EP1466384B1 - Device for receiving and/or emitting electromagnetic waves with radiation diversity - Google Patents

Description

The present invention relates to a device for receiving and / or the emission of electromagnetic waves with a radiation diversity usable in the field of wireless transmissions, particularly in the case transmissions in closed or semi-enclosed environments such as networks wireless homes, gymnasiums, television studios, movie theaters show or similar but also in communication systems wireless requiring minimal footprint for the antenna system such as in mobile telephony.

In known high-speed wireless transmission systems, the signals transmitted by the transmitter reach the receiver in a plurality distinct paths. When they are combined at the receiver, the phase differences between different departments that have traveled of different lengths, give rise to an interference figure cause fainting or significant deterioration of the signal. On the other hand, the location of fading changes during time, depending on changes in the environment, such as presence of new objects or the passage of people. These fading due to multipaths can lead to degradations important in terms of both the quality of the signal received and the system performance.

To combat fainting, the most often used is a so-called spatial diversity technique. This technique consists among other things in using a pair of antennas with wide coverage such as two patch-type antennas or "patch" associated with a switch. The two antennas are spaced a length that must be greater than or equal to λ0 / 2 where λ0 is the corresponding wavelength at the frequency of operation of the antenna. With this type of antenna, can show that the probability of having both antennas simultaneously in a fainting is very weak. On the other hand, thanks to the switch, it is possible to select the branch connected to the antenna presenting the highest signal level by examining the signal received through a control circuit. However, this solution is mainly disadvantage of being relatively large because it requires a minimum spacing between the radiating antennas to ensure sufficient decorrelation of the channel responses seen through each radiating element.

Different solutions have been proposed to reduce congestion of the antenna system while ensuring diversity sufficient. Some solutions have been the subject of several requests for patents filed in the name of THOMSON multimedia Licensing S.A. consist in particular of using several slot-type antennas fed through line-slot transitions and provided with means to obtain a radiation diversity, including diodes for switching on either antenna depending on the level of the received signal.

On the other hand, in Article IEEE, Vol. 49 No. 5 of May 2001, entitled "Diversity antenna for external mounting on wireless handsets", he also has been proposed, in the field of mobile telephony, to associate a slot λ / 4 with a monopoly to realize a radiation diversity system. However, the proposed system is a three-dimensional structure relatively complex.

US-A-5,402,136 (GOTO NAOHISA ET AL) published on March 28, 1995 discloses a device for the reception and emission of electromagnetic waves comprising a monopole antenna and several antennas type notch.

The present invention therefore aims to propose a new solution for a device for reception and / or emission of waves electromagnetic radiation-rich structures having a structure extremely compact while giving radiation diagrams presenting a very good complementarity. It also allows to obtain a device for the reception and / or emission of electromagnetic waves radiation diversity with a relatively low manufacturing cost low.

Accordingly, the present invention relates to a device for the reception and / or emission of electromagnetic waves with a diversity of radiation, comprising on a common substrate, at minus a slot-type antenna constituted by a closed curve, coupled electromagnetically to a first power line and an antenna having a radiation parallel to the substrate such as a monopole, a propeller operating in transverse mode or the like, positioned inside of the slot-type antenna and connected to a second power line, said first and second supply lines being connected by via a switching means to operating means of electromagnetic waves.

The device for receiving and / or transmitting waves electromagnetic described above uses the fact that antennas type slot constituted by a closed curve, hereinafter referred to as type antennas slot as well as antennas of the monopole or propeller type operating in transversal mode show almost omni-directional radiation patterns with minima located respectively in the plane of the substrate for the slot-type antenna and along the axis of monopoly or the propeller for the other antenna. Thus, switching from one antenna to another allows to modify the response of the channel through the antenna and to benefit thus a gain of diversity.

