Classifications

• • 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
  • H01Q19/10—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 reflecting surfaces
  • H01Q19/12—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 reflecting surfaces wherein the surfaces are concave
  • H01Q19/13—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 reflecting surfaces wherein the surfaces are concave the primary radiating source being a single radiating element, e.g. a dipole, a slot, a waveguide termination
  • H01Q19/138—Parallel-plate feeds, e.g. pill-box, cheese aerials
• • 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
  • H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/22—Longitudinal slot in boundary wall of waveguide or transmission line
• • 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
  • H01Q19/10—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 reflecting surfaces
  • H01Q19/12—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 reflecting surfaces wherein the surfaces are concave
  • H01Q19/17—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 reflecting surfaces wherein the surfaces are concave the primary radiating source comprising two or more radiating elements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/0006—Particular feeding systems
  • H01Q21/0037—Particular feeding systems linear waveguide fed arrays
  • H01Q21/0043—Slotted waveguides
  • H01Q21/005—Slotted waveguides arrays
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
  • H01Q21/061—Two dimensional planar arrays
  • H01Q21/064—Two dimensional planar arrays using horn or slot aerials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
  • H01Q3/12—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems
  • H01Q3/16—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems for varying relative position of primary active element and a reflecting device
  • H01Q3/18—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems for varying relative position of primary active element and a reflecting device wherein the primary active element is movable and the reflecting device is fixed

Definitions

• a multilayer antenna with parallel planes, of the pillbox type, and corresponding antenna system is provided.
• the field of the invention is that of multilayer antennas with parallel planes, also called “pillbox antennas” or “cheese antennas” in English.
• the invention has many applications, such as for example: automotive radars, communications between mobile platforms (cars, trucks, trains, boats, etc.) and satellites, communications between mobile platforms (high altitude platforms
• High Altitude Platform (HAP), aircraft, etc.) and ground (for example in the Ku, Ka and Q bands), terrestrial wireless communications (inside or outside buildings) with multiple beam capabilities, beam shaping and beam reconfiguration.
• Parallel Plate Waveguide and single layer (also called monolayer systems) antenna systems
• the energy provided by a source is confined between two metal plates located on each side of the board. another of a substrate layer, to then be guided to a radiating part also included in this layer.
• This radiating part is generally composed of integrated slotted waveguides ("Slotted waveguide array” in English) for example made in SIW technology ("Substrate Integrated Waveguides” in English) or leaky wave structures.
• Conductive vertical walls, connecting the two metal plates, which behave as a mirror for the energy of the wave, make it possible to reflect or direct the energy. These vertical walls generally have a parabolic profile in order to collimate the energy coming from the source. But to avoid a backscattering towards the source, it is necessary to use a solution based on double reflector or off-center configuration, or a double layer structure.
• the source and the radiating part are in two different layers, connected by a 180 ° parallel plate bend plate of often parabolic profile.
• Such multilayer antennas with parallel planes are described for example in the two following scientific documents:
• the main advantage of these antennas is their modularity. Indeed, three parts corresponding to different functions can be distinguished: a supply part (source), a radiating part and a guide part.
• the latter makes it possible to guide the energy of the wave generated by the source, from the supply portion to the radiating part, through the superimposed layers of the parallel plan guide type.
• the guide portion comprises transition means between these layers, comprising a reflector cooperating with a slot.
• the goal of the next generation of radar for automotive applications is to improve safety along the roads, by controlling and responding effectively to different scenarios at the front of the car (accident, vehicles too close to each other). others, ).
• two areas of action are particularly well defined: a short radar range (SRR) and a long radar range (LRR). , extending respectively from 0 to 30 m and from 30 to 200 m (typical values) from the front of the vehicle, which is the classic position of an onboard detection antenna.
• a first well known technique is based on the use of diélecriques lenses.
• Commercial solutions already exist. These solutions are very attractive but remain cumbersome.
• a second well known technique consists in using Rotman lenses which are quasi-optical planar systems having three focal points, as described for example in the following scientific document: W. Rotman, R. F. Turner,
• a major disadvantage of this second technique is the large size of the complete antenna system and its low modularity, because all the parts (power supply, guide portion and radiating portion) are made on the same substrate.
• the Rotman lens has large dimensions that can not reduce the overall size of the antenna.
• This structure is also limited in the number of input beams to perform a full scan.
