EP0018261B1 - Wide-band waveguide with double polarisation - Google Patents

Wide-band waveguide with double polarisation Download PDF

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Publication number
EP0018261B1
EP0018261B1 EP80400448A EP80400448A EP0018261B1 EP 0018261 B1 EP0018261 B1 EP 0018261B1 EP 80400448 A EP80400448 A EP 80400448A EP 80400448 A EP80400448 A EP 80400448A EP 0018261 B1 EP0018261 B1 EP 0018261B1
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Prior art keywords
wave guide
section
waveguide
symmetry
mode
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German (de)
French (fr)
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EP0018261A1 (en
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Jacky Tourneur
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/16—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion
    • H01P1/161—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion sustaining two independent orthogonal modes, e.g. orthomode transducer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P3/00—Waveguides; Transmission lines of the waveguide type
    • H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
    • H01P3/06—Coaxial lines

Definitions

  • the present invention relates to broadband microwave waveguides, allowing propagation under identical conditions of cutoff frequency and impedance of two electromagnetic waves of polarization, or direction of the electric field, orthogonal.
  • Bandwidth is defined by the ratio: where ⁇ c 2 and ⁇ c 1 are the cutoff wavelengths of the fundamental mode and the first higher order mode.
  • the constraint of the double polarization imposes on the cross section of the guide to admit the longitudinal axis of the wave guide as an axis of symmetry of order 4n where n is any integer ⁇ 1, a symmetry of order 4n with respect to to this longitudinal axis being a symmetry such as a rotation around this same axis of the section of the waveguide by an angle of does not change the properties of the waveguide, the polarizations of this waveguide being generally unchanged.
  • a determined mode propagates only if there are the conditions necessary for its excitation, the TE 20 mode, asymmetrical mode, not appearing in a waveguide where radio propagation symmetry conditions are maintained, even beyond the TE 20 cutoff frequency.
  • a bending of the guide capable of creating an asymmetry, causes the appearance of the TE zo mode.
  • a guide can therefore only be used, outside of its bandwidth, under very specific conditions of mechanical and / or radio symmetry.
  • FR-A-2 116 441 is a broadband, double polarization waveguide in which the cross section is cruciform.
  • This waveguide consists of a hollow conductor, of rectangular or square section, on the internal face of which are arranged four corners situated on the bisectors of the main axes of propagation in order to obtain the transmission of the wave injected with particularly low depreciation.
  • the present invention aims to significantly increase the bandwidth of a waveguide in order to obtain bandwidths greater than 60%
  • the subject of the invention is a wideband, double polarization waveguide consisting of a hollow conductor of polygonal section having with respect to its center of symmetry, a symmetry of order 4n, in which n is an integer, and two main axes of propagation, mutually orthogonal, the internal face of this hollow conductor is provided four notches whose longitudinal planes of symmetry are located along the bisectors of the main axes of propagation and this waveguide comprises a central conductive core of polygonal shape, the section of this central core and that of the hollow conductor being homothetic with respect to the center of symmetry.
  • the wide-band double polarization waveguide object of the invention, comprises a hollow conductor of polygonal section 1 having, with respect to a center of symmetry C, a symmetry of order 4n where n is any integer.
  • the waveguide according to the invention contains inside the hollow conductor of polygonal section a plurality of conductive steps 2, the section of which determines, with the polygonal section, a propagation section of the waveguide.
  • Each of the steps 2 is arranged on the internal face of the sides of the hollow conductor, according to a symmetry of order 4 with respect to the center of symmetry C.
  • the longitudinal plane of symmetry of each of the steps is oriented, in the propagation section of the guide in the direction of the bisectors of the main axes of the waveguide.
  • the main axes of the waveguide are represented by the axes X'X, and Y'Y, their orientation corresponds respectively to the direction of the electric fields of the propagation modes TE lQ and TE oi , for the guide wave considered.
  • the longitudinal plane of symmetry of each step has not been shown so as not to overload the figure.
  • the waveguide according to the invention comprises, on the other hand, inside the hollow conductor of polygonal section, a central conductive core 3, the section of which has with respect to the center of symmetry C the same symmetry d order 4n, the sections of the central conductive core and of the hollow conductor of polygonal section being homothetic with respect to this center of symmetry C.
