Showing papers by "Raytheon published in 1993"

One-time logon means and methods for distributed computing systems

Abstract: Apparatus and methods of authenticating users in a distributed networked computing system (10). The system (10) may comprise a central server (12) embodiment that includes a file (19) wherein IDs and encrypted passwords (30) are stored, or a distributed system embodiment where IDs and encrypted passwords (30) are stored in files (19) at each respective computer in the system (10). A multiple logon procedure (16) and secure transport layer protocol are used with a user's communication software and network communication software. When a user desires to use a particular computer (13), logon requests are processed by the multiple logon procedure (16) and it accesses the stored file (19) that contains the user's ID and encrypted password, decrypts the password (30), accesses the remote computer (13), and logs the user onto that computer (13). In the central server system all IDs and encrypted passwords (30) are stored on a single computer (the server (12)) that controls access to the entire distributed system (10). Once access is granted to a particular user, nonencrypted passwords (30) are transmitted to the remote computers (13), since the server (12) controls the entire system. In the distributed version, password files (19) are stored in all networked computers (13), and once a user logs on to a computer (11), if the user wishes to use services at a second computer (13), the authentication information is forwarded to the second computer (13) using the secure transport layer protocol to protect its integrity, and after receiving the authentication information, it is compared with authentication information for the same user stored in the second computer (13). If the authentication information matches, the user is logged onto the second computer (13).

Process improvement and the corporate balance sheet

Abstract: The Software Engineering Initiative, process-improvement program undertaken by the Software Systems Laboratory in Raytheon's equipment division in mid-1988 is reviewed. The three phases of the program are the process-stabilization phase, in which the emphasis is on distilling the elements of the process actually being used and progressively institutionalizing it across all projects, the process-control phase, in which emphasis shifts to instrumenting projects to gather significant data and analyze the data to understand how to control the process, and the process-change phase, in which the emphasis is on determining how to adjust the process as a result of measurement analysis and how to diffuse the new methods among practitioners. It is shown that the process-improvement initiative has improved the equipment division's bottom line, increased productivity, and changed the corporate culture. Much of the savings came from reducing rework. >

Dual polarized dual band antenna

Abstract: An antenna system is described including a reflector antenna, responsive to radio frequency signals at a first frequency, having a first reflector surface, a second reflector surface and a Cassegrain feed. The antenna system further includes an array antenna having a plurality of antenna elements responsive to radio frequency signals having a second different frequency, wherein a center element is in a common location with the feed of the reflector antenna. With such an arrangement, an improved dual band antenna system is provided. By providing the center element of the array antenna in a common location with the feed of the reflector antenna, a dual band radio frequency antenna system is provided which is more compact with improved radiation characteristics than known similar configured antennas.

Fatigue of ferroelectric PbZrxTiyO3 capacitors with Ru and RuOx electrodes

Abstract: The fatigue behavior of ferroelectric PZT capacitors with Ru and RuOx electrodes was studied. These capacitors show no sign of fatigue out to 1 X 1011 cycles, in sharp contrast to the degradation typically observed with Pt electrodes. Compared to Pt electrodes, the initial polarization was lower, but after fatiguing the polarization was comparable to or larger than that for Pt electrodes. Differences in polarization in response to switching and nonswitching pulses greater than 10 μC/cm2 were observed at 1 X 1011 cycles.

Improved equivalent circuit for determination of MESFET and HEMT parasitic capacitances from "Coldfet" measurements

Abstract: An improved equivalent circuit for MESFET and HEMT devices under zero drain bias pinched-off conditions is proposed. Parasitic gate and drain capacitances evaluated from low-frequency Y parameters using this circuit are approximately equal under conditions where equality would be expected from bond pad geometry considerations. In contrast, the previously used circuit considerably overestimates parasitic drain capacitance. >

Applications look at the use of liquid crystal writable gratings for steering passive radiation

Abstract: Liquid crystal writable grating technology is being developed for beam steering in laser radar systems. We consider the ability of writable gratings to steer broad-spectral-band radiation for use in passive sensors. We find that there is potential for these devices in microscan systems because there is little or no dispersion for the small scan angles required in microscanning. The dispersion that is present is less than the resolution of the sensor considered here. For large angle steering we find that dispersion correction or a narrowing of the spectral bandwidth is required. The degradation in sensitivity resulting from narrowing the spectral bandwidth is considered. We find that a high-quantum-efficiency step-stare sensor with a two-dimensional focal plane array responsive over a narrow spectral width can achieve the same sensitivity as current linear scanning sensors while being able to steer the field of view (FOV) over a larger field of regard with no moving parts. Approaches for dispersion correction and postdetection correction are discussed. A promising approach for steering a narrow FOV with broad spectral content and good resolution is described.

