EP0326498B1 - Resonant circuit and filter using it - Google Patents
Resonant circuit and filter using it Download PDFInfo
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- EP0326498B1 EP0326498B1 EP19890400242 EP89400242A EP0326498B1 EP 0326498 B1 EP0326498 B1 EP 0326498B1 EP 19890400242 EP19890400242 EP 19890400242 EP 89400242 A EP89400242 A EP 89400242A EP 0326498 B1 EP0326498 B1 EP 0326498B1
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- Prior art keywords
- filter
- resonator
- micro tape
- resonators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
- H01P1/20327—Electromagnetic interstage coupling
- H01P1/20354—Non-comb or non-interdigital filters
- H01P1/20381—Special shape resonators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P7/00—Resonators of the waveguide type
- H01P7/08—Strip line resonators
- H01P7/082—Microstripline resonators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P7/00—Resonators of the waveguide type
- H01P7/08—Strip line resonators
- H01P7/088—Tunable resonators
Definitions
- the present invention relates to a resonant circuit and a filter using this circuit.
- the technical field of the invention is radioelectricity, electronics, filtering and multiplexing of frequencies, etc.
- the invention finds a particular application in the construction of stations for receiving television signals broadcast by satellites.
- One of the problems posed in this technique is to produce, in the reception station, a filter operating in the frequency band 950-1750 MHz and making it possible to very easily rearrange the frequency plans, according to the availability of channels and user demand.
- the object of the present invention is precisely to remedy this deficiency by proposing a circuit and a filter which have all these advantages.
- Ring resonators which operate on the principle of establishing a standing wave regime.
- a conductive tape or microstrip is used, the length of which is equal to the wavelength associated with the resonant frequency (or possibly at half the wavelength).
- the shape of the ribbon is limited to a few simple shapes capable of leading to a high overvoltage. There are therefore in practice always circular rings or possibly U.
- the dimension of the circuit is, in essence, of the order of the wavelength. As soon as the frequency becomes low, the dimensions of the resonator become prohibitive. For example, at 30 MHz a resonator of the prior art constituted by a circular ribbon will have a diameter of 1.60 m.
- the object of the present invention is precisely to remedy these drawbacks. To this end, it recommends a resonant circuit still using a conductive tape but under very different operating conditions from those of the prior art.
- the ribbon plays the role of pure inductance in the band of use of the circuit. To do this, its length is taken less than ⁇ / 8, if ⁇ is the wavelength associated with the working frequency of the resonator.
- resonant loops comprising an interrupted microstrip loop of length ⁇ / 8 and a capacitor in the opening are already known from the prior art, see for example the document "1986 IEEE-MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST , Baltimore, Maryland, June 2-4, 1986, pages 411-414, IEEE, New York, US; M. MAKIMOTO et al .: 'Varactor tuned bandpass filters using microstrip-line ring resonators' ".
- the ribbon is a simple inductive element means that its shape is in no way critical. It is therefore possible to retain any desired shape, in particular shapes that allow the ribbon to be folded up to save space.
- the subject of the present invention is a filter comprising several resonant circuits as defined above. These circuits (identical or different) are coupled to each other.
- the coupling is tight, critical or loose depending on the case.
- shape of the ribbon is not critical, as has been pointed out above, we are free to choose the shape best suited to the chosen coupling.
- the invention thus finds a wide field of application. Filters from 30 MHz to 2 or 3 GHz can be produced. Bandwidth ranges from a few fractions of a percent to about 10%.
- a resonant circuit according to the invention is shown in Figure 1, in top view (a), in section (b) and in a variant with a metal case (c).
- This element comprises a planar substrate 10, made of dielectric material (for example epoxy glass, Teflon, etc.).
- a conductive layer 12 in copper for example
- a microstrip 14 made of conductive material ( copper for example).
- the circuit is arranged in a metal housing 20 and the ground plane is constituted by the metal walls 22 lower and upper.
- the microstrip draws an "open" outline in the sense that it incompletely surrounds part of the plane. In other words, it has at least one opening.
- this outline is rectangular and the opening (single) is referenced 16.
- Connected through this opening is a capacitor 18 adjustable or adjusted once and for all.
