Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/02—Waveguide horns
  • H01Q13/025—Multimode horn antennas; Horns using higher mode of propagation
  • H01Q13/0258—Orthomode horns
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P1/00—Auxiliary devices
  • H01P1/20—Frequency-selective devices, e.g. filters
  • H01P1/213—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies
  • H01P1/2138—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies using hollow waveguide filters
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/02—Waveguide horns
  • H01Q13/0241—Waveguide horns radiating a circularly polarised wave
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/02—Waveguide horns
  • H01Q13/0275—Ridged horns
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
  • H01Q15/24—Polarising devices; Polarisation filters 

Definitions

• the present invention relates to a dual-polarization antenna array, in particular each dual-polarization antenna incorporating a polarizer and an evanescent filter.
• Antennas are elements which serve to emit electromagnetic signals into free space, or to receive such signals.
• Simple antennas, such as dipoles, have limited performance in terms of gain and directivity.
• Parabolic antennas allow higher directivity, but are bulky and heavy, which makes their use unsuitable in applications such as satellites for example, when weight and volume must be reduced.
• Antenna arrays are also known which combine several radiating elements (antenna elements) out of phase in order to improve the gain and the directivity.
• the signals received on the various radiating elements, or emitted by these elements, are amplified and out of phase with each other so as to control the shape of the reception and transmission lobes of the network.
• dual-polarization antennae capable of transmitting respectively simultaneously receiving signals with two polarizations.
• the signals transmitted or received by each antenna element are combined, respectively separated, according to their polarization by means of a polarizer.
• the polarizer can also be integrated into the antenna element.
• a dual polarization antenna has two ports for connecting each of the two polarizations separately to or from electronic circuitry or waveguides.
• Such antennas intended to transmit high frequencies, in particular for microwave frequencies, are difficult to design.
• This reduction in the dimension of the elementary antennas and in their spacing creates problems of reflection of a portion of the transmission signal which returns to the antenna or to another port. This results in a loss of efficiency of the transfer of energy emitted, and disturbances of each port by the signals emitted on the other ports.
• a goal when designing such an antenna is also to reduce its weight, in particular in applications for space or aeronautics.
• An object is also to provide an antenna suitable for LHCP and RHCP polarization satellite communications.
• antennas with a modular design which makes it possible to vary the number of elementary antennas as required, without having to review the entire design of the antenna.
• the design is said to be modular when different types of antennas can easily be designed by adding or removing standardized antenna elements during the design of the antenna, without having to revise the entire design of the antenna or the antenna array. waveguides.
• the antenna must also of course have very high efficiency, gain and radiation pattern characteristics that are compatible with the specifications of the application.
• the antenna must be able to be manufactured industrially and without falling within the scope of protection of existing patents.
• An object of the present invention is to provide a dual polarization antenna free from the limitations of known antennas.
• each antenna comprising: at least one first port intended for a first signal with a first polarization; at least a second port for a second signal with a second bias; a polarizer, including a septum for combining the signal on the first port with the signal on the second port; an evanescent filter, preserving the polarizations, one end of which is directly coupled to the polarizer and the other end is directly coupled to the ether, said evanescent filter comprising an internal channel with at least one internal face provided with protuberances in order to adapt the antenna impedance to that of ether.
• Polarization-preserving filters for filtering dual-polarization signals are known as such.
• An example of such a filter is described in EP3147992A1. This filter is however not evanescent, and is not intended to be coupled with ether. Moreover, this filter is not sub-wavelength.
• Waveguide filters in evanescent mode (“evanescent mode filters”) are also known as such. An example of such a filter is described in US7746190B2. However, this filter has a single input and is not intended to be coupled to a downstream polarizer. It is also not intended for downstream ether coupling.
• Evanescent filters are generally composed of a hollow waveguide, which transmits electromagnetic energy between an input port and an output port.
• Evanescent mode filters have the advantage of high selectivity and reduced mass and size. They are usually used between two components, for example between two waveguide sections, but not at the output of a radiating element of an antenna. They are generally not intended for direct coupling with ether.
• the evanescent filter at the output of each antenna of the network makes it possible to adapt the output impedance of the antenna to that of the ether, and thus to maximize the transfer of energy from the antenna to the ether, by limiting the reflection of the transmit signal at the interface between the antenna and the ether.
