WO2008055914A1

WO2008055914A1 - Multiport coupling for supplying one or more antennae from mutually independent sources antenna and antenna system comprising said coupling

Info

Publication number: WO2008055914A1
Application number: PCT/EP2007/061952
Authority: WO
Inventors: Eduardo Motta Cruz; John Bartholomew
Original assignee: Bouygues Telecom
Priority date: 2006-11-09
Filing date: 2007-11-06
Publication date: 2008-05-15
Also published as: FR2908559A1; FR2908559B1

Abstract

The invention relates to a system with one or more antennae, comprising a substrate (4) on which radiating elements (15) are arranged and an annular multiport coupling (2) to supply the radiating elements (15) from several supply sources (G1, G4), wherein the multiport coupler (2) is provided with inputs each in the form of an access port for a supply source and outlets, each in the form of a supply port for radiating elements, characterised in that the substrate (4) is supported on a ground plane (3) in which apertures (5,6) are provided facing the access ports (E/S1, E/S2) such as to give an electromagnetic coupling through the aperture between the annulus (2) and a supply source (Gl, G4) arranged with relation to the ground plane (3) such as to energise an access port on the annulus and the access ports and the supply ports are distributed around the circumference of the annulus such that the inputs are separate from each other and the outputs are separate from each other. The invention further relates to an annular multiport coupling (2).

Description

MULTI-PORT COUPLER FOR POWER SUPPLY

MULTIPLE ANTENNAS BY SOURCES ISOLATED THE UNES OF

OTHERS, ANTENNA AND ANTENNA SYSTEM INTEGRATING THE

COUPLER

The field of the invention is that of telecommunication antennas, and more particularly that of flat antennas for radio-relay systems (FH antennas).

Flat antennas now tend to be preferred over satellite dishes. Flat antennas have the advantage of being equivalent surface, globally as effective as parabolic antennas. And these flat antennas are characterized by their compactness and low weight.

A flat antenna comprises a network of radiating elements integrated in the dielectric substrate of the antenna. The flat antenna more specifically comprises a set of linear subarrays parallel to each other, each linear subarray consisting of a set of radiating elements. The radiating elements are typically each consisting of a conductive square surface having a corner connected to a subnetwork supply line (typically in the form of a microstrip line).

The power supply of the flat antenna is conventionally performed by providing the antenna with a coaxial connector, and by connecting the antenna to a waveguide via a guide-coaxial transition.

If they are not supposed to participate in the radiation, the connector elements such as straps or coaxial connectors may however be responsible for radiation parasites that could degrade the overall performance of the antenna.

On the other hand, the increase in the frequency used for radio-relay links implies the reduction of the physical dimensions of the elements of the antenna. This reduction leads to difficulties in producing the coaxial probe feed solution.

In order to respond to this problem, solutions for direct supply by waveguide have been proposed, for example (see in particular on this subject the French patent application of the Applicant filed on November 14, 2005 under No. 0511527) by implementation of electromagnetic coupling by slot between a power supply source (typically a waveguide) and the supply lines of the radiating elements of the flat antenna.

An antenna of this type, however, is associated with a single radio equipment (that is to say, a single transmission / reception chain). In other words, an antenna system has only one input.

However, it would be desirable to optimize the antennal system to share the antennal system between several radio equipment, thus combining several transmission / reception chains to one or more antennas. It is of course also sought to provide an antenna whose radiation would be as clean as possible, that is to say, absent from any parasitic component connected to the elements of connectors and derived solely from the radiating elements.

The invention aims to meet this need, and proposes for this purpose, and according to a first aspect, an antenna comprising a substrate on which are arranged radiating elements and a multiport ring coupler for supplying the radiating elements by several sources in which the multiport coupler has inputs each in the form of an access port for a power source and outputs each in the form of a radiator supply port, characterized in that the substrate rests on a ground plane in which slots are made opposite the access ports so as to achieve an electromagnetic coupling by slot between the ring and a power source arranged with respect to the ground plane to excite an access port of the ring, and in that the access ports and the power ports are distributed along the circumference of the ring so that the inputs are isolated from each other and the outputs are isolated from each other.

The electromagnetic coupling by slot between the ring and the coupler makes it possible to separate the "radiation" and "connectivity" functions of the antenna on two independent planes.

By using two opposite planes of the substrate to deposit two distinct functions (on the coupler side, the mixing functions offered by the coupler and the antennas, and on the ground plane side the slots used to transfer the signals to and from the RF equipment ), the radiation plane of the antenna is thus clear of any connection element likely to generate parasitic radiation.