• a third known technique relates to a parallel plan ("pillbox") and double layer antenna, as presented in the following scientific document: T. Teshirogi, Y. Kawahara, A. Yamamoto, Y. Sekine, N. Baba, M. Kobayashi, "Dielectric Slab Based Leaky-Wave Antennas for Millimeter-Wave Applications,” IEEE Antennas and Propagation Society International Symposium, 2001, Vol. 1, pp.
• Figures 1 and 2 show views, in perspective and in section respectively, of an antenna according to this third known technique. It comprises a low layer 5 and a high layer 6.
• the low layer 5 is a parallel plan structure comprising two metal plates 8, 9.
• the high layer 6 is also a parallel plan structure comprising two metal plates 9, 4, including one (that referenced 9) is common to both layers and two parallel plan structures.
• the two layers 5, 6 are connected by transition means comprising a reflector 2 (180 ° parallel plate bend plate) of parabolic profile and a single slot 7 extending along and along the entire length of the parabolic reflector 2.
• the feed portion comprising a single sectorial horn 1.
• In the upper layer 6 is placed the radiating portion 3.
• the transition means allow the transfer of energy between the low layer 5 and the high layer 6 (that is to say from the horn 1 to the radiating portion 3), the wavefront incident on the parabolic reflector being a cylindrical wavefront.
• the main disadvantages of this third known technique lie in the fact that the transition means comprise a single slot, which does not allow an optimal energy transfer (due to the existence of resonance phenomena in a single slot) and is effective only in a narrow angular range. The resolution is not optimal.
• the combined use (in the transition means) of a parabolic reflector and a single slot does not make it possible, according to the patent document WO91 / 17586, to obtain a perfectly plane wavefront in the high layer (after reflection on the reflector) if the incident wavefront of the lower layer is a cylindrical (or more generally non-plane) wavefront.
• this third known technique does not allow to use several sources of excitation since the horn extends directly to the edge of the reflector parabolic (sectoral cornet). No beam reconfiguration or beam scanning is therefore possible.
• a fourth known technique is a variant of the aforementioned third known technique. It is described in the following scientific document: V. Mazzola, J. E. Becker, "Coupler-Type Bend for Pillbox Antennas", IEEE Transactions on
• the single slot (included in the transition means between the two layers) is replaced by a plurality of circular openings, distributed in a triangular mesh (that is to say a mesh whose basic pattern is a triangle) that extends all along the reflector.
• a triangular mesh that is to say a mesh whose basic pattern is a triangle
• the coupling performed by the transiton means is improved, the operating frequency band is wider and the angular range is wider also. It operates in the plane E (electric field parallel to the metal plates forming the parallel planes of the two layers).
• a disadvantage of this fourth known technique is that it can only operate with a single polarization (horizontal polarization: TE mode in waveguide with parallel planes (PPW, for "parallel flat waveguide” in English). therefore not work in double polarization.
• Another disadvantage of the fourth known technique is that the increase of the efficiency of the transition is achieved to the detriment of an increase of the coupling region (number and size of the circular openings included in the triangular mesh), and therefore to the final an increase in the size and cost of the antenna. 3. OBJECTIVES OF THE INVENTION
• the invention in at least one embodiment, is intended in particular to provide a multilayer antenna with parallel planes ("pillbox") not having the disadvantages of the known technical solutions discussed above.
• An object in at least one embodiment of the invention is to provide an antenna comprising transition means between two adjacent layers (called low and high layers, for example), allowing optimal and efficient energy transfer. in a wide angular range and frequency, even if these transition means comprise a non-planar shape reflector (parabolic for example). It is therefore desired to obtain a perfectly plane wavefront in the high layer (after reflecting on the reflector) even if the incident wavefront of the lower layer is a non-plane wavefront (for example cylindrical).
• Another object of at least one embodiment of the invention is to provide an antenna that can operate in double polarization or circular polarization.
• Another objective, of at least one embodiment of the invention is to provide an antenna making it possible to use several excitation sources, and therefore whose beam is reconfigurable (multi-beam, beam misalignment (x) , beam (x) with variable directivity).
• Another objective, of at least one embodiment of the invention, is to provide a compact and low weight antenna.
• Another objective, of at least one embodiment of the invention is to provide a simple antenna to implement and inexpensive.
