EP1475860A1 - Device forming antenna, sensor or electromagnetic probe - Google Patents

Abstract

The device has a module (10) with two orthogonally polarized antennas (100, 200) supported on a common support and two separated accesses connected to the respective antennas. The antenna (100) has radiating units fabricated in printed technology and synthesizing a loop. The antenna (200) has a dipole constituted of a metallic rod (210) that is surrounded by an electrical conductor.

Description

The present invention relates to the field of antennas, sensors or electromagnetic probes.

The present invention applies in particular, but not exclusively, in the field of metrology and systems of mobile telecommunications (3G, 4G).

It allows frequencies higher than GHz to be reached.

Many antenna structures and sensors or probes electromagnetic have already been proposed.

We know in particular antennas formed of structures elementary, for example in the form of a dipole, suitable for record the electric field in a linear reference polarization (either vertical or horizontal). However generally the structures of this known type presents non-isotropic diagrams.

It was also proposed to group several antennas basic to simultaneously record multiple polarizations associated with different viewing angles. Such antennas, say "Decorrelated" have complementary diagrams and polarizations.

The main object of the present invention is now to provide a device having properties superior to those of the devices known prior.

The present invention has in particular an auxiliary aim to propose a device with a maximum of decorrelated sensors. Such a goal is particularly important in the context of telecommunications mobile. Indeed the decorrelation between sensors becomes a parameter criticism which makes it possible to make the diversity of antennas to fight against fainting due to multi-path (phenomenon called "fading" of Raleigh ”). Having as many decorrelated sensors as possible in a minimum of space becomes in fact a considerable asset for increase the transmission speed thanks to a judicious treatment of signals from different sensors.

The above object is achieved in the context of the present invention by to a device comprising at least one module comprising at least two antennas with respective orthogonal polarizations between them, carried on a common support and two separate accesses connected respectively to one of the two antennas, at least one of these first antennas being formed a plurality of radiating elements produced in printed technology and synthesizing, in combination, a loop.

• la seconde antenne du module comprend un dipole constitué d'une tige métallique à excitation coaxiale,
• le dipole de la seconde antenne comprend un manchon en matériau électriquement conducteur, qui entoure la tige métallique,
• le manchon est relié à un plan de sol électriquement conducteur,
• les éléments rayonnants composant la première antenne présentent une symétrie axiale,
• la première antenne comprend un multiple de deux éléments rayonnants,
• le dispositif comprend trois modules disposés selon trois axes respectivement orthogonaux deux à deux,
• le dispositif comprend 6 capteurs constituant une antenne à 6 accès décorrélés.

According to other advantageous characteristics of the present invention:

• the second antenna of the module comprises a dipole consisting of a metal rod with coaxial excitation,
• the dipole of the second antenna comprises a sleeve of electrically conductive material, which surrounds the metal rod,
• the sleeve is connected to an electrically conductive ground plane,
• the radiating elements composing the first antenna have an axial symmetry,
• the first antenna comprises a multiple of two radiating elements,
• the device comprises three modules arranged along three axes respectively orthogonal two by two,
• the device comprises 6 sensors constituting an antenna with 6 uncorrelated accesses.

As prior documents, the applicant cites WO00 / 79649, US-4814777 and FR-2797098.

Document WO00 / 79649 describes a device for transmitting or reception of signals comprising a radiating element and a compensation adapted to compensate for the cross component of the element beaming.

The invention is distinguished at least by 3 aspects of this document.

Firstly, the invention relates to a device comprising two antennas each having their respective access. On the contrary, it is clear that according to WO00 / 79649 the compensation element is not connected to a excitation network (see page 5, line 11).

Second, nothing in WO00 / 79649 suggests a plurality of radiant elements synthesizing a loop in combination.

Third, document WO00 / 79649 relates exclusively of circular polarization while the invention uses polarizations linear, Vertical and Horizontal.

Nothing in US-4814777 suggests an antenna formed by a plurality of radiant synthesizing elements in combination, a loop.

And document FR-2797098 cannot make up for this deficiency. Fact, FR-2797098 describes an antenna comprising three plates and a plurality metallization defining two dipoles printed in orthogonal T. Those skilled in the art can in no way envisage bringing these two dipoles together since precisely, according to FR-2797098, they must remain separate.

