in order to generate X-rays in the wavelength range required for fabrication of integrated circuits. The configuration consists of a quasi optical maser cavity through which a beam of relativistic electrons is made to propagate, spontaneously emitting X-rays of the desired energy. For 5 inch silicon wafers covered with a sensitive resist such as PBS, this translates into a throughput of 26 wafers/hr using an aggressive stepper. The scaling of X-ray power with wavelength indicates that the throughput can be increased substantially using resist which are sensitive to shorter wavelength X-rays. GRA (NASA-Case-NPO-17249-1-CU; US-Patent-4,819,064; A method and apparatus is developed for obtaining a stereo image with reduced depth distortion and optimum depth resolution. Static and dynamic depth distortion and depth resolution tradeoff is provided. Cameras obtaining the images for a stereo view are converged at a convergence point behind the object to be presented in the image, and the collection-surface-to-object distance, the camera separation distance, and the focal lengths of zoom lenses for the cameras are all increased. Doubling the distances cuts the static depth distortion in half while maintaining image size and depth resolution. Dynamic depth distortion is minimized by panning a stereo view-collecting camera system about a circle which passes through the convergence point and the camera's first nodal points. Horizontal field shifting of the television fields on a television monitor brings both the monitor and the stereo views within the viewer's limit of binocular fusion. Official Gazette of the U.S. Patent and Trademark Office N89-28677# Naval Research Lab., Washington, DC. RECIPROCAL PERFECT AND ASYMPTOTICALLY PERFECT PERIODIC RADAR WAVEFORMS AND THEIR APERIODIC PROPERTIES Karl Gerlach and Frank F. Kretschmer, Jr. 24 May 1989 23 p (AD-A208938; NRL-9059) Avail: NTIS HC A03/MF A01 CSCL 17/9 = Digitally coded radar waveforms can be employed to obtain large time-bandwidth products (pulse compression ratios). A perfect periodic code is defined to be a periodic code whose autocorrelation function has zero sidelobes and whose amplitude is uniform (maximum power efficiency 1). An asymptotically perfect periodic code has the property that as the number of elements in the code goes to infinity the code's autocorrelation function has zero sidelobes and its power efficiency is one. A new class of radar wave forms are introduced that are either perfect of asymptotically perfect codes. They are called reciprocal codes because they can be derived through a linear transformation of the known codes. The reciprocal code's aperiodic performance is examined. This is motivated by the tendency of good periodic codes to yield good aperiodic codes, and hence high pulse compression ratios with low sidelobe responses are attainable. GRA The problem of target detection and signal parameter estimation in a background of unknown interference is studied, using a multidimensional generalization of the signal models usually employed for radar, sonar, and similar applications. The required techniques of multivariate statistical analysis are developed and extensively used throughout the study, and the necessary mathematical background is provided in Appendices. Target detection performance is shown to be governed by a form of the Wilks' Lambda statistic, and a new method for its numerical evaluation is given which applies to the probability of false alarm of the detector. Signal parameter estimation is shown to be directly related to known techniques of adaptive nulling, and several new results relevant to adaptive nulling performance are obtained. N89-28679# OH. GRA Air Force Inst. of Tech., Wright-Patterson AFB, A METHODOLOGY FOR MODELING RADAR DETECTION (AD-A209153; AFIT/GST/ENS/89M-12) Avail: NTIS HC The purpose of this thesis is to develop a methodology for modeling fighter aircraft radar detection range performance. Response surface methodology is used to form a meta-model of the TAC BRAWLER Air Combat Model. Using experimental design theory, detection range data was collected using TAC BRAWLER and regressed to develop an equation for predicting radar detection range. The resulting equation is valid for specific ranges of the target's radar cross section, altitude, and airspeed and the attacker's altitude and airspeed. GRA Stephen C. Sanders May 1989 28 p (HDL Proj. E247E4) (AD-A209187; HDL-TM-89-5) Avail: NTIS HC A03/MF A01 CSCL 09/7 The Harry Diamond Lab. provided high-altitude electromagnetic pulse (HEMP) and partial lightning hardness