32 research outputs found

    High-Selectivity Reflectionless Unbalanced-to-Balanced Filtering Power Combiner

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    A high-selectivity reflectionless unbalanced-to-balanced (UTB) filtering power combiner is proposed. The proposed power combiner composes of two absorbing branches, two filtering sections, two transmission lines, a grounded resistor, and a phase inverter. Two transmission zeros respectively located at the lower and upper sides of the passband are achieved by the filtering sections, resulting in high selectivity. The input-port reflectionless response in the bandstop region is obtained by the absorbing branch. A 1.0-GHz UTB filtering power combiner is designed and fabricated. Finally, the measurement performances are given in this paper. The input-reflection absorptive bandwidth and transmission bandwidth are measured as 545 MHz and 132 MHz, respectively. The absorptive bandwidth is 4.12 times the transmission bandwidth

    High-selectivity single-ended and balanced bandpass filters using ring resonators and coupled lines loaded with multiple stubs

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    © 2018 Elsevier GmbH High-selectivity single-ended and balanced bandpass filters (BPFs) using dual-mode ring resonators and coupled lines loaded with multiple stubs are proposed in this paper. With the help of the loaded short-circuited and open-circuited stubs, six deep transmission zeros (TZs) from 0 to 2f0 (f0: center frequency of the passband) can be realized in both of single-ended and balanced BPFs to improve the stopband suppressions. The functions of the loaded short/open stubs and calculated analysis of TZs’ positions have been presented. For further demonstration, two examples of single-ended BPF and balanced BPF with high common-mode suppression are designed and fabricated, whose center frequencies are both at 2.1 GHz. Their measured 3-dB fractional bandwidths are 23.7% and 24.7% (differential-mode), respectively. The simulated results and measurements of these two filters are in good agreement

    Design Methodology for Six-Port Equal/Unequal Quadrature and Rat-Race Couplers With Balanced and Unbalanced Ports Terminated by Arbitrary Resistances

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    For the first time, the 6-port quadrature and rat-race couplers with balanced-unbalanced-hybrid ports are proposed. The corresponding design methodology is presented, which is capable of designing the proposed couplers with arbitrary power divisions and terminated resistances. In this paper, four types including quadrature and rat-race couplers are fully analyzed, covering all the application configurations of the balanced/unbalanced ports. Besides, the design equations are rigorously derived, with the final design procedures presented. Eventually, prototypes of the four coupler types are fabricated and experimentally measured. The final results sufficiently validate the proposed methodology

    Multi-functional and Tunable Microwave Devices and Sub-systems for Wideband Applications

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

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    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

    Compact-Size Wideband Antennas and Arrays for Wireless Communications

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    Polarization is an important parameter for characterizing antenna systems. Dual-polarized and circularly-polarized wideband antennas with compact size are very useful for mobile communications and satellite communications. Due to the multipath propagation and shadowing in urban environment, radio signals received by mobile terminals can become very weak. Dual-polarized antennas can achieve better signal quality in mobile communications by using polarization diversity. Wideband circularly polarized antennas are very important for mobile satellite communications as circularly polarized signals are immune to Faraday rotation effects. Circular polarization also enables mobile satellite communications without strict alignment between transmit and receive antennas. Therefore, dual-polarized antennas and circularly polarized antennas have been drawn increasing popularity in the wireless communication systems. In this thesis, several novel designs of compact, wideband, and specially functioned antennas and arrays are developed for wireless communication applications. First, wideband antennas and arrays are investigated for base station applications with different appealing features, such as compact radiator size, enhanced upper out-of-band suppression, or low pattern sidelobes. They are designed with different novel design concept, such as shared-dipole, electromagnetic dipoles, shorted dipoles, and fourth-order coupling structure. Then, to directly match to the newly emerged differential circuit systems, several wideband differentially fed dual-polarized antennas are proposed for base station applications. They are designed for high common mode suppression, high harmonic suppression, or compact radiator size by using the idea of orthogonal six-port power divider, multi-resonance structure, and crossed open loop resonators. The final designs are two circularly polarized antennas, which have the wide overlapped impedance and axial ratio bandwidth, or dual circularly polarized radiations realized by using crossed open slot-pairs, orthogonal power diver, and phase shift unit cells. The working principles of these different antennas are extensively illustrated with the relevant design theories and detailed structure studies. The performances of these antennas and arrays are evaluated first by the full-wave electromagnetics simulations, and followed by the measurements of the corresponding fabricated prototypes. Good agreements between the simulated and measured results are obtained. With these different features to accommodate different requirements, these antennas and arrays can be the good candidates for the wireless communication systems
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