Abstract: A method and apparatus for forming plasma sheets of preselected planar curvature, which can be used as mirrors for X-Band microwaves and above. A plasma is created using a shaped cathode. Confining magnetic fields maintains the plasma in the shape of the cathode. Additional magnetic fields can provide additional curvature to the plasma sheet.

Abstract: A method and apparatus for reducing the calculations necessary to track a mber of targets. The invention trades off the magnitude of search radius in parameter space against the number of extra copies made of the track data structure in a manner that inherently saves computation as the number of targets becomes large.

Abstract: A new system and technique for cancelling interference in frequency agile ceiving systems. Main and auxiliary signals are supplied to a pair of multiple loop side-lobe cancellers which are capable of being tuned to different frequencies. At the same time, under the control of a timing clock, plural frequencies are selected and multiplexed between two channels at the time of a radar pulse transmission. The side-lobe cancellers and radar are coupled to the channels such that each caneller operates at a given frequency for two consecutive pulse periods, with the radar transmitting at said given frequency during the second pulse period. By continuously cycling between the two channels, each canceller is operating at the proper frequency to cancel interference even though the radar is changeing frequency on a pulse to pulse basis.

Abstract: A detector beamformer array system having a sparse array and a reference ay. The reference array is adapted, according to known principles, to have an output response with one main lobe significantly larger than all other side lobes, and with a substantially flat response. Signals received by both arrays are cross-correlated with one another, and only signals sufficiently correlated are annunciated. The resulting adaptive array system has a resolution even better than that of the sparse array's aperture, and with directional sector selectivity corresponding to the angular width of the reference array's mainlobe, providing a system having high resolution and directional selectivity, but with far fewer sensors than with filled arrays used for this purpose.

Abstract: A method and apparatus for generating a track data set corresponding to a plurality of objects. A system employing the invention receives reports, e.g. radar echoes, from the plurality of objects over a time interval, partitions the time interval into subintervals or time bins, and sorts the returns into the time bins. In each bin, the reports are very close to one another in time, so that, in correlating the reports in each bin to the tracks, one can use the reports to form the necessary search tree, rather than using the tracks. Doing so increases efficiency if the number of reports per time interval significantly exceeds the number of tracks.

Abstract: A klystron amplifier in which the drift tube is in the form of a casing and a central member disposed coaxially about the same centerline to form a coaxial space between the central member and the casing which runs parallel to the centerline, and through which the klystron's electron beam flows. The casing and central member are maintained at ground potential, which maintains the space charge of the electron beam at a low level, permitting the klystron to operate more efficiently and output higher power.

Abstract: An apparatus and method for detecting acoustic signals originating in a brain, such as those that characterize intersaccular aneursyms. The apparatus has a piezoelectric detector mounted with a cupping receptacle, the receptacle formed to receive an acoustic matching medium and press the medium against the eye socket of a patient. In this manner, the apparatus provides an acoustic path between the brain and the detector that is inherently low loss and acoustically matched, making for a system that is inherently sensitive. In particular embodiments, the cupping structure can be goggles which can be mounted on the patient's head for convenience, or can be of a form enabling a technician to press the structure against the eye socket.

Abstract: In an interferometer apparatus used for monitoring an object surface, the apparatus having a source of coherent light, a beam splitter for dividing the coherent light into a reference beam and an object beam, another beam splitter for dividing the object beam into two separate portions, and a light detector for detecting light interference, comprising an externally-pumped phase-conjugate mirror working in conjunction with a self-pumped phase-conjugate mirror. The externally-pumped phase-conjugate mirror receives the reference beam, receives one portion of the object beam, and reflects the received portion of the object beam to the detector as a first phase-conjugate beam. The self-pumped phase-conjugate mirror receives a second portion of the object beam and reflects the received portion of the object beam to the detector as a second phase-conjugate beam.

Abstract: A neural net, and method of using the net, to solve ill-posed problems, such as deconvolution in the presence of noise. The net is of the Tank-Hopfield kind, in which input to the signal net is a cross entropy regularizer.

Abstract: Method and apparatus for improving detection ranges of a pulsed radar sys wherein electromagnetic return signal data in range cell order is doppler filtered, digitized and stored in doppler memory channels over multiple scans of an azimuth. The digital doppler data in each doppler memory channel is scan-to-scan integrated over a predetermined number of scans to produce target displays for each possible velocity. The target displays are stored in a velocity memory, which is partitioned into velocity channels, each velocity channel corresponding to one possible velocity. A selector selects the target display having the largest total magnitude as a display signal. The scan-to-scan integrated target displays are not subject to collapsing losses since only target signals plus noise signals will be stored in the doppler memory channel corresponding to the target's velocity.

