TECHNICAL FIELD OF THE INVENTION
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The invention pertains to the field of telecommunication, and specifically the field of telecommunication for automotive vehicles.
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More precisely, the invention relates to an electronic telecommunication device.
BACKGROUND INFORMATION AND PRIOR ART
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Some automotive vehicles comprise telecommunication devices for communicating with other vehicles, receiving position-related data or acceding to the internet. The number of telecommunication applications available for an automotive vehicle increasing with time, the number of antennas to place in a same device is becoming important. For instance, a same telecommunication device may host a Global Navigation Satellite System (GNSS), a Satellite Digital Audio Radio Service (SOARS), a wifi module, a Bluetooth module, etc.
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When two antennas operate at a same frequency band (or at two overlapping frequency bands), there is a risk of coupling between the two antennas, which is detrimental to antennas performance.
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Consequently, there is a need to have a high number of antennas in a telecommunication device, without compromising the performance.
SUMMARY OF THE INVENTION
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Therefore, one object of the invention is to provide a telecommunication device in which the coupling between the antennas is as reduced as possible.
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According to an aspect of the invention, it is provided an electronic telecommunication device comprising a casing enclosing a electronic circuit board on which are connected a first antenna via a first feed terminal and a second antenna via a second feed terminal, the first antenna being configured to operate at a first frequency band and the second antenna being configured to operate at a second frequency band overlapping at least partially the first frequency band, wherein the first feed terminal and the second feed terminal are configured so that the respective currents flowing through them are orthogonal to each other.
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The orthogonal position of the feed terminals significantly reduces the coupling between the two antennas. The proximity of two antennas having orthogonal feed terminals has less impact on the coupling and more antennas may be placed in a same delimited space.
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According to an embodiment, the first antenna is further connected to the electronic circuit board through a ground terminal, a distance between the first feed terminal and the second feed terminal being higher than a distance between the ground terminal and the second feed terminal.
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According to an embodiment, at least a third antenna is configured to operate at a third determined frequency band distinct from the first frequency band and from the second frequency band, the antennas being positioned on the electronic circuit board so that a distance between the geometrical centre of the first antenna and the geometrical centre of the second antenna is higher that a distance between the geometrical centre of the first antenna and the geometrical centre of the third antenna and higher that a distance between the geometrical centre of the second antenna and the geometrical centre of the third antenna.
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According to an embodiment, the third antenna is located between the first antenna and the second antenna.
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According to an embodiment, a distance between the first feed terminal and the second feed terminal is selected to obtain a coupling lower than -10 dB between the first antenna and the second antenna.
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According to an embodiment, a distance between the first feed terminal and the second feed terminal is selected to obtain a coupling lower than -14dB between the first antenna and the second antenna.
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According to an embodiment, at least one of the first antenna and second antenna is connected to a feed terminal located on an edge area of the electronic circuit board, the antenna extending outwards from the electronic circuit board.
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According to an embodiment, the electronic circuit board has a maximal length of 316 millimetres and a maximal width of 69,4 millimetres.
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According to an embodiment, the antennas are Planar Inverted F Antenna (known as "PIFA antennas").
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According to an embodiment, a daughter electronic circuit board is attached to the electronic circuit board, at least one antenna being placed on the daughter electronic circuit board at distance from the electronic circuit board.
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According to an embodiment, the telecommunication device is a telematic control unit intended to be placed in the roof area of an automotive vehicle.
DETAILED DESCRIPTION OF EXAMPLE(S)
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The following description with reference to the accompanying drawings will make it clear what the invention consists of and how it can be achieved. The invention is not limited to the embodiment/s illustrated in the drawings. Accordingly, it should be understood that where features mentioned in the claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims.
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In the accompanying drawings:
- Figure 1 is a schematic view of a telecommunication system involving an automotive vehicle equipped with a telecommunication device according to the invention,
- Figure 2 is a schematic view of the telecommunication device.
