EP0189712B1 - Ridged waveguide with a fluid-tight window - Google Patents

Ridged waveguide with a fluid-tight window Download PDF

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Publication number
EP0189712B1
EP0189712B1 EP85402616A EP85402616A EP0189712B1 EP 0189712 B1 EP0189712 B1 EP 0189712B1 EP 85402616 A EP85402616 A EP 85402616A EP 85402616 A EP85402616 A EP 85402616A EP 0189712 B1 EP0189712 B1 EP 0189712B1
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Prior art keywords
guide
window
sides
disk
whose
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German (de)
French (fr)
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EP0189712A1 (en
Inventor
Jacques Tikes
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Thales SA
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Thomson CSF SA
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01PWAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00Auxiliary devices
    • H01P1/08Dielectric windows

Definitions

  • the present invention relates to rectangular waveguides and more particularly to waveguides with moldings (ridge wave-guides in Anglo-Saxon literature) provided with a sealed window, that is to say with a bulkhead transparent to electromagnetic energy and gas and moisture tight.
  • the object of the present invention is to enable a molded waveguide to be provided with a sealed window while keeping an operating frequency band greater than the octave.
  • a rectangular waveguide with moldings provided with a sealed window
  • the window is a thin window, that is to say a window whose dielectric has a thickness which represents a electrical length at least five times lower than the guided wavelength corresponding to the highest working frequency in the guide
  • the window is composed of a metal frame and a dielectric plate, the frame being pierced with an opening and the plate closing this opening, in that, in projection on a transverse plane of the guide, the opening has an oblong shape whose largest dimension is parallel to the long sides of the guide and whose dimensions outside all, parallel respectively to the large and to the short sides of the guide, are respectively smaller than the dimensions of the long sides (A) and the short sides (B) of the guide, and in that it comprises an adaptation transformer arranged in a share area and on the other side of the window, this transformer being obtained by giving the guide moldings a height, relative to the wall on which they are located, greater in the area than outside the area.
  • FIGS. 1 and 2 show a rectangular waveguide 1 whose long sides and short sides have a width A and a width B respectively;
  • FIG. 1 is a view in longitudinal section of this guide through that of the planes of symmetry of the guide which is perpendicular to the long sides, while
  • FIG. 2 is a transverse view through a plane whose trace XX is indicated in FIG. 1.
  • the guide of FIGS. 1 and 2 has two identical longitudinal moldings, respectively placed in the middle of the two long sides and separated by a distance D.
  • a tight, thin window composed of 'a metal frame, 5, made of ferronickel, surrounding a ceramic dielectric plate 4, was placed inside the guide perpendicular to the four sides of the latter; this plate 4 has the shape of a rectangle with rounded angles, of dimensions a by b and whose long and short sides are respectively parallel to the long and short sides of the guide 1.
  • FIG. 3 is a representation of this susceptance curve in a Smith chart where the direction of the source to charge displacement has been indicated by an arrow Ch.
  • the susceptance varies regularly as a function of frequency; it passes successively through pure inductive values, zero for FO and pure capacitive, in the increasing direction of the frequencies of the band F1 - F2.
  • the adaptation is therefore correct only for the frequency F0; to carry out the adaptation in the entire band F1 - F2 it is proposed to add a half-wave transformer and thus to carry out a broadband adaptation.
  • Figures 4 to 11 show how such a matching transformer can be used and what this results for the susceptance curve (Figure 7).
  • Figures 4, 5 and 6 show how the guide according to Figures 1 and 2 can be modified to incorporate a half-wave type impedance matching transformer.
  • FIG. 6 has been given in addition Figures 4 and 5 to allow a better understanding of how the guide was made; it is a cross-sectional view through the plane of symmetry of the guide which is parallel to the long sides of the guide.
  • window 4 - 5 presents the curve (1) of susceptance which corresponds to the curve of figure 3 after a rotation of 180 ° around from point 3 of coordinates (1, 0) which is due to the transformer.
  • the curve (1) of FIG. 7 undergoes a resistive translation, function of the spacing d, and becomes the curve (2).
  • cp designates the angle whose apex is point J and whose sides pass through the ends of the curve (2) relating to frequencies F1 and F2
  • the value of the spacing d of the half-wave transformer is adjusted so that this angle (p is equal to the difference in rotation (towards the load: arrow Ch) of the points representative of the frequencies F1 and F2 along the transformer, that is to say that:
  • the guide section of length L then behaves like a grouping space; in the observation plane P2, after a rotation towards the load on a circle with ROS (standing wave ratio) constant of the Smith diagram, all the points relating to the different frequencies of the band, are grouped in 1, then in J after this same plan; thus the adaptation is obtained for all the frequencies of the band F1 - F2.
  • ROS standing wave ratio
  • window 4 - 5 must satisfy not only the problem of adaptation but also that of the rejection of parasitic resonances outside the band of operating frequencies of the molding guide. To find a solution allowing the rejection of these parasitic frequencies, experience shows that it is not possible to take, as the value b of the small dimension of the plate 4, the value for which the dielectric plate does not cause no variation in capacity along the transmission line that constitutes the guide 1.
  • the large dimension, a, of the metal frame 5 should be equal to the internal width, A, of the guide with moldings, so as not to make a selfic contribution which would not be counterbalanced by a capacitive contribution; however, the volume of the plate 4 would then be large enough to introduce parasitic resonances (ghost modes in Anglo-Saxon literature) into the bandwidth of the molding guide; it is therefore necessary to give the small size of the plate a value b which is sufficiently reduced compared to the value which would not cause any variation in capacity along the transmission line. This reduction which reveals a capacitive component must be canceled by a corresponding inductive contribution which is a function of the value A - a (FIG. 5). It should be noted that the reduction of b which has just been mentioned must not be excessive because otherwise the inductive contribution necessary for the cancellation of the capacitive contribution becomes significant, which increases the selectivity of the window guide and is therefore incompatible with the broadband adaptation which is sought.
  • FIG. 8 is a longitudinal section of a rectangular waveguide, 1, with moldings, 2, 3, by a perpendicular plane. at the long sides of the guide.
  • Figure 9 is a cross-sectional view through a plane whose trace, YY, is indicated in Figure 8.
  • a window consisting of a metal frame 5 and a dielectric plate 4, is arranged in a transverse plane of the guide, substantially in the middle of a half-wave transformer. Molding sections, the spacing of which is smaller than the spacing of the moldings in the rest of the waveguide 1, appear in FIG. 8; these sections constitute the half-wave transformer.
  • This window guide differs from that according to FIGS.
  • the two examples which have just been described relate to windows arranged in a transverse plane of the molding guide and provided with a dielectric plate, 4, of oblong shape, the largest dimension of which was parallel to the long sides of the guide in order to '' equalize the inductive contributions and the capacitive contributions due to the presence of this dielectric plate.
  • the dielectric plate would no longer be oblong in shape but would be circular there would no longer be the possibility of equalizing the capacitive and inductive contributions, the latter being always preponderant; in this case it is not possible to obtain a standing wave ratio of less than 2, even in a band reduced to two thirds of the pass band of the guide.
  • FIGS. 10 and 11 show a guide according to the invention, comprising an inclined window 4 - 5, with a circular dielectric plate 4 and metallic frame 5.
  • FIG. 10 which is a view in longitudinal section through the plane of symmetry of the guide which is perpendicular to the long sides of the guide, shows the guide 1 with its moldings 2, 3 which, over a length L, are brought together to form an adaptation transformer.
  • Figure 11 is a cross-sectional view of the guide, through a plane whose trace ZZ is shown in Figure 10; this figure shows that, in the section plane, the projection ellipse of the plate 4 has its major axis, not shown, parallel to the long sides of the guide.
  • the ceramic plate 4 is fixed to the ferronickel frame 5 by brazing on a plate, that is to say that the solder disposed between the plate 4 and the frame 5, is in contact with the plate only on one of the faces thereof and forms a cord closed on itself whose outer edge matches the edge of the face considered.
  • Any other method of attachment is possible insofar as it ensures the solidity and sealing of the window: brazing on the field of the plate or combination of brazing on the field with brazing on a plate, or bonding ...
  • the present invention is not limited to the examples described, this is how, for the opening, any oblong shape or oblong transverse projection can be suitable insofar as it makes it possible to balance the capacitive and inductive inputs.
  • the window 4 - 5 is located in the area of the impedance transformer (sections of moldings 20, 21, 30, 31 in FIG. 4)
  • the present invention is very particularly applicable to the production of microwave power windows, capable of working in a frequency band greater than one octave without parasitic frequencies in the operating band.

