to localization being performed entirely by the network infrastructure itself, or by the network infrastructure aided, in part, by GPS. In the literature, benchmarking localization performance in these networks has traditionally been done in a deterministic manner. That is, for a fixed setup of anchors (nodes with known location) and a target (a node with unknown location) a commonly used benchmark for localization error, such as the Cramer-Rao lower bound (CRLB), can be calculated for a given localization strategy, e.g., time-of-arrival (TOA), angle-of-arrival (AOA), etc. While this CRLB calculation provides excellent insight into expected localization performance, its traditional treatment as a deterministic value for a specific setup is limited. Rather than trying to gain insight into a specific setup, network designers are more often interested in aggregate localization error statistics within the network as a whole. Questions such as: "What percentage of the time is localization error less than x meters in the network?" are commonplace. In order to answer these types of questions, network designers often turn to simulations; however, these come with many drawbacks, such as lengthy execution times and the inability to provide fundamental insights due to their inherent ``block box'' nature. Thus, this dissertation presents the first analytical solution with which to answer these questions. By leveraging tools from stochastic geometry, anchor positions and potential target positions can be modeled by Poisson point processes (PPPs). This allows for the CRLB of position error to be characterized over all setups of anchor positions and potential target positions realizable within the network. This leads to a distribution of the CRLB, which can completely characterize localization error experienced by a target within the network, and can consequently be used to answer questions regarding network-wide localization performance. The particular CRLB distribution derived in this dissertation is for fourth-generation (4G) and fifth-generation (5G) sub-6GHz networks employing a TOA localization strategy. Recognizing the tremendous potential that stochastic geometry has in gaining new insight into localization, this dissertation continues by further exploring the union of these two fields. First, the concept of localizability, which is the probability that a mobile is able to obtain an unambiguous position estimate, is explored in a 5G, millimeter wave (mm-wave) framework. In this framework, unambiguous single-anchor localization is possible with either a line-of-sight (LOS) path between the anchor and mobile or, if blocked, then via at least two NLOS paths. Thus, for a single anchor-mobile pair in a 5G, mm-wave network, this dissertation derives the mobile's localizability over all environmental realizations this anchor-mobile pair is likely to experience in the network. This is done by: (1) utilizing the Boolean model from stochastic geometry, which statistically characterizes the random positions, sizes, and orientations of reflectors (e.g., buildings) in the environment, (2) considering the availability of first-order (i.e., single-bounce) reflections as well as the LOS path, and (3) considering the possibility that reflectors can either facilitate or block reflections. In addition to the derivation of the mobile's localizability, this analysis also reveals that unambiguous localization, via reflected NLOS signals exclusively, is a relatively small contributor to the mobile's overall localizability. Lastly, using this first-order reflection framework developed under the Boolean model, this dissertation then statistically characterizes the NLOS bias present on range measurements. This NLOS bias is a common phenomenon that arises when trying to measure the distance between two nodes via the time delay of a transmitted signal. If the LOS path is blocked, then the extra distance that the signal must travel to the receiver, in excess of the LOS path, is termed the NLOS bias. Due to the random nature of the propagation environment, the NLOS bias is a random variable, and as such, its distribution is sought. As before, assuming NLOS propagation is due to first-order reflections, and that reflectors can either facilitate or block reflections, the distribution of the path length (i.e., absolute time delay) of the first-arriving multipath component (MPC) is derived. This result is then used to obtain the first NLOS bias distribution in the localization literature that is based on the absolute delay of the first-arriving MPC for outdoor time-of-flight (TOF) range measurements. This distribution is shown to match exceptionally well with commonly assumed gamma and exponential NLOS bias models in the literature, which were only attained previously through heuristic or indirect methods. Finally, the flexibility of this analytical framework is utilized by further deriving the angle-of-arrival (AOA) distribution of the first-arriving MPC at the mobile. This distribution gives novel insight into how environmental obstacles affect the AOA and also represents the first AOA distribution, of any kind, derived under the Boolean model. In summary, this dissertation uses the analytical tools offered by stochastic geometry to gain new insights into localization metrics by performing analyses over the entire ensemble of infrastructure or environmental realizations that a target is likely to experience in a network. / Doctor of Philosophy / The past two decades have seen a surge in the number of applications requiring precise positioning data. Modern cellular networks offer many services based on the user's location, such as emergency services (e.g., E911), and emerging wireless sensor networks are being used in applications spanning environmental monitoring, precision agriculture, warehouse and manufacturing logistics, and traffic monitoring, just to name a few. In these sensor networks in particular, obtaining precise positioning data of the sensors gives vital context to the measurements being reported. While the Global Positioning