verification testing to a high-frequency radio facility for the FAA. The facility consisted of a shielded enclosure with antennas and cables connected through protective devices at the shield to dummy loads within the shield. It was exposed to low-level radiation with measurements of internal fields extrapolated to threat levels and compared to specific criteria. Each typical penetration was injected with a simulated lightning source, and internal measurements were compared to specific criteria. Although criteria were not always met, it was judged with confidence that the facility would protect radio equipment. It was noted that the ac power spark gap would remain shorted until ac power shut down, resulting in system upset. GRA N89-28682# Air Force Inst. of Tech., Wright-Patterson AFB, EVALUATION OF THE BISTATIC EQUIVALENCE THEOREM (AD-A209228; AFIT/GE/ENG/89J-1) Avail: NTIS HC A08/MF A01 CSCL 17/9 This research examined the applicability of the monostaticbistatic equivalence theorem (MBET) and associated extensions in determining the extent to which correlation exists between monostatic and bistatic data for both the near and far-field. A secondary objective was to determine whether reliable bistatic near-field radar cross section (RCS) data could be collected on a range originally designed to take monostatic far-field measurements. Dr. David Falconer developed two extensions of the MBET in an effort to estimate the bistatic RCS pattern in both the near and far-field by measuring the monostatic RCS pattern at one-half the bistatic angle, at a reduced frequency, and, for the near-field case, at an adjusted target-to-receiver separation range. The pattern representation and accuracy of these two extensions were examined by measuring the RCS of an ogive, a circular flat plate, and two circular cylinders of different lengths. GRA N89-28683# Naval Postgraduate School, Monterey, CA. Dept. of Electrical and Computer Engineering. NEC (NUMERICAL ELECTROMAGNETICS CODE), NECGS (NUMERICAL ELECTROMAGNETICS CODE-GROUND SCREEN), AND MININEC (MINI-NUMERICAL ELECTROMAGNETICS CODE) NUMERICAL MODELS OF LF TOP-HAT MONOPOLE ANTENNAS M.S. Thesis Slamet Suharsa Padmosutoyo Mar. 1989 59 p (AD-A209230) Avail: NTIS HC A04/MF A01 CSCL 09/1 The U.S. Navy needs to increase the power handling capability of its current VLF and LF top-hat monopole antennas. This is most efficiently studied via numerical analysis of candidate antennas. Previous computer models based on the Numerical Electromagnetics Code (NEC-3) were shown to be unacceptable. The reasons for the inaccuracies were discovered to be NEC's inability to accurately model the effects of step changes of radius on adjacent portions of the structure. This thesis investigates two additional numerical models. The first uses the MININEC SYSTEM which has been shown to be accurate for stepped-radius antennas, and the second approximates a top-hat monopole antennas by a wire-cage structure. The latter employs NECGS, a special version of NEC-3 which efficiently uses radial symmetry. The performance parameters of interest which were calculated are static capacitance, resonant frequency, effective height, and radiation resistance. The results of these new models are compared to scale-model measurements and to the numerical results of the earlier NEC-3 study. The MININEC SYSTEM product acceptable values but is limited in the number of unknowns used to describe the model. NECGS results indicate that an acceptable wire-cage equivalency to a top-hat monopole may not exist. N89-28684*# GRA National Aeronautics and Space Administration. Pasadena Office, CA. DIGITAL CARRIER DEMODULATOR EMPLOYING COMPONENTS WORKING BEYOND NORMAL LIMITS Patent Application William J. Hurd, inventor (to NASA) and Ramin Sadr, inventor (to NASA) (Jet Propulsion Lab., California Inst. of Tech., Pasadena.) 12 May 1987 10 p (Contract NAS7-918) (NASA-Case-NPO-17628-1-CU; NAS 1.71:NPO-17628-1-CU; US-Patent-Appl-SN-350813) Avail: NTIS HC A02/MF A01 each at a frequency of F/2; passing one of the digital sample streams through the component designed to work at a frequency less than F where the component responds only to the odd or even digital samples in one of the digital sample streams; delaying the other digital sample streams for the time it takes the digital sample stream to pass through the component; and adding the one digital sample stream after passing through the component with the other delayed digital sample streams. In the specific example, the component is a finitie impulse response filter of the order ((N + 1)/2) and the delaying