Abstract: A Doppler radar apparatus includes a first oscillator for generating a first sweep signal to repeatedly sweep a predetermined frequency range periodically; a second oscillator for generating a second sweep signal having sweep properties identical to those of the first sweep signal, the second oscillator 41b starting sweep before the first oscillator finishes frequency sweep; a power combiner for combining the first and second sweep signals to generate a transmission signal; a switch for receiving, as inputs, the first and second sweep signals, and switching an output between the first and second sweep signals synchronously with the timing when sweep with each of the first and second sweep signals is terminated; and a mixer for mixing a reception signal coming from a part of the transmission signal reflected in a target and received, and an output signal from the switch with each other to produce an output signal from the mixer.

Abstract: A solid state active aperture high power polarization agile transmitter, either single or dual polarization, employing nonreciprocal antenna elements, designed such that it can be used in an Electronic Warfare system that is more efficient and less expensive. Antenna beam steering is accomplished with variable phase shifters that are used to set the RF signal phase of each element. The beam steering function is implemented with a hardware architecture where the phase shifters are built-in ahead of the power amplifiers such that these low power phase shifters impart phase delays to low power signals without wasting RF signal power and hence improving efficiency. These power transmitter devices are also more reliable, lighter in weight and smaller in size.

Abstract: Methods and systems for determining the direction to a transponder are disclosed. The methods and systems include transmitting a first signal to an area where communications with a transponder is desired; producing a second signal desired from the first signal; receiving the second signal via a first and second antenna forming a difference signal from the second signal received via the first and second antennas; forming a third signal by adding the second signal received via the first antenna and the second signal received via the third antenna; delaying the difference signal; and comparing a fist polarity of the delayed difference signal with a second polarity of the third signal.

Abstract: Apparatus for the identification of articles (5) endowed with device for changing the polarization properties of the radiation, comprising a source (1) of non-randomly polarized microwave radiation, and a detector (3) for detecting the change in polarization properties of the radiation. The microwave radiation may have a first plane of polarization and, in use, the device for changing the plane of polarization properties of radiation may change the first plane of polarization to a second plane of polarization. The detector (3) for detecting the change in polarization properties of radiation may comprise a receiving antenna (4c) connected to suitable microwave detector (3), where the receiving antenna (4c) is arranged to favour reception of radiation having the second plane of polarization. For example, the transmitting (4b) and receiving (4c) antennas may be waveguide antennas.

Abstract: An adaptive cross polarization electronic countermeasures system comprising identical transmit and receive antennas. The transmit antenna is rotated 180 degrees with respect to the receive antenna. The transmit and receive antennas are mounted facing the same direction allowing for reception of an incoming RF signal from a monopulse radar and transmission of the signal back to the monopulse once ECM jamming is applied. The incoming RF signal is separated into vertical and horizontal components by coupling to vertical and horizontal feeds within the receive antenna. Each component is then amplified sequentially through the system and transmitted back to the monopulse radar. At the transmit antenna, the vertical component is transmitted out of the horizontal feed of the transmit antenna 180 degrees out of phase with respect to the feed. The horizontal component is transmitted out of the vertical feed of the transmit antenna with no phase shift.

Abstract: A device for the unambiguous measurement of the angle of roll of a projectile, comprises at least a radar equipped with means of processing and sending a signal to the casing of the projectile in at least one direction of incident polarization; a set of parallel grooves made on the casing, the depth of which is modulated dissymmetrically with respect to the axis of symmetry of the projectile; the axis of symmetry of the projectile not passing through the point of the antenna of the radar where the antenna beam is generated, the processing means analyzing, in reception, a signal back-scattered by the casing of the projectile, the signal being modulated as a function of the angle of roll of the projectile, the modulation having two maximum local values corresponding to two angular roll positions of the projectile such that the polarization {overscore (E)} is parallel to the grooves, the processing means removing the 180° ambiguity by comparing the levels of the local maximum values.

Abstract: Methods and systems for determining the direction to a transponder are disclosed. The methods and systems include transmitting a first signal to an area where communications with a transponder is desired; producing a second signal desired from the first signal; receiving the second signal via a first and second antenna forming a difference signal from the second signal received via the first and second antennas; forming a third signal by adding the second signal received via the first antenna and the second signal received via the third antenna; delaying the difference signal; and comparing a fist polarity of the delayed difference signal with a second polarity of the third signal.

