Publications

Displaying 151 - 175 of 431

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

Measurement of the Stochastic Electromagnetic Field Coupling to an Unshielded Twisted Pair Cable

September 1, 2014

Author(s)

Christopher L. Holloway, John M. Ladbury

Abstract-Measurements of the field-to-wire coupling to an unshielded twisted pair of wires have been carried out in a reverberation chamber. The wires were twisted as a helix around a dielectric support and placed inside the chamber's working volume. The

Broadband Rydberg Atom Based Self-Calibrating RF E-field Probe

August 16, 2014

Author(s)

Christopher L. Holloway, Joshua A. Gordon, Steven R. Jefferts, Thomas P. Heavner

We present a significantly new approach for an electric (E) field probe. The probe is based on the interaction of RF-fields with Rydberg atoms, where alkali atoms are excited optically to Rydberg states and the applied RF-field alters the resonant state of

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

Introduction to Three Papers on Radio-Propagation Studies Related to Public-Safety Communications

July 30, 2014

Author(s)

Christopher L. Holloway

The National Institute of Standards and Technology (NIST) is involved in a several year effort to understand and address the communication problems that first responders (e.g., firefighters, police, and EMS) are confronted with day-to-day and in large

Millimeter Wave Detection via Autler-Townes Splitting in Rubidium Rydberg Atoms

July 17, 2014

Author(s)

Joshua A. Gordon, Christopher L. Holloway, Andrew Schwarzkopf, Dave Anderson, Stephanie Miller, Nithiwadee Thaicharoen, Georg Raithel

In this paper we demonstrate the detection of millimeter waves via Autler-Townes splitting in 85Rb Rydberg atoms. This method may provide an independent atomic-based SI-traceable method for measuring mm-wave electric fi elds, which addresses a gap in

Sub-wavelength imaging and field mapping via electromagnetically induced transparency and Autler-Townes splitting in Rydberg atoms

June 16, 2014

Author(s)

Christopher L. Holloway, Joshua A. Gordon

Using a quantum-optics technique known as Electromagnetically Induced Transparency (EIT) and Autler-Townes splitting, we present a technique for sub-wavelength imaging and field mapping of electrical fields ranging from 1~GHz to 500~GHz. The technique is

Propagation Measurements Before, During, and After the Collapse of Three Large Public Buildings

June 1, 2014

Author(s)

Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, William F. Young, Catherine A. Remley

NIST is investigating radio communications problems faced by emergency responders (e.g., firefighters and police) in disaster situation such as collapsed buildings. A fundamental challenge to communication into and out of large buildings is the strong

Path Loss and Large-Scale Site and Frequency Diversity in Urban Peer-to-Peer Channels for Six Public Safety Frequency Bands

April 1, 2014

Author(s)

David W. Matolak, Christopher L. Holloway, Kate Remley, Qian Zhang, Qiong Wu

We report on peer-to-peer (ground-based) large scale wireless channel characteristics for an urban environment in six public safety bands, for five simultaneous receiving sites. Results are based upon measurements taken in Denver in July 2009 with

Intra-volume, centralised array concept for improved public-safety communications

August 20, 2013

Author(s)

Christopher L. Holloway, William F. Young

Here we report on the testing and measurements of an intra-volume ad hoc array concept suitable for public-safety communications in buildings. The term ad hoc array refers to the use of several small communication devices that are randomly placed in an

Correlation Coefficient and Loading Effects for MIMO Antennas in a Reverberation Chamber

August 13, 2013

Author(s)

Nick Janssen, Kate Remley, Christopher L. Holloway, William F. Young

The correlation coefficient is a common metric for assessing the performance of an antenna for a multiple-input, multiple-out wireless device. In this paper, the effect of loading a reverberation chamber on the calculation of the correlation coefficient is

Influence on Q-Factor of Proximity and Orientation with Respect to Large-Form-Factor Loads in a Reverberation Chamber

August 13, 2013

Author(s)

Willem Burger, Christopher L. Holloway, Kate Remley

In this paper, it is shown that the presence of largeform-factor loads in close proximity to an antenna under test can affect the measured Q-factor (if measured improperly) in a reverberation chamber, possibly influencing the results of further

Proximity and Antenna Orientation Effects for Large-Form-Factor Devices in a Reverberation Chamber

August 8, 2013

Author(s)

Willem Burger, Kate Remley, Christopher L. Holloway, John M. Ladbury

Recent research has shown that large-form-factor devices can affect radiated power measurements in a reverberation chamber due to absorbtion and physical blocking by lossy material present in the device. In this paper, these effects are explained and

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