EP0122834B1 - Microwave propagation-mode transformer - Google Patents

Microwave propagation-mode transformer Download PDF

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Publication number
EP0122834B1
EP0122834B1 EP84400542A EP84400542A EP0122834B1 EP 0122834 B1 EP0122834 B1 EP 0122834B1 EP 84400542 A EP84400542 A EP 84400542A EP 84400542 A EP84400542 A EP 84400542A EP 0122834 B1 EP0122834 B1 EP 0122834B1
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Prior art keywords
transformer
axis
section
mode
gyrotron
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EP84400542A
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German (de)
French (fr)
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EP0122834A1 (en
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Georges Mourier
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/027—Collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators

Definitions

  • the present invention relates to a microwave propagation mode transformer for gyrotron type power millimetric oscillators which operate on high modes.
  • Gyrotrons are now used to heat plasmas in order to bring them to a thermonuclear temperature.
  • the problem which arises is that, to obtain a significant radiation, it is necessary to pass from a complex mode, the circular mode TE one for example, which is produced in the cavity of revolution of the gyrotrons, to a mode where the electric field is linearly polarized, and is therefore substantially parallel to a given direction, and even where it is preferable to pass to a plane wave.
  • the present invention makes it possible to solve the problem of passing from a complex mode, of the TE on type, to a mode in which the electric field is substantially parallel to a given direction, and even to a plane wave.
  • the present invention relates to a transformer of microwave propagation modes, constituted by a waveguide, of substantially elliptical section, and of increasing eccentricity along the axis of the transformer, this transformer ensuring the transition to a mode where the field electric is substantially parallel to a given direction, characterized in that:
  • This patent application in fact relates to an antenna which receives a hybrid mode, such as the HE 11 mode - see page 3, line 7 of this application - which allows the antenna to radiate.
  • This antenna transforms this mode into another mode which improves the radiation of the antenna.
  • the mode transformer is connected to the cavity of revolution of a gyrotron, which provides it with a complex mode, such as for example the TE 12 mode of FIG. 1, which does not allow the radiation.
  • the mode transformer ensures the transition from a TE type mode on which does not allow radiation to a mode which allows to obtain a high radiation, that is to say a mode where the electric field is substantially parallel to a given direction. It does not seem obvious to us at all given the antenna function of the waveguide of increasing ellipticity of the cited European patent application to use this device, in association with a gyrotron, and with a different function.
  • FIG 1 there is shown the electric field lines in the circular cross section of the cavity 1 of a gyrotron, in the case where a TE o2 mode is established in this cavity.
  • the solid circles indicate the areas where the electric field is maximum and the dotted circles indicate the areas where the electric field is zero.
  • This circular and symmetrical TE 02 mode does not allow radiation.
  • Figure 2 shows the distribution of electric field lines in the cross section of a guide wave 2 of elliptical section placed following the cavity of a gyrotron where a TE o2 mode is established as in Figure 1.
  • a and b the major axis and the minor axis of the ellipse.
  • the minor axis b twice equals the interior radius R of the gyrotron cavity.
  • Figure 3 shows the distribution of the electric field lines in the cross section of a system consisting of two parallel conductive plates, bearing the reference 3.
  • the distance d between the plates is taken equal to twice the radius R of the cavity of the gyrotron. It can be seen that the electric field lines are parallel to the x direction.
  • the mode transformer according to the invention makes it possible to pass from the TE o2 mode established in the circular section cavity of a gyrotron and which does not allow radiation to a mode where the electric field is substantially parallel to the direction x by using a waveguide, of substantially elliptical section, and of increasing eccentricity, and which allows a significant radiation.
  • the eccentricity is zero when a equals b, i.e. when the ellipse becomes a circle.
  • the mode transformer according to the invention consists of a waveguide of substantially elliptical section, and of increasing eccentricity, that is to say that the cross section of this transformer has the shape of an ellipse whose the major axis a increases and tends towards the cross section of FIG. 3 which is that of a system made up of two parallel plates which can be assimilated to the cross section of an ellipse with eccentricity equal to 1.
  • the field lines have the distribution indicated in Figure 2 and then tend towards the distribution of Figure 3, that is to say that when the eccentricity of the ellipse increases, the field lines become more and more parallel to the x direction.
  • the frequency f and the radius R of the cavity are linked by the following relation: where c is the speed of light. This relation expresses that the frequency is very close to the cutoff frequency.
  • the transformer according to the invention can be produced by carrying out a metallic deposit on a matrix by electrolysis, as is done to produce waveguides.
  • FIG. 4 illustrates another method making it possible to obtain a transformer of modes of elliptical section, of increasing eccentricity.
  • FIG. 5 represents a mode transformer 9 which is obtained in this way.
  • Figure 6 is a projection of sections made perpendicular to the Oz axis on the horn shown in Figure 5.
  • the small axis b of the ellipse, directed along the axis Oy slightly increases along the Oz axis.
  • the horn shown in Figure 5 is a good embodiment of the mode transformer because it is shown that as the eccentricity of an ellipse increases, the energy electromagnetic is concentrated between two hyperbolas H, and H z having F, and F z for foci.
  • FIG. 7 shows an ellipse with its two foci F, and F 2 and the two hyperbolas H 1 and H Z. If the dimensions of the guide are large compared to the wavelength, the distribution of the electrical energy density E 2 is close to a Gaussian function as shown in FIG. 8.
  • FIGS. 7 and 8 shows that it is possible without disturbance to modify the walls of the guide and even the hatched spaces limited by the hyperbolas H, and H 2 of FIG. 7.
  • the transformer according to the invention it is possible to consider to give the order of magnitude of the ellipticity that in the final section of the transformer, there are some wavelengths between the two foci F, and F Z.