- FIG. 2 The equivalent electrical diagram is shown in FIG. 2, again considering the element in plan view (a) and in section (b) in the variant where the ground plane is arranged under the substrate.
- inductance L due to the non-rectilinear microstrip
- tuning capacitor Ca connected between the ends of the ribbon
- parasitic capacitors Cp which correspond to the volume separating the microstrip and the ground plan.
- l the length of the microstrip and by ⁇ the wavelength in the substrate at the operating frequency.
- the length l is always less than or equal to ⁇ / 8 in order to be able to be assimilated to an inductor independent of the frequency.
- the wavelength ⁇ o in the substrate corresponding to fo is determined, then the value of ⁇ o / 8 and a microstrip length less than this value is chosen.
- the value of the inductance L can be obtained approximately by the formula:
- the parasitic capacitance Cp value can be obtained by a formula of the type:
- the parameters of the resonant circuit are defined.
- the length of the coupled microstrip and the degree of coupling are determined experimentally.
- FIG. 5 shows a complete filter composed of five circuits C1 to C5 on a single substrate 10 with an input microstrip E and an output microstrip S.
- the filter of the invention uses a direct coupling at the input and output which performs the adaptation between the first and the last resonators and the circuits of use.
- the contours drawn by the microstrip are rectangular, two adjacent contours having two parallel sides. But one could also use triangular circuits for example mounted head to tail.
- circuits can be nested one inside the other.
- Figure 6 gives the main dimensions of an example filter designed to have a center frequency fo equal to 1131.620 MHz. Dimensions are in millimeters. The capacitors are adjustable from 0.5 to 5 pF. The substrate is made of 16/10 mm thick epoxy glass.
- the contours drawn by the microstrips are U-shaped, that is to say rectangles with one side missing.
- the orientation of these U alternates from one resonator to another, so that the capacitors are placed on both sides of the filter, sometimes at the top, sometimes at the bottom (in the sense of figure 6).
- Figures 7, 8 and 9 show the attenuation characteristic of a filter obtained according to the invention, with different frequency scales (on the abscissa).
- the curve goes from 1 to 2000 MHz; in FIG. 8, the width of the measurement band is 100 MHz; in Figure 9, it is 40 MHz.
- the curve in FIG. 10 represents the group time characteristic of the filter in nanoseconds by division.
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Description
La présente invention a pour objet un circuit résonnant et un filtre utilisant ce circuit. Le domaine technique de l'invention est la radioélectricité, l'électronique, le filtrage et le multiplexage de fréquences, etc...The present invention relates to a resonant circuit and a filter using this circuit. The technical field of the invention is radioelectricity, electronics, filtering and multiplexing of frequencies, etc.
L'invention trouve une application particulière dans la réalisation de stations de réception de signaux de télévision diffusés par satellites.The invention finds a particular application in the construction of stations for receiving television signals broadcast by satellites.
L'un des problèmes posés dans cette technique est de réaliser, dans la station de réception, un filtre fonctionnant dans la bande de fréquences 950-1750 MHz et permettant de réaménager très facilement les plans de fréquences, en fonction des disponibilités en canaux et de la demande des usagers.One of the problems posed in this technique is to produce, in the reception station, a filter operating in the frequency band 950-1750 MHz and making it possible to very easily rearrange the frequency plans, according to the availability of channels and user demand.
Parmi les nombreux types de filtres existants (du type à cellules LC couplées, hélicoïdaux, coaxiaux, à quartz, à guide d'onde, à résonateur diélectrique,...), il n'en existe pas qui présente à la fois un faible coût, une grande facilité de réglage, une bonne stabilité et une plage de fonctionnement allant de fréquences aussi basses que quelques dizaines de mégahertz à des fréquences supérieures à 2000 MHz.Among the many types of existing filters (of the type with coupled LC cells, helical, coaxial, quartz, waveguide, dielectric resonator, ...), there is none that has both a low cost, great ease of adjustment, good stability and an operating range from frequencies as low as a few tens of megahertz to frequencies above 2000 MHz.
La présente invention a justement pour but de remédier à cette carence en proposant un circuit et un filtre qui présentent tous ces avantages.The object of the present invention is precisely to remedy this deficiency by proposing a circuit and a filter which have all these advantages.
