EP0487387B1 - Low profile microwave slot antenna - Google Patents

Low profile microwave slot antenna Download PDF

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Publication number
EP0487387B1
EP0487387B1 EP91403083A EP91403083A EP0487387B1 EP 0487387 B1 EP0487387 B1 EP 0487387B1 EP 91403083 A EP91403083 A EP 91403083A EP 91403083 A EP91403083 A EP 91403083A EP 0487387 B1 EP0487387 B1 EP 0487387B1
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EP
European Patent Office
Prior art keywords
slot
antenna according
cavity
line
core
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP91403083A
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German (de)
French (fr)
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EP0487387A1 (en
Inventor
Yves Commault
Georges Bonnet
Jacques Roquencourt
Alain Sehan
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Thales SA
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Thomson CSF SA
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    • 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
    • H01Q13/10—Resonant slot antennas
    • H01Q13/18—Resonant slot antennas the slot being backed by, or formed in boundary wall of, a resonant cavity ; Open cavity antennas
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/0006—Particular feeding systems
    • H01Q21/0075—Stripline fed arrays
    • H01Q21/0081—Stripline fed arrays using suspended striplines

Definitions

  • the present invention relates to a microwave antenna with a thin structure.
  • microstrip microstrip technology
  • the radiating elements are formed by discontinuities of the ribbon: they are designated by the name of radiating blocks ("patches").
  • pattern radiating blocks
  • the realization is simple since one can realize a radiant surface directly by photoengraving.
  • the performances are mediocre compared to those obtained with waveguides: non negligible losses, parasitic radiation of the supply lines, etc.
  • the radiating element is a slot photo-etched in a metallic plane and excited by a line according to the process indicated in Figure 1 (proposed by RM. Barret and MH. Barnes in 1951: “Survey of design techniques for flat profiles microwave antennas and arrays ", PS. Hall and JR James, The Radio and Electronic Engineer, flight. 48 No. 11 p. 545 - 565, Nov. 78, and: "Microwave printed circuits", RM. Barret and MH. Barnes, Radio and TV News, vol. 46, 1951, p. 16).
  • Document EP-A-0 295 003 discloses an antenna with a three-plate structure comprising a cavity with a depth equal to half a wavelength. This antenna is therefore also too thick.
  • the subject of the present invention is a microwave antenna whose thickness is as small as possible (for example less than 1/4 wavelength), which exhibits the lowest possible microwave losses, of low manufacturing cost, and having the minimum possible stray radiation from its supply lines, and the directivity of which can be adjusted within wide limits.
  • the present invention also relates to an array of slot microwave antennas which can integrate a large number of elementary antennas in the smallest possible space and having the minimum possible mutual interference between the microwave circuits and lines of supply of elementary antennas, and which can be integrated into a metal surface.
  • the object of the invention is a slot microwave antenna according to claim 1.
  • the known antenna 1 shown in FIG. 1 is of the triplate type with dielectric substrates. It comprises an assembly of two dielectric substrate plates 2, 3. The large external faces of this assembly are metallized. A slot 4 is photo-etched in one of the metallized surfaces. A metal strip 5 is formed on the large inner face of one of the plates, before their assembly. This strip 5 forms the excitation line of the slot 4.
  • the equivalent electrical diagram of such an antenna is that shown in FIG. 2: an inductance L1, in series in a characteristic impedance line Zc, coupled at an inductance L2 which is in parallel with a reactance jB and a pure resistance Yo.
  • the dependence of the impedance presented by the slit on the line has been shown as a function of the relative position of one with respect to the other (eccentricity).
  • FIG. 5 represents a section of line 10 "suspended triplate" as used by the present invention.
  • This line 10 is formed in a metallic structure comprising two plates 11, 12 of electrically conductive material applied one against the other. In the facing faces of each of these plates, a groove 13, 14 is formed respectively, these two grooves facing each other. Between the two plates, a film 15 of dielectric material is inserted on at least one face of which a strip 16 of electrically conductive material is formed.
  • This strip 16 is narrower than the grooves 13, 14 and, preferably, its longitudinal axis coincides with the longitudinal axis of the grooves.
  • Such a line has, compared to the line with dielectric substrates of FIG. 1, two important advantages: lower losses thanks to the elimination of the dielectric substrates, and shielding between adjacent lines thanks to the metallic structure and thanks to the possibility to make metallized holes in the film 15. This combination makes for each line a closed channel around each ribbon.
  • FIG. 6 shows a known antenna 17 with a radiating opening.
  • This antenna 17 is supplied by a line 18 in "suspended triplate", similar to that of FIG. 5.
  • the line 18 opens into a cavity 19 with circular section of diameter greater than 1/2 wavelength.
  • This cavity 19 comprises, going from the line 18 towards its outlet orifice, a cylindrical section 20 of length T close to or little different from 1/4 wave and an opening 21 flaring into a horn.
  • the cavity 19 ends in a cylindrical cavity 22 closed at its end, of depth P close to or little different from 1/4 wavelength.
  • the core 23 of the line 18 ends substantially at the center of the circle formed by the intersection of the film 24 of the line and cavity 19, that is to say 1/4 wavelength from the wall of the cavity.
  • the section 20 is used for filtering the evanescent upper modes generated by the free end of the core 23 of the triplate suspended in the cavity 19 of large dimensions.
  • This antenna 17 therefore has a large thickness structure (greater than 1/2 wavelength), which excludes its use in applications requiring a very thin structure.
  • FIGS. 7 and 8 show an antenna 25 according to the invention. In these figures, only one slot is shown, but it is understood that the same structure can comprise several slots, either touched independently of each other, or supplied from the same source via distributors.
  • the antenna 25 is formed in two plates 26, 27, of electrically conductive material, assembled, by any suitable means, one against the other with the interposition of a film 28 of dielectric material.
  • a groove, 29, 30 is formed over part of the length of these plates. These grooves can be straight or not.
  • One of the ends of the grooves 29, 30 ends at one of the sides of the corresponding plate.
  • These grooves both have a rectangular section, their depth, less than 1/8 of wavelength, can be constant over their entire length, or can vary, for at least one of the grooves, as illustrated in Figure 20 , and their widths are equal.
  • the depths of the grooves 29, 30 are equal to each other.
  • the plates 26, 27 are assembled so that the groove 29 faces the groove 30.
  • an electrically conductive strip 32 constituting the core of a three-plate line 31A therefore comprising the channel 31 and the core 32.
  • the longitudinal axis of the ribbon 31 is preferably coincident with the longitudinal axis of the channel 31.
  • the core 32 can either be extend to the closed end 33 of the channel 31 (as shown in FIG. 8) and therefore be short-circuited with the conductive plates 26, 27, or terminate shortly before this end, at a distance of protection against breakdown (as shown in figure 17).
  • a radiating slot is made in at least one of the plates 26, 27, referenced 34 in FIGS. 7 and 8.
  • Different forms of slots are described below.
  • the slot is rectilinear and perpendicular to the axis of the channel 31, at least as regards the part of this channel which is close to the slit.
  • This slot is of elongated rectangular shape, its ends being preferably rounded.
  • the slot is at a distance d1 from this end, d1 being less than 1/8 in length wave.
  • the distance d2 between this end and the closed end of the channel is simply intended to ensure a sufficiently high terminal impedance and the distance LE between the axis of the slot and the end of the core is substantially equal to 1/4 wavelength.
  • the slot has, on its medium fiber, a length LF generally between approximately 0.4 and 0.6 working wavelength. Its width LA can be between 0 and approximately 0.1 working wavelength, the latter value being able to be higher, provided that only one resonance mode can exist in the frequency band of use
  • the length LF of the slot is greater than the width LC of the channel 31. Consequently, the latter widens upstream of the slot, advantageously but not imperative at about 1/4 wavelength of the slit, and forms a cavity, referenced 35 in FIGS. 8 and 9.
  • the core 32 can also widen near the slot 34, downstream from the start of the cavity 35.
  • the cavity 35 may have a substantially rectangular shape, but it may have other shapes, as specified below.
  • the length LF of the slot 34 is a function of the wavelength used, and is substantially equal to 1/2 wavelength.
  • the respective dimensions, shapes and mutual positions of the end of the core 32, of the slot 34 and of the cavity 35 are parameters of adjustment to the design of the antenna, of adaptation of impedances, and, if necessary, adjustment of antenna networks, in particular for dense networks.
  • FIG. 10 shows the case where the end of the core is an open circuit, the distance LE between the axis of the slot and this end being substantially equal to 1/4 of wavelength.
  • the LCAV length of the cavity (35 or 37) and its shape, the position of the slot (34, 38) relative to this cavity, and the shape of the core are determined by the design of the antenna to obtain correct impedance adaptations between the line and the cavity, and between this cavity and the slot.
  • the slot 41 follows the shape of the end of the cavity 42, and the width d3 of the cavity is practically equal to the distance d4 between the external faces of the branches of the "U" formed by the slot.
  • the length d5 of the cavity is also determined to obtain a correct adaptation of the antenna.
  • the actual length of the slot 41 is in fact the length of its average fiber F, between its two ends 43, 44.
  • the slot 41 ′ has the same shapes and dimensions as those of the slot 41, while the cavity 42 ′ is wider, but shorter than the cavity 42.
  • the end 50 of the core of the line can be offset by a value d7.
  • the value d7 can even be greater than d6.
  • the width of the core 51 of the antenna feed line can be varied, close to the cavity 52 and / or inside this cavity.
  • We can, for example, form on this core a constriction 53 at the entrance of the cavity, then, over a short length, form an enlargement 54 (whose width can be equal to that of the core of the front line the constriction, be different), then narrow the end 55 of the core.
  • the variations in width of the web can be abrupt or progressive.
  • Such variations in width of the core introduce, in a manner known per se, either reactive effects (inductive or capacitive), or effects of impedance transformation (in particular by constituting a quarter-wave transformer).
  • metallized holes 56 in the film 57 of this structure, all around the perimeter delimiting the channel 58 of the line and the cavity 59.
  • the mutual distance of these holes is less than 1/8 of wavelength.
  • the cavity 60 has a substantially triangular shape (seen from above) gradually widening from the channel 61 of the supply line towards the slot 62.
  • the cavity 63 has a circular shape (seen from above).
  • the slot 64 can pass through the center of this cavity.
  • the end of the core 65 of the feed line can be, as shown in this figure 16, in open circuit, but it is understood that, as for all the embodiments of the antenna of the invention , this end may as well be short-circuited.
  • FIG. 17 shows another embodiment with the end of the core 66 in open circuit, the cavity 67 having a rectangular shape, and the slot 68 having a "U" shape.
  • the distance d8 between the axis of the central branch (that perpendicular to the axis of the core 66) of the slot and the end of the core 66 being substantially equal to 1/4 of wavelength.
  • FIG. 18 shows the simplified equivalent electrical diagram of the embodiments at the end of a core in open circuit.
  • This diagram includes a characteristic impedance line Zc, which corresponds to the antenna supply line, and continues beyond the start 69 of the cavity 67 to the slot 68, equivalent to an inductance 70 in series in the line, coupled to an inductor 71 in parallel with a resistor 72.
  • the line ends in a section 73 of length substantially equal to 1/4 wavelength, which closes on a capacity 74 which is equivalent to the open end of the line, the value of this capacity being, among other things, a function of the distance d9 between the end of the core and the cavity.
  • a partial reflector 75 known per se, arranged parallel to the metallic plane 76 in which slot 77 is made.
  • the radiating slot thus benefits from an image effect which can increase its directivity.
  • This partial reflector can be made either with a dielectric wall of appropriate thickness and permittivity (see for example "Image element antenna array for a monopulse tracking system for a missile" US Patent No. 3,990,078 2 Nov. 76, EC.
  • antenna adjustment parameters mentioned above must take into account the presence of this re partial flector placed in front of the radiating slot.
  • the distance d between the reflector 75 and the plane 76 is approximately half a wavelength.
  • the height of the channel 78 (step” 79) and / or of the cavity 80 ("step” 81) can be modified in places.
  • Such local modifications of the height of the channel and / or of the cavity produce the same kind of effects as the variations in width of the core, described above with reference to FIG. 13. It is thus possible, by modifying all these various parameters, optimize the operation of the antenna of the invention in the widest possible frequency band.
  • the two faces of the film 82 are metallized with a triplate structure to form the core 83, and the two faces 83A, 83B of this core are connected together by forming metallized holes 84 therein, preferably regularly spaced , at a step less than 1/8 wavelength.
  • metallized holes 84 can be formed only in the part of the core being in the cavity 85, or over the entire length of the core.
  • FIG. 22 shows the equivalent electrical diagram of the antenna of the invention.
  • the supply line of characteristic impedance Zc, arrives on a quadrupole (x1, x2, x3) which represents the input quadrupole in the cavity (transition between the line channel and the cavity).
  • This quadrupole is followed by a line section of length d7, representing the distance between the entry of the cavity and the slot.
  • the slit is equivalent to a series inductor L1 coupled to an inductor L2 in parallel on a reactance jB and a resistance Yo. Downstream of the slit, a section of line of length d8 closes on a reactance jBt (open circuit or short circuit, at a distance d7 from the slit).
  • FIG. 23 includes the elements already described above: plates 86, 87 and film 88 on which the core 89 is formed.
  • the slot, made in the plate 87, is referenced 90. This slot, thus that the cavity (not visible in the figure) can have any of the characteristics described above.
  • Two monopoles 91 are formed or fixed on the plate 87, 92 equidistant from the axis 93 of the slot, and arranged on an axis 94 perpendicular to the axis 93 and passing through the middle of the slot 90.
  • These two monopolies 91 , 92 are for example straight trunks of cylinders, perpendicular to the hollow or solid plate 87, the diameter of which is approximately equal to 1/10 of the length of the slot 90, and the height of which is substantially equal to or less than 1 / 4 wavelength.
  • Such monopoles are known per se (for example from "An improved element for use in array antenna", A. Clavin, DA Huebner and FJ Kilburg, IEEE Transactions on antennas and propagation, AP22, No. 4, July 74, p. 521). These monopoles make it possible to increase the directivity of the radiating slot 90 and / or to reduce its coupling to neighboring slots, if this slot is part of a network.
  • FIG. 24 shows a simplified example of supplying a network of slots from a common line 95, the network here comprising four slots, but it is understood that their number may be greater than this value.
  • Line 95 is subdivided into two branches 96, 97 which are each subdivided in turn into two sub-branches 98, 99 and 100, 101.
  • the common line, the branches and sub-branches are produced in the same way as the line of FIG. 5.
  • These four sub-branches each supply a slot, respectively 102, 103, 104 and 105.
  • a microwave circuit respectively 106, 107, 108 and 109.
  • These microwave circuits are for example phase shifters, but could also be amplifiers or attenuators. Of course, such microwave circuits could just as easily be inserted in the branches 96, 97 or in the line 95.
  • FIG. 25 shows a mode of installation of a microwave element 110 (phase shifter, amplifier, mixer, attenuator, etc.) in a line 111 (such as one of the lines 95 to 101) of the invention.
  • Line 111 is cut or interrupted over a length just sufficient to insert the element 110.
  • This element 110 can be produced using any suitable microwave technology, for example microstrip technology on an alumina substrate, and is enclosed in a housing 112 of electrically conductive material.
  • the input and output terminals 113, 114 of the element 110 are for example glass beads traversed by conductors and fixed to the housing 112.
  • the ends 115, 116 of the interrupted core of the line 111 are directly connected (for example by welding or metallization) at the terminals 113, 114 which are, of course, arranged in the plane of the core.
  • FIG. 26 shows, in a simplified manner, an enclosure 117 for microwave heating (that is to say operating in microwave).
  • a triplate structure 118 is formed (not shown in detail), so that the latter matches these walls.
  • This structure comprises several slots 119 arranged in appropriate locations on the walls so as to obtain the desired homogeneity or distribution of heating power. These slots are supplied from a common line 120 via distributors 121.
  • the antenna of the invention can also be used in a medical hyperthermia device.
  • the triplate structure of the invention is produced by forming two half-channels in two adjacent plates, these enclosing a metallized dielectric film.
  • the assembly of the two plates is done by screws, rivets or any other process.
  • the film can be produced from any material from the specialized trade (brands: Duro ⁇ d, Cuclad, etc.), the composition of which is generally a resin (polytetrafluoroethylene, polyimides, etc.), whether or not loaded with fibers of glass (woven or randomized).
  • the metallization of the film can be single or double sided; the latter choice may be advantageous from the point of view of losses and decoupling with an adjacent channel.
  • metallized holes can be useful for ensuring electrical symmetry when using a double-sided triplate core ( Figure 21).
  • the shape of the cavity is not limiting, the radius of curvature in the angles depends on the technology of realization of the plates: it can evolve from a null value (sharp angle) up to a value compatible with the presence of the slot (see figure 11a).
  • the slit being cut in a plane transverse to the propagation, intercepts the longitudinal lines of the current and consequently is modeled as an impedance in series according to the classic diagram of FIG. 2.
  • the line is terminated by a purely reactive impedance, which is a short circuit in the preferred case of FIG. 9 or an open circuit (case of the figures 10, 16 or 17).
  • the diagram of FIG. 2 becomes within the framework of the invention that of FIG. 22 where a transition quadrupole is introduced between the line "suspended plate" and the cavity coupled to the slot. If other reactive or transforming elements are used to adjust the load impedance to that of the line, they should be introduced in their place in this diagram.