It will also be noted that in FR-2797098, the main radiation takes place in the direction normal to the metallization plane while in the invention, the radiation takes place in the plane of metallization.

• la figure 1 représente une première vue en plan d'une plaque composant un module conforme à la présente invention,
• la figure 2 représente une seconde vue en plan, opposée à la première, d'une plaque composant un module conforme à la présente invention,
• la figure 3 représente une vue schématique en coupe axiale d'un dipole composant une antenne à polarisation verticale du module conforme à la présente invention,
• la figure 4 représente le diagramme de rayonnement en énergie de cette antenne à polarisation verticale seule dans un plan passant par l'axe de l'antenne,
• la figure 5 représente une vue schématique partielle en perspective éclatée d'une autre antenne à polarisation horizontale conforme à la présente invention réalisée en technologie imprimée,
• la figure 6 représente le diagramme de rayonnement en énergie de cette antenne à polarisation horizontale seule dans quatre plans passant par l'axe de l'antenne,
• la figure 7 représente la variation, en fonction de la fréquence, du Rapport d'Onde Stationnaire de l'antenne à polarisation verticale illustrée sur la figure 3,
• la figure 8 représente la variation, en fonction de la fréquence, du Rapport d'Onde Stationnaire de l'antenne à polarisation horizontale illustrée sur la figure 5,
• la figure 9 représente la variation, en fonction de la fréquence, de l'isolation entre ces deux antennes,
• la figure 10 représente un diagramme de rayonnement en énergie de l'antenne à polarisation horizontale,
• la figure 11 représente, dans un module conforme à la présente invention, le diagramme de rayonnement en énergie de l'antenne à polarisation horizontale dans quatre plans passant par l'axe de l'antenne, extrait de la figure 10,
• la figure 12 représente, dans un module conforme à la présente invention, le diagramme de rayonnement en énergie de la même antenne à polarisation horizontale dans un plan orthogonal à l'axe de l'antenne, extrait de la figure 10,
• la figure 13 représente un diagramme de rayonnement en énergie de l'antenne à polarisation verticale,
• la figure 14 représente, dans un module conforme à la présente invention, le diagramme de rayonnement en énergie de l'antenne à polarisation verticale dans quatre plans passant par l'axe de l'antenne, extrait de la figure 13,
• la figure 15 représente, dans un module conforme à la présente invention, le diagramme de rayonnement en énergie de la même antenne à polarisation verticale dans un plan orthogonal à l'axe de l'antenne, extrait de la figure 13, et
• la figure 16 représente une vue schématique en perspective d'une antenne conforme à un mode de réalisation préférentiel de la présente invention.

Other characteristics, aims and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of nonlimiting examples and in which:

• FIG. 1 represents a first plan view of a plate making up a module according to the present invention,
• FIG. 2 represents a second plan view, opposite the first, of a plate making up a module according to the present invention,
• FIG. 3 represents a schematic view in axial section of a dipole making up a vertically polarized antenna of the module according to the present invention,
• FIG. 4 represents the energy radiation diagram of this antenna with vertical polarization alone in a plane passing through the axis of the antenna,
• FIG. 5 represents a partial diagrammatic view in exploded perspective of another antenna with horizontal polarization according to the present invention produced in printed technology,
• FIG. 6 represents the energy radiation diagram of this antenna with horizontal polarization alone in four planes passing through the axis of the antenna,
• FIG. 7 represents the variation, as a function of frequency, of the Standing Wave Ratio of the vertical polarization antenna illustrated in FIG. 3,
• FIG. 8 represents the variation, as a function of frequency, of the Stationary Wave Ratio of the horizontally polarized antenna illustrated in FIG. 5,
• FIG. 9 represents the variation, as a function of the frequency, of the insulation between these two antennas,
• FIG. 10 represents a diagram of energy radiation from the horizontally polarized antenna,
• FIG. 11 represents, in a module in accordance with the present invention, the energy radiation diagram of the horizontally polarized antenna in four planes passing through the axis of the antenna, extracted from FIG. 10,
• FIG. 12 represents, in a module in accordance with the present invention, the energy radiation diagram of the same antenna with horizontal polarization in a plane orthogonal to the axis of the antenna, extracted from FIG. 10,
• FIG. 13 represents a diagram of energy radiation from the vertically polarized antenna,
• FIG. 14 represents, in a module in accordance with the present invention, the energy radiation diagram of the vertically polarized antenna in four planes passing through the axis of the antenna, extracted from FIG. 13,
• FIG. 15 represents, in a module in accordance with the present invention, the energy radiation diagram of the same antenna with vertical polarization in a plane orthogonal to the axis of the antenna, extracted from FIG. 13, and
• FIG. 16 represents a schematic perspective view of an antenna according to a preferred embodiment of the present invention.

