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EP0045242A1 - Microwave pass-band filter in a waveguide - Google Patents

Microwave pass-band filter in a waveguide Download PDF

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Publication number
EP0045242A1
EP0045242A1 EP81401153A EP81401153A EP0045242A1 EP 0045242 A1 EP0045242 A1 EP 0045242A1 EP 81401153 A EP81401153 A EP 81401153A EP 81401153 A EP81401153 A EP 81401153A EP 0045242 A1 EP0045242 A1 EP 0045242A1
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EP
European Patent Office
Prior art keywords
bandpass filter
waveguide
section
filter
resonant
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP81401153A
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German (de)
French (fr)
Inventor
Gilles Sillard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thomson CSF SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0045242A1 publication Critical patent/EP0045242A1/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/207—Hollow waveguide filters

Definitions

  • the invention relates to a microwave bandpass filter made as a waveguide and having a very small footprint.
  • a bandpass filter is a device allowing the transmission, without power attenuation, of a signal whose frequency is located in a determined frequency band, but strongly attenuating the power of signals whose frequency is outside this band.
  • a microwave bandpass filter produced as a waveguide is constituted either by a series of resonators coupled together or by a series of resonant iris generally connected together.
  • these are coupled either by transmission lines or directly.
  • a resonator being produced from a transmission line closed at its two ends by susceptances, the value and the length of the line are determined as a function of the overvoltage coefficient, the different resonators constituting the filter are coupled either by transmission lines each placed between the susceptances of two resonators and of length equal to a quarter of the wavelength at the resonant frequency, or directly.
  • a resonator is coupled to the adjacent resonator by a single susceptance of determined value equivalent to the two extreme susceptances of the two resonators and to the coupling line.
  • a susceptance is achieved using bars or metal shutters located in a straight section of the guide, symmetrically on either side of the median axis of the section or by a central flap.
  • the frequency response of the filter is fixed by the distribution of the overvoltage coefficients of the various resonators constituting it.
  • a bandpass filter can also be constituted by a series of resonant irises, as has been said before, coupled together by transmission lines of length equal to a quarter of the wavelength at the center frequency of the filter operating band.
  • the dimensions of these irises are such that at their resonant frequency, the largest of these dimensions is equal to half the wavelength ⁇ .
  • a drawback of this kind of filter is the excessively large dimensions due to the transmission lines which the object of the invention aims to remedy.
  • the microwave bandpass filter produced as a waveguide is formed in a single cross section of the guide by at least one resonant window whose dimensions and position relative to two orthogonal planes of symmetry of the window depends on the width of the filter bandwidth.
  • This kind of filter is very bulky. This is why the invention aims to remedy this by producing a bandpass filter of considerably reduced dimensions as shown in FIG. 2, for example.
  • This waveguide filter consists, in a single cross section 8 of the guide 9, by a resonant window 10 whose shape is given by way of example and is not limiting.
  • the dimensions, in this case I 1 , I 2 , I 3 , h 1 and h 2 , as well as the position of the window relative to the two orthogonal planes of symmetry ⁇ 3 and ⁇ 4 determine the filter overvoltage coefficient .
  • This resonant window 10 therefore plays the role of a series of conventional resonators coupled together, or of resonant irises also coupled together by transmission lines, of the prior art.
  • FIG. 6 represents the response curves of two filters, produced according to the invention, the curve CI corresponding to a filter produced with a single resonant window and the curve C 2 corresponding to a filter having two windows in the same cross section of the guide. It can be seen that the width of the passband is greater in the case of the curve C2.

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Abstract

Filter constituted, in a single cross-section (8) of the guide, by at least one resonant window (10) whose shape determines the width of the pass band of the filter. Application to staggered circuit band-pass filters. <IMAGE>

Description

L'invention concerne un filtre passe-bande hyperfréquence réalisé en guide d'ondes et présentant un très faible encombrement.The invention relates to a microwave bandpass filter made as a waveguide and having a very small footprint.

