EP3146593A1

EP3146593A1 - Antenna system for reducing the electromagnetic coupling between antennas

Info

Publication number: EP3146593A1
Application number: EP15723030.1A
Authority: EP
Inventors: Philippe Le Thuc; Robert Staraj; Aliou Diallo; Michael Jeangeorges
Original assignee: Centre National de la Recherche Scientifique CNRS; Universite de Nice Sophia Antipolis UNSA
Current assignee: Centre National de la Recherche Scientifique CNRS; Universite de Nice Sophia Antipolis UNSA
Priority date: 2014-05-19
Filing date: 2015-05-19
Publication date: 2017-03-29
Anticipated expiration: 2035-05-19
Also published as: FR3021164B1; US10347984B2; EP3146593B1; US20170084990A1; WO2015177170A1; FR3021164A1

Abstract

The invention relates to an antenna system comprising at least two radiating elements (110, 120), a first line (130) for neutralising electromagnetic coupling between the at least two radiating elements (110, 120), at least one radiofrequency (RF) power supply line (211, 221) for each radiating element (110, 120), and at least one line (212, 222) per radiating element for short-cicuiting the antenna system (110, 120) to a ground plane (100), characterised in that the antenna system further includes: at least one second line (230, 731, 733) for neutralising electromagnetic coupling between said at least two radiating elements (110, 120), and elements (241 to 246) for activating at least some of the neutralisation lines, and in that the activation elements (241 to 246) are designed to selectively activate or deactivate at least some of the neutralisation lines (130, 230, 731, 733) such that, depending on the activation/deactivation thereof, the neutralisation lines (130, 230, 731, 733) ensure maximum neutralisation of the electromagnetic coupling of the radiating elements (110, 120) for a plurality of different frequencies.

Description

"Antenna system for reducing electromagnetic coupling between antennas" TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to the field of antennas and more particularly that of miniature antennas of the type used in all kinds of mobile electronic devices equipped with wireless communication means able to receive and transmit signals in one or more ranges of frequencies in gigahertz.

STATE OF THE ART

The rapid evolution of the electronic industry market leads to the need to design communicating wireless devices that are increasingly compact and offer more and more features. These devices almost always require multiple antennal systems that meet several needs.

On the one hand, these devices must be able to receive and transmit in the different frequency ranges corresponding to the various technologies and standards of wireless transmission that they integrate. It has become commonplace for a cellular telephone, for example: a mobile phone of the so-called GSM type, which stands for "Global System for Mobile Communications", also integrates a short-range wireless link of the "Bluetooth" type. to connect the phone to another device nearby, for example, to connect to a personal computer or mobile headset. Recent high-end mobile phones known as "smart phones" most often include a receiver for a geolocation system for satellites operating, for example with the GPS system, acronym for the English "Global Positioning System". In addition these devices are also equipped to allow their connection to a local area network wireless LAN, acronym for the English "Local Area Network". Typically, it is then a so-called Wi-Fi network obeying the group of standards known as "802.1 1" published by the North American Institute well known by the acronym "IEEE" which allows access to the Internet. Internet in all buildings and public places providing the appropriate wireless access points.

On the other hand, the addition of antennas in the same device is made necessary by the adoption, especially in Wi-Fi from standard 802.1 1 η, a more efficient mode of communication known by the acronym "MIMO" of the English "Multiple-lnput, Multiple-Output". This mode of communication favors a "diversity" of implementation of the means of transmission and / or reception for the same communication link, which typically results in the implementation of so-called spatial diversity and the simultaneous use of data. at least two reception and transmission antennas per link. This mode of transmission "in diversity" is intended in particular to take into account a particularly disturbing phenomenon, which appears very frequently in urban areas or in a confined environment of the office building type, for example, places in which Wi-Fi networks are commonly deployed. Fi. It can be seen indeed a fading of the received signal, known as "Rayleigh fading", which comes from the fact that the receiver simultaneously receives several copies out of phase through different paths of the same emitted signal. These can be added but also be subtracted up to, if not canceled, at least very strongly attenuate the received signal. The basic principle of diversity is that the receiver must be able to have at least two independent copies of the same signal and preferably the most independent possible. The probability is then low that they fade at the same time preserving a signal-to-noise ratio (SNR) sufficient for good reception of the transmitted information.

Whatever the motivations that designers of mobile communicating devices have to multiply the number of antennas within the same housing, it remains that they must remain electromagnetically independent, despite the fact that that the size of the housings that host them tends to decrease increasing their proximity, in order to be able to effectively take advantage in particular of the mode of transmission in diversity and generally to guarantee the independence of the signals received and transmitted.

Indeed, when the antennas are close to one part of the energy injected into one antenna is absorbed by the other antenna and is not radiated. This Electromagnetic coupling between antennas significantly degrades system performance.

To address this problem, as illustrated in FIG. 1, an innovative electromagnetic coupling reduction technique which manifests itself between two radiating elements, 1 10 and 120, arranged close to each other on the same support 100, by For example, a PCB printed circuit board of the English "printed circuit board", has already been described in the patent application FR2968845A1 entitled "Diversity antenna system" published on June 15, 2012. This technique improves the insulation between the accesses of the two radiating elements, 1 10 and 120, this insulation being degraded by the electromagnetic coupling which manifests itself even more between two radiating elements that they are close.

