Antenna and associated coupler for transferring antenna functionality and corresponding communication device

Abstract

The present invention relates to an antenna (A) of a communication device, comprising: a substrate (100); a feeding point (E) of the antenna and a first ground point (GND#1) intended to be connected to a ground plane; a metallic antenna element pattern (101) printed on one side (102) of the substrate, the antenna element pattern (101) forming an open loop from the feeding point (E) to the first ground point (GND#1), the loop defining a non-metallic area (103) at its center; the antenna (A) being adapted to operate alone to radiate a radio signal, or in association with a coupler (C), the coupler (C) being arranged facing and distanced from the antenna (A) in such a way as to pick up the signal radiated by the antenna (A), the coupler (C) comprising a metallic area (203) complementary to the non-metallic area (103) facing it.

Description

TECHNICAL FIELD

[0001] The present invention relates to an antenna and to an associated coupler for transferring the antenna function in a passive manner. It also relates to a communication device comprising such an antenna capable of operating with such a coupler. BACKGROUND

[0002] Radio devices generally comprise an internal antenna, usually fully integrated into the device, and a connection to an external antenna, to enable switching from one antenna to the other depending on the operating conditions, for example when the reception conditions through the radio antenna are poor.

[0003] To this end, such a device comprises two independent radio channels, each connected to the internal antenna or to the connection to the external antenna. To switch from one channel to the other, a radio frequency or mechanical switch is used.

[0004] The use of these types of switches is not satisfactory.

[0005] In particular, radio frequency switches require a mechanism for detecting the presence of the external connection, which can prove to be expensive, bulky and detrimental to the radio performance by adding more attenuation. This detection system also poses problems of power consumption, particularly important for battery-powered devices.

[0006] In addition, as in the case of radio frequency switches, the incorporation of additional non-linear elements is a possible cause of undesirable transmission or noise.

[0007] The use of mechanical switches is bulky and expensive, and difficult to incorporate into printed circuit boards. The main functional drawback of this solution is the mechanical clatter that occurs in the event of incorrect clamping of the antenna or coaxial cable. In addition, the radio path necessarily involves the switch, which causes additional attenuation in performance.

[0008] Furthermore, the detection system is not very reliable and often produces false measurements, which leads to immediate loss of communication. SUMMARY

[0009] The present invention allows to solve at least one of the drawbacks as described above.

[0010] To this end, the invention according to a first aspect relates to an antenna of a communication device, comprising: a substrate; a feed point of the antenna and a first ground point intended to be connected to a ground plane; a pattern of metallic antenna elements printed on one side of the substrate, the pattern of antenna elements forming an open loop from the feed point to the first ground point, the loop defining a non-metallic area in its center; the antenna being adapted to operate alone to radiate a radio signal, or in association with a coupler, the coupler being arranged facing and distanced from the antenna in such a way as to pick up the signal radiated by the antenna, the coupler comprising a metallic area complementary to the non-metallic area facing it.

[0011] According to a first aspect, the application is advantageously completed, alone or in any combination of their technically possible combinations, with the following characteristics:

[0012] - the antenna element pattern comprises, from the feed point, a first metal whole pattern consisting of two longitudinal branches distanced from each other, a transversal branch connecting the two longitudinal branches, the first longitudinal branch extending from the feed point, the second longitudinal branch extending from the transversal branch parallel to the first branch, the antenna element pattern comprising a second whole pattern extending from the first ground point and comprising a transversal branch parallel and distanced from the transversal branch of the first whole pattern, the transversal branch of the second whole pattern ending at a distance of about 1 to 3 mm from the second longitudinal branch of the first pattern without contacting it.

[0013] - the non-metallic area is rectangular.

[0014] - the antenna comprises a second ground point intended to be connected to the ground plane and comprising a third whole pattern extending from the second ground point.

[0015] - the first, second and third patterns are configured to operate in the frequency bands LTE 20 and 8.

[0016] According to a second aspect, the application relates to a coupler of a communication device, the coupler comprising a rectangular substrate comprising a coupling pattern printed on one side, the coupling pattern comprising a metallic area complementary to a non-metallic area of an antenna intended to face and be distanced from the antenna of the coupler in such a way that the coupler picks up the signal radiated by the antenna.

