NASA Scientific and Technical Aerospace Reports

Army, DARPA, MDA, Navy, NSA, and OSD-and also by the DOE, NASA, and NIST.
DTIC
Electro-Optics; Quantum Electronics; Solid State
20040111483 Army Research Lab., Adelphi, MD
Measured Characteristics of Selected S-Band Coaxial-to-Waveguide Adaptors
Coburn, William O.; Jul. 2004; 23 pp.; In English; Original contains color illustrations
Report No.(s): AD-A425440; ARL-TN-220; No Copyright; Avail: CASI; A03, Hardcopy
A design procedure for a leaky wave antenna fabricated in slitted waveguide was developed based on the analysis of
Goldstone and Oliner (1). The use of dielectric loading in slitted rectangular or dual-ridged waveguide is one way to influence
the antenna performance. An experimental fixture to evaluate the transmission line characteristics of miniaturized dual-ridged
waveguide was fabricated to allow for dielectric loading in the ridge section. The goal is to obtain experimental validation of
the theory as applied to a specific leaky dual-ridged waveguide loaded with conventional engineering plastics. As a first step
the effect of the coaxial-to-waveguide adaptors needed to feed and terminate the experimental fixture must be determined. The
offset short method is used to characterize commercial microwave adaptors requiring at least three different waveguide
lengths. Five different lengths of S-Band waveguide sections were available although some choices are more appropriate than
others depending on the frequency range of interest. The experimental results are used to calculate the scattering parameters
for five different microwave adaptors over the frequency range 2.8 to 3.2 GHz. The method and the limitations imposed by
not being able to use optimized waveguide lengths are described. A summary of the adaptor characteristics is provided for the
reference of other researchers so that the most appropriate part can be chosen for a given application.
DTIC
Adapters; Superhigh Frequencies; Ultrahigh Frequencies; Waveguides
20040111491 Industrial Coll. of the Armed Forces, Washington, DC
Electronics Industry Study Report: Semiconductors as Proxy
Bergin, William; Bryant, Leroy; Crticec, Emil; Galloway, Gary; Grandrath, William; Jan. 2002; 36 pp.; In English; Original
contains color illustrations
Report No.(s): AD-A425459; No Copyright; Avail: CASI; A03, Hardcopy
The U.S. Government in general and the Department of Defense in particular represent such a small portion of the
electronics industry’s business that without a significant change in policy and approach, equipment vital to our national
security may not be readily available. Using the semiconductor industry as a proxy for the sector, this study suggests ways
the U.S. can leverage the healthy (and bolster the flagging) portions of the commercial electronics sector to ensure ready access
to strategic items that will be required to provide the capabilities necessary to meet rapidly changing threats in a global
environment.
DTIC
Electronic Equipment; Industries; Security; Semiconductors (Materials)
20040111510 Woods Hole Oceanographic Inst., MA
Performance Analysis of Subaperture Processing Using a Large Aperture Planar Towed Array
Watson, Jennifer A.; Feb. 2004; 219 pp.; In English; Original contains color illustrations
Contract(s)/Grant(s): F19628-00-C-0002
Report No.(s): AD-A425488; MIT/WHOI-2004-02; No Copyright; Avail: CASI; A10, Hardcopy
In recent years the focus of passive detection and localization of submarines has moved from the deep ocean into the
littoral regions. The problem of passive detection in these regions is complicated by strong multipath propagation with high
transmission loss. Large aperture planar arrays have the potential to improve detection performance due to their high resolution
and high gain, but are susceptible to two main performance degradation mechanisms: limited spatial coherence of signals and
nonstationarity of high bearing rate interference sources common in littoral regions of strategic importance. This thesis
presents subarray processing as a method of improving passive detection performance using such large arrays. This thesis
develops statistical models for the detection performance of three adaptive, sample-covariance- based subarray processing
algorithms which incorporate the effects of limited spatial coherence as well as finite snapshot support. The performance of
the optimum processor conditioned on known data covariances is derived as well for comparison.
DTIC
Apertures; Planar Structures; Regions; Reliability Analysis; Sonar
101