This technique consists of placing a metal line, called the neutralization line 130, between the two radiating elements, possibly different, 1 10 and 120. The radiating elements typically form antennas called PI FA, acronym for the English word "planar inverted-F". antenna ", that is," plane antenna in inverted F ". The above demand shows that a significant improvement of the isolation can then be obtained between the power ports, 1 1 1 and 121, that is to say between the input ports by which the radio signals frequency (RF) feed each of the two antennas, for a given frequency band. This innovation makes it possible to create multi-antenna systems for MIMO applications working in diversity or multistandard applications as described above. It will be noted here that, as in any PIFA antenna, the opposite portion, 1 12 and 122, of each of the power supply ports of the radiating elements, 1 1 1 and 121, is connected by a short circuit to the ground of the PCB.

Another improvement is also described in the above application which consists in using one or more active components of the variable capacity type. It is usually a type of diode called "varicap" whose capacity value is adjustable depending on the DC voltage present at its terminals. The insertion of such a device 140 within a neutralization line allows to change dynamically and at will the frequency band for which the maximum neutralization is obtained.

This solution nevertheless has limitations. In particular, the effective variation of capacity that can be obtained with such a device turns out to be limited, thereby limiting the applications that can be covered with the same antenna system. This solution is therefore not fully satisfactory.

In addition, other solutions have been developed to reduce the coupling between antennas while maintaining a limited space requirement.

Some of these solutions consist in creating in the ground plane slots to limit the transfer of coupling currents between the antennas.

Other of these solutions provide for the use of meta-materials to create notch filters between the antennas due to their properties related to periodicity.

These solutions require specific modifications of the circuit serving as a support for all the electronic components of the object including the card including the printed circuit (PCB), which is penalizing in terms of cost and complexity of implementation.

The present invention therefore aims to provide a miniature antenna system reducing or eliminating at least some of the disadvantages mentioned above. In particular, the invention aims to provide an antenna system in which the electromagnetic coupling between antennas is satisfactory for a greater variety of frequencies, thus allowing a wider range of possible applications while maintaining a small footprint.

SUMMARY OF THE INVENTION

According to one embodiment, the invention relates to a multiple antenna system comprising at least two radiating elements, a first electromagnetic coupling neutralization line between the at least two radiating elements, at least one radio frequency (RF) power supply line. for each radiating element.

The antennal system further comprises:

at least one second electromagnetic coupling neutralization line between said at least two radiating elements, - activation elements of at least part of the neutralization lines, and

Furthermore, the activation elements are configured to selectively activate or deactivate at least a portion of the neutralization lines, so that, depending on their activation / deactivation, the neutralization lines provide a maximum neutralization of the electromagnetic coupling of the radiating elements for a plurality of distinct frequencies.

Thus, depending on the activation / deactivation of at least part of the neutralization lines by said activation elements, a plurality of distinct RF operating modes are obtained for which the insulation of the radiating elements is different and for which no significant electromagnetic coupling is observed between the radiating elements.

Thus, by controlling the activation of the neutralization lines, it reduces or eliminates the electromagnetic coupling between the radiating elements and for different operating frequencies of the radiating elements. Thus, the invention makes it possible to improve the insulation between the accesses of the two radiating elements, this insulation being degraded by the electromagnetic coupling which manifests all the more between two radiating elements that these are close.

It is thus possible to reduce the electromagnetic coupling for distinct and possibly remote operating frequencies.

The invention thus offers the possibility of frequency jumps, thus making it possible to switch easily from one application to another, whatever their respective operating frequencies. For example, by a simple activation / deactivation of the neutralization lines, it is possible to switch from an operating mode based on an operating frequency of 700 MHz to an operating mode based on a frequency of operation of several GHz and obtain for each of these operating modes electromagnetic coupling null or strongly attenuated.

Conversely, the solution described in the patent FR2968845A1 mentioned above allows only to change the operating frequency continuously and in a restricted range.

The invention thus makes it possible to activate very dissimilar personalization elements (neutralization or even short-circuit lines) which can make it possible to obtain large variations in the RF behavior of the antennas.

The invention offers other advantages, among which:

the neutralization lines ensure maximum neutralization of the electromagnetic coupling of the radiating elements for a given frequency, this given frequency depending on the activation / deactivation of the elements activation. Thus by changing the activation / deactivation of the activation elements of the system, the frequency is varied for which the neutralization of the electromagnetic coupling is maximum. Indeed, for each activation / deactivation of the activation elements of the system, the insulation between the radiating elements is varied.

the activation elements are configured to selectively activate or deactivate at least part of the neutralization lines, so that, depending on their activation / deactivation, the neutralization lines allow at least partial isolation between the radiating elements , in order to reduce the electromagnetic coupling between said radiating elements, for a given frequency band.

depending on the activation / deactivation of the activation elements, the configuration of the insulation between the radiating elements is modified thereby modifying the electromagnetic coupling between said radiating elements.