According to preferred embodiments, the first power supply line is made using microstrip technology or coplanar technology. On the other hand, the first power supply line has a length between its end and the electromagnetic coupling point equal to kλm / 4, where k is an odd integer and λm is the guided wavelength under the power supply line. the central frequency of operation, with λm = λ0 / √εr _eff where λ0 is the wavelength in the vacuum and εr _eff the effective permittivity of the line. The second feed line is made in microstrip technology or a coaxial line. When the line is made in microstrip technology, a connection is formed at the slot-type antenna between the outer part and the inner part of the slot, this connection being constituted, for example, by a conductive insert having an equal width at about two to three times the width of the line made in microstrip technology, so as not to disturb the operation of the excitatory microstrip line. In addition, in order to minimize the disturbance in the slot of the slot-type antenna, because of the presence of the conductive connection, this connection is made in an electric short-circuit plane for the slot which is therefore the plane of the slot. crossing the excitatory microstrip line of the monopole type antenna or helix and slot type antenna.

According to preferred embodiments, the antenna type slot is constituted by an annular slot of circular or constituted form by a closed perimeter curve equal to k'λs where k 'is an integer and λs la wavelength in the slot at the operating frequency and or by a polygonal slot such as square or rectangular. According to another characteristic of the present invention, the device for receiving and / or the emission of electromagnetic waves with a diversity of radiation can have several slot antennas nested within each other to widen the operating band or to allow multiband applications.

• la figure 1 est une vue en perspective schématique d'un premier mode de réalisation de la présente invention,
• les figures 2 et 3 sont respectivement une vue en coupe et de dessus du premier mode de réalisation,
• les figures 4 et 5 représentent en perspective le diagramme de rayonnement du monopole et le diagramme de rayonnement de la fente pour un dispositif selon les figures 1 à 3,
• la figure 6 représente une courbe donnant les paramètres S en dB en fonction de la fréquence entre les différents « ports » pour un dispositif selon les figures 1 à 3,
• la figure 7 est une vue en coupe d'un deuxième mode de réalisation de la présente invention,
• la figure 8 est une courbe identique à celle de la figure 6 pour le deuxième mode de réalisation,
• les figures 9 et 10 représentent les diagrammes de rayonnement de la fente et du monopole pour un dispositif selon la figure 7.

Other features and advantages of the present invention will appear on reading the description of various embodiments made with reference to the accompanying drawings in which:

• FIG. 1 is a schematic perspective view of a first embodiment of the present invention,
• FIGS. 2 and 3 are respectively a view in section and from above of the first embodiment,
• Figures 4 and 5 show in perspective the monopole radiation pattern and the radiation pattern of the slot for a device according to Figures 1 to 3,
• FIG. 6 represents a curve giving the parameters S in dB as a function of the frequency between the different "ports" for a device according to FIGS. 1 to 3,
• FIG. 7 is a sectional view of a second embodiment of the present invention,
• FIG. 8 is a curve identical to that of FIG. 6 for the second embodiment,
• Figures 9 and 10 show the radiation patterns of the slot and the monopole for a device according to Figure 7.

To simplify the description, in the drawings the same elements bear the same references.

As shown in FIGS. 1 to 3, the device for reception and / or emission of electromagnetic waves is constituted essentially by a slot-type antenna 1 formed of a curve closed, more particularly an annular slot, and by an antenna 2 having a radiation parallel to the plane of the slot, namely a monopoly in the embodiment shown. Monopoly 2 is positioned in the center of the annular slot 1. More specifically, as shown in FIGS. 2 and 3, the device of the present invention comprises a substrate of dielectric material 3 whose upper face has been metallized. The annular slot 1 is made by de metallizing the metal layer 4 according to a diameter circle depending on the length operating waveform of the device, more particularly the perimeter is equal to k'λs where λs is the wavelength in the slot at the frequency of functioning and k 'an integer.

