Showing papers by "Raytheon published in 1989"

The tapered slot antenna-a new integrated element for millimeter-wave applications

Abstract: Tapered slot antennas (TSAs) with a number of potential applications as single elements and focal plane arrays are discussed. TSAs are fabricated with photolithographic techniques and integrated in either hybrid or MMIC circuits with receiver or transmitter components. They offer considerably narrower beams than other integrated antenna elements and have high aperture efficiency and packing density as array elements. Both the circuit and radiation properties of TSAs are reviewed. Topics covered include: antenna beamwidth, directivity, and gain of single-element TSAs; their beam shape and the effect of different taper shapes; and the input impedance and the effects of using thick dielectrics. These characteristics are also given for TSA arrays as are the circuit properties of the array elements. Different array structures and their applications are also described. >

Method of recognizing patterns

Abstract: In a method of identifying an object from a digitized image that is particularly applicable to the classification of aircraft, the digitized image (152) of an unknown object is represented as a set of radial vectors (150₁, 150₂, ..). The vectors (150) are normalized and then compared with a library (18) containing normalized digitized images of known objects. The unknown object is thereby identified as being similar to the known object corresponding to the library image most closely matching the image of the unknown object. A score for the comparison of the unknown object silhouette with a known silhouette is obtained by subtracting the radial vectors of the known silhouette from those of the unknown silhouette, and summing the differences. The closest match is the smallest sum of difference.

A novel MMIC active filter with lumped and transversal elements

Abstract: An active filter structure is developed, fabricated, and demonstrated as a monolithic microwave integrated circuit (MMIC). This filter structure makes use of both lumped elements and active transversal elements. The filter uses lumped elements to achieve a basic bandpass filter response, and transversal elements to sharpen the bandpass characteristic. Active elements are included to overcome the high loss of MMIC lumped elements. This miniature MMIC filter has a passband of 9.8-11.1 GHz with 2-dB loss and better than 30-dB rejection 1.1 GHz from either passband edge. >

Systematic study of fields due to extended apertures by Gaussian beam discretization

Abstract: Gaussian beams are used as basis elements in field representations. To gain insight into how the choice of beam parameters affects the final representation, a systematic study for the simple test case of a one-dimensional linearly phased cosine-aperture distribution has been undertaken. By successively adding individual displaced and/or tilted beams with large, narrow, or matched waists, one can assess how the elements in various portions of the lattice contribute to the build-up of the actual field in the aperture, near zone, and far zone. Adding enough beams always guarantees homing in on the exact solution, as is verified here by independent comparison. Different beam choices imply different modeling of the radiation process. The understanding gained thereby is helpful for selecting beam parameters in subsequent applications where it is necessary to balance requirements of good convergence, ease of computation, and ability to track the beams through perturbing environments like a radome. Indications are that the narrow beams provide the most robust and versatile formulation to deal with these generalized conditions. >

Waveguide excited enhancement and inherent rejection of interference in a subharmonic mixer

Abstract: A subharmonic mixer is shown to comprise two pairs of matched antiparallel GaAs diodes disposed on a dielectric slab and operative with microstrip circuitry. By suppressing the fundamental mixing products, mixing the radio frequency signal with the second harmonic of a local oscillator (LO) signal and using relative phase differences of the LO signals in the two pairs of diodes, undesirable effects from spurious signals are minimized.

Deflector for an optical beam

Abstract: An optical beam phase shifter includes a liquid crystal cell (20) having an optically-transparent common electrode (30) on a first window (22) and a multiplicity of parallel stripes electrodes (32) on the second window (26). A multiplicity of control signals are applied between the individual stripe electrodes (32) and the common electrode (30), thereby creating local variations of the refractive index of the liquid crystal molecules (24), which variations cause differential phase shifts across the cross section of a light beam incident thereon. The control signals are applied to contact pads (36) affixed to an external surface of the liquid crystal cell (20), which contact pads (36) underlie a plurality of the stripe electrodes (32). A multiplicity of conductors (34) extend through a transparent insulating layer (40) to couple the control signals to the stripe electrodes (32). The stripe electrodes (32) are optically-transparent, and the incident beam is reflected from the contact pads (36). In another embodiment, the stripe electrodes are reflective, and the incident beam is reflected therefrom.