  • a mode transformer consisting of a guide of elliptical section, of increasing eccentricity, can therefore be produced by the horn of FIG. 5, consisting of two parts of cone of revolution.
  • the two half-horns 7 can come from two different truncated cones. It is necessary to obtain a horn comprising two parts of decreasing curvature and whose distance to the axis z increases less quickly than the radius of curvature, which will play the role of ellipses of increasing eccentricity.
  • the transformer according to the invention may comprise on the parts close to the ends of the long axis of the cavities in which there is an absorbent material which absorbs any mode other than the desired mode.
  • FIG. 9 represents the cross section of a mode transformer obtained by brazing two parts of truncated cone. The parts close to the ends of the major axis were dug to obtain the elongated volumes V 1 and V z which contain an absorbent material 10. Since there is only very little energy stored near the ends of the major axis, the volumes V, and V 2 do not disturb the operation of the mode transformer.
  • FIG. 9 the field lines obtained from a TR 02 mode are shown in the circular cavity of the gyrotron. It can be seen that the electric field lines are substantially parallel to the x axis, and therefore to the major axis of the ellipse a.
  • FIG. 10 shows an embodiment of the transformer according to the invention.
  • FIG. 10 is a perspective view where we see, on the left side a gyrotron 11, which is symbolically represented by a cylinder, followed by the mode transformer according to the invention 9 which is made up of two mirrors M, and M Z. These two mirrors are concave, They are arranged on either side of the Oz axis, perpendicular to the y axis, and face each other. These two mirrors are contained in a vacuum enclosure which is not shown in FIG. 10.
  • the outline of the window 12 is shown in dotted lines which ensures the vacuum tightness of the enclosure containing the mirrors M, and M 2 .
  • the transformer according to the invention can be found, as is the case in FIG. 10, in the same vacuum enclosure as the gyrotron. It can also be placed at the exit of a gyrotron of usual structure.
  • the shape of the mirrors M 1 and M 2 is chosen so that the sections perpendicular to the z axis of the transformer according to the invention thus produced are substantially elliptical and of increasing eccentricity along the oz axis, provided that not take into account the ends of the major axis of these ellipses where we have seen that the electric field is very weak.
  • the transformer according to the invention can ensure the passage, modes other than the TE modes is in a mode where the electric field is substantially parallel to a given direction.
  • Figures 11 and 13 show the electric field lines in the cross section of cavity 1 of the gyrotron when a TE mode 12 and a TE mode 22 is established in this cavity.
  • Figures 12 and 14 show the electric field lines in the cross section of the transformer according to the invention consisting of the two mirrors M, and M 2 which is placed following the cavity of a gyrotron where the TE mode is established respectively. 12 of FIG. 11 and the TE mode 22 of FIG. 13. A TE c mode and a TE d mode of open guide are obtained in the transformer according to the invention. It can be seen that the electric field lines are directed substantially along the x axis and have 3 and 4 successive alternations between M 1 and M 2 .
  • the continuous magnetic field created by a focusing solenoid 21 placed around the gyrotron, decreases, the electron beam diverges and strikes the walls of the transformer 9.
  • focusing means are arranged around the transformer which direct the electron beam onto collector plates Ci and C 2 .
  • These plates are arranged on either side of the Oz axis, perpendicular to the x axis, and face each other. They are therefore located on the parts close to the ends of the long axis of the ellipses constituting the section of the transformer. They are contained in the vacuum enclosure containing the mirrors M 1 and M 2 .
  • the focusing means which are not shown in FIG. 10, can consist for example of two elongated windings pressed along the transformer 9 in the manner of the deflection coils of the television tubes, and connected to a DC voltage source . These windings are traversed by currents rotating in opposite directions around the x axis.
  • Collector zones can be provided in the other embodiments of the transformer according to the invention when the transformer is placed inside the vacuum enclosure.
  • the volumes V I and V2 can be used to collect the electron beam.
  • the configurations of the electric field represented in FIGS. 2, 3, 9, 12 and 14 have in common the following characteristics. There is propagation in the z direction. In the y direction there is a standing wave and in the x direction there is a slow variation in amplitude, with no phase variation.
  • This wave system can be represented by two crossed plane waves O 1 and O2, the paths of which have been shown in FIG. 15, in the plane yOz, in a section of waveguide 13 following the transformer according to the invention and having two walls parallel to the Oz axis.
  • This waveguide section has the same section as the final section of the transformer and has a constant section along the axis Oz. It has been shown on the right-hand side of FIG. 15 that when the guide is interrupted, the geometric optics indicate that two beams of plane waves 14 and 15 of different directions are obtained.
  • the two beams 14 and 15 remain parallel before diverging by diffraction after a distance L R , called Rayleigh distance, which is equal to:
  • the transformer according to the invention is followed by a section of waveguides having the same section as the final section of the transformer and having a constant section along the axis. Oz.
  • This part 18 comprises two mirrors M 3 and M 4 .
  • the inclination of these two mirrors is chosen so that the mirror M 3 receives the plane wave 14 and reflects it vertically in FIG. 16 and so that the mirror M 4 receives the plane wave 15 and also reflects it vertically.
  • the waves reflected by the two mirrors must also not be disturbed.
  • the mirror M 3 is parallel to the wave 15.
  • Part 18 ends with a window 20 which is vacuum tight and transparent to radiation.
  • Mirrors M 3 and M 4 can be given a spherical or cylindrical curvature so as to compensate over a certain length for the diffraction of the beam coming from the tube through the window.
  • Part 18 can also allow a single parallel beam to be obtained while using only a single curved mirror, more bulky than the two mirrors M, and M 2 .
  • the embodiment of Figure 16 makes the main axis of the Oz tube vertical, which. is preferable for its mechanical strength, while the parallel beam obtained is horizontal, which is practical for users.