System (GPS) has traditionally been used to obtain this positioning data, the deployment locations of these cellular and sensor networks in GPS-constrained environments (e.g., cities, indoors, etc.), along with the need for reliable positioning, requires a localization scheme that does not rely solely on GPS. This has lead to localization being performed entirely by the network infrastructure itself, or by the network infrastructure aided, in part, by GPS. When speaking in terms of localization, the network infrastructure consists of what are called anchors, which are simply nodes (points) with a known location. These can be base stations, WiFi access points, or designated sensor nodes, depending on the network. In trying to determine the position of a target (i.e., a user, or a mobile), various measurements can be made between this target and the anchor nodes in close proximity. These measurements are typically distance (range) measurements or angle (bearing) measurements. Localization algorithms then process these measurements to obtain an estimate of the target position. The performance of a given localization algorithm (i.e., estimator) is typically evaluated by examining the distance, in meters, between the position estimates it produces vs. the actual (true) target position. This is called the positioning error of the estimator. There are various benchmarks that bound the best (lowest) error that these algorithms can hope to achieve; however, these benchmarks depend on the particular setup of anchors and the target. The benchmark of localization error considered in this dissertation is the Cramer-Rao lower bound (CRLB). To determine how this benchmark of localization error behaves over the entire network, all of the various setups of anchors and the target that would arise in the network must be considered. Thus, this dissertation uses a field of statistics called stochastic geometry} to model all of these random placements of anchors and the target, which represent all the setups that can be experienced in the network. Under this model, the probability distribution of this localization error benchmark across the entirety of the network is then derived. This distribution allows network designers to examine localization performance in the network as a whole, rather than just for a specific setup, and allows one to obtain answers to questions such as: "What percentage of the time is localization error less than x meters in the network?" Next, this dissertation examines a concept called localizability, which is the probability that a target can obtain a unique position estimate. Oftentimes localization algorithms can produce position estimates that congregate around different potential target positions, and thus, it is important to know when algorithms will produce estimates that congregate around a unique (single) potential target position; hence the importance of localizability. In fifth generation (5G), millimeter wave (mm-wave) networks, only one anchor is needed to produce a unique target position estimate if the line-of-sight (LOS) path between the anchor and the target is unimpeded. If the LOS path is impeded, then a unique target position can still be obtained if two or more non-line-of-sight (NLOS) paths are available. Thus, over all possible environmental realizations likely to be experienced in the network by this single anchor-mobile pair, this dissertation derives the mobile's localizability, or in this case, the probability the LOS path or at least two NLOS paths are available. This is done by utilizing another analytical tool from stochastic geometry known as the Boolean model, which statistically characterizes the random positions, sizes, and orientations of reflectors (e.g., buildings) in the environment. Under this model, considering the availability of first-order (i.e., single-bounce) reflections as well as the LOS path, and considering the possibility that reflectors can either facilitate or block reflections, the mobile's localizability is derived. This result reveals the roles that the LOS path and the NLOS paths play in obtaining a unique position estimate of the target. Using this first-order reflection framework developed under the Boolean model, this dissertation then statistically characterizes the NLOS bias present on range measurements. This NLOS bias is a common phenomenon that arises when trying to measure the distance between two nodes via the time-of-flight (TOF) of a transmitted signal. If the LOS path is blocked, then the extra distance that the signal must travel to the receiver, in excess of the LOS path, is termed the NLOS bias. As before, assuming NLOS propagation is due to first-order reflections and that reflectors can either facilitate or block reflections, the distribution of the path length (i.e., absolute time delay) of the first-arriving multipath component (MPC) (or first-arriving ``reflection path'') is derived. This result is then used to obtain the first NLOS bias distribution in the localization literature that is based on the absolute delay of the first-arriving MPC for outdoor TOF range measurements. This distribution is shown to match exceptionally well with commonly assumed NLOS bias distributions in the literature, which were only attained previously through heuristic or indirect methods. Finally, the flexibility of this analytical framework is utilized by further deriving angle-of-arrival (AOA) distribution of the first-arriving MPC at the mobile. This distribution yields the probability that, for a specific angle, the first-arriving reflection path arrives at the mobile at this angle. This distribution gives novel insight into how environmental obstacles affect the AOA and also represents the first AOA distribution, of any kind, derived under the Boolean model. In summary, this dissertation uses the analytical tools offered by stochastic geometry to gain new insights into localization metrics by performing analyses over all of the possible infrastructure or environmental realizations that a target is likely to experience in a network.