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Description

La présente invention se rapporte à une antenne hyperfréquence à fente à structure de faible épaisseur.The present invention relates to a microwave antenna with a thin structure.

On sait réaliser depuis longtemps des antennes plates à fentes rayonnantes. Basées sur une structure d'alimentation à guides d'ondes, de nombreuses réalisations industrielles ont vu le jour. Ce mode de réalisation présente d'indéniables qualités au niveau des performances radioélectriques. Par contre, la difficulté de la réalisation mécanique conduit à un coût de fabrication élevé. Chercher à réduire ce coût va à l'encontre des performances (réduction de la bande de fréquences, ... ) et de la disponibilité de fonctions complexes si on reste dans la même technologie.It has long been known to make flat antennas with radiating slits. Based on a waveguide supply structure, numerous industrial projects have emerged. This embodiment has undeniable qualities in terms of radio performance. On the other hand, the difficulty of the mechanical production leads to a high manufacturing cost. Seeking to reduce this cost goes against performance (reduction of the frequency band, ...) and the availability of complex functions if we stay in the same technology.

Il est possible de réaliser des antennes plates avec un faible de coût de fabrication. On utilise pour cela la technologie microruban ("microstrip") dans laquelle les éléments rayonnants sont formés de discontinuités du ruban : on les désigne sous le nom de pavés ("patches" en anglais) rayonnants. La réalisation est simple puisque l'on peut réaliser une surface rayonnante directement par photogravure. Par contre, les performances sont médiocres comparées à celles obtenues avec des guides d'ondes : pertes non négligeables, rayonnement parasite des lignes d'alimentation, etc.It is possible to make flat antennas with a low manufacturing cost. This is done using microstrip technology ("microstrip") in which the radiating elements are formed by discontinuities of the ribbon: they are designated by the name of radiating blocks ("patches"). The realization is simple since one can realize a radiant surface directly by photoengraving. On the other hand, the performances are mediocre compared to those obtained with waveguides: non negligible losses, parasitic radiation of the supply lines, etc.

Il existe une autre technologie dans laquelle on peut mettre en oeuvre des procédés de photogravure (et par là, une réduction du coût). Il s'agit des lignes triplaques ("stripline"). Dans ce cas, l'élément rayonnant est une fente photogravée dans un plan métallique et excitée par une ligne selon le processus indiqué par la figure 1 (proposé par RM. Barret et MH. Barnes en 1951 : "Survey of design techniques for flat profiles microwave antennas and arrays", PS. Hall et JR James, The Radio and Electronic Engineer, vol. 48 N° 11 p. 545 - 565, Nov. 78, et : "Microwave printed circuits", RM. Barret et MH. Barnes, Radio and TV News, vol. 46, 1951, p. 16). La modélisation et la caractérisation de ce type d'élément rayonnant ont été faites successivement par AA. Oliner en 1954 ("The radiation conductance of a series slot in strip transmission line", AA. Oliner, IRE National Convention Record, 2, Part 8, p. 89 - 90 (1954)), RW. Breithaupt en 1968 ("Conductance data for off-set series slots in stripline" RW. Breithaupt, IEEE Trans-on Microwave Theory and technique, Nov 68, p. 969) et FS. Rao et BN Das en 1978 ("Impedance of off-centered stripline fed series slot", JS. Rao et BN. Das, IEEE Trans. on Antennas and Propagation AP26, Nov. 78, N° 6, P. 893). En première approximation le schéma équivalent communément admis est celui de la figure 2, décrite ci-dessous.There is another technology in which photogravure processes can be implemented (and thereby a reduction in cost). These are triplate lines ("stripline"). In this case, the radiating element is a slot photo-etched in a metallic plane and excited by a line according to the process indicated in Figure 1 (proposed by RM. Barret and MH. Barnes in 1951: "Survey of design techniques for flat profiles microwave antennas and arrays ", PS. Hall and JR James, The Radio and Electronic Engineer, flight. 48 No. 11 p. 545 - 565, Nov. 78, and: "Microwave printed circuits", RM. Barret and MH. Barnes, Radio and TV News, vol. 46, 1951, p. 16). The modeling and characterization of this type of radiating element were carried out successively by AA. Oliner in 1954 ("The radiation conductance of a series slot in strip transmission line", AA. Oliner, IRE National Convention Record, 2, Part 8, p. 89 - 90 (1954)), RW. Breithaupt in 1968 ("Conductance data for off-set series slots in stripline" RW. Breithaupt, IEEE Trans-on Microwave Theory and technique, Nov 68, p. 969) and FS. Rao and BN Das in 1978 ("Impedance of off-centered stripline fed series slot", JS. Rao and BN. Das, IEEE Trans. On Antennas and Propagation AP26, Nov. 78, N ° 6, P. 893). As a first approximation, the commonly accepted equivalent scheme is that of FIG. 2, described below.

