Abstract: The present invention is an airborne radar system which scans the flight path of an aircraft with two radar scans, an upper elevation pointing above local level and a lower elevation scan pointing below the glide slope. The radar returns from the upper elevation scan are used to detect the core of the microburst. The core and a model of the windshear which uses the core are used to select angles and range cell candidates, in a lower elevation scan, for hazard detection processing. The candidates in the lower scan, which is pointing at the ground, are used to create a hazard map tested against a predetermined hazard threshold. A threshold violation results in a pilot alert. The hazard map includes a vertical factor determined through model coefficients in the radial outflow as a function of altitude.

Abstract: A segmented stretch waveform for wide band high duty cycle tracking application. The waveform is divided into multiples of two spaced segments as the tracking range closes. Target returns received during spaced segments are combined to correspond to the complete waveform; and range is determined in accordance with the combined waveform. Tracking range can be varied without changing bandwidth, FM slope, duty cycle or processing time.

Abstract: A vanadium oxide compound having the formula VO.sub.2 is disclosed for the purpose of selectively shielding an electromagnetic transmitter or receiver. Vanadium oxide exhibits a marked and rapid transition from dielectric and transparent to electromagnetic radiation to metallic and impervious to such radiation at a specific temperature, 68.degree. C. The compound is preferably mounted as a thin layer on a substrate which has been specifically selected for the desired application. The transmission of radiation is then temperature selected. The preferred method of deposition is an organic hydrolysis reaction.

Abstract: An arrangement of crystal resonators that provides significantly reduced net resonator vibration sensitivity by arranging the crystallographic axes of some of the resonators to have antiparallel relationship, without regard to the acceleration sensitivity vector of any of the crystal resonators.

Abstract: A superconducting microwave selective filter system having a superconducting filter connected to receive RF signals and perform filtering before the RF signals are applied to nonlinear circuitry such as receiver protectors and low noise amplifiers. A single pole n throw point switch selects a desired one of the filters to provide a receiver with a desired frequency, such as an active radar frequency. The low loss and high dynamic range of a superconducting filter permits these filters to be employed in the front end of the system before system nonlinear circuitry.

Abstract: Precise azimuth and elevation angles of arrival of a signal are determined using a rotating interferometer wheel rotatable about an axis parallel to the boresight of the interferometer. The angles of arrival are determined based on the measured phase differences of signals received by the interferometer, corresponding cone angles and the assignment of azimuth and elevation values to the group of conic lines which are nearest each other.

Abstract: The present invention is an integrated millimeter wave (MMW) and an infrared (IR) common aperture sensor employing a common primary reflector for infrared and millimeter wave energy. An active transmitter/receiver millimeter wave horn assembly located at the focus of the primary mirror transmits and receives millimeter wave signals off the primary reflector. A selectively coated dichroic element is located in the path of the millimeter wave energy on the axis between the feed and the primary reflector. The dichroic element reflects infrared energy from the primary reflector to a focal point and at the same time transmits and focuses millimeter wave energy. An optical system relays the infrared energy to a focal plane behind the primary mirror. The dichroic element transmits and focuses millimeter wave energy without significant attenuation such that optical and millimeter wave energy may be employed on a common boresight.

Abstract: Method and apparatus for quickly determining the angle of arrival of a signal at a spinning interferometer based on the phase rate of changes and the cone angles between respective pulses received at the spinning interferometer.

Abstract: The present invention is a radar system that corrects for changes in apparent reflectivity and two-way precipitation attenuation using a correction curve that includes a segment for low rain rates, a segment for high rain rates and, if desired, a transition segment for medium rain rates. The signal to noise ratio is further improved by using a sliding azimuth window during post detection integration processing.

Abstract: A radiator has a planar dielectric substrate which supports a stripline conductor therein. A conductive housing receives and encloses the dielectric and isolates the stripline from adjacent structures. The housing has a radiator with a high impedance termination and the dielectric has a stripline feed with a low impedance open circuit termination. The terminations result in an increased broad band response of the radiator.

