Abstract/Details

Modeling electromagnetic wave propagation in electrically large structures


2002 2002

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Abstract (summary)

Existing unified numerical electromagnetic methods are often unable to analyze electrically large structures due to the amount of memory and processing power required, necessitating approximate analyses with limited applicability. In this research a hybrid modeling methodology is adopted to solve these complex problems more efficiently than unified numerical methods and more accurately than analytical methods. Electromagnetic modeling problems are divided into two or more levels of scale. Each level analyzes a specific level of detail and only promotes the required information to the next level. The method is demonstrated by successful application to three important problems: (1) remote sensing of snow, (2) modeling an optical Bragg resonator, and (3) modeling the MIMO wireless channel. First, complex snow media is analyzed with a hybrid FDTD/radiative transfer model. FDTD is used to compute phase matrices and extinction coefficients required for radiative transfer. Comparison with exact analytical methods proves the validity of the FDTD method for modest domain sizes ([5λ]3) and number of Monte Carlo realizations (32). The method is used to illustrate a penetrating sphere model, which is not possible with existing analysis techniques. Backscatter from the resulting model is about 3 times higher than that of existing dense-medium theories, underlying the importance of exact characterization of the media. Second, a, hybrid FD/FDTD/S-parameter analysis is developed to model a large (104 section) optical Bragg resonator: a simple FD method computes propagation constants and field profiles, FDTD analysis provides reflection and transmission coefficients for the single section, and S-parameter analysis combines the sections to obtain the complete device response. A detailed study on error suggests that the method provides better than 2% accuracy in reflection and transmission response. Third, a hybrid electromagnetic/SVA model is developed to study the indoor MIMO wireless channel. A MIMO measurement platform is discussed for simultaneous probing of up to 16 transmit and receive antennas, which was required to assess the validity of later modeling. FDTD or MOM antenna analysis coupled with the SVA model gives capacity predictions which match measured data. The model is used to explore the impact of antenna spacing, directivity, and polarization on channel capacity. Closely spaced antennas lead to an approximate halving of receive power. Directivity effectively doubles receive power for aligned transmit and receive. Dual polarization increases system capacity anywhere from 10% to 70%, depending on the spacing of elements and the amount of multipath richness. This analysis of MIMO systems underlines the need for models that describe both multipath richness and average receive power.

Indexing (details)


Subject
Electrical engineering;
Optics;
Remote sensing
Classification
0544: Electrical engineering
0752: Optics
0799: Remote sensing
Identifier / keyword
Applied sciences, Pure sciences, Electrically large structures, Electromagnetic wave, Wave propagation, Wireless channels
Title
Modeling electromagnetic wave propagation in electrically large structures
Author
Wallace, Jon William
Number of pages
327
Publication year
2002
Degree date
2002
School code
0022
Source
DAI-B 62/11, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
0493456244, 9780493456249
Advisor
Jensen, Michael A.
University/institution
Brigham Young University
University location
United States -- Utah
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3032995
ProQuest document ID
275884265
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/275884265
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