A rigorous yet simple method for determining stability of linear N-port networks [and MMIC application]

Abstract: The authors describe a technique for easily calculating normalized determinant function using return ratios. It is shown that an elegant yet simple relationship exists between the return ratios of each dependent source in a linear network and Platzker's normalized determinant function. Using this relationship, the stability (or instability) of linear N-port networks containing any number of active devices can easily be determined using commercially available circuit simulators. An example is shown where this new technique correctly predicts instability in a GaAs MMIC power amplifier. >

Power converter having optimal dynamic operation

Abstract: A DC to DC, fixed frequency, Buck family power converter having a first feedback control loop for regulating output current or output voltage depending on the operational mode selected, a second feedback control loop for current mode control and a third feedback control loop for providing improved dynamic response for all conditions of line and load. The third feedback control loop senses the output voltage and generates a variable ramp signal having a slope (M) which is proportional to the converter output voltage. By maintaining as a constant (K) a ratio of the variable ramp slope (M) to the falling slope (M 2 ) of a voltage representation of the inductor current in an LC network of the Buck regulator or K=M/M 2 , improved dynamic operation of the power converter results for a plurality of output voltages particularly improving output ripple rejection and minimizing effects of injected noise in the current mode control loop.

An AlGaAs/InGaAs pseudomorphic high electron mobility transistor with improved breakdown voltage for X- and Ku-band power applications

Abstract: The authors determined that RF drain current degradation is responsible for the poor power performance of wide-recessed pseudomorphic high-electron-mobility transistors (PHEMTs). A model based on surface states was proposed to explain this phenomenon, which then led to the use of charge-screen layers and a double-recessed gate process to suppress surface effects. Combined, these two modifications increased the device's gate-drain reverse breakdown voltage without causing a degradation in the transistor's RF drain current. This allowed the simultaneous achievement of high power-added efficiency and high power density which established a new performance record for power PHEMTs at X- and Ku-bands. Delay time analysis of single- and double-recessed PHEMTs revealed that the benefit of a larger breakdown voltage in the latter device design came at the cost of a larger drain delay time. Drain delay accounted for 45% of the total delay when the 0.35- mu m double-recessed PHEMT was biased at V/sub ds/=6 V. >

Instabilities diagnosis and the role of K in microwave circuits

Abstract: Many papers and textbooks and the leading CAD (computer-aided design) packages state that a two-port is stable if and only if K>1 and mod Delta /sup s/ mod >

A new compact wideband balun

Abstract: A novel wideband balun has been developed for MMIC (monolithic microwave integrated circuit) applications Simple RF reflection and coupling principles are used to achieve a wideband performance in a simple microstrip configuration The design was intended for 8- to 18-GHz wideband mixer applications According to the predicted performance the insertion loss was better than 2 dB from 7 to 19 GHz, the amplitude balance was less than 1 dB, and the phase balance was less than 5 degrees from the 180 degrees phase difference Experimental results show very good agreement with the predicted performance >

Method for manufacturing fiber-reinforced parts utilizing stereolithography tooling

Abstract: A method of manufacturing a three-dimensional fiber-reinforced part utilizing the single-tool method of stereolithography. The tool is fabricated by designing the tool on a computer-aided design system and curing successive layers of a fluid medium via a computer-controlled irradiation source to form the three-dimensional tool. The desired part is generated by applying layers of resin-wetted fabric to the tool, curing the fabric on the tool, removing the tool from the designed part and cleaning, trimming and inspecting the designed part.