• This internal channel (that is to say the largest dimension of its cross section) is smaller than the nominal wavelength of the signal for which each antenna is designed.
• This internal channel i.e. the largest dimension of its cross-section
• the diameter of this internal channel is smaller than the smallest wavelength of the signal that each antenna is intended to transmit ("smallest nominal wavelength”).
• Each evanescent filter may comprise several successive protrusions arranged symmetrically in the channel of the waveguide. These protuberances form impedances which, in combination with the capacitances of the channel, form resonance filters.
• Each polarizer can be provided with two ridges, three ridges or a greater number of longitudinal ridges, in addition to the septum.
• These ridges preferably do not extend to the end of the antenna on the ether side.
• each antenna on the ether side is advantageously devoid of septum and ridges, and forms an iris between the polarizer and the ether, in order to match the impedance.
• each antenna on the ether side is advantageously devoid of protuberances, and forms an iris between the polarizer and the ether, in order to match the impedance.
• Each evanescent filter can be provided with several successive protrusions arranged along longitudinal lines, for example along 3 or 4 longitudinal lines in the channel of the filter.
• These protuberances can thus form 3 or 4 discontinuous ridges.
• Each antenna is preferably sub-wavelength (“sub-wavelength”).
• the diameter of the second end of each evanescent filter may be less than the nominal half-wavelength of said signals.
• This type of antenna is particularly compact, but increases the risk of unwanted reflection of the transmitted signal towards another port.
• the evanescent filter allows this reduction in diameter without the risk of unwanted reflection.
• the protuberances of the evanescent filter may each comprise, in the signal transmission direction, a first and a second surface, the first surface, called the inclined surface, being inclined with respect to the second surface.
• each protuberance may be oblique with respect to the plane perpendicular to the longitudinal axis of the antenna.
• each protuberance can form an angle (a) of between 20° and 80°, preferably between 20° and 40° with respect to said internal face.
• the filter channel of each antenna may have a cross section orthogonal to its longitudinal axis of circular, square, rectangular, hexagonal or octagonal shape (neglecting the ridges or protuberances).
• the protuberances can be arranged along three faces of the channel.
• the protrusions can be arranged along four sides of the channel.
• the evanescent filter of each antenna is preferably not flared.
• the section of its internal channel is therefore substantially constant along its longitudinal axis, except for the protuberances which reduce the surface of these sections of the internal canal.
• the antenna array is preferably miniaturized in that the periodicity of the antenna array is less than or equal to 80% of the nominal wavelength of the signals transmitted/received by each antenna.
• the channel of each antenna of the array advantageously has a cross-section which is invariant by rotation of 120° around the longitudinal axis of the channel, the protuberances and/or the longitudinal grooves being spaced apart from each other at 120°.
• the antenna array is advantageously made monolithically.
• Each antenna of the antenna array is advantageously produced by 3D printing of a metal or polymer core, then deposition of a conductive layer at least on the internal faces of the antenna.
• the first port can be provided with a first flange for connection to a first waveguide.
• the second port may be provided with a second flange for connection to a second waveguide.
• the two flanges can be produced by 3D printing.
• Each antenna can be manufactured by a method comprising an additive manufacturing step, for example of the SLM type in which a laser or an electron beam melts or sinters several thin layers of a powdery material. Additive manufacturing can be observed on the antenna thus produced by analyzing the structure of the metal grains thus sintered into a layer.
• an additive manufacturing step for example of the SLM type in which a laser or an electron beam melts or sinters several thin layers of a powdery material. Additive manufacturing can be observed on the antenna thus produced by analyzing the structure of the metal grains thus sintered into a layer.
• Additive metal manufacturing makes it possible to produce complex shapes by limiting or eliminating the assembly steps, which makes it possible to reduce the manufacturing cost.
• Additive manufacturing also makes it possible to manufacture antennas without assembly means between sub-components, or with a reduced number of such assembly means, which also makes it possible to reduce the weight of the antenna.
• SLM selective laser melting
• the first signal can be an RHCP signal.
• the second signal may be an LHCP signal.
