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Search Publications by: John Ladbury (Fed)

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Displaying 1 - 25 of 77

Characterizing LTE User Equipment Emissions Under Closed-Loop Power Control

April 6, 2021
Author(s)
Jason Coder, Aric Sanders, Michael R. Frey, Adam Wunderlich, Azizollah Kord, Jolene Splett, Lucas N. Koepke, Daniel Kuester, Duncan McGillivray, John M. Ladbury
This report presents a laboratory-based characterization of Long Term Evolution (LTE) User Equipment (UE) emissions under closed-loop power control, building on our prior work (NIST TN 2069), which assessed the impact of a large number of factors affecting

Characterizing LTE User Equipment Emissions: Factor Screening

September 30, 2019
Author(s)
Jason Coder, Adam Wunderlich, Michael R. Frey, Paul T. Blanchard, Dan Kuester, Azizollah Kord, Max Lees, Aric Sanders, Jolene Splett, Lucas N. Koepke, Rob Horansky, Duncan McGillivray, John M. Ladbury, Jeffrey T. Correia, Venkatesh Ramaswamy, Jerediah Fevold, Shawn Lefebre, Jacob K. Johnson, John Carpenter, Mark Lofquist, Keith Hartley, Melissa Midzor
Characterizations of long-term evolution (LTE) user equipment (UE) emissions are a key ingredient in models of interference between wireless cellular networks and other systems that must use the same radio frequency spectrum. This report presents (i) a

LTE Handset Emissions: Radiation Pattern Measurements Final Test Report

August 16, 2019
Author(s)
Robert D. Horansky, Jason B. Coder, John M. Ladbury
The Defense Information Systems Agency (DISA) Defense Spectrum Organization (DSO) throughthe Spectrum Sharing Test and Development (SSTD) program proposed a National AdvancedSpectrum and Communications Test Network (NASCTN) measurement campaign to

Carbon Nanotube Thin Film Patch Antennas for Wireless Communications

May 24, 2019
Author(s)
E. A. Bengio, Damir Senic, Lauren W. Taylor, Robert J. Headrick, Michael King, Peiyu Chen, Charles A. Little, John M. Ladbury, Chris Long, Christopher L. Holloway, Aydin Babakhani, James Booth, Nate Orloff
Early work on carbon nanotube (CNT) antennas indicated that their performance could not match that of metals such as copper. However, recent improvements in fluid phase CNT processing have yielded macroscopic CNT materials with better alignment and

EMC and Metrology Challenges for 5G and Beyond

December 7, 2018
Author(s)
Perry F. Wilson, Catherine A. Remley, William F. Young, Camillo A. Gentile, John M. Ladbury, Dylan F. Williams
The potential to connect people and devices anywhere and anytime is driving the development and deployment of a multitude of wireless systems. Wireless connectivity is central to advanced communication technologies, the internet of things (IoT), the smart

Measured Emission Spectra of Selected AWS-3 LTE Transmitters

January 16, 2018
Author(s)
Michael R. Frey, Geoffrey Sanders, Jolene Splett, John M. Ladbury, Frank Sanders, Azizollah Kord, Ryan T. Jacobs
Version three of Advanced Wireless Services (AWS-3) radio systems will soon use spectrum that is adjacent to bands currently used by airborne telemetry links at U.S. government test and training ranges (TTRs). It is possible that out-of-band (OoB) and

Equivalent Isotropic Response as a Surrogate for Incident Field Strength

July 9, 2017
Author(s)
Dan Kuester, Duncan McGillivray, William F. Young, John M. Ladbury, Ari Feldman, Adam Wunderlich, Sheryl M. Genco
The strength of a radiated field at some location in free space can be described in terms of the equivalent conducted output from an isotropic probe antenna with a specified reference polarization. This metric has already entered use by various standards

A Radio Frequency Radiation Reverberation Chamber Exposure System for Rodents

March 17, 2017
Author(s)
Perry F. Wilson, John M. Ladbury, Galen H. Koepke, Capstick Myles, Niels Kuster, Sven Kuhn, Veronica Berdinas-Torres, Yijian Gong, David McCormick, James Gauger, Ronald Melnick
In this paper we present the novel design features, their technical implementation, and an evaluation of the radio frequency (RF) exposure systems developed for the National Toxicology Program (NTP) of the National Institute of Environmental Health

Life Time Dosimetric Assessment for Mice and Rats Exposed to Cell Phone Radiation in Reverberation Chambers

March 17, 2017
Author(s)
Perry F. Wilson, John M. Ladbury, Galen H. Koepke, Yijian Gong, Myles Capstick, Keven Kuhn, David L. McCormick, Ronald L. Melnick, Niels Kuster
In this paper, we present a detailed life time dosimetry analysis for individually housed rodents exposed to radio frequency (RF) signals. The unrestrained rodents were exposed in reverberation chambers for 2 years at three whole-body averaged specific