As indicated previously, the device in accordance with this invention comprises at least one module 10 composed of two antennas 100, 200 having orthogonal polarizations between them.

Arbitrarily these two antennas 100 and 200 will be called horizontal polarization antenna 100 and vertical polarization antenna 200.

We will now describe the structure of the polarized antenna 100 horizontal opposite Figure 5.

This antenna 100 is inspired by the means described and illustrated in the document FR-A-2 713 020. It defines radiating elements of the type dipole produced in printed technology.

It comprises a substrate of electrically insulating material 20 which carries in the form of metallizations, on one side, a plurality of elements radiating 110 coplanar and on the other face of the supply lines 150 50 ohms respectively associated.

The substrate 20 can be formed from any suitable material. he can for example a duroid plate, having a permittivity dielectric on the order of 2.2 and a height or thickness on the order of 0.76 mm.

The radiating elements 110 are adapted to synthesize in combination of a loop centered on a Z axis perpendicular to the substrate 20. In other words, the radiating elements 110 made up of isolated segments transverse to the Z axis, correspond to the main strands a common fictitious loop centered on this axis and perpendicular to it.

The radiating elements 110 are symmetrical with respect to the axis Z.

A number of radiating elements is preferably provided 110 multiple of 2.

As can be seen in particular in FIG. 2 according to a mode of particular embodiment of the present invention, the polarization antenna horizontal 100 is formed of a metallization comprising 4 elements 130 each having the general shape of a T connected to their base at the level of a central common quadrangular block 120.

The heads or horizontal bars 132 of each of the 4 elements 130, transverse to the Z axis, are divided into two lateral strands 133, 134 (of preferably of identical length) by a central coupling slot 135 radial with respect to the Z axis. Each slot 135 preferably has a contour rectangular.

Typically the cumulative length of the two strands 133, 134, considered perpendicular to the slot 135, is of the order of magnitude of the operating wavelength.

There are thus formed 4 pairs of lateral strands 133, 134 arranged according to the sides of a square and synthesizing, as indicated previously a loop.

The foot 136 of each element 130 also extends radially with respect to the Z axis and respectively perpendicular to one of the sides from block 120.

The supply lines 150 are formed of microstrip lines by example of a width of the order of 2.35 mm. They include strands main 152 associated respectively with each pair of elements radiant 133, 134. These main strands 152 are underlying the radiating elements 133, 134 and perpendicular to the slots 135. They are used to supply the radiating elements 133, 134. The strands 152 cut the slots 135 and extend on either side thereof.

The main strands 152 which extend transversely to the Z axis are extended by auxiliary strands 154, directed towards the Z axis and substantially radial with respect to the latter.

These are themselves linked by a network of tracks 156. This is connected to a connector, for example of the SMA type, making it possible to connect the antenna 100 to a conventional coaxial cable.

The lengths and widths of the radiating strands 133, 134, of the slot 135, and supply lines 152, as well as the relative position of the strands 152 and slots 135 (ie the location of their points of secance and the length in excess respectively), will be easily adapted by those skilled in the art according to the expected characteristics of the antenna. Of course, the present invention is not limited to the mode of particular embodiment illustrated in the appended figures.

The link of the track network 156 to the aforementioned connector is referenced 160 in the appended figures.

It will be noted that this link 160 is eccentric with respect to the axis Z. This places the dipole 200 in the center of the antenna 100. The inventors have determined that this provision does not significantly disturb the antenna diagram 100 since in this area the field electric radiated by the dipoles 110 of the horizontal antenna is very low.