On connaît par ailleurs ("Nouvelles structures d'antennes planes à rendement élevé" en lignes triplaque et lignes triplaque suspendu", E. Ramos, Colloque radar, Versailles, Mai 1984, et : "Une antenne plane à lignes sur substrat suspendu pour les applications de réception satellite à 12 GHz", E. Ramos, Acta Electronica, Revue du LEP/Philips, Vol. 27, N° 1/2 1985, p. 77-83) une antenne alimentée par des guides dont une extrémité est en court-circuit à environ un quart de longueur d'onde de l'extrémité de l'âme du triplaque et l'autre extrémité est ouverte sur un demi espace libre en s'évasant en forme de cornet (voir figure 6). Cette disposition conduit à une épaisseur non négligeable pour l'ensemble de la structure ; en effet, au tronçon quart d'onde, déjà mentionné, doit s'ajouter un tronçon de filtrage de modes évanescents (générés par l'extrémité libre de l'âme du triplaque) vers l'ouverture rayonnante.We also know ("New structures of high efficiency flat antennas" in triplate lines and suspended triplate lines ", E. Ramos, Radar symposium, Versailles, May 1984, and:" A plane antenna with lines on suspended substrate for applications for satellite reception at 12 GHz ", E. Ramos, Acta Electronica, LEP / Philips Journal, Vol. 27, N ° 1/2 1985, p. 77-83) an antenna supplied by guides, one end of which is in short-circuit to about a quarter wavelength from the end of the core of the triplate and the other end is open to half a free space, flaring in the shape of a horn (see Figure 6). leads to a significant thickness for the entire structure; in fact, to the quarter-wave section, already mentioned, must be added a section for filtering out evanescent modes (generated by the free end of the core of the triplate) towards the radiant opening.

On connaît d'après le document EP-A-0 295 003 une antenne à structure triplaque comportant une cavité de profondeur égale à une demi-longueur d'onde. Cette antenne est donc également trop épaisse.Document EP-A-0 295 003 discloses an antenna with a three-plate structure comprising a cavity with a depth equal to half a wavelength. This antenna is therefore also too thick.

La présente invention a pour objet une antenne hyperfréquence dont l'épaisseur soit la plus faible possible (par exemple inférieure à 1/4 de longueur d'onde), qui présente des pertes hyperfréquences le plus faibles possible, de faible coût de fabrication, et présentant le minimum possible de rayonnement parasite de ses lignes d'alimentation, et dont la directivité puisse être ajustée dans de larges limites.The subject of the present invention is a microwave antenna whose thickness is as small as possible (for example less than 1/4 wavelength), which exhibits the lowest possible microwave losses, of low manufacturing cost, and having the minimum possible stray radiation from its supply lines, and the directivity of which can be adjusted within wide limits.

La présente invention a également pour objet un réseau d'antennes hyperfréquences à fente qui puisse intégrer un grand nombre d'antennes élémentaires dans l'espace le plus restreint possible et présentant le minimum possible d'interférences mutuelles entre les circuits hyperfréquences et lignes d'alimentation des antennes élémentaires, et qui puisse être intégrable dans une surface métallique.The present invention also relates to an array of slot microwave antennas which can integrate a large number of elementary antennas in the smallest possible space and having the minimum possible mutual interference between the microwave circuits and lines of supply of elementary antennas, and which can be integrated into a metal surface.

L'objet de l'invention est une antenne hyperfréquence à fente selon la revendication 1.The object of the invention is a slot microwave antenna according to claim 1.

La présente invention sera mieux comprise à la lecture de la description de plusieurs modes de réalisation, pris comme exemples non limitatifs et illustrés par le dessin annexé, sur lequel :

  • la figure 1 est une vue schématique en perspective d'une antenne à fente alimentée par une ligne triplaque, selon l'art antérieur ;
  • la figure 2 est un schéma électrique équivalent de l'antenne de la figure 1 ;
  • la figure 3 est une vue schématique en perspective d'un autre mode de réalisation connu d'antenne à fente à structure triplaque ;
  • la figure 4 est une vue partielle en perspective d'une antenne à fente connue à cavité arrière ;
  • la figure 5 est une vue partielle en perspective d'une ligne "triplaque suspendu", connue en soi et utilisée par l'invention ;
  • la figure 6 est une vue en coupe d'une antenne à guide rayonnant, en technologie "triplaque suspendu" à cavité arrière ;
  • les figures 7 et 8 sont respectivement une vue en perspective et une vue en coupe axiale d'une antenne conforme à l'invention ;
  • les figures 9 à 17 sont des vues schématiques de dessus de différents modes de réalisation d'une antenne à fente conforme à l'invention ;
  • la figure 18 est un schéma électrique équivalent de l'antenne de la figure 17 ;
  • la figure 19 est une vue schématique en coupe d'une antenne conforme à l'invention, avec un réflecteur partiel ;
  • les figures 20 et 21 sont des vues en coupe d'autres modes de réalisation de l'antenne conforme à l'invention ;
  • la figure 22 est un schéma électrique équivalent d'une antenne conforme à l'invention ;
  • la figure 23 est une vue en perspective d'une variante de l'antenne conforme à l'invention ;
  • la figure 24 est une vue simplifiée de dessus d'un réseau d'antennes conforme à l'invention,
  • la figure 25 est une vue simplifiée en coupe d'un détail de réalisation du réseau de la figure 24, et
  • la figure 26 est une vue simplifiée en perspective d'une installation de chauffage par micro-ondes comportant des antennes conformes à l'invention.
The present invention will be better understood on reading the description of several embodiments, taken as nonlimiting examples and illustrated by the appended drawing, in which:
  • Figure 1 is a schematic perspective view of a slot antenna supplied by a triplate line, according to the prior art;
  • Figure 2 is an equivalent electrical diagram of the antenna of Figure 1;
  • Figure 3 is a schematic perspective view of another known embodiment of slot antenna with three-plate structure;
  • Figure 4 is a partial perspective view of a known slot antenna with rear cavity;
  • Figure 5 is a partial perspective view of a line "suspended plate", known per se and used by the invention;
  • Figure 6 is a sectional view of a radiating guide antenna, in "suspended triplate" technology with rear cavity;
  • Figures 7 and 8 are respectively a perspective view and an axial sectional view of an antenna according to the invention;
  • Figures 9 to 17 are schematic views from above of various embodiments of a slot antenna according to the invention;
  • Figure 18 is an equivalent electrical diagram of the antenna of Figure 17;
  • Figure 19 is a schematic sectional view of an antenna according to the invention, with a partial reflector;
  • Figures 20 and 21 are sectional views of other embodiments of the antenna according to the invention;
  • Figure 22 is an equivalent electrical diagram of an antenna according to the invention;
  • Figure 23 is a perspective view of a variant of the antenna according to the invention;
  • FIG. 24 is a simplified top view of an antenna array according to the invention,
  • FIG. 25 is a simplified view in section of a detail of the embodiment of the network of FIG. 24, and
  • Figure 26 is a simplified perspective view of a microwave heating installation comprising antennas according to the invention.

L'antenne connue 1 représentée en figure 1 est du type triplaque à substrats diélectriques. Elle comporte un assemblage de deux plaques de substrat diélectrique 2, 3. Les grandes faces extérieures de cet assemblage sont métallisées. Une fente 4 est photogravée dans l'une des surfaces métallisées. Une bande métallique 5 est formée sur la grande face intérieure de l'une des plaques, avant leur assemblage. Cette bande 5 forme la ligne d'excitation de la fente 4. En première approximation, le schéma électrique équivalent d'une telle antenne est celui représenté en figure 2 : une inductance L1, en série dans une ligne d'impédance caractéristique Zc, couplée à une inductance L2 qui est en parallèle avec une réactance jB et une résistance pure Yo. Par ailleurs, on a montré la dépendance de l'impédance présentée par la fente à la ligne en fonction de la position relative de l'une par rapport à l'autre (excentrement).The known antenna 1 shown in FIG. 1 is of the triplate type with dielectric substrates. It comprises an assembly of two dielectric substrate plates 2, 3. The large external faces of this assembly are metallized. A slot 4 is photo-etched in one of the metallized surfaces. A metal strip 5 is formed on the large inner face of one of the plates, before their assembly. This strip 5 forms the excitation line of the slot 4. As a first approximation, the equivalent electrical diagram of such an antenna is that shown in FIG. 2: an inductance L1, in series in a characteristic impedance line Zc, coupled at an inductance L2 which is in parallel with a reactance jB and a pure resistance Yo. Furthermore, the dependence of the impedance presented by the slit on the line has been shown as a function of the relative position of one with respect to the other (eccentricity).

Un inconvénient majeur de ce type d'élément résulte dans la génération de mode pair TEM entre les plans conducteurs (faces extérieures métallisées des plaques 2, 3), due à la charge asymétrique présentée par la fente. On ne peut s'affranchir de cet inconvénient que par le blindage de la zone de couplage par des piliers métalliques 6 rapportés ou des trous métallisés comme le montre la figure 3. Le blindage formé par ces trous constitue une cavité ("boxed stripline"). Par fermeture complète de cette cavité en dehors de la ligne d'alimentation, l'élément rayonnant ainsi constitué devient une fente à cavité arrière ("cavity backed slot") qui a fait l'objet d'une première description par AT. Adams ( "Design of transverse slot arrays fed by a boxed stripline" R. Shavit, RS. Elliot, IEEE Trans. on Antennas and Propagation vol. AP31 N° 4, Juillet 83 P. 545). Ces fentes (7) à cavité arrière (8) classiquement alimentées par une sonde axiale (9) (figure 4) ont fait l'objet de nombreuses études : théorique ("The input impedance of the rectangular cavity-backed slot antenna", CR. Cokrell, IEEE Trans. on antennas and propagation, vol. AP24, No. 3, Mai 76, p. 288, et : "Electromagnetic fields coupled into a cavity with a slot-aperture under resonant conditions", CC. Liang et DK. Cheng, IEEE Trans. on Antennas and propagation, Vol. AP30, No. 4, Juillet 82, page 664), expérimentale ("Experimental study of the impedance of cavity-backed slot antenna", SH. Long, IEEE Trans. on antennas and propagation, vol. AP23 No. 1, Janvier 75), d'optimisation ("Optimisation of cavities for slot antennas", ROE. Lagerlöf, Microwave journal, vol. 16, No. 10, Oct. 73, p. 12c), à bande élargie ("Cavity backed wide slot antennas", J. Hirokawa et co-auteurs, IEE Proc. vol. 136, Pt. H No. 1 Février 89, p. 29), et un ouvrage récent leur est consacré ("Microwave cavity antennas", A. Kumar et HD. Hristov, Artech House, 1989, Chap 2).A major drawback of this type of element results in the generation of TEM even mode between the conducting planes (metallized external faces of the plates 2, 3), due to the asymmetrical load presented by the slot. This disadvantage can only be overcome by shielding the coupling area with attached metal pillars 6 or metallized holes as shown in Figure 3. The shield formed by these holes constitutes a boxed stripline . By completely closing this cavity outside the supply line, the radiating element thus formed becomes a rear cavity slot ("cavity backed slot") which has been the subject of a first description by AT. Adams ("Design of transverse slot arrays fed by a boxed stripline" R. Shavit, RS. Elliot, IEEE Trans. On Antennas and Propagation vol. AP31 N ° 4, July 83 P. 545). These slots (7) with rear cavity (8) conventionally supplied by an axial probe (9) (FIG. 4) have been the subject of numerous studies: theoretical ("The input impedance of the rectangular cavity-backed slot antenna", CR Cokrell, IEEE Trans. On antennas and propagation, vol. AP24, No. 3, May 76, p. 288, and: "Electromagnetic fields coupled into a cavity with a slot-aperture under resonant conditions", CC. Liang and DK Cheng, IEEE Trans. On Antennas and propagation, Vol. AP30, No. 4, July 82, page 664), experimental ("Experimental study of the impedance of cavity-backed slot antenna", SH. Long, IEEE Trans. On antennas and propagation, vol. AP23 No. 1, January 75), optimization ("Optimization of cavities for slot antennas", ROE. Lagerlöf, Microwave journal, vol. 16, No. 10, Oct. 73, p. 12c ), wide band ("Cavity backed wide slot antennas", J. Hirokawa and co-authors, IEE Proc. vol. 136, Pt. H No. 1 February 89, p. 29), and a recent work devoted to them ("Microwave cavity antennas", A. Kumar and HD. Hristov, Artech House, 1989, Chap 2).