Un filtre passe-bande est un dispositif permettant la transmission, sans atténuation de puissance, d'un signal dont la fréquence se situe dans une bande de fréquences déterminée, mais atténuant fortement la puissance de signaux dont la fréquence est hors de cette bande.A bandpass filter is a device allowing the transmission, without power attenuation, of a signal whose frequency is located in a determined frequency band, but strongly attenuating the power of signals whose frequency is outside this band.

Généralement, un filtre passe-bande hyperfréquence réalisé en guide d'ondes est constitué soit par une série de résonateurs couplés entre eux soit par une série d'iris résonnants généralement reliés entre eux. Dans le cas où il est constitué par des résonateurs, ceux- ci sont couplés soit par des lignes de transmission soit directement. En effet, un résonateur étant réalisé à partir d'une ligne de transmission fermée à ses deux extrémités par des susceptances, dont la valeur ainsi que la longueur de la ligne sont déterminées en fonction du coefficient de surtension, les différents résonateurs constituant le filtre sont couplés soit par des lignes de transmission placées chacune entre les susceptances de deux résonateurs et de longueur égale au quart de la longueur d'onde à la fréquence de résonance, soit directement. Dans ce dernier cas, un résonateur est couplé au résonateur adjacent par une seule susceptance de valeur déterminée équivalente aux deux susceptances extrêmes des deux résonateurs et à la ligne de couplage. Une susceptance est réalisée à l'aide de barreaux ou de volets métalliques situés dans une section droite du guide, symétriquement de part et d'autre de l'axe médian de la section ou par un volet central. La réponse en fréquence du filtre est fixée par la répartition des coefficients de surtension des différents résonateurs le constituant.Generally, a microwave bandpass filter produced as a waveguide is constituted either by a series of resonators coupled together or by a series of resonant iris generally connected together. In the case where it is constituted by resonators, these are coupled either by transmission lines or directly. Indeed, a resonator being produced from a transmission line closed at its two ends by susceptances, the value and the length of the line are determined as a function of the overvoltage coefficient, the different resonators constituting the filter are coupled either by transmission lines each placed between the susceptances of two resonators and of length equal to a quarter of the wavelength at the resonant frequency, or directly. In the latter case, a resonator is coupled to the adjacent resonator by a single susceptance of determined value equivalent to the two extreme susceptances of the two resonators and to the coupling line. A susceptance is achieved using bars or metal shutters located in a straight section of the guide, symmetrically on either side of the median axis of the section or by a central flap. The frequency response of the filter is fixed by the distribution of the overvoltage coefficients of the various resonators constituting it.

Un filtre passe-bande peut aussi être constitué par une série d'iris résonnants, comme cela a été dit auparavant, couplés entre eux par des lignes de transmission de longueur égale au quart de la longeur d'onde à la fréquence centrale de la bande de fonctionnement du filtre.A bandpass filter can also be constituted by a series of resonant irises, as has been said before, coupled together by transmission lines of length equal to a quarter of the wavelength at the center frequency of the filter operating band.

Les dimensions de ces iris sont telles qu'à leur fréquence de résonance, la plus grande de ces dimensions est égale à la moitié de la longueur d'onde À.The dimensions of these irises are such that at their resonant frequency, the largest of these dimensions is equal to half the wavelength λ.

Un inconvénient de ce genre de filtre est le trop fort encombrement dû aux lignes de transmission que l'objet de l'invention vise à remédier.A drawback of this kind of filter is the excessively large dimensions due to the transmission lines which the object of the invention aims to remedy.

Suivant une caractéristique de l'invention, le filtre passe-bande hyperfréquence réalisé en guide d'ondes est constitué dans une seule section droite du guide par au moins une fenêtre résonnante dont les dimensions et la position par rapport à deux plans de symétrie orthogonaux de la fenêtre sont fonction de la largeur de la bande passante du filtre.According to a characteristic of the invention, the microwave bandpass filter produced as a waveguide is formed in a single cross section of the guide by at least one resonant window whose dimensions and position relative to two orthogonal planes of symmetry of the window depends on the width of the filter bandwidth.