On connaît des résonateurs en anneau fonctionnant selon le principe de l'établissement d'un régime d'ondes stationnaires. Un ruban conducteur (ou micro-ruban) est utilisé dont la longueur est égale à la longueur d'onde associée à la fréquence de résonance (ou éventuellement à la demi-longueur d'onde).Ring resonators are known which operate on the principle of establishing a standing wave regime. A conductive tape (or microstrip) is used, the length of which is equal to the wavelength associated with the resonant frequency (or possibly at half the wavelength).
De tels résonateurs en anneau sont décrits par exemple dans l'article intitulé "On the Study of Microstrip Ring and Varactor-Tuned Ring Circuits'' publié dans la revue IEEE Transactions on Microwave Theory and Techniques, vol. MIT-35, n°12, Décembre 1987, pp. 1288-1294 ou encore dans le brevet des Etats-Unis d'Amérique US-A-4,121,182 pour "Electrical Tuning Circuit", ou encore dans le brevet des Etats-Unis d'Amérique US-A-4,641,116 pour "Microwave Filter", ou encore dans la demande de brevet français FR-A-2 248 621 pour "Dispostif micro-ondes muni d'un résonateur demi-onde" et enfin dans la demande de brevet européen EP-A-0 071 508 pour "Filtre hyperfréquence de petites dimensions à résonateurs linéaires".Such ring resonators are described for example in the article entitled "On the Study of Microstrip Ring and Varactor-Tuned Ring Circuits" published in the journal IEEE Transactions on Microwave Theory and Techniques, vol. MIT-35, n ° 12, December 1987, pp. 1288-1294 or even in the patent of the United States of America US-A-4,121,182 for "Electrical Tuning Circuit", or also in the patent of the United States of America US-A-4,641,116 for "Microwave Filter", or in the French patent application FR-A-2 248 621 for "Microwave device provided with a half-wave resonator" and finally in the European patent application EP-A-0 071 508 for "Microwave filter of small dimensions with linear resonators ".
Dans cet art antérieur la forme du ruban est limitée à quelques formes simples aptes à conduire à une forte surtension. On trouve donc en pratique toujours des anneaux circulaires ou éventuellement des U. Par ailleurs, dans cet art antérieur, la dimension du circuit est, par essence, de l'ordre de la longueur d'onde. Dès que la fréquence devient basse, les dimensions du résonateur deviennent prohibitives. Par exemple, à 30 MHz un résonateur de l'art antérieur constitué par un ruban circulaire aura un diamètre de 1,60 m.In this prior art, the shape of the ribbon is limited to a few simple shapes capable of leading to a high overvoltage. There are therefore in practice always circular rings or possibly U. In addition, in this prior art, the dimension of the circuit is, in essence, of the order of the wavelength. As soon as the frequency becomes low, the dimensions of the resonator become prohibitive. For example, at 30 MHz a resonator of the prior art constituted by a circular ribbon will have a diameter of 1.60 m.
La présente invention a justement pour but de remédier à ces inconvénients. A cette fin elle préconise un circuit résonnant utilisant encore un ruban conducteur mais dans des conditions de fonctionnement très différentes de celles de l'art antérieur. Dans l'invention, le ruban joue le rôle d'inductance pure dans la bande d'utilisation du circuit. Pour ce faire, sa longueur est prise inférieure à λ/8, si λ est la longueur d'onde associée à la fréquence de travail du résonateur.The object of the present invention is precisely to remedy these drawbacks. To this end, it recommends a resonant circuit still using a conductive tape but under very different operating conditions from those of the prior art. In the invention, the ribbon plays the role of pure inductance in the band of use of the circuit. To do this, its length is taken less than λ / 8, if λ is the wavelength associated with the working frequency of the resonator.