  • the hollow conductor of polygonal section has a square side section 2a.
  • This section presents, with respect to the center of symmetry C, a symmetry of order 4.
  • the hollow conductor comprises, inside each dihedral angle formed by two consecutive sides of the square section, a conductive step 2 of also square section on the W side.
  • the four steps arranged in the section of the hollow conductor, at the end of the diagonals of this section, determine, with the square section of the hollow conductor, a propagation section of the waveguide having, with respect to this same center of symmetry C, a symmetry of order 4.
  • the hollow conductor of polygonal section comprises, on the other hand, a central conductive core 3 whose square section of side 2k has, with respect to this same center of symmetry C, the same order 4 symmetry.
  • the diagonals of the square section of the hollow conductor 1 and the diagonals of the section of the central conductive core are combined.
  • FIGS. 2a and 2b The operation of the waveguide, object of the invention, is as follows taking into account FIGS. 2a and 2b in which FIG. 2a comprises a system of axes whose ordinates are graduated in standard cut-off frequency or ratio of dimension of the guide, according to FIG. 1, at the cut-off wavelength of this same guide, the normalized cut-off frequency being noted and whose abscissae are graduated in relation to the dimension on the side of the step W to the same dimension 2a of the waveguide.
  • FIG. 2a represents the variations in the cutoff frequencies of the main propagation modes such as the TE 11 , TM 11, TE 201 and TE 10 modes. In the same way, FIG.
  • FIG. 2b represents, on a system of axes, respectively on the ordinate, the normalized cut-off frequencies of the waveguide, the ordinate axis being graduated in value of the ratio where 2a represents the dimension of the side of the square section of the waveguide, according to FIG. 1, and ⁇ c the corresponding cut-off wavelength, as a function of the ratio of the dimension of the central conducting core of square section of side 2k related to this same dimension of the square section waveguide and side 2a.
  • FIG. 2b represents the different standardized cut-off frequencies for the main modes such as TM 11 , TE 201 , TE 11 , and TE 10 .
  • FIG. 2a and 2b respectively show that, in the case of the square guide comprising the only steps within each dihedral angle formed by two consecutive sides of the square section, the TM 11 mode limits the bandwidth as long as the ratio remains less than 0.22, the TE 201 mode becoming substantially the first parasitic mode for higher values of this ratio.
  • FIG. 2b shows that, in the case of the square section guide comprising a central core of also square section, the only higher order mode limiting the bandwidth is the TE 11 mode whose cut-off frequency depends little on the report According to the ivention, the simultaneous use of the propagation characteristics of the guide alone comprising the steps, as shown in FIG.
  • the bandwidth of the guide thus produced is a function of the ratios W and K , geometrical parameters of the guide according to the invention. For a determined K value, there is an optimal W ratio for which the bandwidth is maximum.
  • the value of the bandwidth BW obtained by the implementation of a waveguide according to the invention as shown in FIG. 1, is given in the following table, as a function of the values of the ratios K and W. aa
  • Figures 3a and 3b show for different values of the ratio k the variation of the normalized cut-off frequency , ratio of the half-dimension of the square section waveguide to the cut-off wavelength of the guide, as a function of the ratio W , dimension of the side of the section of the square step related to this same half-dimension a of the waveguide section.
  • the waveguide according to the invention makes it possible to obtain a higher bandwidth than that of the guides hitherto used to solve similar problems.
  • the bandwidth of the guide according to the invention, a function of the ratios k and w reaches a value of 66% when these aa ratios have the respective values 0.5 and 0.26.
  • the waveguide, object of the invention further comprises a plurality of spacers 4 of dielectric material. These spacers keep the central conductive core in position.
  • the waveguide according to the invention comprises, inside the guide, a foam of dielectric material 5 allowing the central conductive core to be held in position. Any embodiment in which a support system for the central conducting core is used does not depart from the scope of the present invention.
  • Fc (TE 10 ) 5.588 GHz
  • Fc (TE 11 ) 11.300 GHz
  • the problem of finding the aa cutoff frequencies of the waveguide modes comes down to solving the two-dimensional Helmholtz equation in the cross section. of the guide. Two methods can preferably be used.
  • a first method allows a polynomial calculation of the field.
  • a second finite element method allows a longer but more expensive process to obtain more precise calculations.
  • a double-band wideband waveguide has thus been described which can be used in particular in any microwave circuit and in particular in broadband microwave connection circuits.

