Abstract: The invention relates to compact means for turning power on and off and regulating that power as it is supplied to a pulsed transmitting module in a phased array radar system. The arrangement comprises an operational amplifier, which compares the voltage across the module with a gated programmable digital voltage reference, and a high bandwidth power transistor serially connected with the load, the conductivity of which is controlled to adjust the load voltage to the reference value. Capacitive coupling prevents burnout of the transmitting module from a sustained "on" signal and a capacitive feedback connection at the operational amplifier limits the rise time of the voltage supplied to the load to avoid ringing. The use of a "switch" in a regulating mode reduces the amount of local storage capacity required to achieve comparable regulation, and leads to a power conditioner for an individual transmitting module, which is both compact and of high performance.

Abstract: A location dependent signal processor for radiant energy detector arrays which include two-dimensional spatial filtering and/or background normalizing, with means providing programmed control of the signal processor filter weighting and normalizer thresholding operations as a function of the location of each successive output pixel with respect to the periphery of the detector array, so as to enable the signal processor to minimize the effects of initialization and wrap-around pixels on the processor signal output.

Abstract: A phase shifting network with multiple outputs between which a constant phase difference is maintained over a large frequency range. The configuration consists of a four branch all pass network which in turn consists of four similar all pass networks one in each branch. An in phase and an out of phase input signal are applied to this network and four signals in phase quadrature, 0.degree., 90.degree., 180.degree., and 270.degree. may be obtained from the network. The network is designed for operation at frequencies of micro and millimeter wavelengths and may be realized from resistive and capacitive elements fabricated upon a common monolithic substrate. A suitable substrate is gallium arsenide, permitting both passive and active elements to be formed and interconnected by lithographic techniques.

Abstract: An improvement for the real-time computer generation of visual scenes based on an algorithm that reduces the processing of elevation data to simple repetitive accumulations and a compare operation to generate occult data using grid elevation data bases is disclosed. The improvement reduces the size of the on-line, high speed, random access, data base memory required in image generation from grid data bases and reduces image generation time. The grid data base is divided into an array of data blocks. The data blocks are sequentially transferred to on-line ping-pong buffer memories (14), and each data block is processed through to final display by a view ray processor (16). The order of block selection is such that the sweep data remains continuous. When a sweep leaves a block, exit processing parameters are stored in a sweep horizon memory (18) as sweep parameters.

Abstract: The invention relates to a voltage controlled analog phase shifter for operation at millimeter and microwave wavelengths using MMIC (Monolithic Microwave Integrated circuit) fabrication techniques. The phase shifter is formed of an artificial transmission line consisting of multiple unit elements in which each unit element contains a serial transmission line-inductance and a shunt diode capacitance which is variable as a function of an applied potential. In the design, the interconnecting transmission lines may be a small fraction of a wavelength, substantially less than one-quarter wavelength, and of high impedance relative to the characteristic impedance of the phase shifter. In consequence of the lumped design, each unit element, and a phase shifter using a plurality of such unit elements may be very small. The design also exhibits a low to negligible power consumption.

Abstract: A microstrip fed printed dipole with an integral balun is disclosed, fabricated upon a planar dielectric substrate by patterning metallizations disposed on the two surfaces of the substrate. In the arrangement, the ground plane of the unbalanced microstrip transmission line is bifurcated by a central slot to form a balanced transmission line coextensive with the slot which becomes a part of the arms of the dipole and which at the same time serves as the ground plane of a continuation of the microstrip feed. A continuation of the strip conductor of the unbalanced microstrip feed having a "J" shaped configuration continues over the bifurcated ground planes and crosses the slot in proximity to the dipole for effecting an efficient unbalanced feed to the balanced dipole. The arrangement has a double tuned characteristic with two available and independent adjustments facilitating reproducable, optimized broadband performance.

Abstract: An improvement for the real-time computer generation of visual scenes based on an algorithm that reduces the processing of elevation data to simple repetitive accumulations and a compare operation to generate occult data using grid elevation data bases is disclosed. The improvement adds three dimensional texture to close approach scenes to provide visual cues to the observer. The texture data is derived from the grid elevation data base itself and includes delta elevation and delta color values. The delta elevation values are added to the interpolated elevations computed by the image generator and the delta color values modulate the interpolated colors computed by the image generator. Since the texture data base is derived from the grid data base itself, the texture data base is already on-line thereby simplifying the memory and computational requirements of the computer image generator.