Il est à noter que des boucles résonnantes comportant une boucle microruban interrompue de longueur λ/8 et un condensateur dans l'ouverture sont déjà connues de l'art antérieur, voir par exemple le document "1986 IEEE-MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, Baltimore, Maryland, 2-4 juin 1986, pages 411-414, IEEE, New York, US; M. MAKIMOTO et al.: 'Varactor tuned bandpass filters using microstrip-line ring resonators'".It should be noted that resonant loops comprising an interrupted microstrip loop of length λ / 8 and a capacitor in the opening are already known from the prior art, see for example the document "1986 IEEE-MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST , Baltimore, Maryland, June 2-4, 1986, pages 411-414, IEEE, New York, US; M. MAKIMOTO et al .: 'Varactor tuned bandpass filters using microstrip-line ring resonators' ".
Le fait que le ruban soit un simple élément inductif entraîne que sa forme n'est en rien critique. Il est donc possible de retenir toute forme désirée, en particulier des formes qui permettent un repliement du ruban pour obtenir un gain de place.The fact that the ribbon is a simple inductive element means that its shape is in no way critical. It is therefore possible to retain any desired shape, in particular shapes that allow the ribbon to be folded up to save space.
Par ailleurs, la limitation de la longueur du ruban en-dessous de λ/8, a pour effet de diminuer l'encombrement du circuit. Combinée à la faculté de repliement, cette disposition permet d'obtenir des circuits de très faibles dimensions. Ainsi, pour reprendre l'exemple d'un circuit résonnant à 30 MHz, l'invention permet de construire un circuit de 15×2 centimètres, à comparer à l'anneau de 1,60 m de diamètre de l'art antérieur : la réduction dans les dimensions est donc d'un facteur 10.Furthermore, limiting the length of the ribbon below λ / 8 has the effect of reducing the size of the circuit. Combined with the folding ability, this arrangement makes it possible to obtain circuits of very small dimensions. So, to use the example of a 30 MHz resonant circuit, the invention makes it possible to build a 15 × 2 cm circuit, compared to the 1.60 m diameter ring of the prior art: the reduction in dimensions is therefore by a factor of 10.
Si cette réduction est particulièrement appréciable lorsque la fréquence est basse, puisqu'elle permet d'éviter des filtres d'encombrement prohibitif, elle n'est pas négligeable pour autant lorsque la fréquence est élevée, car alors le filtre présente alors des dimensions tellement faibles qu'une intégration devient possible.If this reduction is particularly appreciable when the frequency is low, since it makes it possible to avoid filters of prohibitive size, it is not negligible however when the frequency is high, because then the filter then has such small dimensions that integration becomes possible.
La présente invention a pour objet un filtre comprenant plusieurs circuits résonnants tels qu'ils ont été définis plus haut. Ces circuits (identiques ou différents) sont couplés les uns aux autres. Le couplage est serré, critique ou lâche selon le cas. Comme la forme du ruban n'est pas critique, ainsi qu'il a été souligné plus haut, on a toute latitude pour choisir la forme la mieux appropriée au couplage choisi.The subject of the present invention is a filter comprising several resonant circuits as defined above. These circuits (identical or different) are coupled to each other. The coupling is tight, critical or loose depending on the case. As the shape of the ribbon is not critical, as has been pointed out above, we are free to choose the shape best suited to the chosen coupling.
L'invention trouve ainsi un vaste domaine d'application. Des filtres de 30 MHz à 2 ou 3 GHz peuvent être réalisés. La bande passante va de quelques fractions de pourcent à environ 10%.The invention thus finds a wide field of application. Filters from 30 MHz to 2 or 3 GHz can be produced. Bandwidth ranges from a few fractions of a percent to about 10%.
De toute façon, les caractéristiques de l'invention apparaîtront mieux à la lumière de la description qui suit. Cette description porte sur des exemples donnés à titre explicatif et non limitatif et elle se réfère à des dessins annexés sur lesquels :
- la figure 1 montre un circuit résonnant,
- la figure 2 illustre le schéma électrique équivalent du circuit résonnant,
- la figure 3 montre une variante à ruban triangulaire,
- la figure 4 illustre une variante à contour replié,
- la figure 5 montre un filtre selon l'invention dans sa totalité,
- la figure 6 donne les dimensions d'un filtre selon un exemple de réalisation,
- la figure 7 montre une caractéristique d'atténuation d'un filtre passe-bande conforme à l'invention, dans une plage allant de 1 MHz à 2000 MHz,
- la figure 8 montre l'atténuation de ce même filtre autour de la fréquence centrale, dans une bande de
largeur 100 MHz, - la figure 9 montre la caractéristique d'un filtre passe-bande selon l'invention autour de la fréquence centrale dans une bande de 40 MHz,
- la figure 10 montre une autre caractéristique (temps de groupe) d'un filtre passe-bande selon l'invention autour de la fréquence centrale, dans une bande de 100 MHZ.