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

Description

La présente invention est relative aux guides d'ondes hyperfréquences à large bande, permettant la propagation dans des conditions identiques de fréquence de coupure et d'impédance de deux ondes électromagnétiques de polarisation, ou direction du champ électrique, orthogonales.The present invention relates to broadband microwave waveguides, allowing propagation under identical conditions of cutoff frequency and impedance of two electromagnetic waves of polarization, or direction of the electric field, orthogonal.

Dans les guides d'ondes à large bande, c'est-à-dire les guides d'ondes utilisés sur une plage de fréquences supérieure à la bande passante normale du guide d'onde, l'apparation de modes de propagation parasites, notamment lors d'une utilisation de ces guides d'ondes dans une bande passante sensiblement supérieure à 30% de la fréquence moyenne du guide d'onde, perturbe dangereusement le fonctionnement de ce dernier. En effet, dans un guide d'onde homogène, il existe une double infinité dénombrable de modes susceptibles de se propager: les modes dits modes TE et TM, respectivement transversaux électriques et transversaux magnétiques. Chaque mode de propagation possède une fréquence de coupure en dessous de laquelle la propagation s'effectue avec atténuation. Le domaine d'utilisation d'un guide d'onde ou bande passante est la plage de fréquences qui sépare la fréquence de coupure la plus basse, dite du mode fondamental, de la fréquence de coupure suivante, dite du premier mode d'ordre supérieur. Dans cet intervalle, le seul mode de propagation possible est celui du mode fondamental.In broadband waveguides, that is to say the waveguides used over a frequency range greater than the normal passband of the waveguide, the appearance of parasitic propagation modes, in particular when these waveguides are used in a bandwidth substantially greater than 30% of the average frequency of the waveguide, dangerously disturbs the operation of the latter. Indeed, in a homogeneous waveguide, there is a countable double infinity of modes liable to propagate: the modes known as TE and TM modes, electric transverse and magnetic transverse respectively. Each propagation mode has a cutoff frequency below which the propagation takes place with attenuation. The field of use of a waveguide or bandwidth is the frequency range which separates the lowest cutoff frequency, called the fundamental mode, from the next cutoff frequency, called the first higher order mode . In this interval, the only possible mode of propagation is that of the fundamental mode.

La bande passante est définie par le rapport:

Figure imgb0001
où λc 2 et λc 1 sont les longueurs d'onde de coupure du mode fondamental et du premier mode d'ordre supérieur.Bandwidth is defined by the ratio:
Figure imgb0001
 where λc 2 and λc 1 are the cutoff wavelengths of the fundamental mode and the first higher order mode.

La contrainte de la double polarisation impose à la section transversale du guide d'admettre l'axe longitudinal du guide d'onde comme axe de symétrie d'ordre 4n où n est un entier quelconque ≥ 1, une symétrie d'ordre 4n par rapport à cet axe longitudinal étant une symétrie telle qu'une rotation autour de ce même axe de la section du guide d'onde d'un angle de

Figure imgb0002
ne change pas les propriétés du guide d'onde, les polarisations de ce guide d'onde étant globalement inchangées.The constraint of the double polarization imposes on the cross section of the guide to admit the longitudinal axis of the wave guide as an axis of symmetry of order 4n where n is any integer ≥ 1, a symmetry of order 4n with respect to to this longitudinal axis being a symmetry such as a rotation around this same axis of the section of the waveguide by an angle of
Figure imgb0002
 does not change the properties of the waveguide, the polarizations of this waveguide being generally unchanged.

Cependant, un mode déterminé ne se propage que s'il existe les conditions nécessaires à son excitation, le mode TE20, mode dissymétrique, n'apparaissant pas dans un guide d'onde où sont maintenues des conditions de symétrie de propagation radioélectrique, même au-delà de la fréquence de coupure du mode TE20. Par contre, un coudage du guide, propre à créer une dissymétrie, provoque l'apparition du mode TEzo. Un guide n'est donc utilisable, en dehors de sa bande passante, que dans des conditions très particulières de symétrie mécanique et/ou radioélectrique.However, a determined mode propagates only if there are the conditions necessary for its excitation, the TE 20 mode, asymmetrical mode, not appearing in a waveguide where radio propagation symmetry conditions are maintained, even beyond the TE 20 cutoff frequency. On the other hand, a bending of the guide, capable of creating an asymmetry, causes the appearance of the TE zo mode. A guide can therefore only be used, outside of its bandwidth, under very specific conditions of mechanical and / or radio symmetry.

Différentes solutions ont été proposées, en vue de l'augmentation de la bande passante, sans provoquer l'apparition de modes parasites d'ordre supérieur. Une solution consiste à ajouter à la structure du guide d'onde un redan, connu sous le vocable anglosaxon de »ridge«, n'a pas permis, dans le cas des guides de section circulaire ou carrée, d'obtenir un accroissement de bande passante aussi important que dans le cas du guide de section rectangulaire. De tels résultats ont été publiés; notamment dans le cadre des études effectuées par M. H. Chen, G. N. Tsandou- las et F. G. Willwerth, intitulées »Modal Cha- racteristics of quadruple-ridged circular and square waveguides«, publiées dans la revue IEEE-Trans Microwave Theory Tech Vol MTT 22, pages 801 à 804, Août 1974.Different solutions have been proposed, with a view to increasing the bandwidth, without causing the appearance of parasitic modes of higher order. One solution consists in adding to the structure of the waveguide a step, known under the term Anglosaxon of "ridge", did not make it possible, in the case of the guides of circular or square section, to obtain an increase in band as important as in the case of the rectangular section guide. Such results have been published; notably in the framework of studies carried out by MH Chen, GN Tsandoulas and FG Willwerth, entitled “Modal Characteristics of quadruple-ridged circular and square waveguides“, published in the journal IEEE-Trans Microwave Theory Tech Vol MTT 22, pages 801 to 804, August 1974.