Abstract: The invention relates to a transition between stripline transmission lines that is efficient at microwave frequencies and readily fabricated, and which may be used to achieve cross-overs in stipline circuits.The transition includes a coaxial section placed between pads at the ends of the stripline conductors. The coaxial section is formed by a resilient center conductor surrounded by an incomplete circle of pins connected to the ground planes and forming the outer conductor. The connections to the pads enter the ends of the coaxial section at the azimuth of the gap in the circle of pins. Good high frequency performance despite the discontinuity between the pads and coaxial center conductor is achieved by increasing the characteristic impedance of the coaxial section and that of the stripline near the transition relative to the characteristic impedance of the stripline remote from the transition.

Abstract: The invention relates to a metal matrix composite used to support and/or enclose discrete electronic semiconductor devices, monolithic integrated circuits, hybrid circuits, and multi-layer printed wiring boards. The matrices herein disclosed employ aluminum as the matrix with Beta Eucryptite as the additive in a volume percent of up to 60. The preferred range of from 55 to 45 percent by volume of the additive has a coefficient of thermal expansion matching the common semiconductor materials and common ceramics used for electronic enclosures. The composite uses low cost materials, and due to the affinity of the additive to aluminum is easily prepared. The resulting structures have good thermal conductivity and low weight.

Abstract: The invention relates to the distribution of power and control commands to a plurality of pulsed T/R modules coupled to the antenna elements of a phased array radar and arranged in rows and columns. The novel power distribution system includes a large number of small capacitors, at least one per module, a lesser number of large capacitors, at least one at each end of each row, and bus bars dimensioned for a very small r.f. impedance for supplying peak power in a timely manner to the modules from the large capacitors. Each row has four large (1KW) dc power supplies for providing the average power. The power conditioning elements within the modules are of reduced bulk while achieving "droop" free operation. The control commands are carried by lower current capacity runs on a layer laminated to the bus bar.Connectors attached to the laminated bus bar and indexed at the module positions provide high power and control commands.

Abstract: The invention relates to a matching network which may be serially inserted in the path between a transmitter power amplifier and/or a receiver low noise amplifier and an element of a steerable array antenna to compensate for mismatching occurring when the antenna is steered away from bore sight or tuned to off resonant frequencies. The invention permits computer controlled digital setting of the matching network in accordance with the known impedance characteristics of the antenna element, to restore VSWRs which in an exemplary case may have a maximum design value of 3.0 when uncompensated to a VSWR of 1.6 with a simple matching network, or to a VSWR of 1.22 with a more highly corrected matching network.

Abstract: An improved element for use in an electrically steered antenna array is disclosed comprising a dipole, an integral balun and a 180.degree. phase shift bit. The arrangement utilizes printed circuit techniques throughout using an unbalanced microstrip for connection to electrical circuitry, a balun for transitioning from unbalanced microstrip to a balanced dipole antenna and includes a low loss 180.degree. phase shift bit formed by the use of a branched feed network including two diodes whose conductive states determine the sense of antenna excitation, and produce the equivalent of a 180.degree. phase shift bit.

Abstract: The invention relates to a high performance optical system for a wide angle IR imager requiring a cryogenic environment for the IR detector array. The wide angle requirement makes it necessary for one lens to be behind a "cold aperture" within the cryogenic environment where focusing is difficult and performance of the aperture reduced. These objectives are minimized by use of a telecentric lens pair, one member of which is within the cryogenic environment. The telecentric lens pair refocuses the primary image formed by an objective lens, permitting a high quality image to be formed on the IR detector array. The usual errors in positioning the internal lens, which might impair the quality of the focused image, are avoided by a compensatory repositioning of the externally accessible objective lens.

