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Displaying 676 - 700 of 1560

Checks of Amplifier Noise-Parameter Measurements

June 11, 2004
Author(s)
James P. Randa, Dave K. Walker
We propose two verification methods for measurements of noise parameters of amplifiers, particularly low-noise amplifiers (LNAs). One method is a direct measurement of the parameter Trev, the noise temperature from the amplifier input, and the comparison

Extended NVNA Bandwidth for Long-Term Memory Measurements

June 11, 2004
Author(s)
Catherine A. Remley, Dominique Schreurs, Dylan F. Williams, John Wood
We present a new technique for measuring the magnitude and phase of intermodulation products outside the measurement bandwidth of our instrumentation. We apply the technique to measurements of long-term memory effects, and realte our measurements to

Non-Linear Large-Signal Scattering Parameters: Theory and Applications

June 11, 2004
Author(s)
Jeffrey Jargon, Kuldip Gupta, Donald C. DeGroot
We introduce nonlinear large-signal scattering parameters, a new type of frequency-domain mapping that relates incident and reflected signals for sparse-tone inputs. We present a general form of nonlinear large-signal scattering parameters and show that

Radiometer Measurements of a Near-Ambient, Variable-Temperature Noise Standard

June 7, 2004
Author(s)
George Free, James P. Randa, Robert L. Billinger
A near-ambient, variable-temperature noise standard whose physical temperature can be accurately measured was constructed and then measured with the NIST total-power radiometer to test the accuracy of radiometer measurements in the temperature range of 263

A study of magnetic interactions of Ni80Fe20 arrays using ultra-sensitive microcantilever torque magnetometry

June 1, 2004
Author(s)
Lan Gao, D. Q. Feng, L. Yuan, T. Yokota, R. Sabirianov, Sy-Hwang Liou, Michelle Chabot, Daniel Porpora, John M. Moreland
We have successfully fabricated single and paired 300 nm × 1.5 υm × 32 nm Ni 80Fe 20 bars on a microcantilever using focused ion beam milling. Magnetic interactions of these paired bars were studied by using magnetic force microscopy, microcantilever

Traceability for microwave remote-sensing radiometry

June 1, 2004
Author(s)
James P. Randa
A plan is presented for developing a standard for brightness temperature at microwave frequencies, as well as two different methods for transferring this standard to the microwave remote-sensing community. The standard will be based on existing NIST

Pulse Parameter Dependence on Transition Position and Epoch Duration

May 18, 2004
Author(s)
Donald R. Larson, Nicholas Paulter, David I. Bergman
The pulse parameters of amplitudes and transition duration (10% to 90%) are examined as a function of the epoch and position of the transition edge in the epoch. The primary explanations for the observed variations are the pulse aberrations and the finite

'Across-the-Road Photo Traffic Radars: New Calibration Techniques'

May 17, 2004
Author(s)
Claude Weil, Dennis G. Camell, David R. Novotny, Robert T. Johnk
We discuss simulator units for calibrating across-the-road Doppler traffic radar transceivers used in enforcement of highway speed limits. Two units of very similar design were developed, one operating at K-band (24 GHz) and the other at Ka-band (35 GHz)

Microfabricated alkali atom vapor cells

April 5, 2004
Author(s)
Li-Anne Liew, Svenja A. Knappe, John M. Moreland, Hugh Robinson, David C. Larbalestier, John Kitching
We describe the fabrication of chip-sized alkali atom vapor cells using silicon micromachining and anodic bonding technology. Such cells may find use in highly miniaturized atomic frequency references or magnetometers. The cells consist of cavities etched

Micromachined Alkali Atom Vapor Cells for Chip-Scale Atomic Clocks

January 30, 2004
Author(s)
Li-Anne Liew, Svenja A. Knappe, John M. Moreland, Hugh Robinson, Leo W. Hollberg, John Kitching
This paper describes the fabrication of chip-sized alkali atom vapor cells, for use in highly miniaturized atomic frequency references, using silicon micromachining and anodic bonding technology. The cells consist of silicon cavities with internal volume

Direct-Current Induced Dynamics in Co 90 Fe 10 /Ni 80 Fe 20 Point Contacts

January 16, 2004
Author(s)
William Rippard, Matthew Pufall, Shehzaad F. Kaka, Stephen E. Russek, Thomas J. Silva
We have directly measured coherent high-frequency magnetization dynamics in ferromagnetic films induced by a spin-polarized dc current. The precision frequency can be tuned over a range of several gigahertz by varying the applied current. The frequencies

DC Conductivity Measurements of Metals

January 1, 2004
Author(s)
Michael D. Janezic, Raian K. Kaiser, James R. Baker-Jarvis, George Free
In this paper we examine a measurement method for characterizing the dc conductivity of metal alloys commonly-used in hand weapons. From accurate measurements of the voltage and current across a cylindrical metal sample, we calculate the metal's dc

Measurement of Hydrogen in Metal Alloys by Magnetic and Electronic Techniques

January 1, 2004
Author(s)
P. Termsuksawad, S. Niyomsoan, Ronald B. Goldfarb, V I. Kaydanov, David Olson, B. Mishra, Z Gavra
As demonstrated in this paper, magnetic and electronic measurements can be used to quantify hydrogen availability, absorption, and desorption in materials for nickel metal-hydride batteries and hydrogen storage. The ability of a metal alloy to absorb and

Surface magnetic canting in a nonuniform film

January 1, 2004
Author(s)
M G. Pini, A Retlori, David P. Pappas, A. V. Anisimov, Alexander Popov
The zero temperature equilibrium configuration of a nonuniform system made of a ferromagnetic (FM) monolayer on top of a semi-infinite FM film is calculated using a nonlinear mapping formulation of mean-field theory, where the surface is taken into account
Displaying 676 - 700 of 1560