Une autre solution, consistant à introduire des redans carrés dans les angles dièdres formés par les côtés d'un guide d'onde de section carrée, a permis d'obtenir une bande passante de 38% ce type de guide d'onde pouvant être utilisé sur un octave de bande, avec seulement un mode parasite TE20 désigné comme modeTE201 obtenu lorsque la dégénérescence entre le mode TE20 et le mode TE02d'un guide carré est levée par l'adjonction de redans. Une telle solution a été publiée par H. J. Stalzer, M. D. Greenman et F. G. Willwerth dans une publication intitulée »Modes of crossed rectangular waveguide« dans la revue IEEE-Trans Ant Propag - AP, March 1976.Another solution, consisting in introducing square steps in the dihedral angles formed by the sides of a square section waveguide, made it possible to obtain a bandwidth of 38% this type of waveguide which can be used. on a band octave, with only one TE 20 parasitic mode designated as TE mode 201 obtained when the degeneration between TE 20 mode and TE 02 mode of a square guide is lifted by the addition of steps. One such solution was published by HJ Stalzer, MD Greenman and FG Willwerth in a publication entitled "Modes of crossed rectangular waveguide" in the journal IEEE-Trans Ant Propag - AP, March 1976.

Dans ces différentes solutions, l'adjonction de redans à des guides d'ondes de section carrée, octogonale, ou circulaire n'a jamais permis de dépasser une bande passante de 40%In these different solutions, the addition of steps to square, octagonal or circular section waveguides has never made it possible to exceed a bandwidth of 40%

Une autre solution consiste à adjoindre à des guides d'ondes de section rectangulaire un noyau central conducteur. Une telle solution a été décrite, notamment, dans l'article de L. Gruner, intitulé »Higher order modes in rectangularwave- guides« et pulié dans la revue IEEE-Trans microwave theory tech (Corresp.) Vol MTT 15, pages 483 à 485, August 1967.Another solution consists in adding to the waveguides of rectangular section a central conductive core. Such a solution has been described, in particular, in the article by L. Gruner, entitled "Higher order modes in rectangularwave-guides" and published in the review IEEE-Trans microwave theory tech (Corresp.) Vol MTT 15, pages 483 to 485, August 1967.

On connait aussi par la FR-A-2 116 441 un guide d'onde à large bande et double polarisation dans lequel la section efficace est cruciforme. Ce guide d'onde est constitué par un conducteur creux, de section rectangulaire ou carrée, sur la face interne duquel sont disposés quatre coins situés sur les bissectrices des axes principaux de propagation dans le but d'obtenir la transmission de l'onde injectée avec un amortissement particu- tièrement faible.Also known from FR-A-2 116 441 is a broadband, double polarization waveguide in which the cross section is cruciform. This waveguide consists of a hollow conductor, of rectangular or square section, on the internal face of which are arranged four corners situated on the bisectors of the main axes of propagation in order to obtain the transmission of the wave injected with particularly low depreciation.

La présente invention a pour but d'accroitre notablement la bande passante d'un guide d'onde en vue d'obtenir des bandes passantes supérieures à 60%The present invention aims to significantly increase the bandwidth of a waveguide in order to obtain bandwidths greater than 60%

L'objet de l'invention est un guide d'onde à large bande et à double polarisation constitué d'un conducteur creux de section polygonale ayant par rapport à son centre de symétrie, une symétrie d'ordre 4n, dans laquelle n est un entier, et deux axes principaux de propagation, mutuellement orthogonaux, la face interne de ce conducteur creux est munie de quatre redans dont les plans de symétrie longitudinaux sont situés selon les bissectrices des axes principaux de propagation et ce guide d'onde comporte un noyau central conducteur de forme polygonale, la section de ce noyau central et celle du conducteur creux étant homothétiques par rapport au centre de symétrie.The subject of the invention is a wideband, double polarization waveguide consisting of a hollow conductor of polygonal section having with respect to its center of symmetry, a symmetry of order 4n, in which n is an integer, and two main axes of propagation, mutually orthogonal, the internal face of this hollow conductor is provided four notches whose longitudinal planes of symmetry are located along the bisectors of the main axes of propagation and this waveguide comprises a central conductive core of polygonal shape, the section of this central core and that of the hollow conductor being homothetic with respect to the center of symmetry.

Le guide d'onde selon l'invention peut être utilisé dans tout système de connexion ou circuit hyperfréquence utilisé dans la transmission de signaux à large bande de fréquence. L'invention sera mieux comprise à l'aide de la description et des dessins ci-après où les cotes et proportions relatives des différents éléments n'ont pas été respectées, afin d'assurer une meilleure compréhension de l'ensemble et dans lesquels,