step comprised passing the other digital sample streams through a shift register for a time (in sampling periods) of ((N + 1)/2) + r, where r is a pipline delay through the finite impulse response filter. NASA N89-28685# Naval Postgraduate School, Monterey, CA. Thaddeus B. Welch, III Mar. 1989 150 p Integral equations (IE's) are widely utilized to calculate induced currents on antennas and scatters, but they are seriously restricted in their ability to handle inhomogeneous penetrable structures having multiwavelength dimensions. The utilization of finite element (FE) techniques has not been as pervasive as the use of IE's. The IE representation matrix is full, containing few, if any, zero valued elements. The techniques for operating on these large sized full matrices require undesirable amounts of processor time. FE techniques produce sparse matrices due to the strictly local interactions between discrete unknowns. The application of FE's to unbounded problems, however, requires supplementary enforcement of the far field radiation conditions. The Field Feedback Formulation (FFF) circumvents the full-matrix computational bottleneck by allowing FE based numerical methods to be employed. Even though the resultant spare matrices may be larger than the full matrices discussed earlier, most elements have a value of zero. Numerical procedures exist to optimize operations with these sparse matrices. Calculational speeds can be orders of magnitude faster. Computer technique to implement and validate this new technique are examined. Excellent agreement GRA with classical results are demonstrated. N89-28687# GRA Army Missile Command, Redstone Arsenal, AL. Directed Energy Directorate. DESIGN OF A COMMAND, COMMUNICATIONS, AND CONTROL VAN (SURROGATE) Final Technical Report, Jun.Nov. 1988 J. Darryl Holder and Jerome Fishback 24 Mar. 1989 28 p (AD-A207652; AD-E951351; AMSMI/TR-RD-DE-89-1) Avail: NTIS HC A03/MF A01 CSCL 25/5 This report describes the design, construction, and checkout of a radio and telephone multi-mode communications hub. This unit is to serve as a surrogate for a command, control, and communications van which is to be used in support of a special series of testing at a remote site. This unit is assembled in a military four-wheel van and has a crew of a commander and three operators. Radio communications monitoring can be performed all popular modes of transmission from 50 KHz to 2 GHz and transmission can be performed on selected frequencies in the in 40-meter, 6-meter, and 2-meter bands. Both voice and digital (teletype, packet, facsimile, etc.) communications are supported. GRA N89-28688# Army Construction Engineering Research Lab., Champaign, IL. THE RELATIONSHIP BETWEEN GROUND PERMITTIVITY AND THE INPUT IMPEDANCE OF A HORIZONTAL DIPOLE NEAR GROUND Final Report John H. Spears Apr. 1989 80 p (AD-A207746; CERL-TM-M-89/05) Avail: NTIS HC A05/MF A01 CSCL 20/14 Transmitting antennas located near the earth have a problem with electromagnetic scattering caused by the ground. Researchers suggest that the inverse of this problem may be used to determine the complex permittivity of the ground. That application is the goal of this thesis. The solution of the half-space problem was originally formulated in 1909 by Arnold Sommerfeld. Unfortunately, his formulation was written in terms of a set of integrals that tend to have a slow rate of convergence. Since then, researchers have sought faster methods of computing fields in the presence of an arbitrary infinite half space by making approximations to Sommerfeld's integrals to increase their convergence rate. Others have replaced the ground with an equivalent image current. N89-28690# Naval Ocean Systems Center, San Diego, CA. QUALITY FACTOR AND STATISTICS FOR RADIATION PATTERNS OF SHIPBOARD HF ANTENNAS Final Report, Feb. 1987 - Sep. 1988 E. A. Thowless and S. T. Li Sep. 1988 30 p (AD-A207931; NOSC/TD-1453) Avail: NTIS HC A03/MF A01 CSCL 20/14 The characteristics of various statistical entities of radiation patterns are reviewed in an effort to: improve the technical representation and definition of a figure-of-merit quality factor for antenna patterns; improve understanding of the distribution of pattern gain values; determine requirements for antenna patterns; improve understanding of the distribution of pattern gain values; determine requirements for antenna pattern statistical data for various applications; develop an improved antenna pattern statistical summary that employs the fewest numbers to provide a statistical characterization of radiation patterns. GRA A long-term