- For a frequency or frequencies or a desired operating frequency band of the radiating elements, the activating elements are activated / deactivated so that the neutralization lines ensure maximum neutralization of the electromagnetic coupling of the radiating elements for said frequency. or said frequencies or said desired operating frequency band.

at least a first and a second short-circuit line to a ground plane of the antenna system, by radiating element and comprising activation elements of at least a part of the short-circuit lines,

at least one neutralization line and preferably all the neutralization lines are devoid of discrete element.

- The at least one neutralization line does not include a discrete element. Thus, and particularly advantageously, the system according to the present invention makes it possible to reduce or even eliminate the losses associated with the discrete components. Furthermore, the fact of proposing an alternative to the use of discrete elements not only makes it possible to reduce losses, but also to increase the efficiency, and therefore the efficiency, by reducing power losses.

In a particularly advantageous manner, the neutralization lines can be operated independently as well as simultaneously. In the case where two neutralization lines are activated and therefore operate at the same time (which implies that some of the activation elements are activated), the decoupling is advantageously in the high working frequency band. AT conversely, when only one neutralization line is activated (implying that some of the activation elements are activated), the decoupling is in the low working frequency band. When a neutralization line is deactivated, the operating frequencies fall.

According to one embodiment, a neutralization line is activated when it is turned on. It thus allows an electrical connection between the two radiating elements. An override line is disabled when it is rendered non-busy. It does not allow an electrical connection between the two radiating elements.

- The control of the neutralization lines, in addition to that of the antennas, by the activation elements, provides a synergy, made possible by the presence of switchable short-circuit tabs. Particularly advantageously, the present invention allows the system to be decoupled in two different operating bands for the radiating elements, i.e. the antennas.

The personalization elements can be numerous, which makes it possible to potentially obtain many different RF operating modes. Thus, even with only two antennas compact on the same ground plane we can obtain the following modes of operation: diversity, multi-port, multi-standard.

The solution of the patent FR2968845A1 with use of a varicap diode requires that it is known to generate in an analog manner the DC voltage which must be applied to its terminals in order to obtain the value of capacity desired for the application. The present invention makes it possible to have a numerical control, that is to say a binary or ON / OFF, which activates pre-established RF operating modes and which will be much less likely to derive than an analog system with a variable capacity on which must be applied a variable DC voltage. To improve the reliability of the solution of patent FR2968845A1, it would produce a variable DC voltage and enslave to achieve a non-drifting operation, but it would be very detrimental in terms of costs.

Optionally, the invention may further include at least any of the following optional features taken separately or in combination:

Advantageously, said activation elements are configured so as to allow the simultaneous activation of at least the first neutralization line and the second line of neutralization. Particularly advantageously, the first neutralization line and the second neutralization line are actuated simultaneously by said activation elements. More generally, the system is configured so that at least two neutralization lines are activated simultaneously. In a nonlimiting embodiment, at least one of the neutralization lines is always activated, that is to say that it is always connected to the two radiating elements. In this embodiment, the neutralization line, preferably, then does not include an activation element connecting it to the radiating elements but a simple permanent connection.

Advantageously, the neutralization lines are configured so that, depending on their activation / deactivation, they ensure a maximum neutralization of the electromagnetic coupling of the radiating elements for a plurality of distinct and separate frequencies for at least two of them and of preferably at least a factor of 1.2 and preferably at least a factor of 1.5 and preferably at least a factor of 2.

Thus, it is possible for example by a simple switching neutralization lines performed by the activatable elements to go from a maximum attenuation of the coupling for a frequency of 1 GHz to a maximum attenuation of the coupling for a frequency of 1.1 GHz or 1.2 GHz or 1.5GHz or 2GHz.

According to one embodiment, the system comprises at least one short-circuit line to a ground plane of the antenna system per radiating element.

According to one embodiment, the system comprises at least one additional short-circuit line per radiating element. According to one embodiment, the antenna system comprises binary activation elements of at least a part of the short-circuit lines.

According to one embodiment, the binary activation elements are configured to independently enable or disable the neutralization and short-circuit lines to the ground plane.

Advantageously, each of the neutralization lines has a geometry, in particular a length, a width, a shape and a thickness, shaped to ensure neutralization of the electromagnetic coupling of the radiating elements for at least one frequency and preferably for a plurality of frequencies. A neutralization line, according to the present invention, by its geometry, can behave, for example, as a capacitance, an inductance or an impedance, depending on the frequency. According to one embodiment, at least two neutralization lines connecting the same two radiating elements have lengths and / or different shapes.

Preferably, at least one neutralization line of the first and second neutralization lines consists of a tab or a microstrip line. A micro-ribbon line is for example an electrical line, serving as a guide to an electromagnetic wave propagation, consisting of a conductive ribbon deposited on a dielectric substrate whose second metallized face acts as a ground plane. Advantageously, the neutralization line does not include a discrete element, which makes it possible to reduce the losses. According to an advantageous embodiment, all the neutralization lines consist solely of a tongue or a micro-ribbon line.

According to one embodiment, the activation elements are binary activation elements.

In one embodiment, the activation elements, also referred to as switching elements, are configured to selectively enable or disable each of the disabling lines. They thus make it possible to ensure decoupling for a maximum frequency which depends on the activation of the neutralization lines.