  • - la figure 1 représente un guide d'onde à large bande à double polarisation, selon l'invention;
  • - les figures 2a, 2b représentent respectivement la variation des fréquences de coupure, d'une part pour un guide d'onde à redans diagonaux seul, et d'autre part, pour un guide d'onde à noyau central conducteur seul;
  • - les figures 3a, 3b représentent la variation de la fréquence de coupure du guide d'onde, selon le mode de réalisation de l'invention, tel que représenté figure 1, en fonction des paramètres géométriques du mode de réalisation considéré;
  • - les figures 4a et 4b représentent une vue de face d'une coupe, selon un plan orthogonal à l'axe longitudinal du guide d'onde du mode de réalisation de la figure 1, selon deux variantes de réalisation particulières.
The waveguide according to the invention can be used in any connection system or microwave circuit used in the transmission of broadband frequency signals. The invention will be better understood using the description and the drawings below where the dimensions and relative proportions of the different elements have not been respected, in order to ensure a better understanding of the whole and in which,
  • - Figure 1 shows a broadband waveguide with double polarization, according to the invention;
  • - Figures 2a, 2b respectively show the variation of the cut-off frequencies, on the one hand for a waveguide with diagonal steps only, and on the other hand, for a waveguide with a conductive central core only;
  • - Figures 3a, 3b show the variation of the cutoff frequency of the waveguide, according to the embodiment of the invention, as shown in Figure 1, depending on the geometric parameters of the embodiment considered;
  • - Figures 4a and 4b show a front view of a section along a plane orthogonal to the longitudinal axis of the waveguide of the embodiment of Figure 1, according to two particular embodiments.

Selon la figure 1, le guide d'onde à large bande à double polarisation, objet de l'invention, comprend un conductur creux de section polygonale 1 présentant, par rapport à un centre de symétrie C, une symétrie d'ordre 4n où n est un entier quelconque. Le guide d'onde, selon l'invention, contient à l'intérieur du conducteur creux de section polygonale une pluralité de redans conducteurs 2, dont la section détermine, avec la section polygonale, une section de propagation du guide d'onde. Chacun des redans 2 est disposé sur la face interne des côtés du conducteur creux, selon une symétrie d'ordre 4 par rapport au centre de symétrie C. Le plan de symétrie longitudinal de chacun des redans est orienté, dans la section de propagation du guide d'onde, dans la direction des bissectrices des axes principaux du guide d'onde. Sur la figure 1, les axes principaux du guide d'onde sont représentés par les axes X'X, et Y'Y, leur orientation correspond respectivement à la direction des champs électriques des modes de propagation TElQ et TEoi, pour le guide d'onde considéré. Sur la figure 1, le plan de symétrie longitudinal de chaque redan n'a pas été représenté afin de ne pas surcharger la figure. Le guide d'onde, selon l'invention, comporte, d'autre part, à l'intérieur du conducteur creux de section polygonale, un noyau centrai conducteur 3, dont la section présente par rapport au centre de symétrie C une même symétrie d'ordre 4n, les sections du noyau central conducteur et du conducteur creux de section polygonale étant homothétiques par rapport à ce centre de symétrie C.According to FIG. 1, the wide-band double polarization waveguide, object of the invention, comprises a hollow conductor of polygonal section 1 having, with respect to a center of symmetry C, a symmetry of order 4n where n is any integer. The waveguide according to the invention contains inside the hollow conductor of polygonal section a plurality of conductive steps 2, the section of which determines, with the polygonal section, a propagation section of the waveguide. Each of the steps 2 is arranged on the internal face of the sides of the hollow conductor, according to a symmetry of order 4 with respect to the center of symmetry C. The longitudinal plane of symmetry of each of the steps is oriented, in the propagation section of the guide in the direction of the bisectors of the main axes of the waveguide. In FIG. 1, the main axes of the waveguide are represented by the axes X'X, and Y'Y, their orientation corresponds respectively to the direction of the electric fields of the propagation modes TE lQ and TE oi , for the guide wave considered. In FIG. 1, the longitudinal plane of symmetry of each step has not been shown so as not to overload the figure. The waveguide according to the invention comprises, on the other hand, inside the hollow conductor of polygonal section, a central conductive core 3, the section of which has with respect to the center of symmetry C the same symmetry d order 4n, the sections of the central conductive core and of the hollow conductor of polygonal section being homothetic with respect to this center of symmetry C.

Selon la figure 1, le conducteur creux de section polygonale a une section carrée de côté 2a. Cette section présente, par rapport au centre de symétrie C, une symétrie d'ordre 4. Le conducteur creux comporte, à l'intérieur de chaque angle dièdre formé par deux côtés consécutifs de la section carrée, un redan conducteur 2 de section également carrée du côté W. Les quatre redans disposés dans la section du conducteur creux, à l'extrémité des diagonales de cette section, déterminent, avec la section carrée du conducteur creux, une section de propagation du guide d'onde présentant, par rapport à ce même centre de symétrie C, une symétrie d'ordre 4. Selon l'invention, le conducteur creux de section polygonale comporte, d'autre part, un noyau central conducteur 3 dont la section carrée de côté 2k présente, par rapport à ce même centre de symétrie C, une même symétrie d'ordre 4. Ainsi, les diagonales de la section carrée du conducteur creux 1 et les diagonales de la section du noyau central conducteur sont confondues.According to Figure 1, the hollow conductor of polygonal section has a square side section 2a. This section presents, with respect to the center of symmetry C, a symmetry of order 4. The hollow conductor comprises, inside each dihedral angle formed by two consecutive sides of the square section, a conductive step 2 of also square section on the W side. The four steps arranged in the section of the hollow conductor, at the end of the diagonals of this section, determine, with the square section of the hollow conductor, a propagation section of the waveguide having, with respect to this same center of symmetry C, a symmetry of order 4. According to the invention, the hollow conductor of polygonal section comprises, on the other hand, a central conductive core 3 whose square section of side 2k has, with respect to this same center of symmetry C, the same order 4 symmetry. Thus, the diagonals of the square section of the hollow conductor 1 and the diagonals of the section of the central conductive core are combined.

