Abstract: A ring laser gyro uses means for shaping the gas flow, which inevitably develops as a result of a DC discharge, to optimize the effect of the Fresnel-Fizeau drag on the output signal of the gyro. In one embodiment, a sufficient component of the gain medium flow is provided to produce a substantially constant Fresnel-Fizeau component of the output signal even in the presence of variations of the discharge current. In another embodiment, a sufficient component of gain medium flow is provided to substantially eliminate the Fresnel-Fizeau component of the output signal at a predetermined level of discharge current.

Abstract: A ring laser gyro uses a nonplanar path having at least one plane of mirror symmetry and two pathlength control mirrors in order to reduce scatter variations occurring during the operation of the laser gyro. The mirrors used to produce such path are fixed to an isotropic supporting block having passages therein that define the path segments and the mirrors are moved out or in by the expansion or contraction of the block. The two pathlength control mirrors are disposed diagonally opposite each other on the plane of mirror symmetry, and are placed on substrates whose positions are controllable, each substrate being coupled to means for controlling the positions of the substrates as a function of the pathlength. With such a mirror configuration, the pathlength may be held constant by a suitable control means and the relative movement of the mirrors constrains movement, with respect to the mirrors, of the beams circulating in the path to directions perpendicular to the planes of incidence on the mirrors.

Abstract: A lightweight patch radiator phased array antenna having a single layer patch construction on an artificial dielectric, such as syntactic foam, which achieves a factor-of-ten weight savings over an array constructed with conventional materials. An additional sixty-five percent weight reduction is achieved by cutting away the dielectric material down to the array antenna's ground plane everywhere except under the patch radiator. This construction allows placement of a thermal control material over the patch and ground plane for space applications.

Abstract: A microwave power combiner includes a first plate having disposed in a first surface thereof a first plurality of grooves and a second plate having disposed in a first surface of said second plate a second plurality of grooves, with said second plate being mated to said first plate and with said first plurality of grooves in the first plate disposed in alignment with the second plurality of grooves in the second plate to provide a plurality of waveguide regions. The waveguide regions are further disposed to provide a plurality of hybrid Ts preferably matched hybrid Ts or magic Ts which are selectively interconnected to form an integrated combiner structure. A first surface of the plate is used to mount a plurality of IMPATT diode modules whereas the second opposite surface of the composite plate is used to mount a heat sink thereby providing a thermal path between the diode modules through the composite plates to the heat sink.

Abstract: A transmit/receive (T/R) module of an electrically steered phased array antenna having a receiver comprising a T/R switch, an impedance matching and bias feed network, and a low noise amplifier. The T/R switch comprises a .pi. network to provide a matched termination for protecting the receiver in the transmit mode. This .pi. network emulates a one-eighth wavelength transmission line by providing a 45 degree phase delay, but it exhibits the isolation and bandwidth characteristics of a one-quarter wavelength line. The T/R switch effectively isolates the low noise amplifier from an antenna during transmit mode and uses less than half the area on a substrate typically required for a conventional one-quarter wavelength transmission line. In a receive mode the T/R switch has minimal effect on an RF input signal passing through it.

Abstract: A low array antenna having transmit/receive (T/R) modules, which contain a digitally-controlled variable attenuator, for each of the two polarizations (horizontal and vertical). The array has a cylindrically curved surface which closely conforms to the shape of the fuselage of an airborne vehicle or another structure. Each polarization feeds into an elevation beamformer apparatus which provides both a uniform taper and a Bayliss/Taylor taper. As the beam is scanned in elevation, the amplitude taper is adjusted via the variable attenuator to control the taper of a sum pattern and thereby achieve low sidelobe far field sum patterns. The same attenuators that are used for the sum pattern also feed a difference network. The T/R module attenuators are set to yield the desired low sidelobe sum illumination for a desired elevation scan angle.

Abstract: A cryogenic signal coupling apparatus includes a laser which launches optical power into an integrated optical waveguide (IOW) within a cryogenic region via an imaging lens. This optical power is then equally split by a passive optical splitter, and fed to one or more 1.times.2 IOW devices. Within the cryogenic region, a plurality of infrared sensing photodiodes provide electrical signal outputs in response to optical stimuli, which signal outputs are amplified and selected by a multiplexing arrangement for application as the modulating signal to one of the 1.times.2 IOW's. Control electronics also within the cryogenic region supply timing and control information to the other electronics therein. The IOW's modulate their input optical power in accordance with their respective modulating electrical input signals, and provide differential optical outputs which are directed across the thermal barrier to individual differential optical receivers.