R. f. switching circuits

Abstract: An advanced MESFET switching structure which includes an interdigitated source region and an interdigitated drain region, also includes a gate electrode region disposed between adjacent portions of the interdigitated source and drain regions having a series gate electrode in Schottky barrier contact therewith. The use of the series connect gate electrode rather than conventional parallel coupled gate fingers eliminates the need for an airbridge overlays to interconnect the source regions as in a conventional MESFET transducer. Moreover, the topography permits smaller MESFET structures and thus higher integration of circuits employing the advanced MESFET switch structure. The smaller transistors will also have lower parasitic reactances. In a preferred embodiment, all interconnections for drain, gate, and source electrodes are disposed on the active layer portion of the transistor providing an even smaller transistor structure.

Sensor elements in multilayer ceramic tape structures

Abstract: A structure formed of a plurality of sheets which are laminated and fused together includes at least one sintered ceramic sheet formed from thermally fusible tape A sensor element, such as a cantilever, circular diaphragm, rectangular diaphragm supported at least two sides, or microbridge, is formed as a part of the ceramic sheet A hole may be formed through one of the sheets adjacent to the ceramic sheet to expose the sensor element to an ambient environment which is to be sensed Electrical signals corresponding to a physical change in the sensor element such as stress or displacement are generated by piezoresistor, variable capacitor, photodetector, or the like attached to or formed on the sensor element, which is interconnected with a metallization pattern formed on at least one of the sheets The thickness of the sheets is highly uniform, thereby producing sensor elements with precisely reproducible thicknesses and mechanical properties

A novel MMIC active filter with lumped and transversal elements

Abstract: An active filter structure is described and demonstrated as a monolithic microwave integrated current (MMIC). The filter structure makes use of both lumped elements and active transversal elements. The combination of lumped and transversal elements provides performance superior to that of a filter made of lumped elements alone and is much smaller than a filter made of transversal elements alone. This miniature MMIC filter has a passband of 9.8-11.1 GHz with 2-dB loss, and better than 30 dB rejection 1.1 GHz from either passband edge. This level of performance could not have been achieved on a conventional 4-mil-thick GaAs MMIC with only passive lumped elements. >

Shelf track lighting

Abstract: A shelf track lighting for improving illumination of devices such as refrigerators or freezers. Coupled to the shelf is a lamp and a supporting brackets. The brackets engage with vertically positioned standards which are mounted to the rear wall of the device. Power is provided to the lamp through the standards and the brackets so that the lamp may be illuminated when the shelf and lamp levels are adjusted.

Programmable volume dispensing apparatus

Abstract: A programmable volume dispensing apparatus having a positive displacement metering pump for dispensing varying amounts of high viscosity fluids such as soldering paste. The metering pump comprises a positive displacement metering pump and a digitally driven drive motor under programmable control. The drive motor is connected to the volume adjustment of the pump via a chain and sprocket mechanism. The chain and sprocket mechanism adjusts a stop which controls the stroke of the pump and the volume of fluid dispensed. In an alternate embodiment a flexible rotary drive shaft controls the stroke of the pump and the volume of fluid dispensed. Different volumes of solder can be dispensed to different areas and shapes of pads on a circuit board in accordance with preprogrammed dispensing commands.

Polyimide thermal isolation mesa for a thermal imaging system

Abstract: A mesa (31) is formed from polyimide (or a similar polymer material) to achieve a high thermal resistance. In an exemplary thermal imaging application, an array of thermal isolation mesa structures (30) are disposed on an integrated circuit substrate (20) for electrically connecting and bonding a corresponding focal plane array (5) of thermal sensors (10). Each mesa structure (30) includes a polyimide mesa (31) over which is formed a metal conductor (32) that extends from the top of the mesa down a mesa sidewall to an adjacent IC contact pad (22). When the focal plane array (5) is bonded to the corresponding array of thermal isolation mesa structures (30), a thermally isolated, but electrically conductive path is provided between the sensor signal electrode (16) of the thermal sensor (10) and the corresponding contact pad (22) of the integrated circuit substrate (20).