Abstract: A photoconductive semiconductor device having a source, a drain, and a photosensitive channel therebetween. The channel has a surface layer that is highly doped with respect to the remainder of the channel, compensating at least in part for the channel's surface depletion layer. In this manner, the photosensitivity of the device is increased without disproportionately increasing wasted dark current. In a preferred embodiment, the additional doping of the channel's surface layer is done by ion implantation, and the device is a monolith formed of gallium arsenide.

Abstract: A multiport microwave multiplexer having components which are log-periodically scaled structures is shown and described. Circuit parameter values and characteristic frequencies are determined and a first output port is linked by a constant ratio to corresponding quantities that define the response of other networks. A capacitively end-coupled channelizer filter is used for each channel of the multiplexer.

Abstract: A buried-heterostructure laser modulator for modulating a laser beam includes two adjacent thin epitaxial first layers of oppositely doped semi-conductor material and a thin epitaxial buried layer of undoped semi-conductor material located between the two adjacent first layers. The buried layer forms a single mode optical channel having a width larger than a height thereof with the width equal to or greater than a width of a diffraction limited waveguide mode of the laser beam. Two thin epitaxial second layers of similarly and heavily doped semiconductor material are provided respectively adjacent the respective first layers of the same doping. One of these second layers is provided on a side of a semi-insulating substrate and two strip lines of opposite bias are provided on the side of the substrate and connect to a respective second layer of the same bias. The two adjacent first layers are preferably AlGaAs and the buried layer is preferably GaAs with a width less than about 1.

Abstract: A bi-directional optical transmission system for radio frequency electrical nergy includes first and second transmitter/receiver stations which transmit and receive light signals along an optical path therebetween. Each station includes a laser transmitter for transmitting a carrier light beam which is intensity modulated by a synchronization of an input radio frequency electrical signal. A photodetector at each station detects the intensity variations of the carrier light beam from the other station and outputs a respective radio frequency electrical signal which is synchronized with the radio frequency electrical input signal of the other station. A beam splitter is provided between the optical path at both the laser transmitter and photodetector to split the light beams incident thereon into a pass portion and angularly reflected portion. An isolator device also is provided between the laser transmitter and beam splitter to isolate the laser transmitter from back reflections.

Abstract: A semiconductor heterostructure useful as a photodetector in the far infrared. The barrier layers of the heterostructure are doped os that charge carriers migrate from the energy bands of the barrier layers towards the energy bands of the quantum wells, but remain weakly bound to the doping impurities in the barrier layers. Because of weak residual bonding, the energy necessary to raise these electrons fully into the quantum wells' energy band is significantly reduced, extending the lower frequency range at which such devices are useful as photodetectors. Selection of several of the heterostructure's dimensions determine the impurities' resonant absorption frequency, and application of an electric or magnetic field shifts the well's resonant absorption frequency, in effect frequency fine tuning the heterostructure.

Abstract: A method for fabricating field emitter arrays is disclosed which uses a substrate as both an emitter tip mold and an insulating layer. A thick single crystal substrate is orientation-dependent-etched on one side to form a plurality of holes having crystallographically sharp apices or a non-crystalline substrate is etched on one side to form a plurality of holes with a high depth-to-width ratio. An emitter layer is deposited on the substrate surface and in the plurality of holes. The remainder of the field emitter array structure is then formed on the opposite side of the substrate using conventional deposition and etching techniques. Once the emitter is formed, the remaining fabrication steps are self-aligning. The field emitter array thus formed exhibits high input impedance at high frequency, making the field emitter array suitable for high frequency uses.

Abstract: A radar ECCM system for degrading the effect that a standoff noise jammer has on a radar receiving site that is tracking an incoming aerial target. The system effectively removes from the mainlobe of the beam emanating from the site the component of random noise contained in the jamming signal.

Abstract: A millimeter wave Cassegrain antenna for a seeker missile wherein a sub-reflector has two side portions which can be masked in order to widen the antenna's azimuth beam width without widening the elevation pattern. The side portions of the sub-reflector are masked by a radar absorbing material which is disposed in a masking position as the missile approaches its target.

Abstract: Methods for accurately measuring the range between two platforms with relative motion between them using a stable clock located on each platform. A series of pulses are sent from one platform to the other at times known to each platform by prearrangement, the arrival times measured, and statistical methods used to calculate a correction from the clocks to bring them into greater synchronization, thus allowing highly accurate determination of the range between the two platforms.

Abstract: A method and means for x-ray lithography which utilizes means for producing in a vacuum system a high-temperature plasma from which soft x-rays are emitted. The x-rays pass through a mask exposing an x-ray resist on a substrate to produce the desired pattern on the substrate. The x-ray spectrum has a significant energy in the 1-5 keV range. These x-rays pass through the support layer of the mask, stop in the pattern material (gold) of the mask or, where the pattern material is lacking, are absorbed adequately by the x-ray resist. Since there is very little energy above 5 keV, there is little if any substrate damage due to the x-rays.