Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/125—Means for positioning
• • 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
  • H01Q15/02—Refracting or diffracting devices, e.g. lens, prism
  • H01Q15/08—Refracting or diffracting devices, e.g. lens, prism formed of solid dielectric material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
• • 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
  • H01Q15/14—Reflecting surfaces; Equivalent structures
  • H01Q15/16—Reflecting surfaces; Equivalent structures curved in two dimensions, e.g. paraboloidal
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
  • H01Q19/06—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using refracting or diffracting devices, e.g. lens
  • H01Q19/062—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using refracting or diffracting devices, e.g. lens for focusing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/30—Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
  • H01Q25/002—Antennas or antenna systems providing at least two radiating patterns providing at least two patterns of different beamwidth; Variable beamwidth antennas
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/20—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements characterised by the operating wavebands
  • H01Q5/28—Arrangements for establishing polarisation or beam width over two or more different wavebands
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/30—Arrangements for providing operation on different wavebands

Definitions

• An acquisition aiding antenna device and an antenna system for tracking a moving target including such a device for assisting acquisition.
• the invention applies to monitoring stations, tracking, telemetry and flight tests of aircraft or aircraft (aircraft, missiles, drones ...) or in the space domain as the receipt of data from scientific and observation payloads (low-orbiting satellites), orbit control during the launch phase for all types of satellites (LEO, MEO, GEO), for both ground-based and well-grounded antenna systems on warships or civilians, air defense systems, monopulse and multi-band radar systems.
• the main antenna is particularly directive with a fine emission beam, having an opening angle of a few degrees. Given the fineness of its beam, it is difficult to point the main antenna towards the target, especially when it is moving quickly.
• auxiliary antennas intended to be attached to main antennas in a telemetry station.
• This acquisition aid antenna is generally attached to the main antenna and has a much wider lobe than that of the main antenna (between 15 and 30 °, ie up to 20 times that of the main antenna). ).
• the role of the acquisition support antenna is to facilitate rapid acquisition and ensure short-range pursuit. Once the main antenna is properly oriented and the received signal level from the target is sufficient to allow reception by the main antenna, the signal is switched to the main antenna, without loss of pursuit when the target is at a good distance.
• the acquisition aid antenna is also used to retrieve telemetry data in the event of loss of signal by the main antenna.
• the acquisition aid antenna makes it possible to continue tracking a moving target (drone, airplane or missile, for example) when the target is near or moving rapidly.
• Switching from the main antenna to the acquisition aid antenna can also be carried out as a preventive measure when the proximity of the target may cause saturation of the radio frequency equipment.
• Acquisition assistance antennas comprising an antenna source and a small diameter parabolic reflector, the antenna source being disposed at the focus of the reflector.
• a disadvantage of this type of antenna is that, the reflector being of small diameter, the antenna source masks a large part of the reflector. As a result, the acquisition assist antenna exhibits poor performance and a poor reception pattern (having high amplitude side lobes).
• Acquisition assistance antennas are also known comprising a plane array of radiating elements.
• the bandwidth of the network is limited, which can lead to the use of multiple networks in parallel to achieve multi-band reception, and impact the cost and size of the support antenna. acquisition.
• An object of the invention is to propose an antenna system including an antenna for assisting acquisition, which has a small footprint and good performance in terms of performance and quality of the radiation pattern.
• an antenna system for tracking a moving target comprising: a main antenna device comprising:
• a parabolic reflector capable of reflecting a radiation emitted by a target according to a first reception pattern having a main reception lobe having a first opening angle
• a source of main antenna adapted to receive the radiation reflected by the parabolic reflector
• An acquisition antenna device mounted fixedly relative to the main antenna device comprising:
• a multi-band acquisition aid antenna source adapted to receive radiation emitted by a target according to a second reception pattern having a main reception lobe having a second opening angle
• a lens disposed in the main reception lobe of the acquisition aid antenna source for concentrating the radiation received from the target towards the antenna source, so as to receive the radiation emitted by the target according to a third reception pattern having a main reception lobe having a third opening angle smaller than the second opening angle and greater than the first opening angle.