• Figure 1 illustrates a sectional view of a dual polarization antenna without evanescent filter
• Figure 2 illustrates a perspective view of a dual polarization antenna and incorporating an evanescent filter
• Figure 3 illustrates a sectional view of the antenna of Figure 2;
• Figure 4 illustrates a perspective view of another dual polarization antenna variant
• Figure 1 schematically illustrates a dual polarization antenna 1 of an antenna array seen in longitudinal section.
• the antenna comprises a core 15 produced by 3D printing and of which at least the internal faces are coated with a metallization 16.
• the core can be made of metal or of an insulating material, for example of polymer or ceramic.
• the metallization 16 can also be provided on the external faces of the antenna.
• the antennas of the array of the present invention being essentially identical, the term “the antenna” is to be understood in the sense of “each antenna of the array of antennas” throughout the present description.
• the antenna is provided with a longitudinal channel 11 leading to an opening 10 at one end of the antenna.
• the cross section of the channel 11 can be for example square, rectangular, round, oval, ellipsoidal, hexagonal, octagonal, pentagonal, etc.
• the channel 11 is shared by a septum 2 into two volumes 12 and 13.
• the first volume 12 leads to a first port 17 intended to receive a first signal P1 with a first polarization.
• the second volume 13 leads to a second port 18 intended to receive a second signal P2 with a second polarization.
• the polarizations can be circular polarizations.
• the second polarization may be orthogonal to the first polarization.
• the first signal may be an LHCP signal.
• the second signal may be an RHCP signal.
• the two signals P1 and P2 combine at the output of the antenna into a single dual-polarized signal emitted into the ether.
• ether is used in the context of the present application to designate the free space outside the antenna, and in which the signals transmitted by the antenna propagate. This means in particular that no device is intended to be coupled to the end of the antenna on the ether side.
• the ether can correspond for example to the space itself when the antenna is mounted on a satellite in orbit, but more generally, the ether designates any free space outside the antenna.
• the ether has its own impedance depending on the characteristics of the space surrounding the antenna.
• a problem with this arrangement relates to the reflection of part of the transmitted signal.
• part Pu of the first signal P1 is diffused towards the ether; another part P12 is reflected at the output of the antenna and returns to the opening 12, see the opening 13.
• the problem is amplified if the antenna is sub-wavelength, that is to say if the diameter of the opening 10 at the output of the antenna 1 is less than half a wavelength of the nominal signal to be transmitted.
• the problem is also magnified if the impedance of the antenna does not match the impedance of the transmission channel through the ether.
• the antennas illustrated schematically in Figures 2 to 4 make it possible to solve or in any case to attenuate this reflection of the signal emitted at the output of the antenna.
• the characteristics of these antennas are identical to those of the antenna discussed above in relation to FIG. 1, and the above description also applies to the antennas of FIGS. 2 to 4; in particular, identical reference numerals designate identical elements.
• the main difference between the embodiments of Figures 2 to 4 and the antenna of Figure 1 concerns the presence of an evanescent filter 4 mounted directly at the output of the polarizer 5 and whose output opening 10 is directly coupled to ether.
• the evanescent filter thus serves directly as a radiating element to emit a signal with double polarization P1+2 combining the polarized signals P1 and P2.
• the antenna thus consists of a polarizer 5 directly coupled to an evanescent filter 4.
• the evanescent filter 4 preferably does not modify the polarizations of the signals through the antenna.
• the polarizations can be circular polarizations.
• the polarizer 5 may conform to the polarizer described in relation to Figure 1; its output is however coupled to the input of the evanescent filter 4, instead of being coupled to the ether.
• the polarizer of the antenna 1 illustrated in Figures 2 to 4 has two input ports 17 and 18, only port 17 being visible in the section of Figure 3.
• Each port can receive a signal P1 or P2 with a first or a second polarization.
• Each port can be connected to a waveguide by means of a flange 170, respectively 180 as illustrated in FIG. 4, or directly connected to an active electronic circuit, for example by means of a coaxial cable.
• the two ports 17, 18 are coupled to volumes 12 respectively 13 of the internal channel 11 of the antenna. These two volumes are separated from each other by a septum 2. As can be seen in FIG. exit 10.
• the polarizer 5 can also be provided with one or more longitudinal grooves 19.
• the use of grooves makes it possible to promote the transmission of a preferred mode of transmission in a compact device.
• the polarizer 5 is provided with two longitudinal grooves 19, in addition to the septum 2.
