EP1550182B1 - Microwave slot-type device and slot-type antennas employing a photonic bandgap structure - Google Patents

Microwave slot-type device and slot-type antennas employing a photonic bandgap structure Download PDF

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Publication number
EP1550182B1
EP1550182B1 EP03767920A EP03767920A EP1550182B1 EP 1550182 B1 EP1550182 B1 EP 1550182B1 EP 03767920 A EP03767920 A EP 03767920A EP 03767920 A EP03767920 A EP 03767920A EP 1550182 B1 EP1550182 B1 EP 1550182B1
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European Patent Office
Prior art keywords
slot
discs
type
antenna
patterns
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EP03767920A
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German (de)
French (fr)
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EP1550182A2 (en
Inventor
Nicolas Boisbouvier
Françoise Le Bolzer
Ali Louzir
Anne-Claude Tarot
Kouroch Mahdjoubi
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THOMSON LICENSING
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Thomson Licensing SAS
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/08—Radiating ends of two-conductor microwave transmission lines, e.g. of coaxial lines, of microstrip lines
    • 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
    • H01P1/2005—Electromagnetic photonic bandgaps [EPB], or photonic bandgaps [PBG]
    • 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
    • H01P1/2016—Slot line filters; Fin line filters

Definitions

  • the present invention relates to a slot type microwave device made on a metallized substrate.
  • the present invention also relates to slit type antennas using such a structure.
  • the photonic bandgap structures known by the abbreviation BIP or generally by the term "photonic band gap structure” in the English language are periodic structures that prohibit the propagation of a wave for certain frequency bands. These structures were first used in the optical field, but in recent years their application has spread to other frequency ranges. Thus, they are used in particular in microwave devices such as antennas, filters, guides, etc.
  • the use of a photonic band gap structure with a line made using microstrip technology is described in particular in the article "Novel 2-D photonic band gap structure for microstrip lines” published in the IEEE journal “Microwave and guided wave letters - Vol. 8 - No. 2 - February 1998 » XP000730352.
  • This article describes a forbidden photonic band structure constituted by discs etched on the face of the substrate opposite to that receiving the microstrip line. This structure makes it possible to produce a filter.
  • Other examples are disclosed in WO 01/95434 and in the article of Yeo et al "Design of a Wideband Antenna Package with a compact Spatial Notch Fitter ", p. 492-495, IEEE Antennas and Propagation Symposium 2002 , XP 10591744.
  • the BIP structures are obtained mainly by engraving periodic patterns obtained by de-metallization of the ground plane of the structure produced by microstrip technology as described above, or by periodically piercing the substrate comprising the microstrip technology circuits while maintaining the continuity of the ground plane.
  • the structures already described in the prior art have great potential, including filtering.
  • the present invention therefore aims to propose the application of the production of a novel photonic bandgap structure on a microwave device in the antennas, in particular antennas of the annular slot type or Vivaldi type antennas to realize a filtering or frequency adaptation of said antenna.
  • the present invention relates to a microwave device as claimed in claim 1.
  • the periodicity between two patterns is equal to k ⁇ g / 2 where ⁇ g is the guided wavelength in the slot at the frequency of the selected forbidden band and k an odd integer.
  • the width and depth of the band gap are a function of the surface of the periodic pattern.
  • a periodic pattern has the form of a disk, which can be repeated periodically and whose area will determine the width and depth of the bandgap.
  • the periodic patterns are different patterns having the same equivalent area, namely for a disc-shaped pattern, the ratio r / a in which r is the radius and the distance between two patterns is identical while along the structure.
  • the periodic pattern is produced by etching a metal layer deposited on the face of the substrate opposite to the face receiving the slot.
  • the periodic patterns are made at least partially under the slot.
  • the present invention also relates to microwave antennas in which a BIP structure is formed to obtain a filtering of certain undesirable frequencies or to obtain several communication bands by opening forbidden bands on the frequency response of a very wide band antenna.
  • This type of antenna is particularly interesting in the field of wireless telecommunications.
  • the subject of the present invention is therefore a microwave antenna constituted by an annular slot according to claim 5.
  • the periodicity of the patterns of the BIP structure is chosen so that the frequency of the forbidden band is equal to one. harmonics of the operating frequency of the annular slot.
  • the periodicity of the patterns of the BIP structure is chosen so that the frequency of the forbidden band is greater than the operating frequency of the annular slot.
  • the structure is used in its bandwidth, which makes it possible to make the circuits using slots more compact.
  • the slot is fed in a line-slot transition by a feed line made in microstrip technology.
  • a photonic bandgap structure is formed by de-metallizing the surface of the substrate opposite the surface on which the microstrip line is made.
  • the band structure prohibited is performed along at least one of the profiles of the slot forming the antenna type Vivaldi.
  • the Vivaldi-type antenna is fed with a line-slot transition via a feed line produced using microstrip technology. It is then possible to increase the number of forbidden bands, either by adding under the microstrip line, a photonic bandgap structure by de-metallizing the surface of the substrate receiving the line, or by arranging two forbidden photonic band sizing. distinct, one on the first profile of the Vivaldi type antenna, corresponding to a first frequency band to be prohibited, and the other on the other profile of the Vivaldi type antenna, corresponding to a second band of frequency to be prohibited.
  • the device is a printed circuit provided with a line-slot. More specifically, the device comprises a substrate 1, a face 2 of which has been metallized and in which a line-slot 3 is produced by etching the metal layer 2. As shown in FIG. figure 1 the substrate has a height h, and is made of a known dielectric material.
  • the BIP structure is obtained by producing patterns 4 periodically on the face of the substrate 1 opposite the face carrying the metal layer 2.
  • the patterns 4 are made by etching a metal layer giving the metal patterns 4.
  • the patterns 4 are etched under the line-slot 3.
  • the patterns 4 are spaced a distance a which gives the repetition period of the pattern, this distance fixing the center frequency of the bandgap when the patterns are identical.
  • the distance "a" is of the order of k ⁇ g / 2 where ⁇ g is the guided wavelength in slot 3 at the central frequency of the chosen forbidden band and k an integer.
  • the pattern is of any shape. However, the equivalent area of the pattern determines the width or depth of the band gap.
  • the patterns used may be disk-shaped patterns 4a, as shown in FIG. figure 2a , rectangle or square 4b, as shown on the figure 2b , of a shape substantially in H for playing on several parameters such as the dimensions L1, L2 and g, namely a shape with 3 degrees of freedom, as represented by the pattern 4c on the Figure 2c or of annular form 4d, as shown in the figure 2d .
  • the dimensions of the pattern in particular its equivalent surface, make it possible to adjust the width or depth of the bandgap.
  • a structure according to the present invention can be obtained by using disc-shaped patterns whose radius is variable, in a progressive manner, while maintaining a spacing between disks constant and equal to a.
  • the variation can follow a defined mathematical law such as a Hamming, Barlett or Kaiser window type law.
  • the spacing between the discs can also be changed gradually.
  • the structures described above can be combined, in particular to obtain an enlargement of the band gap.
  • the center frequency corresponds to the center of the frequency band defined by the minimum frequency of the BIP structure having the lowest center frequency and the maximum frequency of the BIP structure having the highest center frequency.
  • the slit-line was simulated as being excited by two line-slot transitions 12 and 13 at each end of the slot 10.
  • the results of the simulation represented on the figure 5a allow to highlight the opening of a forbidden band having a width of about 1 GHz around the frequency 6.5 GHz.
  • a BIP structure was realized under a closed slot type antenna, fed by a feed line, more particularly a line of the microstrip line type, according to a line-slot transition using Knorr's known laws.
  • annular slot 20 is represented. This slot was made by etching a ground plane on a substrate, not shown. This annular slot 20 is fed by a microstrip line 21, the assembly being dimensioned in known manner for operation at a given frequency F0. In this case, the antenna has resonances at all the odd multiples of the frequency F0.
  • a BIP structure formed by disks 22 metallized periodically under the annular slot has been realized.
  • This BIP structure 22 is dimensioned so as to filter one of the harmonics obtained in the case of an annular slot antenna of conventional type.
  • the periodicity a between two patterns 22 has been calculated so as to have a frequency of the forbidden band corresponding, for example, to the harmonic of order 3.
  • a BIP structure of the same type can be used in its bandwidth.
  • the BIP structure is dimensioned to present a band gap at a frequency higher than the desired frequency of use.
  • the BIP structure is at the origin of an effect called "slow wave”: the phase of the transmission coefficient of a wave along a slot line is modified by the presence of the metal pellets under this line. The speed of propagation of the wave under the slot is then slowed down ("Slow-wave effect"). It is therefore possible to propose a BIP structure in which the equivalent electric length of the slot is modified.
  • the presence of the BIP structure makes it possible to reduce the guided wavelength in the slot: ⁇ boy Wut BEEP ⁇ ⁇ boy Wut ⁇ ⁇ 0
  • annular slot antenna sized at 2.4 GHz has identical operation in the presence of a BIP structure but at a lower frequency (2 GHz, for example).
  • the shape of the patterns 22a and 22b of the BIP structure may be different, for example circular or square.
  • the curve 12b if the surface of the pattern 22a and the pattern 22b is equivalent and the spacing a between two patterns is identical, substantially identical phenomena will be obtained, notably the suppression of the harmonic of rank 3 obtained with an annular slot antenna of conventional type, when the BIP structure operates as a filter.
  • the use of a BIP structure under a slot-type antenna to suppress the frequency of an odd harmonic may result in the creation of additional harmonics around the double frequency (This is represented by a low-amplitude peak around 4 GHz).
  • patterns 23 are created under the supply line 21 made in microstrip technology, by de-metallization of the ground plane below the microstrip line.
  • slots are open in the ground plane below the micro-ribbon line.
  • a Vivaldi type antenna 31 was made by opening a slot de-metallizing the surface 30, this slot having an outwardly flaring profile.
  • This Vivaldi type antenna is well known to those skilled in the art and will not be described in more detail.
  • this antenna is fed by a feed line 34 according to the Knorr principle.
  • This supply line 34 is constituted by a microstrip line.
  • a BIP structure constituted by a periodic pattern has been etched on the face of the substrate opposite the face receiving the flared slot 31, along at least one of the profiles constituting the Vivaldi type antenna.
  • the BIP structure consists of four disks 32 regularly spaced a distance a.
  • a BIP structure as represented on the figure 15 allows to create, in a Vivaldi type antenna, frequency bands in which the wave propagation is forbidden. Indeed, the Vivaldi antenna has intrinsic operation at a very wide frequency band, and the use of a BIP structure will create one or more operating subbands.
  • a Vivaldi antenna without a BIP structure has a 10 dB bandwidth of 2 GHz between 5.5 and 7.5 GHz.
  • the operating band of the Vivaldi type antenna is reduced by adding the BIP structure which prohibits the propagation of waves along the slot, between 5.5 and 7 GHz.
  • a BIP structure profile 32a, 32b, as shown in FIG. figure 17a can be used.
  • the filtering can be reinforced by supplying the Vivaldi antenna with a power supply line 34 provided with a conventional BIP 33 structure, as described above in the case of an antenna of the type with annular slot.