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  • Waveguide Connection Structure (AREA)
  • Microwave Tubes (AREA)
  • Waveguides (AREA)

Description

La présente invention se rapporte aux guides d'ondes rectangulaires et plus particulièrement aux guides d'ondes à moulures (ridge wave- guides dans la littérature anglo-saxonne) munis d'une fenêtre étanche, c'est-à-dire d'une cloison transparente à l'énergie électromagnétique et étanche aux gaz et à l'humidité.The present invention relates to rectangular waveguides and more particularly to waveguides with moldings (ridge wave-guides in Anglo-Saxon literature) provided with a sealed window, that is to say with a bulkhead transparent to electromagnetic energy and gas and moisture tight.

Lorsqu'une large bande de fréquences de fonctionnement est désirée pour un guide rectangulaire muni d'une fenêtre étanche il est tentant d'utiliser un guide à moulures c'est-à-dire, comme le définit le "vocabulaire électronique international", un guide avec une ou deux moulures rentrantes s'étendant sur toute la longueur et en contact avec les parois. Un tel guide muni d'une fenêtre est connu par le brevet US 3 860 891 déposé le 11 juin 1973; ce brevet décrit une fenêtre diélecrique épaisse avec, de part et d'autre une petite zone de transition ou les moulures sont supprimées et où la section transversale du guide a une hauteur égale à la hauteur maximale de la section du guide contenant le diélectrique de la fenêtre. Ce guide à fenêtre a malheureusement une bande de fonctionnement limitée à l'octave et est susceptible de produire des résonances parasites dues à l'épaisseur du diélectrique.When a wide operating frequency band is desired for a rectangular guide provided with a sealed window, it is tempting to use a molding guide, that is to say, as defined by "international electronic vocabulary", a guide with one or two re-entrant moldings extending over the entire length and in contact with the walls. Such a guide provided with a window is known from US Pat. No. 3,860,891 filed on June 11, 1973; this patent describes a thick dielectric window with, on either side a small transition zone where the moldings are removed and where the cross section of the guide has a height equal to the maximum height of the section of the guide containing the dielectric of the window. This window guide unfortunately has an operating band limited to the octave and is capable of producing parasitic resonances due to the thickness of the dielectric.

