Design and Analysis of a Wide Stopband Microstrip Dual-band Bandpass Filter

A novel configuration of a dual-band bandpass filter (BPF) working as a harmonic attenuator is introduced and fabricated. The proposed filter operates at 3 GHz, for UHF and SHF applications, and 6.3 GHz, for wireless applications. The presented layout has a symmetric structure, which consists of coupled resonators. The designing of the proposed resonator is performed by introducing a new LC equivalent model of coupled lines. To verify the LC model of the coupled lines, the lumped elements are calculated. The introduced filter has a wide stopband up to 85 GHz with 28th harmonic suppression, for the first channel, and 13th harmonic suppression, for the second channel. The harmonics are attenuated using a novel structure. Also, the proposed BPF has a compact size of 0.056 λg2. Having several transmission zeros (TZs) that improve the performance of the presented BPF is another feature. The proposed dual-band BPF is fabricated and measured to verify the design method, where the measurement results confirm the simulations

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

Development of Compact UWB Transmit Receive Modules and Filters on Liquid Crystal Polymer for Radar

This thesis presents the design and development of various microwave components for an airborne snow-probing radar with multi-gigahertz bandwidth and cm-scale vertical resolution. First, a set of ultra-wideband, modular transmit and receive modules with custom power sequencing circuits is presented. These modules were rapid-prototyped as an initial step toward the miniaturization of the radar’s front-end, using a combination of custom and COTS circuits. The transmitter and receiver modules operate in the 2–18 GHz range. Laboratory and field tests are discussed, demonstrating performance that is comparable to previous, connectorized implementations, while accomplishing a 5:1 size reduction. Next, a set of miniaturized band-pass and low-pass filters is developed and demonstrated. This work addressed the lack of COTS circuits with adequate performance in a sufficiently small form factor that is compatible with the planar integration required in a multi-chip module. The filters presented here were designed for manufacture on a multi-layer liquid crystal polymer (LCP) substrate. A detailed trade study to assess the effects of potential manufacturing tolerances is presented. A framework for the automated creation of panelized design variations was developed using CAD tools. Thirty-two design variations with two different types of launches (microstrip and grounded co-planar waveguide) were successfully simulated, fabricated and tested, showing good electrical performance both as individual filters and cascaded to offer outstanding out-of-band rejection. The size of the new filters is 1 cm x 1 cm x 150 μm, a vertical reduction of over 90% and reducing the total cascaded length by over 50%

A Survey of Differential-Fed Microstrip Bandpass Filters: Recent Techniques and Challenges

Differentially driven devices represent a highly promising research field for radio frequency (RF), microwave (MW), and millimeter-wave (mmWave) designers and engineers. Designs employing differential signals are essential elements in low-noise fourth-generation (4G) and fifth-generation (5G) communications. Apart from the conventional planar MW components, differential–fed balanced microstrip filters, as promising alternatives, have several advantages, including high common-mode rejection, low unwanted radiation levels, high noise immunity, and wideband harmonic suppression. In this paper, a comprehensive and in-depth review of the existing research on differential-fed microstrip filter designs are presented and discussed with a focus on recent advances in this research and the challenges facing the researchers. A comparison between different design techniques is presented and discussed in detail to provide the researchers with the advantages and disadvantages of each technique that could be of interest to a specific application. Challenges and future developments of balanced microstrip bandpass filters (BPFs) are also presented in this paper. Balanced filters surveyed include recent single-, dual-, tri-, and wide-band BPFs, which employ different design techniques and accomplish different performances for current and future wireless applications

3-D Printed microwave and tetrahertz passive components

This thesis presents the design of microwave and terahertz filters, fabricated using different types of 3-D printing technology. The work demonstrates the potential of using 3-D printing in the fabrication of microwave and terahertz passive components. The first project introduces a compact coaxial cavity resonator filter which was fabricated using stereolithography 3 D printing process. The size and volume of this filter reduced by almost half, by fitting one resonator inside another resonator. This filter is ideal for fabrication by 3 D printing, as such a complex structure cannot be made easily by other methods. This project demonstrates the advantage of using 3-D printing in fabrication of components with complex structures. The second project introduces three waveguide bandpass filters operating at centre frequency of 90 GHz, which were fabricated using the micro laser sintering process. The filters were the highest frequency metal 3-D printed filters reported at the time of publication. The third project introduces two waveguide filters operating at centre frequency of 180 GHz, which were also fabricated using the micro laser sintering process. These are the world highest frequency waveguide filters fabricated by a metal 3-D printing process. The capability of reproducibility of the micro laser sintering process is also discussed in this thesis. The fourth project introduces a hybrid coaxial bandpass filter with two symmetrical transmission zeros, which was fabricated using stereolithography 3-D printing process. In this project the main-line couplings and input/ output coupling were realized using PCB lines, the idea of using PCB lines instead of coupling irises or probes is to allow different topologies to be designed easily by altering the PCB layout. Finally, the fifth project introduces a terahertz waveguide bandpass filter with embedded H plane waveguide bends. This filter is being fabricated using 3-D screen printing