• a multilayer antenna comprising: a power supply portion generating a wave; - a radiant part; a guide portion for guiding said wave from the supply portion to the radiating portion, said guide portion comprising:
• transition means between said adjacent layers comprising a reflector cooperating with a slot coupling means, said antenna being such that, for at least one pair of adjacent layers for which the guide portion comprises a a non-planar shaped reflector, the slot coupling means comprises a plurality of slots, each slot comprising a main body having an elongate shape in at least one axis, said plurality of slots being arranged on at least one row and together forming a pattern which extends along the reflector and has a shape depending on the shape of the reflector.
• the invention is based on a completely new and inventive approach of retaining a non-planar shape reflector (for example of the type parabolic) and replace, in the transition means between the two layers, the single slot of the third known solution: not by a plurality of circular openings distributed in a triangular mesh that extends all along the reflector (as in the fourth known technique), but by a plurality of slots (see below the description of FIGS. 17A to 17E for the definition of the term "slot" in the context of the present invention, as well as for a few non-limiting examples of slots) .
• the resonance effects appearing in a continuous slot are reduced.
• the transfer of energy between two successive layers is then improved, and this in a wide angular range and a wide frequency band. In other words, an antenna having an optimized efficiency in terms of power transfer is obtained.
• the combined use (in the transition means) of a non-planar shaped reflector (the incident wavefront of the lower layer is therefore a non-plane wavefront) and a plurality of slots allows to obtain a perfectly plane wavefront in the high layer (after reflection on the reflector).
• the use of a plurality of slots provides an antenna capable of operating in dual polarization. This also provides an antenna that can use multiple excitation sources, and thus whose beam is reconfigurable.
• said plurality of slots is arranged on a single row.
• each slot comprises a main body having an elongated shape along at least one axis substantially parallel or perpendicular to the reflector.
• At least some slots comprise a main body having an elongate shape along a single axis.
• the antenna can operate in single polarization.
• FIGS. 17A to 17C illustrated in detail below, illustrate some nonlimiting examples of slots that can be used in this first embodiment of the invention.
• At least some slots comprise a main body having a cross shape, said main body comprising a first leg having an elongate shape along a first axis and a second leg having an elongate shape along a second axis substantially perpendicular to the first axis.
• the plurality of cross slots can be replaced by a set of first slots comprising a main body having an elongate shape along a first axis, and a set of seconds. slots comprising a main body having an elongate shape along a second axis substantially perpendicular to the first axis.
• the shape of the pattern that together form said plurality of slots has a shape substantially identical to that of the reflector.
• the reflector has either a conventional shape (parabola, ellipse, hyperbola, circle), or any other form adapted to a specific need.
• each slot of said plurality of slots has a length between 0.25 * ⁇ d and 0.5 * ⁇ d, and a width between 0.1 * ⁇ d and 0.2 * ⁇ d, with ⁇ d the wavelength in the superposed layers of guide type with parallel planes, at the operating frequency of the antenna.
• each slot of said plurality of slots is at a distance, relative to the reflector, of between 0.3 * ⁇ d and 0.5 * ⁇ d, with ⁇ d the wavelength in the guide type superimposed layers. with parallel planes at the frequency of operation of the antenna.
• the distance of each slot relative to the reflector is a parameter on which it is possible to play, for each slot, to easily optimize the efficiency of the transition in which the slots participate.
• the gap between two adjacent slots of said plurality of slots is between 0.02 * ⁇ d and 0.1 * ⁇ d, with ⁇ d the wavelength in the layers superimposed guide type plan parallel to the operating frequency of the antenna.
• the distance between two adjacent slots is a parameter on which it is possible to play, for each slot, to easily optimize the efficiency of the transition in which the slots participate.
• said feed portion comprises at least two sources intertwined with each other physically or electrically.
• said supply portion comprises at least one source and a first means of mechanical displacement of said at least one source, in a plane parallel to the superimposed layers of guide type with parallel planes.
• said feed portion comprises at least two sources and means for selectively feeding said at least two sources.
• an antenna system comprising a multilayer antenna according to one of the aforementioned embodiments, and a second means of mechanical displacement of said antenna.
• the multilayer antenna radiates substantially in a plane (see Figure 18), that the second moving means can move.