La figure 5 représente un tronçon de ligne 10 "triplaque suspendu" telle qu'utilisée par la présente invention. Cette ligne 10 est formée dans une structure métallique comportant deux plaques 11, 12 en matériau électriquement conducteur appliquées l'une contre l'autre. Dans les faces en vis-à-vis de chacune de ces plaques, on forme une rainure 13, 14 respectivement, ces deux rainures se faisant face. Entre les deux plaques, on insère un film 15 en matériau diélectrique sur au moins une face duquel est formé un ruban 16 en matériau électriquement conducteur. Ce ruban 16 est moins large que les rainures 13, 14 et, de préférence, son axe longitudinal est confondu avec l'axe longitudinal des rainures. Une telle ligne présente, par rapport à la ligne à substrats diélectriques de la figure 1, deux avantages importants : de plus faibles pertes grâce à la suppression des substrats diélectriques, et un blindage entre lignes adjacentes grâce à la structure métallique et grâce à la possibilité de pratiquer des trous métallisés dans le film 15. Cette combinaison réalise pour chaque ligne un canal fermé autour de chaque ruban.FIG. 5 represents a section of line 10 "suspended triplate" as used by the present invention. This line 10 is formed in a metallic structure comprising two plates 11, 12 of electrically conductive material applied one against the other. In the facing faces of each of these plates, a groove 13, 14 is formed respectively, these two grooves facing each other. Between the two plates, a film 15 of dielectric material is inserted on at least one face of which a strip 16 of electrically conductive material is formed. This strip 16 is narrower than the grooves 13, 14 and, preferably, its longitudinal axis coincides with the longitudinal axis of the grooves. Such a line has, compared to the line with dielectric substrates of FIG. 1, two important advantages: lower losses thanks to the elimination of the dielectric substrates, and shielding between adjacent lines thanks to the metallic structure and thanks to the possibility to make metallized holes in the film 15. This combination makes for each line a closed channel around each ribbon.

On a représenté en figure 6 une antenne connue 17 à ouverture rayonnante. Cette antenne 17 est alimentée par une ligne 18 en "triplaque suspendu", semblable à celle de la figure 5. La ligne 18 débouche dans une cavité 19 à section circulaire de diamètre supérieur à 1/2 longueur d'onde. Cette cavité 19 comporte, en allant de la ligne 18 vers son orifice de sortie, un tronçon cylindrique 20 de longueur T voisine ou peu différente de 1/4 d'onde et une ouverture 21 s'évasant en cornet. Du côté opposé par rapport à la ligne 18, la cavité 19 se termine par une cavité cylindrique 22 fermée à son extrémité, de profondeur P voisine ou peu différente de 1/4 de longueur d'onde. L'âme 23 de la ligne 18 se termine sensiblement au centre du cercle formé par l'intersection du film 24 de la ligne et de la cavité 19, c'est-à-dire à 1/4 de longueur d'onde de la paroi de la cavité. Le tronçon 20 sert au filtrage des modes supérieurs évanescents générés par l'extrémité libre de l'âme 23 du triplaque suspendu dans la cavité 19 de grandes dimensions. Cette antenne 17 a donc une structure d'épaisseur importante (supérieure à 1/2 longueur d'onde), qui en exclut l'emploi dans des applications nécessitant une structure très mince.FIG. 6 shows a known antenna 17 with a radiating opening. This antenna 17 is supplied by a line 18 in "suspended triplate", similar to that of FIG. 5. The line 18 opens into a cavity 19 with circular section of diameter greater than 1/2 wavelength. This cavity 19 comprises, going from the line 18 towards its outlet orifice, a cylindrical section 20 of length T close to or little different from 1/4 wave and an opening 21 flaring into a horn. On the opposite side with respect to the line 18, the cavity 19 ends in a cylindrical cavity 22 closed at its end, of depth P close to or little different from 1/4 wavelength. The core 23 of the line 18 ends substantially at the center of the circle formed by the intersection of the film 24 of the line and cavity 19, that is to say 1/4 wavelength from the wall of the cavity. The section 20 is used for filtering the evanescent upper modes generated by the free end of the core 23 of the triplate suspended in the cavity 19 of large dimensions. This antenna 17 therefore has a large thickness structure (greater than 1/2 wavelength), which excludes its use in applications requiring a very thin structure.

On a représenté en figures 7 et 8 une antenne 25 conforme à l'invention. Sur ces figures, on n'a représente qu'une seule fente, mais il est bien entendu qu'une même structure peut comporter plusieurs fentes, soit attentées indépendamment les uns des autres, soit alimentées à partir de la même source via des répartiteurs.FIGS. 7 and 8 show an antenna 25 according to the invention. In these figures, only one slot is shown, but it is understood that the same structure can comprise several slots, either touched independently of each other, or supplied from the same source via distributors.

L'antenne 25 est formée dans deux plaques 26, 27, en matériau électriquement conducteur, assemblées, par tout moyen approprié, l'une contre l'autre avec interposition d'un film 28 en matériau diélectrique. Dans chacune des plaques 26, 27, on forme, sur une partie de la longueur de ces plaques, une rainure, 29, 30 respectivement. Ces rainures peuvent être rectilignes ou non. L'une des extrémités des rainures 29, 30 aboutit à l'un des côtés de la plaque correspondante. Ces rainures ont toutes deux une section rectangulaire, leur profondeur, inférieure à 1/8 de longueur d'onde, peut être constante sur toute leur longueur, ou bien peut varier, pour au moins l'une des rainures, comme illustré en figure 20, et leurs largeurs sont égales. De préférence, les profondeurs des rainures 29, 30 sont égales entre elles. Les plaques 26, 27 sont assemblées de façon que la rainure 29 soit en vis-à-vis de la rainure 30.The antenna 25 is formed in two plates 26, 27, of electrically conductive material, assembled, by any suitable means, one against the other with the interposition of a film 28 of dielectric material. In each of the plates 26, 27, a groove, 29, 30 is formed over part of the length of these plates. These grooves can be straight or not. One of the ends of the grooves 29, 30 ends at one of the sides of the corresponding plate. These grooves both have a rectangular section, their depth, less than 1/8 of wavelength, can be constant over their entire length, or can vary, for at least one of the grooves, as illustrated in Figure 20 , and their widths are equal. Preferably, the depths of the grooves 29, 30 are equal to each other. The plates 26, 27 are assembled so that the groove 29 faces the groove 30.

On forme sur l'une des faces , ou sur les deux, du film 28, à l'intérieur du canal 31 défini par les rainures 29 et 30, un ruban 32 électriquement conducteur constituant l'âme d'une ligne triplaque 31A comprenant donc le canal 31 et l'âme 32. L'axe longitudinal du ruban 31 est, de préférence, confondu avec l'axe longitudinal du canal 31. L'âme 32 peut soit se prolonger jusqu'à l'extrémité fermée 33 du canal 31 (comme représenté en figure 8) et donc être en court-circuit avec les plaques conductrices 26, 27, soit se terminer peu avant cette extrémité, à une distance de protection contre tout claquage (comme représenté en figure 17).One forms on one or both sides of the film 28, inside the channel 31 defined by the grooves 29 and 30, an electrically conductive strip 32 constituting the core of a three-plate line 31A therefore comprising the channel 31 and the core 32. The longitudinal axis of the ribbon 31 is preferably coincident with the longitudinal axis of the channel 31. The core 32 can either be extend to the closed end 33 of the channel 31 (as shown in FIG. 8) and therefore be short-circuited with the conductive plates 26, 27, or terminate shortly before this end, at a distance of protection against breakdown (as shown in figure 17).

Un peu avant l'extrémité 33 du canal 31, on pratique dans au moins l'une des plaques 26, 27, une fente rayonnante, référencée 34 sur les figures 7 et 8. Différentes formes de fentes sont décrites ci-après. Dans le cas le plus simple, tel que celui illustré par les figures 7 à 10, 12, 13, 15, 16, 23 et 26, la fente est rectiligne et perpendiculaire à l'axe du canal 31, au moins en ce qui concerne la partie de ce canal qui est à proximité de la fente. Cette fente est de forme rectangulaire allongée, ses extrémités étant, de préférence, arrondies. Dans le cas où l'âme de la ligne triplaque est en court-circuit à l'extrémité 33 du canal (figure 8 par exemple), la fente est à une distance d1 de cette extrémité, d1 étant inférieure à 1/8 de longueur d'onde. Dans le cas où l'extrémité de l'âme de la ligne triplaque est en circuit ouvert (figure 10), la distance d2 entre cette extrémité et l'extrémité fermée du canal, est simplement destinée à assurer une impédance terminale suffisamment élevée et la distance LE entre l'axe de la fente et l'extrémité de l'âme est sensiblement égale à 1/4 de longueur d'onde. La fente présente, sur sa fibre moyenne, une longueur LF généralement comprise entre environ 0,4 et 0,6 longueur d'onde de travail. Sa largeur LA peut être comprise entre 0 et environ 0,1 longueur d'onde de travail, cette dernière valeur pouvant être plus élevée, à condition qu'un seul mode de résonance puisse exister dans la bande de fréquences d'utilisationA little before the end 33 of the channel 31, a radiating slot is made in at least one of the plates 26, 27, referenced 34 in FIGS. 7 and 8. Different forms of slots are described below. In the simplest case, such as that illustrated in FIGS. 7 to 10, 12, 13, 15, 16, 23 and 26, the slot is rectilinear and perpendicular to the axis of the channel 31, at least as regards the part of this channel which is close to the slit. This slot is of elongated rectangular shape, its ends being preferably rounded. In the case where the core of the triplate line is short-circuited at the end 33 of the channel (FIG. 8 for example), the slot is at a distance d1 from this end, d1 being less than 1/8 in length wave. In the case where the end of the core of the triplate line is in open circuit (FIG. 10), the distance d2 between this end and the closed end of the channel is simply intended to ensure a sufficiently high terminal impedance and the distance LE between the axis of the slot and the end of the core is substantially equal to 1/4 wavelength. The slot has, on its medium fiber, a length LF generally between approximately 0.4 and 0.6 working wavelength. Its width LA can be between 0 and approximately 0.1 working wavelength, the latter value being able to be higher, provided that only one resonance mode can exist in the frequency band of use

Bien entendu, dans le cas le plus général (figure 9, par exemple), la longueur LF de la fente est supérieure à la largeur LC du canal 31. Par conséquent, ce dernier s'élargit en amont de la fente, de façon avantageuse mais non impérative à environ 1/4 de longueur d'onde de la fente, et forme une cavité, référencée 35 sur les figures 8 et 9. L'âme 32 peut également s'élargir à proximité de la fente 34, en aval du début de la cavité 35. En vue de dessus, comme représenté en figure 9 par exemple, la cavité 35 peut avoir une forme sensiblement rectangulaire, mais elle peut avoir d'autres formes, comme précisé ci-dessous.Of course, in the most general case (FIG. 9, for example), the length LF of the slot is greater than the width LC of the channel 31. Consequently, the latter widens upstream of the slot, advantageously but not imperative at about 1/4 wavelength of the slit, and forms a cavity, referenced 35 in FIGS. 8 and 9. The core 32 can also widen near the slot 34, downstream from the start of the cavity 35. In top view, as shown in FIG. 9 for example, the cavity 35 may have a substantially rectangular shape, but it may have other shapes, as specified below.

