Showing papers by "Raytheon published in 1992"

Taguchi on Robust Technology Development: Bringing Quality Engineering Upstream

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Precipitation Estimation in Mountainous Terrain Using Multivariate Geostatistics. Part I: Structural Analysis

Abstract: Values of average annual precipitation (AAP) are desired for hydrologic studies within a watershed containing Yucca Mountain, Nevada, a potential site for a high-level nuclear-waste repository. Reliable values of AAP are not yet available for most areas within this watershed because of a sparsity of precipitation measurements and the need to obtain measurements over a sufficient length of time. To estimate AAP over the entire watershed, historical precipitation data and station elevations were obtained from a network of 62 stations in southern Nevada and southeastern California. Multivariate geostatistics (cokriging) was selected as an estimation method because of a significant (p = 0.05) correlation of r = .75 between the natural log of AAP and station elevation. A sample direct variogram for the transformed variable, TAAP = ln [(AAP) 1000], was fitted with an isotropic, spherical model defined by a small nugget value of 5000, a range of 190 000 ft, and a sill value equal to the sample variance ...

Beamed microwave power transmission and its application to space

Abstract: The general principles and special components of beamed microwave power transmission systems are outlined, and their application to the space program is discussed. For a beamed system starting with a DC source of power, converting it to a microwave beam for transmission through space, and ending with DC power output at the receiving end, an experimentally measured and certified DC-to-DC efficiency of 54% has been achieved. The application that is discussed in detail is a low-earth-orbit-to-geostationary-orbit (LEO to GEO) transportation system that depends on vehicles propelled by electric thrusters whose power is supplied by a microwave beam originating at the earth's surface. A scenario for such a system is chosen, and the performance results are presented. The advantages of the all electronic system over a chemically propelled system are enumerated. The principles of space propulsion, particularly as they relate to electric propulsion, are outlined. Key components at the terminals of the system are discussed. Environmental considerations are discussed. >

Precipitation Estimation in Mountainous Terrain Using Multivariate Geostatistics. Part II: Isohyetal Maps

Abstract: Values of average annual precipitation (AAP) may be important for hydrologic characterization of a potential high-level nuclear-waste repository site at Yucca Mountain, Nevada. Reliable measurements of AAP are sparse in the vicinity of Yucca Mountain, and estimates of AAP were needed for an isohyetal mapping over a 2600-square-mile watershed containing Yucca Mountain. Estimates were obtained with a multivariate geostatistical model developed using AAP and elevation data from a network of 42 precipitation stations in southern Nevada and southeastern California. An additional 1531 elevations were obtained to improve estimation accuracy. Isohyets representing estimates obtained using univariate geostatistics (kriging) defined a smooth and continuous surface. Isohyets representing estimates obtained using multivariate geostatistics (cokriging) defined an irregular surface that more accurately represented expected local orographic influences on AAP. Cokriging results included a maximum estimate within...

A general noise de-embedding procedure for packaged two-port linear active devices

Abstract: A method based on the noise correlation technique and its applications is described. The package, which need not be reciprocal, may consist of an arbitrary interconnection of linear passive elements at thermal equilibrium. Only the terminal admittance properties of the package need be known. However, in certain special cases which lead to singular submatrices of the admittance matrix, the method is inapplicable. This situation can occur when elements such as isolators are part of the package. The necessary theoretical foundation and experimental techniques to enable workers not familiar with the field to assemble the software and laboratory setup for two-port noise de-embedding is provided. The automated noise measurement system used for data acquisition and the mathematical basis for it are described in some detail. The validity of the de-embedding approach is established with extensive experimental data obtained on three MESFETs and a pseudomorphic HEMT. >

Autoregressive modeling of wide-band indoor radio propagation

Abstract: Based on frequency domain measurements in the 0.9-1.1-GHz band, an autoregressive model for the frequency response of the indoor radio channel is introduced. It is shown that a second-order process is sufficient to represent the important statistical characteristics of the channel both in the frequency domain and the time domain where each pole identifies the arrival of a cluster of paths. A comparison is made between the statistical characteristics of the empirical data and of the channel responses regenerated from the second-order AR processes. Four methods to regenerate the indoor radio channel responses from a second-order AR model are proposed. The accuracy of the methods is examined by comparing the cumulative distribution functions of the RMS delay spread and the 3-dB width of the frequency correlation function with that of the measurements performed in global, local, and mixed indoor radio propagation experiments. >