Dans le cadre des nouvelles applications dans la bande de fréquence millimétrique, une évaluation de la technologie CMOS 65nm SOI pour la conception de circuits est proposée. Cette évaluation s'articule autour de deux axes principaux. Tout d'abord les composants actifs et passifs spécifiques à la technologie font l'objet d'une étude en terme de performances et de modélisations. Ensuite la technologie est évaluée au travers l'exemple de circuits composant une chaîne de réception

The objective of the proposed research is to develop solutions for High-Performance Low-Cost Passives for Radar, Identification, and Communication Applications up to mm-Wave Frequencies. This research will bring to the table potential solutions that will meet three main requirements: small size (or low weight), high performance, and low cost. This research embarks on antenna design and development for passive RFID tags on LCP substrates, and then a transition towards lower cost modules investigates and explores the possibilities of using paper as RF substrates with inkjet printing as a low cost fabrication technology. Modules such as dual band antenna for Wifi frequencies (2.4 GHz and 5 GHz) and UWB (up to 10GHz) on paper substrate using inkjet printing are presented. This work then bridges into developing higher frequency modules. These include: highly selective filter design on LCP for X-band Radar application to be used as a benchmark for an easy adjustment for higher frequencies, and antenna modules LCP using inkjet printing for communication such as mm-Wave WLAN or WPAN. A transition into mm-Wave Modules then takes place for the general realization of low-cost high-performance mm-Wave modules and more specifically the low cost automotive radar. After proposing an architecture for integrated mm-Wave module, this work then investigates 2D/3D interconnections (and their integration with antennas) on LCP using conventional etching design guidelines up to 100GHz. Antenna arrays that are implemented with phase shifters for beam steering are then designed using edge fed and multilayer technology. Furthermore, crosstalk reductions for highly dense transmission lines are analyzed via simulations for the optimum performance and space saving of such mm-Wave modules such as the IC interface where space restrictions are strictly enforced.

Inkjet-printing is a technology which has for the last decade been exploited to fabricate flexible RF components such as antennas and planar circuit elements. However, the limitations of feature size and single layer fabrication prevented the demonstration of compact, and high efficiency RF components operating above 10 GHz into the mm-Wave regime which is critical to silicon integration and fully-printed modules. To overcome these limitations, a novel vertically-integrated fully inkjet-printed process has been developed and characterized up to the mm-Wave regime which incorporates up to five highly conductive metal layers, variable thickness dielectric layers ranging from 200 nm to 200 um, and low resistance through-layer via interconnects. This vertically-integrated inkjet printed electronics process, tagged VIPRE, is a first of its kind, and is utilized to demonstrate fully additive RF capacitors, inductors, antennas, and RF sensors operating up to 40 GHz. In this work, the first-ever fully inkjet printed multi-layer RF devices operating up to 40 GHz with high-performance are demonstrated, along with a demonstration of the processing techniques which have enabled the printing of multi-layer RF structures with multiple metal layers, and dielectric layers which are orders of magnitude thicker than previoulsy demonstrated inkjet-printed structures. The results of this work show the new possibilities in utilizing inkjet printing for the post-processing of high-efficiency RF inductors, capacitors, and antennas and antenna arrays on top of silicon to reduce chip area requirements, and for the production of entirely printed wireless modules.