Advantageously, at least one of the activation elements is a PIN diode. Advantageously, all the activation elements are PIN diodes.

Advantageously, at least the activation elements of at least a part of the neutralization lines are polarized PIN diodes using a continuous signal (DC) superimposed on the RF signals conveyed by the system to selectively make the conductor the PIN diode and allow the radiating element to which it is attached to become active, or to make the PIN diode non-conductive so that the radiating element to which it is attached becomes inactive.

Alternatively, at least some of the activation elements of at least a portion of the neutralization lines are varicap type diodes.

According to one embodiment, the system comprises two radiating elements and comprises two neutralization lines interconnecting said two radiating elements.

According to one embodiment, the system comprises at least two radiating elements and comprises at least three neutralization lines interconnecting said two radiating elements. According to one embodiment, the neutralization lines are suspended between the radiating elements. The neutralization lines are arranged at a distance from the ground plane.

Alternatively, the neutralization lines are printed on an electronic card carrying the radiating elements.

According to a particular embodiment, the neutralization lines are integrated or printed in a layer. The system then forms a stack of superimposed layers without intermediate empty space between the layers and one layer of which forms the ground plane and another layer of which comprises the neutralization lines and the radiating elements. This simplifies the realization of the system and its industrialization.

Alternatively, the neutralization lines are formed in part by the ground plane, to which are connected conductive elements connected to the radiating elements and in part by these conductive elements.

According to a particular embodiment, the system comprises at least three radiating elements and a plurality of neutralization lines interconnecting the radiating elements.

According to a particular embodiment, at least some and preferably all the radiating elements each have a general shape of tongue and have the following dimensions:

a length between h / 2 and λ / 6 and preferably λ / 4, a width between λ / 10 and λ / 20 and preferably λ / 20, a height between λ / 30 and λ / 15 and preferably between λ / 28 and λ / 20;

λ being the wavelength of the signal that the radiating element is intended to receive / transmit.

Preferably, the length is measured according to the largest dimension of the tongue. Preferably, the width corresponds to the width of the tongue. Preferably, the height corresponds to the distance between the tongue and the ground plane, the tongue extending in a plane parallel to that in which the ground plane extends.

According to one embodiment, each neutralization line is associated with supply lines of the radiating elements.

According to one embodiment, the neutralization lines are associated with connection lines to the ground plane of the radiating elements. According to one embodiment, the ground plane means comprise a printed circuit board.

According to one embodiment, the radiating elements are of PIFA type.

According to another embodiment, the invention relates to an antenna system comprising elements forming a ground plane and at least two radiating elements and a first coupling neutralization line of the radiating elements, characterized in that it comprises at least one second coupling neutralization line of the two radiating elements. The system further includes activation elements configured to selectively enable or disable each of the neutralization lines, thereby providing electromagnetic decoupling for a maximum frequency that depends on activation of the neutralization lines by the activation elements. .

Preferably, the activation elements are configured to selectively activate or deactivate each of the neutralization lines by respectively passing or not passing each of the neutralization lines.

Preferably, the first coupling neutralization line of the radiating elements has a first electromagnetic property, typically a first impedance or a first inductance, and the second coupling neutralization line of the two radiating elements has a second electromagnetic property different from the first, typically a second impedance or a second inductance different from the first.

Another aspect of the present invention relates to a telecommunication apparatus comprising a multiple antenna system according to any one of the embodiments of the invention. The apparatus also includes a receiver and / or transmitter coupled to said multiple antenna system. The telecommunication apparatus may be an apparatus for receiving and / or transmitting wireless communications. It is for example a mobile phone.

BRIEF DESCRIPTION OF THE FIGURES

The objects, objects, as well as the features and advantages of the invention will become more apparent from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which:

FIGURE 1 illustrates an antennal system of the prior art. FIGS. 2a and 2b illustrate an antenna system according to an embodiment of the invention including a neutralization line and diode-programmable short-circuit lines. In this embodiment, the system comprises two radiating elements and two neutralization lines.

FIG. 3 illustrates the operation of the dual antenna system according to the invention operating in the PDC frequency band.

FIGURE 4 illustrates the operation of the dual antenna system according to the invention operating in the GPS frequency band.

FIGURE 5 illustrates the operation of only one of the two antennas in the PDC frequency band.

FIGURE 6 illustrates the operation of only one of the two antennas in the GPS frequency band.

FIGURE 7 shows an implementation of the invention with neutralization lines of various sizes and shapes.

FIGURE 8 shows an implementation of the invention comprising more than two radiating elements separated by more than one neutralization line.

The drawings are given by way of examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily at the scale of practical applications. In particular, the relative dimensions of the different elements are not representative of reality.

DETAILED DESCRIPTION OF THE INVENTION

Figures 2a and 2b describe an example of antenna system according to the invention.

The invention consists in improving the technique of the neutralization line described in FIG. 1 by using simple binary switching components which can then be directly controlled by a digital circuit without the need to generate an analog DC voltage as is necessary with a varicap diode. The binary switching components that may be suitable include, in particular, the so-called PIN diodes which include, in addition to the P-type and N-type doped zones of a conventional diode, an undoped or intrinsic intermediate zone (I). Such a structure, polarized in the forward direction, advantageously has an extremely low dynamic impedance for the RF signals that pass through it. Polarized in the opposite direction, that is to say blocked, it then has on the contrary a very high impedance with a very low capacity. These diodes, which can be directly controlled by a digital circuit integrated circuit type (IC) 101, can easily change, on the fly, the behavior of PIFA antennas without using the varicap diode type components as described in Figure 1.

