Abstract: A dual polarization active microwave reflector with electronic scanning, configured to be illuminated by a microwave source to form an antenna. The reflector includes two imbricated waveguide arrays, the bottom of each waveguide array being closed by a phase shift circuit carrying out the reflection and the phase shifting of the wave that it receives. One of the two waveguide arrays is configured to receive a first polarization and the other waveguide array is configured to receive a polarization perpendicular to the first polarization.

Abstract: The present invention relates to a dual polarization active microwave reflector with electronic scanning, capable of being illuminated by a microwave source in order to form an antenna.

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: A reflector of an antenna in a radar system subject to jamming carries a multiplicity of localized phase shifters which are sequentially controlled by a processor to introduce certain phase modifications into incoming signals reflected toward an associated radiator. The processor, operating on branched-off portions of the incoming signals, compares the magnitudes of the signals received in the several operational states of each phase shifter and maintains that operational state for which the signal level is at a minimum. The comparisons may be carried out on signals received at the end of a signal-transmission cycle, lacking a useful component.

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: The present invention concerns mainly a filter, a phase-measuring device and a method to apply said filter. The main object of the invention is a phase-measuring device. The use of adapted filters (140) enables the increasing of the signal/noise ratio of a received signal. However, if several samples of the signal are sent, each having a different phase, the signal present at the output of the adapted filter at any given instant risks being a mixture of the phase of two successive samples. The use of an odd value filter (141) makes it possible to determine the only instants during which the phase measurement corresponds to the phase of a single sample of the signal. The invention can be applied chiefly to the demodulation, detection or decoding of television and radio broadcasts or phase-modulated data transmissions.

Abstract: A conical sweep array antenna has a flat antenna structure having a plurality of microstrip sources disposed in a plurality of sections. Preferably, each section includes a plurality of sources. The flat antenna also has at least one source disposed outside any of the sections. A phase-shifting device phase-shifts the plurality of sources to cause a conical sweep pattern of the flat antenna. Also, the phase-shifter device provides a constant phase-shift to the one source which is not disposed in any section. The presence of the nonphase-shifted source improves the radiating diagram of the antenna of the invention, particularly by reducing the coma lobe.

Abstract: Pulse-compression method employing space-coding, according to which a plurality of pulsed signals are emitted, simultaneously, for a time (1/.DELTA.f), at frequencies which are uniformly graded by an increment (.DELTA.f), the pulsed signals which are returned by any target being spatially compressed, the compression factor being equal to the number of signals which were emitted simultaneously.

Abstract: A microwave reflector having metallic surfaces and nonmetallic surfaces is perfectly reflecting for the waves of a first polarization and partly transparent for the waves of a second polarization orthogonal to the first. The reflector is primarily applicable to radar systems.

Abstract: The apparatus according to the invention relates to a guided vehicle control process and apparatus which comprises passive beacons, as well as radars permitting the detection thereof. The presence or absence of a beacon permits the automatic control of a train, e.g. with a view to automating the driving thereof. The apparatus according to the invention uses retrodirectional beacons and/or beacons inducing a polarization rotation of the radiation received. The use of retrodirectional beacons induces a change of frequency by Doppler effect of the reflected radiation. The change of the Doppler frequency and/or the polarization rotation of the radiation improves the signal-clutter ratio and/or the separation of the transmission and reception channels.

Abstract: Secondary lobe cancellation (SLC) is used to reduce the power of jamming signals received by the sidelobes of a main radar antenna. The signal from the radiation pattern of the main antenna is summed with signals from auxiliary radiation patterns. Each auxiliary pattern is chosen to be directional, to have a null or at least a gain minimum in the direction of maximum radiation in the main antenna pattern, to have its phase center close to that of the main antenna pattern, and to have gain minimums in those directions for which the sidelobes of the main antenna pattern are low enough to be insensitive to jamming signals. The various patterns may all be derived from an array antenna, e.g. a multibeam antenna, an aplanatic lens antenna, or a chandelier fed antenna.