Recent advancements in silicon technology have paved the way for the development of integrated transceivers operating well inside the mm-wave frequency range (30 - 300 GHz). This band offers opportunities for new applications such as remote sensing, short range radar, active imaging and multi-Gb/s radios. This thesis presents new ideas at the circuit and system level for a variety of such applications, up to 145 GHz and in both state-of-the-art nanoscale CMOS and SiGe BiCMOS technologies. After reviewing the theory of operation behind linear and power amplifiers, a purely digital, scalable solution for power amplification that takes advantage of the significant ft/fmax improvement in pFETs as a result of strain engineering in nanoscale CMOS is presented. The proposed Class-D power amplifier, features a stacked, cascode CMOS inverter output stage, which facilitates high voltage operation while employing only thin-oxide devices in a 45 nm SOI CMOS process. Next, a single-chip, 70-80 GHz wireless transceiver for last-mile point-to-point links is described. The transceiver was fabricated in a 130 nm SiGe BiCMOS technology and can operate at data rates in excess of 18 Gbps. The high bitrate is accomplished by taking advantage of the ample bandwidth available at the W-band frequency range, as well as by employing a direct QPSK modulator, which eliminates the need for separate upconversion and power amplification. Lastly, the system and circuit level implementation of a mm-wave precision distance and velocity sensor at 122 and 145 GHz is presented. Both systems feature a heterodyne architecture to mitigate the receiver 1/f noise, as well as self-test and calibration capabilities along with simple packaging techniques to reduce the overall system cost.

Recent advancements in silicon technology have paved the way for the development of integrated transceivers operating well inside the mm-wave frequency range (30 - 300 GHz). This band offers opportunities for new applications such as remote sensing, short range radar, active imaging and multi-Gb/s radios. This thesis presents new ideas at the circuit and system level for a variety of such applications, up to 145 GHz and in both state-of-the-art nanoscale CMOS and SiGe BiCMOS technologies. After reviewing the theory of operation behind linear and power amplifiers, a purely digital, scalable solution for power amplification that takes advantage of the significant ft/fmax improvement in pFETs as a result of strain engineering in nanoscale CMOS is presented. The proposed Class-D power amplifier, features a stacked, cascode CMOS inverter output stage, which facilitates high voltage operation while employing only thin-oxide devices in a 45 nm SOI CMOS process. Next, a single-chip, 70-80 GHz wireless transceiver for last-mile point-to-point links is described. The transceiver was fabricated in a 130 nm SiGe BiCMOS technology and can operate at data rates in excess of 18 Gbps. The high bitrate is accomplished by taking advantage of the ample bandwidth available at the W-band frequency range, as well as by employing a direct QPSK modulator, which eliminates the need for separate upconversion and power amplification. Lastly, the system and circuit level implementation of a mm-wave precision distance and velocity sensor at 122 and 145 GHz is presented. Both systems feature a heterodyne architecture to mitigate the receiver 1/f noise, as well as self-test and calibration capabilities along with simple packaging techniques to reduce the overall system cost.

Although the majority of wireless receiver subsystems have moved to digital signal processing over the last decade, the low noise amplifier (LNA) remains a crucial analogue subsystem in any design being the dominant subsystem in determining the noise figure (NF) and dynamic range of the receiver as a whole. In this research a novel LNA configuration, namely the LC-ladder and capacitive shunt-shunt feedback topology, was proposed for use in the implementation of very wideband LNAs. This was done after a thorough theoretical investigation of LNA configurations available in the body of knowledge from which it became apparent that for the most part narrowband LNA configurations are applied to wideband applications with suboptimal results, and also that the wideband configurations that exist have certain shortcomings. A mathematical model was derived to describe the new configuration and consists of equations for the input impedance, input return loss, gain and NF, as well as an approximation of the worst case IIP3. Compact design equations were also derived from this model and a design strategy was given which allows for electronic design automation of a LNA using this configuration. A process for simultaneously optimizing the circuit for minimum NF and maximum gain was deduced from this model and different means of improving the linearity of the LNA were given. This proposed design process was used successfully throughout this research. The accuracy of the mathematical model has been verified using simulations. Two versions of the LNA were also fabricated and the measured results compared well with these simulations. The good correlation found between the calculated, simulated and measured results prove the accuracy of the model, and some comments on how the accuracy of the model could be improved even further are provided as well. The simulated results of a LNA designed for the 1 GHz to 18 GHz band in the IBM 8HP process show a gain of 21.4 dB and a minimum NF of only 1.7 dB, increasing to 3.3 dB at the upper corner frequency while maintaining an input return loss below -10 dB. After steps were taken to improve the linearity, the IIP3 of the