Abstract: The heat sinking substrate herein disclosed is comprised of a core consisting of a rigid graphitic solid in which hexagonal graphite crystallites are bond together by coal tar pitch, the core being enclosed by two metallic face sheets having a coefficient of thermal expansion suited to the electronic packages it supports. The substrate is designed to be installed into a module with a printed wiring board on either side, the module being installed in parallel with other like modules into a chassis. The heat generated by the electronics is input over the face of the substrate and withdrawn by cooling in the walls of the chassis with which the substrates are in good thermal contact. The grain of the core is aligned for maximum thermal conduction along the path to the chassis walls. The substrate is of low weight, has a CTE matched to the supported electronic packages, high thermal conductance, and uses low cost materials.

Abstract: A method for clipping a source polygon to a view window permits the valid (i.e. potentially visible) edges or portions of edges of the source polygon and of the view window boundary edges to be sequentially output for further processing, while determining the valid parts in a predetermined direction around the perimeter of the source polygon, without having to store (other than for a first entry point) the value of exit points from or entry points to the view window. Only an end point of an edge of the source polygon is considered at a time so that a maximum of two intersection point determinations between the source polygon edge and view window boundary planes outside of which the source polygon edge lies are required to ascertain if a portion of the source polygon edge is valid.

Abstract: An electrical power conversion circuit having a readily varied conversion ratio and accommodating bidirectional energy flows is disclosed. The converter employs a series connected and a shunt connected semiconductor switch which may be either unidirectional or bidirectional (depending upon whether AC/DC or DC only operation is sought) and an inductor. The switches are insulated gate voltage controlled devices with charge storing capacity present at the gate. The switches are operated from a variable duty cycle rectangular pulse which is differentiated at the leading and trailing edges to form two pairs of oppositely sensed short duration pulses. The two pairs of short duration pulses are then coupled by a transformer having two matched but oppositely sensed secondaries to the gate circuits of the two semiconductor switches.

Abstract: The invention relates to a variable gain distributed amplifier for use at microwave frequencies, and fabricated in a monolithic microwave integrated circuit format. In the amplifier, the attenuation is varied, based upon digital control of a dual gate segmented FET. The amplifier has a nearly flat insertion phase and amplitude response, and an insertion phase response that varies only slightly between gain settings. The amplifier employs segmented dual gate field effect transistors as the gain elements, having their signal input and signal output electrodes which provide shunt capacities (C.sub.G1S, C.sub.DS) interconnected with serial inductances to form separate low pass transmission lines having relatively high cut-off frequencies. The amplifier has means to insure stability and uses Chebyshef equal ripple techniques to linearize the amplitude and insertion phase response.

Abstract: The output terminals of a three-phase, wye-connected AC source, whose voltage varies over a wide dynamic range, are connected to a pair of DC voltage buses through a pair of oppositely poled, half-wave rectifier networks and a pair of switches. Taps uniformly positioned on the phase windings are brought out through another half-wave rectifier network directly to one bus, and the source neutral is connected directly to the other bus through a diode. A control circuit, operating in response to the DC voltage appearing across the buses, opens and closes the switches to selectively switch the rectifier networks and diode in and out so as to limit the DC voltage to a predetermined, compressed dynamic range.

Abstract: The invention relates to apparatus for epitaxial processing using metal organic molecular beams. The MOMBE apparatus employs a manifold for supplying metal organic vapor to a reactor which is operated under vacuum. The manifold includes a bubbler in which MO vapor is formed and mixed with a carrier gas. The bubbler provides flexible, three parameter control of the MO reagent permitting use with MO reagents of low vapor pressure. A compensation flow is provided parallelling the reagent flow and employing four valves which are ganged and switched so as to supply the MO carrier gas mixture either to the reactor line or to the vent line and maintain equal flows and pressures during this switching operation. The apparatus is capable of forming very thin reproducible epitaxial layers.

Abstract: The invention relates to a digitally controlled variable power amplifier for radio frequency signals. The power amplifier has application to power amplifiers for driving the individual elements of a phased array radar system in which accurate tapering of the power supplied to individual antenna elements is desired for sidelobe control in the face of jamming and other circumstances. In this application, each power amplifier must maintain a stable phase transfer response and should remain at a high power transfer efficiency at each reduced power setting. This performance is achieved by the use of a power transistor of a segmented dual gate design. The segments of the second gate electrode are of digitally scaled widths and are individually energized to activate digitally scaled regions of the transistor. These regions are operated in a saturated class "A" mode in all power settings to achieve the desired stable phase transfer response and high power added efficiency.

Abstract: The invention relates to the distribution of radio frequency signals using optical fibers between a centrally located radar transmitter/receiver and remotely located transmit/receive modules associated with the elements of an active phased array. The invention avoids the need for remotely located lasers, by using the optical carrier generated at the central location for both transmission, when it is modulated by the transmitter and supplied to each T/R module over an optical path; and for reception, when it is supplied to each T/R module unmodulated. An optical switch and an optical modulator in the T/R module permit the antenna return to be converted to an optical format for supply over a second optical path to the central receiver. The arrangement may be further simplified by selecting a simple optical device to perform both the optical switching and optical modulation function in each T/R module.

Abstract: The invention relates to a microstrip to stripline transition which achieves good electrical performance and permits easy, solderless disconnection. The upper portion of the stripline is omitted permitting a flying lead bonded to the microstrip conductor, and which extends across a gap, to be held in contact with the stripline conductor by a removable filler block, which replaces the omitted upper portion of the stripline. The air gap, and the width of the stripline and microstrip conductors adjacent the air gap are dimensioned to form the electrical equivalent of a pi network to achieve a desired response.The filler block is held in place, in one embodiment, by an elongated conductor bridging the upper and lower ground planes of the stripline and which is cut away to form a short waveguide section encircling the transition. The waveguide section is dimensioned to favor only a desired TEM stripline mode and suppress undesired waveguide modes for increased transition efficiency over a desired band.

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: 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: 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 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: 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: 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.