Stacked chip assembly and manufacturing method therefor

Abstract: Two or more integrated circuit or memory chips (64-66, 104, 106-108, 116-118, 122-126) are stacked on a circuit substrate (72, 100) or a printed-wiring board in such a manner that the planes of the chips lie horizontally, rather than vertically, on the substrate or wiring board. The chips are preferably interconnected along all of their edges (68) and thence, preferably by ribbon bonds, to the substrate or wiring board. The thus assembled arrangement is hermetically sealed by coatings of passivation and encapsulant. Such chips (25) are oversized, as distinguished from chips conventionally diced from wafers. Specifically, each chip is larger than an individual wafer circuit (18, 20), that is, each wafer portion (24) which is selected to be formed into a chip has a size that is larger than the individual wafer circuit which it incorporates, thus overlapping adjacent circuits.

Interference suppressor for a radio receiver

Abstract: The RF input of a radio receiver is converted to IF including received signal, noise and interference and fed to an interference detector and to an interference canceler of an interference suppressor. A fast Fourier transform (FFT) at the front end of the interference detector detects samples of all the interferences in the frequency domain. The frequency domain samples are scaled for gain control and detection of interferences above a predetermined threshold. The interference detector suppresses interferences to the predetermined threshold level. The scaled frequency domain interference samples are phase rotated and fed to an inverse fast Fourier transform to obtain a time domain replica of the interferences which are phase shifted replicas of the detected interferences. Such digital time domain replicas are converted to a continuous analog replica of the interferences, converted back to IF and summed with the original IF which included received signals, noise and interferences in order to cancel the interferences at the output of the interference suppressor.

High frequency resonant gate drive for a power MOSFET

Abstract: An efficient power MOSFET resonant gate drive circuit having a large coupled inductor between and in series with two switching transistors. The inductor prevents cross-conduction from the power bus through the drive transistors as may be caused by simultaneous turn-on due either to switching delays or single-event-upset-radiation from energetic cosmic rays. In either case, the inductor presents a high impedance for current that tries to flow through both transistors simultaneously. A center tap on the inductor is connected to the gate of the power MOSFET. An equivalent inductance resonates with the equivalent capacitance of the gate of the power MOSFET providing fast turn-on of the power MOSFET. During turn-off of the power MOSFET, one drive transistor is switched-off and the other drive transistor is switched-on. The voltage generated by the coupled inductor exceeds the magnitude of the input voltage causing a diode within the off-transistor to turn-on and return energy back to the power source, thereby further increasing the circuit efficiency.

Synthetic aperture radar guidance system and method of operating same

Abstract: A synthetic aperture radar guidance system adapted for use in a guided missile is described wherein the frequency of the transmitted pulses changes with time with a chirp slope which varies with range. The time between pulses also changes as a function of range. The desired values of the chirp slope and the interpulse interval are computed for all values within a range of interest and stored. Furthermore, the operating parameters of the SAR are changed as the range changes. The time intervals and frequencies are selected to avoid interruption ambiguities and eclipsing. The phase and frequency of the synthesized signal are controlled to adjust for motion of a vehicle on which the SAR is mounted. The SAR is operated in several modes. In a search mode, the beam of transmitted pulses is steered across a mapping area to form a plurality of patches of the mapping area. The patches are combined into one map of the entire area. Each pixel of the map is compared with a target template until a match is provided. Then the SAR operates in track mode wherein a correlation process ensures the missile is steered toward the target area using a template provided using known feature data.

Critical-point phonon frequencies of diamond.