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The telecommunication system CS as shown in figure 1 comprises an automotive vehicle VC, here a car, equipped with a telecommunication device 1 according to an embodiment of the invention, here located on the roof of the automotive vehicle VC. The electronic telecommunication device 1 of this example is a Telematic Control Unit configured to establish wireless communication links with distant networks or devices, for instance a navigation satellite from which the electronic telecommunication device 1 may receive positioning and navigation data, a cellular network, other automotive vehicles, etc.
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The electronic telecommunication device 1 according to this embodiment is shown in figure 2. The electronic telecommunication device 1 comprises a casing, only a lower portion 2 of which is visible on figure 2. The term lower is, in this context, relative to the position of the electronic telecommunication device 1 in the vehicle VC. Here, the electronic telecommunication device 1 is located in the roof area of the automotive vehicle VC, and the lower portion is the portion of the casing which is the closest to the floor of the automotive vehicle 1.
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The casing is configured to enclose an electronic circuit board 3, here placed against the lower portion 2 of the casing. The electronic circuit board 3 comprised a main electronic circuit board 31 and a daughter electronic circuit board 32. The main electronic circuit board 31 is placed against the lower portion 2 and the daughter electronic circuit board 32 is placed at distance from the lower portion 2 and from the main electronic circuit board 31 so as not to affect the performance of other antennas.
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The main electronic circuit board 31 and the daughter electronic circuit board 32 have a rectangular shape. Both have a width lower or equal to 70 millimeters, for instance 69.40 millimeters and the electronic circuit board 3 has a total length lower or equal to 320 millimeters, for instance 316 millimeters. The thickness of the electronic telecommunication device 1 (the dimension measured in a direction orthogonal to the surface of the electronic circuit board) is lower or equal to 35 millimeters, for instance 34.63 millimeters.
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The electronic circuit board 3 comprises a plurality of antennas and their corresponding electronic circuits. Here, the plurality of antennas comprises ten antennas, among which
- a first full band cellular antenna 4 and a second full band cellular antenna 5;
- a first high band cellular antenna 6 and a second high band cellular antenna 7;
- one V2X (vehicle-to-everything) antenna 8,
- one wifi antenna 9;
- one UWB/BLE antenna 10 for ultrawide band (UWB) functions and bluetooth (BLE) functions;
- a first GNSS (global navigation satellite system) antenna 11 and a second GNSS antenna 12;
- a SOARS (Satellite Digital Audio Radio Service) antenna 13.
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The full band cellular antennas 4, 5, the high band cellular antennas 6, 7, the V2X antenna 8, the wifi antenna 9, the UWB/BLE antenna 10 are Planar inverted-F Antennas (PIFA antennas), which present good performance and low dimensions. The SDARS antenna 13 is placed on the daughter electronic circuit board 32 and the other antennas are placed on the main electronic circuit board 31.
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At least some antennas of the plurality of antennas operate at a same frequency band or at overlapping frequency bands. The electronic telecommunication device 1 according to the invention provides an advantageous arrangement of the antennas on the electronic circuit board 3, which reduces coupling between antennas sharing a same frequency band.
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Here, the two full band cellular antennas 4, 5 are configured to operate at low, medium and high frequencies, for instance frequencies comprised between 617 MHz and 5000 MHz. For instance, the two full band cellular antennas 4, 5 are configured to operate in either of the following frequency bands: [617 MHz;1427 MHz], [1427 MHz; 1517 MHz], [1695 MHz; 2700 MHz], [3300 MHz, 5000 MHz]. The first full band cellular antenna 4 is connected to the electronic circuit board 3 through a first feed terminal (or input terminal) 14 and through a first ground terminal 16. The second full band cellular antenna 5 is connected to the electronic circuit board through a second feed terminal 15 and a second ground terminal 17.
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The two high band cellular antennas 6, 7 are configured to operate at high frequencies, for instance frequencies comprised between 1427 MHz and 5000 MHz. For instance, the two high band cellular antennas are configured to operate in either of the following frequency bands: [1427 MHz; 1517 MHz], [1695 MHz; 2700 MHz], [3300 MHz, 5000 MHz].