Abstract: An antenna having two crossed cylindro-parabolic reflectors in which the generatrices of said reflectors are orthogonal. The source is placed close to the center of the main reflector, which is further provided with polarization rotation means. The auxiliary reflector is placed facing the main reflector and it is such that it is transparent to a wave polarized linearly in one direction and reflecting to the waves polarized in an orthogonal direction.

Abstract: The invention relates to an assembly of main and auxiliary antennas for an electronic scanning radar. Each auxiliary antenna uses all or part of the elementary radiation sources of the main antenna. The energy received by each of them is sampled by a coupler and then phase shifted by an angle .phi.i in an adjustable phase shift circuit. The respective outputs of the phase shift circuits are concentrated within a waveguide. The auxiliary antennas are of the same type as the main antenna. The invention is applicable to radars equipped with an anti-jamming device.

Abstract: Each radiating slot having a length L in the vicinity of the operating wavelength .lambda. of a direct-radiation slotted rectangular waveguide is placed on one side of the waveguide so as to be parallel to the lines of current flow and is provided with a transverse stepped section formed at the center of the slot at right angles to the current lines.

Abstract: Disclosed is a conically scanning antenna emitting a beam of radiation which is modulated in phase but not in amplitude. In certain embodiments the antenna comprises a source of radiation including a horn illuminating a reflector, the horn being either inclined to the reflector axis or juxtaposed with a prism imparting such inclination to its direction of maximum radiation. The inclined horn or the prism is rotated about the axis by drive means supplying a reference scanning signal to a processor.

Abstract: A disk-type antenna array is described with its supply device. The antenna is supplied with an electromagnetic wave having circular polarization in the TE.sub.11 mode delivered through a particular coupling means.

Abstract: An antenna structure includes an at least partly parabolic main reflector and an auxiliary reflector of generally similar configuration, the two reflectors having confronting concave surfaces and lying respectively above and below a horizontal plane including a common focus of these surfaces. A corrugated horn illuminating the auxiliary reflector extends at the level of the latter, with a substantially horizontal axis, between vertical planes passing through the vertex of the parabolic main-reflector surface and through the common focus; in one embodiment, the horn forms with the auxiliary reflector a unitary assembly closed on all sides except for an upper aperture facing the main reflector.

Abstract: A nondispersive array antenna comprises a linear primary radiator array in the form of a slotted waveguide emitting high-frequency waves toward a linear secondary radiator array including an acute angle .alpha. with the primary array, this angle .alpha. being approximately equal to (.pi./4) -(.theta..sub.o /2) where .theta..sub.o is the angle included by the emitted beam with the perpendicular to the waveguide in the plane of radiation. The secondary array includes a row of elemental radiation receivers on the side facing the primary array and as many elemental radiation emitters on the opposite side; each radiation receiver is linked to a respective radiation emitter through a coupling introducing a predetermined phase shift between incoming and outgoing radiation, these phase shifts compensating for the phase displacement occurring along the arrays in the free-space propagation of the waves from one array to the other.

Abstract: An arrangement is described for extracting divergence-measuring modes from a corrugated guide connected on the one hand to a corrugated horn and on the other to a utilization device. The arrangement includes at least two pairs of collector waveguides lying in diametrically opposite positions along the corrugated guide to which they are coupled by slots formed in the wall of the corrugated guide in which the divergence-measuring modes are propagated. Two, at least, of these modes are extracted as a function of their phase velocity and are processed to produce divergence-measuring signals. The arrangement is advantageously used in antennas for tracking satellites or missiles.

Abstract: A horn of circular or rectangular cross-section has a multiplicity of circumferential grooves on its diverging inner peripheral wall; these grooves have a depth on the order of a quarter wavelength, at the upper end of the band of operating frequencies, and are separated by distances up to half a wavelength. Other discontinuities in this peripheral surface, serving to pick up odd modes for divergence-measuring purposes, are in the form of probes transverse to the horn wall disposed in one or more grooves or throughgoing slots lying between certain grooves or within same. The discontinuities may be arranged in pairs of diametrically opposite probes or slots, e.g. with two mutually orthogonal pairs disposed in a common transverse plane; probes in adjoining grooves may be interconnected by a transmission line.