Integrated Filtering Antennas for Wireless Communications

In traditional radio frequency (RF) front-end subsystems, the passive components, such as antennas, filters, power dividers and duplexers, are separately designed and cascaded via the 50 ? interfaces. This traditional approach results in a bulky and heavy RF front-end subsystem, and suffers from compromised efficiency due to the losses in the interconnections and the mismatching problems between different components. The frequency responses of the antennas such as the frequency selectivity and bandwidth are usually degraded, especially for microstrip antennas. To improve the frequency responses and reduce the size of RF front ends, it is important to investigate novel highly integrated antennas which exhibit multiple functions such as radiation, filtering, power dividing and combining or duplexing, simultaneously. In this thesis, several innovative designs of compact, multi-functional integrated an-tennas/arrays are proposed for wireless communication applications. First, new methods of designing integrated filtering antenna elements with broadband or dual-band performance are investigated. These antennas also feature high frequency selectivity and wideband harmonic suppression. Based on these studies, several integrated filtering array antennas with improved gains and frequency responses are developed for the first time. Compared with traditional array antennas, these proposed antennas exhibit improved bandwidths, out-of-band rejection and wideband harmonic suppression. The application of the filtering antennas in millimeter-wave (mm-Wave) frequency band is also investigated as it can potentially reduce the cost of the mm-Wave front-end subsystems significantly while providing the improved impedance bandwidth. The integrated design techniques are further developed to design novel dual-port highly integrated antennas with filtering and duplexing functions integrated. Such a new concept and the prototypes could find poten-tial applications in wireless communication systems and intelligent transportation system (ITS). In this thesis, comprehensive design methodologies and synthesis methods are provid-ed to guide the design of the integrated filtering antennas. The performance is evaluated with the help of full-wave electromagnetics (EM) simulations. All of the prototypes are fabricated and tested for validating the design concepts. Good agreement between the simulation and measurement results is achieved, demonstrating the integrated antennas have the advantages of compact size, flat gain performance, low losses and excellent harmonic suppression performance. These researches are important for modern wireless communication systems

Analysis and Design of a Substrate Integrated Waveguide Multi-Coupled Resonator Diplexer

A microwave diplexer achieved by coupling a section of a dual-band bandpass filter onto a section of two single-bands (i.e. transmit and receive) bandpass filters is presented. This design eliminates the need for employing external non-resonant junctions in diplexer design, as opposed to the conventional design approach which requires separate non-resonant junctions for energy distribution. The use of separate non-resonant junctions in diplexer design increases the design complexity, as well as gives rise to bulky diplexer devices. The proposed design also removes the too much reliance on the evaluation of suitable characteristic polynomials to achieve a diplexer. Though the evaluation of complex polynomials to achieve a diplexer is seen as a viable option, the technique is hugely dependent on optimisations which come with loads of uncertainties. This thesis relies on well-established design formulations to increase design reliability, as well as simplicity. A 10-pole (10ᵗʰ order) microwave diplexer circuit has been successfully designed, simulated, manufactured and measured. The measured results have been used to validate the circuit model and the electromagnetic (EM) simulated results. The diplexer is composed of 2 poles from a dual-band bandpass filter, 4 poles from a transmit bandpass filter and the remaining 4 poles from a receive bandpass filter. The design was initially implemented using asynchronously tuned microstrip square open-loop resonators. The EM simulation and the measurement results of the microstrip diplexer were presented and show good agreement with the proposed design theory. The design was also implemented using the substrate integrated waveguide (SIW) technique and results presented and discussed. In comparison to the results achieved with the microstrip diplexer, the EM simulation and the measurement results realised with the SIW diplexer, show that a slightly better insertion loss was attained across both the transmit and the receive channels, respectively

Cochlea-Inspired Channelizing Filters for Wideband Radio Systems.