• the proposed acquisition assist antenna device enables target radiation to be focused on the antenna source while having a small footprint.
• the diameter of the device can be in the range of 1.5 to 5 wavelengths, which allows the acquisition antenna device to be placed on the side of the larger main antenna device. diameter.
• the use of a lens disposed in the main receiving lobe of the acquisition-aid antenna source makes it possible to adjust the opening angle of the acquisition-assist antenna device, and provides a good performance while having a small footprint.
• the proposed system makes it possible in particular to use an acquisition antenna source identical to that used for the main antenna device.
• the lens makes it possible to reduce the angle of aperture of the main lobe of the antenna source of assistance with the acquisition of a third angle / second angle quotient between 1 / 6.5 and 1 / 3.25 ,
• the acquisition antenna source comprises a plurality of radiating assemblies, each radiating assembly being adapted to receive radiation in a given frequency band, different from the frequency bands received by the other radiating assemblies, and in which radiating ensemble in the lowest frequency range has a phase center located at the focal point of the lens,
• the other radiating assemblies have phase centers located on an optical axis of the lens while being offset with respect to the focal point of the lens,
• the radiating elements are arranged such that the higher the frequency range of a radiating element, the closer the phase center of the radiating element is to the lens,
• the lens is configured to transform a quasi-plane wave received from the target into a spherical wave, the spherical wave being emitted towards the acquisition antenna source,
• the lens is formed in at least one block of material, the material having a density of between 1.05 and 1.15, and a relative permittivity (or dielectric constant) of between 2.5 and 2.7,
• the material forming the lens is a polymeric material, preferably a polystyrene-based material,
• the main antenna source and the acquisition antenna source are identical to each other.
• FIGS. 1 and 2 schematically represent an antenna system for tracking a moving target, according to an embodiment of the invention
• FIG. 3 schematically represents, in longitudinal section, an antenna device for assisting the acquisition
• FIG. 4 schematically represents, in longitudinal section, a lens of the device for assisting acquisition
• the antenna system 1 shown comprises a main antenna device 2 and an associated auxiliary antenna device 3.
• the main antenna device 2 comprises a main antenna source 4 and a parabolic reflector 5.
• the main antenna source 4 is positioned at the focus of the parabolic reflector 5.
• the main antenna source 4 is held in this position by a support 6 for fixing the main antenna source 4 on the parabolic reflector 5.
• the main antenna source 4 may be a multiband source, for example a multiband source as described in the document FR 3 007 215. Such a source is able to transmit and / or receive telemetry signals selectively in each of the bands. frequency L (1 GHz to 2GHz), S (2GHz to 4GHz) and C (4 GHz to 8GHz).
• the main antenna source 4 is adapted to illuminate the parabolic reflector 5 with an opening angle at -10 dB approximately 70 degrees around the main receiving axis X 1 of the source 4.
• the source main antenna 4 substantially illuminates the entire reflective surface of the parabolic reflector 5.
• the parabolic reflector 5 is adapted to reflect radiation emitted by a target towards the source 4 with an opening angle at -10dB ⁇ of between 2 and 8 degrees.
• the auxiliary antenna device 3 (referred to as an "acquisition antenna device") is arranged adjacent to the main antenna device 2.
• the acquisition aid antenna device 3 is mounted fixed on the main antenna device 2. Thus, when tracking a moving target, the two devices 2 and 3 are driven together in an identical displacement.
• the acquisition aid antenna device 3 comprises an acquisition aid antenna source 7, a lens holder 8 and a lens 9.
• the antenna system 1 also comprises a support arm 10 connecting the acquisition aid antenna device 3 to the main antenna device 2.
• the support arm 10 is fixed on the one hand to the parabolic reflector 5 of the main antenna device 2 and on the other hand to the casing of the acquisition aid antenna source 7.
• the support arm 10 holds the acquisition aid antenna device 3 in a fixed position relative to the main antenna device 2.
• the acquisition aid antenna source 7 is identical to the main antenna source 4.