Il est également connu par le brevet US 4 352 077 un guide à moulures muni d'une fenêtre disposée en biais d'un petit côté à l'autre du guide, et par la demande de brevet européen 0 031 275 un guide lisse muni d'une fenêtre à laquelle sont associés un ou deux volets selfiques et un transformateur d'impédance demi-onde fait de plaques occupant toute la largeur d'au moins un grand côté du guide d'onde; or là encore pour des raisons de largeur de bande de fonctionnement ces guides à fenêtre se sont révélés de qualité insuffisante dans certains cas d'utilisation et, de plus, en ce qui concerne le brevet US 4 352 077, des fréquences parasites peuvent apparaître, dues à des résonances internes de la fenêtre.It is also known from US Pat. No. 4,352,077 a guide with moldings provided with a window arranged obliquely from one side to the other of the guide, and by European patent application 0 031 275 a smooth guide provided with a window with which one or two inductive shutters are associated and a half-wave impedance transformer made of plates occupying the entire width of at least one long side of the waveguide; here again, for reasons of operating bandwidth, these window guides have proved to be of insufficient quality in certain use cases and, moreover, with regard to US Pat. No. 4,352,077, spurious frequencies may appear, due to internal resonances of the window.

La présente invention a pour but de permettre de munir un guide d'ondes à moulures d'une fenêtre étanche tout en gardant une bande de fréquences de fonctionnement supérieure à l'octave.The object of the present invention is to enable a molded waveguide to be provided with a sealed window while keeping an operating frequency band greater than the octave.

Ceci est principalement obtenu grâce à la combinaison d'un cadre métallique, d'une lame de diélectrique mince placée dans le cadre et d'un transformateur d'impédance.This is mainly achieved through the combination of a metal frame, a thin dielectric strip placed in the frame and an impedance transformer.

Selon l'invention un guide d'ondes rectangulaire à moulures, muni d'une fenêtre étanche, est caractérisé en ce que la fenêtre est une fenêtre mince, c'est-à-dire une fenêtre dont le diélectrique a une épaisseur qui représente une longueur électrique au moins cinq fois plus faible que la longueur d'onde guidée correspondant à la fréquence de travail la plus élevée dans le guide, en ce que la fenêtre est composée d'un cadre métallique et d'une plaque de diélectrique, le cadre étant percé d'une ouverture et la plaque obturant cette ouverture, en ce que, en projection sur un plan transversal du guide, l'ouverture a une forme oblongue dont la plus grande dimension est parallèle aux grands côtés du guide et dont les dimensions hors tout, parallèles respectivement aux grands et aux petits côtés du guide, sont respectivement plus petites que les dimensions des grands côtés (A) et des petits côtés (B) du guide, et en ce qu'il comporte un transformateur d'adaptation disposé dans une zone de part et d'autre de la fenêtre, ce transformateur étant obtenu en donnant aux moulures du guide une hauteur, par rapport à la paroi sur laquelle elles se trouvent, plus grande dans la zone que hors de la zone.According to the invention a rectangular waveguide with moldings, provided with a sealed window, is characterized in that the window is a thin window, that is to say a window whose dielectric has a thickness which represents a electrical length at least five times lower than the guided wavelength corresponding to the highest working frequency in the guide, in that the window is composed of a metal frame and a dielectric plate, the frame being pierced with an opening and the plate closing this opening, in that, in projection on a transverse plane of the guide, the opening has an oblong shape whose largest dimension is parallel to the long sides of the guide and whose dimensions outside all, parallel respectively to the large and to the short sides of the guide, are respectively smaller than the dimensions of the long sides (A) and the short sides (B) of the guide, and in that it comprises an adaptation transformer arranged in a share area and on the other side of the window, this transformer being obtained by giving the guide moldings a height, relative to the wall on which they are located, greater in the area than outside the area.

La présente invention sera mieux comprise et d'autres caractéristiques apparaîtront à l'aide de la description ci-après et des figures s'y rapportant qui représentent:

  • - les figures 1 et 2, deux vues en coupe d'un guide à moulures muni d'une fenêtre étanche,
  • - la figure 3, un abaque de Smith relatif au guide selon les figures 1 et 2,
  • - les figures 4 à 6, trois vues en coupe d'un guide selon l'invention,
  • - la figure 7, un abaque de Smith relatif au guide selon les figures 4 à 6,
  • - les figures 8 à 11, quatre vues en coupe relatives à deux autres guides selon l'invention.
The present invention will be better understood and other characteristics will appear with the aid of the description below and of the figures relating thereto which represent:
  • FIGS. 1 and 2, two sectional views of a molding guide provided with a sealed window,
  • FIG. 3, a Smith chart relating to the guide according to FIGS. 1 and 2,
  • FIGS. 4 to 6, three sectional views of a guide according to the invention,
  • FIG. 7, a Smith chart relating to the guide according to FIGS. 4 to 6,
  • - Figures 8 to 11, four sectional views relating to two other guides according to the invention.