• the two grooves can be at 120° from each other and from the septum.
• the two ridges can be at 180° from each other and at 90° on either side of the septum.
• the polarizer is provided with three longitudinal grooves 19, in addition to the septum 2. The three grooves can be at 90° to each other and to the septum.
• a number of ridges greater than three can be used.
• the ridges can be straight or twisted.
• the average height of the grooves 19 in the radial direction is lower than that of the septum 2.
• the height of the grooves may decrease from the ports 17, 18 in the direction of the outlet opening 10.
• the polarizer 5 has an outer face whose shape is similar for example to a right prism. Other external shapes, and other sections of channel 11, can be considered.
• the shape of the cross-section of the polarizer, as well as its surface, can evolve gradually from the entrance of the polarizer in the direction of the evanescent filter 4, as seen in Figures 2 to 4.
• the evanescent filter can be seen as an impedance matcher between the polarizer and the ether.
• the diameter of the internal channel of each evanescent filter no longer allows the propagation of the signals as such, that is to say that the waveguide of the filter is below the frequency of cut.
• the protuberances arranged on the internal channel of the filter are thus necessary for the propagation of the signals in the antenna.
• the evanescent filter 4 coupled to the output of the polarizer 5 is provided with protrusions 3 (or teeth).
• channel 11 of antenna 1 comprises several protuberances 3 separated from each other by portions of channel 11.
• the adjacent protuberances 3 are spaced apart longitudinally two by two by a regular or variable pitch p.
• the protrusions 3 can be arranged symmetrically around the longitudinal axis of the evanescent filter.
• the protuberances 3 can be arranged in several rows, for example in the extension of the grooves 19 of the polarizer.
• the protuberances 3 do not extend to the end of the antenna on the ether side.
• the ridges 19 do not extend to the end of the antenna on the ether side.
• the internal channel of the antenna therefore ends on the ether side with a section devoid of ridges, protuberances and septum. This internal channel of the antenna therefore ends on the ether side with an empty section, forming an iris between the polarizer and the ether in order to match the impedance.
• the evanescent filter 4 has an outer face whose shape is similar for example to a cylinder while the channel 11 inside this filter has several protrusions forming filter sections. Other external shapes, and other sections of channel 11, can be considered.
• Antennas 1 with a square, rectangular, hexagonal or octagonal external cross-section can also be used.
• the number of rows of protuberances may be different from three, although three rows is a preferred embodiment in view of the advantages described above.
• the shape of the cross section of the evanescent filter may be different from the shape of the cross section of the associated polarizer 5; for example, in FIGS. 2 and 3, the polarizer 5 has a cross-section at the input which is rectangular or square, this shape changing gradually towards a circular shape to couple directly to an evanescent filter 4 of circular cross-section.
• the geometric shape of the protrusions 3, and their arrangement, can for example be determined by calculation software according to the desired passband.
• the calculated geometric shape can be stored in a computer data carrier.
• the evanescent filter has identical phase performances for the two modes.
• the evanescent filter does not act as a polarizer, ie the phases of the two polarizations are unchanged in the filter.
• the core 15 of the antenna 1 is preferably manufactured by an additive manufacturing process.
• the polarizer 5 and the evanescent filter 4 are preferably made monolithically, their core 15 being manufactured in a single additive printing step.
• additive manufacturing denotes any process for manufacturing the core by adding material, according to the computer data stored on the computer medium and defining the geometric shape of the core.
• the core 15 can for example be manufactured by an additive manufacturing process of the SLM (Selective Laser Melting) type.
• the core 15 can also be manufactured by other additive manufacturing methods, for example by hardening or coagulation of liquid or powder in particular, including without limitation methods based on stereolithography, ink jets (binder jetting) , DED (Direct Energy Deposition), EBFF (Electron Beam Freedom Fabrication), FDM (Fused Deposition Modeling) PFF (Plastic Free Forming), by aerosols, BPM (Ballistic Particle Manufacturing), SLS (Selective Laser Sintering), ALM (Additive Layer Manuafcturing), polyjet, EBM (Electron Beam Melting, light curing, etc.
• the core can for example be made of photopolymer manufactured by several surface layers of liquid polymer hardened by ultraviolet radiation during an additive manufacturing process.