Abstract: An impedance matching and bias feed network for interfacing to a low noise amplifier of a receiver section of an electrically steered phased array antenna. The impedance matching and bias feed network includes an inductor and capacitor network for impedance transformation while providing in shunt with a 50 ohm input side of the network a gate bias path via the inductor to the low noise amplifier thereby substantially reducing the receiver noise figure.

Abstract: An efficient power MOSFET resonant gate drive circuit having a large coupled inductor between and in series with two switching transistors. The inductor prevents cross-conduction from the power bus through the drive transistors as may be caused by simultaneous turn-on due either to switching delays or single-event-upset-radiation from energetic cosmic rays. In either case, the inductor presents a high impedance for current that tries to flow through both transistors simultaneously. A center tap on the inductor is connected to the gate of the power MOSFET. An equivalent inductance resonates with the equivalent capacitance of the gate of the power MOSFET providing fast turn-on of the power MOSFET. During turn-off of the power MOSFET, one drive transistor is switched-off and the other drive transistor is switched-on.

Abstract: An apparatus is disclosed for controlling the brightness of a matrix-addressed flat panel CRT display of a type having intersecting column and row conductors forming, respectively, the gate and cathode electrodes of a field electron emission array. The brightness control is effected by controlling the voltages applied to the drive lines of the intersecting conductors. A waveform having progressively increasing voltage steps is sequentially applied to the row conductors. The voltages at each of the steps are preferably selected to enable electron beam currents which provide brightness levels which are twice the brightness of the previous step. Binary-coded brightness control signals are simultaneously applied to all of the column conductors. The voltages of the stepped waveform and the binary-coded signals comprise a combination of video information data and correction data which compensate for irregularities in the current emitting structure at the selected conductors.

Abstract: A radar performance monitor (RPM) receives a transmitted radar signal from a radar system being monitored and couples the signal to a recirculating loop comprising a SAW delay line in order to produce a series of simulated radar return signals of equal amplitude and by using the same frequency as the received radar signal providing the frequency falls within a predetermined bandwidth of the SAW delay line. The simulated radar return signals are displayed at the radar system and used to evaluate the operation and calibration of a transmitter and the sensitivity and calibration of a transmitter and the sensitivity and calibration of a receiver in the radar system. The radar performance monitor is actuated at the option of a radar operator.

Abstract: An optical beam steering device for use in a single-aperture laser transceiver system provides deflection of the transmitted and received beams in two planes, while maintaining the distinctive identities of each channel respective to their polarizations. The invention utilizes four single-dimensional beam deflecting devices, two for each orthogonal linear polarization of the two transceiver channels, one of these for each steering axis. In addition, a 90.degree. polarization rotator and a quarter-wave plate are included in the arrangement of beam deflecting devices to satisfy the polarization requirements of these devices and of the transceiver channels.

Abstract: A cryogenic signal coupling apparatus includes a laser which launches optical power into an integrated optical waveguide (IOW) within a cryogenic region via an imaging lens. This optical power is then equally split by a passive optical splitter, and fed to one or more 1.times.2 IOW devices. Within the cryogenic region, a plurality of infrared sensing photodiodes provide electrical signal outputs in response to optical stimuli, which signal outputs are amplified and selected by a multiplexing arrangement for application as the modulating signal to one of the 1.times.2 IOW's. Control electronics also within the cryogenic region supply timing and control information to the other electronics therein. The IOW's modulate their input optical power in accordance with their respective modulating electrical input signals, and provide differential optical outputs which are directed across the thermal barrier to individual differential optical receivers.