Abstract: Process for estimating a precipitation rate by means of a bipolar radar, characterized by the following various steps: the differential phase &PHgr;dp and the attenuated reflectivity Z according to at least one of the polarizations H or V are measured by means of said bipolar radar, over a given interval [r1, r0] of path radius r with respect to said radar; an estimate of the value K(r0) of the attenuation at r0 is determined from the attenuated reflectivity profile thus measured, as well as from the difference in the differential phase between r0 and r1; an estimate K(r) of the specific attenuation at r as a function of the attenuation K(r0) thus determined and of the attenuated reflectivity profile Z(r) is determined; the rate of precipitation R(r) is determined knowing K(r).

Abstract: An apparatus and method for generating an electromagnetic environment in which the free field, plane wave response of electronic systems of an electrically large (greater than several wavelengths in its longest dimension) object, or objects, under test can be measured in the electromagnetic radiating near field of the transmitter array apparatus. The apparatus comprises: (1) one or more transmitting station(s), each station home to an array of radiating elements; (2) a software operating system and computer that controls the electronic circuits of the apparatus and executes an optimizing algorithm based on a Genetic Algorithm to control the radiation of each transmitting station; and (3) mechanical and electrical circuits that enable the apparatus to conduct self calibration and adjustment as required. In operation, the apparatus is placed and distributed about an object under test.

Abstract: This invention concerns a repeater jamming transmitter (2), and a casing arrangement with repeater jamming transmitter. The repeater jamming transmitter (2) comprises transmitter antenna (7), receiver antenna (8) and electronics part (10) with amplifier and control circuits. In order to avoid self-oscillation caused by leakage between the transmitter antenna (7) and the receiver antenna (8) and to maintain the isolation a special connection arrangement (7,8,10) is included in the repeater jamming transmitter. By means of the connection arrangement the amplification of the repeater jamming transmitter can be increased without self-oscillation arising.

Abstract: Described herein is a circularly polarizing radar transponder. The circularly polarizing radar transponder comprises a helical type circularly polarizing antenna unit for receiving all of a circularly polarized wave, a vertically polarized wave and a horizontally polarized wave therein, a receiver unit connected to the helical type circularly polarizing antenna unit, a transmitter unit for generating a plurality of pulses with a radio wave received by the receiver unit as a trigger, and a battery unit for supplying power to these receiver and transmitter units.

Abstract: An icing hazard avoidance system and method utilizes a forward-looking, single frequency, dual-polarization pulse radar system as well as temperature sensing means to determine if supercooled liquid water (SLW) drops are present in an aircraft's flight path. A processor determines the ratio of co-polarized and cross-polarized returns. This ratio and the temperature of the atmosphere indicate if SLW drops exists. If an icing hazard is determined, an indicator in the cockpit of the aircraft alerts pilots so that avoidance measures may be taken.

Abstract: Faraday Rotation causes rotation of the plane of polarization of plane polarised radiation emitted by a radar e.g. a synthetic aperture radar and, if returns polarized in orthogonal planes are measured at the synthetic aperture radar in order to determine polarimetric characteristics of the ground, which could show up features of the ground such as crop patterns, the measurements made at the SAR are contaminated by the Faraday Rotation. In the invention, the transmitted plane polarized beam is pre-rotated in transmitter 9, the radar returns in receiver 13 are mathematically adjusted in signal formatting 14, 15 to compensate for just the pre-rotated angle, to produce data streams on downlink 16 uncontaminated by the Faraday Rotation.

Abstract: Methods and apparatus for detecting objects are disclosed. In one embodiment of the invention, a person entering a secured or “Safe Zone™” is illuminated with low-power polarized radio waves. Differently polarized waves which are reflected back from the person are collected and measured. Persons carrying a concealed weapon such as a handgun are detected by calculating the difference of a pair of differences between levels of different polarized reflected energy. Alternative embodiments of the invention may be used to detect a wide variety of objects other than concealed firearms. The invention may be used for inventory control or to thwart shoplifting.

