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Microwave Devices (microwave + device)

Distribution by Scientific Domains
Engineering58%
Polymers and Materials Science25%
Chemistry16%

Selected Abstracts

Ba-Hexaferrite Films for Next Generation Microwave Devices

CHEMINFORM, Issue 37 2006
V. G. Harris
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Multimode Microwave Reactor for Heterogeneous Gas-Phase Catalysis

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2003
H. Will
In order to investigate heterogeneously catalyzed gas-phase reactions, e.g. the oxidation of propane, on heterogeneous catalysts in the multimode microwave field, a microwave device was modified to achieve an adequate field homogeneity and a continuous power control. To date, no similar apparatus has been described in the literature. The presented microwave apparatus is suitable for carrying out reproducible catalytic investigations in the multimode microwave field. [source]

Giant Electric Field Tuning of Magnetism in Novel Multiferroic FeGaB/Lead Zinc Niobate,Lead Titanate (PZN-PT) Heterostructures

ADVANCED MATERIALS, Issue 46 2009
Jing Lou
A novel multiferroic heterostructure consisting of a FeGaB thin film and a PZN-PT single crystal slab shows giant tunability of the ferromagnetic resonance (FMR) frequency of the heterostructure by electric field (see figure). The overall electric-field-induced FMR frequency change of 5.82 GHz is the largest reported so far. FeGaB/PZN-PT multiferroic heterostructures are promising candidates for wide-band electrostatically tunable microwave devices. [source]

Modeling of microwave devices with space mapping and radial basis functions

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 3 2008
Slawomir Koziel
Abstract We review recent developments in space mapping techniques for modeling of microwave devices. We present a surrogate modeling methodology that utilizes space mapping combined with radial basis function interpolation. The method has advantages both over the standard space mapping modeling methodology and the recently published space mapping modeling with variable weight coefficients. In particular, it provides accuracy comparable or better than the latter method and computational efficiency as good as the standard space mapping modeling procedure. A comparison between the space mapping modeling methodologies as well as application examples of optimization and statistical analysis of microwave structures is presented. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Model order reduction of linear and nonlinear 3D thermal finite-element description of microwave devices for circuit analysis

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2005
Raphaël Sommet
Abstract Electrothermal models of power devices are necessary for the accurate analysis of their performances. For this reason, this article deals with a methodology to obtain an electrothermal model based on a reduced model of a 3D thermal finite-element (FE) description for its thermal part and on pulsed electrical measurements for its electrical part. The reduced thermal model is based on the Ritz vector approach, which ensures a steady-state solution in every case. An equivalent SPICE subcircuit implementation for circuit simulation is proposed and discussed. An extension of the method to a nonlinear reduced model based on the Kirchoff transformation is also proposed. The complete models have been successfully implemented in circuit simulators for several HBT or PHEMT device structures. Many results concerning devices and circuits are presented, including simulation of both the static and dynamic collector-current collapse in HBTs due to the thermal phenomenon. Moreover, the results in terms of the circuit for an X-band high-power amplifier are also presented. As for the nonlinear approach, results concerning an homogeneous structure is given. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source]

Noise in lossless microwave multiports

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2004
Q. García-García
Abstract This article addresses the noise behaviour (noise temperature and noise figure) of some passive microwave multiport circuits. The analysis method is based on the noise-wave formulation. With the exception of the attenuator case, which is used as a reference, the circuit elements considered are lossless devices, in the sense that neither conductive nor dielectric losses are accounted for. The analysis shows that, when connected to matched loads in some of their ports, these multiports circuits lose their lossless nature and their scattering matrix is not unitary; therefore, they generate thermal noise. The article addresses and formalizes mathematically the noise properties of a number of lossless microwave devices such as N -port power splitters, circulators, and hybrid couplers. While the noise-wave mathematical formulation may be cumbersome in some cases, all the devices and configurations analyzed in this work have been characterized in terms of noise figure and noise temperature, which is a much more practical approach in most situations. Some implications of the use of these devices and configurations in antenna arrays for antenna noise temperature evaluations have been also addressed. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 99,110, 2004. [source]

Direct optical-to-microwave domain conversion

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2006
M. Haridim
Abstract A novel method for direct conversion of optical signals into microwave signals is proposed. This method is based on the optical controlling of microwave devices. The feasibility of the proposed method is experimentally proved for a microstrip line implemented on Si substrate. We present experimental results for conversion of on-off keying (OOK) optical signals to binary amplitude-shift keying (ASK) microwave signals. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 320,322, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21337 [source]

Application of ferromagnetic composite in different planar tunable microwave devices

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2001
E. Salahun
Abstract In this paper, several microwave devices using a ferromagnetic composite demonstrate great tunability under weak magnetizing field conditions. Indeed, a tunable bandstop of 50% tunability and phase shifters of 35°/dB figure of merit around 3 GHz and 7.8°/dB in the X -band are obtained when a 250 Oe dc magnetic field is applied. Moreover, a magnetic switch near 25 dB isolation and less than 1 dB insertion losses is realized. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 272,276, 2001. [source]

Polymeric composites for use in electronic and microwave devices

POLYMER ENGINEERING & SCIENCE, Issue 3 2004
Alexandre Moulart
The dielectric and conductive properties of thermoplastic (ABS) composites filled with ceramic powder (barium titanate), conductive powders (carbon black, copper) and conductive fibers (carbon, steel) were investigated for use in electromagnetic crystals and microwave devices. Barium titanate/ABS composites were produced that had dielectric constants over 8 and loss tangents of 0.01, which are the requirements for electromagnetic crystals. Carbon black/ABS and steel fiber/ABS composites were obtained with conductivities suitable for electromagnetic shielding (over 10,3 S/cm). Fused decomposition modeling was tested as a method for building electromagnetic crystals and showed promising results. Polym. Eng. Sci. 44:588,597, 2004. © 2004 Society of Plastics Engineers. [source]