To obtain this result, the invention combines the use of diodes, on the one hand, with several spatial arrangements of the short-circuit lines, 212 and 222, radiating elements; and on the other hand, with the addition of at least one second switchable neutralization line 230 in addition to the first neutralization line 130.

By neutralization line is meant a line connected between two radiating elements 1 10, 120 allowing, when passive, to isolate or improve the insulation between the supply ports of two radiating elements in order to reduce the observed coupling between said radiating elements 1 10, 120, for a given frequency band.

In a particularly advantageous manner, at least one neutralization line 130, 230 does not comprise a discrete element. Advantageously, the neutralization line 130, 230 consists of a micro-ribbon line. According to another embodiment, the neutralization line 130, 230 consists of a tab. The neutralization line 130, 230 is advantageously in the form of a metal ribbon. It does not have a discrete element. Only its extremities are connected to the activation elements which will be defined in detail below and which make it possible to activate or deactivate the neutralization line.

Advantageously, each of the neutralization lines has a geometry, in particular a length, a width, a shape and a thickness, shaped to ensure neutralization of the electromagnetic coupling of the radiating elements for at least one frequency and preferably for a plurality of frequencies. A neutralization line, according to the present invention, by its geometry, can behave, for example, as a capacitance, an inductance or an impedance, depending on the frequency.

To configure a neutralization line, in particular to determine its geometry and so that it can ensure effective neutralization at the desired frequency or frequencies, it will be possible for example to refer to the following publications:

"Study and Reduction of the Mutual Coupling Between Two Mobile Phone PIFAs Operating in the DCS1800 and UMTS Bands", published in IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 54, NO.

1 1, NOVEMBER 2006, p. 3063-3074, and whose authors are Aliou Diallo, Cyril Luxey, Philippe Thuc, Robert Staraj, and Georges Kossiavas. For example, see sections IV A and IV B.

- "MULTI-ANTENNA SYTEMS FOR DIVERSITY AND MIMO" doctoral thesis of Aliou DIALLO, UNIVERSITY NICE-SOPHIA ANTIPOLIS, 2007. This thesis is available in particular at the following database: https://tel.archives-ouvertes.fr/ tel-00454612 / document. For example, refer to pages 90 to 100.

The radiating elements are, for example, PIFA antennas described in FIG.

The diodes are six in number, bearing the references 241 to 246, in the particular example of Figure 2 which is only a specific non-limiting example of implementation of the invention.

These diodes are typically, as shown, discrete components weldable to the various metallic elements constituting PIFA antennas used in this example to illustrate an implementation of the invention.

The switching between the multiple possible physical configurations thus obtained, by means of an adequate polarization of the diodes, makes it possible to selectively activate or deactivate the short-circuits and the neutralization lines, and thus to control individually the frequencies at which the antennas are both adapted and isolated. The neutralization is thus adjusted so as to simultaneously obtain an adequate decoupling of the two radiating elements for each operating mode of the antennal system. The global structure can thus adopt several behaviors precisely defined by the applications considered: diversity, multistandards or multi-access.

In Figure 2a, to illustrate a particular example of implementation of the invention, the components used are PIN diodes. The binary behavior of these diodes, used in the on or off state, is set by a DC voltage greater or less than a threshold voltage applied directly across them. In a simple implementation making it possible to obtain switching of the diodes, it is advantageous, for example, to directly inject the DC voltage at the access ports of the antennas 21 1 and 221. The DC voltage injected into the antennal system does not disturb the RF signal to be radiated by the antennas.

In the case of complex systems involving multiple diodes, such as that illustrated in Figure 2a, it is necessary to create the RF / DC decoupling which allow to adequately polarize the customization diodes. The example of FIG. 2 shows the use of two distinct locations for the short-circuit tabs 212 and 222 of each antenna which are programmable by means of activation elements, advantageously diodes 241. to 244, as well as the use of two neutralization lines, one fixed 130 and the other programmable 230 using activation elements 245, 246. Advantageously, the activation elements are diodes.

All configurations illustrated in Figure 2a are therefore achievable through the use of six diodes 241 to 246 in this example. They make it possible to activate or deactivate any short-circuit tabs 212 and 222 as well as the second neutralization line 230. The first line 130, which is fixed, always connects in this example the radiating elements 1 10 and 120, of the two antennas.

In a nonlimiting embodiment such as that illustrated in FIG. 2a, at least one of the neutralization lines, the line 130 in the embodiment of FIG. 2a, is always activated, that is to say that it is always connected to the two radiating elements 1 10, 120. In this embodiment, the neutralization line 130 does not then include an activation element connecting it to the radiating elements 1 10, 120 but a simple permanent connection.