[0017] According to a third aspect, the application relates to a communication device comprising a first housing for housing an antenna according to the first aspect of the application and a second housing for housing a coupler according to the second aspect of the application, the first housing and the second housing being configured relative to each other in such a way that the antenna and the coupler can face each other, the metallic area of the coupler then facing the non-metallic area of the antenna, the device comprising two operating modes: a first operating mode comprising the antenna operating independently for radiating a radio signal; a second operating mode comprising the antenna and the coupler for transferring the radio signal radiated by the antenna to an external antenna adapted to be connected to the coupler.

[0018] According to a third aspect, the application is advantageously completed, alone or in any combination of their technically possible combinations, with the following characteristics:

[0019] - the second housing is adapted to hold the coupler, the coupler facing the antenna and being distanced from the antenna between 1 and 3 mm.

[0020] - the coupler comprises a connector connected to the coupling pattern, which is suitable for being connected to the external antenna by means of a cable.

[0021] - the antenna is embedded in the cover, and wherein the housing for the coupler is a recess formed in the cover, the coupler being removable.

[0022] The invention has several advantages.

[0023] The coupler and the antenna are not in contact, so that it is not necessary to add any additional connection element. This is particularly advantageous when the communication device is a smart water meter for which water tightness is expected to comply with IP67 protection.

[0024] Thus, the internal antenna behaves as a conventional antenna when it is used alone, and, when the coupler is positioned facing the antenna and without having to change the radio path, allows the transmission of the signal by transmitting it to the coupler. The presence of the coupler close to the antenna makes the latter operate as a coupler. Thus, the useful signal is no longer radiated directly by the antenna, but is transmitted to the remote external antenna by the adjacent coupler.

[0025] The coupler and the antenna are not in direct contact, which allows electrical isolation between the two (useful in the case of an electricity meter). Moreover, the change from one mode of operation to another does not require any electronic or software action: the presence of the coupler makes it possible to change from a mode involving the internal antenna radiation to a mode involving coupling to an external antenna. BRIEF DESCRIPTION OF DRAWINGS

[0026] Other characteristics, objects and advantages of the invention will become apparent from the following description, purely illustrative and non-limiting, and which must be read in conjunction with the attached drawings, on which:

[0027] - Figure 1a , Figure 1b , Figure 1c , Figure 1d and Figure 1e several views of a communication device according to the invention are shown;

[0028] - Figure 2 an antenna according to the invention is shown;

[0029] - Figure 3 a coupler according to the invention is shown;

[0030] - Figure 4 a side view of a communication device according to the invention comprising an antenna and a coupler facing it is shown.

[0031] In all the figures, similar elements have the same reference. DETAILED DESCRIPTION

[0032] Figure 1a 、 1b Figures 1c, 1d, 1e show several views of the communication device D comprising a housing 1 which houses an electronic card 6 and electronic devices (not visible). The housing 1 comprises a bottom 11 and four walls 12 (two are visible in the figures) rising from the bottom 11. The housing 1 defines a volume which houses the electronic devices. An antenna A, so-called internal antenna, is connected to the electronic card 6 and allows the communication device D to transmit and receive signals. As will be further seen, the internal antenna A takes the form of a plate of overall rectangular shape. The electronic card 6 provides all the radio processing required for the communication.

[0033] Such a communication device D is for example a water meter which has to remotely acquire periodic readings. More generally, it should be noted that the present application is applicable to all communication devices.

[0034] In order to facilitate the communication, the internal antenna A protrudes from the housing 1 and is protected by a lid 2 which comprises a shell for the internal antenna A and which closes the housing 1. The lid 2 comprises a main wall 21 which makes it possible to close the housing 1 while being parallel to the bottom 11 and a secondary wall 22 which protrudes from the main wall 21, the internal antenna A being housed within the secondary wall 22. The secondary wall 22 thus has a sufficient thickness to house the internal antenna 1.

[0035] As shown in figures Figure 1b 、 1d and 1d, the communication device with the assembled lid 2 and housing 1 does not allow the internal antenna A to be seen.