Abstract: A protective shield for an electrically steered, high performance C Band antenna array is disclosed. The shield is of a multi-layer construction in which a sandwich is formed between two fiberglass layers and a central foam core to minimize electrical reflections; and in which an additional foam layer is provided for structural support and to minimize changes in mutual coupling, installed between the sandwich and planarly disposed dipoles of the array. In addition, a teflon layer is applied to the outer layer of the sandwich and coated with fumed SiO.sub.2. The hydrophobic properties of the teflon-fumed SiO.sub.2 combination minimizes the effects of rain on antenna performance.

Abstract: The invention relates to a low noise amplifier for use at microwave frequencies which may be fabricated using integrated circuit techniques. In accordance with the invention, critical components are made adjustable so as to simplify the design process and manufacturability of the amplifier. A two stage low noise amplifier is disclosed in which TEE networks are used as input and output networks in each stage, and in which one element of each TEE includes an adjustable spiral inductor. The value of each adjustable spiral inductor may be adjusted by removal of one or more air bridges disposed along the inner turn of the inductor. This permits one to "tune" the amplifier and optimize its performance.

Abstract: A point source spatial filter determines the quality of a central point source or pixel under test to thereby detect point sources and minimize the signals from all sources other than the desired point source. The spatial filter incorporates a buffer apparatus for receiving pixel signals, memory apparatus for storing pixel data for the test pixel and surrounding pixels, comparator apparatus for comparing test pixel values against a given number of surrounding pixel values to determine if the test pixel is a local maximum or minimum value, subtraction apparatus for subtracting the value of the nearest-valued surrounding pixel from the test pixel value when the test pixel is determined to be a local maximum or minimum, and apparatus for indicating the difference between the value of the test pixel and that of the surrounding pixel of closest value.

Abstract: A novel readout circuit for a charge injection device is disclosed permitting selection of the integration time to optimize performance. A primary application of the invention is to IR sensing in which performance is required at both low and very high levels of radiation. The readout circuit, in one practical configuration, utilizes a dump pulse recurring at the interval required to scan all elements, in advance of the read pulse also recurring at the scanning interval. The integration time may be adjusted in multiples of the readout period for a single element up to the frame scanning interval, or in approximate fractions of the readout period for a single element, or, at the limit, in a fraction of a microsecond.

Abstract: A novel signal scaling MESFET of a segmented dual gate design is disclosed. The MESFET, which is monolithically integrated on a semi-insulating substrate capable of localized surface modification to form active semiconductor regions using MMIC (monolithic microwave integrated circuit) techniques, has a small AC signal transfer which is adjustable in selected discrete steps. For operation in the gigahertz range, the substrate is preferably of gallium arsenide.In applying the MMIC technique, the MESFET, including segment electrodes and segment interconnections, and the electrical connections, signal paths, and passive components connected to the MESFET are formed on the substrate and defined by a photolithographic process. The technique permits reproducable feature definition and very compact minimum reactance segment interconnections, reducing deleterious parasitics and facilitating virtual unitary MESFET operation to very high frequencies.

Abstract: A readout circuit for IR sensing charge injection devices (CID) is disclosed, the CID comprising a two-dimensional array of dual-gate sensing sites on an InSb or HgCdTe substrate. The novel readout circuit, which operates in the charge sharing mode (CSM) in extracting image information, is modified to correct for the subtractive effect present when the CSM mode is used. The readout circuit includes a plurality of processors, one for each column, from which a single serial output may be obtained by a demultiplexer, and into which signals derived from successive pixel sites on the associated column are coupled. A first quantity representing the subtractive error is obtained without injection from each column line by double sampling during a first interval. A second quantity representing the signal corrected for subtractive error is obtained with injection from a pixel site by double sampling during a second interval, the samples being increased by the error quantity.

Abstract: The invention relates to a charge injection device for optical sensing including a novel readout circuit facilitating an extended dynamic range. The invention has primary application to linear arrays for IR sensing.Sensitive, low-level operation is achieved in a primary readout means by allowing the charge to accumulate in the potential well of the individual sensor elements over the line period with each element being reset at the pixel readout rate and by using a charge injection pulse to clear stored charge from the individual sensor elements. A secondary readout means is also provided in which the charge is allowed to accumulate over a period not exceeding the pixel readout interval for unsaturated large signal operation and by sensing the change in depth of the potential well. The two readout means are combined in the eventual display to provide an improvement of typically three orders of magnitude in the dynamic range of the CID.