EP1548881B1 - Planar radiating surface antenna and portable telephone comprising the same - Google Patents

Description

The present invention relates to an antenna of the type having flat radiating surfaces.

The invention proposes in particular an antenna of this type comprising radiating surfaces whose functions of certain parts are able to be reversed according to the conditions of use.

It also offers a mobile phone structure comprising such an antenna.

STATE OF THE ART

It has already been proposed to use for mobile telephones flat antennas called PIFA ("Planar Inverted-F Antenna" or flat antenna type F inverted) which comprise, as shown in Figure 1, a ground plane 1 and a planar conductive surface 2 which is superimposed on this ground plane 1, and extends straight and parallel thereto. Such an arrangement has a resonance wavelength which is a function of the dimensions of the plane conductive surface 2 and the height which separates it from its ground plane 1.

As shown in Figure 2, an antenna of this type is easily integrated into a mobile phone 5 having a keyboard 4 and a screen 3.

In particular, the ground plane 1 is constituted by the printed circuit located inside the housing of the telephone 5, behind the screen 3 and the keyboard 4. The radiating surface 2 is generally placed at the rear of the housing phone 5.

It is understood that these antennas have a significant advantage in terms of size.

In addition, this kind of antenna offers good radiation performance, especially in far-field measurement, while locally producing a lower near field than whip antennas or helical antennas also known to those skilled in the art.

However, and as illustrated in Figure 3, a defect of this kind of antenna is the dissymmetry of the radiation pattern.

The radiation lobe 20 on the side of the radiation surface 2 is larger than the lobe 10 on the side of the ground plane 1. The difference between the two lobes 10 and 20 is of the order of about 3 dB.

This asymmetry is more or less pronounced depending on the immediate environment of the antenna, namely the presence of metal parts, the dimensions of the mobile, etc.

Thus, as illustrated in FIG. 4A, when the telephone 5 is in use, the radiation lobe 20 is larger on the opposite side to the user's head 6 and the lobe 10 is smaller on the side of the head 6 of the user.

In this case of use of the telephone 5 at the head 6 of the user, the dissymmetry of the lobes 10 and 20 of radiation is rather beneficial.

However, FIGS. 4B to 4D show use cases in which asymmetry causes problems in the operation of the telephone 5.

Indeed, when the phone 5 is buried in a pocket 7 as in the case of Figure 4B, or placed on a table 8 as shown in Figure 4C, or held in hand 9 as in Figure 4D, the surface 2 located at the back of the phone 5 is hidden. The connection between the telephone 5 and the base station of the network is therefore bad.

Figures 2 to 4D show a one-piece telephone. However, it is understood that the situation is identical for phones with two components or phones "clam" according to the English terminology generally used by those skilled in the art.

FIGS. 5A to 5C also illustrate a telephone case 5 with a particular architecture, for example a clam telephone with a 360 ° opening and comprising two flaps referenced 51 and 52.

In the example of FIGS. 5A to 5C, the surface 2 is located in the flap referenced by 52.

Thus, in FIG. 5A, the flap 51 of the telephone 5 is for example placed on a table 8, the flap 52 being in the closed position on the flap 51. surface 52 is therefore well located with respect to table 8 and the connection of the telephone 5 with the base station of the network is good.

By cons, in the case of Figure 5B, the two flaps 51 and 52 are placed on the table 8, and because of the position of the surface 2 at the rear of the flap 52, the antenna is hidden. It is substantially in the case of Figure 4C with a monobloc phone.

The operation of the telephone 5 is even worse in the case of Figure 5C, when the flap 52 is in the closed position under the flap 51. The surface 2 is completely hidden. The radiating behavior of the surface 2 is modified due to the presence of metal and / or plastic parts in the telephone 5.

Thus, in the case of a monobloc phone or a clam, 360 ° opening or not, the dissymmetry of the radiation pattern poses connection problems.

Some known techniques propose to solve the problem of poor connection with the base station of the network by positioning two antennas PIFA in the phone, one antenna being located at the front of the phone housing, and another at the back of the housing.

Switching means enable one or the other of the antennas to be operated according to the configuration and the position of the telephone. Thus, the phone always has a well placed antenna for its transmission / reception.

These motions for resolution, however, are not entirely satisfactory.

Indeed, having two antennas in the phone increases the size of the phone. Two antennas are indeed bulky.