This "two-plane" configuration makes it possible, for example, to have only two power supply ports on the coupler intended to feed two antennas, and to have on the rear plane two other accesses for Radio Frequency (RF) equipment that excites two access ports of the ring via two corresponding slots. The equipment (RF) - in particular transmitters and receivers - can thus be deposited directly on the rear plane of the antenna (power supply plan, for example waveguide), close to the slots that feed the coupler, with a minimum of losses.

Moreover, the distribution of the access and supply ports making it possible to ensure the independence of the antenna and power connections makes it possible to maintain the independence of the signals of different sub-networks of radiating elements, in particular to authorize, for example, the transmission and reception of several independent signals on the same plane of the antenna. The invention thus advantageously applies to any antennal solution which must have more than one access, in particular for the sharing of the spectrum or simply of a common antenna for two or more independent accesses. Some preferred, but not limiting, aspects of this antenna are:

the coupler is a microstrip ring disposed on the substrate;

the access ports are distributed along the circumference of the ring so that a wave entering an access port splits into two waves rotating in opposite directions on the ring and arriving in phase opposition to levels of other access ports;

- The power ports are distributed along the circumference of the ring so that a wave entering an access port divides into two waves rotating in opposite directions on the ring and arriving in phase at the level of the ring. each power port;

it comprises a microstrip line connected to each output port of the coupler;

the radiating elements are arranged in the form of linear sub-networks, each sub-network being connected to a sub-network supply line, and a microstrip line connected to a coupler output port serving as a supply line Subnet

the radiating elements are arranged in the form of linear sub-networks, each sub-network being connected to a sub-network supply line, and a microstrip line connected to an output port of the coupler is arranged transversely to a set linear sub-networks for supplying each of the subsystem supply lines of said set;

each of the access ports of the ring comprises a coupling pad intended to collect the energy radiated through the slot by a power source;

- the power sources are waveguides;

- A waveguide is a waveguide having a U-shaped section, arranged so that the ground plane serves as a wall closing the space of the waveguide; the power sources are microstrip lines or triplate lines.

According to a second aspect, the invention relates to an antenna system comprising a plurality of antennas according to the first aspect of the invention.

According to another aspect, the invention relates to a multiport coupler for feeding one or more antennas by at least two power sources, characterized in that it consists of a microstrip ring having inputs each in the form of an access port for a power source and one or more outputs each in the form of a radiator supply port, the access ports and the power ports being distributed along the circumference of the ring so that the inputs are isolated from each other and the outputs are isolated from each other.

Other aspects, objects and advantages of the present invention will appear better on reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and with reference to the appended drawings in which: :

- Figure 1 is a diagram showing an antenna according to the invention connected via a coupler three transmission / reception chains;

FIG. 2 represents the frequency spectrum of a FH transmission;

FIG. 3 is a diagram illustrating the transmission and reception of several different channels on the same antenna;

FIG. 4 represents the resulting spectrum at an antenna of FIG. 3;

FIGS. 5 and 6 illustrate the design of a ring coupler having five inputs;

- Figures 7, 8 and 9 show a possible embodiment of the ring coupler microstrip technology, the ring being integrated in the antenna substrate; FIG. 10 represents a possible embodiment of the supply of the radiating elements of an antenna;

FIG. 11 shows a ring coupler having a microstrip access;

- Figures 12 and 13 are diagrams showing an antenna system according to the second aspect of the invention.

With reference to the diagram of FIG. 1, there is shown an antenna A connected via a multiport coupler 1 to three transmission / reception chains C1, C2 and C3.

The coupler 1, which will be detailed in more detail later, makes it possible to develop an antenna A having several inputs (the chains C1, C2 and C3) not interfering with each other.

An illustrative and nonlimiting example of application of such an antenna is that of an antenna having two transmission / reception chains, one serving for transmission / reception of the useful signal (for example a GSM signal), and the other serving to check the conditions of reception of said useful signal (tracking chain, or "tracking" in the English terminology).

Another example of application is that of the transmission FH. In the field of radio-relay systems, duplex transmission is provided with a duplex deviation that depends on the frequency band. For radio-relay systems at 38 GHz, for example, the signals are transmitted with a duplex difference of about 1 GHz between transmission and reception. The frequency spectrum of such a transmission is shown diagrammatically in FIG. 2, in which the duplex deviation between the reception band and the emission band bears the reference Ed.

