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Search Publications by: John Ladbury (Fed)

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Displaying 51 - 75 of 154

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