Abstract: A system for wire detection comprising a transmitter for transmitting multi-polarity waves, means for receiving waves reflected off target and means for analyzing the polarization of the reflected waves to detect linearly polarized echoes characteristic of wires and to issue a warning indicative of the presence of a wire. The wavelength of the transmitted waves is larger than the diameter of the wires to be detected. A method for wire detection comprising the following steps, for each of a plurality of angles U between 0 and 180 degrees: a. Transmit pulses of electromagnetic waves having a linear polarization at an angle U to horizontal; b. Receive echoes at the same polarization angle U; c. Prepare a map M(U, R) with the magnitude of the received echo for each angle U and each ground cell at range R.

Abstract: A method and apparatus for generating microwave signal frequencies. An incident reference signal is provided. A first stimulus signal is also provided, the first stimulus signal having a first polarization and having a first predetermined relationship with the incident reference signal. A second stimulus signal is also provided, the second stimulus signal having a second polarization and having a second predetermined relationship with the incident reference signal. The incident reference signal is split into a first polarization reference signal and into a second polarization reference signal. The first stimulus signal is coupled with the first polarization reference signal to provide first polarization mixed signals. The second stimulus signal is coupled with the second polarization reference signal to provide second polarization mixed signals.

Abstract: A device for the unambiguous measurement of the angle of roll of a projectile, comprises at least a radar equipped with means of processing and sending a signal to the casing of the projectile in at least one direction of incident polarization; a set of parallel grooves made on the casing, the depth of which is modulated dissymmetrically with respect to the axis of symmetry of the projectile; the axis of symmetry of the projectile not passing through the point of the antenna of the radar where the antenna beam is generated, the processing means analyzing, in reception, a signal back-scattered by the casing of the projectile, the signal being modulated as a function of the angle of roll of the projectile, the modulation having two maximum local values corresponding to two angular roll positions of the projectile such that the polarization {right arrow over (E)} is parallel to the grooves, the processing means removing the 180° ambiguity by comparing the levels of the local maximum values.

Abstract: Methods and apparatus for detecting objects are disclosed. In one embodiment of the invention, a person entering a secured or “Safe Zone™” is illuminated with low-power polarized radio waves. Differently polarized waves which are reflected back from the person are collected and measured. In a preferred embodiment of the invention, concealed weapons are detected by calculating the difference of a pair of differences between levels of different polarized reflected energy in the time domain, and by using signal processing methods and apparatus to improve the reliability of the detection process. Alternative embodiments of the invention may be used to detect a wide variety of objects other than concealed firearms. The invention may be used for inventory control or to thwart shoplifting.

Abstract: A system of enhancing target detection in a polarization modulated signaling system for detecting targets through one or more given media. A polarization modulated signal is generated and transmitted in the given medium which is the complex conjugate of the polarization modulated response over time of the combined medium and target. The wave equation for transmission through the medium, reflectance from the target and transmission through the one or more given media, is solved and the polarization modulation of the polarization modulated signal is adjusted to match the polarization response over time for maximum propagation through the one or more given media and maximum reflectance from the target over time.

Abstract: Apparatus and method for eliminating an interference signal from a desired signal where a difference of polarization exists or can be made to exist. The desired signal is received on a first antenna of appropriate polarization and the interference signal is received via another port of the same antenna or a second antenna polarized ninety degrees away from the first. The signal received via the other polarization is adjusted for amplitude and phase so that all interference will be cancelled when both signals are subtracted in a summing junction. In the case where the interference and desired signals do not have polarization differences, provision is made to change the polarization of the desired signal.

Abstract: A dual mode microwave vector controller apparatus is disclosed for controlling amplitude and phase characteristics of RF signals. A first set of phase shifting integrated circuit chips (PSICs) is disposed on a semiconductor substrate, each PSIC having an input port for receiving an RF signal and an output port for transmitting amplitude and phase modulated RF signals. A second set of PSICs is disposed on a semiconductor substrate, each PSIC having an input port for receiving an RF signal and an output port for transmitting amplitude and phase modulated RF signals. A first reciprocal planar magic tee integrated circuit chip (RPMT) is disposed on a semiconductor substrate and sandwichedly coupled between the first and second sets of PSICs, having input ports for receiving RF input signals from one set of PSICs and having output ports for transmitting output RF signals corresponding to the sum and difference of the RF input signals to the other set of PSICs.