Abstract

The invention relates to a method of producing a photonic bandgap structure on a slot-type microwave device which is produced on a metallised substrate. According to the invention, periodically-spaced patterns (4) are formed on the surface of the aforementioned substrate (1) opposite the surface comprising the slot (3). The invention is suitable for slot-type antennas.

Description

La présente invention concerne un dispositif micro-onde de type fente réalisée sur un substrat métallisé. La présente invention concerne aussi les antennes de type fente utilisant une telle structure.The present invention relates to a slot type microwave device made on a metallized substrate. The present invention also relates to slit type antennas using such a structure.

Les structures à bandes interdites photoniques connues sous l'abréviation BIP ou de manière générale sous le terme « photonic band gap structure » en langue anglaise, sont des structures périodiques qui interdisent la propagation d'une onde pour certaines bandes de fréquences. Ces structures ont tout d'abord été utilisées dans le domaine optique mais, depuis quelques années, leur application s'est étendue à d'autres gammes de fréquences. Ainsi, on les utilise notamment dans des dispositifs micro-ondes tels que des antennes, des filtres, des guides, etc. L'utilisation d'une structure à bandes interdites photoniques avec une ligne réalisée en technologie microruban est décrite notamment dans l'article « Novel 2-D photonic band gap structure for microstrip lines » publié dans le journal IEEE « Microwave and guided wave letters - Vol. 8 - n° 2 - February 1998 » XP000730352. Cet article décrit une structure à bandes photoniques interdites constituée par des disques gravés sur la face du substrat opposée à celle recevant la ligne microruban. Cette structure permet de réaliser un filtre. D'autres exemples sont divulgués dans WO 01/95434 et dans l'article de Yeo et al "Design of a Wideband Antenna Package with a compact Spatial Notch Fitter...", P. 492-495, IEEE Antennas and Propagation Symposium 2002 , XP 10591744.The photonic bandgap structures known by the abbreviation BIP or generally by the term "photonic band gap structure" in the English language, are periodic structures that prohibit the propagation of a wave for certain frequency bands. These structures were first used in the optical field, but in recent years their application has spread to other frequency ranges. Thus, they are used in particular in microwave devices such as antennas, filters, guides, etc. The use of a photonic band gap structure with a line made using microstrip technology is described in particular in the article "Novel 2-D photonic band gap structure for microstrip lines" published in the IEEE journal "Microwave and guided wave letters - Vol. 8 - No. 2 - February 1998 » XP000730352. This article describes a forbidden photonic band structure constituted by discs etched on the face of the substrate opposite to that receiving the microstrip line. This structure makes it possible to produce a filter. Other examples are disclosed in WO 01/95434 and in the article of Yeo et al "Design of a Wideband Antenna Package with a compact Spatial Notch Fitter ...", p. 492-495, IEEE Antennas and Propagation Symposium 2002 , XP 10591744.