LTE impacts on GPS

February 15, 2017
Author(s)
William F. Young, Ari D. Feldman, Sheryl M. Genco, Azizollah Kord, Daniel G. Kuester, John M. Ladbury, Duncan A. McGillivray, Audrey K. Puls, Andre R. Rosete, Adam J. Wunderlich, Wen-Bin Yang
This report describes the test methodology from “LTE impacts on GPS: Test and Metrology Plan” developed by National Advanced Spectrum and Communications Test Network (NASCTN), and data that are the result of executing the test method. The fundamental goals

Interference and Coexistence of Wireless Systems in Critical Infrastructure

July 7, 2015
Author(s)
Galen H. Koepke, William F. Young, John M. Ladbury, Jason B. Coder
We examine interference and coexistence testing issues, test methods, and the need to update and develop new test methodologies related to the use of wireless devices in critical infrastructure systems. A case study on interference is presented along with

Measuring a Device's Susceptibility to LTE: Preliminary Approaches

March 15, 2015
Author(s)
Jason B. Coder, John M. Ladbury
Previous testing has shown that measuring a device’s susceptibility to a radiated, broadband signal can present a different set of challenges than those faced when testing with a narrow-band signal. Decisions ranging from choosing a measurement facility to

Proximity-effect test for lossy wireless-device measurements in reverberation chambers

January 4, 2015
Author(s)
Catherine A. Remley, Joop Aan Den Toorn, Christopher L. Holloway, John M. Ladbury, Chih-Ming Wang
We present a test method for quantifying and reducing systematic errors arising from antenna proximity to lossy objects in over-the-air performance testing of lossy large-form-factor wireless devices. The method determines the extent to which antenna

Absorption Characteristics and SAR of a Lossy Sphere inside a Reverberation Chamber

September 1, 2014
Author(s)
Christopher L. Holloway, Damir Senic, John M. Ladbury, Galen H. Koepke
This study presents an experimental approach to the analysis of absorption characteristics of a lossy dielectric object in a reverberant environment. The study used a canonically shaped water-filled sphere, convenient for ACS calculations (analytical or by

Characterizing a Device's susceptibility to broadband signals: A case study

August 4, 2014
Author(s)
Jason B. Coder, John M. Ladbury, David Hunter
It is common for electronic devices to be tested for their susceptibility to radiated signals they may be exposed to during their normal operation. A reverberation chamber is well suited to perform this type of testing because it can expose the device

Radiowave Propagation in Urban Environments with Application to Public-Safety Communications

August 4, 2014
Author(s)
William F. Young, Catherine A. Remley, Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, John M. Ladbury, Colton R. Dunlap
We characterize key elements that pose challenges to public-safety radio communications into and out of large buildings, including the strong attenuation of radio signals caused by losses and scattering in the building materials and structure, and the

A Two-Port Model for Antennas in an Arbitrary Environment

May 1, 2014
Author(s)
Jason B. Coder, John M. Ladbury, Mark Golkowski
We present an improved model for characterizing fundamental antenna parameters based on the concept of a passive realizable two-port network. The proposed model is consistent with circuit theory based approaches and allows for quantitative description and

On the Link Between Insertion Loss and Lower Bound of Efficiency

August 9, 2013
Author(s)
Levon Barsikyan, Jason Coder, Mark Golkowski, John M. Ladbury
We investigate the effect of chamber loss on the recently developed 2-port antenna model and the associated method of determining antenna efficiency. The loss in the reverberation chamber was controlled using microwave absorbing foam creating four

Characterizing Large-Form-Factor Devices in a Reverberation Chamber

July 15, 2013
Author(s)
Catherine A. Remley, Gerrit S. van de Beek, Christopher L. Holloway, John M. Ladbury
Abstract—With new technologies such as machine-to-machine communications there is a growing need to test large-formfactor devices in reverberation chambers. The performance of the reverberation chamber can be degraded by the physical characteristics of

Early-time Behavior in Reverberation Chambers and Its Effect on the Relationships Between Coherence Bandwidth, Chamber Decay Time, RMS Delay Spread, and the Chamber Build-up Time

August 12, 2012
Author(s)
Christopher L. Holloway, Haider Shah, Ryan J. Pirkl, Catherine A. Remley, David A. Hill, John M. Ladbury
The use of reverberation chambers for electromagnetic testing is widely being accepted for use in many measurement applications. In recent years reverberation chambers are beginning to merge as a test facility for testing wireless device and for emulating