Abstract: A microwave power combiner includes a first plate having disposed in a first surface thereof a first plurality of grooves and a second plate having disposed in a first surface of said second plate a second plurality of grooves, with said second plate being mated to said first plate and with said first plurality of grooves in the first plate disposed in alignment with the second plurality of grooves in the second plate to provide a plurality of waveguide regions. The waveguide regions are further disposed to provide a plurality of hybrid Ts preferably matched hybrid Ts or magic Ts which are selectively interconnected to form an integrated combiner structure. A first surface of the plate is used to mount a plurality of IMPATT diode modules whereas the second opposite surface of the composite plate is used to mount a heat sink thereby providing a thermal path between the diode modules through the composite plates to the heat sink.

Abstract: An error detection and correction apparatus and method in a memory system for performing single symbol error correction and at least double symbol error detection of data errors and single symbol error detection and at least double symbol error detection of addressing errors using a modified Reed Solomon code. A first of three parity symbols in a codeword is used to determine the value of a single symbol error, if any, over a memory word comprising data symbols and its corresponding address comprising address symbols. A second parity symbol is used to locate a single symbol error, and a third parity symbol is used to detect at least two errors in the data and address symbols. The three parity symbols are used to generate syndromes which determine if there is an error and what corrective action to take.

Abstract: A radar type center fed antenna comprising a small radiating horn supported at the focal point of a parabolic reflector by three struts which are oriented to minimize the parallel polarization scattering and which have a low scattering ogive cross-section. The horn is mounted at the vertex of the parabolic surface and the intersection of the three struts using a bracket that provides minimal blockage. The struts are attached to the perimeter of the reflector. One strut having a feed waveguide is attached to the top-center of the reflector and the other two are attached at points on either side of the bottom-center at thirty degree angles to the vertical plane. The strut shape and feed-horn supporting and attaching arrangement and the integration of the feed waveguide into one of the struts results in a very low sidelobe antenna that produces a far-field pattern that has very low forward scattering due to feed and strut blockage.

Abstract: A threshold level generator for generating threshold levels to detect zero-crossings of a spread spectrum received waveform. An IF sampler quantizes the received spread spectrum signals at IF. The IF signal is sampled at a number of quarter cycle intervals to allow sampling in sequence of the in-phase (I) and quadrature-phase (Q) components. The outputs of the IF sampler are two bits, a sign bit and a magnitude bit. The threshold level generator using only the sign bit of the I and Q samples sets a threshold level (T0) to detect the zero-crossings of a received waveform. Two magnitude threshold levels are set at fixed offsets (D1 and D2) from the T0 threshold level.

Abstract: A laser radar system for measuring wind velocities including apparatus for permitting the system to measure the direction of the atmospheric flow field. A modulator is used to chirp the laser frequency toward increasing frequencies. The local oscillator frequency available for homodyning will be offset from the initial transmitted frequency by an amount equal to the chirp rate multiplied by the round trip transit time to the aerosols at the focal point of the converging laser beam. During the up-ramped chirps of the optical beam frequency, the Doppler shift frequency of aerosols moving toward the laser beam will be translated to a lower frequency, and the Doppler shift frequency of aerosols moving away from the laser beam will be frequency translated upward.

Abstract: A multibeam phased array radar includes identical N:1 equal-split combiners and overlay hybrid couplers which form multiple tapered and weighted beams. The radar is configured with a single transmit/receive (T/R) module for each antenna element. The T/R modules contain a high power amplifier for transmit, low noise amplifier for receive, phase shifter for beam steering and attenuator for overall weighting. Each T/R module is connected to an unequal-split coupler which divides the received signal into signals of different amplitudes. Each of these signals are fed into a separate N:1 equal-split combiner, thereby forming separate beams. The illumination taper of each beam is determined by the coupling values of the couplers and the setting of the T/R module attenuator. There is disclosed a first embodiment including two beamformers and a second embodiment extending the concept to more than two beamformers.

Abstract: An integrated DC/RF stripline flexprint module edge connector comprises a stripline RF transmission line that operates at microwave frequencies. The connector mates and clamps DC and signal conductors in a flat flexible circuit and an RF conductor located in an RF signal stripline with a matching pattern of conductors on an edge of a module mating plug. The Rf conductor is sandwiched between two equally spaced ground planes and forms a lapjoint connection with the mating plug. The engagement of the connector to the edge of the mating plug is accomplished by a zero inserting force clamp. The clamp secures the connector comprising the DC and signal conductors and the more rigid RF signal stripline adjacent to the flexprint.