Abstract: The invention concerns the radars jamming able to coherent side looking cancellation. From a jamming source (SBR), it is created two channels supplying respectively transmission amplifiers (AE1 and AE2) followed by antennas (AP1 and AP2) operating in different polarizations. The former at least of the two channels is subject to fast time variations with respect to the latter, for example with a line of programmable length (LLP).

Abstract: A system 10 for reducing clutter in passive radiometric images of the ocean surface, the system including: a first polarizer 12 for generating a vertically polarized image of a selected patch of the ocean surface, the vertically polarized image including a first set of radiance data; a second polarizer 14 for generating a horizontally polarized image of the selected patch of the ocean surface, the horizontally polarized image including a second set of radiance data; a processor 16 for computing a clutter reduction weighting factor from the first and the second sets of radiance data; and means 18 for combining the first set of radiance data with the second set of radiance data utilizing the weighting factor to generate a combined image with reduced wave clutter. The processor 16 includes means for computing a weighting factor for minimizing clutter-associated variance in the weighted combination of the first and the second sets of radiance data.

Abstract: This target detection polarimetrical processing circuit comprises, in parallel, a polarimetrical CFAR detector provided with a target detection output, a polarimetrical clutter-rejection filter associated with a CFAR detector provided with a target detection output and a bank of polarimetrical filters associated with CFAR detectors provided with target detection outputs, and an "OR" type logic circuit combining the different target detection outputs and a selection circuit activating the polarimetrical clutter-rejection filter and disabling the bank of polarimetrical filters when the degree of polarization of the clutter exceeds a certain threshold and conversely disabling the polarimetrical clutter-rejection filter and activating the bank of polarimetrical filters when the degree of polarization of the clutter is below said threshold.

Abstract: This invention relates to a method and apparatus by which a coarse estimate of radar signal polarisation can be obtained. An array comprises at least three differently directed detectors. The polarisation is estimated by measuring an amplitude relationship, such as a ratio of amplitudes, for two adjacent detectors and for two non-adjacent detectors. This provides sufficient information to obtain a coarse estimate of the polarisation state, obtainable by using the value of the amplitude relationship for the two adjacent detectors together with a look-up table to estimate values of the amplitude relationship for the two non-adjacent detectors for different polarisation states, and then comparing the measured and estimated values for this amplitude relationship.

Abstract: A radar system in which a frequency agile synthesizer is used to provide rapid frequency shifts and in which measures are taken to maintain phase coherency. The system is fully coherent such that all signals are derived from a common source and are capable of high pulse repetition rates in excess of 1 MHz. There are no inherent transmit duty cycle restrictions and the system is able to transmit complex phase and frequency modulated waveforms. A frequency interleaving scheme is used to resolve range ambiguities at high pulse repetition frequencies and the use of a complementary phase coding scheme allows a high range resolution processing with the transmitted waveforms.

Abstract: An adaptive polarization diversity system for radio link communication. The system includes a base station antenna for transmitting either a clockwise polarized transmission or a counterclockwise polarized transmission, the transmission including a training pilot signal. The system further includes at least one subscriber unit for receiving the transmission, the unit including a first subscriber unit antenna for receiving a clockwise polarized transmission, a second subscriber unit antenna for receiving a counter-clockwise polarized transmission, and a dual channel receiver for adaptively combining the clockwise polarized transmission with the counterclockwise polarized transmission in proportion to first and second weights, respectively, the dual channel receiver determining the first and second weights so as to substantially optimally receive the training pilot signal.

Abstract: The invention concerns a microwave transmit/receive (T/R) circuit for a polarization synthesizer array antenna, especially a radar antenna. According to the invention the required polarization is obtained by applying two signals to an array element on two orthogonal feed paths with a variable phase difference between the two paths, both of which function simultaneously. In a preferred embodiment both transmit channels are provided with two power amplifiers which each amplify a signal from an in-phase power divider or a hybrid coupler, with a one-bit or two-bit controllable phase-shifter adding a phase-shift of 0.degree., 90.degree. or 180.degree. to synthesize orthogonal linear or circular polarizations. In a preferred embodiment the circuit according to the invention is partly or entirely implemented in monolithic (MMIC) technology. The invention also concerns an antenna including a T/R circuit as specified hereinabove.