- FIG. 1 shows a resonant circuit,
- FIG. 2 illustrates the equivalent electrical diagram of the resonant circuit,
- FIG. 3 shows a variant with triangular ribbon,
- FIG. 4 illustrates a variant with a folded outline,
- FIG. 5 shows a filter according to the invention in its entirety,
- FIG. 6 gives the dimensions of a filter according to an exemplary embodiment,
- Figure 7 shows an attenuation characteristic a bandpass filter according to the invention, in a range from 1 MHz to 2000 MHz,
- FIG. 8 shows the attenuation of this same filter around the central frequency, in a band of
width 100 MHz, - FIG. 9 shows the characteristic of a bandpass filter according to the invention around the central frequency in a band of 40 MHz,
- FIG. 10 shows another characteristic (group time) of a bandpass filter according to the invention around the central frequency, in a band of 100 MHZ.
Un circuit résonnant selon l'invention est représenté sur la figure 1, en vue de dessus (a), en coupe (b) et dans une variante à boîtier métallique (c). Cet élément comprend un substrat plan 10, en matériau diélectrique (par exemple en verre époxy, en téflon,...). Sur la face inférieure de ce substrat, on trouve dans la variante des figures (a) et (b), une couche conductrice 12 (en cuivre par exemple) formant plan de masse et sur la face supérieure, un microruban 14 en matériau conducteur (en cuivre par exemple). Dans la variante de la figure c, le circuit est disposé dans un boîtier métallique 20 et le plan de masse est constitué par les parois métalliques 22 inférieure et supérieure. Le microruban dessine un contour "ouvert" en ce sens qu'il entoure incomplètement une partie du plan. En d'autres termes, il présente au moins une ouverture. Sur la figure 1, ce contour est rectangulaire et l'ouverture (unique) est référencée 16. Connecté à travers cette ouverture se trouve un condensateur 18 réglable ou ajusté une fois pour toutes.A resonant circuit according to the invention is shown in Figure 1, in top view (a), in section (b) and in a variant with a metal case (c). This element comprises a
Le schéma électrique équivalent est représenté sur la figure 2 en considérant encore l'élément en vue de dessus (a) et en coupe (b) dans la variante où le plan de masse est disposé sous le substrat. Sur cette figure, on voit une inductance L, due au microruban non rectiligne, un condensateur d'accord Ca connecté entre les extrémités du ruban, et des condensateurs parasites Cp, qui correspondent au volume séparant le microruban et le plan de masse.The equivalent electrical diagram is shown in FIG. 2, again considering the element in plan view (a) and in section (b) in the variant where the ground plane is arranged under the substrate. In this figure, we see an inductance L, due to the non-rectilinear microstrip, a tuning capacitor Ca connected between the ends of the ribbon, and parasitic capacitors Cp, which correspond to the volume separating the microstrip and the ground plan.
Le fonctionnement de ce résonateur est alors le suivant.The operation of this resonator is then as follows.
On désigne par l la longueur du microruban et par λ la longueur d'onde dans le substrat à la fréquence de fonctionnement. La longueur l est toujours inférieure ou égale à λ/8 pour pouvoir être assimilé à un élément de self indépendant de la fréquence.We denote by l the length of the microstrip and by λ the wavelength in the substrate at the operating frequency. The length l is always less than or equal to λ / 8 in order to be able to be assimilated to an inductor independent of the frequency.
Soit fo la fréquence centrale du filtre à réaliser ; cette fréquence est déterminée par la relation classique :Let fo be the central frequency of the filter to be produced; this frequency is determined by the classical relation:
où L est l'inductance et C la capacité équivalente du résonateur.
where L is the inductance and C the equivalent capacity of the resonator.