Bien entendu, la longueur LF de la fente 34 est fonction de la longueur d'onde utilisée, et est sensiblement égale à 1/2 longueur d'onde. Les dimensions, formes et positions mutuelles respectives de l'extrémité de l'âme 32, de la fente 34 et de la cavité 35 sont des paramètres d'ajustement à la conception de l'antenne, d'adaptation d'impédances, et, le cas échéant, d'ajustement de réseaux d'antennes, en particulier pour des réseaux denses.Of course, the length LF of the slot 34 is a function of the wavelength used, and is substantially equal to 1/2 wavelength. The respective dimensions, shapes and mutual positions of the end of the core 32, of the slot 34 and of the cavity 35 are parameters of adjustment to the design of the antenna, of adaptation of impedances, and, if necessary, adjustment of antenna networks, in particular for dense networks.

On a représenté en figure 10 le cas où l'extrémité de l'âme est un circuit ouvert, la distance LE entre l'axe de la fente et cette extrémité étant sensiblement égale à 1/4 de longueur d'onde.FIG. 10 shows the case where the end of the core is an open circuit, the distance LE between the axis of the slot and this end being substantially equal to 1/4 of wavelength.

La longueur LCAV de la cavité (35 ou 37) et sa forme, la position de la fente (34, 38) par rapport à cette cavité, et la forme de l'âme sont déterminées à la conception de l'antenne pour obtenir des adaptations d'impédances correctes entre la ligne et la cavité, et entre cette cavité et la fente.The LCAV length of the cavity (35 or 37) and its shape, the position of the slot (34, 38) relative to this cavity, and the shape of the core are determined by the design of the antenna to obtain correct impedance adaptations between the line and the cavity, and between this cavity and the slot.

Ainsi que représenté en figures 11A et 11B, pour diminuer la surface d'encombrement de l'antenne, il est possible de replier les extrémités de la fente qui a ainsi une forme de "U". En figure 11A, la fente 41 épouse la forme de l'extrémité de la cavité 42, et la largeur d3 de la cavité est pratiquement égale à la distance d4 entre les faces extérieures des branches du "U" formé par la fente. La longueur d5 de la cavité est également déterminée pour obtenir une adaptation correcte de l'antenne. La longueur réelle de la fente 41 est en fait la longueur de sa fibre moyenne F, entre ses deux extrémités 43, 44.As shown in FIGS. 11A and 11B, to reduce the overall size of the antenna, it is possible to fold the ends of the slot which thus has a "U" shape. In FIG. 11A, the slot 41 follows the shape of the end of the cavity 42, and the width d3 of the cavity is practically equal to the distance d4 between the external faces of the branches of the "U" formed by the slot. The length d5 of the cavity is also determined to obtain a correct adaptation of the antenna. The actual length of the slot 41 is in fact the length of its average fiber F, between its two ends 43, 44.

En figure 11B, la fente 41′ a les mêmes formes et dimensions que celles de la fente 41, tandis que la cavité 42′ est plus large, mais plus courte que la cavité 42.In FIG. 11B, the slot 41 ′ has the same shapes and dimensions as those of the slot 41, while the cavity 42 ′ is wider, but shorter than the cavity 42.

Ainsi que représenté en figure 12, il peut être avantageux, pour implanter plus facilement l'antenne dans un réseau, de décentrer, d'une valeur d6, l'axe 45 de la ligne 46 par rapport à l'axe longitudinal 47 de la cavité 48 (l'axe 47 passe par le milieu M de la fente 49). En outre, pour ajuster l'impédance de la fente rayonnante par rapport à celle de la ligne, on peut excentrer, d'une valeur d7, l'extrémité 50 de l'âme de la ligne. La valeur d7 peut même être supérieure à d6.As shown in Figure 12, it may be advantageous, to more easily locate the antenna in a network, to offset, by a value d6, the axis 45 of the line 46 relative to the longitudinal axis 47 of the cavity 48 (the axis 47 passes through the middle M of the slot 49). Furthermore, to adjust the impedance of the radiating slit relative to that of the line, the end 50 of the core of the line can be offset by a value d7. The value d7 can even be greater than d6.

Comme représenté en figure 13, on peut faire varier la largeur de l'âme 51 de la ligne d'alimentation de l'antenne, à proximité de la cavité 52 et/ou à l'intérieur de cette cavité. On peut, par exemple, former sur cette âme un étranglement 53 à l'entrée de la cavité, puis, sur une courte longueur, former un élargissement 54 (dont la largeur peut être soit égale à celle de l'âme de la ligne avant l'étranglement, soit différente), puis rétrécir l'extrémité 55 de l'âme. Les variations de largeur de l'âme peuvent être brusques ou progressives. De telles variations de largeur de l'âme introduisent, de façon connue en soi, soit des effets réactifs (inductifs ou capacitifs), soit des effets de transformation d'impédance (en particulier en constituant un transformateur quart d'onde).As shown in FIG. 13, the width of the core 51 of the antenna feed line can be varied, close to the cavity 52 and / or inside this cavity. We can, for example, form on this core a constriction 53 at the entrance of the cavity, then, over a short length, form an enlargement 54 (whose width can be equal to that of the core of the front line the constriction, be different), then narrow the end 55 of the core. The variations in width of the web can be abrupt or progressive. Such variations in width of the core introduce, in a manner known per se, either reactive effects (inductive or capacitive), or effects of impedance transformation (in particular by constituting a quarter-wave transformer).

Selon le mode de réalisation de la figure 14, afin de réaliser un court-circuit franc entre les deux plaques conductrices de la structure triplaque autour de la cavité, on peut former des trous métallisés 56 dans le film 57 de cette structure, tout autour du périmètre délimitant le canal 58 de la ligne et la cavité 59. La distance mutuelle de ces trous est inférieure à 1/8 de longueur d'onde.According to the embodiment of Figure 14, in order to achieve a short circuit between the two conductive plates of the triplate structure around the cavity, one can form metallized holes 56 in the film 57 of this structure, all around the perimeter delimiting the channel 58 of the line and the cavity 59. The mutual distance of these holes is less than 1/8 of wavelength.

Selon la figure 15, la cavité 60 a une forme sensiblement triangulaire (en vue de dessus) s'élargissant progressivement depuis le canal 61 de la ligne d'alimentation vers la fente 62. Selon la figure 16, la cavité 63 a une forme circulaire (en vue de dessus). La fente 64 peut passer par le centre de cette cavité. L'extrémité de l'âme 65 de la ligne d'alimentation peut être, comme représenté sur cette figure 16, en circuit ouvert, mais il est bien entendu que, comme pour tous les modes de réalisation de l'antenne de l'invention, cette extrémité peut aussi bien être en court-circuit.According to Figure 15, the cavity 60 has a substantially triangular shape (seen from above) gradually widening from the channel 61 of the supply line towards the slot 62. According to FIG. 16, the cavity 63 has a circular shape (seen from above). The slot 64 can pass through the center of this cavity. The end of the core 65 of the feed line can be, as shown in this figure 16, in open circuit, but it is understood that, as for all the embodiments of the antenna of the invention , this end may as well be short-circuited.

On a représenté en figure 17 un autre mode de réalisation avec l'extrémité de l'âme 66 en circuit ouvert, la cavité 67 ayant une forme rectangulaire, et la fente 68 ayant une forme en "U". La distance d8 entre l'axe de la branche centrale (celle perpendiculaire à l'axe de l'âme 66) de la fente et l'extrémité de l'âme 66 étant sensiblement égale à 1/4 de longueur d'onde.FIG. 17 shows another embodiment with the end of the core 66 in open circuit, the cavity 67 having a rectangular shape, and the slot 68 having a "U" shape. The distance d8 between the axis of the central branch (that perpendicular to the axis of the core 66) of the slot and the end of the core 66 being substantially equal to 1/4 of wavelength.

On a représenté en figure 18 le schéma électrique équivalent simplifié des modes de réalisation à extrémité d'âme en circuit ouvert. Ce schéma comporte une ligne d'impédance caractéristique Zc, qui correspond à la ligne d'alimentation de l'antenne, et se poursuit au-delà du début 69 de la cavité 67 jusqu'à la fente 68, équivalente à une inductance 70 en série dans la ligne, couplée à une inductance 71 en parallèle avec une résistance 72. La ligne se termine par un tronçon 73 de longueur sensiblement égale à 1/4 de longueur d'onde, qui se referme sur une capacité 74 qui est équivalente à l'extrémité ouverte de la ligne, la valeur de cette capacité étant, entre autres, fonction de la distance d9 entre l'extrémité de l'âme et la cavité.FIG. 18 shows the simplified equivalent electrical diagram of the embodiments at the end of a core in open circuit. This diagram includes a characteristic impedance line Zc, which corresponds to the antenna supply line, and continues beyond the start 69 of the cavity 67 to the slot 68, equivalent to an inductance 70 in series in the line, coupled to an inductor 71 in parallel with a resistor 72. The line ends in a section 73 of length substantially equal to 1/4 wavelength, which closes on a capacity 74 which is equivalent to the open end of the line, the value of this capacity being, among other things, a function of the distance d9 between the end of the core and the cavity.