As shown schematically in FIG. 3, the multiport coupler 1 makes it possible to envisage the transmission of several different channels on the same antenna A1, and the reception of the different channels on the same antenna A2. FIG. 4 thus shows the spectrum resulting at the antenna A1 at the output of the multiport coupler 1. It will be noted that the inputs (duplex transmissions 1, 2 and 3) of the antenna do not interfere with the with each other. In particular, the reception of the channels 2 and 3 takes place in the duplex deviation separating the reception of the reception channel 3.

It is thus clear that the coupler makes it possible to multiply the bit rate of an FH link without adding an antenna, which proves particularly advantageous for meeting the integration needs of the antennas, especially in urban environments.

According to a first aspect, the invention relates to an antenna, in particular a flat antenna, comprising radiating elements (or "patch" according to the English terminology). The antenna also includes a ring multiport coupler for powering the radiating elements from multiple power sources isolated from each other.

The multiport coupler has at least two inputs each in the form of an access port for a power source, said access ports being distributed along the circumference of the ring so that a wave entering an access port divides into two waves rotating in opposite directions on the ring and arriving in phase opposition to the levels of the other access ports.

FIGS. 5 and 6 show the design of a ring multiport coupler having 5 inputs (an input that can serve as an access port for a power source). Note that in general, a coupler according to the invention can be designed to include 2n + 1 entries, with n an integer greater than or equal to 1.

Ring 2 of FIG. 5 has an electrical perimeter of 5λ / 2. We consider a reference access at the level of the arrow F.

A wave entering the ring 2 at the reference port F divides into two waves that rotate in opposite directions on the ring 2. There then exist along the circumference of the ring different remarkable places separated by a distance of λ / 4. These remarkable places correspond to:

- places where the two waves combine in phase (the path difference traveled by each of the two waves is k ^* λ, with k equal to 1 or 2 in the example here retained);

- places where the two waves combine in opposition of phase (the difference of way traveled by each of the two waves is (2p + 1) ^* λ / 2, with p equal to 0, 1 or 2 in the example here retained);

These remarkable places are marked access O and Pl for respectively:

- Access 0, corresponding to a place where the signals emitted by the reference access arrive in phase;

- Access Pl, corresponding to a place where the signals emitted by the reference access arrive in phase opposition (in theory they cancel each other mutually, in practice we find the strongly attenuated incident signal, for example 25dB).

Thus the reference access can be considered as being isolated from the accesses Pl. Similarly, if one considers an access Pl it is noted that it is also isolated from the reference access and the other accesses Pl.

As illustrated in FIG. 6, it is decided to position the I / O inputs of the coupler (that is to say the access ports for a power supply) on the locations P1. maximum of the entries relative to each other.

The coupler AA outputs (i.e. the antenna ports serving as radiator supply ports) are positioned at the locations 0 of the reference port. It will be noted that if we consider another access P1, the output AA is also positioned at a location 0 for this other access P1. Thus, at the level of an antenna access AA, the entirety (at attenuation) of signals from each of the I / O inputs.

Note also that according to the principle of reciprocity, a wave coming from the antenna, and returning to the ring 2 will recombine into phase at the I / O access level, and in phase opposition at the other AA outputs. This ensures the distribution of a signal from the antenna on the five I / O accesses, as well as the isolation of the different antenna accesses between them.

With reference to the partial perspective view of FIGS. 7, 8 and 9, the antenna is of the flat antenna type comprising a ground plane 3, and a substrate 4 attached to the ground plane on which is disposed a printed circuit containing said radiating elements.

The coupler is in the form of a ring 2, preferably made in microstrip technology, integrated in the printed circuit disposed on the substrate 4.

FIG. 7 represents an overall view illustrating the physical structure of the multiport microstrip ring coupler.

FIG. 8 more precisely represents the waveguide access subsystem, while FIG. 9 more specifically represents the microstrip access subsystem.

In the coupler of FIGS. 7, 8 and 9, two I / O access ports 1 and I / O 4 for a power source and two power supply ports AA 1 and AA 4 for radiating elements are used. In this configuration, the coupler is a quadrupole with two inputs and two outputs.

As is apparent in FIGS. 7 and 8, the substrate 4 rests on a ground plane 3 in which slots 5, 6 are formed opposite each of the I / O access ports 1 and I / O 2. On in this way performs an electromagnetic coupling by slot between the ring 2 and a power source arranged with respect to the ground plane to excite an access port of the ring.