Dans le cas de lignes microruban ou d'antennes de type patch, les structures BIP sont obtenues principalement soit en gravant des motifs périodiques obtenus par dé-métallisation du plan de masse de la structure réalisée en technologie microruban comme décrit ci-dessus, soit en perçant périodiquement le substrat comportant les circuits en technologie microbande tout en conservant la continuité du plan de masse. Les structures déjà décrites dans l'art antérieur présentent de grandes possibilités, notamment de filtrages.In the case of microstrip lines or patch type antennas, the BIP structures are obtained mainly by engraving periodic patterns obtained by de-metallization of the ground plane of the structure produced by microstrip technology as described above, or by periodically piercing the substrate comprising the microstrip technology circuits while maintaining the continuity of the ground plane. The structures already described in the prior art have great potential, including filtering.

La présente invention a donc pour but de proposer l'application de la réalisation d'une nouvelle structure à bandes interdites photoniques sur un dispositif micro-ondes dans les antennes, notamment les antennes du type fente annulaire ou des antennes de type Vivaldi pour réaliser un filtrage ou une adaptation en fréquence de ladite antenne.The present invention therefore aims to propose the application of the production of a novel photonic bandgap structure on a microwave device in the antennas, in particular antennas of the annular slot type or Vivaldi type antennas to realize a filtering or frequency adaptation of said antenna.

Ainsi, la présente invention a pour objet un dispositif micro-onde tel que revendiqué dans la revendication 1.Thus, the present invention relates to a microwave device as claimed in claim 1.

Selon une caractéristique supplémentaire, la périodicité entre deux motifs est égale à kλg/2 où λg est la longueur d'onde guidée dans la fente à la fréquence de la bande interdite choisie et k un entier impair. D'autre part, la largeur et la profondeur de la bande interdite sont fonction de la surface du motif périodique. Ainsi, un motif périodique a la forme d'un disque, qui pourra être répétée périodiquement et dont la superficie déterminera la largeur et la profondeur de la bande interdite. Conformément à l'invention, les motifs périodiques sont des motifs différents présentant la même surface équivalente, à savoir pour un motif sous forme de disque, le ratio r/a dans lequel r est le rayon et a la distance entre deux motifs est identique tout au long de la structure.According to an additional feature, the periodicity between two patterns is equal to kλg / 2 where λg is the guided wavelength in the slot at the frequency of the selected forbidden band and k an odd integer. On the other hand, the width and depth of the band gap are a function of the surface of the periodic pattern. Thus, a periodic pattern has the form of a disk, which can be repeated periodically and whose area will determine the width and depth of the bandgap. According to the invention, the periodic patterns are different patterns having the same equivalent area, namely for a disc-shaped pattern, the ratio r / a in which r is the radius and the distance between two patterns is identical while along the structure.

Le motif périodique est réalisé par gravure d'une couche métallique déposée sur la face du substrat opposée à la face recevant la fente. Les motifs périodiques sont réalisés au moins en partie sous la fente.The periodic pattern is produced by etching a metal layer deposited on the face of the substrate opposite to the face receiving the slot. The periodic patterns are made at least partially under the slot.

D'autre part, la présente invention concerne aussi des antennes micro-ondes dans lesquelles une structure BIP est formée pour obtenir un filtrage de certaines fréquences indésirables ou pour obtenir plusieurs bandes de communication en ouvrant des bandes interdites sur la réponse en fréquence d'une antenne très large bande. Ce type d'antennes est particulièrement intéressant dans le domaine des télécommunications sans fils.On the other hand, the present invention also relates to microwave antennas in which a BIP structure is formed to obtain a filtering of certain undesirable frequencies or to obtain several communication bands by opening forbidden bands on the frequency response of a very wide band antenna. This type of antenna is particularly interesting in the field of wireless telecommunications.

La présente invention a donc pour objet une antenne micro-onde constituée par une fente annulaire selon la revendication 5. Selon un mode de réalisation, la périodicité des motifs de la structure BIP est choisie pour que la fréquence de la bande interdite soit égale à une des harmoniques de la fréquence de fonctionnement de la fente annulaire.The subject of the present invention is therefore a microwave antenna constituted by an annular slot according to claim 5. According to one embodiment, the periodicity of the patterns of the BIP structure is chosen so that the frequency of the forbidden band is equal to one. harmonics of the operating frequency of the annular slot.

Selon un autre mode de réalisation, la périodicité des motifs de la structure BIP est choisie pour que la fréquence de la bande interdite soit supérieure à la fréquence de fonctionnement de la fente annulaire. Dans ce cas, la structure est utilisée dan sa bande passante, ce qui permet de rendre plus compacte les circuits utilisant des fentes.According to another embodiment, the periodicity of the patterns of the BIP structure is chosen so that the frequency of the forbidden band is greater than the operating frequency of the annular slot. In this case, the structure is used in its bandwidth, which makes it possible to make the circuits using slots more compact.

De préférence, la fente est alimentée selon une transition ligne-fente par une ligne d'alimentation réalisée en technologie microruban.Preferably, the slot is fed in a line-slot transition by a feed line made in microstrip technology.

Selon une caractéristique supplémentaire de l'invention, sous la ligne microruban, est réalisée une structure à bandes interdites photoniques par dé-métallisation de la surface du substrat opposée à la surface sur laquelle est réalisée la ligne microruban.According to a further feature of the invention, under the microstrip line, a photonic bandgap structure is formed by de-metallizing the surface of the substrate opposite the surface on which the microstrip line is made.

Selon encore une autre caractéristique de la présente invention, celle-ci s'applique à une antenne fente de type Vivaldi selon la revendication 9. Dans ce cas, la structure à bandes interdites est réalisée le long d'au moins un des profils de la fente formant l'antenne de type Vivaldi.According to yet another characteristic of the present invention, it applies to a Vivaldi slot antenna according to claim 9. In this case, the band structure prohibited is performed along at least one of the profiles of the slot forming the antenna type Vivaldi.

De préférence, l'antenne de type Vivaldi est alimentée selon une transition ligne-fente par une ligne d'alimentation réalisée en technologie microruban. On a alors la possibilité d'augmenter le nombre de bandes interdites, soit en ajoutant sous la ligne microruban, une structure à bandes interdites photoniques par dé-métallisation de la surface du substrat recevant la ligne, soit en disposant deux dimensionnements à bandes photoniques interdites distincts, l'un sur le premier profil de l'antenne de type Vivaldi, correspondant à une première bande de fréquence à interdire, et l'autre sur l'autre profil de l'antenne de type Vivaldi, correspondant à une seconde bande de fréquence à interdire.Preferably, the Vivaldi-type antenna is fed with a line-slot transition via a feed line produced using microstrip technology. It is then possible to increase the number of forbidden bands, either by adding under the microstrip line, a photonic bandgap structure by de-metallizing the surface of the substrate receiving the line, or by arranging two forbidden photonic band sizing. distinct, one on the first profile of the Vivaldi type antenna, corresponding to a first frequency band to be prohibited, and the other on the other profile of the Vivaldi type antenna, corresponding to a second band of frequency to be prohibited.