D'autres caractéristiques et avantages de l'invention apparaîtront dans la description qui suit illustrée par les figures suivantes représentant :

  • - la figure 1 : Un filtre passe-bande constitué par une série de résonateurs couplés entre eux, selon l'art antérieur ;
  • - Les figures 2 à 5 : Plusieurs types de réalisation d'un filtre passe-bande selon l'invention.
  • - La figure 6 : Les courbes de résonance de plusieurs filtres selon l'invention.
  • - La figure 1 représente un filtre passe-bande hyperfréquence, selon l'art antérieur. Il est constitué par au moins deux résonateurs 1 et 2 couplés entre eux par une ligne de transmission 3 de longueur L égale àλ/4 à la fréquence centrale de la bande de fonctionnement du filtre. Chaque résonateur 1 ou 2 est constitué par une ligne de transmission 4 OU 5 fermée à ses deux extrémités par des susceptances réalisées à l'aide de volets 6 métalliques. Sur la figure 1, le guide d'ondes 7 a une section droite rectangulaire et les volets sont placés symétriquement par rapport aux deux plans de symétrie π1 et π2 orthogonaux.
Other characteristics and advantages of the invention will appear in the description which follows, illustrated by the following figures representing:
  • - Figure 1: A bandpass filter consisting of a series of resonators coupled together, according to the prior art;
  • - Figures 2 to 5: Several types of embodiment of a bandpass filter according to the invention.
  • - Figure 6: The resonance curves of several filters according to the invention.
  • - Figure 1 shows a microwave bandpass filter, according to the prior art. It consists of at least two resonators 1 and 2 coupled together by a transmission line 3 of length L equal to λ / 4 at the central frequency of the operating band of the filter. Each resonator 1 or 2 is constituted by a transmission line 4 OR 5 closed at its two ends by susceptances produced using metal shutters 6. In FIG. 1, the waveguide 7 has a rectangular cross section and the flaps are placed symmetrically with respect to the two orthogonal planes of symmetry π 1 and π 2 .

Comme cela a été déjà mentionné, ce genre de filtre est très encombrant. C'est pourquoi l'invention vise à y remédier en réalisant un filtre passe-bande de dimensions considérablement réduites comme le montre la figure 2, par exemple. Ce filtre en guide d'ondes est constitué, dans une seule section droite 8 du guide 9, par une fenêtre résonnante 10 dont la forme est donnée à titre d'exemple et n'est pas limitative. Les dimensions, en l'occurence I1, I2, I3, h1 et h2, ainsi que la position- de la fenêtre par rapport aux deux plans de symétrie π3 et π4 orthogonaux déterminent le coefficient de surtension du filtre. Cette fenêtre résonnante 10 joue donc le rôle d'une série de résonateurs classiques couplés entre eux, ou d'iris résonnants couplés également entre eux par des lignes de transmission, de l'art antérieur.As already mentioned, this kind of filter is very bulky. This is why the invention aims to remedy this by producing a bandpass filter of considerably reduced dimensions as shown in FIG. 2, for example. This waveguide filter consists, in a single cross section 8 of the guide 9, by a resonant window 10 whose shape is given by way of example and is not limiting. The dimensions, in this case I 1 , I 2 , I 3 , h 1 and h 2 , as well as the position of the window relative to the two orthogonal planes of symmetry π 3 and π 4 determine the filter overvoltage coefficient . This resonant window 10 therefore plays the role of a series of conventional resonators coupled together, or of resonant irises also coupled together by transmission lines, of the prior art.

Pour élargir la bande passante du filtre, il est possible d'abaisser le coefficient de surtension en réalisant au moins deux fenêtres résonnantes 11 et 12 dans la même section droite du guide d'ondes, comme le montre la figure 3. Les remarques concernant la forme et la position des fenêtres restent les mêmes que pour la figure précédente et pour les figures suivantes. Les figures 4 et 5 donnent d'autres exemples non limitatifs de fenêtres résonnantes, dont la forme et les dimensions sont fonction de la bande passante. choisie pour le filtre.To widen the bandwidth of the filter, it is possible to lower the overvoltage coefficient by making at least two resonant windows 11 and 12 in the same cross section of the waveguide, as shown in Figure 3. The remarks concerning the shape and position of the windows remain the same as for the previous figure and for the following figures. Figures 4 and 5 give other non-limiting examples of resonant windows, the shape and dimensions of which depend on the bandwidth. chosen for the filter.