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  • Waveguide Switches, Polarizers, And Phase Shifters (AREA)

Description

La présente invention concerne un transformateur de modes de propagation hyperfréquence destiné à des oscillateurs millimétriques de puissance du type gyrotron qui fonctionnent sur des modes élevés. Les gyrotrons, sont maintenant utilisés pour chauffer des plasmas dans le but de les amener à une température thermonucléaire. Le problème qui se pose est que, pour obtenir un rayonnement important, il faut passer d'un mode complexe, le mode circulaire TEon par exemple, qui est produit dans la cavité de révolution des gyrotrons, à un mode où le champ électrique est polarisé linéairement, et est donc sensiblement parallèle à une direction donnée, et même où il faut passer de préférence à une onde plane.The present invention relates to a microwave propagation mode transformer for gyrotron type power millimetric oscillators which operate on high modes. Gyrotrons are now used to heat plasmas in order to bring them to a thermonuclear temperature. The problem which arises is that, to obtain a significant radiation, it is necessary to pass from a complex mode, the circular mode TE one for example, which is produced in the cavity of revolution of the gyrotrons, to a mode where the electric field is linearly polarized, and is therefore substantially parallel to a given direction, and even where it is preferable to pass to a plane wave.

La présente invention permet de résoudre le problème du passage d'un mode complexe, du type TEon, à un mode cù le champ électrique est sensiblement parallèle à une direction donnée, et même à une onde plane.The present invention makes it possible to solve the problem of passing from a complex mode, of the TE on type, to a mode in which the electric field is substantially parallel to a given direction, and even to a plane wave.

La présente invention concerne un transformateur de modes de propagation hyperfréquence, constitué par un guide d'onde, de section sensiblement elliptique, et d'excentricité croissante le long de l'axe du transformateur, ce transformateur assurant le passage à un mode où le champ électrique est sensiblement parallèle à une direction donnée, caractérisé en ce que:The present invention relates to a transformer of microwave propagation modes, constituted by a waveguide, of substantially elliptical section, and of increasing eccentricity along the axis of the transformer, this transformer ensuring the transition to a mode where the field electric is substantially parallel to a given direction, characterized in that:

  • - ce transformateur est relié à la cavité d'un gyrotron qui lui fournit un mode complexe du type Teon, le transformateur étant placé dans la même enceinte à vide que le gyrotron;- This transformer is connected to the cavity of a gyrotron which provides it with a complex mode of the Te on type, the transformer being placed in the same vacuum enclosure as the gyrotron;
  • - ce transformateur est constitué de deux miroirs concaves, qui se font face, la forme des miroirs étant telle que les sections perpendiculaires à l'axe du transformateur soient sensiblement elliptiques et d'excentricité croissante le long de cet axe, à condition de ne pas tenir compte des extrémités du grand axe de ces ellipses;- this transformer consists of two concave mirrors, which face each other, the shape of the mirrors being such that the sections perpendicular to the axis of the transformer are substantially elliptical and of increasing eccentricity along this axis, provided that they are not take into account the ends of the major axis of these ellipses;
  • - ce transformateur comporte des moyens de focalisation guidant le faisceau d'électrons vers - des plaques collectrices, situées sur les parties voisines des extrémités du grand axe des ellipses constituant la section du transformateur.- This transformer includes focusing means guiding the electron beam towards - collector plates, located on the parts close to the ends of the major axis of the ellipses constituting the section of the transformer.

Par la demande de brevet britannique N° 2 083 691 on connaît un guide d'ondes de forme conique relié à la cavité résonante d'un gyrotron.By British patent application No. 2,083,691 there is known a conical waveguide connected to the resonant cavity of a gyrotron.

Par la demande de brevet européen n° 0 060 922, on connaît un transformateur de modes de propagation hyperfréquence, constitué par un guide d'onde, de section sensiblement elliptique, et d'ellipticité croissante le long de l'axe du transformateur.By European patent application No. 0 060 922, there is known a transformer of microwave propagation modes, constituted by a waveguide, of substantially elliptical section, and of increasing ellipticity along the axis of the transformer.

Cette demande de brevet concerne en fait une antenne qui reçoit un mode hybride, tel que le mode HE11-voir page 3, ligne 7 de cette demande - qui permet à l'antenne de rayonner. Cette antenne transforme ce mode en un autre mode qui améliore le rayonnement de l'antenne.This patent application in fact relates to an antenna which receives a hybrid mode, such as the HE 11 mode - see page 3, line 7 of this application - which allows the antenna to radiate. This antenna transforms this mode into another mode which improves the radiation of the antenna.

Il faut noter que dans notre demande de brevet le transformateur de modes est reliée à la cavité de révolution d'un gyrotron, qui lui fournit un mode complexe, tel que par exemple le mode TE12 de la figure 1, qui ne permet pas le rayonnement. Dans notre demande de brevet, le transformateur de modes assure le passage d'un mode du type TEon qui ne permet pas le rayonnement à un mode qui permet d'obtenir un rayonnement élevé, c'est-à-dire à un mode où le champ électrique est sensiblement parallèle à une direction donnée. Il ne nous semble pas du tout évident étant donné la fonction d'antenne du guide d'onde d'ellipticité croissante de la demande de brevet européen citée d'utiliser ce dispositif, en association avec un gyrotron, et avec une fonction différente.It should be noted that in our patent application the mode transformer is connected to the cavity of revolution of a gyrotron, which provides it with a complex mode, such as for example the TE 12 mode of FIG. 1, which does not allow the radiation. In our patent application, the mode transformer ensures the transition from a TE type mode on which does not allow radiation to a mode which allows to obtain a high radiation, that is to say a mode where the electric field is substantially parallel to a given direction. It does not seem obvious to us at all given the antenna function of the waveguide of increasing ellipticity of the cited European patent application to use this device, in association with a gyrotron, and with a different function.

D'autres objets, caractéristiques et résultats de l'invention ressortiront de la description suivante, donnée à titre d'exemple non limitatif et illustrée par les figures annexées qui représentent:

  • - les figures 1, 2 et 3, les lignes de champ électrique dans les sections droites de la cavité d'un gyrotron, d"un guide elliptique et d'un système constitué de deux plaques conductrices parallèles;
  • - la figure 4, un procédé permettant d'obtenir un transformateur de modes de section elliptique, d'excentricité croissante;
  • - la figure 5, le transformateur obtenu par le prcédé de la figure 4;
  • - la figure 6, une projection de coupes réalisées perpendiculairement à l'axe Oz sur le transformateur de la figure 5;
  • - les figures 7 et 8, deux schémas montrant la répartition du champ électrique dans la section d'un transformateur selon l'invention;
  • - la figure 9, la section droite d'un transformateur de modes de section elliptique, d'excentricité croissante comportant des volumes V1 et V2;
  • - la figure 10, une vue en perspective d'un mode de réalisation d'un transformateur selon l'invention comportant deux miroirs M, et M2 et deux zones collectrices C, et CZ;
  • - les figures 11 à 14, les lignes de champ électrique dans la section droite de la cavité du gyrotron et d'un transformateur selon l'invention constitué de deux miroirs M, et Mz;
  • - les figures 15 et 16, les éléments faisant suite au transformateur selon l'invention et permettant d'obtenir respectivement deux ondes planes et une onde plane.
Other objects, characteristics and results of the invention will emerge from the following description, given by way of nonlimiting example and illustrated by the appended figures which represent:
  • - Figures 1, 2 and 3, the electric field lines in the cross sections of the cavity of a gyrotron, of an elliptical guide and of a system consisting of two parallel conductive plates;
  • - Figure 4, a method for obtaining a transformer of elliptical section modes, of increasing eccentricity;
  • - Figure 5, the transformer obtained by the process of Figure 4;
  • - Figure 6, a projection of sections made perpendicular to the axis Oz on the transformer of Figure 5;
  • - Figures 7 and 8, two diagrams showing the distribution of the electric field in the section of a transformer according to the invention;
  • - Figure 9, the cross section of a transformer of elliptical section modes, of increasing eccentricity comprising volumes V 1 and V 2 ;
  • - Figure 10, a perspective view of an embodiment of a transformer according to the invention comprising two mirrors M, and M 2 and two collecting zones C, and C Z ;
  • - Figures 11 to 14, the electric field lines in the cross section of the cavity of the gyrotron and of a transformer according to the invention consisting of two mirrors M, and M z ;
  • - Figures 15 and 16, the elements following the transformer according to the invention and allowing to obtain respectively two plane waves and a plane wave.