Sur les différentes figures les éléments correspondants sont désignés par les mêmes symboles.In the various figures, the corresponding elements are designated by the same symbols.

Dans ce qui suit et dans les revendications, il sera question de fenêtres minces; il faudra entendre par là des fenêtres dont le diélectrique a une épaisseur qui représente une longueur électrique au moins cinq fois plus faible que la longueur d'onde guidée correspondant à la fréquence de travail la plus élevée dans le guide.In what follows and in the claims, it will be a question of thin windows; this means windows whose dielectric has a thickness which represents an electrical length at least five times lower than the guided wavelength corresponding to the highest working frequency in the guide.

Les figures 1 et 2 représentent un guide d'ondes rectangulaire 1 dont les grands côtés et les petits côtés ont respectivement une largeur A et une largeur B; la figure 1 est une vue en coupe longitudinale de ce guide par celui des plans de symétrie du guide qui est perpendiculaire aux grands côtés, tandis que la figure 2 est une vue transversale par un plan dont la trace XX est indiquée sur la figure 1. Le guide des figures 1 et 2 comporte deux moulures longitudinales identiques, disposées respectivement au milieu des deux grands côtés et séparées par une distance D. Pour les besoins de l'étude qui a abouti au guide revendiqué, une fenêtre étanche, mince, composée d'un cadre métallique, 5, en ferronickel, encadrant une plaque de diélectrique 4 en céramique, a été disposée à l'intérieur du guide perpendiculairement aux quatre côtés de ce dernier; cette plaque 4 a la forme d'un rectangle à angles arrondis, de dimensions a par b et dont les grands et les petits côtés sont respectivement parallèles aux grands et aux petits côtés du guide 1.Figures 1 and 2 show a rectangular waveguide 1 whose long sides and short sides have a width A and a width B respectively; FIG. 1 is a view in longitudinal section of this guide through that of the planes of symmetry of the guide which is perpendicular to the long sides, while FIG. 2 is a transverse view through a plane whose trace XX is indicated in FIG. 1. The guide of FIGS. 1 and 2 has two identical longitudinal moldings, respectively placed in the middle of the two long sides and separated by a distance D. For the purposes of the study which led to the claimed guide, a tight, thin window, composed of 'a metal frame, 5, made of ferronickel, surrounding a ceramic dielectric plate 4, was placed inside the guide perpendicular to the four sides of the latter; this plate 4 has the shape of a rectangle with rounded angles, of dimensions a by b and whose long and short sides are respectively parallel to the long and short sides of the guide 1.

Des mesures ont été effectuées pour des bandes de fréquences délimitées par les fréquences F1 et F2 et de fréquence centrale FO, avec F2 supérieur à Fo supérieur à F1 et λ 0, λ 1, λ 2 les longueurs d'ondes guidées correspondant aux fréquences F0, F1, F2. L'expérience a montré que lorsque la composante selfique, déterminée par A - a, et la composante capacitive, déterminée par B - b, de l'impédance dans le plan P du cadre, sont égales, à la fréquence F0, la fenêtre 4 - 5 présente, dans le plan P, une susceptance symétrique par rapport à l'axe des réels (axe des résistances pures) et passant par le milieu (1, 0) de cet axe sur l'abaque de Smith. La figure 3 est une représentation de cette courbe de susceptance dans un abaque de Smith où le sens du déplacement source vers charge a été indiqué par une flèche Ch. La susceptance varie régulièrement en fonction de la fréquence; elle passe successivement par des valeurs selfique pures, nulles pour FO et capacitives pures, dans le sens croissant des fréquences de la bande F1 - F2. L'adaptation n'est donc correcte que pour la fréquence F0; pour réaliser l'adaptation dans toute la bande F1 - F2 il est proposé d'ajouter un transformateur demi-onde et de réaliser ainsi une adaptation à large bande. Les figures 4 à 11 montrent comment un tel transformateur d'adaptation peut être utilisé et ce qu'il en résulte pour la courbe de la susceptance (figure 7).Measurements were carried out for frequency bands delimited by the frequencies F1 and F2 and of central frequency FO, with F2 greater than Fo greater than F1 and λ 0, λ 1, λ 2 the guided wavelengths corresponding to the frequencies F0, F1, F2. Experience has shown that when the inductive component, determined by A - a, and the capacitive component, determined by B - b, of the impedance in the plane P of the frame, are equal, at the frequency F0, the window 4 - 5 presents, in the plane P, a symmetrical susceptance with respect to the axis of the reals (axis of pure resistances) and passing through the middle (1, 0) of this axis on the Smith chart. FIG. 3 is a representation of this susceptance curve in a Smith chart where the direction of the source to charge displacement has been indicated by an arrow Ch. The susceptance varies regularly as a function of frequency; it passes successively through pure inductive values, zero for FO and pure capacitive, in the increasing direction of the frequencies of the band F1 - F2. The adaptation is therefore correct only for the frequency F0; to carry out the adaptation in the entire band F1 - F2 it is proposed to add a half-wave transformer and thus to carry out a broadband adaptation. Figures 4 to 11 show how such a matching transformer can be used and what this results for the susceptance curve (Figure 7).