Abstract: The disclosure is directed to a method and apparatus for remotely sensing electrical activity and potential for lightning occurrence. The disclosure is particularly directed to the use of such an apparatus and method to detect the electrical alignment of particles in upper levels of electrified storms. Storms are illuminated by radar in one or more orthogonal polarizations and the co-polar and cross-polar returns are correlated coherently and incoherently. The correlation coefficient, or a function thereof, is examined to determine the degree of particle alignment, and therefore the degree of electrification and potential for lightning occurrence. The phase of the correlation computation, in coherent processing, also detects particle alignment, which can be incorporated in the predictive decision. Correlation and phase can be displayed, recorded or, utilized for a prediction or warning.

Abstract: A measurement device (103) and method determines various metrics between a vehicle (101) and a ground surface (105) using a transmitter-antenna (109) for emitting energy including a portion directed down toward the ground surface. A receiving antenna (115), has a portion oriented facing toward the transmitter-antenna for receiving a portion of the emitting energy along a direct path (117), and a portion oriented facing downwardly toward the ground surface for receiving a portion of the emitting energy reflected from the ground surface along a reflected path (113). A decoder provides separate indications of forward (121) and sideward (123) velocity relative to motion of the vehicle along the ground surface.

Abstract: The polarimetric technique of measuring azimuth direction terrain slopes utilizes a polarimetric synthetic aperture radar (SAR) to provide a direct measure of terrain azimuthal slopes and a derived estimate of terrain elevation. Utilizing this measure of the azimuthal slopes and estimated terrain elevations, a one-dimensional terrain slope map over a wide area may be produced without any prior knowledge of the terrain. Utilizing the method of steepest descent (or gradients) the polarimetric orientation of the peak (maximum) of the signature is determined for each image pixel. The terrain elevations are derived by integrating the slopes in the azimuthal direction and may be further refined so as to obtain absolute, rather than relative, elevation values by independently knowing at least one elevation "tie-point" along each slope profile being integrated. These orientations are proportional to terrain slope in the azimuthal direction.

Abstract: A Reduced Radar Cross-Section RF Seeker Front-End interrogates a potential arget by issuing interrogation radiation toward the target and receiving and analyzing a portion of the radiation that reflects back from various surfaces of the targeted object while, at the same time, the Front-End reduces the likelihood of its own discovery by the enemy. The Front-End accomplishes the reduction by absorbing radiation directed toward it by an enemy radar or anti-tactical missile rather than allowing the radiation to be reflected back. Such absorption greatly diminishes the availability of signature reflection that belligerents rely on to identify hostile forces on the battlefield.

Abstract: A polarimetric Doppler weather radar system which allows measurement of linear orthogonal polarimetric variables without a switch by using simultaneous transmission of horizontally and vertically polarized waves. This is accomplished by splitting the transmitted power into two waveguides and combining them with an orthomode coupler at the antenna feed. Thus, in general the transmitted polarization is elliptical but with equal amount of power in horizontal and vertical polarization. On reception, the power is divided, at the orthomode coupler, into linear horizontal and vertical components. These components are processed and combined to yield Doppler and polarimetric information about storm structure.

Abstract: Disclosed is a method for the discriminating of obstacles by means of a radar, and its different applications to the measurement of a liquid in a tank or vessel, or again to the elimination of unwanted or parasitic echos coming notably from the ground, for radars mounted on vehicles or controlling vehicle traffic. To implement the method, the obstacle to be discriminated must have a substantially plane surface. The disclosed method then consists in successively transmitting substantially plane waves at slightly different angular frequencies .omega..sub.i, each wave being furthermore sent with two different polarizations p and p' chosen in such a way that these different coefficients of reflection on the obstacles according to the incidence of the waves give a criterion of discrimination. The processing at reception depends on the use (measurement of distance, elimination of parasitic echos etc.).

