Co-design of Reconfigurable and Multifunction Passive RF/Microwave Components

In order to meet the market demands, multi-band communication systems that are able to accommodate different wireless technologies to be compatible with different wireless standards should be investigated and realized. Multifunction and multi-band RF front-end components are promising solutions for reducing the size and enhancing the performance of multi-band communication systems. This dissertation focuses on the design and implementation of different multifunction and tunable microwave components for use in multi-standard, flexible transceiver. For frequency-domain duplexing (FDD) communication systems, in which the uplink and downlink channels are carried on different RF frequencies, a diplexer is an essential component to separate the transmitting and receiving signals from the antenna. Electrically tunable diplexers simplify the architecture of reconfigurable RF-front end. Moreover, in modern communication systems, the crowding of the spectrum and the scaling of electronics can result in higher common-mode interference and even-order non-linearity issues. In this dissertation, three tunable compact SIW-based dual-mode diplexers, with various SE (single-ended) and BAL (balanced) capabilities, are introduced for the first time. The dual-mode operation results in a dependent tuning between the two ports. The presented designs are for SE-SE, SE-BAL, and BAL-BAL. However, based on the presented design concepts, any combination of the diplexer ports can be achieved in terms of supporting the balanced and single-ended system interface. The fabricated diplexers show low insertion loss, high isolation, good tuning range and high common mode rejection. Tunable bandstop filter (BSF) is one of the essential components in the design of RF front-ends that require wide-band operations. A wide-open front-end leaves the receiver vulnerable to jamming by high-power signals. As a result, this type of front-ends requires dynamic isolation of any interfering signal. Realization of such filters in a balanced configuration, as a second function, is an important step in the realization of full-balanced RF front-ends. Balanced (differential) circuits have many important advantages over unbalanced (single-ended) circuits such as immunity to system noise, reduction of transient noise generation and inherent suppression of even-order nonlinearities. All reported balanced filters are bandpass filters that target wide pass-bands and high common-mode rejection. These filters are necessary for wide-band RF front-ends but, as mentioned above, leave the system open to interferers and jammers. In this dissertation, a new differential coupling structure for evanescent-mode cavity resonators is developed, enabling the design of fully-balanced tunable BSF. The proposed filter is tunable from 1.57-3.18 GHz with 102% tuning range. In addition, over the full range, the measured 10-dB fractional bandwidth ranges from 1-2.4%, and the attenuation level is better than 47 dB. Lastly, Substrate Integrated Waveguide (SIW) evanescent-mode cavity resonators (EVA) are employed in the design of RF couplers, quadrature hybrid and rat-race couplers. These couplers are used in the design of numerous RF front-end components such as power amplifiers, balanced mixers, and antenna array feeding networks. Utilizing such resonators (EVA) in the design allows the couplers to have wide spurious-free range, low power consumption, high power handling capability and both tunability and filtering capabilities. The proposed quadrature hybrid coupler can be tuned starting from 1.32–2.22 GHz with a measured insertion loss range from 1.29 to 0.7 dB. The measured reflection and isolation are better than 12 dB and 17 dB, respectively. Moreover, the coupler has a measured spurious free range of 5.1–3fo (lowest–highest frequency). Regarding rat-race coupler, two designs are introduced. The first design is based on a full-mode cavity while the second one is more compact and based on a half-mode cavity. Both designs show more than 70% tuning range, and the isolation is better than 30 dB

LIGA-micromachined tight microwave couplers

There are a significant number of microwave applications, including active antenna arrays, wireless communication systems, navigational applications, etc., where improvement of such qualities as manufacturing costs, size, weight, power consumption, etc. is still on the agenda of today’s RF design. In order to meet these requirements, new technologies must be actively involved in fabrication of RF components with improved characteristics. One of such fabrication technologies is called LIGA, used before primarily in fluidics, photonics, bioengineering, and micromechanics, and only recently receiving growing attention in RF component fabrication. One of the RF components suffering limitations in performance due to limitations in fabrication capabilities is the compact single metal layer (SML) coupled-line 3-dB coupler, also called “hybrid”, required in some applications thanks to its ability to divide power equally and electrically isolate the output from the input. In today’s practical edge-coupled SML coupler designs, the level of coupling is limited by the capabilities of the photolithographic process to print the coupled lines close enough for tight coupling and it is usually no tighter that 8 dB. A promising way to overcome this limitation is increasing the area of metallic interface of the coupled lines, thus increasing the mutual capacitance of the lines, and inherently the coupling between them. This should be preferably done with keeping the coupler compact with respect to the footprint area, which is attained by making taller conductors, i.e. employing the third dimension. In contrast with previously used RF component fabrication processes, LIGA is the technology that allows the designer to explore the third dimension and build tall conductors while being also able to use small features. When the two-dimensional edge-coupled SML couplers are extended into the three-dimensional structures, they rather become the side-coupled SML couplers. Tall-conductor coupled lines have been characterized in this work to reveal their dependence on their geometry and a 3-dB SML coupler with tall conductors has been developed and fabricated using LIGA at the Institute for Microstructure Technology (IMT), Karlsruhe, Germany. The simulation and measurement results demonstrate the potentially superior performance of LIGA couplers, and the promising capabilities of LIGA for fabrication of RF microstructures