[0036] In addition, a cover 5 is fixed to the lid 2 by clips in order to protect the entire structure as shown in figure Figure 1a .

[0037] The housing 1, the lid 2 and the cover 5 are preferably made of plastic. According to the application, the housing is filled with a waterproof protective gel in order to protect the electronic devices housed therein. This is because the communication device can be used as a smart water meter and has to be waterproof.

[0038] The lid 2 comprises a secondary wall 23 facing away from the secondary wall 22. The secondary wall 22 and the secondary wall 23 together define a recess 24 which makes it possible to house a coupler C which takes the form of a plate of overall rectangular shape. Such a coupler C is removable and is placed in the recess 24 facing the internal antenna A. The recess 24 also comprises elements for retaining the coupler C facing the internal antenna A. The coupler C is for example equipped with a coaxial connector 3 to which a coaxial cable 4 can be connected. An external antenna Aext is connected to the end of the coaxial cable. In order to connect the coupler to the external antenna Aext, a suitable 50-ohm connector should be provided.

[0039] The dimensions of the recess 24 and of the secondary wall 22 allow the coupler C to be positioned at a distance of between 1 and 5 mm, preferably 2 mm, from the antenna A. In other words, it is a question of positioning the coupler C as close as possible to the antenna A to facilitate the coupling C of the signals radiated by the antenna A.

[0040] Moreover, the recess 24 is shaped so as to allow the coupler C to be positioned facing the antenna A with precision, so that the coupling is optimal and the losses are as few as possible.

[0041] Moreover, the coupler C is a passive component that does not make electrical contact with the antenna A, which makes it possible to avoid damaging the communication device D. In particular, to position the coupler C, it is simply a question of placing it in the slot 24 provided for this purpose. It is therefore not necessary to dismount it or to make contact with the electronics inside. It is therefore not modified the protection index denoted IP.

[0042] Such a communication device has two modes of operation.

[0043] The first mode comprises an antenna A operating independently, which makes it possible to radiate radio signals (see Figure 1b and 1c ) or to receive radio signals.

[0044] The second mode comprises the antenna A and the coupler C in such a way as to transfer the signals radiated by the antenna A to an external antenna (see Figure 1d and 1e ). The transmission / reception of radio signals takes place through the external antenna Aext.

[0045] In this way, it is possible to position the communication device anywhere, the transmission / reception taking place at a distance from the communication device.

[0046] The transition from one mode to the other does not require any software action or the presence of a switch. It is simply a question of positioning the coupler C in the recess 24 provided for this purpose.

[0047] Advantageously, the communication device makes it possible to operate it preferably in the frequency bands LTE 20 and 8, i.e. in the 800 MHz and 900 MHz frequency bands. These frequency bands are used in particular in the field of smart meters, for example water meters. Alternatively, it is the definition of the coupler C and of the internal antenna A that makes it possible to adjust the operating frequency bands.

[0048] Antenna A

[0049] Figure 2 An embodiment applicable to an antenna A to be incorporated into the aforementioned communication device D is illustrated in detail.

[0050] The antenna A is a printed antenna comprising a substrate 100 made of dielectric material, which comprises a feed point E of the antenna A and a first ground point GND#1 connected to a ground plane (not shown) of the antenna A. The feed point E is the input point of the radio signal that the antenna A has to radiate (in the transmission direction). The substrate 100 is of overall rectangular shape and extends along the transverse X and longitudinal Z directions.

[0051] A metallic antenna element pattern 101 is printed on one side 102 of the substrate 100. The metallic antenna element pattern 101 is for example copper and is printed using techniques well known to those skilled in the art.

[0052] The metallic antenna element pattern 101 forms an open loop from the feed point E to the first ground point GND#1, the loop defining a non-metallic area 103 in its center. The fact that the antenna element pattern 101 forms an open loop (in fact almost closed) allows the radiation of the radio signal. Moreover, since the pattern 101 is almost a closed loop, it allows the antenna to be coupled to a coupler C facing it.

[0053] The non-metallic area 102 is preferably rectangular. Other shapes can be envisaged.

