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Electrical and Computer Engineering

Brigham Young University

1997

Articles 1 - 6 of 6

Full-Text Articles in Engineering

Azimuthal Modulation Of C-Band Scatterometer Over Southern Ocean Sea Ice, David G. Long, David S. Early Sep 1997

Azimuthal Modulation Of C-Band Scatterometer Over Southern Ocean Sea Ice, David G. Long, David S. Early

Faculty Publications

In a continuing evaluation of the ERS-1 C-band scatterometer as a tool for studying polar sea ice, the authors evaluate the azimuthal modulation characteristics of Antarctic sea ice. ERS-1 AMI scatterometer mode data sets from several study regions dispersed in the Antarctic seasonal sea ice pack are evaluated for azimuthal modulation. When appropriate, the incidence angle dependence is estimated and removed in a study region before determining whether azimuthal modulation is present in the data. Other comparisons are made using the fore and aft beam measurement difference. The results show that over the ice pack, azimuthal modulation is less than …

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A Unified Green's Function Analysis Of Complicated Dfb Lasers, Jim D. Freeze, Michael A. Jensen, Richard H. Selfridge Aug 1997

A Unified Green's Function Analysis Of Complicated Dfb Lasers, Jim D. Freeze, Michael A. Jensen, Richard H. Selfridge

Faculty Publications

An efficient full-wave analysis technique for one-dimensional optical domains, known as the recursive Green's function method (RGFM), is presented for evaluation of distributed feedback (DFB) laser cavities with arbitrary material profiles. The method first constructs the Green's function of an inhomogeneous domain and subsequently uses Green's theorem to determine the laser optical field, lasing wavelength, and threshold gain. The technique is applied to investigate the performance of three DFB laser structures: a chirped-grating configuration, a modulated stripe width design, and a reduced duty cycle complex-coupled device. These structures are evaluated in terms of their single-mode lasing behavior and the uniformity …

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Secondary Dark Rings Of Internal Conical Refraction, Karl F. Warnick, David V. Arnold May 1997

Secondary Dark Rings Of Internal Conical Refraction, Karl F. Warnick, David V. Arnold

Faculty Publications

This paper treats the phenomenon of internal conical refraction, in which a narrow beam propagating along an optical axis of a biaxial anisotropic medium spreads into a hollow cone. An expression is obtained for the intensity distribution produced by conical refraction that predicts additional fringes concentric to the well known Poggendorf dark ring for certain propagation distances and beam widths.

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Teaching Electromagnetic Field Theory Using Differential Forms, Karl F. Warnick, Richard H. Selfridge, David V. Arnold Feb 1997

Teaching Electromagnetic Field Theory Using Differential Forms, Karl F. Warnick, Richard H. Selfridge, David V. Arnold

Faculty Publications

The calculus of differential forms has significant advantages over traditional methods as a tool for teaching electromagnetic (EM) field theory. First, films clarify the relationship between field intensity and flux density, by providing distinct mathematical and graphical representations for the two types of fields. Second, Ampere's and Faraday's laws obtain graphical representations that are as intuitive as the representation of Gauss's law. Third, the vector Stokes theorem and the divergence theorem become special cases of a single relationship that is easier for the student to remember, apply, and visualize than their vector formulations. Fourth, computational simplifications result from the use …

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Tradeoffs In The Design Of A Spaceborne Scanning Pencil Beam Scatterometer: Application To Seawinds, David G. Long, Chialin T. Wu, Michael W. Spencer Jan 1997

Tradeoffs In The Design Of A Spaceborne Scanning Pencil Beam Scatterometer: Application To Seawinds, David G. Long, Chialin T. Wu, Michael W. Spencer

Faculty Publications

SeaWinds is a spaceborne wind scatterometer to be flown on the second Japanese Advanced Earth Observing Satellite (ADEOS-II) in 1999. An important international element of NASA's Earth Observing System (EOS), SeaWinds is an advanced follow-on to the NASA scatterometer (NSCAT) on the first ADEOS platform. Unlike previous operational spaceborne scatterometer systems. SeaWinds employs a scanning "pencil-beam" antenna rather than a "fan-beam" antenna, making the instrument more compact and yielding greater ocean coverage. The goals of this paper are twofold. First, the overall SeaWinds functional design and backscatter measurement approach are described, and the relative advantages of the pencil-beam technique are …

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Radar Backscatter Measurement Accuracy For A Spaceborne Pencil-Beam Wind Scatterometer With Transmit Modulation, David G. Long, Michael W. Spencer Jan 1997

Radar Backscatter Measurement Accuracy For A Spaceborne Pencil-Beam Wind Scatterometer With Transmit Modulation, David G. Long, Michael W. Spencer

Faculty Publications

Scatterometers are remote sensing radars designed to measure near-surface winds over the ocean. The difficulties of accommodating traditional fan-beam scatterometers on spacecraft has lead to the development of a scanning pencil-beam instrument known as SeaWinds. SeaWinds will be part of the Japanese Advanced Earth Observing Satellite II (ADEOS-II) to be launched in 1999. To analyze the performance of the SeaWinds design, a new expression for the measurement accuracy of a pencil-beam system is required. In this paper the authors derive a general expression for the backscatter measurement accuracy for a pencil-beam scatterometer which includes the effects of transmit signal modulation …

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