On the other hand, a circular opening 5 of diameter D is provided in the center of the annular slot. This opening receives in its central part monopoly 2 which also crosses the substrate 3. Under monopoly 2 is provided, on the underside of the substrate 3, a metal annular pellet 5 of fixation. As shown more particularly in FIG. annular slot 1 is excited according to the method described by Knorr, by a microstrip line 6 connected to "port 1". This microstrip line 6 is produced on the underside of the substrate. It has between its free end 6 'and the electromagnetic coupling point with the slot 2, a length Lm = kλm / 4 where λm is the wavelength below the line and k is an odd integer.

Similarly, in the embodiment shown, monopoly 2 is excited by a microstrip line 7.

As shown in Figure 3, to ensure continuity of ground plane for the microstrip line 7 exciting the monopoly 2 it's made a connection between the inner disk and the outer ring constituting the annular slot 1. This connection is made using a conductive insert 8 of width w sufficiently wide (width equal to about 2 to 3 times the width of the excitatory printed line) not to disrupt the operation of the excitatory microstrip line. In order to to minimize the disturbance of the annular slot by the presence of this insert metal, it is made in a plane of electrical short circuit for the slot, which will be the crossover plane of the exciting line of the monopoly and annular cleft.

As shown in FIGS. 4 and 5, the annular slot 1 and the monopole 2 exhibit near-omnidirectional radiation patterns and relatively complementary to the extent that minima m are respectively located in the plane of the substrate (in the occurrence along the axis ox) for the annular slot and along the axis of the monopoly (in this case the oz axis) for the latter. So switching from one port to another (using a well-known switching device those skilled in the art, such as a switch positioned between the lines 6 and 7 and the signal processing part, driven by a signal control such as signal level, signal-to-noise ratio or similar), allows to modify the response of the channel through the antenna and thus benefit from a diversity gain. Indeed, if for example the dominant the received signal arrives along the axis ox which would be to receive a signal weak across the access connected to the slot, by switching on the connected access to the monopoly, we are likely to receive a level signal significant given that the ox direction corresponds to a maximum for the monopoly diagram. Symmetrical reasoning can be done in the case where the dominant signal arrives along the axis oz, for example in the case of multi-stage communication.

i) de la complémentarité des diagrammes de rayonnements (les directions des maxima de l'un se trouvent dans la direction des minima de l'autre)

ii) de l'orthogonalité des champs émis par la fente et le monopole.

In this case, the coupling between the annular slot 1 and the monopole 2 remains reduced, given:

i) the complementarity of the radiation patterns (the directions of the maxima of one are in the direction of the minima of the other)

ii) the orthogonality of the fields emitted by the slot and the monopoly.

Thus, one can expect minimal mutual disruption between the two radiating elements although occupying almost the same physical space.

• R_int=6.4mm (rayon intérieur de la fente)
• R_ext=6.8mm (rayon extérieur de la fente)
• W_s=0.4mm (largeur de la fente, W_s=R_ext-R_int)
• W_m1=0.3mm (largeur de la ligne microruban alimentant la fente)
• I_m1=8.25mm (longueur de la ligne microruban alimentant la fente entre le port 1 et la transition ligne/fente)
• I_m1'=8.25mm (longueur de la ligne microruban alimentant la fente entre la transition ligne/fente et l'extrémité de la ligne en circuit ouvert)
• D=2mm (diamètre de la démétallisation au centre de la fente)
• L=13.21 mm (longueur du monopole)
• □=30mm (diamètre du plan de masse)
• □_monopole=1mm (diamètre du fil métallique consituant le monopole)
• W_m2=0.2mm (largeur de la ligne microruban alimentant le monopole)
• I_m2=8.4mm (longueur de la ligne microruban alimentant le monopole entre le port 2 et la transition ligne/fente)
• Im₂'=8.8mm
• insert de 1.2mm de long (soit 3% de la longueur de la fente)
• une pastille métallique de diamètre 2mm est placée sous le monopole (elle permet de souder plus facilement le monopole à sa ligne d'alimentation)

In order to ensure the proper operation of a transmitting / receiving device as described above, it was fully sized for operation at the center frequency of about 5.8 GHz and then simulated using the Ansoft HFSS simulation software. With reference to the diagrams of FIGS. 1 to 3, the system consisting of an annular slot 1 and a monopole 2 has the following dimensions:

• R _int = 6.4mm (inner radius of the slot)
• R _ext = 6.8mm (outer radius of the slot)
• W _s = 0.4mm (width of the slot, W _s = R _ext -R _int )
• W _m1 = 0.3mm (width of the microstrip line feeding the slot)
• I _m1 = 8.25mm (length of the microstrip line feeding the slot between port 1 and the line / slot transition)
• I _m1 '= 8.25mm (length of the microstrip line feeding the slot between the line / slot transition and the end of the line in open circuit)
• D = 2mm (diameter of the demetallization at the center of the slot)
• L = 13.21 mm (length of monopoly)
• □ = 30mm (diameter of the ground plane)
• □ _monopoly = 1 mm (wire diameter consituant monopoly)
• W _m2 = 0.2mm (width of the microstrip line feeding the monopoly)
• I _m2 = 8.4mm (length of the microstrip line feeding monopoly between port 2 and line / slot transition)
• Im ₂ '= 8.8mm
• insert 1.2mm long (3% of the length of the slot)
• a 2mm diameter metal pellet is placed under the monopoly (it makes it easier to weld the monopoly to its power line)

The substrate used is Rogers 4003, with a relative permittivity □ _r = 3.38 and a thickness h = 0.81 mm.

Figure 6 shows the simulation results of the coefficients of reflection at the input of the lines feeding the annular slot (S11) and the monopoly (S22) and the coupling coefficient (S21) between the two ports 1 and 2. It can be seen a good adaptation of the 2 antennas as well as insulation between the two access better than 19dB despite the extreme proximity of the two radiating elements, namely the slot 1 and the monopole 2.

In this case, the radiation patterns obtained at the access respectively monopoly and annular slot are those represented on the Figures 4 and 5. Despite a slight distortion of the monopole diagram, it can be seen that the antenna system operates as desired, either so with quasi-omni-directional diagrams, complementary with minima along the oz axis for the monopole and the ox axis for the slot annular.

• R_int=6.4mm (rayon intérieur de la fente)
• R_ext=6.8mm (rayon extérieur de la fente)
• W_s=0.4mm (largeur de la fente, W_s=R_ext-R_int)
• W_m1=0.3mm (largeur de la ligne microruban alimentant la fente)
• I_m1=8.25mm (longueur de la ligne microruban alimentant la fente entre le port 1 et la transition ligne/fente)
• I_m1'=8.25mm (longueur de la ligne microruban alimentant la fente entre la transition ligne/fente et l'extrémité de la ligne en circuit ouvert)
• D=2mm (diamètre de la démétallisation au centre de la fente)
• L=12.4mm (longueur du monopole)
• □=30mm (diamètre du plan de masse)
• □_monopole=1mm (diamètre du fil métallique consituant le monopole)

According to a variant, represented in FIG. 7, the monopole is excited by a coaxial line connected at port 2. In this variant 2, the excitation of the monopole is on the side of the ground plane 9 of the substrate. In this case, the ground plane 9 is formed on the underside of the substrate 3. The antenna formed by the annular slot 1 is formed in this ground plane. The feed line formed of a microstrip line 6 is then formed by the upper face of the substrate, the excitation occurring as in the previous embodiment. Specific simulations of this variant were carried out using the Ansoft HFSS software, on a particular realization whose dimensioning is as follows:

• R _int = 6.4mm (inner radius of the slot)
• R _ext = 6.8mm (outer radius of the slot)
• W _s = 0.4mm (width of the slot, W _s = R _ext -R _int )
• W _m1 = 0.3mm (width of the microstrip line feeding the slot)
• I _m1 = 8.25mm (length of the microstrip line feeding the slot between port 1 and the line / slot transition)
• I _m1 '= 8.25mm (length of the microstrip line feeding the slot between the line / slot transition and the end of the line in open circuit)
• D = 2mm (diameter of the demetallization at the center of the slot)
• L = 12.4mm (length of monopoly)
• □ = 30mm (diameter of the ground plane)
• □ _monopoly = 1mm (diameter of the wire constituting the monopoly)

The substrate used is Rogers 4003, with a relative permittivity □ _r = 3.38 and a thickness h = 0.81 mm.