[0054] The antenna A is suitable for operating alone in transmission to radiate a radio signal, or in association with a coupler C, the coupler C being placed facing and away from the antenna A in such a way as to pick up the signal radiated by the antenna A, the coupler C comprising in this respect a metallic area 203 complementary to the non-metallic area 103 facing it.

[0055] The antenna element pattern 101 has a shape suitable for the envisaged application in terms of operating frequency.

[0056] According to Figure 2 According to the embodiment shown in Fig. 1, the antenna element pattern 101 comprises, from the feed point E, a first metallic overall pattern M1 consisting of two longitudinal branches 104, 105 away from each other, a transverse branch 106 connecting the two longitudinal branches 104, 105, the first longitudinal branch 104 extending from the feed point E, the second longitudinal branch 105 extending from the transverse branch 106 parallel to the first branch 104. This first pattern M1 is mainly U-shaped. The different branches making up the first pattern M1 have different thicknesses.

[0057] A fourth branch 114 is present here in the extension of the transverse branch 106 of the U.

[0058] The second overall metallic pattern M2 extends from the first ground point GND#1 connected to the ground plane. It comprises a longitudinal branch 107 extending from the first point GND#1, which is followed by a transverse branch 108 parallel and far from the transverse branch 106 of the first overall pattern Ml, the transverse branch 108 of the second overall pattern (M2) terminating at a distance of about 1 to 3 mm from the second longitudinal branch 105 of the first pattern Ml without contacting it. In other words, the second pattern M2 makes it possible to form an open loop with the first pattern Ml and to adapt it according to the desired radiation of the antenna A.

[0059] The third metallic pattern M3 extends from the second ground point GND#2 of the antenna A and makes it possible to adjust the adaptation of the antenna A: a longitudinal branch 109 extends from the second ground point GND#2, which is followed by a transverse branch 110 parallel to the transverse branch 106 of the first pattern Ml.

[0060] Coupler

[0061] Figure 3 An embodiment of a coupler C suitable for being incorporated into the aforementioned communication device D is detailed.

[0062] The coupler C comprises a substrate 200 made of a dielectric material and comprising a coupling pattern 201 printed on one side 202. The coupling pattern 201 comprises a metallic area 203 complementary to the non-metallic area 103 of the antenna A intended to face and be far from the antenna A in such a way that the coupler C picks up the signal radiated by the antenna A. The metallic area 203 extends by longitudinal branches connected to the output S of the coupler C by a connector 300. The connector 300 is 50 ohm adapted.

[0063] The substrate 200 has a rectangular portion 200a from which a protrusion 200b extends, which makes it possible to connect a coaxial connector 3 of the coupler C and in particular to the output S of the coupler C. The connector 3 is placed on the side opposite to that on which the coupling pattern 201 is printed. The connector 3 itself is connected to a coaxial cable connected to the external antenna Aext.

[0064] The coupling pattern 201 thus mainly has a rectangular metallic area 203 from which branches 204, 205, 206, 207, 208, 209 extend, making it possible to adjust the adaptation of the coupler C and to provide the connection of the coupler C to the connector 3. The metallic area 203 is thus surrounded in a loop. The longitudinal branches 205, 209 are printed on the substrate to face the branches 107, 109 of the antenna A connected to the ground points GND#1, GND#2. The branches 205, 209 also make it possible to detect the signal coming from the antenna A and thus to improve the coupling.

[0065] The rectangular metal area 202, when it faces the non-metal area of the antenna A, makes it possible to pick up the signal radiated by the antenna A and to deliver it to the output S of the coupler (in transmission).

[0066] The shape of the metal area is determined by the metal area of the antenna A that must face it.

[0067] Antenna and coupler

[0068] Figure 4 The arrangement of the antenna A and the coupler C is shown. When the coupler C is positioned facing the antenna A, the ground point of the antenna faces the ground point of the coupler C (which are those of the coaxial connector). Moreover, the branch 104 of the first pattern M1 connected to the input point of the antenna A faces the branch 204 that connects the metal area 203 of the coupler C to the output point S of the coupler C. Moreover, the printed parts face each other, of course.

