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Search Publications by: Dazhen Gu (Fed)

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Displaying 26 - 50 of 72

Vector-Network-Analyzer Calibration Using Line and Multiple Coplanar-Waveguide Offset Reflects

December 9, 2016
Author(s)
Arkadiusz C. Lewandowski, Wojciech Wiatr, Dazhen Gu, Nate Orloff, Thomas Mitchell (Mitch) Wallis, Pavel Kabos
We present the application of our newly developed multi-reflect-thru technique to vector-network-analyzer calibration in the on-wafer environment. This technique uses a set of highly-reflective one-port devices, referred to as offset-reflects, and a single

Microwave Radiometry of Blackbody Radiation

August 11, 2016
Author(s)
Dazhen Gu
We outline the theoretical formulation of radiometry of the free-space radiation emitted by a blackbody target. Simulation shows a much smaller drop of radiation intensity of a Lambertian source than that of an incoherent source in the near-field region

Development of a NIST WR10 Radiometer

August 10, 2016
Author(s)
Jack T. Surek, Dazhen Gu, Dave K. Walker
— This paper describes the development of a waveguide radiometer to measure noise from millimeter wave electronic components across the full WR10 band from 75 GHz to 110 GHz. DUT noise temperature is estimated based on comparison with room temperature and

SIMULATIONS TO CHARACTERIZE A PASSIVE MICROWAVE BLACKBODY DESIGN

July 29, 2015
Author(s)
Derek A. Houtz, Dave K. Walker, Dazhen Gu
This paper discusses the design of a microwave blackbody to be used as a primary laboratory standard for passive remote sensing applications. The design is required to have excellent performance over the frequencies ranging from 10 GHz to 220 GHz and will

Microwave Measurements and Systematic Circuit-Model Extraction of Nanowire Metal Semiconductor Field Effect Transistors

August 24, 2012
Author(s)
Dazhen Gu, Thomas M. Wallis, Pavel Kabos, Paul T. Blanchard, Kristine A. Bertness, Norman A. Sanford
We present detailed on-wafer scattering parameter measurements and equivalent circuit modeling of metal semiconductor field effect transistor (MESFET) that incorporates a GaN nanowire (NW). A systematic procedure is established to extract intrinsic model

Microwave measurements and systematic circuit-model extraction of nanowire metal semiconductor field-effect transistors

August 24, 2012
Author(s)
Dazhen Gu, Thomas M. Wallis, Pavel Kabos, Paul T. Blanchard, Kristine A. Bertness, Norman A. Sanford
We present detailed on-wafer scattering parameter measurements and equivalent circuit modeling of metal semiconductor field effect transistor (MESFET) that incorporates a GaN nanowire (NW). A systematic procedure is established to extract intrinsic model

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

High Frequency Characterization of Contact Resistance and Conductivity of Platinum Nanowires*

October 1, 2011
Author(s)
Kichul Kim, Paul Rice, Thomas M. Wallis, Dazhen Gu, SangHyun S. Lim, Atif A. Imtiaz, Pavel Kabos, Dejan Filipovic
Abstract— Individual platinum (Pt) nanowires (NWs) with 100 nm and 250 nm diameters, embedded in coplanar waveguide (CPW) structures are investigated. Three approaches for characterization of their contact resistance and conductivity at high frequencies

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

Electrical Characterization of Photoconductive GaN Nanowire Devices from 50 MHz to 33 GHz

July 1, 2011
Author(s)
Thomas M. Wallis, Dazhen Gu, Atif A. Imtiaz, Pavel Kabos, Paul T. Blanchard, Norman A. Sanford, Kristine A. Bertness, Christpher Smith
The electrical response of two-port., photoconductive GaN nanowire devices was measured from 50 MHz to 33 GHz. The admittance of individual contacted nanowires showed an increase on the order of 10% throughout the measured frequency range after exposure to

Deembedding parasitic elements of GaN nanowire MESFETs by use of microwave measurements

June 3, 2011
Author(s)
Dazhen Gu, Thomas M. Wallis, Paul T. Blanchard, SangHyun S. Lim, Atif A. Imtiaz, Kristine A. Bertness, Norman A. Sanford, Pavel Kabos
We present a deembedding roadmap for extracting parasitic elements of a nanowire (NW) MESFET device from full two-port scattering-parameter measurements in the frequency range from 0.1 GHz to 25 GHz. The NW MESFET is integrated in a microwave coplanar

Influence of Periodic Patterning on the Magnetization Response of Micromagnetic Structures

March 29, 2011
Author(s)
SangHyun S. Lim, Thomas M. Wallis, Atif A. Imtiaz, Dazhen Gu, Thomas Cecil, Pavel Kabos, Pavol Krivoski
The magnetization dynamics of a single, patterned, thin-film Permalloy (Ni80Fe20, Py) elements embedded in a coplanar waveguide (CPW) are investigated. The anisotropic magnetoresistance (AMR) effect serves as the detection mechanism in current-modulated