The electromagnetic coupling by slot between the ring and the coupler makes it possible to separate the "radiation" and "connectivity" functions of the antenna on two independent planes. Two opposite planes of the substrate are actually used to deposit two distinct functions (on the coupler side, the mixing functions offered by the coupler and the antennas, and on the ground plane side the slots used to transfer signals to and from the RF equipment).

The radiation plane of the antenna is thus clear of any element of connection that may generate parasitic radiation. The equipment (RF) - in particular transmitters and receivers - can thus be deposited directly on the rear plane of the antenna, close to the slots that supply the coupler, with a minimum of losses.

Preferably, the ring 2 has, at each access port, a coupling pad 7, 8, for example circular, placed above the corresponding slot 5, 6 to harvest the energy radiated through said slot by a power source.

According to a possible embodiment, the power sources are waveguides. FIGS. 7, 8 thus represent the end of two waveguides G1, G4 each connected to an input of the coupler (ie to an I / O access port 1, I / O 4 for a power supply) .

The waveguides may be U-shaped guides in section (for example by machining a channel in a metal body), arranged relative to the ground plane so that the ground plane serves as a wall closing the waveguide space.

The waveguides may also be rectangular guides, pressed against the ground plane and in each of which a slot is made to be matched with one of the slots in the ground plane.

Furthermore, it will be noted that, preferably, a waveguide G1, G2 is terminated by short-circuiting it at a distance of λ / 4 from the slot, so as to bring an open circuit back to the slot and to maximize energy transfer from the waveguide to the microstrip line.

According to another possible embodiment (not shown), the power sources are triplet lines.

A triplate line may comprise a conductive line sandwiched between two ground planes of triplate line, and a slot of wave radiation is then practiced in one of the triplate line ground planes which is pressed against the ground plane 3 of the antenna so that one of the slits of the ground plane and the slot of the line triplate are superimposed.

Alternatively, a triplate line may comprise a conductive line sandwiched between two ground planes of triplate line, the ground plane of the antenna constituting one of the plane plane of triplate line.

According to yet another possible embodiment, the power sources are access lines in microstrip technology.

FIG. 11 schematically shows a ring multiport coupler with microstrip access. A microstrip line 9 serving as a power source is positioned transversely to a slot 5 made in the ground plane of the antenna. The ring 2 forming the coupler is integrated with the substrate attached to the ground plane. In such a way, the energy conveyed by the microstrip line 9 radiates through the slot 5 and is collected by the ring 2.

It will be noted that in this embodiment, three metallization layers are used, with a lower layer containing the microstrip access (feed plane), an intermediate layer containing the ground plane with its slot, and the upper layer containing the microstrip. coupler ring (radiation plane).

Furthermore, it will be noted that, preferably, the microstrip line 9 is terminated at a distance of λ / 4 from the slot, so as to bring an open circuit at the slot and to maximize the energy transfer of the guide. waves towards the microstrip line.

Referring now to the outputs of the coupler (radiating element supply ports such as AA1 and AA4 in FIGS. 7 and 8), and as shown in FIG. 10, it will be noted that a microstrip line 10, 11 is connected. at each output port of the coupler.

For this purpose, as is apparent in FIG. 9, the ring may have, at a remarkable location 0, a portion of microstrip line 12, 13 extending from the ring in the direction of the radius of the ring passing through this remarkable place, towards the outside of the ring to a supply port of radiating elements AA4, AA1. The ports AA4, AA1 then allow, as illustrated in Figure 9, to connect a microstrip line 10, 11 to the portion 12, 13 extending from the ring.

It will be recalled (see FIG. 10) that the radiating elements 15 of a flat antenna are typically arranged in the form of linear sub-networks, each sub-network being connected to a sub-network supply line 16.

According to a possible embodiment, shown in FIG. 10, a microstrip line 10, 11 connected to an output port AA1, AA4, of the coupler 1 is arranged transversely to a set of linear subareas for feeding each of the lines of subnet power of said set.

In another possible embodiment (not shown), a microstrip line connected to an output port of the coupler serves as a subnetwork power line.

Furthermore, it will be noted that it is also possible to connect several antennas at the output of the coupler, in particular via the microstrips lines of the type 10, 11 connected to a radiating element supply port.