In addition, having two antennas in the phone increases its cost.

The document EP 1 160999 discloses an antenna that allows switching of certain parts of the antenna, but does not allow control of the radiation front / back of the antenna relative to the housing of the phone. A large constant mass plane is arranged under the all switchable parts. The switchable parts overlap the large ground plane throughout their area.

There can therefore be no pronounced inversion of the direction of radiation of the antenna.

PRESENTATION OF THE INVENTION

One of the aims of the invention is to propose an antenna and a telephone comprising such an antenna that overcomes at least one of the disadvantages of antennas and telephones of the prior art.

One of the aims of the invention is notably to propose an antenna and a telephone which can have a good connection with a base station of the network whatever the configuration of the telephone or its position of use.

One of the aims of the invention is, in particular, to propose an antenna and a telephone having a symmetrical behavior with respect to a base station of the network.

One of the aims of the invention is to propose a telephone having only one antenna.

For this purpose, the invention provides an antenna according to claim 1.

The invention thus proposes a transmitting / receiving antenna comprising a ground plane and at least one plane radiation surface, characterized in that it comprises a ground reference partial area, at least two flat surfaces extending in parallel. thereto and switching means electrically connecting the reference partial area to alternately one of the planar surfaces, thereby defining a switching between a first configuration and a second configuration, the first configuration corresponding to a situation in which one of the planar surfaces constitutes the radiation surface, the entire ground plane then comprising the reference partial area and the other flat surface, the second configuration corresponding in turn to a situation in which the radiation surface of the first configuration is electrically connected to the area partial reference to form the plan of mass, the other flat surface then playing the role of radiation surface.

The flat surfaces overlap the partial area at most over a negligible area in front of the area of said surfaces.

Preferred embodiments are set forth in the dependent claims.

• la zone partielle de référence de masse est constituée par tout ou partie d'un circuit imprimé apte à être placé dans un téléphone ;
• les deux surfaces planes sont de mêmes dimensions et sont situées symétriquement par rapport à un plan contenant la zone partielle de référence de masse ;
• les surfaces planes sont des plaques métalliques ;
• les moyens de commutation sont aptes à former des circuits électriques ouvert ou des circuits électriques fermés ;
• les moyens de commutation comportent au moins une diode PIN ;
• les moyens de commutation comportent au moins une diode active ;
• les moyens de commutation comportent des microsystèmes électromécaniques de technologie MEMS.

The invention is advantageously completed by one of the following characteristics, taken alone or in any technically possible combination:

• the partial reference area of mass is constituted by all or part of a printed circuit adapted to be placed in a telephone;
• the two plane surfaces have the same dimensions and are located symmetrically with respect to a plane containing the ground reference partial area;
• flat surfaces are metal plates;
• the switching means are able to form open electrical circuits or closed electrical circuits;
• the switching means comprise at least one PIN diode;
• the switching means comprise at least one active diode;
• the switching means comprise electromechanical microsystems of MEMS technology.

The invention also relates to a telephone comprising such an antenna.

The invention has many advantages.

It allows in particular a pronounced inversion of the direction of radiation of the antenna. Depending on the switching, the antenna radiates mainly towards the front part or mainly towards the rear part of the telephone case.

PRESENTATION OF FIGURES

• la figure 1, déjà discutée, représente schématiquement une antenne de type PIFA conforme à un état de la technique connu ;
• la figure 2, également déjà discutée, est une représentation schématique de face et de profil d'un téléphone connu;
• la figure 3, déjà commentée, est une représentation schématique d'un graphe du diagramme de rayonnement d'une antenne connue ;
• les figures 4A à AD, déjà commentées, sont des représentations schématiques de positions d'utilisation d'un téléphone connu ;
• les figures 5A à 5C, déjà commentée, sont des représentations schématiques de configurations d'utilisation d'un téléphone à deux volets connu ;
• les figures 6A et 6B sont des représentations schématiques des configurations d'une antenne selon l'invention ;
• la figure 7 montre une disposition possible des surfaces planes ainsi que de la zone partielle de référence de masse d'une antenne selon l'invention ;
• la figure 8 représente schématiquement les jonctions entre les deux surfaces planes et la zone partielle de référence ;
• les figures 9A à 10B montre la situation de la surface rayonnante dans plusieurs positions d'utilisations et pour plusieurs configurations de téléphones.