RF and microwave multiplexers with a large number of output ports--called channelizers--have always posed a challenging design problem. Typical multiplexer designs use a set of channel filters connected at either a common port or through a manifold consisting of transmission lines (or waveguide) and tuning elements at the junction of, or between, separate channel filters. Nearly all modern multiplexer design methods rely on optimization of the individual channel filters and/or compensation networks used to reduce channel-to-channel interactions. Even with computer optimization, solutions for certain multiplexer topologies with more than about ten channels are often not possible, especially for units covering a wide bandwidth. The work presented here approaches the problem of designing wide bandwidth, contiguous-channel, multiplexing filters by implementing a model of the mammalian cochlea. The cochlea is an amazing channelizing filter, covering three decades of bandwidth with over 3,000 channels in a very small physical space. Using a simplified mechanical cochlear model and its electrical analogue, a design method is demonstrated for RF and microwave channelizers that retain the desirable features of the cochlea including multiple-octave frequency coverage, a large number of output channels, and an enhanced, high-order upper stop-band response. In addition, improved cochlea-like channelizing filters are demonstrated that use conventional, higher-order bandpass filters with prescribed input impedance characteristics. Versions are presented that cover 20-90 MHz, with both constant fractional bandwidth and constant absolute bandwidth channels, planar microwave channelizers covering 2-7 GHz, and higher-order cochlea-like channelizers covering 200 MHz to 1 GHz. Applications of these channelizing filters include wideband, contiguous-channel receivers for signal intelligence or spectral analysis as well as transmit multiplexing.Ph.D.Electrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/58385/1/cgalbrai_1.pd

Surpassing Fundamental Limits through Time Varying Electromagnetics

Surpassing the fundamental limits that govern all electromagnetic structures, such as reciprocity and the delay-bandwidth-size limit, will have a transformative impact on all applications based on electromagnetic circuits and systems. For instance, violating principles of reciprocity enables non-reciprocal components such as isolators and circulators, which find application in full-duplex wireless radios, radar, biomedical imaging, and quantum computing systems. Overcoming the delay-bandwidth-size limit enables ultra-broadband yet extremely-compact devices whose size is not fundamentally related to the wavelength at the operating frequency. The focus of this dissertation is on using time-variance as a new toolbox to overcome these fundamental limits and re-imagine circuit and system design. Traditional non-reciprocal components are realized using ferrite materials that loose their reciprocity under the application of external magnetic bias. However, the sheer volume, cost and weight of these magnet based non-reciprocal components coupled with their inability to be fabricated in conventional semiconductor processes, have limited their application to bulky and large-scale systems. Other approaches such as active-biased and non-linearity based non-reciprocity are compatible with semiconductor processes, however, they suffer from other poor linearity and noise performance. In this dissertation, using passive transistor switch as the modulating element, we have proposed the concept of spatio-temporal conductivity modulation and have demonstrated a gamut of non-reciprocal devices ranging from gyrators to isolators and circulators. Through novel circuit topologies, for the first time, we have demonstrated on-chip circulators with multi-watt input power handling, operation at high millimeter-wave frequencies, and tailor made circulators for emerging technologies such as simultaneous-transmit-and-receive MRI and quantum computing. Delay-bandwidth-size trade-off is another fundamental electromagnetic limit, that constrains the delay imparted by a medium or a device within a fixed footprint to be inversely proportional to the signal bandwidth. It is this limit that governs the size of any microwave passive devices to be inversely proportional to its operating frequency. As a part of this dissertation, through intelligent clocking of switched capacitor networks we overcame the delay-bandwidth-size limit, thus resulting in infinitesimal, yet broadband microwave devices. Here we proposed a new paradigm in wave propagation where the properties such as the propagation delay and characteristic impedance does not depend on the constituent elements/materials of the medium, but rather heavily rely on the user-defined modulation scheme, thereby opening huge opportunities for realizing highly-reconfigurable passives. Leveraging these concepts, we demonstrated wide range of reciprocal an non-reciprocal devices including ultra-compact delay elements, highly-reconfigurable microwave passives, ultra-wideband circulators with infinitesimal form-factors and dispersion-free chip scale floquet topological insulators. Application of these devices have also been evaluated in real-world systems through our demonstrations of wideband, full-duplex receivers leveraging switched capacitors based true-time-delay interference cancelers and floquet topological insulator based antenna interfaces for full-duplex phased-arrays and ultra-wideband beamformers. Furthermore, to cater the growing RF and microwave needs of future, large-scale quantum computing systems, we demonstrated a low-cryogenic, wideband circulator based on time modulation of superconducting devices. This superconducting circulator is expected to operate alongside the superconducting qubits, inside a dilution refrigerator at 10mK-100mK, thus enabling a tightly integrated quantum system. We also presented the design and implementation of a cryogenic-CMOS clock driver chip that will generate the clocks required by the superconducting circulator. Finally, we also demonstrated the design and implementation of a low-noise, low power consumption, 6GHz - 8GHz cryogenic downconversion receiver at 4K for cryogenic qubit readout