• an antenna system comprising a multilayer antenna according to one of the aforementioned embodiments (that is to say comprising: a first power supply portion generating a first wave, a radiating portion, and a guide portion for guiding said first wave from the first supply portion to the radiating portion, said guide portion comprising at least two parallel plane guide type superimposed layers, and, for each pair of adjacent layers, first transition means between said adjacent layers, comprising a first reflector cooperating with a first slot coupling means).
• the antenna system includes a second power supply generating a second wave.
• Said guide part also makes it possible to guide said second wave from the second feed portion to the radiating portion, said guide portion further comprising, for each pair of adjacent layers, second transition means between said adjacent layers, comprising a second reflector cooperating with a second slot coupling means, said second transition means being offset by 90 ° with respect to said first transition means.
• the first slot coupling means comprises a plurality of first slots, each first slot having an elongate shape along at least one axis, said plurality first slots being arranged on at least one row and together forming a pattern which extends along the first reflector and has a shape depending on the shape of the first reflector.
• the second slot coupling means comprises a plurality of second slots, each second slot having an elongate shape in at least one axis, said plurality second slots being arranged on at least one row and together forming a pattern which extends along the second reflector and has a shape depending on the shape of the second reflector.
• Beam shape change and / or beam sweep in a simple, reliable, compact and inexpensive way.
• FIGS. 1 and 2 show views, in perspective and in section respectively, of an antenna according to the known technique of Teshirogi et al.
• Figures 3 and 4 show views, in perspective and in section respectively, of a two-layer antenna according to a particular embodiment of the invention
• Figure 5 is a schematic perspective view of a physical interleaving of sources included in the power supply part, according to a particular embodiment of the invention
• Figure 6 illustrates different possible profiles for the reflector included in the transition means between two adjacent layers
• Figure 7 is a schematic view of a plurality of slots cooperating with a parabolic reflector, in a first particular embodiment of the transition means between two adjacent layers, for operation in single polarization
• Figure 8 is a schematic view of a plurality of slots cooperating with a parabolic reflector, in a second particular embodiment of the transition means between two adjacent layers, for dual polarization operation
• Figure 9 is a sectional view of a two-layer antenna according to a particular embodiment of the invention, showing a set of physically interleaved sources
• Figure 10 shows four radiation patterns obtained with the antenna of Figure 9, for four different power configurations (each power configuration corresponding to
• FIG. 11 shows a partial perspective view of a two-layer antenna according to a particular embodiment of the invention, comprising first means of reconfiguration of the radiating part, based on the use of diodes or short loads; circulated (shunts);
• FIG. 12 shows a partial perspective view of a two-layer antenna according to a particular embodiment of the invention, comprising second means for reconfiguring the radiating part, based on the use of two sets of slots in the radiant parts;
• Figure 13 is a top view of an antenna system according to a particular embodiment of the invention;
• Figure 14 is a perspective view of a three-layer antenna according to a first particular embodiment of the invention;
• Figure 15 is a perspective view of a three-layer antenna according to a second particular embodiment of the invention;
• FIG. 16 is a perspective view of a three-layer antenna according to a third particular embodiment of the invention.
• FIGS. 17D and 17E illustrate some nonlimiting examples of coupling slots that can be used in an antenna according to the invention; and
• FIG. 18 illustrates the notion of the main radiation plane of the antenna of FIGS. 3 and 4, as well as the notions of beam shape change and beam sweep. 6.
• a two-layer antenna 30 according to a particular embodiment of the invention is now presented.
• Such an antenna can for example be used in radars, for automotive applications.
• the antenna 30 comprises a guide portion comprising two parallel planar layers having a metal plate M.2 in common. More specifically, the guide portion comprises: a first parallel plane layer, itself comprising two metal plates M.sub.1, M.sub.2 located on either side of a Sub.l dielectric substrate layer; a second layer with parallel planes, itself comprising two metal plates M.2, M.3 located on either side of a Sub.2 dielectric substrate layer.
• h2 (V ⁇ r2 / V ⁇ r i) * hl (equation 1)
• h2 and h1 are respectively the heights of the two substrate layers Sub.2 and Sub.l
• ⁇ rl and ⁇ r 2 are respectively the permitivities of the two substrate layers Sub.l and Sub.2.
• h1 h2
• ⁇ r1 ⁇ r2 with ( ⁇ r1 , ⁇ r2 ⁇ 1).