On commence par déterminer une valeur de L réalisable pratiquement. On détermine pour cela la longueur d'onde λo dans le substrat correspondant à fo, puis la valeur de λo/8 et on choisit une longueur de microruban inférieure à cette valeur. La valeur de l'inductance L peut être obtenue de manière approchée par la formule :We start by determining a practically achievable value of L. For this, the wavelength λo in the substrate corresponding to fo is determined, then the value of λo / 8 and a microstrip length less than this value is chosen. The value of the inductance L can be obtained approximately by the formula:
Dans cette expression :
- L est la valeur de l'inductance exprimée en Henry,
- l est la longueur du microruban, en mètre,
- Z est l'impédance de la ligne, en Ohm, et
- v est la vitesse de phase.
- L is the value of the inductance expressed in Henry,
- l is the length of the microstrip, in meters,
- Z is the line impedance, in Ohm, and
- v is the phase speed.
On a par ailleurs :We also have:
expression dans laquelle :
- c est la vitesse de phase dans le vide (soit 3.10⁸ m/s),
- ε reff est la constante diélectrique efficace du substrat, soit
expression in which:
- c is the phase velocity in a vacuum (i.e. 3.10⁸ m / s),
- ε reff is the effective dielectric constant of the substrate, is
où :
- εr est la constante diélectrique du substrat,
- h est l'épaisseur du substrat,
- W est la largeur du microruban.
or :
- εr is the dielectric constant of the substrate,
- h is the thickness of the substrate,
- W is the width of the microstrip.
La valeur Cp de la capacité parasite peut être obtenue par une formule du type :The parasitic capacitance Cp value can be obtained by a formula of the type:
où H désigne un coefficient, fonction de la géométrie du circuit.
where H indicates a coefficient, function of the geometry of the circuit.
La valeur de la capacité d'accord Ca à placer entre les deux extrémités du ruban se déduit de la formule (1), sachant que :The value of the tuning capacity Ca to be placed between the two ends of the ribbon is deduced from formula (1), knowing that:
Ainsi, se trouvent définis les paramètres du circuit résonnant. La longueur du microruban couplé et le degré de couplage sont déterminés expérimentalement.Thus, the parameters of the resonant circuit are defined. The length of the coupled microstrip and the degree of coupling are determined experimentally.
Quand la fréquence fo croît, la valeur et les dimensions des éléments L et C décroissent et l'on se heurte à une limite dans la réalisation pratique du filtre. Mais cette limite peut être dépassée si l'on répartit la capacité le long du microruban.When the frequency fo increases, the value and the dimensions of the elements L and C decrease and one encounters a limit in the practical realization of the filter. However, this limit can be exceeded if the capacity is distributed along the microstrip.
Sur la figure 3, par exemple, on voit que le contour (qui est triangulaire) dessiné par le microruban présente deux ouvertures 16, 16′(au lieu d'une seule). Chacune peut être pourvue d'un condensateur réglable 18, 18′. Chaque condensateur peut alors avoir une capacité de 2 Ca.In Figure 3, for example, we see that the outline (which is triangular) drawn by the microstrip has two
Naturellement, on pourraît utiliser plus de deux condensateurs, le cas échéant.Of course, more than two capacitors could be used, if necessary.
Pour repousser encore ces limites, on peut utiliser un substrat ayant une faible constante diélectrique (les relations 2-3 et 4 montrent en effet que si εr diminue εreff diminue, v augmente et L diminue pour une longueur l donnée).To further push these limits, we can use a substrate with a low dielectric constant (relations 2-3 and 4 show indeed that if εr decreases εreff decreases, v increases and L decreases for a given length l).
Inversement, quand la fréquence fo décroît, la valeur et les dimensions des éléments L et C croissent et l'on atteint une autre limite à la réalisation pratique du filtre. Pour la franchir, il est possible de réduire les dimensions de la cellule en repliant le microruban comme illustré sur la figure 4. Mais cette solution réduit la longueur de couplage avec la cellule suivante.Conversely, when the frequency fo decreases, the value and the dimensions of the elements L and C increase and another limit is reached in the practical realization of the filter. To cross it, it is possible to reduce the dimensions of the cell by folding up the microstrip as illustrated in FIG. 4. But this solution reduces the length of coupling with the next cell.