LNA is -14.5 dBm with only a small degradation in NF now 2.15 dB at the minimum. The power consumption of the respective LNAs are 12.75 mW and 23.25 mW and each LNA occupies a chip area of only 0.43 mm2. Measured results of the LNA fabricated in the IBM 7WL process had a gain of 10 dB compared to an expected simulated gain of 20 dB, however significant path loss was introduced by the IC package and PCB parasitics. The S11 tracked the simulated response very well and remained below -10 dB over the feasible frequency range. Reliable noise figure measurements could not be obtained. The measured P1dB compression point is -22 dBm. A 60 GHz LNA was also designed using this topology in a SiGe process with ƒT of 200 GHz. A simulated NF of 5.2 dB was achieved for a gain of 14.2 dB and an input return loss below -15 dB using three amplifier stages. The IIP3 of the LNA is -8.4 dBm and the power consumption 25.5 mW. Although these are acceptable results in the mm-wave range it was however found that the wideband nature of this configuration is redundant in the unlicensed 60 GHz band and results are often inconsistent with the design theory due to second order effects. The wideband results however prove that the LC-ladder and capacitive shunt-shunt feedback topology is a viable means for especially implementing LNAs that require a very wide operating frequency range and also very low NF over that range. / Thesis (PhD(Eng))--University of Pretoria, 2011. / Electrical, Electronic and Computer Engineering / unrestricted

There are more connected wireless devices than everbefore and with the rise of new smart systems such as self-drivingcars and smart cities new antenna solutions for transmittingsignals are needed. One important part of these systems is thefilters which filter out all the unwanted signals. In this report,we present a solution for manufacturing such a filter with apassband from 26-29 GHz and a stopband from 29-60 GHz usinga fully metallic glide-symmetric structure. Ideas of combiningmultiple unit cell designs to achieve wider stopbands and higherattenuation are explored using dispersion engineering wherethe advantages and the disadvantages of using this method arepresented. Furthermore, ways of combining the filter to standardconnections using a coaxial cable to waveguide transition areproposed and designed. The usage of multiple unit cell designsis proven to be a solution for achieving wider stopbands withminimum coupling between modes. / Det finns fler trådlösa enheter uppkoppladeän n°agonsin tidigare och med ökningen av nya smarta systemsom självkörande bilar och smarta städer finns ett behov av nyaantennlösningar för överföring av information. En viktig del avdessa system är filtren som filtrerar bort alla oönskade signaler.I denna rapport presenterar vi en lösning för att konstrueraett sådant filter med ett passband från 26-29 GHz och ettstoppband från 29-60 GHz med en helt metallisk glidsymmetriskstruktur. Id´eer att kombinera flera enhetscellsdesigner för attuppnå bredare stoppband och högre attenuering undersöks medhjälp av dispersionsteknik, där fördelarna och nackdelarna medatt använda denna metod presenteras. Dessutom föreslås ochutformas sätt att kombinera filtret till standardanslutningar meden koaxialkabel till vågledarövergång. Användningen av fleraenhetscell designer visar sig vara en lösning för att skapa bredastoppband med minimal koppling mellan ”modes”. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

L’objectif de ce travail de thèse est le développement en technologie intégrée standard d’une structure de ligne de transmission optimisée en termes de pertes, d’encombrement, de facteur de qualité et surtout du choix du niveau de couplage aux fréquences millimétriques. Cette structure a été nommée CS-CPW (Coupled Slow-wave CoPlanar Waveguide). Dans un premier temps, la théorie ainsi que les modèles électriques des CS-CPW sont présentés. Grâce aux modèles et aux simulations électromagnétiques, des coupleurs directionnels avec plusieurs valeurs de couplage (3 dB, 10 dB, 18 dB) ont été conçus en technologie BiCMOS 55 nm. Ils présentent tous une très bonne directivité, elle est toujours supérieure à 15 dB. Un premier prototype de coupleur a été mesuré à 150 GHz. Dans un deuxième temps, des filtres à la base des lignes couplées ont été développés à 80 GHz en utilisant des lignes CS-CPW. Les résultats des simulations présentent des résultats concurrentiels avec l’état de l’art : 11% de bande passante relative et un facteur non-chargé autour de 25. Finalement, trois projets ont démarré à la base de ces lignes. Ces projets sont actuellement utilisés dans deux travaux de thèse et un stage : un RTPS à 47 GHz, un isolateur à 75 GHz et un balun à 80 GHz. / This work focuses on high-performances CS-CPW (Coupled Slow-wave CoPlanar Waveguide) transmission lines in classical CMOS integrated technologies for the millimiter-wave frequency band. First, the theory as well as the electrical models of the CS-CPW are presented. Thanks to the models and electromagnetic simulations, directional couplers with different coupling levels (3 dB, 10 dB, 18 dB) were designed in BiCMOS 55 nm technology. They have a good directivity, always better than 15 dB. A first prototype of a coupler was measured at 150 GHz presenting good agreement with the simulations. Next, coupled-line base filters were developed at 80 GHz using the CS-CPWs. Simulation present competitive results with the state-of-art: 11% of fractional bandwidth and a unload quality factor of 25. Finally, three projects started based on the CS-CPWs. The projects are currently used in two theses and one internship: a RTPS at 47 GHz, an isolator at 75 GHz and a balun at 80 GHz.