Semiconductor structures having dual surface via holes

Abstract: A semiconductor structure having an active layer formed over a first surface of a substrate. The semiconductor structure includes an electrode formed over a first surface of the structure. A conductive layer is formed over a second surface of the substrate. A conductor section passes through the semiconductor structure between the electrode and the conductive layer. The conductor section includes two conductive elements, one having a first end connected to the electrode and a second end terminating in the semiconductor structure; and the other conductive element having a first end connected to the conductive layer and a second end connected to the second end of the first conductive element. The second end terminates at, or in, an etch resistant layer disposed in the semiconductor structure between the active layer and the substrate. The method for forming the conductive sections includes etching the second via hole from the second surface of the substrate until the etching reaches an etch resistant layer. The walls of the second via hole and exposed portions of the conductive material covering the walls of the first via hole are covered with an electrically conductive material.

Radio frequency antenna

Abstract: An improved dual polarized antenna element for use in planar array antennas. The antenna element includes a conductive sheet having a forwardly positioned notch and a pair of spaced rearwardly extending slot portions formed therein. The notch is adapted for coupling radio frequency energy between free space and the antenna element and the pair of slot portions are electrically coupled to the notch. A power divider/combiner is provided and is preferably interconnected with a power combiner/divider through branches of equal phase length. With this arrangement, reactive power divider induced off-axis scan blindness caused by an odd mode coupled field is prevented. Additionally, an antenna module comprising a pair of such antenna elements disposed in intersecting relationship is provided with a coincident phase center.

Pin driver amplifier

Abstract: A pin driver amplifier having a complementary pair of transistors with a pair of resistors coupled between the respective emitters. A node between the resistors is coupled through an output series resistor to an output terminal adapted for connection of a transmission line that conducts driver pulses of predetermined voltage levels and timing to a device under test. A capacitor is tied between the emitters to provide a substantially constant reverse termination impedance for the transmission line thereby reducing reflections. Also, an RC network is coupled between the output terminal and ground to further reduce reflections. The amplifier transistors are driven by respective buffer transistor emitters that are tied together by a capacitor to make the positive and negative going drive capabilities for the amplifier transistors more equal. Further, capacitors are coupled between the amplifier collectors and ground to provide a bypass for parasitic inductance in the supply voltage wires.

Method for forming deep conductive feedthroughs

Abstract: An interconnect layer (40) for interposing between two active circuit layers of a multi-chip module (50). The interconnect layer includes a layer of silicon (14) having first surface and second surfaces. A first layer of dielectric material (16) is disposed over the first surface and a second layer of dielectric material (12) disposed over the second surface. The interconnect layer includes at least one electrically conductive feedthrough (42) that is formed within an opening made through the layer of silicon. The opening has sidewalls (22) that are coated with a dielectric material (24) and an electrically conductive material for providing a topside contact (26). A second contact (28) is formed from the backside of the silicon layer after removing the substrate (10). In accordance with the invention, the sidewalls have a slope associated therewith such that an area of the opening is larger at the first surface of the silicon layer than at the second surface of the silicon layer, thereby improving the contact metal step coverage. The silicon layer is comprised of silicon and has a thickness in the range of approximately 10 micrometers to approximately 50 micrometers. The opening is etched through the silicon layer with KOH to provide an inwardly sloping sidewall profile having an angle that is approximately equal to 54.7 degrees.

Modular aerodynamic gyrodynamic intelligent controlled projectile and method of operating same

Abstract: A spinning projectile is described including a roll rate sensor for providing a spin frequency signal, a nutation frequency signal and a precession frequency signal and a seeker for providing a boresight angle signal. The spinning projectile further includes a torquer assembly, responsive to a control signal, for selectively providing a force in a desired lateral direction and a digital signal processor, responsive to the spin frequency signal, the nutation frequency signal, the precession frequency signal and the boresight angle signal, for providing a control signal to the torquer assembly to control the desired direction of the force. With such an arrangement, a projectile is provided having greater maneuverability wherein an increase in maneuver footprint is obtained by having the maneuver force equal the sum of the rocket force and the body force rather than being a difference as in known projectiles.

Series resonant converter having a resonant snubber

Abstract: A fixed frequency, series resonant converter having a resonant snubber comprising an inductor and capacitor connected across a tank circuit of the converter. An optimum amount of inductance in the resonant snubber minimizes the degree of "shoot-thru," or conduction through a body-diode within a transistor switch of the converter caused by ringing, which allows for nearly sinusoidal current to be provided to a full bridge high voltage rectifier enabling the power converter to operate at a higher frequency. An alternate embodiment applies the resonant snubber only across a selected transistor switch.