Analysis and Design of Low-Cost Waveguide Filters for Wireless Communications

The area of research of this thesis is built around advanced waveguide filter structures. Waveguide filters and the waveguide technology in general are renowned for high power capacity, low losses and excellent electromagnetic shielding. Waveguide filters are important components in fixed wireless communications as well as in satellite and radar systems. Furthermore, their advantages and utilization become even greater with increase in frequency, which is a trend in modern communication systems because upper frequency bands offer larger channel capacities. However, waveguide filters are relatively bulky and expensive. To comply with more and more demanding miniaturization and cost-cutting requirements, compactness and economical design represent some of the main contemporary focuses of interest. Approaches that are used to achieve this include use of planar inserts to build waveguide discontinuities, additive manufacturing and substrate integration. At the same time, waveguide filters still need to satisfy opposed stringent requirements like small insertion loss, high selectivity and multiband operation. Another difficulty that metal waveguide components face is integration with other circuitry, especially important when solid-state active devices are included. Thus, improvements of interconnections between waveguide and other transmission interfaces are addressed too. The thesis elaborates the following aspects of work: Further analysis and improved explanations regarding advanced waveguide filters with E-plane inserts developed by the Wireless Communications Research Group, using both cross coupled resonators and extracted pole sections (Experiments with higher filter orders, use of tuning screws, degrees of freedom in design, etc. Thorough performance comparison with competing filter technologies) - Proposing novel E-plane filter sections with I-shaped insets - Extension of the E-plane filtering structures with metal fins to new compact dual band filters with high frequency selectivity and miniaturized diplexers. - Introduction of easy-to-build waveguide filters with polymer insert frames and high-performance low-profile cavity filters, taking advantage of enhanced fabrication capabilities when using additive manufacturing - Developing new substrate integrated filters, as well as circuits used to transfer signals between different interfaces Namely, these are substrate integrated waveguide to metal waveguide planar transitions that do not require any modifications of the metal waveguides. Such novel transitions have been designed both for single and orthogonal signal polarizations

Advanced Techniques for the Characterization and Experimental Validation of Passive Inter-Modulation Effect (PIM) in Space Communications Systems