Ridge Gap Waveguide Beamforming Components and Antennas for Millimeter-Wave Applications

With the improvement of mobile communication technologies and their broad applications, mobile communication will have more impact on our life. Such systems will support a variety of personal communication services with high-data rate and very low latency applications. To achieve such demands, many proposals associated with the development of 5G identify a set of requirements for which different technological directions are independently emerging. One direction is utilizing the millimeter-wave (mm-Wave) frequency bands where more spectrums are available. Millimeter-wave frequencies offer the advantage of physically smaller components that results in cost-effective RF transceivers and feasible large-scale integrated phased arrays. The smart RF transceivers of 5G along with the potential high-frequency innovative designs must satisfy the growing consumer and technology requirements. This implies utilizing the state-of-the-art guiding structures, especially printed ridge gap waveguide (PRGW), that have low loss and minimal dispersion compared with traditional PCB-based structures. The present chapter focuses on the necessary components for a beamforming antenna system which is implemented using PRGW technology. Millimeter wave antennas with different polarizations have been addressed. Power combining and dividing components have been also developed. These components have been used for integration in a complete beamforming antenna system working at an mm-Wave frequency band

30 GHz Printed Ridge Gap Components and Antennas for Imaging Systems

Working at millimeter waves (MMW) has gained massive attention for wireless communications and imaging systems. For imaging systems, MMW can be used for security to provide good resolution images and detect concealed weapons as it can penetrate common clothes and reflect from the human body and metal objects. Moreover, MMW is safe for human health, contrary to conventional X-ray imaging, which uses an ionized wave. Thus, it has a harmful effect on human health. This research is focusing on building an active wide-view angle millimeter-wave imaging system with a small area of mechanical movement to reduce the data collection time. The imaging system is composed of three main parts: 1) the millimeter-wave components and antennas, 2) the mechanical part for moving the antennas and performing the scan of the imaging area, and 3) the imaging reconstruction algorithm. In order to have an efficient imaging system, the printed ridge gap technology (PRGW) is used to build the imaging system components and antennas. High efficiency coaxial to PRGW transition with a fractional bandwidth of 59.22% at 32.25 GHz is designed to feed the system components. For the transmitting part of the imaging system, a moderate gain PRGW differential feeding planar aperture antenna and a wideband rat-race coupler are designed. The antenna, the rat-race, and the coaxial transition are combined to form the transmitting part, then fabricated and measured. The resulted bandwidth is from 25.62 to 34.34 GHz with a return loss better than 10 dB, a maximum gain of 12.28 dBi, and 3-dB gain bandwidth from 25.62 to 33.77 GHz. For the receiving antenna, a PRGW Butler matrix and its components (directional couplers, 45◦ phase shifters, and crossovers) are designed. A semi-log periodic antenna fed by the PRGW is designed as the radiating element. The PRGW components, the coaxial transition, and the antennas are combined to form the receiving part of the imaging system, which is fabricated and measured. The resulting beam directions are at ±13◦ and ±36◦, at the center frequency (30 GHz). The return loss and the isolations are better than 10 dB over the frequency range from 26.1 to 33.5 GHz. For the imaging reconstruction algorithm, a synthetic aperture radar algorithm is used. Two tests are carried out, one uses CST simulation results, and the other uses measured data from the Concordia antenna chamber lab. The results show an output resolution of 0.6 λ. Finally, the whole imaging system is built with the designed differential feeding antenna as the transmitter, the designed Butler matrix as the receiver, and the synthetic aperture algorithm as the image reconstruction algorithm. The performance network analyzer (PNA) is used to collect the data (s-parameters) required to reconstruct the image, and the antenna range controller system (NSI 5913) is used to mechanically scan the imaging area. The imaging system is used to scan a mannequin carrying an object shaped like a pistol and a knife. The results show that the two objects are detected