Ecological Monitoring Program is being conducted to monitor for possible effects from the operation of the U.S. Navy's ELF Communications System to resident biota and their ecological relationships. Monitoring studies were selected through a peer reviewed, competitive bidding process in mid-1982, and work on most studies began in late summer of that year. Preliminary activities of the program consisted of site selection, characterization of critical study aspects, and validation of assumptions made in original proposals. Subsequently, increasing emphasis has been placed on the collection of preoperational and operational databases at the Michigan and Wisconsin Transmitting Facilities. The databases are being used to make proposed spatial and/or temporal comparisons of biological and ecological variables. This report summarizes the progress of the Ecological Monitoring Program during 1987. GRA N89-28692# National Telecommunications and Information METEOR BURST SYSTEM COMMUNICATIONS David Cohen, William Grant, and Francis Steele Mar. 1989 113 p (PB89-191167; NTIA-TR-89-241) Avail: NTIS HC A06/MF A01 CSCL 17B The technical and operating characteristics of meteor burst systems of importance for spectrum management applications are identified. A technical assessment is included which identifies the most appropriate frequency subbands within the VHF spectrum to support meteor burst systems. The electromagnetic compatibility of meteor burst systems with other equipments in the VHF spectrum is determined using computerized analysis methods for both ionospheric and ground wave propagation modes. It is shown that meteor burst equipments can cause and are susceptible to ground wave interference from other VHF equipments. Included are tables of geographical distance separations between meteor burst and other VHF equipments which satisfy interference threshold criteria. Author N89-28693# Nationaal Inst. voor Kernfysica en Hoge Energiefysica, Amsterdam (Netherlands). THE BEAM VIEWER [DE BEAMVIEWER] G. J. van Vliet and H. Nieuwenkamp 5 Oct. 1988 DUTCH (LINO-160; ETN-89-94920) Avail: NTIS HC A03/MF A01 13 p In The beam viewer and all the related apparatus such as camera, control, drive, illumination and wiring are considered. The beam viewer is an optical control system which checks position, form, and charge distribution, of the electron beam. It consists of a hard aluminum housing mounted in the beam line. In the housing there is a fluorescent plate (the TV target) which can be moved into the beam by a set of levers. When hit by electrons, the plate emits visible radiation which is detected by a camera. The degree of lightening of the plate is a measure of the beam charge density. ESA Nationaal Inst. N89-28694# voor Kernfysica en Hoge Energiefysica, Amsterdam (Netherlands). VIDEO PROCESSING USING THE MSX COMPUTER [VIDEOBEWERKING MET DE MSX-COMPUTER] G. J. van Vliet 18 Nov. 1988 17 p In DUTCH (LINO-163; ETN-89-94921) Avail: NTIS HC A03/MF A01 The processing of video images using the Philips MSX-2 computer is considered, with a view to the processing of video signals of beam viewers and the creation of an extra control function for the beam. The structure of the video signal is outlined. The control function is realized by the mixing of video signals with an ideal computer video plate. The MSX manual and the important commands are described. ESA N89-28695 British Aerospace Public Ltd. Co., Preston (England). ANTENNA FUNDAMENTALS: A TUTORIAL PAPER J. C. Robertson 7 Jan. 1988 44 P (BAe-WAA-R-GEN-RAD-533; TNAAS-439; ETN-89-95222) Avail: British Aerospace Public Ltd. Co., Preston Lancs PR4 1AX, United Kingdom The principles and characteristics of antennas, operating in the radio frequency band, are examined. A descriptive approach with the minimum of mathematical derivation is given. The antenna N89-28696 British Aerospace Public Ltd. Co., Preston (England). 50 p (BAE-WAA-RP-GEN-RAD-584; ETN-89-95223) Avail: British Aerospace Public Ltd. Co., Preston Lancs PR4 1AX, United Kingdom The basic principles of the airborne pulse Doppler radar are examined, to provide a foundation for the following studies on practical realizations of the pulse Doppler principle. The exploitation of the Doppler phenomenon offers the means, of discriminating among low level radar echoes from airborne targets and unwanted, strong swamping returns from such features (terrain background). It is demonstrated that the realization of the various types of practical pulse Doppler radars depends on parallel progress in the field of solid state, electronic, digital, signal