[ES] Los satélites de telecomunicación operan en entornos multiportadora, bajo una demanda continua de mayores capacidades de transmisión. Esto ha originado un aumento en los niveles de potencia de RF, frecuencias de trabajo, y número de canales transmitidos, estimulando la aparición de efectos no lineales de alta potencia, como Multipactor, Corona, y la Intermodulación Pasiva (PIM). Entre los efectos anteriores, el PIM es el menos comprendido, debido a su carácter no lineal y su estrecha relación con la fabricación, lo que dificulta el desarrollo de modelos fiables. Los términos de PIM generados en el enlace descendente pueden interferir a la débil señal en el canal de recepción, amenazando la capacidad de recepción del enlace ascendente. Los modelos tradicionales de PIM suelen basarse en una excitación formada por dos portadoras. Aunque se trata de un caso simple y bastante representativo, presenta diferencias importantes con el escenario real multiportadora. El trabajo de este Ph.D. intenta reducir estas diferencias. Para lograrlo, se realizan dos nuevas contribuciones de relevancia para las condiciones reales de operación de los satélites. En concreto, se ha investigado de forma teórica el rol de las fases de las portadoras en el PIM, y se ha propuesto un nuevo modelo que tiene en cuenta el efecto de las portadoras no contribuyentes en un cierto término de PIM, aplicando un nuevo principio de conservación de energía. Los resultados obtenidos con ambos modelos teóricos se ajustan a los datos experimentales. Debido a la compleja naturaleza del PIM, la validación de los componentes de RF de satélites se realiza mediante tests. Por lo tanto, la disponibilidad de bancos de medida de PIM es un tema de interés para la industria espacial. Sin embargo, el diseño de bancos de altas prestaciones es un desafío, ya que su nivel de PIM debe ser inferior al requerido para validar los dispositivos. Para hardware de satélites, la diferencia entre el nivel de las portadoras a transmitir y la señal de RF a detectar es como 185 dBc. En este Ph.D. se proponen unas nuevas arquitecturas integradas de bancos de PIM en guía de ondas, que cubren tanto el PIM conducido como el radiado. Dichas arquitecturas permiten una reducción importante del nivel de PIM residual del sistema de medida, siendo flexibles, capaces de manejar elevados niveles de potencia, y libres de resonancias e interacciones indeseadas. Los elementos claves de estos bancos son unos multiplexores de bajo PIM, que pueden incorporar dos familias de filtros que admiten un elevado número de ceros de transmisión, y por tanto, son capaces de proporcionar un elevado rechazo en la banda de recepción del PIM. Los bancos de medida de PIM conducido por onda reflejada, sin embargo, están expuestos al PIM generado por la carga empleada para absorber las portadoras de alta potencia. Para resolver esta situación, se han propuesto unas nuevas cargas de bajo PIM, que reducen el PIM residual de estos sistemas de medida. Así mismo, se ha elaborado un nuevo tipo de transición para mitigar el PIM respecto a flanges estándar. Para escenarios radiados se ha desarrollado una formulación capaz de relacionar densidades de potencia en el dispositivo bajo test con los niveles detectados en el banco de medida, y que por tanto permiten trasladar especificaciones de PIM del satélite al sistema de medida. Por último, se han mostrado varias campañas de medida de PIM realizadas con bancos implementados acorde a las nuevas arquitecturas propuestas. Las medidas cubren varias bandas de frecuencia y diferentes escenarios (tanto PIM conducido como radiado). Se ha determinado el excepcional nivel de fondo de ruido de PIM logrado en cada banco. Además, se han mostrado resultados obtenidos para medidas de PIM radiado en capas aislantes multicapa y mallas reflectoras, obteniendo interesantes conclusiones en cuanto a geometrías y impacto que tienen en el PIM elementos como los bordes serrados y los remaches.[CA] Els satèl·lits de telecomunicació operen en entorns multiportadora, sota una demanda contínua de majors capacitats de transmissió. Això ha originat un augment en els nivells de potència de *RF, freqüències de treball, i nombre de canals transmesos, estimulant l'aparició d'efectes no lineals d'alta potència, com *Multipactor, Corona, i la Intermodulació Passiva (*PIM). Entre els efectes anteriors, el *PIM és el menys comprés, a causa del seu caràcter no lineal i la seua estreta relació amb la fabricació, la qual cosa dificulta el desenvolupament de models fiables. Els termes de *PIM generats en l'enllaç descendent poden interferir al feble senyal en el canal de recepció, amenaçant la capacitat de recepció de l'enllaç ascendent. Els models tradicionals de *PIM solen basar-se en una excitació formada per dues portadores. Encara que es tracta d'un cas simple i bastant representatiu, presenta diferències importants amb l'escenari real multiportadora. El treball d'aquest *Ph.D. intenta reduir aquestes diferències. Per a aconseguir-ho, es realitzen dues noves contribucions de rellevància per a les condicions reals d'operació dels satèl·lits . En concret, s'ha investigat de manera teòrica el rol de les fases de les portadores en el *PIM, i s'ha proposat un nou model que té en compte l'efecte de les portadores no contribuents en un cert terme de *PIM, aplicant un nou principi de conservació d'energia. Els resultats obtinguts amb tots dos models teòrics s'ajusten a les dades experimentals. A causa de la complexa naturalesa del *PIM, la validació dels components de *RF de satèl·lits es realitza mitjançant tests. Per tant, la disponibilitat de bancs de mesura de *PIM és un tema d'interés per a la indústria espacial. No obstant això, el disseny de bancs d'altes prestacions és un desafiament, ja que el seu nivell de *PIM ha de ser inferior al requerit per a validar els dispositius. Per a maquinari de satèl·lits , la diferència entre el nivell de les portadores a transmetre i el senyal de *RF a detectar és com 185 *dBc. En aquest *Ph.D. es proposen unes noves arquitectures