Sur les différentes figures, les mêmes repères désignent les mêmes éléments, mais, pour des raisons de clarté, les cotes et proportions des divers éléments ne sont pas respectées.In the different figures, the same references designate the same elements, but, for reasons of clarity, the dimensions and proportions of the various elements are not observed.

On va expliquer le fonctionnement du transformateur de modes selon l'invention en se référant aux figures 1, 2 et 3.We will explain the operation of the mode transformer according to the invention with reference to Figures 1, 2 and 3.

Sur la figure 1, on a représenté les lignes de champ électrique dans la section droite circulaire de la cavité 1 d'un gyrotron, dans le cas où un mode TEo2 est établi dans cette cavité. Les cercles en trait plein indiquent les zones où le champ électrique est maximum et les cercles en pointillés indiquent les zones où le champ électrique est nul. Ce mode TE02 circulaire et symétrique ne permet pas le rayonnement.In Figure 1, there is shown the electric field lines in the circular cross section of the cavity 1 of a gyrotron, in the case where a TE o2 mode is established in this cavity. The solid circles indicate the areas where the electric field is maximum and the dotted circles indicate the areas where the electric field is zero. This circular and symmetrical TE 02 mode does not allow radiation.

La figure 2 montre la répartition des lignes de champ électrique dans la section droite d'un guide d'onde 2 de section elliptique placé à la suite de la cavité d'un gyrotron où est établi un mode TEo2 comme sur la figure 1. On désigne par a et b le grand axe et le petit axe de l'ellipse. Sur la figure 2, le petit axe b égale deux fois le rayon intérieur R de la cavité du gyrotron.Figure 2 shows the distribution of electric field lines in the cross section of a guide wave 2 of elliptical section placed following the cavity of a gyrotron where a TE o2 mode is established as in Figure 1. We designate by a and b the major axis and the minor axis of the ellipse. In FIG. 2, the minor axis b twice equals the interior radius R of the gyrotron cavity.

On constate sur la figure 2 qu'il y a une modification importante de la forme des lignes de champ électrique par rapport à la figure 1. Les lignes de champ électrique deviennent sensiblement parallèles à la direction x indiquée sur la figure 2. On peut noter que vers les deux extrémités du grand axe, le champ électrique est faible.We see in Figure 2 that there is a significant change in the shape of the electric field lines compared to Figure 1. The electric field lines become substantially parallel to the direction x indicated in Figure 2. We can note that towards the two ends of the major axis, the electric field is weak.

La figure 3 montre la répartition des lignes de champ électrique dans la section droite d'un système constitué de-deux plaques conductrices parallèles, portant la référence 3. La distance d entre les plaques est prise égale à deux fois le rayon R de la cavité du gyrotron. On constate que les lignes de champ électrique sont parallèles à la direction x.Figure 3 shows the distribution of the electric field lines in the cross section of a system consisting of two parallel conductive plates, bearing the reference 3. The distance d between the plates is taken equal to twice the radius R of the cavity of the gyrotron. It can be seen that the electric field lines are parallel to the x direction.

Le transformateur de modes selon l'invention permet de passer du mode TEo2 établi dans la cavité de section circulaire d'un gyrotron et qui ne permet pas le rayonnement à un mode où le champ électrique est sensiblement parallèle à la direction x en utilisant un guide d'onde, de section sensiblement elliptique, et d'excentricité croissante, et qui permet un rayonnement important.The mode transformer according to the invention makes it possible to pass from the TE o2 mode established in the circular section cavity of a gyrotron and which does not allow radiation to a mode where the electric field is substantially parallel to the direction x by using a waveguide, of substantially elliptical section, and of increasing eccentricity, and which allows a significant radiation.

On définit l'excentricité d'une ellipse par la relation suivante:

Figure imgb0001
We define the eccentricity of an ellipse by the following relation:
Figure imgb0001

L'excentricité est nulle lorsque a égale b, c'est-à-dire lorsque l'ellipse devient un cercle.The eccentricity is zero when a equals b, i.e. when the ellipse becomes a circle.

Lorsque le grand axe a tend vers l'infini l'excentricité de l'ellipse tend vers 1.When the major axis has tends towards infinity the eccentricity of the ellipse tends towards 1.

Le transformateur de modes selon l'invention est constitué par un guide d'onde de section sensiblement elliptique, et d'excentricité croissante, c'est-à-dire que la section droite de-ce transformateur a la forme d'une ellipse dont le grand axe a augmente et tend vers la section droite de la figure 3 qui est celle d'un système constitué de deux plaques parallèles qui peut être assimilée à la section droite d'une ellipse d'excentricité égale à 1. Dans le transformateur de modes selon l'invention, les lignes de champ ont la répartition indiquée sur la figure 2 puis tendent vers la répartition de la figure 3, c'est-à-dire que lorsque l'excentricité de l'ellipse croît, les lignes de champ deviennent de plus en plus parallèles à la direction x.The mode transformer according to the invention consists of a waveguide of substantially elliptical section, and of increasing eccentricity, that is to say that the cross section of this transformer has the shape of an ellipse whose the major axis a increases and tends towards the cross section of FIG. 3 which is that of a system made up of two parallel plates which can be assimilated to the cross section of an ellipse with eccentricity equal to 1. In the transformer of modes according to the invention, the field lines have the distribution indicated in Figure 2 and then tend towards the distribution of Figure 3, that is to say that when the eccentricity of the ellipse increases, the field lines become more and more parallel to the x direction.

