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Displaying 826 - 850 of 1560

Applications of Artificial Neural Networks to RF and Microwave Measurements

January 1, 2002
Author(s)
Jeffrey Jargon, Kuldip Gupta, Donald C. DeGroot
This article describes how artificial neural networks (ANNs) can be used to benefit a number of RF and microwave measurement areas including vector network analyzer (VNA) calibrations, power, and material characterization. We apply ANNs to model a variety

Magnetic Technology Division: Programs, activities, and accomplishments

January 1, 2002
Author(s)
Ronald B. Goldfarb
The Magnetic Technology Division develops and disseminates unique measurement technology for industries concerned with magnetic information storage and superconductor power. The division's projects are led by senior scientists, often assisted by engineers

Position Dependence in the CDMS II ZIP Detectors

January 1, 2002
Author(s)
V. Madic, W. Rau, D. S. Akerib, P. Brink, B. Cabrera, J. P. Castle, Fengbo Hang, M. B. Crisler, D. Driscoll, J. Emes, R. J. Gaitskell, J. Hellmig, Martin Huber, S. Kamat, John M. Martinis, P. Meunier, T. A. Perera, M. Perillo-Issac, T. Saab, B. Sadoulet, R. W. Schnee, D. N. Seitz, G. Wang, B. A. Young
The Ge and Si detectors developed by the Cryogenic Dark Matter Search (CDMS) II experiment rely on the simultaneous detection of athermal phonons and ionization produced by interactions in the crystal. The athermal phonons provide both the total energy

Radio-Frequency Technology Division: Programs, Activities, and Accomplishments

January 1, 2002
Author(s)
Robert M. Judish, Dennis S. Friday
This book describes the programs in the Radio-Frequency Technology Division, of the National Institute of Standards and Technology. The Radio-Frequency Technology Division is a critical national resource for a wide range of customers. U. S. industry is the

TES Spectrophotometers for Near IR/Optical/UV

January 1, 2002
Author(s)
B. Cabrera, John M. Martinis, Aaron J. Miller, Sae Woo Nam, R. W. Romani
We describe our recent progress on superconducting transition-edge sensor (TES) spectrophotometers in the spectral range from the near infrared through ultraviolet bands. These instruments time-stamp (0.1 υs) and energy-resolve (0.15 eV FWHM) each photon

Transverse compressive stress, fatigue, and magnetic substrate effects on the critical current density of Y-Ba-Cu-O coated RABiTS tapes

January 1, 2002
Author(s)
Najib Cheggour, John (Jack) W. Ekin, Cameron C. Clickner, Ron Feenstra, P Goyal, D F. Paranthaman, D F. Lee, D M. Kroeger, D. K. Christen
The electromechanical properties of (0.3 υm thick) yttrium-barium-copper-oxide (YBCO) coatings on buffered pure-nickel rolling-assisted-biaxially-textured substrates (RABiTS) were measured at 76 K and self magnetic field. YBCO coatings on buffered

Variable mutual inductance in critical-current measurements

January 1, 2002
Author(s)
Loren F. Goodrich, Theodore C. Stauffer
We have investigated the mutual inductance observed on pairs of voltage tapes that are soldered to superconducting wires in order to measure the voltage-current (V-I) characteristics & determine the critical current. Measurements on a Nb-Ti superconductor

Noise Parameter Uncertainties from Monte Carlo Simulations

November 8, 2001
Author(s)
James P. Randa, Wojciech Wiatr
We present results for uncertainties in noise-parameter measurements, obtained using a Monte Carlo simulation of the measurements. Sets of data were generated to simulate measurements on a low-noise amplifier, with given uncertainties in the underlying

A 2.4mm Coaxial Power Standard at NIST

November 1, 2001
Author(s)
Thomas P. Crowley, Fred R. Clague
A microcalorimeter and bolometer transfer standard are used as a national standard for microwave power from 50 MHz to 50 GHz. the microcalorimeter is used to determine the efficiency of the bolometric transfer standards and is similar to an existing Type N

Transmission-line Parameter Approximation for Digital Simulation

November 1, 2001
Author(s)
Dylan Williams, Christopher L. Holloway
This paper compares closed-form approximations for coplanar waveguide and microstrip transmission-line parameters to accurate measurements and full-wave calculations. We suggest improved approximations and demonstrate the limitations of our proposed and

Surface magnetic phase diagram for a semi-infinite ferromagnet

October 12, 2001
Author(s)
Pavel Kabos, David P. Pappas
The phase diagram for the orientation of the surface region is calculated in the parameter space defined by the surface and bulk anisotropy in semi-infinite ferromagnetic systems and in thin ferromagnet films. Surface magnetic canting always occurs when

Government Activity to Increase Benefits from the Global Standards System

October 3, 2001
Author(s)
Roger Marks, Robert E. Hebner
The economic development of the Twentieth Century was accompanied and enhanced by the increasing use of documentary standards, largely developed by industry. In the current environment, companies and nations in global competition adopt various strategies

Dielectric Sleeve Resonator Techniques for Microwave Complex Permittivity Evaluation

October 1, 2001
Author(s)
Richard G. Geyer, Pavel Kabos, James R. Baker-Jarvis
Closed-form analytical solutions are derived for accurate microwave dielectric characterization of rod test specimens inserted into dielectric sleeve resonators placed certrally in a metal cavity. Low-loss sleeve resonators can be used advantageously for

Dynamic Constitutive Relations for Polarization and magnetization

October 1, 2001
Author(s)
James R. Baker-Jarvis, Pavel Kabos
New engineered artificial and metamaterials combine ferroelectrics, ferrites, wires, resonant rings, and ferromagnetic materials to obtain a desired response. In this paper we develop constitute relations for materials where the magnetization and

Noise Characterization of Multiport Amplifiers

October 1, 2001
Author(s)
James P. Randa
I address the issue of the definition and measurement of noise figure and parameters to characterize multiport devices, particularly differential amplifiers. A parameterization in terms of the noise matrix appears to be the most practical. the noise figure

Test-Chamber Imaging Using Spherical Near-Field Scanning

October 1, 2001
Author(s)
Ronald C. Wittmann, Michael H. Francis
Although the theory is straightforward, practical implementation of spherical near-field scanning for evaluating test chambers presents some significant challenges. Among these are the requirement for accurate probe positioning and the difficulty in

Time- and Frequency-Domain Analysis of EMC Test Facilities

October 1, 2001
Author(s)
David R. Novotny, Robert T. Johnk, Claude Weil, Seturnino Canales
We have developed a methodology to determine the quality of an EMC test facility using equipment that may be generally available to RF testing services. By utilizing both, the time- and frequency-domains, an accurate picture of the scattering , and modal
Displaying 826 - 850 of 1560