Les figures 4, 5 et 6 montrent comment le guide selon les figures 1 et 2 peut être modifié pour lui incorporer un transformateur d'adaptation d'impédance du type demi-onde. Les figures 4 et 5 ne diffèrent respectivement des figures 1 et 2 que par le fait que la distance entre les moulures 2 et 3 a été réduite sur une longueur L = À 0/2 de part et d'autre de la fenêtre étanche 4 - 5, pour passer de l'écartement D à l'écartement d; les tronçons de moulures, tous de même longueur, situés de part et d'autre de la fenêtre 4 - 5 portent les références 20 et 21 pour la moulure 2 et 30 et 31 pour la moulure 3. La figure 6 a été donnée en complément aux figures 4 et 5 pour permettre de mieux comprendre comment était réalisé le guide; il s'agit d'une vue en coupe transversale par le plan de symétrie du guide qui est parallèle aux grands côtés du guide.Figures 4, 5 and 6 show how the guide according to Figures 1 and 2 can be modified to incorporate a half-wave type impedance matching transformer. Figures 4 and 5 differ from Figures 1 and 2 respectively only in that the distance between the moldings 2 and 3 has been reduced over a length L = 0/2 on either side of the sealed window 4 - 5, to pass from the spacing D to the spacing d; the molding sections, all of the same length, located on either side of the window 4 - 5 bear the references 20 and 21 for the molding 2 and 30 and 31 for the molding 3. FIG. 6 has been given in addition Figures 4 and 5 to allow a better understanding of how the guide was made; it is a cross-sectional view through the plane of symmetry of the guide which is parallel to the long sides of the guide.

Sur la figure 4 trois plans d'observation du guide ont été indiqués: plan P1 situé contre le transformateur d'impédance constitué par les tronçons de moulures rapprochés qui s'étendent sur la longueur L = λ0/2, du côté de la source couplée au guide, plan P2 situé contre le transformateur d'impédance mais du côté opposé à la source et plan P situé au niveau de la fenêtre 4 - 5.In FIG. 4, three observation planes of the guide have been indicated: plane P1 situated against the impedance transformer formed by the sections of close moldings which extend over the length L = λ0 / 2, on the side of the coupled source in the guide, plane P2 located against the impedance transformer but on the side opposite the source and plane P located at the level of window 4 - 5.

Comme indiqué sur l'abaque de la figure 7, avant et contre le plan d'observation P1, la fenêtre 4 - 5 présente la courbe (1) de susceptance qui correspond à la courbe de la figure 3 après une rotation de 180° autour du point 3 de coordonnées (1, 0) qui est due au transformateur.As indicated on the abacus of figure 7, before and against the observation plane P1, window 4 - 5 presents the curve (1) of susceptance which corresponds to the curve of figure 3 after a rotation of 180 ° around from point 3 of coordinates (1, 0) which is due to the transformer.

Après et contre le plan d'observation P1, la courbe (1) de la figure 7 subit une translation résistive, fonction de l'écartement d, et devient la courbe (2). Si cp désigne l'angle dont le sommet est le point J et dont les côtés passent par les extrémités de la courbe (2) relatives aux fréquences F1 et F2, la valeur de l'écartement d du transformateur demi-onde est ajustée afin que cet angle (p soit égal à la différence de rotation (vers la charge: flèche Ch) des points représentatifs des fréquences F1 et F2 le long du transformateur, c'est-à-dire que:After and against the observation plane P1, the curve (1) of FIG. 7 undergoes a resistive translation, function of the spacing d, and becomes the curve (2). If cp designates the angle whose apex is point J and whose sides pass through the ends of the curve (2) relating to frequencies F1 and F2, the value of the spacing d of the half-wave transformer is adjusted so that this angle (p is equal to the difference in rotation (towards the load: arrow Ch) of the points representative of the frequencies F1 and F2 along the transformer, that is to say that:

Figure imgb0001
Figure imgb0001

Le tronçon de guide de longueur L se comporte alors comme un espace de regroupement; dans le plan d'observation P2, après une rotation vers la charge sur un cercle à R. O. S. (rapport d'ondes stationnaires) constant du diagramme de Smith, tous les points relatifs aux différentes fréquences de la bande, se regroupent en 1, puis en J après ce même plan; ainsi l'adaptation est obtenue pour toutes les fréquences de la bande F1 - F2.The guide section of length L then behaves like a grouping space; in the observation plane P2, after a rotation towards the load on a circle with ROS (standing wave ratio) constant of the Smith diagram, all the points relating to the different frequencies of the band, are grouped in 1, then in J after this same plan; thus the adaptation is obtained for all the frequencies of the band F1 - F2.