On peut également réaliser un filtre passe-bande à circuits décalés en plaçant toujours dans une seule et même section-droite du guide, plusieurs fenêtres résonnantes présentant des fréquences de résonance différentes. La courbe de transmission d'un tel filtre est alors l'enveloppe des courbes de réponse des différentes fenê- tres.It is also possible to produce a bandpass filter with offset circuits by always placing in a single straight section of the guide, several resonant windows having different resonant frequencies. In such a filter transmission curve is the envelope of the response curves of the various FENE - tres.

A titre d'exemple, la figure 6 représente les courbes de réponse de deux filtres, réalisés selon l'invention, la courbe CI correspondant à un filtre réalisé avec une seule fenêtre résonnante et la courbe C2 correspoindant à un filtre ayant deux fenêtres dans la même section droite du guide. On constate que la largeur de la bande passante est supérieure dans le cas de la courbe C2.By way of example, FIG. 6 represents the response curves of two filters, produced according to the invention, the curve CI corresponding to a filter produced with a single resonant window and the curve C 2 corresponding to a filter having two windows in the same cross section of the guide. It can be seen that the width of the passband is greater in the case of the curve C2.

Ainsi, on a décrit un filtre passe-bande réalisé en guide d'ondes, d'une réalisation mécanique très simple et d'un encombrement très réduit par rapport à ceux de l'art antérieur, puisqu'il ne comporte plus de 'lignes de transmission situées entre les résonateurs, et que les fenêtres résonnantes le constituant peuvent être réalisées dans une plaque métallique ayant une épaisseur de quelques dizièmes de millimètres.Thus, a bandpass filter produced as a guide has been described. of waves, of a very simple mechanical construction and of a very reduced bulk compared to those of the prior art, since it no longer comprises any 'transmission lines situated between the resonators, and only the resonant windows the constituent can be made in a metal plate having a thickness of a few tenths of a millimeter.

A cela, s'ajoute le fait que les pertes de puissance sont réduites et que la réalisation de tels filtres peut se faire dans des guides d'ondes rectangulaires ou circulaires et dans toutes les gammes de fréquence.Added to this is the fact that the power losses are reduced and that the production of such filters can be done in rectangular or circular waveguides and in all frequency ranges.

Claims (4)

1. Filtre passe-bande hyperfréquence réalisé en guide d'ondes caractérisé en ce qu'il est constitué dans une seule section droite (8) du guide (9) par au moins une fenêtre résonnante (10) dont les dimensions et la position par rapport à deux plans de symétrie orthogonaux de la fenêtre sont déterminées par la largeur de la bande passante du filtre.1. Microwave bandpass filter produced as a waveguide characterized in that it is constituted in a single straight section (8) of the guide (9) by at least one resonant window (10) whose dimensions and position by relative to two orthogonal planes of symmetry of the window are determined by the width of the passband of the filter. 2. Filtre passe-bande selon la revendication 1, caractérisé en ce que les différentes fenêtres résonnantes (11 et 12) placées dans la section droite du guide sont telles qu'elles ont la même fréquence de résonance.2. Bandpass filter according to claim 1, characterized in that the different resonant windows (11 and 12) placed in the cross section of the guide are such that they have the same resonant frequency. 3. Filtre passe-bande selon la revendication 1, caractérisé en ce que les différentes fenêtres résonnantes placées dans la section droite du guide ont des fréquences de résonance différentes, réalisant un filtre passe-bande à circuits décalés.3. Bandpass filter according to claim 1, characterized in that the different resonant windows placed in the cross section of the guide have different resonant frequencies, producing a bandpass filter with offset circuits. 4. Filtre passe-bande selon la revendication 1, caractérisé en ce que le guide d'onde (9) à une section droite rectangulaire ou circulaire.4. Bandpass filter according to claim 1, characterized in that the waveguide (9) has a rectangular or circular cross section.
EP81401153A 1980-07-22 1981-07-21 Microwave pass-band filter in a waveguide Withdrawn EP0045242A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8016130A FR2487587A1 (en) 1980-07-22 1980-07-22 HYPERFREQUENCY BANDWIDTH FILTER REALIZED IN A WAVEGUIDE
FR8016130 1980-07-22