Preferably the supply of the antenna 100 arrives on the face of the support 20 which carries the radiating elements 110 and it passes through the support 20 to reach network 150 at point 160.

The polarization of this antenna 100 is in the plane of the dipoles 110. More precisely the direction of the electric field for each dipole 110 is illustrated under the arrow referenced DiH in FIG. 2.

The energy radiation diagram of antenna 100 is shown in Figure 6 for four planes passing through the Z axis. It is dipole and very similar to that of the antenna 200 which is illustrated on the figure 4.

We will now describe the structure of the polarization antenna 200 vertical opposite Figure 3.

This antenna 200 is inspired by the means described and illustrated in document FR-A-2 819 640.

It is formed by a dipole based on a metallic rod 210 associated to coaxial excitation.

As illustrated schematically in FIG. 3, the central rod 210, centered on the Z axis, can be surrounded by a sleeve 220 of material electrically conductive, which is electrically isolated from the rod 210. This sleeve 220 can be formed of a simple cylinder of revolution or can be layered. It facilitates the tuning of the antenna impedance.

The rod 210 and the sleeve 220 are carried by the aforementioned substrate 20. They preferably project from the face of this substrate 20 which carries the lines feed 150.

If necessary, the antenna 200 may also include a ground plane 222 of electrically conductive material, transverse to the rod 210 and to the Z axis and connected to the sleeve 220.

The direction of the electric field of such an antenna 200 is parallel to the axis of the rod 210. It is illustrated under the arrow referenced DiV in Figure 3.

The energy radiation diagram of antenna 200 is shown in Figure 4. It is characterized by a zero radiation in the direction of the axis of symmetry of the structure (which coincides with the Z axis).

Note that the radiation patterns of antenna 200 are perfectly symmetrical of revolution around the axis of the rod 210 and of the Z axis. For this reason we have illustrated a single curve in FIG. 4.

The basic module 10 illustrated in Figures 1 and 2 attached thus includes two accesses: one shown in 202 centered on the Z axis intended for the dipole of the vertical antenna 200, the other 160 offset from the to the Z axis and intended for the dipole of the horizontal antenna 100.

These two accesses allow the field to be saved simultaneously electric according to the two polarizations respectively parallel to the strands radiant 110 (called horizontal polarization) and parallel to the rod 210 (called vertical polarization) with the same type of diagram.

As illustrated in FIG. 16, three modules 10 can be placed thus constituted each comprising an antenna 100 with polarization horizontal and an antenna 200 with vertical polarization on faces adjacent and orthogonal two by two (ie non-opposite faces) of a support cube to form a three-axis probe. We thus obtain a three-dimensional probe with 6 accesses.

More precisely in this context preferably a ground plan 300 is added a few centimeters from each of the 3 substrates 20, in look at the face of these carrying the radiating elements 110.

These ground planes 300 serve as fixing means for the 3 modules 10 each comprising a horizontal antenna 100 and a vertical antenna 200. They also serve as a support for the means of connection and associated transitions required.

Figures 7 and 8 respectively represent the Wave Ratio Stationary (ROS) of a vertical antenna 200 and an antenna horizontal 100 carried on a common substrate 20 of a module, obtained successively on the two accesses of the module by closing on a load 50 ohms unmeasured access.

The ROS of the vertical antenna 200 is 1.38 at the frequency of 2012,5MHz.

The ROS of the horizontal antenna 100 is 1.13 at the frequency of 2012.5 MHz.

The insulation between the two antennas is illustrated in Figure 9. It is 35 dB at the frequency of 2012.5 MHz.

The antenna radiation energy diagram 100 to horizontal polarization is illustrated in figure 10. The directivity is 4,08dB.

Figure 11 shows the diagram in four planes passing through the Z axis, respectively for ϕ = - 45 °, ϕ = 0 °, ϕ = + 45 °, ϕ = + 90 °, with  variable from - 180 ° to + 180 °.

Figure 12 shows the diagram in the plane  = 90 °, with ϕ variable from - 180 ° to + 180 °.

These diagrams have good symmetry around the Z axis with a ripple level of 3 to 4 dB between the 0 ° and 90 ° planes and the plans at + 45 ° and - 45 °.