D'autres caractéristiques et avantages de la présente invention apparaîtront à la lecture de la description de différents modes de réalisation, cette description étant faite avec référence aux dessins ci-annexés dans lesquels :

  • Figure 1 est une vue en perspective schématique d'un dispositif micro-ondes du type fente muni d'une structure.
  • Les figures 2a, 2b, 2c et 2d représentent schématiquement différentes vues en perspective d'un dispositif micro-ondes du type fente muni d'une structure à bandes interdites photoniques dans laquelle les motifs ont différentes formes.
  • Les figures 3a et 3b représentent des modes de réalisation dans lesquels la surface des motifs suit une loi particulière.
  • La figure 4 est une vue schématique d'une structure à bandes interdites photoniques utilisée pour tester un mode de réalisation de la présente invention.
  • Les figures 5a et 5b sont des courbes comparant les coefficients de réflexion et de transmission d'une transition ligne-fente munie d'une structure à bandes interdites photoniques avec une transition ligne-fente classique.
  • La figure 6 est une courbe donnant le coefficient de transmission dans le cas d'une structure à bandes interdites photoniques constituée de disques comme représenté sur la figure 4, montrant l'influence du rayon des disques sur la bande interdite.
  • La figure 7 est une courbe donnant les coefficients de transmission et de réflexion dans le cas où la structure à bandes interdites photoniques a été dimensionnée pour réduire la taille de la bande interdite.
  • La figure 8 représente schématiquement une antenne du type fente annulaire munie d'une structure à bandes interdites photoniques, selon la présente invention.
  • La figure 9 représente une courbe donnant le coefficient de réflexion de l'antenne représentée à la figure 8, par comparaison avec une antenne fente annulaire de type classique.
  • La figure 10 représente les composantes principales de rayonnement de l'antenne dans le cas d'une antenne du type fente annulaire, comparant le cas d'une antenne munie d'une structure à bandes interdites photoniques et d'une antenne de type classique.
  • Les figures 11a et 11b représentent différentes formes pour le motif de la structure à bandes interdites photoniques.
  • La figure 12 est une courbe donnant le coefficient de réflexion des antennes des figures 11a et 11b, par comparaison avec une antenne du type fente annulaire classique.
  • La figure 13 est une représentation schématique d'une antenne fente annulaire munie d'une structure BIP conforme à la présente invention et alimentée par une ligne d'alimentation de type microruban, munie d'une structure BIP de type classique.
  • La figure 14 est une courbe donnant le coefficient de réflexion en fonction de la fréquence pour les différentes antennes du type fente annulaire représentées dans la présente invention.
  • La figure 15 est une vue schématique d'une antenne du type Vivaldi munie d'une structure BIP selon un autre mode de réalisation de la présente invention.
  • La figure 16 est une courbe donnant le coefficient de réflexion en fonction de la fréquence, dans le cas de l'antenne de type Vivaldi représentée à la figure 15, par comparaison avec une antenne Vivaldi de type classique, et
  • Les figures 17a et 17b sont des représentations schématiques de deux autres modes de réalisation d'une antenne de type Vivaldi, conforme à la présente invention.
Other characteristics and advantages of the present invention will appear on reading the description of various embodiments, this description being made with reference to the attached drawings in which:
  • Figure 1 is a schematic perspective view of a slot-type microwave device provided with a structure.
  • The Figures 2a, 2b, 2c and 2d schematically represent different perspective views of a slot-type microwave device provided with a photonic band gap structure in which the patterns have different shapes.
  • The Figures 3a and 3b represent embodiments in which the surface of the patterns follows a particular law.
  • The figure 4 is a schematic view of a photonic bandgap structure used to test an embodiment of the present invention.
  • The Figures 5a and 5b are curves comparing the reflection and transmission coefficients of a line-slot transition provided with a photonic band gap structure with a classical line-slot transition.
  • The figure 6 is a curve giving the transmission coefficient in the case of a photonic bandgap structure consisting of disks as shown in FIG. figure 4 , showing the influence of the radius of the disks on the forbidden band.
  • The figure 7 is a curve giving the transmission and reflection coefficients in the case where the photonic bandgap structure has been sized to reduce the size of the forbidden band.
  • The figure 8 schematically represents an annular slot antenna provided with a photonic bandgap structure according to the present invention.
  • The figure 9 represents a curve giving the reflection coefficient of the antenna represented in FIG. figure 8 , compared with an annular slot antenna of conventional type.
  • The figure 10 represents the principal radiation components of the antenna in the case of an annular slot antenna, comparing the case of an antenna provided with a photonic bandgap structure and a conventional type antenna.
  • The Figures 11a and 11b represent different shapes for the pattern of the photonic band gap structure.
  • The figure 12 is a curve giving the reflection coefficient of the antennas Figures 11a and 11b compared to a conventional annular slot type antenna.
  • The figure 13 is a schematic representation of an annular slot antenna provided with a BIP structure according to the present invention and powered by a microstrip-type power supply line, provided with a conventional type BIP structure.
  • The figure 14 is a curve giving the reflection coefficient as a function of frequency for the different annular slot type antennas represented in the present invention.
  • The figure 15 is a schematic view of a Vivaldi type antenna provided with a BIP structure according to another embodiment of the present invention.
  • The figure 16 is a curve giving the reflection coefficient as a function of frequency, in the case of the Vivaldi type antenna represented in FIG. figure 15 compared to a conventional Vivaldi antenna, and
  • The Figures 17a and 17b are schematic representations of two other embodiments of a Vivaldi type antenna, according to the present invention.

Pour simplifier la description, dans les figures les mêmes éléments portent les mêmes références.To simplify the description, in the figures the same elements bear the same references.

On décrira tout d'abord avec référence aux figures 1 à 7, le procédé de réalisation d'une structure à bandes photoniques interdites dite structure BIP sur un dispositif micro-ondes de type fente.We will first describe with reference to Figures 1 to 7 , the method of producing a forbidden photonic band structure called BIP structure on a slot-type microwave device.

Conformément à la présente invention, le dispositif est un circuit imprimé muni d'une ligne-fente. De manière plus précise, le dispositif comporte un substrat 1, dont une face 2 a été métallisée et dans lequel une ligne-fente 3 est réalisée par gravure de la couche métallique 2. Comme représenté sur la figure 1, le substrat présente une hauteur h, et est réalisé en un matériau diélectrique connu.According to the present invention, the device is a printed circuit provided with a line-slot. More specifically, the device comprises a substrate 1, a face 2 of which has been metallized and in which a line-slot 3 is produced by etching the metal layer 2. As shown in FIG. figure 1 the substrate has a height h, and is made of a known dielectric material.

La structure BIP est obtenue en réalisant des motifs 4 de manière périodique sur la face du substrat 1 opposée à la face portant la couche métallique 2. Les motifs 4 sont réalisés par gravure d'une couche métallique donnant les motifs métalliques 4. De préférence, les motifs 4 sont gravés sous la ligne-fente 3.The BIP structure is obtained by producing patterns 4 periodically on the face of the substrate 1 opposite the face carrying the metal layer 2. The patterns 4 are made by etching a metal layer giving the metal patterns 4. Preferably, the patterns 4 are etched under the line-slot 3.

Pour obtenir la structure à bandes interdites photoniques, les motifs 4 sont espacés d'une distance a qui donne la période de répétition du motif, cette distance fixant la fréquence centrale de la bande interdite lorsque les motifs sont identiques. De ce fait, la distance « a » est de l'ordre de kλg/2 où λg est la longueur d'onde guidée dans la fente 3 à la fréquence centrale de la bande interdite choisie et k un entier.In order to obtain the photonic bandgap structure, the patterns 4 are spaced a distance a which gives the repetition period of the pattern, this distance fixing the center frequency of the bandgap when the patterns are identical. As a result, the distance "a" is of the order of kλg / 2 where λg is the guided wavelength in slot 3 at the central frequency of the chosen forbidden band and k an integer.