Il est possible, comme représenté en figure 19, d'associer à l'antenne de l'invention (dans l'un quelconque de ses modes de réalisation) un réflecteur partiel 75, connu en soi, disposé parallèlement au plan métallique 76 dans lequel est pratiquée la fente 77. La fente rayonnante bénéficie ainsi d'un effet d'image qui peut accroître sa directivité. On a référencé Fo le milieu de la fente, et F1, F2, F3, ... les images successives de Fo après les réflexions successives (r1, r2, r3, ... ) de l'onde émise sur le réflecteur 75. Ce réflecteur partiel peut être réalisé soit avec une paroi diélectrique d'épaisseur et de permittivité appropriées (voir par exemple "Image element antenna array for a monopulse tracking system for a missile" US Patent No. 3 990 078 2 nov. 76, EC. Belee, RC. Breithaupt, DL. Godwin et SH Walker" et "A highly thinned array using the image element" BH. Sasser (Motorola), Symposium on Antennas and Propagation, Sept. 1980, Québec), soit avec une grille métallique ou son complément ("Partially reflecting sheet arrays", G. Von Trentini, IRE Transactions on Antennas and Propagation, Oct. 56, p. 666 et "Leaky-wave multiple dechroïc beam formers", JR. James et co-auteurs, Electronic Letters, 31 Août 89, Vol 25 No. 18 p. 1209), soit encore en combinaisons multiples telles que décrites dans "Microwave cavity antennas", A. Kuwar et HD. Hristov, Artech House, 1989, Chap. 3). Bien entendu, les différents paramètres d'ajustage de l'antenne mentionnés ci-dessus doivent tenir compte de la présence de ce réflecteur partiel disposé en avant de la fente rayonnante. La distance d entre le réflecteur 75 et le plan 76 est d'environ une demi longueur d'onde.It is possible, as shown in FIG. 19, to associate with the antenna of the invention (in any of its embodiments) a partial reflector 75, known per se, arranged parallel to the metallic plane 76 in which slot 77 is made. The radiating slot thus benefits from an image effect which can increase its directivity. We have referenced Fo the middle of the slit, and F1, F2, F3, ... the successive images of Fo after the successive reflections (r1, r2, r3, ...) of the wave emitted on the reflector 75. This partial reflector can be made either with a dielectric wall of appropriate thickness and permittivity (see for example "Image element antenna array for a monopulse tracking system for a missile" US Patent No. 3,990,078 2 Nov. 76, EC. Belee, RC . Breithaupt, DL. Godwin and SH Walker "and" A highly thinned array using the image element "BH. Sasser (Motorola), Symposium on Antennas and Propagation, Sept. 1980, Quebec), either with a metal grid or its complement ( "Partially reflecting sheet arrays", G. Von Trentini, IRE Transactions on Antennas and Propagation, Oct. 56, p. 666 and "Leaky-wave multiple dechroïc beam formers", JR. James and co-authors, Electronic Letters, August 31 89, Vol 25 No. 18 p. 1209), or again in multiple combinations as described in "Microwave cavity antennas", A. Kuwar and HD. Hristov, Artech House, 1989, Chap. 3). antenna adjustment parameters mentioned above must take into account the presence of this re partial flector placed in front of the radiating slot. The distance d between the reflector 75 and the plane 76 is approximately half a wavelength.

Ainsi que représenté en figure 20, on peut modifier par endroits la hauteur du canal 78 ("marche" 79) et/ou de la cavité 80 ("marche" 81). De telles modifications locales de la hauteur du canal et/ou de la cavité produisent le même genre d'effets que les variations de largeur de l'âme, décrites ci-dessus en référence à la figure 13. On peut ainsi, en modifiant tous ces différents paramètres, optimiser le fonctionnement de l'antenne de l'invention dans la bande de fréquences la plus large possible.As shown in FIG. 20, the height of the channel 78 ("step" 79) and / or of the cavity 80 ("step" 81) can be modified in places. Such local modifications of the height of the channel and / or of the cavity produce the same kind of effects as the variations in width of the core, described above with reference to FIG. 13. It is thus possible, by modifying all these various parameters, optimize the operation of the antenna of the invention in the widest possible frequency band.

Selon la figure 21, on métallise les deux faces du film 82 d'une structure triplaque pour former l'âme 83, et on relie ensemble les deux faces 83A, 83B de cette âme en y formant des trous métallisés 84, de préférence régulièrement espacés, selon un pas inférieur à 1/8 de longueur d'onde. Ces trous métallisés peuvent être formés seulement dans la partie de l'âme se trouvant dans la cavité 85, ou bien sur toute la longueur de l'âme.According to FIG. 21, the two faces of the film 82 are metallized with a triplate structure to form the core 83, and the two faces 83A, 83B of this core are connected together by forming metallized holes 84 therein, preferably regularly spaced , at a step less than 1/8 wavelength. These metallized holes can be formed only in the part of the core being in the cavity 85, or over the entire length of the core.

On a représenté en figure 22 le schéma électrique équivalent de l'antenne de l'invention. La ligne d'alimentation, d'impédance caractéristique Zc, arrive sur un quadripôle (x1, x2, x3) qui représente le quadripôle d'entrée dans la cavité (transition entre le canal de la ligne et la cavité). Ce quadripôle est suivi d'un tronçon de ligne de longueur d7, représentant la distance entre l'entrée de la cavité et la fente. La fente équivaut à une inductance série L1 couplée à une inductance L2 en parallèle sur une réactance jB et une résistance Yo. En aval de la fente, un tronçon de ligne de longueur d8 se referme sur une réactance jBt (circuit ouvert ou court-circuit, à une distance d7 de la fente).FIG. 22 shows the equivalent electrical diagram of the antenna of the invention. The supply line, of characteristic impedance Zc, arrives on a quadrupole (x1, x2, x3) which represents the input quadrupole in the cavity (transition between the line channel and the cavity). This quadrupole is followed by a line section of length d7, representing the distance between the entry of the cavity and the slot. The slit is equivalent to a series inductor L1 coupled to an inductor L2 in parallel on a reactance jB and a resistance Yo. Downstream of the slit, a section of line of length d8 closes on a reactance jBt (open circuit or short circuit, at a distance d7 from the slit).

Le mode de réalisation de la figure 23 comporte les éléments déjà décrits ci-dessus : plaques 86, 87 et film 88 sur lequel est formée l'âme 89. La fente, pratiquée dans la plaque 87, est référencée 90. Cette fente, ainsi que la cavité (non visible sur la figure) peuvent présenter l'une quelconque des caractéristiques décrites ci-dessus. On forme ou on fixe sur la plaque 87 deux monopoles 91, 92 équidistants de l'axe 93 de la fente, et disposés sur un axe 94 perpendiculaire à l'axe 93 et passant par le milieu de la fente 90. Ces deux monopoles 91, 92 sont par exemple des troncs droits de cylindres, perpendiculaires à la plaque 87 creux ou pleins, dont le diamètre est approximativement égal au 1/10 de la longueur de la fente 90, et dont la hauteur est sensiblement égale ou inférieure à 1/4 de longueur d'onde. De tels monopôles sont connus en soi (par exemple d'après "An improved element for use in array antenna", A. Clavin, DA Huebner et FJ Kilburg, IEEE Transactions on antennas and propagation, AP22, No. 4, Juillet 74, p. 521). Ces monopôles permettent d'accroître la directivité de la fente rayonnante 90 et/ou de réduire son couplage à des fentes voisines, si cette fente fait partie d'un réseau.The embodiment of FIG. 23 includes the elements already described above: plates 86, 87 and film 88 on which the core 89 is formed. The slot, made in the plate 87, is referenced 90. This slot, thus that the cavity (not visible in the figure) can have any of the characteristics described above. Two monopoles 91 are formed or fixed on the plate 87, 92 equidistant from the axis 93 of the slot, and arranged on an axis 94 perpendicular to the axis 93 and passing through the middle of the slot 90. These two monopolies 91 , 92 are for example straight trunks of cylinders, perpendicular to the hollow or solid plate 87, the diameter of which is approximately equal to 1/10 of the length of the slot 90, and the height of which is substantially equal to or less than 1 / 4 wavelength. Such monopoles are known per se (for example from "An improved element for use in array antenna", A. Clavin, DA Huebner and FJ Kilburg, IEEE Transactions on antennas and propagation, AP22, No. 4, July 74, p. 521). These monopoles make it possible to increase the directivity of the radiating slot 90 and / or to reduce its coupling to neighboring slots, if this slot is part of a network.

On a représenté en figure 24 un exemple simplifié d'alimentation d'un réseau de fentes à partir d'une ligne commune 95, le réseau comportant ici quatre fentes, mais il est bien entendu que leur nombre peut être supérieur à cette valeur. La ligne 95 se subdivise en deux branches 96, 97 qui se subdivisent chacune à son tour en deux sous-branches 98, 99 et 100, 101. La ligne commune, les branches et sous-branches sont réalisées de la même façon que la ligne de la figure 5. Ces quatre sous-branches alimentent chacune une fente, respectivement 102, 103, 104 et 105. On intercale dans chacune de ces sous-branches un circuit hyperfréquences, respectivement 106, 107, 108 et 109. Ces circuits hyperfréquences sont par exemple des déphaseurs, mais pourraient aussi bien être des amplificateurs ou des atténuateurs. Bien entendu, de tels circuits hyperfréquences pourraient tout aussi bien être intercalés dans les branches 96, 97 ou dans la ligne 95.FIG. 24 shows a simplified example of supplying a network of slots from a common line 95, the network here comprising four slots, but it is understood that their number may be greater than this value. Line 95 is subdivided into two branches 96, 97 which are each subdivided in turn into two sub-branches 98, 99 and 100, 101. The common line, the branches and sub-branches are produced in the same way as the line of FIG. 5. These four sub-branches each supply a slot, respectively 102, 103, 104 and 105. In each of these sub-branches is inserted a microwave circuit, respectively 106, 107, 108 and 109. These microwave circuits are for example phase shifters, but could also be amplifiers or attenuators. Of course, such microwave circuits could just as easily be inserted in the branches 96, 97 or in the line 95.

On a représenté en figure 25 un mode d'implantation d'un élément hyperfréquence 110 (déphaseur, amplificateur, mélangeur, atténuateur, etc...) dans une ligne 111 (telle que l'une des lignes 95 à 101) de l'invention. On coupe ou interrompt la ligne 111 sur une longueur juste suffisante pour insérer l'élément 110. Cet élément 110 peut être réalisé selon toute technologie appropriée en hyperfréquences, par exemple en technologie microstrip sur substrat d'alumine, et est enfermé dans un boîtier 112 en matériau électriquement conducteur. Les bornes d'entrée et de sortie 113, 114 de l'élément 110 sont par exemple des perles de verre traversées par des conducteurs et fixées au boîtier 112. Les extrémités 115, 116 de l'âme interrompue de la ligne 111 sont directement reliées (par exemple par soudage ou métallisation) aux bornes 113, 114 qui sont, bien entendu, disposées dans le plan de l'âme. Ainsi, on garde l'avantage des faibles pertes de la ligne triplaque suspendu et celui de la compacité de l'élément 110.FIG. 25 shows a mode of installation of a microwave element 110 (phase shifter, amplifier, mixer, attenuator, etc.) in a line 111 (such as one of the lines 95 to 101) of the invention. Line 111 is cut or interrupted over a length just sufficient to insert the element 110. This element 110 can be produced using any suitable microwave technology, for example microstrip technology on an alumina substrate, and is enclosed in a housing 112 of electrically conductive material. The input and output terminals 113, 114 of the element 110 are for example glass beads traversed by conductors and fixed to the housing 112. The ends 115, 116 of the interrupted core of the line 111 are directly connected (for example by welding or metallization) at the terminals 113, 114 which are, of course, arranged in the plane of the core. Thus, the advantage of the low losses of the suspended triplate line and that of the compactness of the element 110 is retained.