Ce qui vient d'être exposé pour le mode TEo2 s'applique de la même façon à tous les modes TEon. On verra dans la suite de la description que le transformateur de modes selon l'invention s'applique à d'autres modes complexes que les modes TEon.What has just been explained for TE o2 mode applies in the same way to all TE on modes. It will be seen in the following description that the mode transformer according to the invention applies to other complex modes than the TE on modes.

Dans la cavité du gyrotron pour le mode TE12, la fréquence f et le rayon R de la cavité sont liés par la relation suivante:

Figure imgb0002
où c est la vitesse de la lumière. Cette relation exprime que la fréquence est très voisine de la fréquence de coupure.In the TE 12 mode gyrotron cavity, the frequency f and the radius R of the cavity are linked by the following relation:
Figure imgb0002
 where c is the speed of light. This relation expresses that the frequency is very close to the cutoff frequency.

La fréquence de coupure f3 du système constitué de deux plaques conductrices parallèles représenté sur la figure 3 s'écrit:

Figure imgb0003
The cut-off frequency f 3 of the system made up of two parallel conducting plates represented on figure 3 is written:
Figure imgb0003

Dans le cas où la distance d est égale à 2R, on obtient la relation suivante:

Figure imgb0004
In the case where the distance d is equal to 2R, we obtain the following relation:
Figure imgb0004

Le système de la figure 3 se trouve au-dessus de la fréquence de coupure. On obtient alors pour la vitesse de phase VØ et la longueur d'onde guidée λg:

Figure imgb0005
et λg = 2,2477.λ.The system in Figure 3 is above the cutoff frequency. We then obtain for the phase speed V Ø and the guided wavelength λ g :
Figure imgb0005
 and λg = 2.2477.λ.

On constate donc que lorsque le petit axe b de l'ellipse est constant, on passe d'une onde stationnaire dans le gyrotron à une onde progressive dans le transformateur selon l'invention.It can therefore be seen that when the minor axis b of the ellipse is constant, we pass from a standing wave in the gyrotron to a traveling wave in the transformer according to the invention.

Lorsque le petit axe b de l'ellipse augmente le long de l'axe z, perpendiculaire aux axes x et y, l'onde propage plus vite l'énergie car la fréquence de coupure diminue. En réglant cette augmentation, on peut donc modifier l'impédance de rayonnement présentée par le transformateur selon l'invention au guide ou à la cavité circulaire auquel il est relié. C'est ce qui se passe dans les cornets de section circulaire qui sont d'ordinaire reliés à la cavité d'un gyrotron et dont le rayon croît avec la coordonnée axiale z.When the small b axis of the ellipse increases along the z axis, perpendicular to the x and y axes, the wave propagates energy faster because the cutoff frequency decreases. By adjusting this increase, it is therefore possible to modify the impedance of radiation presented by the transformer according to the invention to the guide or to the circular cavity to which it is connected. This is what happens in the horns of circular section which are usually connected to the cavity of a gyrotron and whose radius increases with the axial coordinate z.

Le transformateur selon l'invention peut être réalisé en effectuant par électrolyse un dépôt métallique sur une matrice, comme cela se fait pour réaliser des guides d'ondes.The transformer according to the invention can be produced by carrying out a metallic deposit on a matrix by electrolysis, as is done to produce waveguides.

La figure 4 illustre un autre procédé permettant d'obtenir un transformateur de modes de section elliptique, d'excentricité croissante.FIG. 4 illustrates another method making it possible to obtain a transformer of modes of elliptical section, of increasing eccentricity.

On part d'un tronc de cône 4 dont le rayon de la petite section 5 égale R. On scie ce tronc de cône selon deux plans P, et P2 passant par un même diamètre D de la petite section 5. On isole ainsi deux portions 6 en forme de coins qui ont été hachurées sur la figure 4 et que l'on élimine. On brase ensuite les deux parties du tronc de cône 7 restantes qui présentent une flèche R, sur la grande section 8 du tronc de cône primitif.We start from a truncated cone 4 whose radius of the small section 5 equals R. We saw this truncated cone along two planes P, and P 2 passing through the same diameter D of the small section 5. We thus isolate two wedge-shaped portions 6 which have been hatched in FIG. 4 and which are eliminated. The two remaining parts of the truncated cone 7 which have an arrow R are then brazed on the large section 8 of the original truncated cone.

La figure 5 représente un transformateur de modes 9 qui est obtenu de cette façon.FIG. 5 represents a mode transformer 9 which is obtained in this way.

La figure 6 est une projection de coupes réalisées perpendiculairement à l'axe Oz sur le cornet représenté sur la figure 5. Dans l'exemple des figures 5 et 6 le petit axe b de l'ellipse, dirigé selon l'axe Oy augmente légèrement le long de l'axe Oz.Figure 6 is a projection of sections made perpendicular to the Oz axis on the horn shown in Figure 5. In the example of Figures 5 and 6 the small axis b of the ellipse, directed along the axis Oy slightly increases along the Oz axis.

Le cornet représenté sur la figure 5 constitue une bonne réalisation du transformateur de modes car on montre qu'au fur et à mesure que l'excentricité d'une ellipse augmente, l'énergie électromagnétique se concentre entre deux hyperboles H, et Hz ayant F, et Fz pour foyers. On a représenté sur la figure 7 une ellipse avec ses deux foyers F, et F2 et les deux hyperboles H1 et HZ. Si les dimensions du guide sont grandes devant la longueur d'onde, la répartition de la densité d'énergie électrique E2 est voisine d'une fonction gaussienne comme cela est représenté sur la figure 8.The horn shown in Figure 5 is a good embodiment of the mode transformer because it is shown that as the eccentricity of an ellipse increases, the energy electromagnetic is concentrated between two hyperbolas H, and H z having F, and F z for foci. FIG. 7 shows an ellipse with its two foci F, and F 2 and the two hyperbolas H 1 and H Z. If the dimensions of the guide are large compared to the wavelength, the distribution of the electrical energy density E 2 is close to a Gaussian function as shown in FIG. 8.