Interactive computerized witness interrogation recording tool

Abstract: An interactive computerized witness interrogation recording tool (10) which provides a way to rapidly convert verbal descriptions of objects and events into graphical displays. The verbal descriptions are entered into the interrogation recording tool (10) by an operator utilizing a keyboard (16), graphical input device (18) and an icon based control panel (32) in a display device (30). Commands utilized by the operator are stored in a command library (44) or originate from a textual algorithm (54) which can generate a time sequence of objects and events based on the statements. The representation of the object and events are stored in a 3D geometry database (46) which is displayed by using a geometry display generator (52) under control of a command interpreter (42) and on the display device (30). Because the display is created in real time, the individual providing the statements is able to immediately confirm or deny the accuracy of the representation as it is being constructed in its various stages. Further, the textual algorithm (54) can be configured to confirm or deny the plausibility of the statements made.

Microstructure and method of making such structure

Abstract: An integrated circuit having a semiconductor layer having formed therein a electronic circuit. An electrical device, electrically connected to the electronic circuit, has a corrugated platform supported over, displaced from, and integrally formed with, the substrate. In a preferred embodiment the electrical device is a bolometer and the electronic circuit is a read out circuit for the device. The platform includes a surface member and a leg, a proximate end of the leg being disposed on the substrate and the distal end being elevated from the substrate and terminating at the surface member. Preferably the leg and the surface member are corrugated. The supporting surface has a corrugation parallel with the leg. The surface member is supported, as a corrugated air-bridge, over the surface of the substrate by corrugated legs. The temperature sensitive resistive material is formed over the corrugated surface member. Electrical conductors are formed over the legs, one end being in contact with the electrical contacts and the other ends being connected to the portions of the temperature sensitive resistive material adjacent the distal ends of the legs.

Electro-optical target and background simulation

Abstract: A computer-based thermal scene simulation system and method for generating synthetic images to facilitate the design and test of missile-borne electro-optical seeker systems. A scene is comprised of objects and a background selected from available target and background database files. Stationary or mobile objects are modeled by combining small planar facets to cover their three dimensional surface. Each facet is associated in the database files with the thermal and optical properties of the surface that is modeled. The background is modeled on the interior surface of a pyramid defining the extent of the scene, with the floor of the pyramid representing the surface of the earth and the sides of the pyramid representing an above horizon image. The pyramid surface is then divided into triangular facets that represent portions of the surface. Each facet is assigned a uniform texture selected from the background database files comprising background materials. The simulation is designed to be used with missile six degree of freedom simulations, and generates images as seen by a missile seeker based on instantaneous seeker line of sight, seeker position, seeker orientation, object orientations and positions, and background. Seeker-to-object aspect angles and range closure rates are processed by an image generation procedure. A projected image is then convolved with the optical point spread function of the seeker to generate a radiance distribution on the focal plane of the seeker. Sampling of the focal plane radiance distribution is modeled and an output data stream from the seeker to a signal processor is generated.

Wide dynamic range non-uniformity compensation for infrared focal plane arrays

Abstract: A method and apparatus for non-uniformity compensation for infrared focal plane arrays in an infrared imaging device (10) including a calibration operation and a correction operation. The calibration operation measures the response (24) generated by the detector elements (14) in the focal plane array (16) to a wide range of known signal flux levels of infrared radiation (22) produced by a uniform black body under controlled conditions. The responses (24) are then stored as a digital video signal (27) in a look-up table memory (38). The correction operation achieves the near real-time compensation of a second response of the detector element (14) to the signal flux level of infrared radiation (22) produced by objects in the field of view surveyed by the imaging device (10) by comparing the second response to the stored digital video signals (27) and interpolates the second response to a corrected digital video output signal (31).

Method of manufacturing a ferroelectric device using a plasma etching process

Abstract: A method of patterning a film of PZT material comprises the steps of providing a mask over a selected surface portion of the PZT material; and, plasma etching unmasked portions of the thin film material. The method includes the steps of: introducing a gas mixture of halogenated gases into a chamber; ionizing the gas mixture into a plasma in the chamber by imposition of an electric field across the introduced gaseous mixture, chemically reacting the ionized gaseous mixture, chemically reacting the unmasked portions of the lead zirconate titanate thin film material to selectively remove such exposed portion of the thin film material. The gas mixture is a mixture of a chloride and a compound of fluorine. Preferably the compound of fluorine is a halocarbon or fluorocarbon. In particular, the fluorocarbon is a trifluoromethane, CHF 3 , and the chloride is boron trichloride BCl 3 .