The following nonlimiting example shows how one can choose a desired mode of operation of the multi-antenna system, even in the case of two very close standards (PDC and GPS):

- the so-called PDC (personal digital cellular) tape, referring to a standard mainly implemented in Japan, ranging from 1465 to

1501 MHz, a 36 MHz band centered on 1483 MHz.

- the GPS band (standard already mentioned), ranging from 1555 to 1595 MHz, ie a 40 MHz band centered on 1575 MHz.

In the example of the antenna system of FIG. 2a, it is possible, with the aid of the six diodes, to make already four combinations of antennas appearing in the table below.

In this table the diodes, whose reference is on the first line, are polarized to pass if there is a "1" in the corresponding box and blocked if there is a "0".

__ CM 00 LO CD

Name: CM CM CM CM CM CM Function:

Div1 1 0 1 0 0 0 Diversity: 2 antennas in the PDC band

Div2 0 1 0 1 1 1 Diversity: 2 antennas in the GPS band

MultM 1 0 0 0 0 0 Multi-port: 1 PDC antenna

Multi2 0 0 0 1 1 1 Multi-port: GPS antenna 2 In the example "Div2", the diodes 242, 244, 245, 246 are activated ("ON" state). In this example, a diversity behavior is obtained with the two radiating elements 1 10, 120 in the same band (GPS). The second neutralization line 230 decouples the operation of the radiating elements 1 10, 120 for these high frequencies.

In the example "Multi 1", only a diode 241 is activated. The system thus only operates at the PDC frequency at the access port 21 1. If only the diode 243 is activated, the system also operates only at the PDC frequency but by another access port 221. The PDC standard has two separate access ports. This "Multi 1" solution combines with the solution of the "Multi2" example (activation of the diodes 244, 245, 246 for operation at the GPS frequency by the access 221, activation of the diodes 242, 245, 246 for a operation at the GPS frequency by the access 21 1) so as to form a multi-port system.

The present invention therefore makes it possible to propose a multi-standard, multi-port system that can operate in diversity. This is made possible by the independent actuation but also and advantageously simultaneously of the neutralization lines 130, 230. In order to facilitate the manufacture of the antenna system of FIG. 2a and to ensure its robustness, the radiating metal elements 10 and 120 and the neutralization lines, 130 and 230, may be part of a raised printed circuit board 102 on which will also be solder the customization diodes 245 and 246. The RF supply lines of the antennas, 21 1 and 221, as well as the short-circuit lines of the antennas PIFA, 212 and 222, will then be metal vias crossing the dielectric of the printed circuit 102 to be connected to the PCB 100 supporting the integrated circuit. The thickness 103 of the circuit 102 will be adapted to meet the geometric characteristics defined for the PIFA antennas considered.

FIG. 2a shows how the diodes 241 to 246 are electrically connected in this exemplary implementation of the invention.

Figure 3 shows the feasibility of the concept.

A strong electromagnetic coupling between two adjacent radiating elements results in a generally high value of the transmission coefficient between the two antennas said S21 310 measured or simulated between the two access ports 21 1 and 221. In this figure, it can be seen that the fixed neutralization line 130 makes it possible to obtain a significant drop in the coefficient S21, and thus to obtain a strong isolation between access (thus a weak electromagnetic coupling) for the working frequencies of the antennas operating in the PDC band centered on 1, 483 GHz. These simulation results are obtained by activating the short-circuit lines of the PIFA antennas corresponding to the diodes 241 and 243 according to the table above. We note a functioning in diversity with the two antennas operating in the same band, the so-called PDC in this case.

It will be noted here that the parameter S21 corresponding to the curve 310, is part of the so-called S parameters of the English "scattering parameters" or "S-parameters" widely used in microwave to characterize in particular the behavior of passive or active dipoles. These parameters are used to measure the values of the incident waves, reflected and transmitted by the quadrupoles studied. As indicated above, S21 measures in this case the transmission coefficient between antennas. The two almost superimposed curves 320 correspond, for their part, to the so-called parameters S1 1 and S22, also called reflection coefficients of each of the antennas.

FIG. 4 shows the simulation results obtained with diodes 242,

244, 245 and 246 activated in their on state as shown in the table above. There is indeed a diversity behavior with the two antennas operating in the same frequency band, that said GPS this time centered on 1, 575 GHz. The activation of the second neutralization line 230, using the diodes 245 and 246, makes it possible to decouple the antennas for these higher frequencies than the previous ones in combination with the activation of the short-circuit lines of the corresponding PIFA antennas. to the diodes 242 and 244. We find in this figure the same type of curves as in the previous figure, that is to say the parameter S21 410 corresponding to the transmission coefficient between the two antennas and the parameters S1 1 and S22 or reflection coefficients of each of the antennas corresponding to the superimposed curves 420.