Le fonctionnement du guide d'onde, objet de l'invention, est le suivant compte tenu des figures 2a et 2b dans lesquelles la figure 2a comporte un système d'axes dont les ordonnées sont graduées en fréquence de coupure normalisée ou rapport de la dimension du guide, selon la figure 1, à la longueur d'onde de coupure de ce même guide, la fréquence de coupure normalisée étant notée

Figure imgb0003
et dont les abscisses sont graduées en rapport de la dimension du côté du redan W à la même dimension 2a du guide d'onde. La figure 2a représente les variations des fréquences de coupure des modes principaux de propagation tels que les modes TE11, TM11, TE201 et TE10. De la même manière, la figure 2b représente, sur un système d'axes, respectivement en ordonnées, les fréquences de coupure normalisées du guide d'onde, l'axe d'ordonnées étant gradué en valeur du rapport
Figure imgb0004
où 2a représente la dimension du côté de la section carrée du guide d'onde, selon la figure 1, et λ c la longueur d'onde de coupure correspondante, en fonction du rapport de la dimension du noyau central conducteur de section carrée de côté 2k rapportée à cette même dimension du guide d'onde de section carrée et de côté 2a. La figure 2b représente les différentes fréquences de coupure normalisées pour les principaux modes tels que TM11, TE201, TE11, et TE10. Les figures 2a et 2b montrent respectivement que, dans les cas du guide carré comportant les seuls redans à l'intérieur de chaque angle dièdre formé par deux côtés consécutifs de la section carrée, le mode TM11 limite la bande passante tant que le rapport
Figure imgb0005
reste inférieur à 0,22, le mode TE201 devenant sensiblement le premier mode parasite pour des valeurs supérieures de ce rapport. D'une autre manière, la figure 2b montre que, dans le cas du guide de section carrée comportant un noyau central de section également carrée, le seul mode d'ordre supérieur limitant la bande passante est le mode TE11 dont la fréquence de coupure dépend peu du rapport
Figure imgb0006
Selon l'ivention, l'utilisation simultanée des caractéristiques de propagation du guide seul comportant les redans, telles que représentées figure 2a, et des caracteristiques de propagation du guide de section carrée comportant un noyau central conducteur de section également carrée telles que représentées figure 2b, permet en par- ticutier d'obtenir, ainsi que représenté figure 3a et figure 3b, une réjection vers les fréquences supérieures de la fréquence de coupure du mode TM1 et une variation parabolique en fonction du rapport W de la fréquence de coupure pour le mode a TE11. La bande passante du guide ainsi réalisé est fonction des rapportsWetK,paramètres géomé- a a triques du guide selon l'invention. Pour une valeur K déterminée, il existe un rapport W optimat pour a a lequel la bande passante est maximum. La valeur de la bande passante BW optenue par la mise en oeuvre d'un guide d'onde selon l'invention tel que représenté figure 1, est donnée dans le tableau suivant, en fonction des valeurs des rapports K et W . a a
Figure imgb0007
Figure imgb0008
 The operation of the waveguide, object of the invention, is as follows taking into account FIGS. 2a and 2b in which FIG. 2a comprises a system of axes whose ordinates are graduated in standard cut-off frequency or ratio of dimension of the guide, according to FIG. 1, at the cut-off wavelength of this same guide, the normalized cut-off frequency being noted
Figure imgb0003
 and whose abscissae are graduated in relation to the dimension on the side of the step W to the same dimension 2a of the waveguide. FIG. 2a represents the variations in the cutoff frequencies of the main propagation modes such as the TE 11 , TM 11, TE 201 and TE 10 modes. In the same way, FIG. 2b represents, on a system of axes, respectively on the ordinate, the normalized cut-off frequencies of the waveguide, the ordinate axis being graduated in value of the ratio
Figure imgb0004
 where 2a represents the dimension of the side of the square section of the waveguide, according to FIG. 1, and λ c the corresponding cut-off wavelength, as a function of the ratio of the dimension of the central conducting core of square section of side 2k related to this same dimension of the square section waveguide and side 2a. FIG. 2b represents the different standardized cut-off frequencies for the main modes such as TM 11 , TE 201 , TE 11 , and TE 10 . Figures 2a and 2b respectively show that, in the case of the square guide comprising the only steps within each dihedral angle formed by two consecutive sides of the square section, the TM 11 mode limits the bandwidth as long as the ratio
Figure imgb0005
 remains less than 0.22, the TE 201 mode becoming substantially the first parasitic mode for higher values of this ratio. In another way, FIG. 2b shows that, in the case of the square section guide comprising a central core of also square section, the only higher order mode limiting the bandwidth is the TE 11 mode whose cut-off frequency depends little on the report
Figure imgb0006
 According to the ivention, the simultaneous use of the propagation characteristics of the guide alone comprising the steps, as shown in FIG. 2a, and of the propagation characteristics of the guide of square section comprising a central conductive core of section also square as shown in FIG. 2b , allows in particular to obtain, as shown in FIG. 3a and FIG. 3b, a rejection towards the higher frequencies of the cutoff frequency of the TM 1 mode and a parabolic variation as a function of the ratio W of the cutoff frequency for the TE mode 11 . The bandwidth of the guide thus produced is a function of the ratios W and K , geometrical parameters of the guide according to the invention. For a determined K value, there is an optimal W ratio for which the bandwidth is maximum. The value of the bandwidth BW obtained by the implementation of a waveguide according to the invention as shown in FIG. 1, is given in the following table, as a function of the values of the ratios K and W. aa
Figure imgb0007
Figure imgb0008