Higher order transverse mode suppression in surface acoustic wave resonators

Abstract: A technique for adjusting the frequency of odd mode transverse waves propagating in a SAW device is described. A pair of localized regions of frequency determining trimming material are deposited onto selected portions of a surface wave propagating surface, to provide localized regions on said surface where the odd order transverse mode has energy maxima. These regions change the acoustic properties and hence the velocity characteristics of the surface wave propagating surface in said regions. The frequency of the odd mode transverse wave is changed accordingly and is preferably changed to match that of the fundamental transverse propagating wave. This decreases the insertion loss of the device at the fundamental frequency and eliminates the odd mode transverse wave propagation characteristic within the operating frequency range of the resonator. In a preferred embodiment, the SAW device further includes an acoustically matched piezoelectric transparent cover disposed over the surface wave propagating surface having disposed thereon a trim pad which is selectively removed to provide the localized regions and thus the localized alterations in the acoustic properties of the surface acoustic wave device.

Residual phase noise measurements of VHF, UHF, and microwave components

Abstract: The results are presented of residual phase noise measurements on a number of VHF, UHF, and microwave amplifiers, both silicon bipolar junction transistor (BJT) and GaAs field effect transistor (FET) based, electronic phase shifters, frequency dividers and multipliers, etc., which are commonly used in a wide variety of frequency source and synthesizer applications. The measurement technique has also been used to evaluate feedback oscillator components, such as the loop and buffer amplifiers, which can play important roles in determining an oscillator's phase noise spectrum. Use is made of an extremely low-noise, 500-MHz SAWRO (SAW resonator oscillator) as test source for residual noise measurements both close to and far from the carrier. Several interesting observations related to the residual phase noise properties of moderate- to high-power RF amplifiers, i.e. amplifiers with 1 dB gain compression points in the range of +20 to +33 dBm, are highlighted. >

Frequency domain measurements of indoor radio channels

Abstract: Frequency responses of the indoor radio channel for 128 locations in an office and a research laboratory are analysed. Some statistics on the number of fades arc determined. The cumulative distribution function (CDF) of the 3dB bandwidth of the frequency correlation function is presented, and experimental results relating the RMS delay spread of the channel and the inverse of the 3dB width of the frequency correlation function are given.

Fluid level sensor and controller

Abstract: A fluid level sensor for determining the amount of liquid in a container. Thin metal plates are placed parallely adjacent each other to form a capacitor cell coated with a non-hygroscopic film. The plates are mounted on the walls of the container containing fluid. As the fluid covers more surface area of the capacitor plates, the dielectric properties of the fluid increase the capacitance of the cell proportionally. The plates are connected to an oscillator whose output frequency varies with the change in container fluid levels. By monitoring these frequency changes, the container fluid levels of the fluid in the container can be controlled.

Method of laser marking metal packages

Abstract: A method of marking metal packages using a laser. The power in the laser beam is set to a predetermined value. The laser is then controlled in a four pass process with the Q-switching frequency of the laser, the speed at which the laser beam is moved across the package and the width of the lines drawn by the laser being set for each pass.

Gasket for a hollow core module

Abstract: A removable gasket for sealing an air-cooled hollow core module to the port of a chassis plenum for supplying cooling air includes an aluminum frame to which a thermally conductive elastomer seal is vulcanized. The gasket frame provides support for the seal and serves as a compression limiting stop for the seal. The gasket is held in alignment with the cooling channel of the hollow core module with attachment screws, greatly facilitating the gasket removal and repair of the module, and realignment with the chassis plenum port upon reassembly.