On a représenté en figure 26, de façon simplifiée, une enceinte 117 de chauffage micro-ondes (c'est-à-dire fonctionnant en hyperfréquence). Sur la paroi intérieure de l'enceinte 117, on forme une structure triplaque 118 (non représentée en détail), de façon que celle-ci épouse ces parois. Cette structure comporte plusieurs fentes 119 disposées en des endroits appropriés des parois de façon à obtenir l'homogénéité ou la répartition de puissance de chauffage souhaitée. Ces fentes sont alimentées à partir d'une ligne commune 120 via des distributeurs 121. On peut également utiliser l'antenne de l'invention dans un appareil d'hyperthermie médicale.FIG. 26 shows, in a simplified manner, an enclosure 117 for microwave heating (that is to say operating in microwave). On the inner wall of the enclosure 117, a triplate structure 118 is formed (not shown in detail), so that the latter matches these walls. This structure comprises several slots 119 arranged in appropriate locations on the walls so as to obtain the desired homogeneity or distribution of heating power. These slots are supplied from a common line 120 via distributors 121. The antenna of the invention can also be used in a medical hyperthermia device.

En pratique, la structure triplaque de l'invention est réalisée en formant deux demi-canaux dans deux platines adjacentes, celles-ci enfermant un film diélectrique métallisé. L'assemblage des deux platines est fait par vis, rivets ou tout autre procédé.In practice, the triplate structure of the invention is produced by forming two half-channels in two adjacent plates, these enclosing a metallized dielectric film. The assembly of the two plates is done by screws, rivets or any other process.

Le film peut être réalisé à partir de tout matériau du commerce spécialisé (marques : Duroïd, Cuclad, etc... ) dont la composition est généralement une résine ( polytétrafluoréthylène, poly-imides, etc... ) chargée ou non de fibres de verre (tissées ou à répartition aléatoire). La métallisation du film peut être simple ou double face ; ce dernier choix pouvant être avantageux du point de vue des pertes et du découplage avec un canal adjacent.The film can be produced from any material from the specialized trade (brands: Duroïd, Cuclad, etc.), the composition of which is generally a resin (polytetrafluoroethylene, polyimides, etc.), whether or not loaded with fibers of glass (woven or randomized). The metallization of the film can be single or double sided; the latter choice may be advantageous from the point of view of losses and decoupling with an adjacent channel.

La mise en court-circuit des deux platines formant le canal de la ligne triplaque est assurée par des trous métallisés (voir figure 14). De même, des trous métallisés peuvent être utiles pour assurer la symétrie électrique lors de l'utilisation d'une âme de triplaque double face (figure 21).The two plates forming the channel of the triplate line are short-circuited by metallized holes (see Figure 14). Likewise, metallized holes can be useful for ensuring electrical symmetry when using a double-sided triplate core (Figure 21).

La forme de la cavité, telle qu'elle est donnée sur la figure 9, n'est pas limitative, le rayon de courbure dans les angles dépend de la technologie de réalisation des platines : il peut évoluer depuis une valeur nulle (angle vif) jusqu'à une valeur compatible avec la présence de la fente (voir figure 11a).The shape of the cavity, as it is given on figure 9, is not limiting, the radius of curvature in the angles depends on the technology of realization of the plates: it can evolve from a null value (sharp angle) up to a value compatible with the presence of the slot (see figure 11a).

La fente étant taillée dans un plan transversal à la propagation, intercepte les lignes longitudinales du courant et par conséquent se modélise comme une impédance en série suivant le schéma classique de la figure 2. Dans le cas particulier à l'invention, la ligne est terminée par une impédance purement réactive, qui est un court-circuit dans le cas préférentiel de la figure 9 ou un circuit ouvert (cas des figures 10, 16 ou 17). Dans le cas général, le schéma de la figure 2 devient dans le cadre de l'invention celui de la figure 22 où l'on introduit un quadripôle de transition entre la ligne "triplaque suspendu" et la cavité couplée à la fente. Dans l'hypothèse où d'autres éléments réactifs ou transformateurs seraient utilisés afin d'ajuster l'impédance de charge à celle de la ligne, ils seraient à introduire à leur place dans ce schéma.The slit being cut in a plane transverse to the propagation, intercepts the longitudinal lines of the current and consequently is modeled as an impedance in series according to the classic diagram of FIG. 2. In the particular case of the invention, the line is terminated by a purely reactive impedance, which is a short circuit in the preferred case of FIG. 9 or an open circuit (case of the figures 10, 16 or 17). In the general case, the diagram of FIG. 2 becomes within the framework of the invention that of FIG. 22 where a transition quadrupole is introduced between the line "suspended plate" and the cavity coupled to the slot. If other reactive or transforming elements are used to adjust the load impedance to that of the line, they should be introduced in their place in this diagram.

Pour la mise au point, trois méthodes sont possibles selon les moyens à la disposition de l'utilisateur :

  • 1) Caractérisation des différents éléments du schéma équivalent de la figure 22 :
    • on essaie d'évaluer, soit par des moyens mathématiques (analyse modale ou autre) soit par des mesures à l'analyseur de réseau, chacun des éléments du schéma : transformateur d'impédance, discontinuités réactives ...,
    • on introduit chacun des éléments, dont la dépendance vis-à-vis de sa géométrie est alors connue, dans un calcul d'optimisation (le critère étant la stabilité de l'impédance relative présentée à la ligne dans une bande de fréquences déterminée). Ceci suppose qu'il n'y ait aucune interdépendance entre les termes du schéma autre que celle modélisée : ainsi sont exclus les couplages par modes évanescents, ce qui, dans une structure aussi compacte que celle visée, est insuffisant.
  • 2) Mise au point strictement expérimentale :
    Elle suppose a priori une connaissance de la dépendance de certains termes en fonction de la géométrie (exemples : longueur de résonance de la fente, impédance de la fente en fonction de l'excentrement de la ligne d'excitation, etc...).
    Elle suppose une optimisation par approche logique et convergente vers l'objectif : en anglais, méthode "try and cut".
  • 3) Mise au point à l'ordinateur.
    Pour une géométrie déterminée, la distribution du champ et des courants dans la structure peut être calculée par exemple par la méthode des éléments finis : on en déduit l'impédance relative à la ligne. Par retouches successives sur la géométrie on doit converger vers le critère optimal choisi (épaisseur la plus faible possible de la structure triplaque). C'est un "try and cut" numérique.
    Dans ce qui précède, il n'a pas été fait mention du réflecteur partiel, il est sous-entendu que la définition de l'impédance de fente vue par la ligne prend en compte l'influence de ce réflecteur. Par ailleurs, la définition de ce réflecteur assurant un accroissement de directivité déterminé obéit aux règles connues concernant les parois diélectriques ou les grilles mécaniques et réseaux dichroïques.
    Le dispositif de l'invention est applicable dans toutes les structures rayonnantes où l'on recherche simultanément de faibles pertes du circuit d'alimentation (emploi du "triplaque suspendu" ) et une faible épaisseur ("triplaque suspendu" + fente).
    Cette faible épaisseur de la structure rayonnante est notamment recherchée dans les équipements aéroportés mais peut trouver son application chaque fois que son intégration s'en trouve facilitée dans un équipement où l'encombrement dans la direction du rayonnement (ou dans son voisinage) pose problème.
For the development, three methods are possible depending on the means available to the user:
  • 1) Characterization of the different elements of the equivalent diagram in Figure 22:
    • we try to evaluate, either by mathematical means (modal or other analysis) or by measurements with the network analyzer, each of the elements of the diagram: impedance transformer, reactive discontinuities ...,
    • each of the elements, whose dependence on its geometry is then known, is introduced into an optimization calculation (the criterion being the stability of the relative impedance presented to the line in a determined frequency band). This supposes that there is no interdependence between the terms of the diagram other than that modeled: thus are excluded the couplings by evanescent modes, which, in a structure as compact as that aimed, is insufficient.
  • 2) Strictly experimental development:
    It presupposes a priori knowledge of the dependence of certain terms as a function of the geometry (examples: resonance length of the slit, impedance of the slit as a function of the eccentricity of the excitation line, etc.).
    It supposes an optimization by logical and convergent approach towards the objective: in English, method "try and cut".
  • 3) Focus on the computer.
    For a given geometry, the distribution of the field and the currents in the structure can be calculated for example by the finite element method: we deduce the impedance relative to the line. By successive retouching on the geometry, we must converge towards the optimal criterion chosen (the smallest possible thickness of the three-ply structure). It's a digital "try and cut".
    In the foregoing, no mention has been made of the partial reflector, it is understood that the definition of the slit impedance seen by the line takes into account the influence of this reflector. Furthermore, the definition of this reflector ensuring a determined increase in directivity obeys the known rules concerning the dielectric walls or the mechanical grids and dichroic networks.
    The device of the invention is applicable in all radiating structures where small losses of the supply circuit are sought simultaneously (use of the "suspended triplate") and a small thickness ("suspended triplate" + slot).
    This small thickness of the radiating structure is particularly sought after in airborne equipment but can find its application each time its integration is facilitated in equipment where space in the direction of the radiation (or in its vicinity) is a problem.

Claims (21)

  1. Thin structure UHF slot antenna, comprising a feed line (31A, 40, 46, 61, 98 to 101) and a cavity, the said line being placed in a structure of "suspended stripline" type with two plates of electrically conducting material clasping a dielectric film (26-27-28, 86-87-88) on which the conducting core of the line is located, the end of the core of the line (32, 39, 50, 51, 65, 66, 89) penetrating into the said cavity (35, 37, 42, 42′, 48, 52, 59, 60, 63, 67, 85) in which at least one slot (34, 38, 41, 41′, 49, 62, 64, 68, 90, 119) is made, characterized in that the said feed line consists of two grooves placed opposite each other in each of the said two plates so as to form a channel around the said core, and in that the depth of the cavity is almost equal to the thickness of the channel (31, 78) of the feed line, this latter thickness being less than a quarter of the wavelength used.
  2. Antenna according to Claim 1, characterized in that it comprises a partial reflector (75) placed parallel to the metal plane (76) in which the slot (77) is made.
  3. Antenna according to Claim 1 or 2, characterized in that the end of the core of the line is short-circuited with the end wall (33) of the cavity.
  4. Antenna according to Claim 1 or 2, characterized in that the end of the core of the line is open-circuited (36, 65, 66).
  5. Antenna according to one of the preceding claims, characterized in that the slot is rectilinear (34, 38, 49, 62, 64, 119).
  6. Antenna according to one of the preceding claims, characterized in that the ends of the slot are folded back (41, 41′, 68, 102 to 105).
  7. Antenna according to one of the preceding claims, characterized in that the longitudinal axis (45) of the feed line is offset relative to the longitudinal axis of the cavity (47).
  8. Antenna according to one of the preceding claims, characterized in that the end (50) of the core of the feed line is offset relative to the middle (M) of the slot (49).
  9. Antenna according to one of the preceding claims, characterized in that the width of the end of the core of the feed line is variable (53-54-55).
  10. Antenna according to one of the preceding claims, characterized in that the thickness of the end of the channel of the feed line and/or the depth of the cavity exhibit variations (79, 81).
  11. Antenna according to one of the preceding claims, characterized in that the dielectric film (57) of the stripline structure comprises metallized holes (56) on the periphery of the channel (58) and/or of the cavity (59) putting the two electrically conducting plates of the stripline structure around the cavity and/or the channel into electrical contact.
  12. Antenna according to one of the preceding claims, characterized in that at least the end of the core of the line comprises a double-face metallization (83A, 83B) of the film of the stripline structure.
  13. Antenna according to one of the preceding claims, characterized in that it further comprises two monopoles (91, 92) placed perpendicular to the outside surface of the plate (87) containing the slot, on both sides of this slot.
  14. Antenna according to one of the preceding claims, characterized in that it comprises in its feed line (111) a box (112) containing a UHF element.
  15. Antenna according to Claim 14, characterized in that the element is a phase shifter.
  16. Antenna according to Claim 14, characterized in that the element is a mixer.
  17. Antenna according to Claim 14, characterized in that the element is an attenuator.
  18. Antenna according to Claim 14, characterized in that the element comprises an amplifier.
  19. UHF antenna array, characterized in that it includes antennas according to one of the preceding claims.
  20. Heating installation for microwaves, characterized in that it includes antennas according to one of the preceding claims.
  21. Medical hyperthermia apparatus, characterized in that it includes antennas according to one of Claims 1 to 19.
EP91403083A 1990-11-23 1991-11-15 Low profile microwave slot antenna Expired - Lifetime EP0487387B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9014621A FR2669776B1 (en) 1990-11-23 1990-11-23 SLOTTED MICROWAVE ANTENNA WITH LOW THICKNESS STRUCTURE.
FR9014621 1990-11-23