Abstract: The phonon-dispersion curves derived from neutron-scattering experiments performed on diamond [J. Warren et al., Phys. Rev. 158, 805 (1967)] are not accurate enough to yield the exact frequencies of critical-point (CP) phonons and, thus, to provide a satisfactory interpretation of second-order optical spectra. A self-consistent analysis of such spectra [S. Solin and A. Ramdas, Phys. Rev. B 1, 1687 (1970)] was not fully successful because of ambiguities that arise in assigning second-order infrared absorptions and features in the Raman spectra to specific two-phonon summations. A more effective method for obtaining accurate CP phonon frequencies involves investigating defect-activated one-phonon absorptions; in this paper, we take advantage of the availability of chemically vapor-deposited (CVD) diamond for the purpose of locating and assigning infrared (ir) absorption features in the one-phonon region to CP phonons at the Brillouin-zone boundary. Fourier-transform ir absorbance spectra of CVD diamond exhibit a complex structure at wave numbers below the 1332.5-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ lattice-mode cutoff, which is induced by impurity-associated defect centers and yields the exact positions of 16 zone-edge CP phonons. In conjunction with the triply degenerate zone-center mode, this set of phonons then provides the basis for predicting the positions of second-order optical features through simple summations. When the selection rules are taken into account, the procedure yields excellent results, not only in terms of CVD-diamond ir spectra, but also in regard to earlier measurements of the intrinsic two-phonon absorption coefficient of type-IIa natural diamond [J. Hardy and S. Smith, Philos. Mag. 6, 1163 (1961)] and the second-order polarization-dependent Raman spectra recorded by Solin and Ramdas.

Introduction to the design of transconductor-capacitator filters

Abstract: Preface. 1. Introduction. 2. Filter Topologies and Terminology. 3. Biquad Filters. 4. Gyrator Filters. 5. State-Variable Filters. 6. Dealing with Floating Capacitors. 7. The Non-Ideal Transconductor. Part I: Parasitic Capacitances and Mismatches. 8. The Non-Ideal Transconductor. Part II: Output Impedance. 9. The Non-Ideal Transconductor. Part III: Non-Linearity. 10. Tuning of Transconductors. 11. Design of the gm-C Integrator. 12. Design of a gm-C Filter. 13. Tuning of gm-C Filters. Index.

Laser radar system with phased-array beam steerer

Abstract: An optical beam steering device for use in a single-aperture laser transceiver system provides deflection of the transmitted and received beams in two planes, while maintaining the distinctive identities of each channel respective to their polarizations. The invention utilizes four single-dimensional beam deflecting devices, two for each orthogonal linear polarization of the two transceiver channels, one of these for each steering axis. In addition, a 90° polarization rotator and a quarter-wave plate are included in the arrangement of beam deflecting devices to satisfy the polarization requirements of these devices and of the transceiver channels. In a preferred embodiment, the beam deflecting devices comprise liquid crystal cells functioning as variable phase retarders, each of the cells comprising a first window having a common electrode, a second window having a multiplicity of electrodes in the form of electrically isolated, parallel stripes, and a layer of liquid crystal molecules intermediate the first and second windows. Means are provided for coupling a multiplicity of control signals individually between the multiplicity of stripe electrodes and the common electrode, thereby creating selectable local variations of refractive index in the liquid crystal layer.

Scan compensation for array antenna on a curved surface

Abstract: A low array antenna having transmit/receive (T/R) modules, which contain a digitally-controlled variable attenuator, for each of the two polarizations (horizontal and vertical) The array has a cylindrically curved surface which closely conforms to the shape of the fuselage of an airborne vehicle or another structure Each polarization feeds into an elevation beamformer apparatus which provides both a uniform taper and a Bayliss/Taylor taper As the beam is scanned in elevation, the amplitude taper is adjusted via the variable attenuator to control the taper of a sum pattern and thereby achieve low sidelobe far field sum patterns The same attenuators that are used for the sum pattern also feed a difference network The T/R module attenuators are set to yield the desired low sidelobe sum illumination for a desired elevation scan angle As the array is steered in elevation, the Bayliss difference taper is distorted since the fixed elevation beamformer cannot adjust the difference pattern for the new scan angle A T/R module is provided at each column of the array to combine the distorted Bayliss difference pattern with the compensated Taylor sum pattern output This combining permits the distorted Bayliss array illumination to be resymmetrized thereby producing a high quality, low sidelobe, compensated Bayliss far field pattern This apparatus provides for complete compensation of both sum and difference patterns with only a single attenuator at each element of the array and a simple monopulse feed network

Microwave oscillator with noise degeneration feedback circuit

Abstract: A microwave oscillator is shown to include an oscillator having an output and a control port and a feedback circuit disposed between the output and the control port of the oscillator. The feedback circuit includes a modulated laser, having an input and an output, the input responsive to a portion of a signal from the output of the oscillator and a photo detector having an input and an output, the input of the photo detector responsive to a signal from the output of the modulated laser delayed by a predetermined amount of time. The feedback circuit further includes a detector having a first and a second input and an output, the first input of the detector responsive to a signal from the output of the photo detector, the second input responsive to a portion of the signal from the output of the oscillator shifted in phase to be in phase quadrature with the signal at the first input of the detector and the output of the detector coupled to the control port of the oscillator. With such an arrangement, a microwave oscillator having improved FM noise performance than known microwave oscillators is provided.