Design of Tunable/Reconfigurable and Compact Microwave Devices

With the rapid development of the modern technology, radio frequency and microwave systems are playing more and more important roles. Since the time the first microwave device was invented, they have been leading not only the military but also our daily life to a new era. In order to make the devices have more practical applications, more and more strict requirements have been imposed. For example, good adaptability, reduced cost and shrank size are highly required. In this thesis, three devices are designed based on this requirement. At first, a symmetric four-port microwave varactor based 90-degree directional coupler with tunable coupling ratios and reconfigurable responses is presented. The proposed coupler is designed based on the modified structure of a crossover, where varactors are loaded. Then, a novel reconfigurable 3-dB directional coupler is presented. Varactors and inductors are loaded to the device to realize the reconfigurable performance. By adjusting the voltage applied to the varactors, the proposed coupler can be reconfigured from a branch-line coupler (90-degree coupler) to a rat-race coupler (180 degree coupler) and vice versa. At last, two types (Type-I and Type-II) of microwave baluns with generalized structures are presented. Different from the conventional transmission-line-based baluns where λ/2 transmission lines or λ/4 coupled lines are used, the proposed baluns are constructed by transmission lines with arbitrary electrical lengths

Advances in composite right/left-handed transmission line components, antennas and systems

Résumé Les Métamatériaux (MTMs) électromagnétiques sont des matériaux artificiels qui présentent des propriétés remarquables non disponibles dans les substances naturelles. De récents travaux de recherche et de développement ont permis de démontrer des applications optiques et micro-ondes des MTMs, telles que des lentilles à super-résolution, des dispositifs d'invisibilité, de nouveaux filtres passe-bande, des coupleurs améliorés, des résonateurs et des antennes à ondes de fuite avec de nouvelles propriétés et performances. Avec la capacité à manipuler les ondes électromagnétiques se propageant par l'intermédiaire de leur support, les MTMs électromagnétiques pourraient devenir une clé importante des dispositifs et systèmes optiques, et micro-ondes de l'avenir.Cette thèse présente les dernières avancées des MTMs micro-ondes basés sur le concept des Lignes de Transmission Composites à Main Gauche/Droite (Composite Right/Left-Handed Transmission Line - CRLH TL). Les CRLH TLs sont des structures non-résonantes, constituées de la répétition périodique de série de condensateurs et d'inductances shunt très petits par rapport à la longueur d'onde guidée, qui ont une large bande et de faibles pertes pour les applications micro-ondes. De plus, les CRLH TLs planaires permettent une fabrication à faibles coûts en utilisant la technologie des circuits imprimés et un niveau élevé d'intégration avec les autres composants et systèmes. Ce travail constitue une contribution au développement de nouveaux composants, antennes et systèmes CRLH TL dans trois des classes d'applications spécifiques: onde guidée en régime harmonique, onde guidée en régime d'impulsionnel et onde rayonnée. Dans la première classe, un filtre passe-bande à large bande, un diviseur de puissance en série et des coupleurs à lignes couplées sont élaborés et vérifiés expérimentalement. La deuxième classe comprend un différentiateur et un émetteur à modulation par position d'impulsion. Dans la troisième classe, deux nouveaux concepts de recyclage de puissance améliorant systématiquement l'efficacité de rayonnement des antennes à ondes de fuite (Leaky-Wave Antenna - LWA) sont présentés, numériquement vérifiés par simulation électomagnétique et démontrés expérimentalement. Application de l'onde guidée en régime harmonique Le condensateur interdigital, généralement utilisé dans CRLH TLs, souffre d'une résonance transversale aux fréquences élevées à cause des courants en boucle formés entre ses doigts entrelacés. Cette résonance limite la bande passante des CRLH TLs. Pour cette raison, une nouvelle architecture de la CRLH TL basée sur le concept Métal-Isolant-Métal (MIM) a été proposée, caractérisée, démontrant sa capacité à supprimer complètement cette résonance transversale. La topologie MIM a les avantages d'être symétrique et de petite taille, tout en permettant d'exploiter pleinement la bande passante de la structure.----------Abstract Electromagnetic metamaterials (MTMs) are engineered artificial materials that exhibit unusual properties not available in natural materials. Recent research and development have shown promising optical and microwave applications of MTMs such as super-resolution lenses, cloaking devices, bandpass filter, enhanced couplers, resonators, and leaky-wave antennas with new properties and performance, to name a few. With the ability to manipulate electromagnetic waves propagating through its medium, electromagnetic MTMs are believed to hold an important key to many future optical and microwave devices and systems. This dissertation presents the most recent advances in microwave MTMs based on the Composite Right/Left-Handed (CRLH) transmission line (TL) concept. The CRLH TL based MTMs are non-resonant structures which are constituted of periodic repetition of series capacitors and shunt inductors with a unit cell's size much smaller than the guided wavelength and have favorable broadband and low-loss properties for microwave applications. In addition, planar CRLH TL-based MTMs permit a low-cost fabrication using printed circuit board (PCB) technology and a high level of integration with other microwave components and systems. This work contributes to the development of novel CRLH TL components, antennas and systems in three specific classes of application: harmonic regime guided-wave, impulse regime guided-wave and radiated-wave. In the first class, a wideband bandpass filter, an infinite wavelength series power divider and enhanced coupled-line coupler are developed and verified experimentally. The second class consists of a time differentiator component and a pulse position modulation transmitter system. In the third class, two novel power-recycling concepts to systematically enhance the radiation efficiency of Leaky-Wave Antennas (LWAs) are presented, verified numerically using electromagnetic simulation and demonstrated experimentally. Harmonic regime guided-wave application The interdigital capacitor, generally utilized in CRLH TLs, suffers a transverse resonance at high frequencies due to loop currents forming between adjacent interdigitated fingers. This resonance limits the operating bandwidth of CRLH TL based MTMs. For this reason, an alternative CRLH TL architecture based on Metal-Insulator-Metal (MIM) capacitors was proposed, characterized, and demonstrated to completely suppress the transverse resonance. The MIM based CRLH TL topology has advantages of symmetric design and small size while allows full operating bandwidth. Based on the new architecture, a bandpass filter with tapered coupled resonators was designed and the achieved ultra-wide bandwidth confirms its operation. In addition, an infinite wavelength series power divider using the same MIM based CRLH TL architecture in a stripline configuration was proposed and fabricated