Il est à observer que la fenêtre 4 - 5 doit satisfaire non seulement au problème d'adaptation mais aussi à celui du rejet des résonances parasites en dehors de la bande des fréquences de fonctionnement du guide à moulures. Pour trouver une solution permettant le rejet de ces fréquences parasites, l'expérience montre qu'il n'est pas possible de prendre, comme valeur b de la petite dimension de la plaque 4, la valeur pour laquelle la plaque en diélectrique n'occasionne aucune variation de capacité le long de la ligne de transmission que constitue le guide 1. Dans ce cas, en effet, la grande dimension, a, du cadre métallique 5, devrait être égale à la largeur intérieure, A, du guide à moulures, de manière à ne pas faire un apport selfique qui ne serait pas contrebalancé par un apport capacitif; or le volume de la plaque 4 serait alors assez important pour introduire des résonances parasites (ghost modes dans la littérature anglosaxonne) dans la bande passante du guide à moulures; il faut donc donner à la petite dimension de la plaque une valeur b suffisamment réduite par rapport à la valeur qui n'occasionnerait aucune variation de capacité le long de la ligne de transmission. Cette réduction qui fait apparaître une composante capacitive doit être annulée par un apport selfique correspondant qui est fonction de la valeur A - a (figure 5). Il est à noter que la réduction de b dont il vient d'être question ne doit pas être excessive car sinon l'apport selfique nécessaire à l'annulation de l'apport capacitif devient important, ce qui augmente la sélectivité du guide à fenêtre et est donc incompatible avec l'adaptation à large bande qui est recherchée.It should be noted that window 4 - 5 must satisfy not only the problem of adaptation but also that of the rejection of parasitic resonances outside the band of operating frequencies of the molding guide. To find a solution allowing the rejection of these parasitic frequencies, experience shows that it is not possible to take, as the value b of the small dimension of the plate 4, the value for which the dielectric plate does not cause no variation in capacity along the transmission line that constitutes the guide 1. In this case, in fact, the large dimension, a, of the metal frame 5, should be equal to the internal width, A, of the guide with moldings, so as not to make a selfic contribution which would not be counterbalanced by a capacitive contribution; however, the volume of the plate 4 would then be large enough to introduce parasitic resonances (ghost modes in Anglo-Saxon literature) into the bandwidth of the molding guide; it is therefore necessary to give the small size of the plate a value b which is sufficiently reduced compared to the value which would not cause any variation in capacity along the transmission line. This reduction which reveals a capacitive component must be canceled by a corresponding inductive contribution which is a function of the value A - a (FIG. 5). It should be noted that the reduction of b which has just been mentioned must not be excessive because otherwise the inductive contribution necessary for the cancellation of the capacitive contribution becomes significant, which increases the selectivity of the window guide and is therefore incompatible with the broadband adaptation which is sought.

A titre d'exemple, il a été réalisé un guide selon les figures 4 à 6, avec:

  • A = 17,55 mm B = 8,15 mm et largeur de moulure de 4,395 mm (guide type WRD 750 D 24)
  • a = 12,7 mm b=6,7mm
  • D = 3,45 mm d = 3 mm
  • longueur du transformateur 5,7 mm de part et d'autre de la fenêtre
  • plaque 4 en alumine d'une épaisseur de 0,5 mm,
  • cadre 5 en ferronickel d'une épaisseur de 1,5 mm, les résultats obtenus sont les suivants:
  • bande Fl - F2: 7,4 à 18,2 GHz
  • fréquence de la première résonance parasite: 18,4 GHz
  • R. 0. S. dans la bande F1 - F2 : 1,30
  • R. 0. S. à 7 GHz: 1,5.
By way of example, a guide has been produced according to FIGS. 4 to 6, with:
  • A = 17.55 mm B = 8.15 mm and molding width of 4.395 mm (guide type WRD 750 D 24)
  • a = 12.7 mm b = 6.7 mm
  • D = 3.45mm d = 3mm
  • length of transformer 5.7 mm on either side of the window
  • alumina plate 4 with a thickness of 0.5 mm,
  • frame 5 made of ferronickel with a thickness of 1.5 mm, the results obtained are as follows:
  • band F1 - F2: 7.4 to 18.2 GHz
  • frequency of the first parasitic resonance: 18.4 GHz
  • R. 0. S. in the band F1 - F2: 1.30
  • R. 0. S. at 7 GHz: 1.5.