• the source of acquisition aid has the same characteristics of frequency bands, polarization and diagrams (sum and difference) as the main antenna source.
• the source An acquisition support antenna can be used temporarily as the main antenna source.
• the acquisition assist antenna device is illustrated more precisely in FIG. 3.
• the acquisition aid antenna source 7 has a main reception axis X2, parallel to the main reception axis X1 of the main antenna source.
• the acquisition aid antenna source 7 comprises a plurality of radiating assemblies 1 1 to 16 capable of generating radiation respectively in the frequency bands C, S and L. Each radiating assembly 1 1 to 16 is clean. receiving radiation according to a first reception pattern having a reception main lobe oriented along the main reception axis X2.
• the radiating assemblies comprise:
• a first delta radiating assembly 1 1 able to receive a delta radiation in the first frequency band L
• a first sigma radiating assembly 12 capable of receiving a sigma radiation in the first frequency band L
• a second delta radiating assembly 13 able to receive a delta radiation in the second frequency band S
• a second sigma radiating assembly 14 able to receive a sigma radiation in the second frequency band S
• a third delta radiating assembly 15 capable of receiving delta radiation in the third frequency band C
• a third sigma radiating assembly 16 capable of receiving a sigma radiation in the third frequency band C.
• the main reception lobe has an opening angle ⁇ .
• An aperture angle ⁇ denotes the aperture angle of the acquisition assist antenna source 7 alone, without the lens 9.
• the aperture angle ⁇ is about 130 degrees at - 10dB.
• the lens 9 is positioned on the main reception axis X2 of the acquisition aid antenna source 7, the optical axis of the lens 9 coinciding with the main receiving axis of the source 7.
• the lens 9 is disposed with respect to the acquisition aid antenna source 7 so that the source receives all the radiation transmitted by the lens.
• the lens 9 is a convergent lens having a first convex surface 17 (also called “inner surface”) and a second convex surface 18 (also called “outer surface”), opposite to the first convex surface 17.
• the first convex surface 17 is directed towards the source 7.
• the second convex surface 18 is directed towards a target to be detected.
• the lens 9 is configured to focus the radiation emitted by the target to the acquisition assist antenna source 7, so as to obtain a reception pattern of the acquisition assist antenna device having a receiving main lobe having an opening angle ⁇ less than the opening angle ⁇ .
• the lens 9 is sized to reduce the opening angle of the main lobe with a ⁇ / ⁇ quotient between 1 / 6.5 and 1 / 3.25.
• the angle ⁇ is thus between 20 and 40 degrees at -10 dB (depending on the frequency band considered).
• the lens holder 8 makes it possible to mount the fixed lens 9 with respect to the acquisition-aid antenna source 7.
• the lens holder 8 has a generally tubular shape.
• the lens holder 8 comprises a wall 19 of generally cylindrical shape of revolution defining a first opening 21 and a second opening 22.
• the lens support 8 is fixed on the one hand to the source of acquisition aid 7, the source extending through the first opening 21, and secondly to the lens 9, the lens 9 obstructing the second opening 22.
• the lens 9 has a point focus.
• the assembly radiating in the lowest frequency range (in this case, the assembly 12 radiating in the band L) has its phase center located at the focus of the lens 9.
• the radiating assemblies in the other frequency ranges (in this case, the sets 14 and 16 radiating in the strips S and C) have phase centers located on the optical axis of the lens 9 being offset from the focal point of the lens 9.
• the radiating assemblies 12, 14 and 16 are arranged so that the higher the frequency range of a radiating assembly is high, the phase center of the radiating assembly is away from the focus of the lens 9 and close to the first surface 17 of the lens 9.
• the phase centers of the radiating elements in the ranges of the highest frequency (in this case, the sets 14 and 16 radiating in the bands S and C) are located between the focus of the lens 9 and the lens 9.
• the radiating assemblies 12, 14 and 16 By controlling the position of the phase centers of the radiating assemblies 12, 14 and 16 with respect to the focal point of the lens 9, it is possible to adjust the opening angle ⁇ for each of the frequency ranges L, S and C , on a bandwidth of 2 octaves.