Reactively-loaded non-periodic slow-wave artificial transmission lines for stop band bandwidth enhancement : application to power splitters

This paper presents slow-wave transmission lines based on non-periodic reactive loading. Specifically, the loading elements are stepped impedance shunt stubs (SISS). By sacrificing periodicity using SISS tuned to different frequencies, multiple transmission zeros above the pass band arise, and the rejection level and bandwidth of the stop band is improved as compared with those of periodic structures. Through a proper design, it is possible to achieve compact lines, simultaneously providing the required electrical length and characteristic impedance at the design frequency (dictated by specifications), and efficiently filtering the response at higher frequencies. These lines are applied to the design of a compact power splitter with filtering capability in this work. The length of the splitter, based on a 35.35 Ω impedance inverter, is reduced by a factor of roughly two. Moreover, harmonic suppression better than 20 dB up to the fourth harmonic is achieve

Magneto-Electric Dipole Antenna Arrays

A planar magneto-electric (ME) dipole antenna array is proposed and demonstrated by both full-wave analysis and experiments. The proposed structure leverages the infinite wavelength propagation characteristic of composite right/left-handed (CRLH) transmission lines to form high-gain magnetic radiators combined with radial conventional electric radiators, where the overall structure is excited by a single differential feed. The traveling-wave type nature of the proposed ME-dipole antenna enables the formation of directive arrays with high-gain characteristics and scanning capability. Peak gains of 10.84 dB and 5.73 dB are demonstrated for the electric dipole and magnetic-dipole radiation components, respectively.Comment: 9 pages, 17 figure

Wideband Printed Ridge Gap Rat-Race Coupler for Differential Feeding Antenna

In this paper, a wideband 3 dB hybrid 180° rat-race coupler is introduced in the printed ridge gap waveguide technology. It has simultaneous wide matching and isolation bandwidth with low output amplitude imbalance. It operates in the millimeter wave band from 25.8 to 34.2 GHz (27.96%) with 15 dB return loss and isolation, and ±0.5 dB output amplitude imbalance. The proposed design employing an open stub at the middle of the 3λ/4 branch line and quarter wavelength lines at all the ports of the coupler. The objective of the added open stub is to separate the output ports amplitudes around the -3 dB level by certain values depending on the required amplitude imbalance. The analytical derivation for the role of the added open stub is presented along with a parametric study on its effect on amplitude imbalance, matching, and isolation. This results in having two intersection points for the output ports instead of one of the conventional coupler and hence the amplitude imbalance bandwidth increases. The objective of the added quarter wavelength lines is to improve the matching and isolation bandwidths. First, the conventional rat-race coupler is presented and a bandwidth of 14.25% at 30 GHz is achieved. After that the rat-race with the added quarter wavelength lines is presented to illustrate the objective of the added quarter wavelength lines and a bandwidth of 19.44% is achieved. Finally, the rat-race with the quarter wavelength lines and the added stub is presented and a prototype is fabricated and measured. The s-parameters measurements are in a good agreement with the simulated ones

Branch line couplers with small size and harmonic suppression based on non-periodic step impedance shunt stub (SISS) loaded lines

Altres ajuts: ICREAThis paper presents branch line couplers with compact size and harmonic suppression based on non-periodic reactively loaded artificial lines. The reactive loading elements of the lines are step impedance shunt stubs (SISSs). Such elements provide transmission zeros, which are useful to efficiently suppressing the harmonic content of the device. Moreover, by virtue of reactive loading, the reported artificial lines exhibit a slow wave effect of interest for device miniaturization. The combination of size, harmonic suppression efficiency, and design simplicity (with a clear design methodology) is of interest within the framework of artificial transmission lines and their application to the optimization of microwave passive components