• the two substrate layers are coupled by an optical transition means comprising a parabolic reflector R1 and a plurality of coupling slots 10 made in the common metal plate M.2.
• the parabolic reflector R1 extends from the metal plate M.sub.1 to the metal plate M.sub.3.
• Other reflector profiles may be used (see below the description of FIG. 6).
• each coupling slot 10 has a rectangular shape and extends along an axis substantially parallel to the reflector.
• the plurality of coupling slots 10 are arranged on a row and together form a parabolic pattern that extends along the parabolic reflector.
• the pattern formed together by the coupling slots is for example the locus formed by the geometric centers of the slots (as for example that given by the equation number 2 given below, this equation is not limiting).
• Other forms of coupling slots can of course be used without departing from the scope of the present invention.
• FIGS. 17D and 17E some nonlimiting examples of coupling slots that can be used in an antenna according to the invention.
• Figure 17A shows a rectangular slot 170 (i.e. a slot comprising a main body having a rectangular shape and thus elongated along an axis).
• Figure 17B shows a slot 171 comprising a main body having an elongate shape along an axis. This slot 171 differs from that of Figure 17A in that its ends are rounded.
• Fig. 17C shows an H slot (also referred to as a dog bone slit 172 comprising a main body 172a having an elongated shape along an axis, and two split ends 172b, 172c. split allows to reduce the physical length of the slot (compactness objective of the antenna) but not its electrical length. Typically, the length If of each split end 172b, 172c is much greater than the length Lf of the main body 172a (for example in a ratio 3 to 4). In a variant (not shown), the split ends of the H slot are rounded.
• FIG. 17D shows a simple cross slot 173. It comprises a main body comprising a first branch 173a, 173b having an elongated shape along a first axis and a second branch 173c, 173d having an elongate shape along a second axis substantially perpendicular to the first axis.
• the ends of the simple cross slot are rounded.
• FIG. 17E shows a Jerusalem cross slot 174. It comprises a main body comprising a first branch 174a, 174b having an elongated shape along a first axis and a second branch 174c, 174d having an elongate shape along a second axis substantially perpendicular to the first axis.
• Each end 174e, 174f, 174g, 174h of branch is split. This makes it possible to reduce the physical length of the slot (objective of compactness of the antenna) but not its electrical length. Typically, the length of each split end is much greater than the length of the leg (of the main body) at the end of which is is located (for example in a ratio 3 to 4). In a variant (not shown), the ends of the Jerusalem cross slot are rounded.
• the cross slots allow operation of the dual polarization antenna.
• the antenna 30 also comprises a feed portion comprising a source Sl placed in the Sub.l substrate layer.
• a source Sl placed in the Sub.l substrate layer.
• the antenna also comprises a radiating part which is formed on the Sub.2 substrate layer and which comprises a plurality of radiating slots 1 1 made in the upper metal plate M.3.
• FIGS 3 and 4 there is also shown a BFN substrate (for "Beam Forming Network" in English).
• This BFN substrate allows the shaping of the beam by excitation or not of the source or sources, for example by means of active components (diodes or EMS components for example).
• this antenna is as follows: the energy of the wave generated by the source S1 is guided by the first layer with parallel planes (metal plates M.sub.1, M.2 and Sub substrate layer 1). Thanks to the optical transition means (reflector R1 and plurality of coupling slots 10), this energy is transferred to the second layer with parallel planes (metal plates M.2, M.3 and Sub.2 substrate layer), where finally it is radiated by the radiating part (plurality of radiating slots 11).
• Figure 18 illustrates the main radiation of the antenna 30 of Figures 3 and 4.
• the mode used is the TEM mode, in which the electric field is oriented along the Z axis.
• the main radiation pattern comprises for example a main lobe (this is particularly the case if a single source is powered).
• the antenna it is possible to: change the shape of the main radiation pattern (by changing the number of powered sources). To illustrate this change of shape in FIG. 18, two possible beams have been represented, one narrow 181a,
• the feeding part is now presented in more detail. It is located at the focal plane F (or in the vicinity of this focal plane) of the reflector Rl of the transition means. It comprises either a single source (case of the source Sl in FIG. 3) or several sources.
• the source or sources can generate a TEM wave (for "Transverse Electromagnetic” in English), a wave TE (for "Transverse Electric” in English) or both.
