Theory and Applications of Aperiodic (Random) Phased Arrays

A need for network centric topologies using mobile wireless communications makes it important to investigate new distributed beamforming techniques. Platforms such as micro air vehicles (MAVs), unattended ground sensors (UGSs), and unpiloted aerial vehicles (UAVs) can all benefit from advances in this area utilizing advantages in stealth, enhanced survivability and maximum maneuverability. Moreover, in this dissertation, electromagnetic radiation is investigated such that the signal power of each element is coherently added in the far-field region of a specified target direction with net destructive interference occurring in all other regions to suppress sidelobe behavior. This provides superior range and resolution characteristics for a variety of applications including; early warning radar, ballistic missile defense and search and rescue efforts. A wide variety of topologies can be used to confine geometrically these mobile random arrays for analysis. The distribution function for these topologies must be able to generalize the randomness within the geometry. By this means it is feasible to assume the random element distribution of a very large volumetric space will yield either a normal or Gaussian distribution. Therefore the underlying assumption stands that the statistically averaged beam pattern develops from an arrangement of uniformly or Gaussian distrusted elements; both confined to a variety of geometry of radius A and is further generalized using a simple theory based upon the Fourier Transform. Hence, this theory will be derived and serve as the foundation for advanced performance characteristics of these arrays such as its ability for sidelobe tapering, adaptive nulling and multi beam control. In addition it will be shown that for the most ideal of conditions a steerable beam pattern free of sidelobe behavior (better known as a Gaussian distribution) is quite possible. As well these random array structures will be shown to provide superior bandwidth capability over tradiational array structures since they are frequency independent. Last of all a summary of the random array analysis and its results concludes this dissertation

A w-band quasi-optical mode converter and gyro-BWO experiment

High power coherent microwave sources at shorter wavelengths (mm and sub-mm) are in great demand, especially in the fields of plasma physics, remote sensing and imaging and for electron spin resonance spectroscopy. Gyro-devices are by their nature particularly suited to this type of application due to the fast-wave cyclotron resonance maser instability, which is capable of producing high power radiation at frequencies that prove challenging for other sources. A W-band gyro-device based on a cusp electron beam source with a helically corrugated interaction region is currently under development to provide a continuously tuneable source over the range between 90 GHz to 100 GHz with a CW power output of ~10 kW. The work presented herein encompasses the design, construction and measurement of a prototype output launcher for this gyro-device. A corrugated mode converting horn was designed to act as a quasi-optical mode converter that converts the fundamental operating mode within the gyro-TWA (TE11) to a hybrid mode, which is closely coupled to the fundamental free space Gaussian mode (TEM00). This free space mode allows the possibility for the inclusion of an energy recovery system that can recover a percentage of the energy from the spent electron beam and is predicted to increase overall efficiency by up to 40%. For this scheme the electron beam must be decoupled from the radiation, which can pass through the collector system and vacuum window unperturbed while the electrons are collected at the energy recovery system. This type of corrugated mode converting horn was chosen due to the advantages of a greater bandwidth and the capability to provide a source that is continuously tuneable over this bandwidth. The results of the design and integration of this corrugated mode converting horn with the gyro-device are presented. The prototype operates over a continuously tuneable bandwidth of 90 to 100 GHz with a return loss better than -35 dB and a Gaussian coupling efficiency of 97.8%. The far field radiation pattern shows a highly symmetrical structure with 99.9% of the power radiated within a cone with a half angle of less than 19° and a cross-polar level less than -40 dB.High power coherent microwave sources at shorter wavelengths (mm and sub-mm) are in great demand, especially in the fields of plasma physics, remote sensing and imaging and for electron spin resonance spectroscopy. Gyro-devices are by their nature particularly suited to this type of application due to the fast-wave cyclotron resonance maser instability, which is capable of producing high power radiation at frequencies that prove challenging for other sources. A W-band gyro-device based on a cusp electron beam source with a helically corrugated interaction region is currently under development to provide a continuously tuneable source over the range between 90 GHz to 100 GHz with a CW power output of ~10 kW. The work presented herein encompasses the design, construction and measurement of a prototype output launcher for this gyro-device. A corrugated mode converting horn was designed to act as a quasi-optical mode converter that converts the fundamental operating mode within the gyro-TWA (TE11) to a hybrid mode, which is closely coupled to the fundamental free space Gaussian mode (TEM00). This free space mode allows the possibility for the inclusion of an energy recovery system that can recover a percentage of the energy from the spent electron beam and is predicted to increase overall efficiency by up to 40%. For this scheme the electron beam must be decoupled from the radiation, which can pass through the collector system and vacuum window unperturbed while the electrons are collected at the energy recovery system. This type of corrugated mode converting horn was chosen due to the advantages of a greater bandwidth and the capability to provide a source that is continuously tuneable over this bandwidth. The results of the design and integration of this corrugated mode converting horn with the gyro-device are presented. The prototype operates over a continuously tuneable bandwidth of 90 to 100 GHz with a return loss better than -35 dB and a Gaussian coupling efficiency of 97.8%. The far field radiation pattern shows a highly symmetrical structure with 99.9% of the power radiated within a cone with a half angle of less than 19° and a cross-polar level less than -40 dB