L'examen des figures 7 et 8 montre que l'on peut sans perturbation modifier les parois du guide et même les espaces hachurés limités par les hyperboles H, et H2 de la figure 7. Dans le transformateur selon l'invention, on peut considérer pour donner l'ordre de grandeur de l'ellipticité que dans la section finale du transformateur, on a quelques longueurs d'onde entre les deux foyers F, et FZ.Examination of FIGS. 7 and 8 shows that it is possible without disturbance to modify the walls of the guide and even the hatched spaces limited by the hyperbolas H, and H 2 of FIG. 7. In the transformer according to the invention, it is possible to consider to give the order of magnitude of the ellipticity that in the final section of the transformer, there are some wavelengths between the two foci F, and F Z.

Un transformateur de modes, constitué d'un guide de section elliptique, d'excentricité croissante, peut donc être réalisé par le cornet de la figure 5, constitué de deux parties de cône de révolution.A mode transformer, consisting of a guide of elliptical section, of increasing eccentricity, can therefore be produced by the horn of FIG. 5, consisting of two parts of cone of revolution.

Les deux demi-cornets 7 peuvent provenir de deux troncs de cône différents. Il faut obtenir un cornet comportant deux parties de courbure décroissante et dont la distance à l'axe z croît moins vite que le rayon de courbure, ce qui jouera le rôle d'ellipses d'excentricité croissante.The two half-horns 7 can come from two different truncated cones. It is necessary to obtain a horn comprising two parts of decreasing curvature and whose distance to the axis z increases less quickly than the radius of curvature, which will play the role of ellipses of increasing eccentricity.

Quelle que soit la façon dont il est fabriqué, le transformateur selon l'invention peut comporter sur les parties voisines des extrémités du grand axe des cavités dans lesquelles on dispose un matériau absorbant qui absorbe tout autre mode que le mode désiré. La figure 9 représente la section droite d'un transformateur de modes obtenu en brasant deux parties de tronc de cône. On a creusé les parties voisines des extrémités du grand axe pour obtenir les volumes allongés V1 et Vz qui renferment un matériau absorbant 10. Comme il n'y a que très peu d'énergie emmagasinée près des extrémités du grand axe, les volumes V, et V2 ne perturbent pas le fonctionnement du transformateur de modes.Whatever the way in which it is manufactured, the transformer according to the invention may comprise on the parts close to the ends of the long axis of the cavities in which there is an absorbent material which absorbs any mode other than the desired mode. FIG. 9 represents the cross section of a mode transformer obtained by brazing two parts of truncated cone. The parts close to the ends of the major axis were dug to obtain the elongated volumes V 1 and V z which contain an absorbent material 10. Since there is only very little energy stored near the ends of the major axis, the volumes V, and V 2 do not disturb the operation of the mode transformer.

Sur la figure 9, on a représenté les lignes de champ obtenues à partir d'un mode TR02 dans la cavité circulaire du gyrotron. On constate que les lignes de champ électrique sont sensiblement parallèles à l'axe x, et donc au grand axe de l'ellipse a.In FIG. 9, the field lines obtained from a TR 02 mode are shown in the circular cavity of the gyrotron. It can be seen that the electric field lines are substantially parallel to the x axis, and therefore to the major axis of the ellipse a.

La figure 10 montre un mode de réalisation du transformateur selon l'invention. La figure 10 est une vue en perspective où l'on voit, sur la partie gauche un gyrotron 11, qui est représenté symboliquement par un cylindre, suivi par le transformateur de modes selon l'invention 9 qui est constitué de deux miroirs M, et MZ. Ces deux miroirs sont concaves, Ils sont disposés de part et d'autre de l'axe Oz, perpendiculairement à l'axe y, et se font face. Ces deux miroirs sont contenus dans une enceinte à vide qui n'est pas représentée sur la figure 10.FIG. 10 shows an embodiment of the transformer according to the invention. FIG. 10 is a perspective view where we see, on the left side a gyrotron 11, which is symbolically represented by a cylinder, followed by the mode transformer according to the invention 9 which is made up of two mirrors M, and M Z. These two mirrors are concave, They are arranged on either side of the Oz axis, perpendicular to the y axis, and face each other. These two mirrors are contained in a vacuum enclosure which is not shown in FIG. 10.

Dans la partie droite de la figure 10, on a représenté en pointillés le contour de la fenêtre 12 qui assure l'étanchéité au vide de l'enceinte contenant les miroirs M, et M2.In the right-hand part of FIG. 10, the outline of the window 12 is shown in dotted lines which ensures the vacuum tightness of the enclosure containing the mirrors M, and M 2 .

Le transformateur selon l'invention peut se trouver comme c'est le cas sur la figure 10, dans la même enceinte à vide que le gyrotron. Il peut aussi être placé à la sortie d'un gyrotron de structure habituelle.The transformer according to the invention can be found, as is the case in FIG. 10, in the same vacuum enclosure as the gyrotron. It can also be placed at the exit of a gyrotron of usual structure.

On choisit la forme des miroirs M1 et M2 pour que les sections perpendiculaires à l'axe z du transformateur selon l'invention ainsi réalisé soient sensiblement elliptiques et d'excentricité croissante le long de l'axe Oz, à condition de ne pas tenir compte des extrémités du grand axe de ces ellipses où l'on a vu que le champ électrique est très faible.The shape of the mirrors M 1 and M 2 is chosen so that the sections perpendicular to the z axis of the transformer according to the invention thus produced are substantially elliptical and of increasing eccentricity along the oz axis, provided that not take into account the ends of the major axis of these ellipses where we have seen that the electric field is very weak.

Le transformateur selon l'invention peut assurer le passage, d'autres modes que les modes TEon, à un mode où le champ électrique est sensiblement parallèle à une direction donnée.The transformer according to the invention can ensure the passage, modes other than the TE modes is in a mode where the electric field is substantially parallel to a given direction.

Les figures 11 et 13 montrent les lignes de champ électrique dans la section droite de la cavité 1 du gyrotron lorsqu'un mode TE12 et un mode TE22 est établi dans cette cavité.Figures 11 and 13 show the electric field lines in the cross section of cavity 1 of the gyrotron when a TE mode 12 and a TE mode 22 is established in this cavity.

