Abstract: A method and system for creating a constellation of electronic devices for providing optical or radio-frequency operations relating to earth surface data collection applications on a predetermined geographical area. On each of a plurality of (commercial) airplanes at least one electronic device from the constellation is provided, and during its flight each airplane has a flight path over at least a portion of the geographical area. Each electronic device is configured for the operations during the flight with an earth coverage range for the operations determined by an individual airplane coverage range of a portion of the earth surface as provided by the associated airplane. One or more electronic devices are activated for the operations when the individual airplane coverage of the one or more airplanes associated with the one or more electronic devices is within the geographical area.

Abstract: A receive and/or transmit microwave planar array antenna is of the multiplate stack type comprising a plurality of slot radiating elements disposed along the rows and the columns of a matrix. The basic stack comprises three ground plates incorporating openings and two independent excitation circuit planes, enabling transmission or reception of two inclined beams. At least two other excitation circuit planes are provided so that each beam can additionally have dual polarization. The excitation circuits are microstrips, coplanar waveguides, dipole lines, of the loop or slot type, or a combination of such lines. Two consecutive lines are oriented at 90.degree. to each other. Applications include individual reception from two geostationary television satellites.

Abstract: A duplexing circularly polarized composite antenna comprises at least one pair of radiator elements supportings orthogonal (vertical and horizontal) linear polarization. One radiator element is fed with a signal with a phase difference of 90.degree. relative to the signal fed to the other radiator element. Each radiator element transmits and/or receives signals at two different frequencies having orthogonal polarization. One radiator element operates at a first frequency with vertical polarization and a second frequency with horizontal polarization. The other radiator element operates at the first frequency with horizontal polarization and at the second frequency with vertical polarization.

Abstract: A planar antenna of the kind comprising feed lines disposed in a flat circuit and cooperating by hyperfrequency coupling with a metal ground plane plate pierced by apertures has the feed lines presenting a termination juxtaposed with each aperture. A lower ground plane plate is disposed at a distance of approximately a quarter wavelength from the apertured metal plate. The apertured metal plate comprises a metal coating deposited on a dielectric substrate. The feed line comprise central conductors disposed in channels which open into the apertures. The array of apertures, channels and conductors can be produced on the dielectric substate by single face printed circuit techniques. The antenna may be used for the reception of direct broadcasts from satellites.

Abstract: A large scan antenna, particularly for embarked use on board a satellite and for operation in the ultrahigh frequency range, of the type formed of a feed and a main fixed secondary reflector, the antenna being readily foldable into a launching configuration with a minimum of component elements, and comprising at least one guide G each formed of a first and a second parabolic secondary reflectors (12, 13) aligned optically along the axis of the wave guide G between the feed (10) and the main reflector (15), said wave guide G being on the one hand variable in length by moving at least one (13) of said secondary reflectors with respect to the other (12) along the axis (14) of the wave guide G, and on the other hand, rotatable about the axis (11) of the feed (10).

Abstract: In a high-frequency antenna comprising a plurality of horns 1, phase differences arising in these horns 1 would need to be corrected. Such phase differences are avoided by providing a planar design of the antenna comprising four adjacent horns 1 fed by T-shaped power divider 6, being linear and symmetrical.

Abstract: Inside a parallelepipedic guide section there is provided at least one partition located so as to divide the inner volume of the guide section into a main waveguide portion capable of supporting an orthogonally polarized signal and two secondary waveguide portions extending in the same direction as the main waveguide portion. The secondary waveguide portions are so dimensioned such that one of these waveguide portions is capable of supporting a horizontally polarized signal and that the second waveguide portion is capable of supporting a vertically polarized signal.

Abstract: A high-frequency antenna unit module for receiving or transmitting a rectilinearly polarized wave including radiating elements in the form of horns and a waveguide supply network. The module has four horns with square apertures which form a bidimensional network in a plane parallel to a reference plane P. The supply network is of the "planar" type having first pairs of opposing sidewalls extending in a direction parallel to P, and of the "tree-structured" type because all of the horns are fed in-phase by T-shaped power dividers. The waveguide sections have sidewall dimensions a and b, where a>b and a=.lambda..sub.c /2. The dimension b is the width of each of the opposing sidewalls extending parallel to P, and a is the height of opposing sidewalls extending perpendicularly to P and connecting each of the first pairs of sidewalls. The network is suitable for propagating the TE.sub.01 mode along which the electric field vector E propagates in parallel with the plane P.

Abstract: A rectilinear waveguide junction apparatus in which the input and output guides are parallel to the longitudinal axis of the apparatus. This apparatus is characterized in that it takes the form of a parallelipiped guide the internal volume of which is divided up by metal partitions which form two parallel input guides, two parallel output guides and a main intermediate guide of same section as the parallelipiped guide. This apparatus is used in very high frequency circuits, for example the supply circuits for satellite or radar antennae.

Abstract: Antenna output for a planar antenna comprising an array of receiving elements provided by two networks (20, 30) of high frequency transmission lines and three sheets (10, 40, 50). The first sheet (10) comprises first cavities (11), the first and second transmission line networks are planar, located respectively on either side of this first sheet and, for signal reception, coupled to each of the cavities by a corresponding number of distinct ends forming exciting probes along two perpendicular axes. The third and second sheets (40, 50) are located on the other side of both of these networks and comprise second and third cavities (41, 51) which are in line with the first cavities. The third cavities are short-circuited in a plane parallel to the surfaces of the sheets, and these sheets are made of a metal or of a dielectric material having metal-plated walls of the cavities.

Abstract: A flat microwave antenna comprising a network of emitting or receiving elements constructed by means of the printed circuit technique on a dielectric support. The elements are arranged on a series of radii (A to H) and are relatively equidistant on each of these radii. In the simplest construction, the radii are equiangularly spaced and the number of elements per radius is equal to 2.sup.n, n being a positive integer proportional to the length of each radial segment.

Abstract: A radiating or receiving element for orthogonally polarized high-frequency signals comprises, on both sides of a first layer having a first cavity, first and second perpendicular high-frequency transmission lines and at the other side of the transmission lines a second layer having a second cavity and a third layer having a third cavity facing the other two cavities but short-circuited so as to form a reflecting plane, the transmission lines being constituted by symmetrical slots and conducting strips, which are provided in the median plane of these lines and whose ends project into the cavities to form exciting probes whose lengths are different and chosen such that for any predetermined thickness of the first layer, the pairs of values: lengths of the end of a probe/distance of the probe to the sole reflecting plane correspond to an experimentally maximum or nearly maximum coupling between each of the probes and the propagation medium.

Abstract: A planar high-frequency antenna having radiating elements for high-frequency signals includes at least two facing conductive plates provided with oppositely-arranged openings which cooperate to form respective cavities. Disposed between each pair of facing plates is a thin dielectric sheet supporting an array of strip conductors of coaxial lines forming suspended-substrate microstrip lines with these plates. Ends of the strip conductors extend into the cavities and form radiating elements. Each thin dielectric sheet is held in place between the facing plates by means of positioning spacers provided on the faces of these plates. The spacers are located in areas where there are no conductors on the dielectric sheet and are sufficiently remote from each other such that at least two cavities and/or lines of the network of strip conductors are located between any two spacers.