Dominique Cros

Bio: Dominique Cros is an academic researcher from University of Limoges. The author has contributed to research in topics: Resonator & Dielectric. The author has an hindex of 20, co-authored 125 publications receiving 1489 citations. Previous affiliations of Dominique Cros include Centre national de la recherche scientifique.

Low-loss micromachined filters for millimeter-wave communication systems

Abstract: High-performance planar micromachined filters at 37 and 60 GHz are presented. The filters consist of a 3.5% bandwidth two-pole Chebyshev filter with transmission zeros at 37 GHz, 2.7% and 4.3% bandwidth four- and five-pole Chebyshev filters at 60 GHz, and an 8% bandwidth elliptic filter at 60 GHz. Silicon micromachining techniques combined with micropackaging have been applied to allow for very high-Q resonators resulting in low-loss filters. The 37-GHz two-pole filter exhibits a 2.3-dB port-to-port insertion loss. The 2.7% and 4.3% four- and five-pole Chebyshev filters at 60 GHz exhibit 2.8- and 3.4-dB insertion loss, and the 8% elliptic filter exhibits a 1.5-dB insertion loss. These values show a large reduction of insertion loss compared to conventional planar techniques, and can be used for planar low-cost millimeter-wave wireless communication systems.

Whispering gallery dielectric resonator modes for W-band devices

Abstract: The utilization of planar millimeter-wavelength whispering gallery dielectric resonator modes for the design of W-band directional filters and power combiners is studied. The device presented combines the output power of several millimeter-wavelength devices in a single step by means of whispering gallery dielectric resonator (DR) modes. At millimeter wavelengths the cylindrical DRs used on their conventional TE, TM, or hybrid modes are impractically small. When used in their whispering gallery modes (WGMs) these cylindrical DRs have dimensions larger than normal for millimeter wavelength. After a description of the WGM phenomena, both electromagnetic and circuit parameters of these resonators are defined when they are coupled with transmission lines. The analysis based on the ring resonator model makes it possible to predict the theoretical responses of any devices. Experimental results obtained for directional filters and for power combiners in W-band are given. >

Study of whispering gallery modes in anisotropic single-crystal dielectric resonators

Abstract: The Rayleigh-Ritz method and the finite element method nongenerating spurious solutions are employed for analysis of whispering gallery modes (WGMs) in cylindrical single-crystal anisotropic dielectric resonators. These methods allow accurate computation of the resonant frequencies, the Q-factors (depending on the dielectric and on the conductor losses), and the electromagnetic field distributions for all WGMs in the presence of additional elements like metal shields, MIC substrate, or supports. Different families of modes are studied both theoretically and experimentally. The mode coupling phenomenon is investigated. A WGM single-crystal quartz resonator is presented having an unloaded Q-factor greater than 30000 at about 100 GHz, including radiation and dielectric losses. >

Extremely high-Q factor dielectric resonators for millimeter-wave applications

Abstract: It has been proven, based on a rigorous electromagnetic analysis, that spherical TE10p-mode Bragg-reflection resonators exhibit many times higher Q factors than corresponding cylindrical TE01delta-mode dielectric resonators, dielectric whispering-gallery-mode resonators, or empty spherical TE10p-mode cavities. Rigorous equations have been derived that allow optimally designed Q-factor and "quarter-wavelength" reflector-multilayered-spherical Bragg-reflection resonators. Experiments have been performed on three-layer spherical resonators made of single-crystal YAG and single-crystal quartz. The unloaded Q factor for the TE012 mode in these resonators was 1.04times105 at 26.26 GHz for YAG and 6.4times104 at 27.63 GHz for quartz

Rigorous analysis of highly tunable cylindrical transverse magnetic mode re-entrant cavities.

Abstract: Cylindrical re-entrant cavities are unique three-dimensional structures that resonate with their electric and magnetic fields in separate parts of the cavity. To further understand these devices, we undertake rigorous analysis of the properties of the resonance using “in-house” developed Finite Element Method (FEM) software capable of dealing with small gap structures of extreme aspect ratio. Comparisons between the FEM method and experiments are consistent and we illustrate where predictions using established lumped element models work well and where they are limited. With the aid of the modeling we design a highly tunable cavity that can be tuned from 2 GHz to 22 GHz just by inserting a post into a fixed dimensioned cylindrical cavity. We show this is possible, as the mode structure transforms from a re-entrant mode during the tuning process to a standard cylindrical transverse magnetic mode.