Self-zeroing amplifier

Abstract: A precision amplifier that, in response to digital inputs, zeros its offset voltage. The precision amplifier comprises a traditional amplifier; a current source controlled by a counter; a comparator; test switches; and control logic. A digital input, such as might be generated from a microprocessor, initiates the offset adjustment. The test switches disconnect the amplifier inputs from external package connections and connect the inputs together. The counter begins to count, changing the current produced by the current source at each count. The current from the current source is applied to the offset adjust circuit of the amplifier which changes the offset voltage as the current changes. The counter counts until the comparator indicates the offset voltage has been zeroed. Alternative embodiments allow the precision amplifier to adjust for offset introduced by circuitry connected to the input and the output of the precision amplifier.

Method of making standard electrodisplacive transducers for deformable mirrors

Abstract: A construction for electrodisplacive transducers for use in deformable mirrors in which the transducer is assembled from two or more segments of electrodisplacive material Each segment contains multiple stacked layers of electrodisplacive material which are separated from adjacent layers by electrodes During manufacture the segments may be individually tested and sorted by the stroke that they produce for a given electrical input signal applied to the stacked layers Segments are selected and fastened to each other so that the total stroke produced by the selected segments equals the stroke required from the actuator

Timing recovery scheme for burst communication systems having a VCO with injection locking circuitry

Abstract: A timing recovery apparatus for a burst mode communication receiver. The apparatus provides for optimum sampling and digitizing of received data at a plurality of data rates. In particular, a VCO is phase-locked to a local frequency reference prior to data being received. A reference timing preamble transmitted prior to the data is filtered and fed to the VCO causing it to injection lock such that the VCO becomes phase aligned with the preamble. The VCO is then permitted to "free run" during data transmission and continues to operate at substantially the same frequency. A synchronous divider and multiplexer, responsive to the VCO, allows selection of sampling clocks for the plurality of data rates. The divider is forced to a known state during VCO injection locking, to assure that the sampling clocks have maintained the proper phase for optimal sampling at the corresponding data rate. Further, means is provided to monitor the frequency of the VCO. Should the VCO frequency drift more than a predetermined amount an indication of such is produced.

Compact antenna range

Abstract: A miniature anechoic changer for testing antennas capable of producing radio frequency energy with a planar wavefront substantially uniform and free of distortion is shown. The chamber is comprised of a source antenna located in the near field of the test antenna radiating radio frequency energy having a wavefront with an amplitude having a distribution pattern that approximates (SIN X)/X and a lens having a focal point mounted such that the focal point of the lens is located in the center of the source antenna. As the source antenna radiates energy the energy passing through the lens is converted from a spherical wavefront to a planar wavefront substantially uniform and free of distortion.

Diode laser soldering system

Abstract: A laser soldering system wherein a plurality of laser beams are simultaneously directed to a plurality of spatially separate locations on a printed circuit board for simultaneously soldering Each of the laser beams is formed by combining the outputs of a plurality of fiber cables, each of which is connected to an individual laser diode

Impact resistant and tempered optical elements

Abstract: An impact resistant anti-reflection coating for an optical element mounted on an airborne system which mitigates damage to the optical element when the airborne system is flown through a high velocity droplet impact medium is described. In a first embodiment, the coating comprises a material having a relatively high modulus of elasticity deposited to a thickness equal to an odd multiple of a quarter of a wavelength of the wavelength radiation to be transmitted through the optical element. In accordance with a further aspect of the invention, the high modulus of elasticity layer may comprise a homogeneous mixture of a pair of high modulus elasticity materials as well as a composite layer comprising a first layer of a high modulus elasticity material and a second layer of a second modulus of elasticity material. In a second embodiment, the outer surface of an infrared material is strengthened by single diamond point turning the outer surface of the material to introduce into the surface a compressive layer. The compressive layer is characterized as having a plurality of furrows or grooves being spaced by compressed regions of material and having disposed under said furrows or grooves a compressed region of material.

