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Search Publications by: John Ladbury (Fed)

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Displaying 26 - 50 of 77

On Lower Bound Antenna Efficiency Measurements in a Reverberation Chamber

August 6, 2012
Author(s)
Jason B. Coder, John M. Ladbury
This paper addresses a few specific aspects of measuring the lower bound of antenna efficiency in a reverberation chamber. While the initial method for measuring the lower bound of efficiency has been presented, three key revisions are discussed here: (1)

A Novel Method for Determining the Lower Bound of Antenna Efficiency

December 31, 2011
Author(s)
Jason B. Coder, John M. Ladbury, Mark Golkowski
Determining the absolute antenna efficiency has been a difficult task since the inception of the antenna itself. While there are methods that can measure an antenna’s efficiency, most are complicated and prone to high uncertainties. A new method is

Measurement of Shielding Effectiveness of Electrically-Small Enclosures

August 13, 2011
Author(s)
Christopher L. Holloway, Colton R. Dunlap, John M. Ladbury, Joshua A. Gordon, Jason B. Coder, Galen H. Koepke
In the following we propose a technique for determining the shielding effectiveness (SE) an electrically small enclosure. In particular, we use this technique to explore the shielding characteristics of a rectangular box used to shield a satellite based

An Electromagnetic Evaluation of the NASA Space Power Facility at Plum Brook Station

July 1, 2011
Author(s)
Galen H. Koepke, John M. Ladbury, Dennis G. Camell, Jason B. Coder, Chriss A. Grosvenor, Randy Direen, Jeffrey R. Guerrieri
We describe in this report (Technical Note) an extensive electromagnetic evaluation of a unique test facility designed and built by the National Aeronautics and Space Administration (NASA). The Space Power Facility is presumed to be the world’s largest

Radio Frequency Measurements to Support Public Safety Wireless Communications in Large Buildings and Structures

June 13, 2011
Author(s)
William F. Young, Catherine A. Remley, Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, John M. Ladbury
The public safety community requires dependable wireless communications in buildings that often disrupt the radio frequency propagation due to the construction material, architectural features, or large physical dimensions. Here we introduce measurements

Examining the True Effectiveness of Loading a Reverberation Chamber

July 29, 2010
Author(s)
Jason Coder, John M. Ladbury, Christopher L. Holloway, Kate Remley
In this paper we explore how placing the same amount of absorber in different locations within a reverberation chamber can have different loading effects. This difference can have a significant impact on measurement reproducibility, both for measurements

Parametric Study on the use of Reverberation Chambers for Repeatable/Controllable Wireless Testing: Application to BER Measurements

April 12, 2010
Author(s)
Christopher L. Holloway, E Genender, Catherine A. Remley, John M. Ladbury, Galen H. Koepke
We illustrate use of the reverberation chamber to simulate different wireless propagation environments including effects such as narrowband or frequency-selective fading and Doppler spread. These effects have a strong impact on the quality of the wireless

Radio Wave Propagation Into Large Building Structures, Part 2: Characterization of Multipath

April 2, 2010
Author(s)
Catherine A. Remley, Galen H. Koepke, Christopher L. Holloway, Chriss A. Grosvenor, Dennis G. Camell, John M. Ladbury, Robert T. Johnk, William F. Young
We report on measurements that characterize multipath conditions that affect broadband wireless communications in building penetration scenarios. Measurements carried out in various large structures quantify both radio-signal attenuation and frequency

Measurements to Support Public Safety Communications: Attenuation and Variability of 750 MHz Radio Wave Signals in Four Large Building Structures: NIST Technical Note 1552

August 7, 2009
Author(s)
William F. Young, Kate Remley, John M. Ladbury, Christopher L. Holloway, Chriss A. Grosvenor, Galen H. Koepke, Sander Floris, Wouter Numan, Andrea Garuti
In this report, we investigate radio communication problems faced by emergency responders (firefighters, police, and emergency medical personnel) in disaster situations. A fundamental challenge to radio communications into and out of large buildings is the

