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Search Publications by: Dazhen Gu (Fed)

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Displaying 1 - 25 of 70

Radio Spectrum Occupancy Measurements Amid COVID-19 Telework and Telehealth

October 14, 2022
Author(s)
Dan Kuester, Xifeng Lu, Dazhen Gu, Azizollah Kord, Jake Rezac, Katie Carson, Marla L. Dowell, Elizabeth Eyeson, Ari Feldman, Keith Forsyth, Vu Le, John Marts, Mike McNulty, Kyle Neubarth, Andre Rosete, Matthew Ryan, Maija Teraslina
During the COVID-19 pandemic, NIST began a targeted campaign of measurements of averaged power and occupancy rate in the radio spectrum. The purpose was to sample real environments to offer timely insights into data infrastructure where it might be

Measurements of IP3 and P1dB for Spectrum Monitoring with Software Defined Radios

March 30, 2022
Author(s)
Mike McNulty, Dazhen Gu, Dan Kuester, Payam Nayeri
This paper discusses methodology for characterizing linearity summary parameters of software-defined radio receivers. First, we introduce a highly automated testbed for 1-dB compression point (P1dB) and third-order input intercept point (IIP3). With this

DEVELOPMENT OF NbN TERAHERTZ HEB MIXERS COUPLED THROUGH SLOT-RING ANTENNAS.

October 12, 2021
Author(s)
Eyal Gerecht, Dazhen Gu, Xin Zhao, John Nicholson, Fernando R. Morales, Sigfrid Yngvessen
In order to improve the power coupling to Phonon-Cooled Hot Electron Bolometric (PHEB)devices, we are experimenting with a different type of antenna. The goal of the project is to eliminate the need for a beam splitter or diplexer and to couple both the

Measurement Challenges for Spectrum Sensing in Communication Networks

April 27, 2021
Author(s)
Dan Kuester, Yao Ma, Dazhen Gu, Adam Wunderlich, Jason Coder, Joseph R. Mruk
We summarize a few key spectrum sensing measurement challenges and recent advances. Laboratory tests of sensing are complicated by their inseparable and often imbedded role in modern hardware. Results are difficult to calibrate because physical parameters

Noise Influence on Scattering-Parameter Measurements

November 4, 2020
Author(s)
Dazhen Gu, Jeffrey A. Jargon, Matthew J. Ryan, Anouk Hubrechsen
We present a general model of noise-influenced scattering (S) parameter measurements performed by a vector network analyzer (VNA). The residual error of the S-parameter due to the noise appears like a complex Gaussian quotient. The statistical analysis of

Digital Radiometer for Traceable Spectrum Sensing

September 14, 2020
Author(s)
Xifeng Lu, Dazhen Gu, Daniel G. Kuester
This paper describes a metrology instrument designed for detecting noise and interference in digital communications. A quadrature detector downconverts in-phase (I) and quadrature (Q) channels, which are each digitized at high speed. This architecture

Blind Measurement of Receiver System Noise

June 5, 2020
Author(s)
Daniel G. Kuester, Adam J. Wunderlich, Duncan A. McGillivray, Dazhen Gu, Audrey Puls
Tightly packaged receive systems pose a challenge for noise measurements. The only available receiver outputs are often user data: link benchmark or diagnostic information that can be scavenged with software. These could include data rate benchmark, self

Noise-Synthesis Technique in Time~Domain for Metrology Application

May 11, 2019
Author(s)
Dazhen Gu, Jeffrey E. Jenkins
We developed a prototype radiometer system to implement the noise-synthesis technique. A solid- state switch synthesizes noise signals from outputs of two synchronized electromechanical switches. The input ports of electromechanical switches are terminated

A Self-Calibrated Transfer Standard for Microwave Calorimetry

July 8, 2018
Author(s)
Dazhen Gu, Xifeng Lu, Ben Jamroz, Dylan Williams, Billy F. Riddle, Xiaohai Cui
We develop a new calibration technique for measuring the correction factor of a calorimeter with a vector network analyzer. Based on a wave-parameter formulation, we develop analytic formulas for the correction-factor ($g$) and effective-efficiency ($\eta$

Thermal Noise Metrology with Time-Based Synthesis

July 8, 2018
Author(s)
Dazhen Gu
We present a new measurement technique of quantifying noise temperature based on temperature and time. A single pole double throw (SPDT) ultra-fast switch combines signal from outputs of two synchronized electromechanical (EM) switches. The input ports of

G-band Reflectivity Results of Conical Blackbody for Radiometer Calibration

January 14, 2018
Author(s)
Derek A. Houtz, Dazhen Gu
Two hollow conical cavities have been developed and built for the National Institute of Standards and Technology (NIST) for use as radiometric brightness temperature sources, or blackbodies. According to Kirchoff's reciprocity relation, a good absorber is

Black Box Measurement of System Noise in Integrated Wireless Receivers

September 13, 2017
Author(s)
Daniel G. Kuester, Duncan A. McGillivray, Sheryl M. Genco, Dazhen Gu
Tightly-integrated antennas and inaccessible radio frequency (RF) outputs are common barriers to measuring system noise in integrated wireless receive systems. We propose a solution centered on locating "SNR isoresponses" --- processed receiver outputs

Efficient Rectangular Waveguide to Stripline Transition in D Band

August 7, 2017
Author(s)
Dazhen Gu, Xifeng Lu, Ronald A. Ginley
We present a waveguide-to-stripline transition for a full {\it D}-band operation from 110 GHz to 170 GHz. An E-plane probe in parallel with waveguide main axis is configured to effectively couple the signal in the primary $\text{TE}_{10}$ mode from the

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