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The V2X antenna 8 is configured to operate at a frequency band comprised between 5885 MHz and 5295 MHz.
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The wifi antenna 9 is configured to operate at frequencies comprised between 2400 MHz and 5850 MHz. For instance, the wifi antenna 9 operates either at a frequency band comprised between 2400 MHz and 2480 MHz (also known as 2G wifi) , or to a frequency band comprised between 5150 MHz and 5850 MHz(also known as 5G wifi).
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The UWB/BLE antenna 10 is configured to operate at a frequency band comprised between 6000 MHz and 8500 MHz for ultra-wide band operations and in a frequency band comprised between 2400 MHz and 2483 MHz for Bluetooth operations.
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The GNSS antennas 11, 12 are configured to operate at frequencies comprised between 1164 MHz and 1606 MHz. For instance, one of the GNSS antennas is configured to operate at a frequency band comprised between 1164 MHz and 1189 MHz (Known as L1 band), and the other GNSS antenna is configured to operate in a frequency band comprised between 1559 MHz and 1606 MHz (known as L5 band, and mostly used for high precision navigation operation).
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The SOARS antenna 13 is configured to operate at a frequency band comprised between 2320 MHz and 2345 MHz.
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An electronic telecommunication device with such a large number of antennas for such small dimensions is likely to be subject to coupling phenomena between the antennas which are configured to operate at the same frequency band or overlapping frequency band. The electronic telecommunication device 1 according to the invention has a particular arrangement of antennas which minimizes coupling.
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For instance, the arrangement of the first full band cellular antenna 4 and the second full band cellular antenna 5 is selected so that the coupling between these antennas is less than -10 dB. To do so, their respective feeds (the input current flow near their respective feed terminal 14, 15) are orthogonal to each other. Here, the two full band cellular antennas 4, 5 are placed on contiguous orthogonal edges of the main electronic circuit board 31. The respective feeds of the antenna 4, 5 are oriented in a way parallel to the surface of the main electronic circuit board, orthogonally relatively to their corresponding edges and toward the outside of the main electronic circuit board.
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Furthermore, the two full band cellular antennas 4, 5 are placed away from each other on the electronic circuit board 3. For instance, the distance between their two feed terminals 14, 15 is chosen to limit the coupling. Here, the distance between the two feed terminals 14, 15 is more than 125 millimeters, for instance 129.88 millimeters.
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Moreover, the two full band cellular antennas are arranged so that the ground terminals 16, 17 are located between the feed terminals 14, 15. In other words, the distance between any one of the feed terminals 14, 15 and any one of the ground terminals 16, 17 is smaller than the distance between the two feed terminals 14, 15. The distance between the feed terminal 14 and the ground terminal 17 is more than 95 millimeters, for instance 97.99 millimeters. The distance between the feed terminal 15 and the ground terminal 16 is more than 120 millimeters, for instance 124.7 millimeters.
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The distance between the geometrical centers of the two full band cellular antennas cellular 4, 5 is also chosen so as to limit the coupling. Here, a distance higher that 130 millimeters between the geometrical centers of the two full band cellular antenna 4, 5 is obtained, for instance 132.19 millimeters. Here, the first full band cellular antenna 4 extends outwards the electronic circuit board 3 (beyond the perimeters of the electronic circuit board 3), which permits to increase the distance between the geometrical centers of the two full band cellular antennas 4, 5. Furthermore, the outward extension of the first full band cellular antenna 4 beyond the perimeters of the electronic circuit board 3 allows to reduce the reflection from the ground which affect the antenna performance.
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The arrangement of the two high band cellular antennas 6, 7 is selected so that the coupling between these antennas is less than -20dB. To do so, the two high band cellular antennas 6, 7 are placed away from each other. Here, the distance between the geometrical centers of the high band cellular antenna 6, 7 is more than 125 millimeters, for instance here 126.41 millimeters. Here, the two high band cellular antennas 6, 7 are placed on opposite edges of the main electronic circuit board 31.