This phenomenon results from the synthesis of the magnetic dipole produced with 4 horizontal electric dipoles.

The energy radiation diagram of antenna 200 to vertical polarization is illustrated in Figure 13. The directivity is 2.72 dB.

Figure 14 shows the diagram in four planes passing through the Z axis, respectively for ϕ = - 45 °, ϕ = 0 °, ϕ = + 45 °, ϕ = + 90 °, with  variable from - 180 ° to + 180 °.

Figure 15 shows the diagram in the plane  = 90 °, with ϕ variable from - 180 ° to + 180 °.

As can be seen in these figures, the diagram of antenna 200 has almost perfect symmetry around the Z axis.

Of course, the present invention is not limited to the mode of particular embodiment which has just been described, but extends to all variants conform to his spirit.

The present invention provides a multi-sensor system compact with similar radiation patterns while being strongly decorrelated by polarization.

The system according to the present invention can operate in identical or different frequency bands for the vertical dipole 200 and the horizontal dipole 100, or between the different modules 10 of the probe.

Furthermore, the present invention is not limited to a system comprising 3 modules 10. By way of nonlimiting example, this invention also allows the realization of a system comprising 6 modules placed along the 6 sides of a cube, the power cables being for example arranged on a vertex or angle of the cube.

Claims (18)

Electromagnetic antenna, sensor or probe device characterized in that it comprises at least one module (10) comprising at least two antennas (100, 200) with respective polarizations orthogonal to each other, carried on a common support (20) and two accesses separate (160, 202) respectively connected to one of the two antennas (100, 200), the first one (100) at least of these antennas being formed of a plurality of radiating elements (110; 133, 134) made in printed technology and synthesizing, in combination, a loop. Device according to claim 1, characterized in that the second antenna (200) of the module comprises a dipole consisting of a metal rod (210) with coaxial excitation. Device according to claim 2, characterized in that the dipole of the second antenna (200) comprises a sleeve of electrically conductive material (220), which surrounds the metal rod (210). Device according to claim 3, characterized in that the sleeve (220) is connected to an electrically conductive ground plane (222). Device according to one of claims 1 to 4, characterized in that the radiating elements (133, 134) composing the first antenna (100) have an axial symmetry. Device according to one of claims 1 to 5, characterized in that the first antenna (100) comprises a multiple of two radiating elements (133, 134). Device according to one of claims 1 to 6, characterized in that the first antenna (100) comprises a plurality of coplanar radiating elements (133, 134) on a first face of a substrate (20) and lines d respective power supply (150) on a second face of the substrate (20). Device according to one of claims 1 to 7, characterized in that the first antenna (100) comprises a metallization comprising a multiple of 2 elements (130) having the general shape of a T connected to their base at the level of a common block (120). Device according to claim 8, characterized in that the heads (132) of each of the elements (130) are divided into two lateral strands (133, 134) by a median coupling slot (135). Device according to either of Claims 8 and 9, characterized in that it comprises supply strands (152) underlying the radiating elements (133, 134). Device according to claims 9 and 10 taken in combination, characterized in that the supply strands (152) cut the slots (135) and extend on either side thereof. Device according to one of claims 10 to 11, characterized in that the supply strands (152) are extended by auxiliary strands (154) directed towards the axis of the antenna. Device according to one of claims 1 to 12, characterized in that the feed (160) of the first antenna (100) is eccentric relative to the axis (Z) of the antenna. Device according to one of claims 1 to 13, taken in combination with claims 2 and 7, characterized in that the rod (210) projects from the face of the substrate (20) which carries the supply lines (150 ). Device according to one of claims 1 to 14, characterized in that it comprises two ports: one (202) centered for the second antenna (200), the other (160) eccentric for the first antenna (100 ). Device according to one of claims 1 to 15, characterized in that it comprises three modules (10) arranged along three axes respectively orthogonal two by two. Device according to claim 16, characterized in that it comprises a ground plane (300) underlying each module (10), which supports the connection means. Device according to one of claims 1 to 17, characterized in that it comprises 6 sensors (100, 200) constituting an antenna with 6 uncorrelated accesses.

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