With reference to FIG. 2b, it will be noted here that the polarization of the diodes 245 and 246 may require the application of an intermediate independent polarization on the neutralization line 230 which will act only in DC. For example, this may take the form of a fine conductive vertical wire 231 connected to the ground plane of the PCB. At the transmitted frequencies, which are expressed in GHz, the vertical wire 231 allowing the DC bias of the line 230 and therefore those of the diodes 245 and 246, can advantageously be designed and dimensioned such that it constitutes only a "coil of 'stop' or 'shock choke' for RF signals transmitted or received. It may also be combined with a discrete component (not shown) to provide a choke-off function for the transmitted RF signals. FIG. 5 shows the results obtained with only the activation of the diode 241 and the corresponding short-circuit line 212. The system thus operates only at the frequencies of the PDC band on the only antenna whose radiating element is 1 10. This solution optionally combines according to the applications with the case of FIG. 6 which follows in which the diodes 244, 245 and 246 are activated in their on state so as to activate the second neutralization line 230 and the short-circuit line 222 corresponding to the diode 244, to allow the operation of the only antenna whose radiating element is 120 in the band of GPS frequencies in this case, thus forming a multiport system (PDC or GPS). We find in these figures the S parameters already described.

The invention therefore makes it possible to propose a multistandard and multiport system that can also operate in diversity. All of these features are realized with only two compact antennas close to each other and some simple low-cost components (PIN diodes) widely used by the electronics industry. This innovation drastically reduces the complexity of transmission systems traditionally using more antennas with reduced performance because of the electromagnetic coupling existing between antennas located close to each other on the same PCB.

The technique of the invention can easily be extended to other frequency bands and apply to multiple wireless communication technologies. It is also possible to add other switchable shorting lines on each antenna to work on a larger number of frequency bands simultaneously. In this case, the addition of one or more switchable neutralization lines may be necessary.

The exemplary antenna system illustrated in FIGS. 2a and 2b will now be described in more detail. Each antenna has a general shape of tongue. Each tab has the following dimensions, where λ is the wavelength of the signal emitted / received by the radiating element:

A length between h / 2 and λ / 6 and preferably λ / 4. Preferably, the length is measured according to the largest dimension of the tongue.

A width of between λ / 10 and λ / 20 and preferably of λ / 20. Preferably, the width corresponds to the width of the tongue. A height of between λ / 30 and λ / 15 and preferably between λ / 28 and λ / 20. The height corresponds to the distance between the plane in which extends the tongue and the ground plane, typically the integrated circuit the printed circuit for receiving the other electronic components. More precisely, for each application the signal is included in a frequency band and λ corresponds to the central frequency of the frequency band.

More generally, the central operating frequency range of the system according to the invention can typically range from 700 MHz to about 6 GHz. The system can thus be applied to all the standards operating on this frequency band including the following standards: LTE, GSM, DCS, PCS, UMTS, GPS, WiFI, Bluetooth, Zigbee, WLAN, etc.

Among all the possible implementations of the invention two are more particularly illustrated in the figures which follow.

FIG. 7 shows the possible use of one or more additional neutralization lines 731 and 733 in addition to the line 130. In this nonlimiting example the line 130 is fixed, that is to say that it is always activated (always connected to the two radiating elements). Naturally, the invention also encompasses systems in which all lines are non-fixed, that is, activatable or deactivatable.

In general, all the neutralization lines may be of various shapes and sizes that are best adapted by those skilled in the art, in particular with a view to obtaining a minimum coupling between antennas for the applications considered in a manner similar to that which has been described for antennas of the GPS and PDC bands in the previous figures. As before, the neutralization and short-circuit lines may optionally be fixed, or programmable in particular using diodes (not shown in this figure), in order to obtain several modes of operation from the same antennal system according to the invention.

Figure 8 illustrates the case where the antennas and their radiating elements have been multiplied. In the example of FIG. 8 there are four of them: 810, 820, 830 and 840. In this case they are separated by three neutralization lines 835, 837 and 839. To complete the four PIFA antennas of this example, found, as previously, the RF signal feed lines: 81 1, 821, 831 and 841, constituting the input ports of the antenna system, and the short-circuit lines: 812, 822, 832 and 842. As above, short-circuit and Additional programmable overrides (not shown) may optionally also be present in this structure.

In another embodiment not illustrated, at least some of the radiating elements are interconnected by several neutralization lines.

In view of the foregoing description, it is clear that the invention proposes a simple solution that is reliable over time and that in particular offers the following advantages:

- Possibility of activating highly dissimilar personalization elements (neutralization and short-circuit lines) which can make it possible to obtain large variations in RF behavior of the antennas (diversity, multi-port, multi-standard operation), and this even with two antennas only on the same ground plane and in a small footprint.

- Possibility of frequency jumps, even for distant frequencies, to cover many potentially very different applications. The customization elements can be numerous one can potentially obtain many RF operating modes possibly very different.

- Simple activation by means of a binary command (ON / OFF) of carefully precomputed elements which are not likely to vary in time depending, for example, on the environment.

- Lower cost insofar as the binary signals coming directly from the integrated circuit can be used directly.

- Improved compactness. With equal performance, without neutralization line, it would indeed be necessary that the elements are further apart from each other.

The invention is not limited to the previously described embodiments and extends to all the embodiments covered by the claims.

In particular, although it has been explained above the advantages of using activation element in the form of PIN diodes to selectively activate / deactivate the neutralization lines, all the previously described embodiments can use Varicap diodes as an alternative or in combination with the PIN diodes.

Moreover, although in the figures the radiating elements are identical, the invention covers the embodiments in which the radiating elements of the same system are different.