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In order to optimize the distance between the antennas of the two pairs of cellular antennas (full band 4, 5 and high band 6, 7), the first high band cellular antenna 6 is placed between the two full band cellular antennas 4, 5, and the second full band cellular antenna 5 is placed between the two high band cellular antennas 6, 7. Here, the distance between the geometrical centers of the second full band cellular antenna 5 and the first high band cellular antenna 6 is more than 55 millimeters, for instance 59.08 millimeters. The distance between the geometrical centers the second full band cellular antenna 5 and the second high band cellular antenna 7 is more than 65 millimeters, for instance 68.80 millimeters. The distance between the first full band cellular antenna 4 and the second high band cellular antenna 7 is more that 185 millimeters, for instance 189.47 millimeters.
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With such an advantageous configuration, the coupling between first full band cellular antenna 4 and the other cellular antennas 5, 6, 7 is less than -10 dB. The coupling between the second full band cellular antenna 5 and the other cellular antennas 4, 6, 7 is less than -10 dB. The coupling between the first high band cellular antenna 6 and the other cellular antenna 4, 5, 7 is less than -12dB. The coupling between the second high band cellular antenna 7 and the other cellular antennas 4, 5, 6 is less than -12dB.
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The distance between the full band cellular antennas 4, 5 along with their orthogonality is an advantageous configuration to reduce the coupling between these two antennas. However, in cases where the full band cellular antenna processes low frequency signals, it could be necessary to reduce the coupling even more. Such additional reduction may be achieved by adjusting the distance between the respective feed and ground of each full band cellular antenna 4,5.
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The arrangement of the cellular antennas 4, 5, 6, 7 regarding the other antennas 8, 9, 10, 11, 12, 13 is also chosen so as to reduce the coupling.
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For instance, the second high band cellular antenna 7 and the wifi antenna 9 are located on a same edge of the main electronic circuit board, and the distance between their geometrical centers is higher than 70 millimeters, for instance 70.87 millimeters.
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The wifi antenna 9 and the UWB/BLE antenna 10 are located on a same edge of the main electronic circuit board 31, and the distance between their geometrical centers is higher than 175 millimeters, for instance 177.14 millimeters. The coupling between these two antennas 9, 10 having such configuration is less than -15 dB.
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Although the GNSS antennas 11, 12 operate at specific frequencies, they are very sensitive antennas and it is advantageous to place these antennas at a proper distance from the other antennas, even if they do not operate at a same frequency band. Here, the geometrical center of the two GNSS antennas 11, 12 (which is, in this example, a same common geometrical center) is placed at a distance higher that 40 millimeters from the geometrical center of the wifi antenna 9, for instance 44.22 millimeters, at a distance higher than 55 millimeters from the geometrical center of the second high band cellular antenna 7, for instance 55.51 millimeters, and at a distance higher than 90 millimeters from the geometrical center of the first full band cellular antenna 4, for instance 94.07 millimeters. For instance, the geometrical centers of the GNSS antennas 11, 12 are located between the geometrical centers of the high band cellular antennas 7, 8, the geometrical centers of the antennas 7, 8, 11, 12 being aligned.
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Here, the coupling between the GNSS antennas 11, 12 and the second high band cellular antenna 7 is less than or equal to -14 dB. The coupling between the GNSS antennas 11, 12 and the first full band cellular antennas 4 is less than or equal to -15 dB. The coupling between the GNSS antennas 11, 12 and the wifi antenna 9 is less than or equal to -15 dB.
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Thanks to the above-described configuration, in particular the optimal placement of the high band antenna 6 between the full band antennas 4 and 5, the length of the traces (the conductive lines on the electronic circuit board through which the signals of the antennas flow) is minimal. Therefore, the traces losses of the antennas are minimal.
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The invention is not restricted to the embodiment described in relation to figures 1 and 2. For instance, the position and the distance between the antennas may be adapted, for instance to an electronic circuit board having different shapes or dimensions. The same applies to the number and type of antennas, which may differ from those described above.