Comme représenté sur la figure 4, le motif est de forme quelconque. Toutefois, la surface équivalente du motif détermine la largeur ou la profondeur de la bande interdite.As shown on the figure 4 , the pattern is of any shape. However, the equivalent area of the pattern determines the width or depth of the band gap.

Comme représenté sur les figures 2a à 2d, les motifs utilisés peuvent être des motifs en forme de disque 4a, comme représenté sur la figure 2a, de rectangle ou de carré 4b, comme représenté sur la figure 2b, d'une forme sensiblement en H permettant de jouer sur plusieurs paramètres tels que les dimensions L1, L2 et g, à savoir une forme à 3 degrés de liberté, telle que représentée par le motif 4c sur la figure 2c ou de forme annulaire 4d, comme représenté sur la figure 2d. Comme cela sera démontré ci-après, les dimensions du motif, notamment sa surface équivalente, permettent d'ajuster la largeur ou la profondeur de la bande interdite.As shown on Figures 2a to 2d , the patterns used may be disk-shaped patterns 4a, as shown in FIG. figure 2a , rectangle or square 4b, as shown on the figure 2b , of a shape substantially in H for playing on several parameters such as the dimensions L1, L2 and g, namely a shape with 3 degrees of freedom, as represented by the pattern 4c on the Figure 2c or of annular form 4d, as shown in the figure 2d . As will be demonstrated below, the dimensions of the pattern, in particular its equivalent surface, make it possible to adjust the width or depth of the bandgap.

D'autre part, comme représenté sur les figures 3a et 3b, une structure conforme à la présente invention peut être obtenue en utilisant des motifs sous forme de disque dont le rayon est variable, de manière progressive, tout en maintenant un espacement entre disques constant et égal à a. La variation peut suivre une loi mathématique définie telle qu'une loi du type fenêtre de Hamming, Barlett ou Kaiser. D'autre part, comme représenté sur la figure 3b, l'espacement entre les disques peut aussi être modifié de manière progressive.On the other hand, as shown on Figures 3a and 3b a structure according to the present invention can be obtained by using disc-shaped patterns whose radius is variable, in a progressive manner, while maintaining a spacing between disks constant and equal to a. The variation can follow a defined mathematical law such as a Hamming, Barlett or Kaiser window type law. On the other hand, as represented on the figure 3b , the spacing between the discs can also be changed gradually.

De plus, les structures décrites ci-dessus peuvent être combinées, en particulier pour obtenir un élargissement de la bande interdite. Ainsi, il est possible de mettre en cascade deux structures du type représenté à la figure 4, l'une avec un espacement a et des motifs sous forme de disque de rayon r, l'autre avec un espacement a' et des motifs sous forme de disque de rayon r'. Dans ce cas, la fréquence centrale correspond au centre de la bande de fréquence définie par la fréquence minimale de la structure BIP ayant la plus basse fréquence centrale et par la fréquence maximale de la structure BIP ayant la plus haute fréquence centrale.In addition, the structures described above can be combined, in particular to obtain an enlargement of the band gap. Thus, it is possible to cascade two structures of the type represented in figure 4 , one with spacing a and patterns in the form of disc of radius r, the other with a spacing a 'and patterns in the form of disc of radius r'. In this case, the center frequency corresponds to the center of the frequency band defined by the minimum frequency of the BIP structure having the lowest center frequency and the maximum frequency of the BIP structure having the highest center frequency.

On décrira maintenant, plus particulièrement avec référence aux figures 4 à 7, l'utilisation de la structure BIP conforme à l'invention, dans des antennes de type fente, pour obtenir un filtrage de certaines fréquences, à savoir réaliser un filtre coupe-bande.We will describe now, more particularly with reference to Figures 4 to 7 , the use of the BIP structure according to the invention, in slot type antennas, to obtain a filtering of certain frequencies, namely to achieve a notch filter.

Comme représenté sur la figure 4, le phénomène de filtrage a été mis en évidence en simulant une ligne-fente 10, dans laquelle on a métallisé des disques 11, ces disques étant réalisés selon un motif périodique, avec une période a, telle que a = λg/2, λg étant défini comme ci-dessus et le disque présentant un rayon r.As shown on the figure 4 , the filtering phenomenon has been demonstrated by simulating a line-slot 10, in which we have metallized disks 11, these disks being made in a periodic pattern, with a period a, such that a = λg / 2, λg being defined as above and the disc having a radius r.

La ligne-fente a été simulée comme étant excitée par deux transitions ligne-fente 12 et 13, à chaque extrémité de la fente 10. La ligne-fente a été dimensionnée en utilisant les lois établies par Knorr et dans le cas de la présente invention, on a pris comme dimensions a = 18.9 mm, r = 2.4 mm et n = 9. Les résultats de la simulation représentés sur la figure 5a permettent de mettre en évidence l'ouverture d'une bande interdite ayant une largeur d'environ 1 GHz autour de la fréquence 6.5 GHz. Lorsque l'on compare les résultats de la figure 5a avec ceux obtenus pour une ligne-fente sans structure à bandes photoniques interdites, comme représenté sur la figure 5b, on s'aperçoit que l'on a créé un filtre coupe-bande autour de 6.5 GHz.The slit-line was simulated as being excited by two line-slot transitions 12 and 13 at each end of the slot 10. The slit-line was sized using the laws established by Knorr and in the case of the present invention , we took as dimensions a = 18.9 mm, r = 2.4 mm and n = 9. The results of the simulation represented on the figure 5a allow to highlight the opening of a forbidden band having a width of about 1 GHz around the frequency 6.5 GHz. When comparing the results of the figure 5a with those obtained for a line-slot without structure with prohibited photonic bands, as represented on the figure 5b , we see that we have created a notch filter around 6.5 GHz.

En partant de la même structure, on a simulé des disques ayant des rayons différents et l'on a obtenu les résultats représentés sur la figure 6, dans le cas d'une structure photonique à six disques avec des rayons r variant entre 2.7 mm et 4.2 mm. On s'aperçoit que la surface du disque entraîne une modification de la largeur et de la profondeur du coefficient de transmission des bandes photoniques interdites.Starting from the same structure, disks having different radii were simulated and the results shown on the diagram were obtained. figure 6 in the case of a six-disk photonic structure with r-rays varying between 2.7 mm and 4.2 mm. It can be seen that the surface of the disk causes a change in the width and the depth of the transmission coefficient of the prohibited photonic strips.

Sur la figure 7, on a représenté le coefficient de réflexion d'une structure telle que celle de la figure 4, avec des motifs BIP constitués par vingt disques de rayon 1.6 mm avec un espacement de a = 14.7 mm. Dans ce cas, on s'aperçoit que l'on a une bande interdite étroite de 700 MHz autour de la fréquence 7.5 GHz.On the figure 7 , the reflection coefficient of a structure such as that of the figure 4 , with BIP patterns consisting of twenty discs of radius 1.6 mm with a spacing of a = 14.7 mm. In this case, we realize that we have a narrow forbidden band of 700 MHz around the frequency 7.5 GHz.