Adaptations to both accesses as well as insulation between two ports are shown in Figure 8. Curve S21 shows a good insulation while the S11 and S22 curves show good adaptation to the operating frequency of 5.8 GHz. Figures 9 and 10 present the radiation patterns of the device for reception and / or the emission of electromagnetic waves described above, respectively to slot and monopoly access. We can note that the coaxial line excitation of the monopoly which has the advantage of avoiding the crossing the excitation line of the monopole and the slot antenna, has better insulation (insulation greater than 22 dB) than in the case of excitation by micro-ribbon line and the monopoly diagram is more distorted. This advantage is obtained at the expense of a complexification of the antenna structure. (slot access and monopoly on opposite sides of substrate and of different types: coaxial line and microstrip line).

Other changes can be made such as the use of a propeller running on its transverse mode in place of the monopoly, the use of a double or multiple slot to expand the band or for multi-band applications, the tangential feeding of the slot to the instead of a Knorr type feed, the deformation of the annular slot to reduce even more its size, the slot can be also of square, rectangular or other polygons while remaining in the scope of the definition given above. Similarly, monopoly or propeller may be replaced by antennas of the same type which may be placed at the slot of the slot antenna and having a parallel radiation to the substrate. The power line of the slot type antenna can be made by a line in microstrip technology or in technology coplanar. In addition, the slot-type antenna can be provided with means allowing it to work in cross-polarizations, such as notches in the case of an annular slot.

Claims (11)

1. A device for receiving and/or transmitting electromagnetic waves with radiation diversity, comprising, on a common substrate (3), at least a first antenna of the slot type (1), the first antenna being electromagnetically coupled to a first supply line (6), and a second antenna radiating parallel to the substrate (2), the second antenna being positioned inside the curve forming the first antenna and being connected to a second supply line (7), said first and second supply lines being connected via a switching means to means for exploiting the electromagnetic waves, characterized in that the slot is in the form of a closed curve of perimeter equal to k'λs where λs is the wavelength in the slot at the operating frequency and k' an integer.
2. The device as claimed in claim 1, characterized in that the first supply line (6) is implemented in microstrip technology or in coplanar technology.
3. The device as claimed in claim 2, characterized in that the first supply line (6) has a length between its end and the electromagnetic coupling point equal to kλm/4, where k is an odd integer and λm the guided wavelength on the supply line at the central operating frequency with λm = λ0/√εr_eff, where λ0 is the free-space wavelength and εr_eff the effective permittivity of the line.
4. The device as claimed in any one of the preceding claims, characterized in that the second supply line (7) is implemented in microstrip technology or by a coaxial line.
5. The device as claimed in claim 4, characterized in that when the line is implemented in microstrip technology, a connection is made at the slot antenna between the part that is external and the part that is internal to the slot.
6. The device as claimed in claim 5, characterized in that the connection is formed by a conducting insert (8) having a width equal to 2 to 3 times the width of the line implemented in microstrip technology.
7. The device as claimed in either one of claims 5 and 6, characterized in that the connection is positioned in an electrical short-circuit plane for the slot.
8. The device as claimed in any one of claims 1 to 7, characterized in that the slot antenna is formed by an annular slot or a slot of polygonal shape such as a square or rectangle.
9. The device as claimed in any one of claims 1 to 8, characterized in that the antenna (2) radiating parallel to the substrate is formed by a monopole or a helix operating in transverse mode.
10. The device as claimed in claim 8, characterized in that it comprises several slot antennas interlocking one with another.
11. The device as claimed in any one of claims 1 to 10, characterized in that the antenna (2) radiating parallel to the substrate is positioned at the center of the slot antenna or antennas.

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