The coupler described above can thus be used in antennas with several inputs and several outputs (MIMO antennas according to the English terminology "Multiple Input, Multiple Output"), allowing the reception of several independent signals on the same layer (multiple accesses). power source, for example several waveguide access) and the emission to several directions (several outputs, in particular in the form of microstrip line, supply of radiating elements.

FIG. 12 shows diagrammatically the multiport coupler 1 used in an antenna system comprising a plurality of antennas A1, A2, A3, A4, A5, each comprising radiating elements, for supplying the radiating elements of the antennas by several power sources isolated from each other (inputs E1, ..., E5).

An example of application of the antenna system of Figure 12 is shown in Figure 13, and consists in using the coupler 1 as a switch in a redundant system having two inputs E1, E2 and two antennas A1, A2.

Another example of application is that of adapting the radiation pattern of the antenna system according to the circumstances, for example in the context of mobile telephony to orient the beam of the antenna system where the radiation is located. , taking into account the movement of users within the cell covered by the antenna.

It is specified for purely illustrative and non-limiting, that an application that we will do the coupling according to the invention relates to transmissions in the band of 37.21 GHz to 38.64 GHz.

Furthermore, it will be understood that the invention is not limited to an antenna or an antenna system, but also extends to a multiport coupler as described above.

Claims

Antenna comprising a substrate (4) on which are disposed radiating elements (15) and a multiport ring coupler (2) for supplying the radiating elements by a plurality of power sources (G1, G4), wherein the multiport coupler has inputs each in the form of an access port for a power source and outputs each in the form of a radiating element supply port, characterized in that the substrate (4) rests on a ground plane (3) in which slots (5, 6) are made opposite the access ports (I / O 1, I / O 4) so as to achieve an electromagnetic coupling by slot between the ring (2) and a power source (G1, G4) arranged with respect to the ground plane (3) for exciting an access port of the ring, and in that the access ports and the ports of feeding are distributed along the circumference of the ring so that the inputs are isolated from each other and the outputs so Isolated from each other.

2. Antenna according to claim 1, characterized in that the coupler is a microstrip ring (2) disposed on the substrate.

3. Antenna according to one of claims 1 or 2, characterized in that the access ports are distributed along the circumference of the ring (2) so that a wave entering an access port is divides into two waves rotating in opposite directions on the ring and arriving in phase opposition to the levels of the other access ports.

4. Antenna according to claim 3, characterized in that the power ports are distributed along the circumference of the ring so that a wave entering an access port divides into two waves rotating in the opposite direction on the ring and arriving in phase at each power port.

5. Antenna according to claim 4, characterized in that it comprises a microstrip line (10, 11) connected to each output port (AA1, AA4) of the coupler.

Antenna according to claim 5, wherein the radiating elements (15) are arranged in the form of linear sub-networks, each sub-network being connected to a subnetwork supply line (16), characterized in that a microstrip line connected to a coupler output port serves as a subnetwork power line.

Antenna according to claim 5, wherein the radiating elements (15) are arranged in the form of linear sub-networks, each sub-network being connected to a subnetwork supply line (16), characterized in that a microstrip line (10, 11) connected to an output port of the coupler is disposed transversely to a set of linear subnets for supplying each of the subsystem supply lines of said set.

8. Antenna according to one of the preceding claims, characterized in that each of the access ports of the ring has a coupling pad (7, 8) for harvesting the energy radiated through the slot (5, 6). ) by a power source (G1, G4).

9. Antenna according to one of claims 1 to 8, characterized in that the power sources are waveguides (G1, G4).

10. Antenna according to claim 9, characterized in that a waveguide is a waveguide having a U-shaped section, arranged so that the ground plane serves as a wall closing the space of the waveguide.

11. Antenna according to one of claims 1 to 8, characterized in that the power sources are microstrip lines (9) or triplic lines.

12. Multiport coupler (1) for feeding one or more antennas by at least two power sources, characterized in that it consists of a microstrip ring (2) having inputs each in the form of an access port for a power source and one or more outputs each in the form of a radiator supply port, the access ports and the power ports being distributed on the along the circumference of the ring so that the inputs are isolated from each other and the outputs are isolated from each other.

13. Coupler according to the preceding claim, characterized in that each of the access ports comprises a coupling pad (5, 6) for harvesting the energy radiated through a slot by a power source.

Antenna system comprising a plurality of antennas (A1, .., A5), each comprising radiating elements, characterized in that it comprises a multiport ring coupler (1) according to one of claims 12 or 13 for supplying the radiating elements of the antennas by several power sources (E1, ..., E5) isolated from each other.