processing hardware and on the development of processing algorithms. This dependency becomes vital with the demand for more versatility and multi-function capability from the compact, tactical pulse Doppler radar. It can be considered as a transducer/processor assembly to emphasize the equivalent status of the signal processing element vis a vis the front-end hardware. ESA N89-28697 British Aerospace Public Ltd. Co., Preston (England). AIRBORNE PULSE DOPPLER RADAR. PART 3: PERFORMANCE ESTIMATION J. C. Robertson 20 Apr. 1989 52 P (BAe-WAA-RP-GEN-RAD-645-Pt-3; TNAAS-445-Pt-3; ETN-89-95225) Avail: British Aerospace Public Ltd. Co., Preston Lancs PR4 1AX, United Kingdom Techniques and methods which can be used to obtain an indication of the performance capabilities of a pulse Doppler radar, of target fluctuation, clutter are analyzed. The effects characteristics, detailed radar parameters and radar-target encounter geometry, are discussed. The basic detection theory, the analysis of signal-to-noise ratio, the determination of the target detectability, the applications of the radar equation, and the operating limitations (other than thermal noise), are outlined. It is concluded that the prediction of radar maximum range performance can never be guaranteed to be accurate in the exact sense, and precise agreement between prediction and the results of limited ESA experimental measurement is not to be expected. N89-28698# Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt, Oberpfaffenhofen (West Germany). Abteilung HF-Systeme. POLARIMETRIC CALIBRATION USING PASSIVE CORNER Maurice Borgeaud Mar. 1989 29 p (DFVLR-FB-89-21; ISSN-0171-1342; ETN-89-95316) Avail: NTIS HC A03/MF A01; DFVLR, VB-PL-DO, Postfach 90 60 58, 5000 Cologne, Fed. Republic of Germany, 12.50 DM Polarization impurities, losses and gains in the receiver or transmitter of a radar system are taken into account using a polarimetric calibration procedure. Using only passive elements, the polarimetric calibration is carried out using one trihedral and two dihedral corner reflectors whose seams are rotated 45 degrees with respect to each other. Mathematically the procedure is equivalent to solving a nonlinear system of twelve equations with eleven unknowns. The detailed solution is presented and computer simulations are shown. 1989 166 p Sponsored by the Netherlands Foundation for Technical Sciences (ETN-89-95455) Avail: NTIS HC A08/MF A01 Johannes Wilhelmus T Eikenbroek Receivers in general, and the up conversion type in particular, are discussed. Noise optimization of the amplifier to the antenna is discussed. This optimization is a first requirement for maximum sensitivity of the receiver. A thorough analysis of the frequency dependent distortion performance of a differential pair used as either an automatic gain control stage or a switching mixer is presented. The design of surface acoustic wave resonators on ESA the piezoelectric substrate material quartz is discussed. N89-28700# Swedish Inst. of Space Physics, Uppsala. Bengt Lundborg et al 29 Mar. 1989 56 p Sponsored by the (IRF-SR-199; ISSN-0284-1703; ETN-89-95162) Avail: NTIS HC A04/MF A01 The single path propagation of pulses or wave packets through a smooth horizontally stratified ionospheric plasma is studied. The derivation of the ray tracing equations, are obtained and the usual expressions for the group path and pulse delay time is reviewed. The ionospheric transfer function involving the rise time is obtained. The rise time is shown to be larger for the high ray and for low frequencies on the low ray, and the most favorable communication over a few hundred kilometers is shown to be obtained with the low ray. Rise times are shown to be higher for profiles with scale lengths of an ordinary ionospheric layer, and typically in the range 1 to 10 microsecond; the lower value pertaining to a steeper ESA profile. N89-28701# Technische Univ., Delft (Netherlands). (ETN-89-95461) Avail: NTIS HC A08/MF A01 Techniques for carrying out the segmentation of images which are severely contaminated by noise are discussed. Attempts to improve performance by exploiting the spatial context and by incorporating generic a priori knoledge are described. Since accurate delineation of object regions is a priority, the research concentrates on edge-oriented methods. A sequential boundary detection method on the basis of dynamic programming is elucidated. The restricted-search dynamic programming boundary detection method is concluded to be a robust and useful tool, especially suited for application in image measurement systems. ESA