Basé sur les différents résultats de simulation, il est donc possible de déterminer le dimensionnement d'une structure BIP constituée par des disques métalliques susceptibles d'avoir une bande photonique interdite centrée sur une fréquence souhaitée. Ainsi, soit a la période de répétition du motif BIP et λbi la longueur d'onde correspondant à la fréquence centrale de la bande interdite souhaitée, la période peut être obtenue en utilisant l'équation suivante : a = λ bl / 2 ⁢ √ε eff

Figure imgb0001
où εeff représente la permittivité effective du substrat.Based on the different simulation results, it is therefore possible to determine the dimensioning of a BIP structure constituted by metal disks likely to have a prohibited photon band centered on a desired frequency. Thus, either at the repetition period of the BIP pattern and λ bi the wavelength corresponding to the center frequency of the desired forbidden band, the period can be obtained by using the following equation: at = λ bl / 2 ⁢ √ε eff
Figure imgb0001
 where ε eff represents the effective permittivity of the substrate.

On s'aperçoit ensuite que le rayon r des disques influence la largeur et la profondeur du coefficient de transmission de la bande interdite. Une bande interdite significative (S21 de l'ordre de -20dB) est obtenue pour une valeur telle que 0.15 < r/a < 0.25.It is then seen that the radius r of the disks influences the width and the depth of the transmission coefficient of the band gap. A significant band gap (S21 of the order of -20dB) is obtained for a value such that 0.15 <r / a <0.25.

Cela a été démontré dans les figures données ci-dessus.This has been demonstrated in the figures given above.

On décrira maintenant avec référence aux figures 8 à 17, différentes structures d'antennes de type fente munies de structures BIP obtenues selon le procédé décrit ci-dessus, pour réaliser des fonctions de filtrage.We will now describe with reference to Figures 8 to 17 , various slot-type antenna structures provided with BIP structures obtained according to the method described above, to perform filtering functions.

Ainsi, dans le cas des figures 8 à 12, on a réalisé une structure BIP sous une antenne du type fente fermée, alimentée par une ligne d'alimentation, plus particulièrement une ligne du type ligne microruban, selon une transition ligne-fente utilisant les lois connues de Knorr.Thus, in the case of Figures 8 to 12 , a BIP structure was realized under a closed slot type antenna, fed by a feed line, more particularly a line of the microstrip line type, according to a line-slot transition using Knorr's known laws.

Sur la figure 8, on a représenté très schématiquement, une fente annulaire 20. Cette fente a été réalisée par gravure d'un plan de masse sur un substrat non représenté. Cette fente annulaire 20 est alimentée par une ligne microruban 21, l'ensemble étant dimensionné de manière connue pour un fonctionnement à une fréquence donnée F0. Dans ce cas, l'antenne présente des résonances à tous les multiples impairs de la fréquence F0.On the figure 8 schematically, an annular slot 20 is represented. This slot was made by etching a ground plane on a substrate, not shown. This annular slot 20 is fed by a microstrip line 21, the assembly being dimensioned in known manner for operation at a given frequency F0. In this case, the antenna has resonances at all the odd multiples of the frequency F0.

Conformément à la présente invention, on a réalisé une structure BIP formée par des disques 22 métallisés périodiquement sous la fente annulaire. Cette structure BIP 22 est dimensionnée de manière à filtrer une des harmoniques obtenues dans le cas d'une antenne-fente annulaire de type classique.According to the present invention, a BIP structure formed by disks 22 metallized periodically under the annular slot has been realized. This BIP structure 22 is dimensioned so as to filter one of the harmonics obtained in the case of an annular slot antenna of conventional type.

Ainsi, la périodicité a entre deux motifs 22 a été calculée de manière à avoir une fréquence de la bande interdite correspondant, par exemple, à l'harmonique d'ordre 3. A titre d'exemple, pour un fonctionnement à F0 = 2.4 GHz, le rayon de la fente annulaire 20 est R = 5.4 mm et la longueur de la ligne microruban 21 est de 20 mm.Thus, the periodicity a between two patterns 22 has been calculated so as to have a frequency of the forbidden band corresponding, for example, to the harmonic of order 3. As an example, for an operation at F0 = 2.4 GHz the radius of the annular slot 20 is R = 5.4 mm and the length of the microstrip line 21 is 20 mm.

Comme représenté sur la figure 9, on obtient des résonances parasites autour de 7 GHz, soit sensiblement à une valeur 3F0, alors que l'allure du coefficient de réflexion est sensiblement plate dans la région autour de 5 GHz. Cette antenne-fente est munie d'une structure BIP dont les dimensions ont été calculées en utilisant les règles données ci-dessus pour les disques. On obtient donc une périodicité entre disques a = 14.7 mm et un rayon des disques de 3.7 mm de manière à éliminer la fréquence de résonance autour de 7 GHz. Cela est représenté sur la figure 9 par la courbe munie de points. Avec les deux types d'antennes et comme représenté sur la figure 10, on obtient un diagramme de rayonnement omnidirectionnel sensiblement similaire. Ceci résulte aussi du tableau A ci-après donnant l'efficacité du rayonnement et l'efficacité de l'antenne pour les deux cas. TABLEAU A ASA
2.4 GHz ASA avec BIP
2.05 GHz Efficacité de rayonnement (%) 93,6 92,8 Efficacité de l'antenne (%) 93,1 86 As shown on the figure 9 parasitic resonances around 7 GHz are obtained, ie substantially at a value of 3F0, whereas the shape of the reflection coefficient is substantially flat in the region around 5 GHz. This antenna-slot is provided with a BIP structure whose dimensions have been calculated using the rules given above for the disks. We thus obtain a periodicity between discs a = 14.7 mm and a disc radius of 3.7 mm so as to eliminate the resonance frequency around 7 GHz. This is represented on the figure 9 by the curve provided with points. With both types of antennas and as represented on the figure 10 a substantially similar omnidirectional radiation pattern is obtained. This also results from Table A below giving the radiation efficiency and the efficiency of the antenna for both cases. TABLE A ASA
2.4 GHz ASA with BIP
2.05 GHz Radiation efficiency (%) 93.6 92.8 Antenna efficiency (%) 93.1 86

Selon une variante de l'invention, une structure BIP de même type peut être utilisée dans sa bande passante. Dans ce cas, la structure BIP est dimensionnée pour présenter une bande interdite à une fréquence plus élevée que la fréquence d'utilisation souhaitée. Dans sa bande passante, la structure BIP est à l'origine d'un effet appelé « slow wave » : la phase du coefficient de transmission d'une onde le long d'une ligne fente est modifiée par la présence des pastilles métalliques sous cette ligne. La vitesse de propagation de l'onde sous la fente est alors ralentie (« Slow-wave effect »). Il est donc possible de proposer une structure BIP dans laquelle la longueur électrique équivalente de la fente est modifiée. Autrement dit, la présence de la structure BIP permet de réduire la longueur d'onde guidée dans la fente : λ g BIP < λ g < λ 0

Figure imgb0002
According to a variant of the invention, a BIP structure of the same type can be used in its bandwidth. In this case, the BIP structure is dimensioned to present a band gap at a frequency higher than the desired frequency of use. In its bandwidth, the BIP structure is at the origin of an effect called "slow wave": the phase of the transmission coefficient of a wave along a slot line is modified by the presence of the metal pellets under this line. The speed of propagation of the wave under the slot is then slowed down ("Slow-wave effect"). It is therefore possible to propose a BIP structure in which the equivalent electric length of the slot is modified. In other words, the presence of the BIP structure makes it possible to reduce the guided wavelength in the slot: λ boy Wut BEEP < λ boy Wut < λ 0
Figure imgb0002

Avec (λ g ) BIP , la longueur d'onde guidée dans la fente en présence de la structure BIP, λ g la longueur d'onde guidée dans la fente et λ 0 , la longueur d'onde guidée dans le vide.With (λ g ) BIP , the guided wavelength in the slot in the presence of the BIP structure, λ g the wavelength guided in the slot and λ 0 , the guided wavelength in the vacuum.