Measurements of Metamaterial-Inspired, Electrically Small Antenna Systems

March 2, 2009
Author(s)
Christopher L. Holloway, John M. Ladbury, Richard Ziolkowski, Peng Jin, Chia-Ching Lin
The paper discusses the analysis and measurements of electrical small antennas. The antennas discussed here are based on antenna designed from metamaterial inspired concepts. An electromagnetic reverberation chamber is used for the test of the antennas. A

Using Reverberation Chambers to Determine the Shielding Effectiveness of Physically Small, Electrically Large Enclosures/Cavities

November 20, 2008
Author(s)
Christopher L. Holloway, David A. Hill, Marco Sandroni, John M. Ladbury, Jason B. Coder, Galen H. Koepke, Andrew C. Marvin
With the proliferation of small electric devices in recent years, along with various other applications, there is a growing need to test and determine the shielding properties or shielding effectiveness (SE) of physically small (but electrically large)

Source Stirring Technique for Reverberation Chambers; Experimental Investigation

September 8, 2008
Author(s)
Galen H. Koepke, Christopher L. Holloway, John M. Ladbury, David A. Hill, Valter Primiani, Paola Russo, Carlo Monteverde
The paper shows the source stirring technique from an experimental point of view. This technique exhibits good statistics for S21. The results illustrate that the field in the cavity has very similar characteristics to the field in a reverberation chamber

Use of Reverberation Chamber to Simulate the Power Delay Profile of a Wireless Environment

September 8, 2008
Author(s)
Christopher L. Holloway, E Genender, Catherine A. Remley, John M. Ladbury, Galen H. Koepke, H Garbe
Multipath propagation environment effects, such as frequency-selective fading, have a strong impact on the quality of the wireless channel. For example, multipath can impact bit error rate (BER) differently than Gaussian noise. For testing wireless devices

NIST Tests of the Wireless Environment in Automobile Manufacturing Facilities

September 1, 2008
Author(s)
Catherine A. Remley, Galen H. Koepke, Chriss A. Grosvenor, John M. Ladbury, Dennis G. Camell, Jason B. Coder, Robert Johnk
This report describes tests carried out by members of the NIST Electromagnetics Division to study the wireless environment in automotive manufacturing facilities. Testing was performed at three facilities during 2006 and 2007. We studied an assembly plant

Measurements to Support Modulated-Signal Radio Transmissions for the Public-Safety Sector

April 1, 2008
Author(s)
Catherine A. Remley, Galen H. Koepke, Christopher L. Holloway, Chriss A. Grosvenor, Dennis G. Camell, John M. Ladbury, Robert Johnk, David R. Novotny, William F. Young, George Hough, Michael McKinley, Yann Becquet, John Korsnes
We report on measurements of parameters utilized for characterization of broadband wireless technologies proposed for use by emergency responders (firefighters, police, and emergency medical personnel) and other public-safety personnel. We designed a

On the Use of Reverberation Chambers to Simulate a Controllable Rician Radio Environment for the Testing of Wireless Devices.

November 1, 2006
Author(s)
Christopher L. Holloway, David A. Hill, John M. Ladbury, Perry F. Wilson, Galen H. Koepke, Jason Coder
With the proliferation of wireless devices in recent years, there is a growing need to test the operation and functionality of these various devices in different multipath radio propagation environments, ranging from a direct line-of-sight environment to a

Requirements for an Effective Reverberation Chamber: Unloaded or Loaded

February 1, 2006
Author(s)
Christopher L. Holloway, David A. Hill, Galen H. Koepke, John M. Ladbury
In this paper we present two versions of a threshold metric for the purpose of accessing the effectiveness of a reverberation chamber. One metric is based on the chamber quality factor (Q), and the other is based on the volume of the loaded reverberation

Challenges in Using a Reverberation Chamber for Probe Calibration

February 13, 2005
Author(s)
John M. Ladbury, Dennis Lewis, Galen H. Koepke, Randy Direen
We discuss some of the challenges associated with attempts to calibrate electromagnetic field probes in a reverberation chamber. These include immunity issues, problems related to the transient nature of the fields in a reverberation chamber, and