Abstract: The total energy, wave type, orientation and rotation of an incident electromagnetic signal having an unknown polarization is identified through single channel frequency domain signal analysis of the incident electromagnetic wave power as measured by an orthogonally polarized electromagnetic sensor. A controlled switch samples between the power measurements at each orthogonal output of the sensor to generate a signal comprised of a carrier frequency component and two sideband frequency components in the frequency domain. The sampled radio frequency signal is down converted by a single channel receiver to an intermediate frequency where the carrier and one sideband frequency component are separated and coherently shifted to the same frequency. A phase detector and ratiometer measure the relative phase and amplitude differences between the separated carrier and sideband frequency components to identify the wave type, orientation and rotation of the incident electromagnetic signal.

Abstract: A system for an unambiguous determining of the roll angle attitude of a rotating projectile, grenade, missile or the like with the aid of a polarized electromagnetic radiation, comprises a transmitter for emitting a position-determining polarized radiation (space wave) in the direction of the projectile and a receiver arranged in the projectile for receiving the emitted radiation. The emitted space wave is made up of a carrier wave reference with frequency f.sub.1 which has been phase-modulated with a modulation frequency f.sub.2, wherein f.sub.2 is<<f.sub.1 and wherein f.sub.2 forms a submultiple of the carrier wave frequency f.sub.1.

Abstract: An image forming method using a thermal transfer, wherein a dye-receptive layer on a transfer film is transferred to a print sheet and then dye layers on a dye transfer film are superposed on the dye-receptive layer and subjected to an image forming operation of a thermal head so that an image is transferred to the dye-receptive layer. In order to transfer the dye-receptive layer to the print sheet uniformly to enable subsequent formation of an excellent dye image, the quantity of thermal energy being applied by the thermal head to the transfer film is decreased with elapse of time. This principle can also be used for transferring a protective layer to the print sheet on which a dye image has been formed.

Abstract: A system including a first station (1) known as a beacon and at least one second station (2) known as a badge, each station having a transmission channel with an antenna and a reception channel with an antenna.To allow multiplex exchanges, using simultaneous transmission and reception, the two antennas (6, 11) (13, 15) in any given station are decoupled by cross-polarization but antennas which communicate with each other (6, 13) (11, 15) have compatible polarization.Applications to identification systems using microwave transmission.

Abstract: A fast switching, variably polarized lens is placed in front of a radar antenna which radiates an electromagnetic wave having any fixed polarization. The radiated electromagnetic wave is coupled to the lens and the switching elements within the lens transform the polarization of the radiated electromagnetic wave as commanded. Each transmit pulse may take on any polarization which the lens is capable of providing independent of the polarization of the previous transmit pulse. Similarly, during receive mode the lens can be set up to allow the radar system to receive a return signal of any polarization independent of the polarization of the return signal's associated transmit signal.

Abstract: Method and arrangement for an airborne radar system particularly adapted to detect large metal targets that are concealed from the air by camouflage or natural foliage. The arrangement includes an antenna that transmits a continuous wave electromagnetic signal having a selectable frequency that preferably has a wave length generally twice the length of an anticipated target and which is carried by a flying vehicle. The frequency of the transmitted signal is chosen to provide maximum penetration of the camouflage or natural foliage and maximum re-radiation from a metal target. Receivers connected to an in-line receiving antenna and to a crossed receiving antenna carried by a flying vehicle detect the radiation that is reflected from the terrain and a target with the same polarization as that transmitted. The co-linear antenna and receiver respond to the reflected radiation while the cross-polarized antenna does not detect this reflected radiation.

Abstract: A process for mapping a region of interest using polarimetric radar signals is disclosed. The process provides for the polarimetric calibration of polarized signal data to account for distortions arising from cross-talk and channel imbalance during signal transmission and/or reception. Moreover, the process also can be used to correct for ionospheric signal distortions of polarized signals with low frequencies prone to Faraday rotations upon encountering the ionosphere. Such calibrations are accomplished with a reduced number of, typically ground-based, signal reflection devices used for calibrating the polarimetric signals to compensate for the above distortions.

Abstract: A process for cancelling the effects of noise jamming in a radar system having a dual-polarization monopulse antenna, a computer processor, and target detection algorithms, wherein the noise jamming produced by a hostile electronic countermeasure on a target is cancelled so as to detect the target in the optimum detection channel. The process consists of the steps of receiving signals from multiple monopulse polarization aperture combinations of the radar antenna, sampling the signals from the radar antenna, digitizing the sampled signals, calculating combination values based upon the samples of the digitized signals, computing several potential target detection channel signals based upon the combination values and samples of the digitized signals, applying the detection channel signals to the computer processor and selecting the optimum detection channel signal for detection of the target using the computer processing whereby the signal is then applied to target detection algorithm of the radar processor.