integrades de bancs de *PIM en guia d'ones, que cobreixen tant el *PIM conduït com el radiat. Aquestes arquitectures permeten una reducció important del nivell de *PIM residual del sistema de mesura, sent flexibles, capaces de manejar elevats nivells de potència, i lliures de ressonàncies i interaccions indesitjades. Els elements claus d'aquests bancs són uns multiplexors de baix *PIM, que poden incorporar dues famílies de filtres que admeten un elevat nombre de zeros de transmissió, i per tant, són capaces de proporcionar un elevat rebuig en la banda de recepció del *PIM. Els bancs de mesura de *PIM conduït per ona reflectida, no obstant això, estan exposats al *PIM generat per la càrrega emprada per a absorbir les portadores d'alta potència. Per a resoldre aquesta situació, s'han proposat unes noves càrregues de baix *PIM, que redueixen el *PIM residual d'aquests sistemes de mesura. Així mateix, s'ha elaborat un nou tipus de transició per a mitigar el *PIM respecte a *flanges estàndard. Per a escenaris radiats s'ha desenvolupat una formulació capaç de relacionar densitats de potència en el dispositiu sota test amb els nivells detectats en el banc de mesura, i que per tant permeten traslladar especificacions de *PIM del satèl·lit al sistema de mesura. Finalment, s'han mostrat diverses campanyes de mesura de *PIM realitzades amb bancs implementats concorde a les noves arquitectures proposades. Les mesures cobreixen diverses bandes de freqüència i diferents escenaris (tant *PIM conduït com radiat). S'ha determinat l'excepcional nivell de fons de soroll de *PIM reeixit en cada banc. A més, s'han mostrat resultats obtinguts per a mesures de *PIM radiat en capes aïllants multicapa i malles reflectores, obtenint interessants conclusions quant a geometries i impacte que tenen en el *PIM elements com les vores serrades i els reblons.[EN] Modern satellite payloads operate in multicarrier scenarios, under a continuous demand for higher capacity links. This leads to an increase in the RF power levels, frequency of operation, and the number of transmitted channels, thus stimulating non-linear high-power effects, such as Multipactor, Corona, thermal issues and Passive Inter-Modulation (PIM). Among the above-mentioned phenomena, PIM is the less studied, or, at least, understood. This is due to its extreme non-linear nature and its close relation to workmanship, which make very difficult the development of models able to faithfully predict and explain PIM degradation. PIM terms, once ignited in the downlink, may interfere the weak signal to be detected in the uplink channel, thus threatening the payload throughput. Traditional PIM models are based on a two-carriers excitation. This is a simple and quite representative case, but has significant differences with the real multi- carrier scenario. This Ph.D. thesis work tries to diminish this gap by two novel contributions of relevance for real operation conditions. Firstly, the role of the carrier phases (neglected for two-carriers excitation) has been theoretically investigated. Secondly, a new model to account for the effect of non-contributing carriers for a given PIM term has been developed, which is based on a novel energy conservation assumption. The resulting models fit to experimental data. Due to the complexity of PIM modeling, PIM validation of RF components is conducted only by testing. The availability of low PIM test set-ups is therefore of great interest for the space industry. However, the design of low PIM test benches is challenging, as their intrinsic residual PIM has to be below the one requested to validate the test devices. For satellite hardware, the dynamic range between the RF power levels of the transmission carriers and the signal to be detected may be 185 dBc. During this Ph.D. thesis work, novel integrated test bed architectures in waveguide technology, both for conducted and radiated PIM scenarios, have been developed. These architectures consent a mitigation of the residual PIM of the test facility, being at the same time flexible, free from unwanted interactions and spurious resonances, and able to withstand considerable RF power levels for the transmission carriers. The key elements of these set-ups are the low PIM multiplexers, which may integrate two new families of waveguide filters able to provide a high number of transmission zeros, and therefore a high rejection, in the PIM reception channel. The test benches conceived for measuring conducted backward PIM, however, are normally unprotected from the PIM generated by the termination absorbing the high-power transmission carriers. To alleviate this situation, a new type of low PIM terminations in waveguide technology has been proposed and verified with PIM tests, showing a clear benefit in mitigating the residual PIM of the test facilities. Moreover, novel transitions able to improve the PIM performance of standard flanges have also been conceived. Finally, and with regard to radiated scenarios, a novel formulation able to convert payload PIM specifications to a practical PIM test is proposed. This formulation consents to link the power flux densities at the device under test (DUT) with the RF power levels measured by the test bench. Last, a large class of PIM measurements carried out with the novel test bed architectures have been reported. These measurements cover several frequency bands (C-, Ku-, K- and Ka) and different PIM scenarios, both conducted and radiated. The exceptional residual PIM noise floor of each test bed will be pointed out. In addition, PIM tests on an anechoic chamber facility, multi-layer insulation blankets (MLIs) and reflector mesh samples are presented, with interesting considerations about the geometry of the structure and the impact on the PIM performance of typical elements as sawing areas and rivets.Smacchia, D. (2022). Advanced Techniques for the Characterization and Experimental Validation of Passive Inter-Modulation Effect (PIM) in Space Communications Systems [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/182402TESI