La demande toujours croissante de connectivité et de débit de données requiert une rupture dans la conception des futurs réseaux de communication et systèmes radio. Plusieurs applications émergentes en bande millimétrique, notamment les réseaux mobiles de cinquième génération (5G) et les communications satellites, exigent des antennes large bande qui assurent une grande couverture angulaire, tout en étant à la fois compactes, facilement intégrables et à bas coût.Cette thèse propose des systèmes antennaires multifaisceaux large bande et à très grande couverture angulaire, appelés «Continuous Transverse Stub Antenna» (CTS), pour réaliser un bon compromis de l’ensemble de ces objectifs. L’architecture de l’antenne comprend un réseau de fentes longues excitées par un réseau d’alimentation en chandelier, basé sur des guides d’onde à plans parallèles. Cette structure est excitée par un formateur de faisceaux quasi-optique co-intégré. La première partie du manuscrit présent des nouveaux modèles numériques qui facilitent la conception de chaque sous-système de l’antenne et permettent l’analyse des performances globales, soit en termes d’adaptation, soit en termes de diagrammes de rayonnement. Ces outils sont exploités pour la conception d’antenne et pour étudier les limites en balayage. La thèse se poursuit en présentant de nouvelles solutions technologiques et de nouveaux design pour intégrer les antennes CTS dans des modules multicouches planaires et à faible profil. La conception et la caractérisation de deux antennes intégrées en technologie LTCC pour des points d’accès 5G à 60 GHz sont discutées. L’une des deux est à faisceau fixe, l’autre est à balayage électronique, avec une couverture de ±40°, de faibles lobes secondaires et un niveau élevé de recoupement des faisceaux. Enfin, nous proposons l’association de radomes polarisants planaires à faible profil aux antennes CTS, pour réaliser des systèmes rayonnants en polarisation circulaire. Une méthodologie systématique pour la conception de polarisateurs à très large bande est présentée, ainsi qu’un design couvrant entièrement la bande Ka pour des applications satellites. / The ever-growing demand for fast and seamless connectivity shows the need of new wireless standards and technologies. Novel broadband, wide-angle scanning antennas achieving an optimal trade-off among size, gain, efficiency and costs are crucial to the development of emerging applications at millimeter waves, such as fifth-generation (5G) mobile networks and satellite communications. In this thesis, multibeam parallel-fed continuous transverse stub (CTS) array antennas are proposed as possible candidates for future mm-wave communications and are developed to tackle these requirements. The antenna architecture comprises an array of long slots, a corporate feed network based on parallel plate waveguides (PPWs) and an integrated quasi-optical beamformer. First, novel numerical models for the analysis of each subsystem and of the overall antenna, are presented, which enable an efficient and modular design of CTS antennas. These tools are exploited to derive design guidelines and assess the scanning performance. Then, novel design and technological solutions for the integration of CTS antennas in flat, low-profile multilayer modules are discussed. The design and characterization of two prototypes in LTCC technology, for 60-GHz mobile access points are presented: a fixed beam array and a switched-beam antenna with a field of view of ±40°, low SLLs and high beam overlap. Finally, planar linear-to-circular polarization converters are proposed to realize circularly polarized CTS antenna systems. A procedure to achieve an ultra-wideband, low-loss polarization conversion is outlined and a design for Ka-band satellite application is presented.