Method for providing beam steering in a subaperture-addressed optical bean steerer

Abstract: A practical means for electrically addressing the extremely large number and high density of phase shifters needed for operation of an optical phased array beam steerer. The array of phase shifters is subdivided into identical subarrays which completely fill an optical aperture. All subarrays are connected electrically in parallel by electrically interconnecting corresponding electrodes of each subarray. Methods are disclosed herein for providing an enhanced number of beam steering positions for the subaperture-addressed beam steerer.

Continuous monitoring electrostatic discharge system

Abstract: A monitoring system is shown to include a connector, having an input path and a current return path, for connecting a two section wrist strap to said connector, said two section wrist strap, when affixed to an operator's wrist, would complete an electrical path between the input path and the current return path of the connector across the wrist skin surface. The monitoring system further includes a current source for providing an electrical current to the input path and a comparator for comparing a voltage at the input path to a high limit value and a low limit value and for providing an alarm signal whenever the voltage at the input path is not between the high limit value and the low limit value. With such an arrangement, an operator is ensured that a proper connection between the operator and ground is maintained thus significantly reducing the possibility of an electrostatic discharge harming an electronic component handled by the operator.

Gain control amplifier

Abstract: A temperature compensation circuit (26) is used to provide a reference signal in a feed forward gain control loop (28). With such an arrangement, gain control is provided wherein variations of an output signal of the amplifier circuit (10) due to changing characteristics of amplifier elements (12,18) of the amplifier circuit (10) caused by ambient temperature variation or a varying input signal level are minimized. Part of the amplified (12) input signal is supplied by a coupler (14) to a detector (20) followed by a low pass filter (22) that supplies one input of a differential amplifier (24) that receives the reference signal and supplies a control signal to a controllable attenuator (16).

Young's modulus and Poisson's ratio of CVD diamond

Abstract: The elastic modulus E of diamond is often set equal to 1/s11 equals 1050 GPa, which assumes that is does not vary much with orientation, and many authors use (upsilon) equals 0.2 as an appropriate average value of Poisson's ratio, which is incorrect. In fact, since the elastic constants of diamond are known with great accuracy, it is a straightforward matter to derive exact numbers for E and (upsilon) that take into consideration the stress direction, the intrinsic anisotropy, as well as the crystalline configuration. For CVD diamond deposits, we find that, in a first approximation, the Hershey-Kroner-Eshelby averaging procedures yields acceptable numbers, E equals 1143 GPa and (upsilon) equals 0.0691, which are quite compatible with available experimental evidence. Our measurements of the biaxial modulus, E' equals E(1 - (upsilon) ), made use of the bulge test method to characterize the elastic behavior of both microwave-power and hot-filament assisted CVD diamond films. High- quality deposits yield E' is congruent to 1180 GPa and E' is congruent to 1220 GPa for randomly orientated and (110) textured deposits, respectively: these results confirm that state-of-the-art deposits exhibit elastic properties that are in accord with the measured stiffnesses of natural single- crystal diamond. The residual hydrogen content strongly impacts the elastic behavior and appears to be responsible for the degradation of the modulus observed in this and previous work.

Broadband bipolar transistor distributed amplifier

Abstract: A distributed circuit includes a plurality of pairs of cascode coupled first and second transistors with each transistor having base, emitter, and collector electrodes. The first transistor of each pair is disposed to have a first one of emitter and collector electrodes coupled to a reference potential and the second one of said transistors of each pair is disposed to have the base electrode coupled to a reference potential with the second one the collector and emitter electrodes of the first transistor of each pair being coupled to the emitter electrode of the corresponding second transistor of each pair. The network further includes an input propagation network disposed to successively couple the base electrode of each one of the first transistors of each pair of transistors to an input terminal and an output propagation network disposed to couple the collector electrodes of each one of the second transistors of each one of the pair of transistors to an output terminal of the circuit.