Other features and advantages of the invention will become apparent from the description which follows, which is purely illustrative and nonlimiting and should be read with reference to the accompanying drawings in which:

• FIG. 1, already discussed, shows schematically a PIFA type antenna according to a known state of the art;
• Figure 2, also already discussed, is a schematic representation of front and side of a known phone;
• Figure 3, already commented, is a schematic representation of a graph of the radiation pattern of a known antenna;
• FIGS. 4A to AD, already commented on, are schematic representations of positions of use of a known telephone;
• FIGS. 5A to 5C, already commented on, are schematic representations of configurations for using a known two-part telephone;
• Figures 6A and 6B are schematic representations of the configurations of an antenna according to the invention;
• FIG. 7 shows a possible arrangement of the flat surfaces as well as the partial ground reference area of an antenna according to the invention;
• FIG. 8 schematically represents the junctions between the two plane surfaces and the reference partial area;
• FIGS. 9A to 10B show the situation of the radiating surface in several positions of use and for several configurations of telephones.

In all the figures, the elements having a similar function have identical reference numerals.

DETAILED DESCRIPTION

The antenna shown in FIG. 6A comprises a ground plane 1 and at least a plane radiation surface 2.

According to the invention, the antenna more precisely comprises a reference area 60 of mass and at least two plane surfaces 61 and 62 extending parallel to the reference portion 60 of mass. In FIG. 6A, the surface 61 is located in the extension of the zone 60, whereas the surface 62 is remote from the zone 60 in a perpendicular direction.

The antenna also comprises switching means 63 electrically connecting the reference partial zone 60 to alternately one of the plane surfaces 61 and 62.

The switching means 63 thus define a switching between a first configuration and a second configuration.

The first configuration is visible in Figure 6A and corresponds to a situation in which one of the planar surfaces - here the surface 62 - constitutes the radiation surface. It is therefore this surface 62 which in the first configuration defines the frequencies of radiation of the telephone.

The whole mass plane 1 then comprises in the first configuration the reference partial zone 60 and the other flat surface, here the surface 61. The means 63 electrically connect the zone 60 and the zone 61 to the electrodes A and B. On the other hand, the means 63 electrically isolate the zone 60 and the zone 62 in this configuration.

The second configuration is visible in FIG. 6B and corresponds to a situation in which the radiation surface of the first configuration, namely the surface 62, is electrically connected to the reference partial area 60 to form plane 1 of FIG. whole mass. The electrical junction is located at A 'and B'.

The other flat surface 61 now plays the role of radiation surface for the antenna. The surface 61 is then electrically isolated from the zone 60.

The radiating surface is, depending on whether the first configuration is selected or the second configuration is selected, either at the front of the housing of a mobile phone in which an antenna according to the invention is placed, or at the rear of the housing .

Switching between the two configurations of the antenna is performed to optimize the connection between the phone and the base station of the mobile network to which the phone belongs. The connection with a base station of a telephony network is therefore always optimized, regardless of the position or configuration of the phone.

The planar surfaces 61 and 62 adapted to be switched to form either a part of the ground plane or the radiating surface are not located in line with the partial area 60 forming the ground plane. The flat surfaces 61 and 62 do not overlap the partial area 60.

In certain embodiments, the flat surfaces 61 and 62 may overlap the partial area 60 over a negligible area in front of their dimension, so that the general behavior of the antenna is not affected and that, depending on the switching, the antenna radiates mostly to the front or mostly to the back of the phone case. Preferably, the area of overlap of a surface 61 or 62 is less than half the area of each of said surfaces 61 or 62, preferably the area of overlap is between 20 and 0% of the area of each of said surfaces 61 or 62. As has been indicated, very preferably, there is no overlap.

The partial zone 60 of mass does not block the radiation of any flat surface whatever the chosen configuration, the partial zone 60 also plays its role of mass in the two possible configurations. Preferably, the area of the possible zone of overlap is of negligible surface compared to the size of the partial zone 60.

FIG. 7 shows another possible arrangement of the surfaces 61 and 62 as well as the zone 60. In this arrangement, the zone 60 is disposed behind a screen 3 of a telephone 5. The two flat surfaces 61 and 62 are preferentially, but not necessarily, of the same dimensions, and are located symmetrically with respect to a plane containing the zone 60 of mass reference.

In the case of FIGS. 6A, 6B and 7, the partial ground reference zone 60 is constituted by all or part of a printed circuit capable of being placed in a telephone.