La figure 5 montre un filtre complet composé de cinq circuits C1 à C5 sur un substrat unique 10 avec une microbande d'entrée E et une microbande de sortie S.FIG. 5 shows a complete filter composed of five circuits C1 to C5 on a
On notera également que le filtre de l'invention utilise en entrée et en sortie un couplage direct qui réalise l'adaptation entre le premier et le dernier résonateurs et les circuits d'utilisation.It will also be noted that the filter of the invention uses a direct coupling at the input and output which performs the adaptation between the first and the last resonators and the circuits of use.
Dans le cas illustré sur la figure 5, les contours dessinés par le microruban sont rectangulaires, deux contours adjacents ayant deux côtés parallèles. Mais on pourrait utiliser aussi des circuits triangulaires par exemple montés tête-bêche.In the case illustrated in FIG. 5, the contours drawn by the microstrip are rectangular, two adjacent contours having two parallel sides. But one could also use triangular circuits for example mounted head to tail.
Dans une autre variante on peut imbriquer les circuits les uns dans les autres.In another variant, the circuits can be nested one inside the other.
La figure 6 donne les principales dimensions d'un exemple de filtre conçu pour présenter une fréquence centrale fo égale à 1131,620 MHz. Les dimensions sont en millimètres. Les condensateurs sont réglables de 0,5 à 5 pF. Le substrat est en verre époxy de 16/10 de mm d'épaisseur.Figure 6 gives the main dimensions of an example filter designed to have a center frequency fo equal to 1131.620 MHz. Dimensions are in millimeters. The capacitors are adjustable from 0.5 to 5 pF. The substrate is made of 16/10 mm thick epoxy glass.
Dans cet exemple de réalisation, les contours dessinés par les microrubans sont en forme de U, c'est-à-dire de rectangles auxquels il manque un côté. L'orientation de ces U alterne d'un résonateur à l'autre, de sorte que les condensateurs sont placés des deux côtés du filtre, tantôt en haut, tantôt en bas (au sens de la figure 6).In this exemplary embodiment, the contours drawn by the microstrips are U-shaped, that is to say rectangles with one side missing. The orientation of these U alternates from one resonator to another, so that the capacitors are placed on both sides of the filter, sometimes at the top, sometimes at the bottom (in the sense of figure 6).
Les figures 7, 8 et 9 montrent la caractéristique d'atténuation d'un filtre obtenu selon l'invention, avec des échelles de fréquence (en abscisses) différentes. Sur la figure 7, la courbe va de 1 à 2000 MHz ; sur la figure 8, la largeur de la bande de mesure est de 100 MHz ; sur la figure 9, elle est de 40 MHz.Figures 7, 8 and 9 show the attenuation characteristic of a filter obtained according to the invention, with different frequency scales (on the abscissa). In FIG. 7, the curve goes from 1 to 2000 MHz; in FIG. 8, the width of the measurement band is 100 MHz; in Figure 9, it is 40 MHz.
La courbe de la figure 10 représente la caractéristique de temps de groupe du filtre en nanoseconde par division.The curve in FIG. 10 represents the group time characteristic of the filter in nanoseconds by division.
Naturellement, si la description qui précède met l'accent sur des contours rectangulaires ce n'est qu'à titre explicatif. Toute autre forme est possible : triangulaire, circulaire, elliptique, en losange, etc.Naturally, if the foregoing description emphasizes rectangular contours, this is only for explanatory purposes. Any other shape is possible: triangular, circular, elliptical, diamond, etc.