Abstract: A precision azimuth angle and .+-. elevation angle of an emitter are determined by measuring the frequency and differential phase .psi..sub.j of a received signal at each of a number of interferometer rotational positions. Each measured differential phase corresponds to a set of possible cone angles satisfying.phi..sub.j,k =cos.sup.-1 (.lambda..psi..sub.j,k /2.pi.S)where .psi..sub.j,k =.psi..sub.j +2.pi.k and .vertline..psi..sub.j,k .vertline..ltoreq.2.pi.S/.lambda.The angular distances or errors between arbitrary azimuth angles or points and each set of cone lines is determined. The point having the smallest error corresponds to the azimuth angle and .+-. elevation angle of the emitter.

Abstract: A multispectral superconductive quantum radiant energy detector and related method utilizing a closed loop of superconductive material having spaced legs, one of which is disposed to ambient. The superconductivity current is divided in the first and second legs according to geometric and kinetic inductances. A ground plane is provided for minimizing the geometric inductance with the loop during injection and removal of the current.

Abstract: An enhanced performance Mode S interrogator that includes a matched channel receiver. The receiver includes equiripple-phase response filters with finite peaks of attenuation. This new class of filters provides a faster rise of attenuation than all-pole filter while extending the equiripple delay further into the stopband.

Abstract: An optical acoustic charge transport (ACT) device provides a variable and continuous delay for RF signals. Received RF signals are converted to light and focused onto an optical ACT device. The continous delay is utilized to generate a false radar return.

Abstract: A multispectural superconductive quantum radiant energy detector and related method utilizing a closed loop of superconductive material having spaced legs, one of which is disposed to ambient. The superconductivity current is divided in the first and second legs according to geometric and kinetic inductances. A ground plane is provided for minimizing the geometric inductance with the loop during injection and removal of the current.

Abstract: Sea clutter can be removed from radar signals by accurately determining sea velocity in a coverage area of a radar scan, updating a median value for the coverage area, and selecting a clutter rejection filter for the coverage area biased on the median value for the coverage area. Preferably, a median sea velocity is stored for each coverage area, as the median value. When processing begins for a coverage area, a previously stored median sea velocity is retrieved and updated. The median sea velocity is updated by converting the median sea velocity into a median phase difference between two echo signals, based upon carrier frequency and the time between receipt of two echo signals, which is preferably more than one interpulse period. The difference in phase between the two echo signals is compared with the median phase difference and the median sea velocity is increased if the median phase difference is smaller and decreased if the median phase difference is larger.

Abstract: A hermetically sealed package for one or more integrated circuit chips that is made of three metal, thick-film layers, and one dielectric, thick-film layer to form a mounting surface for the chip. The first applied metal layer includes the power plane, and the fan-out leads including power and ground leads. The dielectric layer overlays the power plane and includes an annular rectangle overlaying a portion of all the leads of the first layer and an outer boundary strip overlaying extreme ends of the leads. The second screened metallic layer serves as the ground plane, and electrically engages the ground leads of the first metallic layer and the extreme outer ends of the signal leads.

Abstract: A direct frequency synthesizer is provided with a single stage or multiple cascaded stages. Each stage includes a fixed frequency input channel and a selectable frequency input channel which are coupled respectively to the I and L ports of a mixer. The input channel includes a divider having a divisor equal to N. The selectable frequencies range from f.sub.1 to f.sub.1 +j.theta.. Single-pole-multiple-throw switches selectively connect the fixed and selectable frequencies to the mixer to generate output frequency signals through an output filter bank. Specific relationships among N, n and .theta. are used to establish continuous output frequency coverage, stage cascadability and other synthesizer operating features.

Abstract: A dual mode active aperture phased array system for pulsed radar and continuous wave applications. The system may be switched between the two modes without appreciable loss of average effective radiated power. Both the voltage and current of the biasing power to the amplifying transistors is varied to accommodate the difference in peak amplitude power while maintaining the optimum average effective radiated power. The DC power supply is a chopper.

Abstract: A coherent energy transfer system is disclosed which utilizes a doublet pulse laser transmitter in combination with a phase conjugate mirror (PCM) assembly. In one embodiment of the present invention, the first pulse of the doublet pulse signal illuminates the target, whereas the return pulse reflected from the target constitutes a weak signal to be processed using phase conjugate methods. The second pulse of the doublet phase signal activates the PCM assembly and constitutes the energy source used to produce an amplified, phase conjugated beam.