Combination cooking cartridge

Abstract: A combination bake oven/steamer/broiler cartridge for cooking food on a cooktop. A heat source is placed on a pan within a cooktop frame. A cartridge is placed over the heat source and inserted into the pan. The heating device warms the cartridge. The cartridge can be selectively configured as a bake oven, steamer or broiler. To configure a bake oven, an adjustable rack is placed in the cartridge to hold the food. A cover is then placed over the cartridge to contain heat. To configure a steamer, water is added to the bottom of the cartridge. A steaming pan is then placed in the cartridge. The cartridge is then covered. The water is then heated to make steam. By substituting a ceramic or glass container for the steaming pan, the steamer functions as a warming device. To configure a broiler, a special cover containing heating elements is placed over the adjustable rack.

Disposable microwave package having absorber bonded to mesh

Abstract: A microwave heating susceptor for browning or searing packaged foods in a microwave oven. The susceptor is constructed from a thin metal mesh, and a microwave absorbing material applied to the metal mesh. To sear food, the suspceptor is placed in proximity to food in a microwave oven cavity. When the microwave oven is turned on, the susceptor heats to a high temperature, thereby browning and cooking the food.

A novel 4-18 GHz monolithic matrix distributed amplifier

Abstract: The authors describe the design, fabrication, and performance of a 4-18 GHz matrix distributed amplifier which incorporates a novel biasing scheme enabling the amplifier to run at higher voltages while drawing only half of the current of conventional multistage amplifiers having comparable gain levels. A voltage divider is used at the input of the FET pair to derive the gate bias, ensuring that both FETs are biased at the same point. This scheme enables the stages to be connected in cascade at RF frequencies and in cascode for DC biasing, thus conserving current. The amplifier shows >13 dB gain across the frequency band using a chip area of only 1.9 mm*2.1 mm. >

Dielectric resonator filter

Abstract: A dielectric resonator filter suitable for use at L-band includes a puck-shaped dielectric resonator attached directly to a dielectric substrate which is bonded to the cavity base in order to decrease vibration sensitivity while retaining a relatively high loaded Q of the dielectric resonator filter. The high value of Q is attained by the use of a low loss dielectric substrate with a dielectric constant sufficiently high that the electrical dimensions of the cavity approximate the free space or optimum model wherein the resonator is positioned at the center of the cavity. The disclosure describes a dielectric resonator filter having a loaded Q in excess of 6500 at 1.538 GHz with an insertion loss of 6 db, while maintaining a vibration sensitivity of 2.2×10 -8 G -1 . An arcuate segmented line comprising a plurality of tracks used as a coupling structure permits individual selection for each filter of the coupling, while not degrading the loaded Q value or the vibration performance.

Transient and intermittent fault insertion

Abstract: Fault insertion circuits under programmable control and resident in an integrated circuit (LSI or VLSI) (10) insert transient and intermittent fault classes in addition to a permanent fault class into functional logic (24) on such integrated circuit (10). Specific fault types programmable for each fault class include a stuck-open fault and bridging faults both wired-AND and wired-OR. The programmable fault insertion circuitry on each integrated circuit interfaces directly or indirectly with a BIT maintenance controller (12). In addition to verifying test software, a fault tolerant system's error detection and recovery circuits may be verified by fault insertion testing using the transient and intermittent fault insertions. The controller (12) inserts a fault (11) into the integrated circuit (10) with control and initialisation data words and monitors the effect of the fault on the functional logic (24). The fault control and initialisation data words are stored in timers (52, 54, 56), a fault word register (14), and an intermittent fault mode logic (60), and are decoded under the control of the controller (12) and a slaved timing and control generator (17) to load a fault type generator (16) which responds by supplying a fault type signal (FAULTn) to a fault insertion interface (18) which thereupon inserts the required fault into functional logic (24) by appropriate modification of the coupling between an output signal (N) from and and an input signal FSIGNAL(N) to the functional logic (24).

Method and apparatus for ultrafast microwave tissue fixation

Abstract: A method and apparatus for ultrafast microwave tissue fixation using a single mode resonant waveguide constructed with an aperture near one end. The waveguide is also constructed to provide a uniform E field and maximum power field below the aperture. Tissue is placed into a vial filled with fixation solution. The vial and tissue are then inserted through the aperture into the waveguide. Microwave energy is then applied to the tissue which becomes fixated within a short period of time.