Fully-Integrated Magnetic-Free Nonreciprocal Components by Breaking Lorentz Reciprocity: from Physics to Applications

Reciprocity is a fundamental physical precept that governs wave propagation in a wide variety of physical domains. The various reciprocity theorems state that the response of a system remains unchanged if the excitation source and the measuring point are interchanged within a medium, and are closely related to the concept of time reversal symmetry in physics. Lorentz reciprocity is a fundamental characteristic of linear, time-invariant electronic and photonic structures with symmetric permittivity and permeability tensors. However, breaking reciprocity enables the realization of nonreciprocal components, such as isolators and circulators, which are critical to electronic, optical and acoustic systems, as well as new functionalities and devices based on novel wave propagation modes. Nonreciprocal components have traditionally relied on magnetic materials such as ferrites that lose reciprocity under the application of an external magnetic field through the Faraday Effect. The need for a magnetic bias limits the applicability of such approaches in small-form-factor Complementary Metal–Oxide–Semiconductor (CMOS)-compatible integrated devices. One of the main features of CMOS technology is the availability of high-speed transistor switches which can be turned ON and OFF, modulating the conductance of the medium. In this dissertation, a novel approach to break Lorentz reciprocity is presented based on staggered commutation in Linear Periodically-Time-Varying (LPTV) circuits. We have demonstrated the world’s first CMOS passive magnetic-free nonreciprocal circulator through spatio-temporal conductivity modulation. Since conductivity in semiconductors can be modulated over a wide range (CMOS transistor ON/OFF conductance ratio at Radio Frequency (RF)/millimeter-wave frequencies is as high as 103-105), commutated LPTV networks break reciprocity within a deeply sub-wavelength form-factor with low loss and high linearity. The resulting nonreciprocal components find application in antenna interfaces of wireless communication systems, connecting the Transmitter (TX) and the Receiver (RX) to a shared antenna. This is particularly important for full-duplex wireless, where the TX and the RX operate simultaneously at the same frequency band and need to be highly isolated in order to maintain receiver sensitivity. Multiple fully-integrated full-duplex receivers are demonstrated in this dissertation that best show the synergy between the physical concept and application-based implementations by using circuit techniques to benefit the system-level performance, such as TX-side linearity enhancement and co-design and co-optimization of the antenna interface and the RX and utilization of the multi-phase structure of our antenna interfaces for analog beamforming in multi-antenna systems. Finally, this dissertation discusses some of the fundamental limits of space-time modulated nonreciprocal structures, as well as new directions to build nonreciprocal components which can ideally be infinitesimal in size. A novel family of inductor-less nonreciprocal components including circulators and isolators have been demonstrated that achieve a wide tuning range in an infinitesimal form-factor. This family of devices combine reciprocal and nonreciprocal modes of operation, through the transfer properties of fundamental and harmonics of the system and enable a wide variety of functionalities