• the TEM wave has an electric field oriented along the Z axis, while the TE wave has an electric field along the Y axis.
• the TEM mode is more particularly described below.
• the elementary source (s) are sectorial horns H ("integrated H-plane sectoral horn" in English).
• H integrated H-plane sectoral horn
• Such a horn shape is particularly advantageous in the case where several sources are used to generate one or more beams and thus be able to perform the reconfiguration of beams.
• other well-known source shapes can be used (monopole networks, interleaved Perot-Fabry sources, etc.).
• an advantageous solution in terms of size and efficiency of illumination of the reflector R1 consists of physically interleaving sources.
• Figure 9 is a sectional view of a two-layer antenna according to a particular embodiment of the invention, showing a set of physically interlaced sources on two levels.
• nine sources are used. They are distributed as follows (in the order from left to right, in FIG. 9): on the first level, the sources S9, S7, S1, S3 and S5; and on the second level, sources S8, S6, S2 and S4. Compared to the sources of the first level, the sources of the second level are shifted to the right by half a length of horn opening.
• FIG. 6 shows different possible profiles for the reflector R1 included in the transition means between the first layer with parallel planes (metal plates M.sub.1, M.sub.2 and substrate layer Sub.1) and the second layer with parallel planes ( metal plates M.2, M.3 and Sub.2 substrate layer).
• These different profiles are a hyperbolic profile 63, an elliptical profile 62, a parabolic profile 61 and a circular profile 64.
• Other optimized arbitrary shapes can obviously be used.
• the profile of the reflector depends on the wave profile that must arrive in the second layer with parallel planes, according to the optical laws.
• the profile most often used for the "pillbox" type antennas is the parabolic profile 61. In fact, in this case, the energy coming from the focal point F2 will be reflected, in the second layer with parallel planes, as a planar wave. and concentrated and directed to the radiating portion which is usually a planar network.
• the pattern that together form the coupling slots has a shape identical (or substantially identical) to that of the reflector along which they are located.
• Figure 7 is a schematic view of a plurality of coupling slots 10 cooperating with a parabolic reflector R1, in a first particular embodiment of the transition means between two adjacent layers, for operation in single polarization.
• each coupling slot 10 has a rectangular shape along an axis substantially parallel to the reflector.
• the plurality of slots coupling 10 are arranged on a row and together form a parabolic pattern that extends along the parabolic reflector.
• Other non-rectangular slot shapes may be used (see the description of Figs. 17A-17C).
• optical transition means in terms of energy transfer to the second layer with parallel planes, and cancellation of the reflected wave coming back from the reflector towards the source
• performance of these optical transition means can be increased by varying the dimensions ( length 1 S1 and width w sl ) and the position (r sl ) of each i th coupling slot.
• the i th coupling slot occupies a position of which one of the cylindrical coordinates is defined by the following relation:
• ⁇ d is the wavelength in the dielectric (that is, in the superimposed layers of the guide type with parallel planes) at the operating frequency of the antenna.
• the number of slots is chosen such that the space ⁇ sl between two adjacent slots obeys the condition: 0.02 * ⁇ d ⁇ sl ⁇ 0.1 * ⁇ d .
• the symmetry of the structure along the xz plane is also preserved.
• a non-symmetrical distribution of the slots is also possible depending on the type of beam to be radiated by the antenna.
• Figure 8 is a schematic view of a plurality of slots cooperating with a parabolic reflector, in a second particular embodiment of the transition means between two adjacent layers, for dual polarization operation.
• the mode used is the TEM mode in which the electric field is oriented along the Z axis.
• the same considerations as those made above for the transition means can be repeated for a mode
• optical transition means in which the electric field is oriented along the Y axis.
• the only variation of the optical transition means would be a rotation of substantially 90 ° of the coupling slots made in the metal plate M.2 common to the two layers with parallel planes (d other angles of rotation could be chosen, for example a cross turned 45 °).
• each coupling slot is a cross slot 80 (see the description of Figures 17D and 17E), corresponding to the combination of two perpendicular slots.
• the two slots combined to form a cross are identical, but they may also be different.
• each cross slot is replaced by two perpendicular slots spaced from each other.
• Multibeam radiation if the antenna comprises several sources (the case of FIGS. 5 and 9 already described above).
• next-generation automotive radars must be compatible with both SRR (Short Radar Range, Wide Beam) and LRR (Long Range Radar, Narrow Beam) modes using a single antenna.