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EP0045242A1 true EP0045242A1 (en) 1982-02-03

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FR (1) FR2487587A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4680561A (en) * 1984-05-30 1987-07-14 Nec Corporation Microwave waveguide filter having a metal plate which includes a resonant aperture therein
EP0260633A1 (en) * 1986-09-18 1988-03-23 Alcatel Telspace E-plane-type compound filter
EP0320268A1 (en) * 1987-12-10 1989-06-14 Nec Corporation Waveguide band-pass filter
US6104262A (en) * 1998-10-06 2000-08-15 Hughes Electronics Corporation Ridged thick walled capacitive slot
ITMI20101848A1 (en) * 2010-10-08 2012-04-09 Tvc S P A ANTENNA DIPLEXER WITH A MINIATURIZED STRUCTURE

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB608254A (en) * 1944-11-14 1948-09-13 Csf Improvements relating to guides for radio-electric waves associated with elements for regulating the propagation of said waves
GB773527A (en) * 1953-10-09 1957-04-24 British Thomson Houston Co Ltd Improvements in and relating to waveguides
US3196339A (en) * 1960-06-23 1965-07-20 Microwave Ass Microwave harmonic generator and filter element therefor
FR2349968A1 (en) * 1976-04-27 1977-11-25 Thomson Csf Microwave guide with lateral access - has opening with slotted metal sheet to provide frequency multiplexing or de-multiplexing
EP0029276A1 (en) * 1979-11-15 1981-05-27 Staat der Nederlanden (Staatsbedrijf der Posterijen, Telegrafie en Telefonie) Microwave filter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB608254A (en) * 1944-11-14 1948-09-13 Csf Improvements relating to guides for radio-electric waves associated with elements for regulating the propagation of said waves
GB773527A (en) * 1953-10-09 1957-04-24 British Thomson Houston Co Ltd Improvements in and relating to waveguides
US3196339A (en) * 1960-06-23 1965-07-20 Microwave Ass Microwave harmonic generator and filter element therefor
FR2349968A1 (en) * 1976-04-27 1977-11-25 Thomson Csf Microwave guide with lateral access - has opening with slotted metal sheet to provide frequency multiplexing or de-multiplexing
EP0029276A1 (en) * 1979-11-15 1981-05-27 Staat der Nederlanden (Staatsbedrijf der Posterijen, Telegrafie en Telefonie) Microwave filter

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4680561A (en) * 1984-05-30 1987-07-14 Nec Corporation Microwave waveguide filter having a metal plate which includes a resonant aperture therein
EP0260633A1 (en) * 1986-09-18 1988-03-23 Alcatel Telspace E-plane-type compound filter
FR2604305A1 (en) * 1986-09-18 1988-03-25 Alcatel Thomson Faisceaux COMPOSITE WIDE-BAND TYPE-PLAN COMPOSITE FILTER
US4800349A (en) * 1986-09-18 1989-01-24 Alcatel Thomson Faisceaux E-plane type wide band composite filter
EP0320268A1 (en) * 1987-12-10 1989-06-14 Nec Corporation Waveguide band-pass filter
US6104262A (en) * 1998-10-06 2000-08-15 Hughes Electronics Corporation Ridged thick walled capacitive slot
ITMI20101848A1 (en) * 2010-10-08 2012-04-09 Tvc S P A ANTENNA DIPLEXER WITH A MINIATURIZED STRUCTURE

Also Published As

Publication number Publication date
FR2487587B1 (en) 1984-11-30
FR2487587A1 (en) 1982-01-29

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