• the radiating assemblies 12, 14 and 16 may be arranged along the optical axis of the lens so as to minimize the variation of the opening angle ⁇ as a function of the reception frequency range L, S and C.
• the lens 9 is dimensioned to transform a quasi-plane wave received from the target into a spherical wave, the spherical wave being emitted towards the antenna source 7, in the lowest frequency range (in this case, the band L).
• the lens 9 can be formed by machining in one or more blocks of material.
• the material used preferably has a density of between 1.05 and 1.15, and a relative permittivity of between 2.5 and 2.7.
• the material forming the lens 9 is a dielectric material, such as a polymeric material, having low dielectric losses (loss tangent ⁇ 0.0007 to 10 GHz) in the reception frequency ranges of the light source. acquisition and a refractive index greater than 1.5.
• the polymeric material may be a polystyrene and hydrocarbon material.
• An example of a suitable material is a material sold under the name Rexolite® by San Diego Plastics, Inc., obtained by crosslinking a polystyrene with a divinylbenzene.
• the lens 9 is formed of two pieces of material 23 and 24.
• the two pieces 23 and 24 are fixed to one another by means of screws 25. It is thus it is possible to manufacture each part 23, 24 independently of the other, and in particular to machine each convex surface 17 and 18 separately.
• Figure 5 schematically shows the parameterization of the lens for calculating the equations of the surfaces 17 and 18 of the lens.
• L Q distance between the focus 0 1 and the first convex surface 17
• L 0 ' distance between the point 0 2 and the first convex surface 17
• T thickness of the lens
• ⁇ ⁇ maximum angle of focus by the ray lens at point 0 2 ,
• T ldB level of the field of the incident wave at the edge of the lens
• T 2dB level of the field of the refracted wave at the edge of the lens
• n index of the material forming the lens
• a point M 1 of coordinates x, z ⁇ ), as a point of intersection of a radius with the first surface 17 of the lens, and a point M 2 , of coordinates (x 2 , z 2 ), a point of intersection of the same radius with the second surface 18 of the lens.
• the resolution of the differential equation can be achieved by a Runge Kutta method, order 4.
• the resolution of the differential equation leads to obtaining two series of points M 1 and M 2 (each point being defined by its coordinates (x z and (3 ⁇ 4, z 2 )) of the first surface 17 and the second surface 18 of the lens.
• the surface equation can be calculated as a polynomial by interpolation of the series of points.
• the lens is thus specifically shaped to have a focal length adjusted to the different phase centers of each sub-band of the source, which allows to achieve excellent performance at even the lowest frequencies.
• the diameter of the acquisition aid antenna is thus minimized, as is its weight. For example, a lens 30 to 40 centimeters in diameter can simultaneously cover the L, S and C bands of the telemetry with the correct opening angle and reduced side lobes.
• the use of a lens disposed in the receiving beam of the acquisition-aid antenna source makes it possible to adjust the opening angle of the acquisition-aid antenna device, and allows to obtain a good performance while having a small footprint.
• the multi-band source based on differentiated radiating elements is a solution that confers good merit factors on the main antenna.
• the proposed system makes it possible to use an acquisition antenna source identical to the main antenna source. Reusing the main antenna source for acquisition simplifies the design and maintenance of the antenna system, although it is still possible to use different sources.
• the topology of the tracking device is thus identical for the two antennas.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Aerials With Secondary Devices (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)

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• 2015
  • 2015-10-22 FR FR1560104A patent/FR3042917B1/fr active Active
• 2016
  • 2016-10-21 WO PCT/EP2016/075454 patent/WO2017068155A1/fr active Application Filing
  • 2016-10-21 EP EP16784538.7A patent/EP3365943B1/de active Active
  • 2016-10-21 US US15/769,574 patent/US10700407B2/en active Active
• 2018
  • 2018-04-22 IL IL258834A patent/IL258834B/en active IP Right Grant

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