Les figures 3a et 3b représentent pour différentes valeurs du rapport k la variation de la fré- a quence de coupure normalisée

Figure imgb0009
, rapport de la demi-dimension du guide d'onde de section carrée à la longeur d'onde de coupure du guide, en fonction du rapport W, dimension du côté de la a section du redan carré rapportée à cette même demi-dimension a de la section du guide d'onde. Le guide d'onde selon l'invention permet d'obtenir une bande passante plus importante que celle des guides jusqu'alors utilisés pour résoudre des problèmes analogues. La bande passante du guide suivant l'invention, fonction des rapports k et w, atteint une valeur de 66% lorsque ces a a rapports ont pour valeur respective 0,5 et 0,26.Figures 3a and 3b show for different values of the ratio k the variation of the normalized cut-off frequency
Figure imgb0009
 , ratio of the half-dimension of the square section waveguide to the cut-off wavelength of the guide, as a function of the ratio W , dimension of the side of the section of the square step related to this same half-dimension a of the waveguide section. The waveguide according to the invention makes it possible to obtain a higher bandwidth than that of the guides hitherto used to solve similar problems. The bandwidth of the guide according to the invention, a function of the ratios k and w , reaches a value of 66% when these aa ratios have the respective values 0.5 and 0.26.

Selon la figure 4a, le guide d'onde, objet de l'invention, comporte en outre une pluralité d'entretoises 4 de matériau diélectrique. Ces entretoises permettent de maintenir en position le noyau central conducteur. Selon une variante de réalisation représentée figure 4b, le guide d'onde selon l'invention comporte à l'intérieur du guide une mousse de matériau diélectrique 5 permettant de maintenir en position le noyau central conducteur. Tout mode de réalisation dans lequel un système de maintien du noyau central conducteur est utilisé ne sort pas du cadre de la présente invention. A titre d'exemple, les fréquences de coupure principales d'un guide, pour lesquelles les dimensions resoectives étaient

Figure imgb0010
ont été pour le modeTE10: Fc (TE10) = 5,588 GHz, pour le mode TE11 : Fc (TE11 ) = 11,300 GHz, pour le modeTE201 : Fc (TE201)=10,808 GHz. Pour des valeurs de paramètres déterminés, valeur des rapports W et K , le`problème de la recherche des a a fréquences de coupure des modes du guide d'onde se résume à la résolution de l'équation de Helmholtz à deux dimensions dans la section transversale du guide. Deux méthodes peuvent être de préférence utilisées.According to Figure 4a, the waveguide, object of the invention, further comprises a plurality of spacers 4 of dielectric material. These spacers keep the central conductive core in position. According to an alternative embodiment shown in FIG. 4b, the waveguide according to the invention comprises, inside the guide, a foam of dielectric material 5 allowing the central conductive core to be held in position. Any embodiment in which a support system for the central conducting core is used does not depart from the scope of the present invention. For example, the main cutoff frequencies of a guide, for which the resoective dimensions were
Figure imgb0010
 were for the TE 10 mode: Fc (TE 10 ) = 5.588 GHz, for the TE 11 mode: Fc (TE 11 ) = 11.300 GHz, for the TE 201 mode: Fc (TE 201 ) = 10.808 GHz. For determined parameter values, value of the W and K ratios, the problem of finding the aa cutoff frequencies of the waveguide modes comes down to solving the two-dimensional Helmholtz equation in the cross section. of the guide. Two methods can preferably be used.