Ainsi, une antenne fente annulaire dimensionnée à 2,4 GHz présente un fonctionnement identique en présence d'une structure BIP mais à une fréquence plus basse (2 GHz, par exemple).Thus, an annular slot antenna sized at 2.4 GHz has identical operation in the presence of a BIP structure but at a lower frequency (2 GHz, for example).

Comme représenté sur les figures 11 a et 11 b, la forme des motifs 22a et 22b de la structure BIP peut être différente, par exemple circulaire ou carrée. Toutefois, comme il résulte de la courbe 12b, si la surface du motif 22a et du motif 22b est équivalente et que l'espacement a entre deux motifs est identique, on obtiendra des phénomènes sensiblement identiques, notamment la suppression de l'harmonique de rang 3 obtenue avec une antenne à fente annulaire de type classique, lorsque la structure BIP fonctionne en filtre.As shown on figures 11 a and 11b, the shape of the patterns 22a and 22b of the BIP structure may be different, for example circular or square. However, as a result of the curve 12b, if the surface of the pattern 22a and the pattern 22b is equivalent and the spacing a between two patterns is identical, substantially identical phenomena will be obtained, notably the suppression of the harmonic of rank 3 obtained with an annular slot antenna of conventional type, when the BIP structure operates as a filter.

Comme représenté sur les courbes de la figure 9 et de la figure 12, l'utilisation d'une structure BIP sous une antenne de type fente pour supprimer la fréquence d'une harmonique impaire peut entraîner la création d'harmoniques supplémentaires autour de la fréquence double (Cela est représenté par un pic de faible amplitude autour de 4 GHz).As shown on the curves of the figure 9 and some figure 12 , the use of a BIP structure under a slot-type antenna to suppress the frequency of an odd harmonic may result in the creation of additional harmonics around the double frequency (This is represented by a low-amplitude peak around 4 GHz).

Pour supprimer ce type d'harmonique, une structure BIP classique, comme décrit dans l'article mentionné dans l'introduction, peut être utilisée. Dans ce cas, des motifs 23 sont créés sous la ligne d'alimentation 21 réalisée en technologie microruban, par dé-métallisation du plan de masse se trouvant en dessous de la ligne microruban.To remove this type of harmonic, a classical BIP structure, as described in the article mentioned in the introduction, may to be used. In this case, patterns 23 are created under the supply line 21 made in microstrip technology, by de-metallization of the ground plane below the microstrip line.

Dans ce cas, des fentes sont ouvertes dans le plan de masse sous la ligne micro-ruban.In this case, slots are open in the ground plane below the micro-ribbon line.

Les résultats obtenus avec une telle structure sont donnés par la courbe de la figure 14, qui donne une comparaison du coefficient de réflexion S11 en fonction de la fréquence pour différents types d'antennes à fente annulaire, à savoir l'antenne de référence, l'antenne munie d'une structure BIP conforme à la présente invention et l'antenne de la figure 13. Dans ce cas, on observe une diminution de l'amplitude du pic à la fréquence de 4 GHz.The results obtained with such a structure are given by the curve of the figure 14 , which gives a comparison of the reflection coefficient S11 as a function of frequency for different types of annular slot antennas, namely the reference antenna, the antenna provided with a BIP structure according to the present invention and the antenna of the figure 13 . In this case, there is a decrease in peak amplitude at the frequency of 4 GHz.

On décrira maintenant un autre mode d'utilisation d'une structure BIP dans le cas d'une antenne fente de type Vivaldi. La description sera faite avec référence aux figures 15 à 17.Another mode of use of a BIP structure will now be described in the case of a Vivaldi slot antenna. The description will be made with reference to Figures 15 to 17 .

Comme représenté sur la figure 15, sur un substrat métallisé 30, une antenne de type Vivaldi 31 a été réalisée par ouverture d'une fente en dé-métallisant la surface 30, cette fente présentant un profil s'évasant vers l'extérieur. Cette antenne de type Vivaldi est bien connue de l'homme de l'art et ne sera pas décrite plus en détail. De manière connue, cette antenne est alimentée par une ligne d'alimentation 34 selon le principe de Knorr. Cette ligne d'alimentation 34 est constituée par une ligne microruban.As shown on the figure 15 , on a metallized substrate 30, a Vivaldi type antenna 31 was made by opening a slot de-metallizing the surface 30, this slot having an outwardly flaring profile. This Vivaldi type antenna is well known to those skilled in the art and will not be described in more detail. In known manner, this antenna is fed by a feed line 34 according to the Knorr principle. This supply line 34 is constituted by a microstrip line.

Conformément à l'invention, une structure BIP constituée par un motif périodique a été gravée sur la face du substrat opposée à la face recevant la fente évasée 31, le long d'au moins un des profils constituant l'antenne de type Vivaldi. Comme représenté sur la figure 15, la structure BIP est constituée de quatre disques 32 régulièrement espacés d'une distance a.According to the invention, a BIP structure constituted by a periodic pattern has been etched on the face of the substrate opposite the face receiving the flared slot 31, along at least one of the profiles constituting the Vivaldi type antenna. As shown on the figure 15 , the BIP structure consists of four disks 32 regularly spaced a distance a.

