Agence Spatiale Europeenne

Agence Spatiale Europeene

Other

Antoine G Roederer

Emmanuel Rammos

Simon John Stirland

Marco Lisi

Cornelis G Van't Klooster

Gerald A Crone

Cyril Mangenot

Peter Balling

Martin P Maximo

Guilio Doro

Anton W Jongejans

Pablo L Garcia Mueller

An antenna capable of generating multiple beams that are close together and have side lobes of low level includes optics comprising a single main reflector and a set of primary sources, each source suitable for generating a beam taken up by the optics that transmits it, or suitable for receiving a beam picked up by the optics of the antenna. The main reflector has an aperture of diameter D as a function of the center wavelength of the frequency band of the beams and the half-power beam width of the beams coming from the main antenna element, and a dimensionless number lying in the range 1.5 to 4. The optics present a profile that is modified relative to conventional optics comprising a parabolic main reflector by a correction that imparts an amplitude and phase distribution that is preferably circularly symmetrical, and compliant with a relationship for enlarging the reflected beams.

Multibeam antenna

A reflector antenna comprising a plurality of plane panels assembled edge to edge to form a non-plane surface constituting an approximation to a reference surface, and a beam-forming device generating a beam-forming function for an array of antenna elements coupled to said panels. The beam-forming function presents at least one surface error correction term to compensate at least in part for the difference between the surface constituted by the assembled panels and the reference surface. In a variant the manner for compensating for the error can be disposed on the panels.

Reflector antenna comprising a plurality of panels

The invention relates to a feed device for a multisource semiactive antenna with multiple beams, including: a) a nonorthogonal beam shaper device (65) splitting Nb beam input signals and combining them to form Na output signals, b) Na amplifier modules (64), c) an orthogonal output power splitter (63) arranged between the Na amplifier modules (64) and Ne radiating elements (61). According to the invention, Nb.ltoreq.Na.ltoreq.Ne, and the orthogonal transfer function of the splitter (63) permits change between, on the one hand, Nb distributions at the input of the splitter (63), in which the amplitude of the Na signals is equal for each of the Nb beams, and in which the phase satisfied the condition of equality of the scalar products, taken in pairs, of the Nb excitation vectors at the input of the splitter (63), and of the scalar products, taken in pairs, of the Nb corresponding output excitation vectors and, on the other hand, Nb predetermined output distributions. Appended FIG. 6.

Feed device for a multisource and multibeam antenna

A circular polarization antenna whose radiation pattern is in the shape of a body of revolution about an axis and has a radiation minimum in the direction of this axis comprises a reflective conductive surface which is essentially in the shape of a body of revolution about the axis. A rectilinear conductive rod extends axially from a first end at the level of and isolated from the conductive surface to a second end and is connected at its first end to an excitation line. A plurality of radiating arms each have a first part extending in an essentially radial plane from the second end of the conductive rod. This first part is electrically connected at its proximal end direct to the conductive rod and is extended at its distal end by a curvilinear rod typically lying on the surface of a sphere centered at the second end and whose general direction is inclined relative to the radial plane.

Circular polarization antenna

There is disclosed a six-port hybrid microwave coupler comprising three inputs and three outputs which are isolated from each other and matched such that a signal applied to any one of the inputs produces signals on all three of the outputs, said signals being orthogonally distributed in phase and uniformly distributed in amplitude. The coupler has a plane configuration of transmission lines with an inner ring comprising three similar segments with the interconnection points of the segments constituting three input or outlet first ports of the coupler. The coupler also has an outer ring comprising three similar segments with the interconnection points of the segments constituting three outlet or input second ports, respectively, of the coupler. The coupler also has three radial branches connecting the interconnection points of the inner ring segments to corresponding interconnection points of the outer ring.

Microwave hybrid coupler having 3.times.n inputs and 3.times.m outputs

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.

Duplexing circularly polarized composite

The apparatus comprises: an array of N radiating elements, subdivided into P subarrays of M elements each, each beam of a specified pattern using a plurality of elements selected from the elements of at least some of the subarrays; a common signal source; power divider means having one input and N outputs to distribute the signal delivered by the source; amplifier means for amplifying said signal; and means for selectively exciting at least some of the elements with the amplified signal at a controlled phase shift so as to obtain the radiation pattern specified for the antenna. According to the invention, the apparatus is provided, between the power divider means and the radiating elements, with: P groups of M phase shifter-and-amplifier modules placed at the output of the power divider means; and P couplers each having M inputs and M outputs, said M inputs being connected to the M corresponding outputs of the associated group of phase shifter-and-amplifier modules, and said M outputs being connected to the M elements of the associated subarray. The phase shifts of the phase shifter-and-amplifier modules are selected in such a manner as to direct the power delivered by the source to those radiating elements that contribute to the specified radiation pattern, and thus to provide distributed amplification of the signal emitted by the source while maintaining an essentially identical and constant load on each amplifier regardless of the changes made to the radiation pattern.

Apparatus for electronically controlling the radiation pattern of an

A multibeam antenna comprising Ne feed elements and emitting Nb beams each generated by a group of Nc elements has a feed device comprising a set of Nc power dividers. These power dividers are unitary orthogonal distribution matrix power dividers of order P, where P is equal to the power of two equal to or immediately higher than the ratio Ne/Nc. The outputs of the dividers are connected to the various elements in such a way that each element of one of the aforementioned groups contributing to a beam is connected to a different power divider and so that adjacent beams share feed elements. A beam forming network has P.times.Nc outputs connected to amplifiers in turn connected to the inputs of the power dividers. This network has Nb inputs. The beam forming network is usually a low-level network. The device finds a specific application in satellite communications.

Multibeam antenna feed device

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).

Large scan antenna with fixed main reflector and fixed feed,

The invention provides an antenna for transmitting or receiving closely spaced multibeams with very low level sidelobes comprising, for each beam feed, a primary feed feeding one or more main elements surrounded by secondary elements some of which are shared between several adjacent beam feed, the power supplied by the primary feed being distributed to the different elements by means of couplers. According to the invention, each shared element is fed by each of the power transmission lines feeding the main element (E1, E'1) of said adjacent beams through a coupler, each transmission line of a secondary radiating element (L2, L'3) comprising at least two couplers (C1, C2) in series.

Power divider for multibeam antennas with shared feed elements

A double grid reflector antenna for radiating different signals having pure linear orthogonal polarization comprises a couple of identical and superposed reflecting grids. One of said grids has been rotated its boresight to disengage its focus from that of the other, and feeds are set in the focal plane of the respective grids. The front grid reflects indifferently either horizontal or vertical polarization, while transmitting the orthogonal polarization to be reflected by the rear grid.

Growing community of inventors

Noordwijk, Netherlands

Antoine G Roederer