Les figures 12 et 14 montrent les lignes de champ électrique dans la section droite du transformateur selon l'invention constitué des deux miroirs M, et M2 qui est placé à la suite de la cavité d'un gyrotron où est établi respectivement le mode TE12 de la figure 11 et le mode TE22 de la figure 13. On obtient dans le transformateur selon l'invention un mode TEc et un mode TEd de guide ouvert. On constate que les lignes de champ électrique sont dirigées sensiblement selon l'axe x et présentent 3 et 4 alternances successives entre M1 et M2.Figures 12 and 14 show the electric field lines in the cross section of the transformer according to the invention consisting of the two mirrors M, and M 2 which is placed following the cavity of a gyrotron where the TE mode is established respectively. 12 of FIG. 11 and the TE mode 22 of FIG. 13. A TE c mode and a TE d mode of open guide are obtained in the transformer according to the invention. It can be seen that the electric field lines are directed substantially along the x axis and have 3 and 4 successive alternations between M 1 and M 2 .

Un des problèmes qui se pose dans le domaine du gyrotron est de séparer le circuit de sortie du collecteur du faisceau d'électrons. La figure 10 propose une solution à ce problème.One of the problems which arises in the field of gyrotron is to separate the collector output circuit from the electron beam. Figure 10 suggests a solution to this problem.

Lorsqu'un s'éloigne du gyrotron, le champ magnétique continu, crée par un solénoïde de focalisation 21 disposé autour du gyrotron, décroît, le faisceau d'électrons diverge et vient frapper les parois du transformateur 9.When one moves away from the gyrotron, the continuous magnetic field, created by a focusing solenoid 21 placed around the gyrotron, decreases, the electron beam diverges and strikes the walls of the transformer 9.

Pour éviter l'impact des électrons sur les miroirs M, et M2, on dispose autour du transformateur des moyens de focalisation qui dirigent le faisceau d'électrons sur des plaques collectrices Ci et C2. Ces plaques sont disposées de part et d'autre de l'axe Oz, perpendiculairement à l'axe x, et se font face. Elles sont donc situées sur les parties voisines des extrémités du grand axe des ellipses constituant la section du transformateur. Elles sont contenues dans l'enceinte à vide renfermant les miroirs M1 et M2.To avoid the impact of the electrons on the mirrors M, and M 2 , focusing means are arranged around the transformer which direct the electron beam onto collector plates Ci and C 2 . These plates are arranged on either side of the Oz axis, perpendicular to the x axis, and face each other. They are therefore located on the parts close to the ends of the long axis of the ellipses constituting the section of the transformer. They are contained in the vacuum enclosure containing the mirrors M 1 and M 2 .

Sur la figure 10, on a représenté symboliquement deux trajectoires électroniques aboutissant aux plaques collectrices C1 et C2.In FIG. 10, two electronic paths have been symbolically represented leading to the collector plates C 1 and C 2 .

Les moyens de focalisation, qui ne sont pas représentés sur la figure 10, peuvent être constitués par exemple de deux enroulements allongés plaqués le long du transformateur 9 à la manière des bobines de déflexion des tubes de télévision, et reliés à une source de tension continue. Ces enroulements sont parcourus par des courants tournant en sens inverse autour de l'axe x.The focusing means, which are not shown in FIG. 10, can consist for example of two elongated windings pressed along the transformer 9 in the manner of the deflection coils of the television tubes, and connected to a DC voltage source . These windings are traversed by currents rotating in opposite directions around the x axis.

On peut prévoir des zones collectrices dans les autres modes de réalisation du transformateur selon l'invention lorsque le transformateur est placé à l'intérieur de l'enceinte à vide. Par exemple, dans le mode de réalisation de la figure 9 les volumes VI et V2 peuvent servir à collecter le faisceau d'électrons.Collector zones can be provided in the other embodiments of the transformer according to the invention when the transformer is placed inside the vacuum enclosure. For example, in the embodiment of Figure 9 the volumes V I and V2 can be used to collect the electron beam.

On va montrer maintenant comment on peut passer d'un mode où le champ électrique est sensiblement parallèle à une direction donnée à une onde plane.We will now show how we can go from a mode where the electric field is substantially parallel to a given direction to a plane wave.

Les configurations du champ électrique représentées sur les figures 2, 3, 9, 12 et 14 ont en commun les caractéristiques suivantes. Il y a propagation dans la direction z. Dans la direction y, il y a une onde stationnaire et dans la direction x, il y a une variation lente d'amplitude, sans variation de phase.The configurations of the electric field represented in FIGS. 2, 3, 9, 12 and 14 have in common the following characteristics. There is propagation in the z direction. In the y direction there is a standing wave and in the x direction there is a slow variation in amplitude, with no phase variation.

Ce système d'ondes peut être représenté par deux ondes planes croisées O1 et O2 dont on a figuré les trajets sur la figure 15, dans le plan yOz, dans un tronçon de guide d'ondes 13 faisant suite au transformateur selon l'invention et comportant deux parois parallèles à l'axe Oz. Ce tronçon de guide d'ondes a la même section que la section finale du transformateur et a une section constante selon l'axe Oz. On a représenté sur la partie droite de la figure 15 que lorsque le guide est interrompu, l'optique géométrique indique que l'on obtient deux faisceaux d'ondes planes 14 et 15 de directions différentes.This wave system can be represented by two crossed plane waves O 1 and O2, the paths of which have been shown in FIG. 15, in the plane yOz, in a section of waveguide 13 following the transformer according to the invention and having two walls parallel to the Oz axis. This waveguide section has the same section as the final section of the transformer and has a constant section along the axis Oz. It has been shown on the right-hand side of FIG. 15 that when the guide is interrupted, the geometric optics indicate that two beams of plane waves 14 and 15 of different directions are obtained.

Ces faisceaux sont naturellement sujets à la diffraction, mais celle-ci est d'autant moins importante qu'il y a plus d'ondes planes dans la largeur h des faisceaux.These beams are naturally subject to diffraction, but this is all the less important as there are more plane waves in the width h of the beams.

On peut établir la relation:

Figure imgb0006
où q est le nombre d'alternances spatiales dans la section droite du transformateur, selon la direction y et où a est l'angle d'inclinaison des ondes O1 et O2 sur l'axe Oz.We can establish the relation:
Figure imgb0006
 where q is the number of spatial alternations in the cross section of the transformer, in the direction y and where a is the angle of inclination of the waves O 1 and O 2 on the axis Oz.