The Deep Space Network

Work accomplished on the Deep Space Network (DSN) was described, including the following topics: supporting research and technology, advanced development and engineering, system implementation, and DSN operations pertaining to mission-independent or multiple-mission development as well as to support of flight projects

Publications of the Jet Propulsion Laboratory, July 1969 - June 1970

JPL bibliography of technical reports released from July 1969 through June 197

Space programs summary no. 37-62, volume 3 for the period 1 February - 31 March 1970. Supporting research and advanced development

Spacecraft communication, equipment, guidance, construction materials, propulsion, and related researc

ACCURACY OF GAUSS-LAGUERRE POLAR MONOPULSE RECEIVER

In this paper the CRB accuracy of a monopulse receiver parametrized by two (off-boresight and revolution) angles obtained by combining polar-separable and angularly periodic Gauss-Laguerre directivity patterns is calculated and compared to the CRB of monopulse receivers based on cartesian separable beams

Defense Technical Information Center thesaurus

This DTIC Thesaurus provides a basic multidisciplinary subject term vocabulary used by DTIC to index and retrieve scientific and technical information from its various data bases and to aid DTIC`s users in their information storage and retrieval operations. It includes an alphabetical posting term display, a hierarchy display, and a Keywork Out of Context (KWOC) display

Six Decades of Flight Research: An Annotated Bibliography of Technical Publications of NASA Dryden Flight Research Center, 1946-2006

Titles, authors, report numbers, and abstracts are given for nearly 2900 unclassified and unrestricted technical reports and papers published from September 1946 to December 2006 by the NASA Dryden Flight Research Center and its predecessor organizations. These technical reports and papers describe and give the results of 60 years of flight research performed by the NACA and NASA, from the X-1 and other early X-airplanes, to the X-15, Space Shuttle, X-29 Forward Swept Wing, X-31, and X-43 aircraft. Some of the other research airplanes tested were the D-558, phase 1 and 2; M-2, HL-10 and X-24 lifting bodies; Digital Fly-By-Wire and Supercritical Wing F-8; XB-70; YF-12; AFTI F-111 TACT and MAW; F-15 HiDEC; F-18 High Alpha Research Vehicle, F-18 Systems Research Aircraft and the NASA Landing Systems Research aircraft. The citations of reports and papers are listed in chronological order, with author and aircraft indices. In addition, in the appendices, citations of 270 contractor reports, more than 200 UCLA Flight System Research Center reports, nearly 200 Tech Briefs, 30 Dryden Historical Publications, and over 30 videotapes are included