[0069] Thus, whether the antenna A is alone or with the coupler C, the radio path is the same.

[0070] Application

[0071] The device described above is advantageously used as a smart water meter and in particular when the location of the meter does not allow a good radio link (for example, a meter in a basement). In this case, it is essential to be able to pass the radio function to an external antenna that is positioned in such a way as to receive the radio signal.

[0072] Moreover, a device according to the application has been produced and tested. In the mode with the antenna A alone, the measurements of the reflection parameter S11 do indeed cover the expected frequency bands: LTE 20 and 8. When the antenna A operates with the coupler C, the transmission loss S21 measured is acceptable (about 3 dB).

Claims

1. A communication device (D) comprising an antenna (A), a coupler (C), a first housing for housing the antenna and a second housing for housing the coupler (C), the antenna (A) comprising: a substrate (100); a feed point (E) of the antenna and a first ground point (GND#1) intended to be connected to a ground plane; a metallic antenna element pattern (101) printed on one side (102) of the substrate, the antenna element pattern (101) forming an open loop from the feed point (E) to the first ground point (GND#1), the open loop defining a non-metallic area (103) at its center; the antenna (A) being suitable for operating alone in a first mode to radiate radio signals and in association with the coupler (C) operating in a second mode, the coupler facing the antenna (A) and being arranged at a distance from the antenna (A), the coupler (C) comprising a rectangular substrate comprising a coupling pattern (201) printed on one side, the coupling pattern (201) comprising a metallic area (203) complementary to the non-metallic area (103) of the antenna (A) intended to face and be distanced from the antenna (A) in such a way that the coupler (C) picks up the signals radiated by the antenna (A), the first housing and the second housing being configured relative to each other in such a way that the antenna and the coupler can face each other, the metallic area (203) of the coupler then facing the non-metallic area (103) of the antenna (A), the device comprising two operating modes: a first operating mode comprising the antenna (1) alone for radiating radio signals, a second operating mode comprising the antenna (A) and the coupler (C) in such a way that the signals radiated by the antenna (A) are picked up for transferring the radio signals radiated by the antenna (A) to an external antenna suitable for being connected to the coupler (C).

2. The apparatus of claim 1, wherein, the antenna element pattern (101) comprising, from the feed point (E), a first metallic whole pattern (M1) consisting of two longitudinal branches (104, 105) distanced from each other, a transverse branch (106) connecting the two longitudinal branches (104, 105), a first longitudinal branch (104) extending from the feed point (E), a second longitudinal branch (105) extending from the transverse branch (106) parallel to the first longitudinal branch (104), the antenna element pattern (101) comprising a second whole pattern (M2) extending from the first ground point (GND#1) and comprising a transverse branch (108) parallel and distanced from the transverse branch (106) of the first metallic whole pattern (M1), the transverse branch (108) of the second whole pattern (M2) ending at a distance of 1 to 3 mm from the second longitudinal branch (105) of the first metallic whole pattern (M1) without contacting it.

3. The apparatus of claim 2, wherein, The antenna comprises a second ground point (GND#2) intended to be connected to a ground plane and comprising a third overall pattern (M3) extending from the second ground point (GND#2).

4. The apparatus of claim 3, wherein, The first metal overall pattern (M1), the second overall pattern (M2) and the third overall pattern (M3) of the antenna are configured to operate in the frequency bands LTE 20 and 8.

5. The apparatus of any one of claims 1 to 4, wherein, The non-metallic area (103) of the antenna is rectangular.

6. The apparatus of claim 5, wherein, The second housing is adapted to hold the coupler (C) facing and at a distance of 1 to 3 mm from the antenna (A).

7. The apparatus of any one of claims 1 to 4, wherein, The coupler (C) comprises a connector (3) connected to the coupling pattern (201), the connector (3) being adapted to be connected to an external antenna (Aext) by means of a cable (4).

8. The apparatus of any one of claims 1 to 4, wherein, The antenna (A) is embedded in a cover, and wherein the housing for the coupler is a recess (24) formed in the cover, the coupler being removable.

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