Les deux faisceaux 14 et 15 restent parallèles avant de diverger par diffraction après une distance LR, dite distance de Rayleigh, qui est égale à:

Figure imgb0007
The two beams 14 and 15 remain parallel before diverging by diffraction after a distance L R , called Rayleigh distance, which is equal to:
Figure imgb0007

Pour un mode dans lequel q égale 10 une longueur d'onde À de à 2 mm, un angle a de 10°, on obtient:

Figure imgb0008
For a mode in which q equals 10 a wavelength λ of 2 mm, an angle a of 10 °, we obtain:
Figure imgb0008

On peut donc rayonner des ondes essentiellement planes sur une grande distance à condition de faire suivre le transformateur selon l'invention par un tronçon de guides d'ondes ayant la même section que la section finale du transformateur et ayant une section constante selon l'axe Oz.It is therefore possible to radiate essentially plane waves over a large distance provided that the transformer according to the invention is followed by a section of waveguides having the same section as the final section of the transformer and having a constant section along the axis. Oz.

On peut aussi obtenir un seul faisceau parallèle dès la sortie du tube en utilisant des miroirs placés à l'intérieur du tube comme cela va être expliqué en se référant à la figure 16.It is also possible to obtain a single parallel beam as soon as it leaves the tube by using mirrors placed inside the tube as will be explained with reference to FIG. 16.

La figure 16 est une section longitudinale selon l'axe Oz qui montre:

  • - un gyrotron 11, son canon à électrons comportant une cathode 16, et une anode accélératrice 17, sa cavité résonnante 1, entourée par le solénoïde de focalisation du faisceau 21;
  • - un transformateur selon l'invention 9, dont la section est sensiblement elliptique et d'excentricité croissante et qui peut comporter des plaques C, et C2, collectant le faisceau d'électrons.
  • - un tronçon de guide d'onde 13 ayant la même section que la section finale du transformateur et dont la section est constante selon l'axe z;
  • - une dernière partie 18 qui permet l'obtention d'un seul faisceau parallèle 19 au lieu des deux faisceaux 14 et 15 de la figure 15.
FIG. 16 is a longitudinal section along the axis Oz which shows:
  • - A gyrotron 11, its electron gun comprising a cathode 16, and an accelerating anode 17, its resonant cavity 1, surrounded by the beam focusing solenoid 21;
  • - A transformer according to the invention 9, the section of which is substantially elliptical and of increasing eccentricity and which may include plates C, and C 2 , collecting the electron beam.
  • - A waveguide section 13 having the same section as the final section of the transformer and whose section is constant along the axis z;
  • - a last part 18 which makes it possible to obtain a single parallel beam 19 instead of the two beams 14 and 15 of FIG. 15.

Cette partie 18 comporte deux miroirs M3 et M4. L'inclinaison de ces deux miroirs est choisie pour que le miroir M3 reçoive l'onde plane 14 et la réfléchisse verticalement sur la figure 16 et pour que le miroir M4 reçoive l'onde plane 15 et la réfléchisse aussi verticalement. Il faut aussi que les ondes réfléchies par les deux miroirs ne se perturbent pas. Sur la figure, le miroir M3 est parallèle à l'onde 15.This part 18 comprises two mirrors M 3 and M 4 . The inclination of these two mirrors is chosen so that the mirror M 3 receives the plane wave 14 and reflects it vertically in FIG. 16 and so that the mirror M 4 receives the plane wave 15 and also reflects it vertically. The waves reflected by the two mirrors must also not be disturbed. In the figure, the mirror M 3 is parallel to the wave 15.

La partie 18 se termine par une fenêtre 20 étanche au vide et transparente au rayonnement. On peut donner aux miroirs M3 et M4 une courbure sphérique ou cylindrique de manière à compenser sur une certaine longueur la diffraction du faisceau issu du tube par la fenêtre.Part 18 ends with a window 20 which is vacuum tight and transparent to radiation. Mirrors M 3 and M 4 can be given a spherical or cylindrical curvature so as to compensate over a certain length for the diffraction of the beam coming from the tube through the window.

La partie 18 peut aussi permettre l'obtention d'un seul faisceau parallèle tout en n'utilisant qu'un seul miroir courbe, plus encombrant que les deux miroirs M, et M2.Part 18 can also allow a single parallel beam to be obtained while using only a single curved mirror, more bulky than the two mirrors M, and M 2 .

Le mode de réalisation de la figure 16 permet de rendre l'axe principal du tube Oz vertical, ce qui . est préférable pour sa tenue mécanique, alors que le faisceau parallèle obtenu est horizontal ce qui est pratique pour les utilisateurs.The embodiment of Figure 16 makes the main axis of the Oz tube vertical, which. is preferable for its mechanical strength, while the parallel beam obtained is horizontal, which is practical for users.

Claims (3)

1. A transformer for propagation modes in the microwawe region, comprising a wawe guide with a substantially elliptical cross section (2) and with an eccentricity (e) increasing along the axis (z) of the transformer (9), said transformer ensuring the passage in a mode where the electrical field is substantially parallel to a given direction (Oz), characterized in that:
-the transformer is connected with the cavity of a gyrotron, which supplies it with a complex mode of the TRon type, the transformer being placed in the first vacuum enclosure of the gyrotron,
- the transformer is constituted by two concave mirrors (M, and M2) which are face to face, the form of the mirrors being such that the cross sections perpendicular to the axis (z) of the transformer (9) are substantially elliptical and with an eccentricity (e) increasing along this axis (Oz) with the condition that the extremities of the major axis of these ellipses is ignored, and
- the transformer comprises focussing means guiding the electron beam towards to collecting plates (C, and CZ) placed on the neighboring parts of the extremities of the major axis (a) of the ellipses constituting the cross section of the transformer (9).
2. The transformer as claimed in claim 1, characterized in that the minor axis of the ellipse (b) is constant.
3. The transformer as claimed in claim 1, characterized in that the minor axis of the ellipse (b) increases in size along the axis (Oz) of the transformer.
EP84400542A 1983-03-18 1984-03-16 Microwave propagation-mode transformer Expired EP0122834B1 (en)

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FR8304484A FR2542928B1 (en) 1983-03-18 1983-03-18 MICROPHONE PROPAGATION TRANSFORMER
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FR2542928A1 (en) 1984-09-21
FR2542928B1 (en) 1985-10-04
DE3480626D1 (en) 1990-01-04
US4636689A (en) 1987-01-13
EP0122834A1 (en) 1984-10-24

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