L'utilisation d'une structure BIP telle que représentée sur la figure 15 permet de créer, dans une antenne de type Vivaldi, des bandes de fréquences dans lesquelles la propagation des ondes est interdite. En effet, l'antenne Vivaldi a un fonctionnement intrinsèque à très large bande de fréquences, et l'utilisation d'une structure BIP permettra de créer une ou plusieurs sous-bandes de fonctionnement. La structure représentée à la figure 15, a été simulée sur une antenne de type Vivaldi fonctionnant autour d'une fréquence centrale de 5.8 GHz et présentant un profil suivant un rayon R = 350 mm, une longueur L = 99 mm et une ouverture X = 30 mm. Une antenne de type Vivaldi sans structure BIP présente une bande passante à 10 dB de 2 GHz, entre 5.5 et 7.5 GHz. Si une antenne de ce type est munie d'une structure BIP calculée pour présenter une bande interdite autour de 6.5 GHz, à savoir constituée de disques de rayon r = 4.3 mm selon une période a = 17.2 mm, on obtient un coefficient de réflexion en fonction de la fréquence telle que représentée sur la figure 16. Dans ce cas, la bande de fonctionnement de l'antenne de type Vivaldi est réduite par ajout de la structure BIP qui interdit la propagation des ondes le long de la fente, entre 5.5 et 7 GHz. Si l'on souhaite interdire deux bandes de fréquence disjointes, un profil de structure BIP 32a, 32b, tel que représenté sur la figure 17a, peut être utilisé. D'autre part, le filtrage peut être renforcé en alimentant l'antenne de type Vivaldi par une ligne d'alimentation 34 munie d'une structure BIP 33 de type classique, comme décrit ci-dessus dans le cas d'une antenne du type à fente annulaire.The use of a BIP structure as represented on the figure 15 allows to create, in a Vivaldi type antenna, frequency bands in which the wave propagation is forbidden. Indeed, the Vivaldi antenna has intrinsic operation at a very wide frequency band, and the use of a BIP structure will create one or more operating subbands. The structure represented in figure 15 , was simulated on a Vivaldi type antenna operating around a central frequency of 5.8 GHz and having a profile with a radius R = 350 mm, a length L = 99 mm and an aperture X = 30 mm. A Vivaldi antenna without a BIP structure has a 10 dB bandwidth of 2 GHz between 5.5 and 7.5 GHz. If an antenna of this type is provided with a BIP structure calculated to have a bandgap around 6.5 GHz, namely consisting of discs of radius r = 4.3 mm with a period a = 17.2 mm, a reflection coefficient of frequency function as represented on the figure 16 . In this case, the operating band of the Vivaldi type antenna is reduced by adding the BIP structure which prohibits the propagation of waves along the slot, between 5.5 and 7 GHz. If it is desired to prohibit two disjoint frequency bands, a BIP structure profile 32a, 32b, as shown in FIG. figure 17a , can be used. On the other hand, the filtering can be reinforced by supplying the Vivaldi antenna with a power supply line 34 provided with a conventional BIP 33 structure, as described above in the case of an antenna of the type with annular slot.

Il est évident pour l'homme de l'art que les modes de réalisation décrits ci-dessus ont été donnés à titre d'exemples et que le dispositif micro-onde conforme à la présente invention, peut être utilisé dans d'autres types d'antennes de type fente.It is obvious to those skilled in the art that the embodiments described above have been given as examples and that the microwave device according to the present invention can be used in other types of applications. slot type antennas.

Claims (11)

  1. Slot type microwave device comprising a filtering structure, the device being constituted by a substrate (1) covered by a metal layer (2) wherein a slot (3, 10) is realized, characterized in that the filtering structure is constituted by at least a photonic bandgap structure formed of periodic metal patterns (4) constituted by discs (4a, 11) realized on the opposite side of the substrate, from that receiving the slot, the discs presenting a ratio r/a wherein r is the radius of the discs and "a" the distance between two discs, identical along the structure.
  2. Device according to claim 1, characterized in that the periodicity between two patterns is equal to kλg/2 where λg is the wavelength of the wave guided in the slot at the chosen bandgap frequency and k is an integer.
  3. Device according to either of claims 1 or 2, characterized in that it comprises at least two cascading photonic bandgap structures.
  4. Device according to claim 3, characterized in that the ratios r/a of both structures are different from one structure to the other.
  5. Annular slot type microwave antenna constituted by an annular slot (20) realized in a ground plane deposited on a substrate, characterized in that it comprises, deposited on the opposite side of the substrate from that receiving the annular slot, at least partly beneath the annular slot, a photonic bandgap structure formed of periodic metal patterns constituted of discs (22), the discs presenting a ratio r/a wherein r is the radius of the discs and "a" the distance between two discs, identical along the structure.
  6. Microwave antenna according to Claim 5, characterized in that the periodicity of the patterns of the photonic bandgap structure is chosen so that the bandgap frequency is equal to one of the harmonics of the operating frequency of the closed slot.
  7. Microwave antenna according to Claim 5, characterized in that the periodicity of the patterns of the photonic bandgap structure is chosen so that the bandgap frequency is greater than the operating frequency of the closed slot.
  8. Antenna according to any one of Claims 5 to 7, characterized in that the annular slot (20) is fed through a slot-line transition via a feed line (21) produced in microstrip technology.
  9. Vivaldi type microwave antenna constituted by a slot (31) with a profile flaring from the feed point to the exterior comprising, deposited on the opposite side of the substrate from that receiving the slot, a photonic bandgap structure formed of periodic metal patterns (32), characterized in that the metal patterns are discs (32), the discs presenting a ratio r/a wherein r is the radius of each disc and "a" the distance between the discs, identical along the structure.
  10. Antenna according to claim 9, characterized in that the discs (32) are realized beneath and along at least one of the profiles of the slot.
  11. Antenna according to claims 9 or 10, characterized in that the Vivaldi type antenna is fed at a slot-line transition via a feed line (34) produced in microstrip technology.
EP03767920A 2002-10-11 2003-10-03 Microwave slot-type device and slot-type antennas employing a photonic bandgap structure Expired - Fee Related EP1550182B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0212656 2002-10-11
FR0212656A FR2845828B1 (en) 2002-10-11 2002-10-11 METHOD FOR PRODUCING A PHOTONIC PROHIBITED BAND STRUCTURE (BIP) ON A MICROWAVE DEVICE AND SLIT-TYPE ANTENNAS USING SUCH A STRUCTURE
PCT/FR2003/050080 WO2004034502A2 (en) 2002-10-11 2003-10-03 Slot-type antennas employing a photonic bandgap structure

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EP1550182A2 EP1550182A2 (en) 2005-07-06
EP1550182B1 true EP1550182B1 (en) 2010-09-08

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ES2265243B1 (en) * 2004-11-05 2008-01-01 Universidad Publica De Navarra PERIODIC STRUCTURES OF COHERENT RADIATION OF ANTENNAS AGRUPATIONS.
CN100588030C (en) * 2005-08-31 2010-02-03 同济大学 Photon crystal microstrip line having microstrip line closed loop
CN100463289C (en) * 2006-03-24 2009-02-18 厦门大学 Plane helical microstrip antenna for 3G system mobile terminal
FR2903235B1 (en) * 2006-06-28 2009-02-13 Thomson Licensing Sas IMPROVEMENT TO SLOT-TYPE LONGITUDINAL RADIATION ANTENNAS
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BRPI0315095B1 (en) 2017-02-21
WO2004034502A3 (en) 2004-07-08
AU2003292351A1 (en) 2004-05-04
MXPA05003836A (en) 2005-06-22
KR101144681B1 (en) 2012-05-25
JP4200134B2 (en) 2008-12-24
EP1550182A2 (en) 2005-07-06
CN1703805A (en) 2005-11-30
AU2003292351A8 (en) 2004-05-04
DE60334130D1 (en) 2010-10-21
CN1703805B (en) 2011-11-23
FR2845828B1 (en) 2008-08-22
WO2004034502A2 (en) 2004-04-22
FR2845828A1 (en) 2004-04-16
US20070097005A1 (en) 2007-05-03
JP2006502640A (en) 2006-01-19

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