Claims (3)
- A filter with flat resonators, comprised of at least two coupled resonators, each resonator comprising:- a conductor (12) forming an earthing plane,- opposite this earthing plane, a conductor micro tape (14) disposed on one of the faces of a dielectric substrate, this micro tape defining a contour having a first side interrupted by an opening (16), a second and a third side which are uninterrupted and are adjacent to the first side, and possibly a fourth side facing the first side, the length of the micro tape being less than λ/8, where λ is the wavelength associated with the resonance frequency of the resonator,- a capacitor (18) connected across the opening (16) interrupting the first side,this filter being characterised in that:a) it comprises more than two coupled resonators disposed in cascade (C1, C2, C3, C4, C5),b) the coupled resonators are disposed such that the second and third uninterrupted sides of two adjacent resonators are placed side by side, the electrical coupling between two adjacent resonators (C1, C2), (C2, C3), (C3, C4), (C4, C5) being effected by the second and third sides; the first sides of the resonators with their capacitors as well as the possible fourth sides being disposed along the longitudinal sides of the filter alternately on one of the longitudinal sides then the other,c) the first resonator (C1) of the filter is connected to a general input by an input micro tape (E) connected directly to the micro tape of the first resonator, this input micro tape (E) producing an adaptation between the first resonator (C1) and load circuits,d) the last resonator (C5) of the filter is connected to a general output by an output micro tape (S) connected directly to the micro tape of the last resonator, this output micro tape (S) producing an adaptation between the last resonator (5) and load circuits.
- A filter according to claim 1, characterised in that each micro tape only comprises three sides and is triangular in shape, the different triangles of the different resonators being mounted head to tail.
- A filter according to claim 1, characterised in that each micro tape comprises a folded part.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8801060 | 1988-01-29 | ||
FR8801060A FR2626716B1 (en) | 1988-01-29 | 1988-01-29 | PLANE RESONATOR FILTER |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0326498A1 EP0326498A1 (en) | 1989-08-02 |
EP0326498B1 true EP0326498B1 (en) | 1994-11-09 |
Family
ID=9362768
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890400242 Expired - Lifetime EP0326498B1 (en) | 1988-01-29 | 1989-01-27 | Resonant circuit and filter using it |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0326498B1 (en) |
DE (1) | DE68919239T2 (en) |
FR (1) | FR2626716B1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6895262B2 (en) | 1993-05-28 | 2005-05-17 | Superconductor Technologies, Inc. | High temperature superconducting spiral snake structures and methods for high Q, reduced intermodulation structures |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7231238B2 (en) | 1989-01-13 | 2007-06-12 | Superconductor Technologies, Inc. | High temperature spiral snake superconducting resonator having wider runs with higher current density |
FR2704983B1 (en) * | 1993-05-04 | 1995-06-09 | France Telecom | BANDPASS FILTER WITH SHORT-COUPLED COUPLED LINES. |
US5888942A (en) * | 1996-06-17 | 1999-03-30 | Superconductor Technologies, Inc. | Tunable microwave hairpin-comb superconductive filters for narrow-band applications |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2751558A (en) * | 1952-04-02 | 1956-06-19 | Itt | Radio frequency filter |
NL7314269A (en) * | 1973-10-17 | 1975-04-21 | Philips Nv | MICROWAVE DEVICE EQUIPPED WITH A 1/2 LAMBDA RESONATOR. |
CA1097755A (en) * | 1976-02-26 | 1981-03-17 | Mitsuo Makimoto | Electrical tuning circuit |
FR2510325B1 (en) * | 1981-07-24 | 1987-09-04 | Thomson Csf | SMALL DIMENSIONAL MICROWAVE FILTER WITH LINEAR RESONATORS |
JPS61128602A (en) * | 1984-11-28 | 1986-06-16 | Pioneer Answerphone Mfg Corp | Microwave filter |
-
1988
- 1988-01-29 FR FR8801060A patent/FR2626716B1/en not_active Expired - Lifetime
-
1989
- 1989-01-27 EP EP19890400242 patent/EP0326498B1/en not_active Expired - Lifetime
- 1989-01-27 DE DE1989619239 patent/DE68919239T2/en not_active Expired - Fee Related
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6895262B2 (en) | 1993-05-28 | 2005-05-17 | Superconductor Technologies, Inc. | High temperature superconducting spiral snake structures and methods for high Q, reduced intermodulation structures |
Also Published As
Publication number | Publication date |
---|---|
EP0326498A1 (en) | 1989-08-02 |
DE68919239T2 (en) | 1995-05-18 |
FR2626716A1 (en) | 1989-08-04 |
DE68919239D1 (en) | 1994-12-15 |
FR2626716B1 (en) | 1990-04-20 |
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