• SRR Short Radar Range, Wide Beam
• LRR Long Range Radar, Narrow Beam
• one solution is to add, in phase or not , a plurality of narrow beams of the LRR type to cover the angular range associated with the SRR mode, in particular because a wide beam SRR is a combination of narrow beams LRR.
• Figure 10 shows four radiation patterns 101 to 104 obtained with the antenna of Figure 9, for four different power configurations (each power configuration corresponding to the activation of three nearby sources respectively S6 / S1 / S2, S1 / S2 / S3, S2 / S3 / S4 and S3 / S4 / S5).
• the beam obtained has a beamwidth of 14 ° (against 6 ° for a single source) and a side lobe level SLL less than -2OdB. It is possible to scan from one configuration to another (just as it is possible to scan by activating the sources one by one).
• the basic concept illustrated in FIG. 10 can be generalized to beam shaping.
• another solution consists in feeding the sources of FIG. 9 successively, in order to modify the shape of the beam and thus to be able to widen the angular range of the antenna for the same beam. It is also possible according to this technique to create two different beams and pointing in two different directions.
• the electronic solution described above finds its application particularly when a large scanning speed is required. But in some applications, such as inter-vehicle or base-station telecommunications, slow scan speeds are accepted and it is then possible to use a mechanical solution to perform beam reconfiguration or 2D scanning.
• This mechanical solution which has already been mentioned above in the description of FIG. 3, consists of using means of mechanical displacement of the source, in a plane parallel to the superimposed layers of guide type with parallel planes.
• the arrow referenced 12 illustrates the path of movement of the source Sl.
• the beam width in the elevation plane is a function of the size of the antenna along the X axis, this means that the beam size in LRR mode should be twice that in SRR mode. In terms of reconfiguration, this means being able to increase or reduce the size along the X axis, automatically. From an antenna point of view, this can be done in several ways, for example by using shunt diodes along the opening (see FIG. 11), a discrimination of polarizations (see Figure 12) or multiple antennas in SRR mode (for example two juxtaposed antennas, without angular offset between them).
• the first two solutions are detailed below, in the case of a radiating part comprising a network of radiating slots, but it is clear that these solutions can be used in other configurations.
• the radiating part is considered, the feeding and guiding parts are for example those already described above.
• FIG. 11 shows the integration of shunt diodes 112 (or alternatively shunt loads), under the radiating part (along a line cutting in half the zone of the radiating part where the radiating slots 11 are located), allowing to connect connections 111 and 113 made on the metallized plates M.3 and M.2.
• These diodes are activated (activation means not shown in FIG. 11), for operation in the SRR mode, in order to halve the radiating portion by shorting or absorbing the incoming energy.
• the radiating portion is adapted to respond to different polarizations for the LLR and SRR modes.
• the cross slots operate in both the LRR and SRR modes, while the single slots only in the LRR mode.
• This solution is possible if the transition means (reflector and coupling slots) can operate in double polarization. This solution does not require any control electronics, the discrimination being carried out from a radiation point of view.
• Telecommunication applications usually require 3D scanning within a predefined cone.
• the antenna system must be able to scan the beam 360 ° in one plane, and in a smaller angular range in the other plane.
• the mechanical solution for scanning 3D is based on one or the other of the 2D scanning solutions proposed above (one mechanical and the other electronic). Indeed, these can be adopted to cover the most weak (sweep in a first plane (referenced P or P 'in FIG. 18), for example by adding a means of mechanical displacement of the whole of the antenna in the xy plane (plane parallel to the superimposed layers of the guide type). with parallel planes), we obtain a rotation of the main radiation plane (plane P or P ', Figure 18) in which the antenna radiates mainly.
• FIG. 13 is a top view of an antenna system 130, comprising a multilayer antenna according to one embodiment of the invention (two or more layers ) as described above.
• this antenna comprises a first supply portion (generating a first wave), a radiating portion and a guide portion.
• the guide portion guides the first wave from the first supply portion to the radiating portion.
• the guide portion comprises at least two superposed layers of guide type with parallel planes, and, for each pair of adjacent layers, first transition means between the adjacent layers, comprising a first reflector cooperating with a plurality of first coupling slots (the characteristics of such a plurality of coupling slots have already been discussed in detail above).