Highly Efficient Planar Antenna System Based on the Planar Waveguide Technology for Low Cost Millimeter-Wave Applications

This thesis investigates the integration of planar antennas, such as Dielectric Resonator Antennas (DRAs) to the planar waveguide structure, specifically the Substrate Integrated Waveguide (SIW) for high radiation efficiency millimeter-wave (mm-wave) applications. The SIW is a low cost and low loss technology, since it almost keeps the guided wave inside the structure. Therefore, it is an excellent candidate feeding scheme compared to traditional planar (multi-conductor) structures, such as the Microstrip Line (MSL) and Co-planar Waveguide (CPW) for many planar antennas. It enhances the antenna’s overall radiation efficiency by minimizing the conduction loss, which dominates at the mm-wave frequency band. For this thesis, two different SIW-integrated DRA configurations operating at mm-wave frequency band are presented. The rectangular DRA is excited in its fundamental mode TEδ11 for radiation through a narrow slot cut on the SIW broad wall. However, the coupling slot itself is excited by the SIW TE10 fundamental mode. In addition, the design guidelines, and a parametric study is also conducted on the proposed antenna parameters to investigate their impact on the antenna’s overall performance including the reflection coefficient and radiation pattern (gain). The results are provided within this thesis. The antenna is made of low cost and low loss materials that are available commercially. It is fabricated by using a novel and simple technique, which is compatible with the Printed Circuit Board (PCB) technology. The board is treated as multi-layers composed of the SIW-layer, and DRA element(s) layer, respectively. The fabricated antenna prototypes are tested to demonstrate their validity for real microwave/mm-wave applications. Their reflection coefficients and radiation patterns are measured, and the antenna shows a boresight gain of 5.51 dB and a radiation efficiency of more than 90 % over the operating frequency band of 33-40 GHz. Antenna arrays based on the SIW integrated DRA are investigated for high gain/radiation efficiency applications. Different array configurations such as, linear (series-fed and corporate-fed) and two-dimensional (2D) arrays are presented. The series-fed DRA array is characterized by a single SIW line loaded by DRA-slot pairs, whereas the SIW-power splitter is used to form the corporate-fed DRA array, when loaded by DRA-slot pairs. While the SIW hybrid-feeding scheme (series-feed combined with corporate-feed) is used to form 2D DRA arrays. In this design, the SIW-power splitter is used to split the power equally and in-phase among the sets (rows) of SIW series fed-DRA elements (columns). A simple and generic Transmission Line (T.L.) circuit model is proposed to simplify and expedite the antenna array design process. It is used to calculate the antenna reflection coefficient and radiation pattern (gain). The T.L. model does not take the mutual coupling between the DRA elements into account, since our study shows that its less than -20 dB over the operating bandwidth. However, it is useful and faster than full-wave solvers, such as HFSS, which consumes time and memory due to the huge generated mesh. The developed T.L. circuit model is used to design the antenna array and study the impact of its main designed parameters on the antenna performance. The developed antenna array T.L. model leads to a general design methodology (guidelines). It also allows for optimum array designs for a given set of performance requirements and to have more physical insight into the SIW technology based antenna systems for mm-wave bands. The designed antenna array samples are fabricated and tested within the operating frequency band 33-40 GHz. The series-fed antenna array shows a measured boresight gain of 11.70 dB, and high radiation efficiency, which is more than 90 % over an operating frequency band of 4%. Furthermore, the measured results are compared to these calculated by the proposed T.L. circuit model and full-wave solver. A good agreement between the measured and the HFSS results are observed, especially near the frequency at which the reflection coefficient is minimum. However, some deviation is noticed between the proposed circuit model and the measured results. This deviation is attributed to the discrete nature of the SIW structure that affects the Short Circuit (SC) performance (magnitude and phase), the T.L. lengths, and the mutual coupling between any two adjacent antenna elements. All these issues are handled efficiently and are taken into account by the full-wave solver. Therefore, the measured reflection coefficient agrees with that of the HFSS, except for a very small deviation, caused by the fabrication tolerances and measurement errors. However, the proposed T.L. circuit model is still valid and can easily predict and estimate the resonance behavior and the impedance bandwidth of the proposed antenna arrays in a very short time compared with the full-wave solver.1 yea