Design and analysis of wideband passive microwave devices using planar structures

A selected volume of work consisting of 84 published journal papers is presented to demonstrate the contributions made by the author in the last seven years of his work at the University of Queensland in the area of Microwave Engineering. The over-arching theme in the author’s works included in this volume is the engineering of novel passive microwave devices that are key components in the building of any microwave system. The author’s contribution covers innovative designs, design methods and analyses for the following key devices and associated systems: Wideband antennas and associated systems Band-notched and multiband antennas Directional couplers and associated systems Power dividers and associated systems Microwave filters Phase shifters Much of the motivation for the work arose from the desire to contribute to the engineering o

Microwave and Millimeter-wave Miniaturization Techniques, and Their Applications

Miniaturization is an inevitable requirement for modern microwave and mm-wave circuits and systems. With the emerging of high frequency monolithic integrated circuits, it is the passive components’ section that usually occupies the most of the area. As a result, developing creative miniaturization techniques in order to reduce the physical sizes of passive components while keep their high performance characteristics is demanding. On the other hand, it is the application that defines the importance and effectiveness of the miniaturization method. For example, in commercial handset wireless communication systems, it is the portability that primarily dictates miniaturization. However, in case of liquid sensing applications, the required volume of the sample, cost, or other parameters might impose size limitations. In this thesis, various microwave and mm-wave miniaturization methods are introduced. The methods are applied to various passive components and blocks in different applications to better study their effectiveness. Both componentlevel designs and system-level hybrid integration are benefited from the miniaturization methods introduced in this thesis. The proposed methods are also experimentally tested, and the results show promising potential for the proposed methods

Self-Packaged and Low-Loss Suspended Integrated Stripline Filters for Next Generation Systems

The method in which the frequency spectrum is currently allocated is unsustainable. An increasing number of devices are becoming wireless, overcrowding an already crowded spectrum (e.g., the ISM band). Therefore, future systems will be forced to move to higher frequencies in order to be allocated an unused slice of the spectrum and accumulate the desired/required bandwidth. Furthermore, with the continued desire to implement a multitude of sensors on unmanned aerial vehicles (UAVs), as well as the need for conformal small-cell repeaters for 5G communications, next generation systems will have to achieve unprecedented reductions in size, weight, power, and cost (SWaP-C). In order for future systems to become practical, several fundamental technological hurdles must be overcome including the development of low loss and highly integrated components used to build next generation systems. The RF/microwave filter is of particular interest, as it is not only crucial for conditioning the signal for transmission and/or digitization, but can also affect critical system parameters based on it's placement in the system. Due to the increased attenuative nature of the environment at microwave frequencies, the systems dynamic range will have to be maximized requiring an exceptionally low loss filter if placed close to the antenna in the receiver (Rx) chain, which is necessary for defense and adaptive/re-configurable systems. While low loss microwave filtering can be easily achieved using waveguide design techniques, it is much more difficult in a highly integrated planar design due to increased radiation and dielectric losses. A promising solution which minimizes these losses and offers a planar solution is the suspended integrated stripline (SISL) filter. In this research, a low loss fully-board integrated lowpass and highpass filter, using the suspended integrated stripline technology, are designed and studied, pushing the stat-of-the-art in planar filtering technologies. A multi-layer board stack-up, with internally buried hollowed cavities, is used to create the suspended stripline. The embedded filter is accessed through a co-planar waveguide-to-stripline vertical via transition and vice-versa. Simulated and measured results show that insertion losses of less than 1 dB are obtainable including the vertical via transition and associated trace losses. Compared to it's suspended substrate stripline (SSS) predecessor, the SISL filter is one order of magnitude smaller and lighter while achieving identical performance. Beyond the proposed filters, this technological solution can be applied to several other passive microwave components such as couplers, power dividers, and gain equalizers. The capabilities demonstrated in this research will be crucial to the design and integration of modern and next generation systems as it requires no mechanical housing, connectors, or assembly, resulting in a light weight, compact size, and low cost solution