N89-28702# Office National d'Etudes et de Recherches Aerospatiales, Paris (France). MULTITARGET TRACKING BY SINGLE SENSOR ANALYSIS OF THE MAIN APPROACHES DEVELOPED IN THIS AREA Jean Dezert 1988 159 p In FRENCH; ENGLISH summary as translation will also be announced Original report (ESA-TT-1171) (ONERA-NT-1988-10; ISSN-0078-3781; ETN-89-95292) Avail: NTIS HC A08/MF A01 The most important multitarget trackig methods using a single sensor system are analyzed, based on a bibliographical review. Two basic approaches are proposed: the Bayes decision rule approach, and the maximum likelihood approach. The methods using the Bayes decision rule approach are superseding those based on the maximum likelihood theory and special attention is therefore devoted to them in this analysis. N89-28703# ESA Office National d'Etudes et de Recherches Aerospatiales, Paris (France). A METHOD FOR ASSISTING IN DECISION-MAKING FOR MULTILAYER RADAR ABSORBENT COVERINGS Ph.D. Thesis ESA - Paris VI Univ. Annie Bastiere Original report In FRENCH; ENGLISH summary announced be as translation (ESA-TT-1173) (ONERA-NT-1989-2; ISSN-0078-3781; ETN-89-95294) Avail: NTIS HC A12/MF A01 A multicriteria optimization method for multi-layer radar absorbent coverings destined for use with existing aircraft is presented. This technique first uses an optimization procedure with nonlinear constraints, specifically the generalized projected gradient method. Next, the application of a modified multi-criteria decision theory fuses several design criteria and provides decision assistance to the designer. The method permits the use of three fusion laws, one based on the Dempster-Shafer theory of evidence, and two based on fuzzy set theory. Experimental results of the proposed method are presented. They concern materials of the same class configured with three layers, as well as materials of different classes configured with one to five layers. ESA N89-28882# Joint Publications Research Service, Arlington, VA. HIGHER ORDER BASE DYNAMICS OF A BIPOLAR The modeling of bipolar transistors is studied in the case when the quasi-static assumption does not hold, i.e., the base and collector currents follow the controlling voltages not at once, but with certain time delays. In the case of nonuniform base doping, the magnitudes of these delays are calculated by first solving numerically the minority carrier distribution in the base region. A simple but realistic model for the doping density is presented. A higher order carrier distribution is then found, enabling one to obtain the time delays. They are found to be slightly larger but in the same order of magnitude compared to the base transit time as in the case of constant base doping, although the transit time is greatly diminished due to the base doping gradient. Author N89-28705# Department of the Army, Washington, DC. OPTICAL GAIN CONTROL OF GaAs MICROWAVE MONOLITHIC INTEGRATED CIRCUIT DISTRIBUTED AMPLIFIER Patent Application 19 p Arthur Paolella, inventor (to Army) and Peter R. Herczfeld, inventor (to Army) 27 Feb. 1989 (AD-D013969; US-Patent-Appl-SN-316358) A03/MF A01 CSCL 09/5 Avail: NTIS HC An optical gain control circuit for controlling the gain of a GaAs MMIC distributed amplifier having a dc gain control is provided. Variable intensity light from a controlled LED is directed to the surface of a GaAs multi-finger FET by means of an optical fiber. The FET is gate biased to a point near pinch-off to maximize its light sensitivity and the drain and source of the FET are serially connected with a fixed resistance in a dc voltage divider circuit so that the output of the voltage divider circuit changes as a function of the change in light intensity of the LED. A MMIC operational amplifier connected in an inverter mode is coupled between the output of the voltage divider circuit and the dc gain control of the distributed amplifier to control the gain of that amplifier. GRA National Inst. of Standards and Technology, Center for Electronics and Electrical N89-28706# Gaithersburg, MD. Engineering. CENTER FOR ELECTRONICS AND ELECTRICAL The 18th issue is presented of a quarterly publication providing information on the technical work of the National Institute of Standards and Technology (formerly the National Bureau of Standards) Center for Electronics and Electrical Engineering. The issue of the Center for Electronics and Electrical Engineering Technical Publication Announcements covers the third quarter of calendar year 1988. Author N89-28707# National Inst. of Standards and Technology, Boulder, PERFORMANCE EVALUATION OF RADIOFREQUENCY, |