Preferably, the flat surfaces 61 and 62 are metal plates.

The switching means 63 are able to form open electrical circuits or closed electrical circuits.

The means 63 comprise the junctions 81 to 86 connecting the zone 60 to the two surfaces 61 and 62.

Thus, as shown in FIG. 8, in the first configuration, the junctions 81 and 82 between the zone 60 and the surface 61 are closed circuits, while the junctions 83 and 84 between the zone 60 and the surface 62 are open circuits.

The junction 85 for connecting the point of attack 87 to the radiating surface 62 is therefore a closed circuit, while the symmetrical junction with respect to the zone 60 is an open circuit.

In the second configuration, the junctions 81 and 82 between the zone 60 and the surface 61 are open circuits, while the junctions 83 and 84 between the zone 60 and the surface 62 are closed circuits.

The junction 85 for connecting the point of attack 87 to the radiating surface 61 is therefore a closed circuit, while the junction symmetrical with respect to the zone 60 is an open circuit.

The switching means 63 may comprise at least one PIN diode.

The switching means 63 may comprise at least one active diode which is less expensive.

Preferably, the switching means 63 may comprise microelectromechanical systems MEMS technology (or "micro-electronic mechanical system" according to the English terminology generally used by those skilled in the art). The microsystems form relays for switching from one configuration of the antenna to another by alternately connecting the surfaces 61 or 62 to the zone 60.

The invention applies equally to a monobloc telephone or to a telephone comprising two shutters.

Thanks to the invention, the radiated performances of the telephone are improved, whatever the configuration or the position of use of the telephone, and this, thanks to a single antenna.

The invention is therefore compact and inexpensive.

FIGS. 9A and 9B and 10A and 10B thus show that the radiating surface is always located in the best situation, namely the rear of the housing, for better reception and better reception.

FIG. 9A thus shows that when a monobloc telephone is placed on a table, the surface 62 is the radiation surface, whereas my FIG. 9B shows that when the telephone 5 is used at the head 6 of a user, the surface 61 is the radiation surface.

FIG. 10A shows that when the flap 52 is above the flap 51, the surface 62 is the radiation surface, while FIG. 10B shows that when the flap 52 is below the flap 51, the surface 61 becomes the surface of radiation. The radiation surface is not hidden in the phone and is located at the back of the housing.

Claims (10)

1. Transmission/reception antenna comprising a ground plane (1) and at least one planar radiation surface (2), a partial ground reference zone (60), at least two planar surfaces (61, 62) extending parallel to the partial zone (60) and switching means (63) electrically linking the partial reference zone (60) to alternately one (61, 62) of the planar surfaces, thus defining a switching between a first configuration and a second configuration, the first configuration corresponding to a situation in which one (62) of the planar surfaces constitutes the radiation surface (2), the entire ground plane (1) then comprising the partial reference zone (60) and the other (61) planar surface, the second configuration corresponding for its part to a situation in which the radiation surface (62) of the first configuration is linked electrically to the partial reference zone (60) to form the entire ground plane (1), the other planar surface (61) then henceforth playing the role of radiation surface (2), characterized in that the planar surfaces overlap the partial zone (60) at most over a negligible area compared with the area of the said surfaces (61, 62).
2. Antenna according to Claim 1, characterized in that the partial ground reference zone (60) consists of all or part of a printed circuit able to be placed in a telephone (5).
3. Antenna according to one of Claims 1 or 2, characterized in that the two planar surfaces (61, 62) are of like dimensions and are situated symmetrically with respect to a plane containing the partial ground reference zone (60).
4. Antenna according to one of Claims 1 to 3, characterized in that the planar surfaces (61, 62) are metal plates.
5. Antenna according to one of Claims 1 to 4, characterized in that the switching means (63) are able to form open electrical circuits or closed electrical circuits.
6. Antenna according to Claim 5, characterized in that the switching means (63) comprise at least one PIN diode.
7. Antenna according to Claim 5, characterized in that the switching means (63) comprise at least one active diode.
8. Antenna according to Claim 5, characterized in that the switching means (63) comprise MEMS technology electromechanical microsystems.
9. Monoblock telephone (5), characterized in that it comprises an antenna according to one of the preceding claims.
10. Telephone (5) comprising two flaps (51, 52), characterized in that it comprises an antenna according to one of the preceding claims.

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