Un autre exemple de guide à fenêtre étanche selon l'invention est représenté sur les figures 8 et 9. La figure 8 est une coupe longitudinale d'un guide d'ondes rectangulaire, 1, à moulures, 2, 3, par un plan perpendiculaire aux grands côtés du guide. La figure 9 est une vue en coupe transversale par un plan dont la trace, YY, est indiquée sur la figure 8. Une fenêtre constituée par un cadre métallique 5 et une plaque en diélectrique 4, est disposée dans un plan transversale du guide, sensiblement au milieu d'un transformateur demi-onde. Des tronçons de moulures, dont l'écartement est plus faible que l'écartement des moulures dans le reste du guide d'ondes 1, apparaissent sur la figure 8; ces tronçons constituent le transformateur demi-onde. Ce guide à fenêtre se distingue de celui selon les figures 4 à 6 par la façon dont est réalisée sa fenêtre; en effet, alors que dans le cas précédent le cadre 5 était usiné, cette fois-ci il est obtenu par emboutissage, ce qui, pour une réalisation en série, permet de réduire le coût; par ailleurs, toujours avec le souci de faciliter la réalisation de la fenêtre, il a été donné, à l'ouverture du cadre 5 et au pourtour de la plaque 4, la forme d'un rectangle sur les deux petits côtés duquel auraient été accolés respectivement deux demi-cercles de diamètre égal à la longueur des petits côtés du rectangle. Ce guide à fenêtre qui, à la forme près de sa fenêtre, correspond au guide des figures 4 à 6, a permis d'obtenir les mêmes résultats en ce qui concerne la transmission des ondes et la résistance mécanique de la fenêtre.Another example of a sealed window guide according to the invention is shown in FIGS. 8 and 9. FIG. 8 is a longitudinal section of a rectangular waveguide, 1, with moldings, 2, 3, by a perpendicular plane. at the long sides of the guide. Figure 9 is a cross-sectional view through a plane whose trace, YY, is indicated in Figure 8. A window consisting of a metal frame 5 and a dielectric plate 4, is arranged in a transverse plane of the guide, substantially in the middle of a half-wave transformer. Molding sections, the spacing of which is smaller than the spacing of the moldings in the rest of the waveguide 1, appear in FIG. 8; these sections constitute the half-wave transformer. This window guide differs from that according to FIGS. 4 to 6 by the way in which its window is produced; indeed, while in the previous case the frame 5 was machined, this time it is obtained by stamping, which, for a production in series, makes it possible to reduce the cost; moreover, still with the concern of facilitating the production of the window, it was given, at the opening of the frame 5 and around the plate 4, the shape of a rectangle on the two short sides of which would have been joined respectively two semicircles of diameter equal to the length of the short sides of the rectangle. This window guide which, in the shape close to its window, corresponds to the guide in FIGS. 4 to 6, has made it possible to obtain the same results with regard to the transmission of waves and the mechanical resistance of the window.

Les deux exemples qui viennent d'être décrits, concernaient des fenêtres disposées dans un plan transversal du guide à moulures et munies d'une plaque de diélectrique, 4, de forme oblongue dont la plus grande dimension était parallèle aux grands côtés du guide afin d'égaliser les apports selfiques et les apports capacitifs dus à la présence de cette plaque de diélectrique. Dans le cas où la plaque de diélectrique ne serait plus de forme oblongue mais serait circulaire il n'y aurait plus possibilité d'égaliser les apports capacitifs et selfiques, ces derniers étant toujours prépondérants; dans ce cas il n'est pas possible d'obtenir un rapport d'ondes stationnaires inférieur à 2, même dans une bande réduite aux deux tiers de la bande passante du guide. Par contre il est possible d'incliner la fenêtre circulaire pour qu'elle se comporte comme une fenêtre oblongue; en effet, lorsque la projection de la plaque de diélectrique sur un plan transversal du guide a une forme oblongue dont la plus grande dimension est parallèle aux grands côtés du guide, il est possible d'égaliser les apports selfiques et les apports capacitifs.The two examples which have just been described relate to windows arranged in a transverse plane of the molding guide and provided with a dielectric plate, 4, of oblong shape, the largest dimension of which was parallel to the long sides of the guide in order to '' equalize the inductive contributions and the capacitive contributions due to the presence of this dielectric plate. In the case where the dielectric plate would no longer be oblong in shape but would be circular there would no longer be the possibility of equalizing the capacitive and inductive contributions, the latter being always preponderant; in this case it is not possible to obtain a standing wave ratio of less than 2, even in a band reduced to two thirds of the pass band of the guide. On the other hand, it is possible to tilt the circular window so that it behaves like an oblong window; in fact, when the projection of the dielectric plate on a transverse plane of the guide has an oblong shape, the largest dimension of which is parallel to the long sides of the guide, it is possible to equalize the inductive contributions and the capacitive contributions.

Les figures 10 et 11 montrent un guide selon l'invention, comportant une fenêtre inclinée 4 - 5, à plaque en diélectrique circulaire 4 et cadre métallique 5. La figure 10, qui est une vue en coupe longitudinale par le plan de symétrie du guide qui est perpendiculaire aux grands côtés du guide, montre le guide 1 avec ses moulures 2, 3 qui, sur un longueur L, sont rapprochées pour former un transformateur d'adaptation. La figure 11 est une vue en coupe transversale du guide, par un plan dont la trace ZZ est représentée sur la figure 10; cette figure montre que, dans le plan de coupe, l'ellipse de projection de la plaque 4 a son grand axe, non représenté, parallèle aux grands côtés du guide.FIGS. 10 and 11 show a guide according to the invention, comprising an inclined window 4 - 5, with a circular dielectric plate 4 and metallic frame 5. FIG. 10, which is a view in longitudinal section through the plane of symmetry of the guide which is perpendicular to the long sides of the guide, shows the guide 1 with its moldings 2, 3 which, over a length L, are brought together to form an adaptation transformer. Figure 11 is a cross-sectional view of the guide, through a plane whose trace ZZ is shown in Figure 10; this figure shows that, in the section plane, the projection ellipse of the plate 4 has its major axis, not shown, parallel to the long sides of the guide.