• the core can also be formed from a conductive material, for example a metallic material, by an additive manufacturing process of the SLM type in which a laser or an electron beam melts or sinters several thin layers of a powdery material.
• the metal layer 16 is deposited in the form of a film by electrodeposition or electroplating on the internal faces of the core 15.
• the metallization makes it possible to cover the internal faces of the core with a layer driver.
• the application of the metal layer can be preceded by a step of surface treatment of the inner faces of the core in order to promote the attachment of the metal layer.
• the surface treatment may comprise an increase in the surface roughness, and/or the deposition of an intermediate bonding layer.
• the antenna 1 can be printed with the longitudinal axis z of the channel 11 in a vertical position, or at least substantially vertical.
• the protuberances 3 of the channel 11 can be designed so as to facilitate this additive printing in the vertical position.
• Each protuberance 3 can thus comprise a face which is cantilevered during the manufacture of the filter in the vertical position.
• the face 30 of the protrusions 3 is cantilevered during its additive manufacturing.
• the upper face 31 of the protrusions 3 may extend in a plane substantially perpendicular to the longitudinal axis of the channel 11, that is to say a horizontal plane during manufacture. It is also possible to provide an upper face 31 inclined with respect to this plane.
• the underside 30 cantilevered during printing can be inclined with respect to the horizontal in the vertical manufacturing position.
• the lower face 30 forms an angle ⁇ relative to the horizontal which is between 20° and 80° and preferably between 20° and 40°.
• the geometric configuration of the antenna 1 has the advantage of allowing the production of the core by an additive manufacturing process in a vertical direction opposite to gravity without having recourse, during the core manufacturing process, to any reinforcement intended to prevent part of the core from collapsing under the effect of gravity.
• the angle a of the faces 30 cantilevered relative to the horizontal is sufficient to allow the adhesion of the superimposed layers before their hardening during printing.
• the protuberances 3 illustrated in the examples have polygonal longitudinal sections, for example in the form of a triangle or a trapezium. Other forms of protuberances or teeth can however be imagined, including for example protuberances whose cross-section comprises rounded portions (undulations). [00101]
• the protrusions 3 illustrated in the examples have constant dimensions and in particular depths respectively heights. Slots and/or teeth of variable depth and/or height can however be made. Furthermore, the pitch p between successive slots or teeth can be variable.
• the channel 11 of each antenna 1 of the antenna array has a cross-section orthogonal to the longitudinal axis of the channel which is invariant under rotation of 120° around the longitudinal axis. This is particularly the case when the protrusions are spaced apart from each other by 120° and/or when the polarizer has three longitudinal ridges spaced from each other by 120°.
• the invariance by rotation of 120° of the section of the channel imposes among other restrictions on the geometry of the channel.
• the outer profile of the channel section is thus, for example, circular, triangular, hexagonal, etc.
• the antenna array of the present invention comprises at least two antennas 1, but, in general, is intended to include several tens of antennas 1 arranged in parallel and contiguous manner.
• the periodicity of the array refers to the distance separating the centers of two successive antennas in the array, this distance being typically measured in a plane comprising the apertures of the antennas on the ether side.
• the periodicity of the antenna array is less than or equal to 80% of the nominal wavelength of the signals intended to be emitted/transmitted by each antenna. This value generally constitutes the threshold value below which the reflection of the signals towards the adjacent antennas becomes problematic.

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• Waveguide Aerials (AREA)

Applications Claiming Priority (2)

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• 2021
  • 2021-10-18 FR FR2111032A patent/FR3128321A1/fr active Pending
• 2022
  • 2022-10-18 WO PCT/IB2022/059970 patent/WO2023067482A1/fr not_active Ceased
  • 2022-10-18 CN CN202280069931.XA patent/CN118202517A/zh active Pending
  • 2022-10-18 JP JP2024522480A patent/JP7772929B2/ja active Active
  • 2022-10-18 IL IL311923A patent/IL311923A/en unknown
  • 2022-10-18 EP EP22797504.2A patent/EP4420193A1/de active Pending
  • 2022-10-18 KR KR1020247014750A patent/KR20240073102A/ko active Pending
  • 2022-10-18 CA CA3234116A patent/CA3234116A1/en active Pending
  • 2022-10-18 US US18/701,734 patent/US20250233311A1/en active Pending

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