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EP0487387A1 EP0487387A1 (en) 1992-05-27
EP0487387B1 true EP0487387B1 (en) 1995-08-02

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GB2280558B (en) * 1993-07-31 1998-04-15 Plessey Semiconductors Ltd Doppler microwave sensor
JP3185513B2 (en) * 1994-02-07 2001-07-11 株式会社村田製作所 Surface mount antenna and method of mounting the same
JPH09501295A (en) * 1994-02-28 1997-02-04 ハゼルタイン・コーポレーション Slot array antenna
US5724049A (en) * 1994-05-23 1998-03-03 Hughes Electronics End launched microstrip or stripline to waveguide transition with cavity backed slot fed by offset microstrip line usable in a missile
GB2299213A (en) * 1995-03-20 1996-09-25 Era Patents Ltd Antenna array
RU2083035C1 (en) * 1995-06-05 1997-06-27 Александр Данилович Христич High-frequency planar-array antenna
KR100355263B1 (en) * 1995-09-05 2002-12-31 가부시끼가이샤 히다치 세이사꾸쇼 Coaxial Resonant Slot Antenna, Manufacturing Method and Portable Wireless Terminal
US5648786A (en) * 1995-11-27 1997-07-15 Trw Inc. Conformal low profile wide band slot phased array antenna
US5793263A (en) * 1996-05-17 1998-08-11 University Of Massachusetts Waveguide-microstrip transmission line transition structure having an integral slot and antenna coupling arrangement
FR2764739B1 (en) * 1997-06-13 1999-09-17 Thomson Csf NETWORK ANTENNA WITH RADIANT SLOTS
JP3340374B2 (en) * 1998-01-27 2002-11-05 株式会社東芝 Multi-frequency antenna
FR2784236B1 (en) * 1998-10-02 2006-06-23 Thomson Csf ANTENNA WITH FREQUENCY SWITCHING
JP3255403B2 (en) * 1998-12-24 2002-02-12 インターナショナル・ビジネス・マシーンズ・コーポレーション Patch antenna and electronic device using the same
EP1223637B1 (en) * 1999-09-20 2005-03-30 Fractus, S.A. Multilevel antennae
US6445906B1 (en) * 1999-09-30 2002-09-03 Motorola, Inc. Micro-slot antenna
TW432746B (en) * 1999-11-08 2001-05-01 Acer Neweb Corp Circular polarization antenna for wireless data communication
ATE302473T1 (en) * 2000-01-19 2005-09-15 Fractus Sa ROOM-FILLING MINIATURE ANTENNA
US6344829B1 (en) * 2000-05-11 2002-02-05 Agilent Technologies, Inc. High-isolation, common focus, transmit-receive antenna set
US6340951B1 (en) * 2000-06-02 2002-01-22 Industrial Technology Research Institute Wideband microstrip leaky-wave antenna
US6567053B1 (en) * 2001-02-12 2003-05-20 Eli Yablonovitch Magnetic dipole antenna structure and method
US6677915B1 (en) 2001-02-12 2004-01-13 Ethertronics, Inc. Shielded spiral sheet antenna structure and method
US7339531B2 (en) * 2001-06-26 2008-03-04 Ethertronics, Inc. Multi frequency magnetic dipole antenna structures and method of reusing the volume of an antenna
US6906667B1 (en) 2002-02-14 2005-06-14 Ethertronics, Inc. Multi frequency magnetic dipole antenna structures for very low-profile antenna applications
US6456243B1 (en) 2001-06-26 2002-09-24 Ethertronics, Inc. Multi frequency magnetic dipole antenna structures and methods of reusing the volume of an antenna
US6664931B1 (en) 2002-07-23 2003-12-16 Motorola, Inc. Multi-frequency slot antenna apparatus
US6911940B2 (en) * 2002-11-18 2005-06-28 Ethertronics, Inc. Multi-band reconfigurable capacitively loaded magnetic dipole
WO2005076407A2 (en) 2004-01-30 2005-08-18 Fractus S.A. Multi-band monopole antennas for mobile communications devices
ES2380576T3 (en) 2002-12-22 2012-05-16 Fractus, S.A. Unipolar multiband antenna for a mobile communications device
US6919857B2 (en) * 2003-01-27 2005-07-19 Ethertronics, Inc. Differential mode capacitively loaded magnetic dipole antenna
US6822611B1 (en) * 2003-05-08 2004-11-23 Motorola, Inc. Wideband internal antenna for communication device
DE102004050598A1 (en) * 2004-10-15 2006-04-27 Daimlerchrysler Ag Micro strip line antenna for use in automobile industry for transmitting and receiving e.g. circularly polarized satellite radio signal, has resonant unit enclosing recesses whose form deviates from rectangular form
US8738103B2 (en) 2006-07-18 2014-05-27 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices
US20080266194A1 (en) * 2007-04-27 2008-10-30 Sony Ericsson Mobile Communications Ab Slot Antenna with a Spiral Feed Element for Wireless Communication Devices
TWI449252B (en) * 2008-11-26 2014-08-11 Htc Corp Micro stripline structure
TWI407631B (en) * 2009-07-21 2013-09-01 Univ Nat Taiwan Antenna
US8547280B2 (en) * 2010-07-14 2013-10-01 Raytheon Company Systems and methods for exciting long slot radiators of an RF antenna
US8866687B2 (en) 2011-11-16 2014-10-21 Andrew Llc Modular feed network
US8558746B2 (en) 2011-11-16 2013-10-15 Andrew Llc Flat panel array antenna
US9160049B2 (en) 2011-11-16 2015-10-13 Commscope Technologies Llc Antenna adapter
DE102012111382A1 (en) * 2012-11-23 2014-05-28 GAT Gesellschaft für Antriebstechnik mbH Antenna structure for broadband transmission of electrical signals
BR112015013853B1 (en) * 2012-12-14 2021-12-07 Bae Systems Plc ANTENNA SUB-ARRANGE, ANTENNA ARRANGEMENT, METHOD OF MANUFACTURING AN ANTENNA ARRANGEMENT, AND, COOLING METHOD OF AN ANTENNA SUB-ARRANGE
JP6165649B2 (en) * 2014-02-04 2017-07-19 株式会社東芝 Antenna device and radar device
ES2568749B1 (en) * 2014-10-01 2017-02-07 Consejo Superior De Investigaciones Científicas (Csic) HEATING CELL, HEATER THAT MAKES SAME USE, HEATING SYSTEM AND USE OF IT
IL236739B (en) * 2015-01-15 2018-02-28 Mti Wireless Edge Ltd Antenna formed from plates and methods useful in conjunction therewith
EP3240101B1 (en) * 2016-04-26 2020-07-29 Huawei Technologies Co., Ltd. Radiofrequency interconnection between a printed circuit board and a waveguide
DE102017203513A1 (en) * 2017-03-03 2018-09-06 Robert Bosch Gmbh Dual band antenna as well as device with such a dual band antenna
US10686254B2 (en) * 2017-05-31 2020-06-16 The Boeing Company Wideband antenna system
DE102019108358A1 (en) * 2019-03-30 2020-10-01 Endress+Hauser SE+Co. KG Device for transmitting signals from an at least partially metallic housing
US11901601B2 (en) 2020-12-18 2024-02-13 Aptiv Technologies Limited Waveguide with a zigzag for suppressing grating lobes
US11444364B2 (en) 2020-12-22 2022-09-13 Aptiv Technologies Limited Folded waveguide for antenna
RU205041U1 (en) * 2021-01-17 2021-06-24 Евгений Вадимович Николаев RADIATOR FOR MICROWAVE ABLATION BASED ON A RESONANT STRUCTURE
US12058804B2 (en) 2021-02-09 2024-08-06 Aptiv Technologies AG Formed waveguide antennas of a radar assembly
US11962085B2 (en) 2021-05-13 2024-04-16 Aptiv Technologies AG Two-part folded waveguide having a sinusoidal shape channel including horn shape radiating slots formed therein which are spaced apart by one-half wavelength
US11616282B2 (en) 2021-08-03 2023-03-28 Aptiv Technologies Limited Transition between a single-ended port and differential ports having stubs that match with input impedances of the single-ended and differential ports

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3172112A (en) * 1961-05-29 1965-03-02 Elwin W Seeley Dumbbell-loaded folded slot antenna
US4130822A (en) * 1976-06-30 1978-12-19 Motorola, Inc. Slot antenna
FR2487588A1 (en) * 1980-07-23 1982-01-29 France Etat DOUBLE REPLIES IN PLATES FOR VERY HIGH FREQUENCY AND NETWORKS OF SUCH DOUBLETS
US4443802A (en) * 1981-04-22 1984-04-17 University Of Illinois Foundation Stripline fed hybrid slot antenna
US4587524A (en) * 1984-01-09 1986-05-06 Mcdonnell Douglas Corporation Reduced height monopole/slot antenna with offset stripline and capacitively loaded slot
JPH0685487B2 (en) * 1985-05-18 1994-10-26 日本電装株式会社 Dual antenna for dual frequency
US4710775A (en) * 1985-09-30 1987-12-01 The Boeing Company Parasitically coupled, complementary slot-dipole antenna element
EP0295003A3 (en) * 1987-06-09 1990-08-29 THORN EMI plc Antenna
US5061943A (en) * 1988-08-03 1991-10-29 Agence Spatiale Europenne Planar array antenna, comprising coplanar waveguide printed feed lines cooperating with apertures in a ground plane

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DE69111757T2 (en) 1995-12-14
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US5337065A (en) 1994-08-09
EP0487387A1 (en) 1992-05-27
DE69111757D1 (en) 1995-09-07

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