Une première méthode, la méthode de Ray- leigh-Ritz, permet un calcul polynômial du champ. Une deuxième méthode par éléments finis, permet par un processus plus long mais plus coûteux d'obtenir des calculs plus précis. On a ainsi décrit un guide d'onde à large bande à double polarisation utilisable en particulier dans tout circuit hyperfréquence et notamment dans les circuits de connexion hyperfréquences à large bande.A first method, the Rayleigh-Ritz method, allows a polynomial calculation of the field. A second finite element method allows a longer but more expensive process to obtain more precise calculations. A double-band wideband waveguide has thus been described which can be used in particular in any microwave circuit and in particular in broadband microwave connection circuits.

Claims (6)

1. A wide band wave guide with double polarization comprising a polygonal wave guide (1) having, with respect to its center of symmetry C, a symmetry of order 4n, in which n is an integer, and comprising two main axes of propagation X and Y which are mutually perpendicular, characterized in that the inner face of said wave guide (1) is provided with four ridges (2), the longitudinal symmetry planes of which are located along the bisectrix lines of the main propagation axes, and that it comprises a central conductive core (3) with a polygonal cross-section, the cross-section of this central core (3) and the cross-section of the wave guide being homothetical with respect to the center of symmetry C.
2. A wave guide according to claim 1, in which n is equal to the unity, characterized in that the four internal ridges (2) have a square cross-section with side lenghts W and are located in the diedral angle of the wave guide (1) and that the central conductive core (3) presents also a square cross-section with side lenghts 2k.
3. A wave guide according to claim 2, characterized in that the ratio between the side lenght W of the internal ridges (2) and half of the side lenght 2a of the wave guide (1) is chosen at a value between 0,22 and 0,36.
4. A wave guide according to claim 2, characterized in that the ratio between the side lenght 2k of the central core (3) and the side lenght 2a of the wave guide (1) is chosen at a value between 0,2 and 0,6.
5. A wave guide according to anyone of the preceding claims, characterized in that it comprises a plurality of spacers (4) for mechanically connecting the conductive central core (3) to the wave guide (1).
6. A wave guide according to one of the preceding claims, characterized in that it comprises a dielectric foam material (5) which is located between the conductive central core (3) and the wave guide (1).
EP80400448A 1979-04-13 1980-04-03 Wide-band waveguide with double polarisation Expired EP0018261B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7909493A FR2454188A1 (en) 1979-04-13 1979-04-13 DOUBLE POLARIZATION BROADBAND WAVEGUIDE AND MICROWAVE CIRCUIT HAVING SUCH A WAVEGUIDE
FR7909493 1979-04-13

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EP0018261A1 EP0018261A1 (en) 1980-10-29
EP0018261B1 true EP0018261B1 (en) 1984-03-14

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US4523160A (en) * 1983-05-02 1985-06-11 George Ploussios Waveguide polarizer having conductive and dielectric loading slabs to alter polarization of waves
US4904966A (en) * 1987-09-24 1990-02-27 The United States Of America As Represented By The Secretary Of The Navy Suspended substrate elliptic rat-race coupler
US7061445B2 (en) * 2003-08-26 2006-06-13 Andrew Corporation Multiband/multichannel wireless feeder approach
WO2006019776A2 (en) * 2004-07-14 2006-02-23 William Marsh Rice University A method for coupling terahertz pulses into a coaxial waveguide
US7531803B2 (en) * 2006-07-14 2009-05-12 William Marsh Rice University Method and system for transmitting terahertz pulses

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DE1013338B (en) * 1952-12-27 1957-08-08 Pintsch Electro Gmbh Inner conductor, especially for VHF lines, with enlarged electrical length
US3002163A (en) * 1960-01-08 1961-09-26 Polytechnic Inst Brooklyn Mode coupler for circular waveguides
US3150333A (en) * 1960-02-01 1964-09-22 Airtron Division Of Litton Pre Coupling orthogonal polarizations in a common square waveguide with modes in individual waveguides
US3569870A (en) * 1968-08-21 1971-03-09 Rca Corp Feed system
DE2055443C3 (en) * 1970-11-11 1982-02-25 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Polarization converter for microwaves
FR2116441B1 (en) * 1970-12-03 1974-08-19 Licentia Gmbh
US4035598A (en) * 1974-10-22 1977-07-12 Johannes Menschner Maschinenfabrik Gmbh & Co. Kg. Apparatus for thermally treating polymeric workpieces with microwave energy
FR2294554A1 (en) * 1974-12-10 1976-07-09 Thomson Csf Rectangular coaxial line section for RF oscillator - U-shaped closed by cover plate and enclosing inner conductor with diode

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FR2454188B1 (en) 1983-03-11
FR2454188A1 (en) 1980-11-07
EP0018261A1 (en) 1980-10-29
US4303900A (en) 1981-12-01
DE3066913D1 (en) 1984-04-19

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