Microstrip filters for RF/microwave applications

Abstract: Preface to the Second Edition. Preface to the First Edition. 1 Introduction. 2 Network Analysis. 2.1 Network Variables. 2.2 Scattering Parameters. 2.3 Short-Circuit Admittance Parameters. 2.4 Open-Circuit Impedance Parameters. 2.5 ABCD Parameters. 2.6 Transmission-Line Networks. 2.7 Network Connections. 2.8 Network Parameter Conversions. 2.9 Symmetrical Network Analysis. 2.10 Multiport Networks. 2.11 Equivalent and Dual Network. 2.12 Multimode Networks. 3 Basic Concepts and Theories of Filters. 3.1 Transfer Functions. 3.2 Lowpass Prototype Filters and Elements. 3.3 Frequency and Element Transformations. 3.4 Immittance Inverters. 3.5 Richards' Transformation and Kuroda Identities. 3.6 Dissipation and Unloaded Quality Factor. 4 Transmission Lines and Components. 4.1 Microstrip Lines. 4.2 Coupled Lines. 4.3 Discontinuities and Components. 4.4 Other Types of Microstrip Lines. 4.5 Coplanar Waveguide (CPW). 4.6 Slotlines. 5 Lowpass and Bandpass Filters. 5.1 Lowpass Filters. 5.2 Bandpass Filters. 6 Highpass and Bandstop Filters. 6.1 Highpass Filters. 6.2 Bandstop Filters. 7 Coupled-Resonator Circuits. 7.1 General Coupling Matrix for Coupled-Resonator Filters. 7.2 General Theory of Couplings. 7.3 General Formulation for Extracting Coupling Coefficient k. 7.4 Formulation for Extracting External Quality Factor Qe. 7.5 Numerical Examples. 7.6 General Coupling Matrix Including Source and Load. 8 CAD for Low-Cost and High-Volume Production. 8.1 Computer-Aided Design (CAD) Tools. 8.2 Computer-Aided Analysis (CAA). 8.3 Filter Synthesis by Optimization. 8.4 CAD Examples. 9 Advanced RF/Microwave Filters. 9.1 Selective Filters with a Single Pair of Transmission Zeros. 9.2 Cascaded Quadruplet (CQ) Filters. 9.3 Trisection and Cascaded Trisection (CT) Filters. 9.4 Advanced Filters with Transmission-Line Inserted Inverters. 9.5 Linear-Phase Filters. 9.6 Extracted Pole Filters. 9.7 Canonical Filters. 9.8 Multiband Filters. 10 Compact Filters and Filter Miniaturization. 10.1 Miniature Open-Loop and Hairpin Resonator Filters. 10.2 Slow-Wave Resonator Filters. 10.3 Miniature Dual-Mode Resonator Filters. 10.4 Lumped-Element Filters. 10.5 Miniature Filters Using High Dielectric-Constant Substrates. 10.6 Multilayer Filters. 11 Superconducting Filters. 11.1 High-Temperature Superconducting (HTS) Materials. 11.2 HTS Filters for Mobile Communications. 11.3 HTS Filters for Satellite Communications. 11.4 HTS Filters for Radio Astronomy and Radar. 11.5 High-Power HTS Filters. 11.6 Cryogenic Package. 12 Ultra-Wideband (UWB) Filters. 12.1 UWB Filters with Short-Circuited Stubs. 12.2 UWB-Coupled Resonator Filters. 12.3 Quasilumped Element UWB Filters. 12.4 UWB Filters Using Cascaded Miniature High- And Lowpass Filters. 12.5 UWB Filters with Notch Band(s). 13 Tunable and Reconfigurable Filters. 13.1 Tunable Combline Filters. 13.2 Tunable Open-Loop Filters without Via-Hole Grounding. 13.3 Reconfigurable Dual-Mode Bandpass Filters. 13.4 Wideband Filters with Reconfigurable Bandwidth. 13.5 Reconfigurable UWB Filters. 13.6 RF MEMS Reconfigurable Filters. 13.7 Piezoelectric Transducer Tunable Filters. 13.8 Ferroelectric Tunable Filters. Appendix: Useful Constants and Data. A.1 Physical Constants. A.2 Conductivity of Metals at 25 C (298K). A.3 Electical Resistivity rho in 10-8 m of Metals. A.4 Properties of Dielectric Substrates. Index.

A Survey on Gas Sensing Technology

Abstract: Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sensitivity and selectivity for performance indicators to compare different sensing technologies, analyzes the factors that influence these two indicators, and lists several corresponding improved approaches.

Advanced coupling matrix synthesis techniques for microwave filters

Abstract: A general method is presented for the synthesis of the folded-configuration coupling matrix for Chebyshev or other filtering functions of the most general kind, including the fully canonical case, i.e., N prescribed finite-position transmission zeros in an Nth-degree network. The method is based on the "N+2" transversal network coupling matrix, which is able to accommodate multiple input/output couplings, as well as the direct source-load coupling needed for the fully canonical cases. Firstly, the direct method for building up the coupling matrix for the transversal network is described. A simple non-optimization process is then outlined for the conversion of the transversal matrix to the equivalent "N+2" folded-configuration coupling matrix. The folded matrix may be used directly to realize microwave bandpass filters in a variety of technologies, but some of these could require awkward-to-realize cross-couplings. This paper concludes with a description of two simple procedures for transforming the transversal and folded matrices into two novel network configurations, which enable the realization of advanced microwave bandpass filters without the need for complex inter-resonator coupling elements.

Optical resonators with whispering-gallery modes-part I: basics

Abstract: We briefly review basic properties of dielectric whispering gallery mode resonators that are important for applications of the resonators in optics and photonics.

Micromachined devices for wireless communications

Abstract: An overview of recent progress in the research and development of micromachined devices for use in wireless communication subsystems is presented. Among the specific devices described are tunable micromachined capacitors, integrated high-Q inductors, micromachined low-loss microwave and millimeter-wave filters, low-loss micromechanical switches, microscale vibrating mechanical resonators with Q's in the tens of thousands, and miniature antennas for millimeter-wave applications. Specific applications are reviewed for each of these components with emphasis on methods for miniaturization and performance enhancement of existing and further wireless transceivers.