Innovative Microwave and Millimetre-Wave Components and Sub-Systems Based on Substrate Integration Technology

RÉSUMÉ Avec le rapide développement des technologies microondes et millimétriques, les spécifications de conception des circuits et systèmes sont de plus en plus exigeantes. La tendance pour le développement des systèmes de communication se dirige vers un poids minimisé, une taille réduite, de multiples fonctions, une fiabilité accrue et un faible coût. Ainsi, des technologies microondes et millimétriques faibles coûts, performantes et convenant à une production de masse sont critiques pour développer avec succès des systèmes commerciaux. La technologie à guide d’ondes rectangulaire a toujours été parmi les plus populaires pour la fabrication des systèmes millimétriques. Cependant, une difficulté majeure est reliée à leur intégration avec des composants actifs et les autres types de lignes de transmission conventionnelles, telle que microruban ou coplanaire… Les technologies de Circuits Intégrés au Substrat (CISs), incluant la technologie Guide Intégré au Substrat (GIS), qui peut être intégrée dans les substrats diélectriques avec de faibles pertes d’insertion et de radiation, sont une famille de nouvelles structures à ondes guidées. Ces dernières permettent de faire un pont entre les structures planaires et non-planaires. Jusqu’à maintenant, les composants et les sous-systèmes micro-ondes basés sur la technologie GIS ont été largement étudiés et développés. Dans cette thèse, nous étudions d’avantage la technologie GIS afin de proposer et développer divers composants actif et passif micro-ondes et millimétriques innovant et originaux. Ces structures de composants innovants peuvent améliorer l’intégration entre les composants GIS et les autres composants planaires. Ainsi, un certain nombre de structures et composants sont proposés et appliqués dans la conception et la démonstration d’un réseau d’antennes intégré en ondes millimétriques et un sous-système d’antennes intelligentes à 60 GHz. Il est à noter que plusieurs composants étudiés dans ce travail ont été proposés et démontrés à des fréquences micro-ondes plus basses afin de faire une preuve de concept en permettant une fabrication facile des structures et des circuits. Ces circuits en basses fréquences peuvent facilement être adaptés pour des applications aux fréquences plus hautes.---------- ABSTRACT The tendency of modern microwave and millimetre-wave communication system development is towards small size, light weight, reliable, multifunctional and low-cost. Moreover, low-cost, mass producible, high-performance and high-yield microwave and millimetre wave technologies are crucial for developing successful commercial microwave and millimetre wave systems. Rectangular waveguide has always been among the most popular choices for the making of millimetre-wave circuits and systems. A major challenge, however, is related to its integration with active devices and other conventional planar transmission lines, such as microstrip or coplanar waveguide (CPW), etc. Substrate Integrated Circuits (SICs) techniques including substrate integrated waveguide (SIW), which can be integrated in planar dielectric substrate with low insertion loss, high Q and low radiation loss, present a family of novel guided wave structures. This scheme provides a bridge between planar and non-planar structures. Up to now, microwave components and sub-systems based on SIW technology have been widely studied and developed. In this thesis, we take a further study of SIW technology to propose and develop various innovative and original microwave and millimetre-wave passive and active components. These innovative component structures can improve the integration between SIW components and other planar components. Then, a certain number of proposed structures or components are applied in the design and demonstration of millimetre-wave integrated antenna arrays and 60 GHz smart antenna sub-system. Note that many components studied in this work were proposed and demonstrated at different lower microwave frequencies for the proof of concept purpose with easy-to-fabricate structures and circuits. Those low-frequency circuits can easily be scaled up for high-frequency applications

Radar Technology

In this book “Radar Technology”, the chapters are divided into four main topic areas: Topic area 1: “Radar Systems” consists of chapters which treat whole radar systems, environment and target functional chain. Topic area 2: “Radar Applications” shows various applications of radar systems, including meteorological radars, ground penetrating radars and glaciology. Topic area 3: “Radar Functional Chain and Signal Processing” describes several aspects of the radar signal processing. From parameter extraction, target detection over tracking and classification technologies. Topic area 4: “Radar Subsystems and Components” consists of design technology of radar subsystem components like antenna design or waveform design