Fracture strength measurement of filament assisted CVD polycrystalline diamond films

Abstract: The fracture strength of polycrystalline diamond films deposited by filament assisted chemical vapor deposition in the thickness range of 3.5 to 160 μm is investigated. Using a burst pressure technique, the fracture strengths of circular diamond film specimens are calculated. An average fracture strength of 730 MPa for nine samples was computed. This value is in good agreement with published strengths of microwave plasma deposited diamond films, comparable to other high strength materials, and within an order of magnitude of the fracture strength of bulk natural diamond. The average fracture strength of the fine-grained substrate interface appears consistently higher than that of the coarse-grained diamond growth surface.

Tapered thermal substrate for heat transfer applications and method for making same

Abstract: A tapered thermal substrate for transferring heat generated from a heat source to a heat sink comprising a composite core of parallel layers of thermally conductive fibers, the core having a tapered edge that maximizes fiber end exposure to the heat source or sink. The tapered edge is comprised of at least one angled surface formed by machining the composite core. A copper thermal tab is plated to each angled surface and machined to a desired size and shape to provide a contact surface for the heat source or sink and a means for facilitating transfer of generated heat to and from the fiber ends. A flashing of a thin coating of copper and nickel over the composite core and each copper thermal tab is also provided to environmentally seal the composite core.

Optical beam steerer having subaperture addressing

Abstract: For electrically addressing the extremely large number and high density of phase shifters (30,50,42) needed for operation of an optical phased-array beam steerer (52), the array of phase shifters is divided into identical subarrays (38) which completely fill an optical aperture. All subarrays (38) are connected electrically in parallel by electrically interconnecting corresponding electrodes (32) of each subarray (38). Thus, the number of external electrical leads (36) required for addressing the fully array is reduced to the number of phase shifters in a single subarray (38).

One watt, very high efficiency 10 and 18 GHz pseudomorphic HEMTs fabricated by dry first recess etching

Abstract: The authors report 10- and 18-GHz power performance of double recessed 1.2-mm periphery pseudomorphic high electron mobility transistors (PsHEMTs). They have obtained demonstrably better uniformity in performance than conventionally fabricated PsHEMTs. This was accomplished by incorporating a new approach to recess formation using selective reactive ion etching of the first recess in a double recessed structure. The critical first recess was formed with exceptional uniformity using dry etching and an AlGaAs etch stop layer. Simultaneous power, gain, and power-added efficiency, representative of many devices, are summarized. >

Spectral purity of acoustic resonator oscillators

Abstract: The spectral purity of state-of-the-art oscillators that use acoustic resonators in the frequency range of 5 to 500 MHz is surveyed, with the primary emphasis placed on oscillators that use bulk acoustic wave and surface acoustic wave devices on single crystal quartz. The phase noise characteristics of low-noise oscillators are analyzed in the context of Leeson's model of feedback oscillator phase noise, and particular attention is given to flicker frequency noise levels and white phase noise floors. Procedures and methods for reducing phase noise levels are discussed along with an analysis of reported attempts to obtain improved spectral purity. >

Theory of low-field loss in partially magnetized ferrites

Abstract: Low-field loss in partially magnetized ferrites has important implications for the design of broadband circulators and other microwave devices. A quantitative theory of this effect has been developed that takes the inhomogeneity of the DC bias field into account. The theory is specifically applied to a calculation of the transmission loss for a microstrip line on a rectangular ferrite platelet. >

Apparatus and method for making microwave popcorn

Abstract: Apparatus and method for popping high yield popcorn using a bag having a substantially rectangular cross section as manufactured using a conventional bag machine. A base supports the bag on edge with at least one joining panel being inclined such as, for example, at 45°. Whether the bag is initially unfolded or unfolds as a result of internal pressure caused by some kernels popping, a horizontal elongated V-shaped trough is formed as the lower-most region of the bag due to the supporting orientation of the base. Kernels form in a clump in the nadir of the trough thereby enhancing the yield of the popping, and kernels disturbed from the clump by popping kernels are directed back to the clump by the inclined walls of the bag.