Dans les trois exemples de réalisation qui ont été décrits à l'aide des figures 4 à 6 et 8 à 11, la plaque en céramique 4 est fixée sur le cadre en ferronickel 5 par brasage sur plat, c'est-à-dire que la brasure disposée entre la plaque 4 et le cadre 5, est en contact avec la plaque uniquement sur une des faces de celle-ci et forme un cordon refermé sur lui-même dont le bord extérieur épouse le bord de la face considérée. Tout autre mode de fixation est envisageable dans la mesure où il assure la solidité et l'étanchéité de la fenêtre: brasage sur le champ de la plaque ou combinaison d'un brasage sur champ avec un brasage sur plat, ou collage... Il est de plus à noter que, pour faciliter le brasage de la plaque en céramique sur le cadre, il peut être intéressant d'interrompre les moulures un peu avant la fenêtre, par exemple sur un à cinq dizièmes de millimètre.In the three exemplary embodiments which have been described with the aid of FIGS. 4 to 6 and 8 to 11, the ceramic plate 4 is fixed to the ferronickel frame 5 by brazing on a plate, that is to say that the solder disposed between the plate 4 and the frame 5, is in contact with the plate only on one of the faces thereof and forms a cord closed on itself whose outer edge matches the edge of the face considered. Any other method of attachment is possible insofar as it ensures the solidity and sealing of the window: brazing on the field of the plate or combination of brazing on the field with brazing on a plate, or bonding ... It should also be noted that, to facilitate the brazing of the ceramic plate on the frame, it may be advantageous to interrupt the moldings a little before the window, for example on one to five tenths of a millimeter.

La présente invention n'est pas limitée aux exemples décrits, c'est ainsi que, pour l'ouverture, toute forme oblongue ou à projection transversale oblongue peut convenir dans la mesure où elle permet d'équilibrer les apports capacitifs et selfiques. De même, s'il est indispensable que la fenêtre 4 - 5 soit située dans la zone du transformateur d'impédance (tronçons de moulures 20, 21, 30, 31 de la figure 4), par contre il n'est pas nécessaire qu'elle soit au milieu de cette zone, ni que les moulures du guide soient symétriques, même dans la zone du transformateur d'impédance; d'ailleurs un guide à une seule moulure convient pour réaliser un guide à fenêtre selon l'invention.The present invention is not limited to the examples described, this is how, for the opening, any oblong shape or oblong transverse projection can be suitable insofar as it makes it possible to balance the capacitive and inductive inputs. Similarly, if it is essential that the window 4 - 5 is located in the area of the impedance transformer (sections of moldings 20, 21, 30, 31 in FIG. 4), on the other hand it is not necessary that 'it is in the middle of this area, nor that the guide moldings are symmetrical, even in the area of the impedance transformer; moreover, a guide with a single molding is suitable for producing a window guide according to the invention.

La présente invention est tout particulièrement applicable à la réalisation de fenêtres hyperfréquences de puissance, capables de travailler dans une bande de fréquences supérieure à une octave sans fréquences parasites dans la bande de fonctionnement.The present invention is very particularly applicable to the production of microwave power windows, capable of working in a frequency band greater than one octave without parasitic frequencies in the operating band.

Claims (7)

1. A rectangular waveguide (1) having ridges (2, 3) and a tight window (4, 5), characterized in that the window (4, 5) is a thin window, i. e. a window, whose dielectric has a thickness which represents an electrical length that is at least five times smaller than the length of the guided wave, which corresponds to the highest operational frequency in the guide, that the window is composed of a metal frame (5) and a dielectric disk (4), the frame being provided with an opening and the disk closing said opening, that the opening, when projected onto a transversal plane, has an elongated shape, whose largest extension is parallel to the large sides of the guide and whose overall dimensions, lying parallel respectively to the large and to the small sides of the guide, are respectively smaller than the dimensions of the large sides (A) and of the small sides (B) of the guide, and in that the waveguide comprises a matching transformer (20 - 21, 30 - 31) disposed within a zone (L) on both sides of the window (4, 5), said transformer being obtained in giving to the ridges (2, 3) of the guide a height which is, compared to the wall on which the ridges are formed, larger in said zone than outside the zone.
2. A guide according to claim 1, characterized in that the window (4, 5) is disposed within a transversal plane of the guide (1).
3. A guide according to claim 2, characterized in that the disk (4) has the shape of a rectangle whose small sides are rounded (Fig. 5).
4. A guide according to claim 2, characterized in that the disk has the shape of a rectangle, with two half-circle sectors added to its two small sides, respectively, these sectors having a diameter equal to the length of the small sides of the rectangle (Fig. 9).
5. A guide according to claim 1, characterized in that the window (4, 5) is inclined in relation to a transversal plane of the guide (Fig. 10, 11).
6. A guide according to claim 5, characterized in that the disk (4) is circular in shape (Fig. 10, 11).
7. A guide according to claim 4, characterized in that the frame is obtained through punching.
EP85402616A 1984-12-28 1985-12-24 Ridged waveguide with a fluid-tight window Expired EP0189712B1 (en)

Applications Claiming Priority (2)

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FR8419997 1984-12-28
FR8419997A FR2575604B1 (en) 1984-12-28 1984-12-28 RECTANGULAR MOLDED WAVEGUIDE WITH WATERPROOF WINDOW

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EP0189712B1 true EP0189712B1 (en) 1989-08-02

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JPS61158202A (en) 1986-07-17
EP0189712A1 (en) 1986-08-06
US4720693A (en) 1988-01-19
FR2575604B1 (en) 1987-01-30
FR2575604A1 (en) 1986-07-04

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