Abstract: A tunable high-frequency device using a superconductive thin layer with a thickness smaller than the thickness of penetration of a magnetic field is positioned on a dielectric layer. Also included is a means for varying the density of the Cooper pairs of the superconductive thin layer.

Abstract: Disclosed is a method and an apparatus which act as a retroreflector of circularly polarized electromagnetic radiation over a broad range of incident angles. The apparatus includes dipole antenna pairs which are orthogonally disposed in relation to one another about a central point to create antennas which consist, for example, of crossed dipoles but can be other circular polarization sensitive antennas. Antenna pairs are then arranged symmetrically in an array and interconnected by means which control the circular polarization of the returned signals to provide retroreflection of impinging signals while maintaining the same sense of polarization. The array thereby provides enhancement of the radar cross-section of a target when circularly polarized radar is employed. Conversely, the array can be connected so as to enhance opposite-polarization returns should there be any desire to do so.

Abstract: A transmission/reception module suitable for use in electronically phase-controlled antennas for a synthetic aperture radar includes a circulator provided for each individual radiator element terminal to achieve vertical and horizontal polarization. A low-noise amplifier is connected to the circulator in the reception path. A high-power amplifier is connected to the circulator in the transmission path. The two separate polarization reception channels each include a low-noise amplifier. The two separate polarization transmission channels each include a high-power amplifier. The reception channels and transmission channels are respectively connected to a polarization change-over. Switching arms of the polarization change-over are then connected to either the reception contact or the transmission contact of the transmission/reception switch.

Abstract: A method and system for detecting wire in a terrain avoidance, terrain following, or a terrain obstacle system. Radiant energy pulses orthogonally polarized are alternately transmitted. Selected dimensions of a full scattering matrix of adjacent reflected pulses for a particular range are collected and combined to form a null matrix. A null matrix with the two reflected pulses being within a predetermined distance from one another is detected as a wire.

Abstract: A data transmission and/or acquisition device and method are disclosed. The said device and method use two cross polarizations of an electromagnetic wave and a magnetic recording device. The invention pertains to phase/amplitude modulation using two phase-modulated signals transmitted on two orthogonal polarizations. At reception, the vector sum of the two signals is added taken. The resultant signal is amplitude-modulated and/or phase-modulated. The invention can be applied especially to television and radio transmitters, radars and telecommunications equipment.

Abstract: Identification system constituted by an interrogation station or interrogator 1 itself formed by a radio frequency wave transceiver and preferably on an ultra frequency wave length 5, and, on the other hand, by a responder unit 2 adapted to receive the wave and to re-emit (echo) it following the given coded modulation to the responder unit. The interrogator is adapted to receive this echoing wave 11 and to demodulate it in order to derive the identification code therefrom. The interrogator has an emission antenna adapted to emit an inquiry signal constituted by a radio wave emitted in plane polarization. The responder unit has two adjacent antennas, respectively, for the reception of the inquiry wave and for its re-emission (echo) after modulation. The two antennas are of the circular polarization type and each functioning in a direction of rotation of the polarization opposite with respect to each other.

Abstract: Apparatus and method for eliminating an interference signal from a desired signal where a difference of polarization exists or can be made to exist. The desired signal is received on a first antenna of appropriate polarization and the interference signal is received via another port of the same antenna or a second antenna polarized ninety degrees away from the first. The signal received via the other polarization is adjusted for amplitude and phase so that all interference will be cancelled when both signals are subtracted in a summing junction. In the case where the interference and desired signals do not have polarization differences, provision is made to change the polarization of the desired signal.

Abstract: A multi-octave bandwidth antenna is disclosed which radiates with variable polarizations using: a metal ground plane, first and second blade antenna elements, first and second coaxial transmission line feeds, and a 180.degree. hybrid coupler. The two blade antenna elements are fixed above the metal ground plane in proximity with each other, and fed respectively by the central conductors of the first and second coaxial transmission line feeds. The 180.degree. hybrid coupler has a sum and difference port to control the polarization of waveforms of the antenna.