Pyramidal horn gain calculation with improved accuracy

Abstract: Previously published methods for pyramidal horn gain calculation have used an approximate expression for the path length error that gives rise to aperture quadratic phase error. In this study pyramidal horn gain is calculated without approximating the path length error. These improved accuracy gain calculations give results equal to the previous approximate calculations for large apertures (A or B>50 lambda ) or small peak aperture phase error in wavelengths (S or T 0.6) the improved accuracy method can yield lower gain than the previous calculations, especially for an E-plane flare. >

Dimple interconnect for flat cables and printed wiring boards

Abstract: An electrical connector assembly (10) comprises first and second electrical connectors (12 and 14) and/or a printed wiring board having electrical conductors thereon ending in termini. Dimples (36 and 38) are provided on the termini and are configured with matable surfaces of concave and convex configurations to provide conforming concave-convex contacts with one another for electrical coupling of the two connectors. The dimples also provide self-alignment between the matable electrical connectors.

Transmission of phonons through grain boundaries in diamond films

Abstract: With the advent of new growth techniques, research on the properties of diamond has undergone a rebirth in recent years. The capability of producing very high quality polycrystalline films has greatly enhanced the prospects of exploiting the extreme physical properties of this substance. One area of great interest has been the thermal conductivity K of synthetically produced diamond. Vapordeposited material is now made routinely with room temperature thermal conductivities up to 85% that of bulk single crystals. It is not yet clear, however, what processes limit the conductivity to values below that of single crystal material. Some time ago, it was recognized”2 that the polycrystalline nature of the film morphology could provide some limitation to the thermal conductivity at and even above room temperature. More recently, detailed studies of the anisotropy of the thermal conductivity3 as well as a through-the-thickness gradient in K’,~ have provided some indirect evidence of the influence of grain boundary scattering. On the other hand, it has also been shown6 that very low levels of defects within the grains, most likely associated with small concentrations of nondiamond carbon, are capable of strongly degrading the thermal conductivity over the temperature range 20-300 K. Separation of the influence of grain boundaries and other defects is complicated by the fact that samples with smaller grains usually have more defects since the latter tend to be concentrated at grain boundaries7 One can, in principle, differentiate to some extent between the effects of intragrain defects and grain boundaries on the heat conduction by measuring K

A double-recessed Al/sub 0.24/GaAs/In/sub 0.16/GaAs pseudomorphic HEMT for Ka- and Q-band power applications

Abstract: A double-recessed 0.2- mu m-gate-length pseudomorphic HEMT (PHEMT) has been demonstrated with 500 mW of output power (833 mW/mm of gate periphery), 6-dB gain, and 35% power-added efficiency (PAE) at 32 GHz. At 44 GHz, the device exhibited 494 mW of output power (823 mW/mm), 4.3-dB gain, and 30% PAE. This level of performance is attributed to excellent MBE material, optimized epitaxial layer design, and the use of individual source vias and of double recess with tight channel dimensions. Excellent 3-in-wafer uniformity was also observed: DC yield was greater than 95% and the interquartile range for all DC parameters was less than 20% of the median value (most are significantly lower). >

Thin film resistor and method of fabrication

Abstract: A method of fabricating a thin film resistor includes a step of sputter depositing a thin film of resistive material such as a chromium diboride compound on an insulative substrate using an argon sputter gas having a percentage of dopant such as nitrogen selected to optimize a trade off between desirably increasing the thickness of the film and undesirably increasing the temperature coefficient of resistance. A cap layer having a solid diffusant such as free chromium is deposited over the thin film of resistive material. The cap layer serves to protect the thin film of resistive material during subsequent patterning of conductors using wet etching, and also the solid diffusant diffuses into the resistive material during subsequent thermal treatment to drive the temperature coefficient of resistance back down.

Electroacoustic transducer seal

Abstract: A compliant cover for use with acoustic source transducers includes a rubber boot bonded to a shell of the transducer. The cover has a groove molded within a surface thereof to allow the shell to expand and contract with reduced resistance. Conventional transducers having rigidly mounted covers disposed on the shell which resist the motion of the shell and decrease the overall efficiency of the transducer.