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Displaying 26 - 50 of 190

Verification of Noise-Parameter Measurements and Uncertainties

November 1, 2011
Author(s)
James P. Randa, Dazhen Gu, Dave K. Walker
We propose and implement verification methods for measurements of noise parameters of amplifiers and transistors. Because the verification rests on the comparison of different measurement results, it also serves as a test of the uncertainties. The

Reflectivity Study of Microwave Blackbody Targets

September 1, 2011
Author(s)
Dazhen Gu, Derek A. Houtz, James P. Randa, Dave K. Walker
We report on the characterization of blackbody target reflections as part of the recent progress on the development of brightness temperature standards for microwave remote sensing at the National Institute of Standards and Technology (NIST). The very low

Noise-Parameter Measurements with a Reflection Type Phase Shifter

November 1, 2010
Author(s)
Dazhen Gu, Dave K. Walker, James P. Randa
We report a miniaturized phase shifter operating in the frequency range from 5 GHz to 7 GHz for noise-parameter extraction. Such a tunable solid-state unit represents a significant reduction in the size and mass as a source-pull component, compared to its

Thermal Noise and Noise Measurements a 2010 Update

October 1, 2010
Author(s)
Anthony R. Kerr, James P. Randa
1. Introduction 2. Noise Temperature as a Measure of Noise Power 3. Available Noise Power from a Resistor 4. The Zero-Point Noise Term and the Minimum Noise of an Amplifier 5. Noise-Temperature Standards and Measurement of One-Port Noise Sources 6

Comparison of Microwave Black-Body Target Radiometric Measurements

July 30, 2010
Author(s)
Dave K. Walker, Dazhen Gu, Katherine MacReynolds, Randy Direen, James P. Randa, Amanda Cox, Derek A. Houtz, Robert L. Billinger
Accurate characterization of the brightness temperature (T_B) of black-body targets used for calibrating microwave remote-sensing radiometers includes many inputs: antenna pattern and loss, target temperature, target emissivity, mechanical alignment, and

REFLECTIVITY STUDIES OF PASSIVE MICROWAVE CALIBRATION TARGETS AND ABSORPTIVE MATERIALS

July 30, 2010
Author(s)
Dazhen Gu, Amanda Cox, Derek A. Houtz, Dave K. Walker, James P. Randa, Robert L. Billinger
We report the characterization of blackbody reflections as a part of the recent progress on the development of brightness standards for microwave remote sensing at National Institute of Standards and Technology (NIST).Three blackbody targets at variable

Simulator for Amplifier and Transistor Noise-Parameter Measurements

June 18, 2010
Author(s)
James P. Randa
This paper describes a simulation program that was developed to compare the uncertainties that would be expected with different measurement strategies for the noise parameters of connectorized amplifiers and of amplifiers or transistors on wafers. Both

CCEM.RF-K4.CL Comparison RF-Voltage measurements up to 1 GHz

May 20, 2010
Author(s)
James P. Randa, Jan P. de Vreede
We report the results of an international comparison of measurements of radio frequency voltage in the frequency range 1 MHz to 1 GHz. This comparison was performed as a Key Comparison under the auspices of the Consultative Committee for Electricity and

Uncertainty Analysis for Noise-Parameter Measurements at NIST

April 9, 2009
Author(s)
James P. Randa
The uncertainty analysis is presented for NIST measurements of noise parameters of amplifiers and transistors, in both connectorized (coaxial) and on-wafer environments. We treat both the X-parameters, which are based on the wave representation of the

Variable Termination Unit for Noise-Parameter Measurements

April 1, 2009
Author(s)
Dazhen Gu, Dave K. Walker, James P. Randa
NIST has upgraded its measurement capability of noise parameters on low-noise amplifiers with a variable termination unit (VTU) in the 1 to 12.4 GHz frequency range. Such a unit allows improved time efficiency and accuracy in the noise-temperature

Recommended Terminology For Microwave Radiometry

August 1, 2008
Author(s)
James P. Randa, Janne Lahtinen, Adriano Camps, A. Gasiewski, Martti Hallikainen, David Leine V, Manuel Martin-Neira, Jeff Piepmeier, Philip Rosenkranz, Christopher Ruf, James Shiue, Niels Skou
We present recommended definitions for common terms in microwave remote-sensing radiometry. Terms are grouped into three chapters: General Terminology, Real-Aperture Radiometers, and Polarimetric Radiometry. AN alphabetical index lists the terms that are
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