Claims

1. Multiple antenna system having at least two radiating elements (1 10, 120), a first electromagnetic coupling neutralization line (130) between the at least two radiating elements (1 10, 120), at least one power supply line radio frequency (RF) (21 1, 221) for each radiating element (1 10, 120),

characterized in that the antenna system further comprises:

at least one second electromagnetic coupling neutralization line (230, 731, 733) between said at least two radiating elements (1 10, 120); and,

activation elements (241 to 246) of at least a portion of the neutralization lines (130, 230, 731, 733) and,

at least first and second short-circuit lines (212, 222) to a ground plane (100) of the antenna system, per radiating element

(1 10, 120) and having activation elements (241 to 246) of at least a portion of the short-circuit lines (212, 222),

and in that the activation elements (241 to 246) are configured to selectively activate or deactivate at least a portion of the neutralization lines (130, 230, 731, 733) so that depending on their activation / deactivation, the neutralization lines (130, 230, 731, 733) ensure maximum neutralization of the electromagnetic coupling of the radiating elements (1 10, 120) for a plurality of frequencies.

2. System according to the preceding claim wherein the neutralization lines (130, 230, 731, 733) are devoid of discrete element.

The system of any preceding claim wherein said activation elements (241 to 246) are configured to enable simultaneous activation of at least the first neutralization line (130) and the second line of neutralization (230, 731, 733).

4. System according to any one of the preceding claims wherein at least one neutralization line (130, 230, 731, 733) consists of a tab or a microstrip line.

5. System according to any one of the preceding claims wherein all the neutralization lines (130, 230, 731, 733) consist of a tab or a microstrip line.

6. System according to any one of the preceding claims wherein the neutralization lines (130, 230, 731, 733) are configured so that depending on their activation / deactivation they ensure maximum neutralization of the electromagnetic coupling of radiating elements (1 10, 120) for a plurality of distinct frequencies and separated from each other by at least a factor of 1 .1 and preferably by at least a factor of 2.

A system according to any one of the preceding claims wherein the activation elements (241 to 246) are configured to independently enable or disable the neutralization (130, 230, 731, 733) and short-circuit (212) lines. , 222) to the ground plane.

8. System according to the preceding claim wherein the activation elements (241 to 246) are binary activation elements.

9. System according to any one of the preceding claims wherein each of the neutralization lines (130, 230, 731, 733) has a geometry, in particular a length, a width, a shape and a thickness, shaped to ensure neutralization. electromagnetic coupling of the radiating elements (1 10, 120) for at least one frequency.

10. System according to any one of the preceding claims wherein at least two neutralization lines (130, 230, 731, 733) connecting the same two radiating elements (1 10, 120) have different lengths and / or shapes.

1 1. A system as claimed in any one of the preceding claims wherein the activation elements (241 to 246) are binary activation elements.

The system of any preceding claim wherein the activation elements (245, 246) are configured to selectively enable or disable each of the disabling lines.

The system of any preceding claim wherein at least one of the activation elements (245, 246) is a PIN diode.

14. System according to the preceding claim wherein all the activation elements (245, 246) are PIN diodes.

System according to any one of the preceding claims wherein at least the activation elements (245, 246) of at least a part of the neutralization lines (130, 230, 731, 733) are PIN diodes polarized at using a continuous signal (DC) superimposed on the RF signals conveyed by the system to selectively make the PIN diode conductive and allow the radiating element (1 10, 120) to which it is attached to become active, or non-conducting the PIN diode so that the radiating element (1 10, 120) to which it is attached becomes inactive.

16. System according to any one of the preceding claims comprising two radiating elements (1 10, 120) and comprising two neutralization lines (130, 230) interconnecting said two radiating elements (1 10, 120).

17. System according to any one of claims 1 to 15 comprising at least two radiating elements (1 10, 120) and comprising at least three neutralization lines (130, 731, 733) interconnecting said two radiating elements (1 10 , 120).

18. System according to any one of the two preceding claims wherein at least one (130) of the two neutralization lines (130, 230) is permanently activated.

19. System according to any one of the preceding claims wherein the neutralization lines (130, 731, 733) are suspended between the radiating elements (1 10, 120) and at a distance from the ground plane (100).

20. System according to any one of claims 1 to 18 comprising a stack of superposed layers without intermediate empty space and one layer of which forms the ground plane and another layer of which comprises the neutralization lines and the radiating elements.

21. A system according to any one of the preceding claims comprising at least three radiating elements (810, 820, 830, 840) and a plurality of neutralization lines (835, 837, 839) interconnecting the radiating elements (810, 820, 830). , 840).

22. System according to any one of the preceding claims wherein at least some and preferably all the radiating elements (1 10, 20, 810, 820, 830, 840) each have a general shape of tongue and have the following dimensions:

a length of between h / 2 and λ / 6 and preferably of λ / 4,

a width between λ / 10 and λ / 20 and preferably λ / 20, a height between λ / 30 and λ / 15 and preferably between λ / 28 and λ / 20;

λ being the wavelength of the signal that the radiating element (1 10, 20, 810, 820, 830, 840) is intended to receive / transmit.

A telecommunications apparatus comprising a multiple antenna system as claimed in any one of the preceding claims and comprising a receiver and / or transmitter coupled to said multiple antenna system.