Contribution au développement de tags chipless et des capteurs à codage dans le domaine temporel

La RFID sans puce, en raison du très faible coût des tags, a ouvert une nouvelle voie pour les systèmes d'identification. Les étiquettes RFID sans puce fonctionnant dans le domaine temporel ont l'avantage d'être compatibles avec de grandes distances de lecture, de l'ordre de quelques mètres, et de pouvoir fonctionner dans les bandes de fréquence ISM. Cependant, les tags de ce type développés jusqu'à lors n'offraient qu'une faible capacité de codage. Cette thèse propose une nouvelle méthode pour augmenter la capacité de codage des tags fonctionnant dans le domaine temporel en utilisant des C-sections, c'est-à-dire des lignes de transmission repliées de manière à avoir des zones fortement couplées, ce qui leur donne un caractère dispersif. Une autre approche basée sur une technique multi-couches a également été introduite de façon à augmenter considérablement la capacité de codage. Pour terminer, la preuve de concept d'un tag-capteur d'humidité, basé sur l'utilisation de nano fils de silicium, est également présentée.Chipless RFID tags, owing to their low cost, have opened a new way to the identification systems. Chipless RFID tags operating in the time domain have the advantage of being compatible with large reading distances of the order of a few meters, and also can operate in the ISM frequency bands. However, time domain tags developed until now offer poor coding capacity. This thesis proposes a new method to increase the coding capacity of tags operating in time domain by using C-sections, i.e. the transmission lines are folded so as to have tightly coupled zones that give them a dispersive nature. Another approach based on a multi-layer technique was also introduced, in order to increase the coding capacity considerably. Finally, the proof of concept of a humidity sensor tag based on silicon nanowires is also presented.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

High aspect ratio transmission lines and filters

There are a significant number of microwave applications, where improvement of such qualities as manufacturing costs, size, weight, power consumption, etc. have attracted much research interest. In order to meet these requirements, new technologies can be actively involved in fabrication of microwave components with improved characteristics. One such fabrication technology is called LIGA (a German acronym with an English translation of lithography, electroforming, and moulding) that allows fabrication of high aspect ratio (tall) structures, and only recently is receiving growing attention in microwave component fabrication. The characteristics of high aspect ratio microstrip and coplanar waveguide (CPW) transmission lines are investigated in this thesis. Very low impedance high aspect ratio CPW transmission lines can be realized. A high aspect ratio microstrip folded half wavelength open loop resonator is introduced. Effective configurations for external and bypass gap coupling with open loop resonators are given. Filters with transmission zeros in the stopband, consisting of high aspect ratio single mode open loop resonators are presented to demonstrate the advantages of high aspect ratio structures in realizing lower external quality factors or tight coupling. The transmission zeros are created by novel coupling routings. Some of the filters are fabricated and the filter responses are measured to validate high aspect ratio coupling structures. High aspect ratio diplexers with increased channel isolation are also designed by appropriately combining filters with transmission zeros. A wideband bandpass filter design method, based on the electromagnetic bandgap (EBG) concept is introduced in this thesis. The wideband filters are miniaturized as a result of using the EBG concept in design. An EBG based wideband filter consisting of unit cells that are realized by using high aspect ratio CPW stepped impedance resonators is also presented. The main advantage of this approach is that the high aspect ratio CPW structures make short unit cells practically realizable, resulting in compact filter structure