• the antenna system of Figure 13 further comprises a second power supply portion, generating a second wave.
• the guide portion also guides the second wave from the second supply portion to the radiating portion.
• the guide portion further comprises, for each pair of adjacent layers, second transition means between the adjacent layers, comprising a second reflector cooperating with a plurality of second slots (the characteristics of such a plurality of coupling slots have already been discussed in detail above). These second transition means are offset by 90 ° with respect to the first transition means.
• the reflector of the unique first (respectively second) optical transition means corresponds to a two-layer antenna; or
• the parabolic reflectors P. 1 and P 2 feed the radiating part, and control, for example, the direction of the beam in the planes YZ (plane P in FIG. 18) and XZ, respectively.
• each of the first and second feed portions comprises several interleaved sources (as in Figure 5 for example).
• the beam can be pointed in any direction of the upper space.
• the direction of the maximum radiation of the antenna structure can be found in any direction of the half-space above the radiating portion ( in the direction of the positive Z's).
• leak wave structures can be used. Their limitation is the beam frequency squinting. But for a low bandwidth ( ⁇ 10%), a determined beam operation is possible and the antenna structure is planar, low cost, light and is suitable for 3D electronic scanning with low losses compared to other solutions such as networks phases.
• the antennas of FIGS. 14, 15 and 16 comprise a feed portion (comprising a source, in this example, but it is also possible with several sources) and a radiating portion identical to those of the antenna of FIG. a guide part comprising three layers with parallel planes: a first layer with parallel planes itself comprising two metal plates Ml, M.2 located on either side of a dielectric substrate layer Sub.l (permitivity ⁇ rl ); a second layer with parallel planes itself comprising two metal plates M.2, M.3 located on either side of a dielectric substrate layer Sub.2 (permitivity S 12 ); and a third layer with parallel planes including itself two metal plates M.3, M.4 located on either side of a dielectric substrate layer Sub.3 (permitivity ⁇ r 3).
• a feed portion comprising a source, in this example, but it is also possible with several sources
• a radiating portion identical to those of the antenna of FIG. a guide part comprising three layers with parallel planes: a first layer
• the guide portion further comprises:
• a first optical transition means comprising an elliptical reflector R1 'and a plurality of coupling slots 10a' made in the metal plate M.2; and a second optical transition means comprising a parabolic reflector R2 'and a plurality of coupling slots 10b' formed in the metal plate M.3.
• the guide portion further comprises: a first optical transition means comprising a hyperbolic reflector R1 "and a plurality of coupling slots 10a" made in FIG. the metal plate M.2; and
• a second optical transition means comprising a parabolic reflector R2 "and a plurality of coupling slots 10b" made in the metal plate M.3.
• the guide portion further comprises:
• a first optical transition means comprising a parabolic reflector R1 '' and a plurality of coupling slots 10a '"made in the metal plate M.2; and a second optical transition means comprising a plane mirror
• the Gregorian or Cassegrain double-reflector systems make it possible to reduce the axial size of the optical transition system and to increase the performance with respect to the scanning capacitance in the YZ plane.
• the use of a plane mirror simply makes it possible to fold the antenna again (third layer) to further reduce the bulk. Indeed, the plane mirror reflects the plane wave sent by the parabolic reflector (first optical transition means) without affecting its nature.
• one of the first and second optical transition means is embodied according to the invention (i.e. with a plurality of coupling slots) and another is made in a conventional manner (i.e. with a single coupling slot).

Landscapes

• Variable-Direction Aerials And Aerial Arrays (AREA)
• Aerials With Secondary Devices (AREA)
• Waveguide Aerials (AREA)
• Radar Systems Or Details Thereof (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=41203887

Family Applications (1)

Country Status (5)

Families Citing this family (58)

Family Cites Families (12)

• 2009
  • 2009-04-02 FR FR0952158A patent/FR2944153B1/fr not_active Expired - Fee Related
• 2010
  • 2010-03-29 US US13/262,765 patent/US9246232B2/en not_active Expired - Fee Related
  • 2010-03-29 WO PCT/EP2010/054060 patent/WO2010112443A1/fr active Application Filing
  • 2010-03-29 EP EP10711224.5A patent/EP2415120B1/de not_active Not-in-force
  • 2010-03-29 JP JP2012502610A patent/JP5913092B2/ja active Active

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events