This patent application claims priority to European Provisional Patent Application No. 18382483.8, filed Jun. 29, 2018, which is incorporated herein by reference in its entirety.
The present disclosure relates to antenna modules, and more particularly, to under-roof antenna modules for vehicles.
A typical vehicle may host antennas for various wireless technologies, such as telephony (up to 4 antennas if Multiple Input Multiple Output (MIMO) antennas are used), global navigation satellite system (GNSS), Satellite Digital Audio Radio Service (SDARS), Remote Key Entry (RKE), AM/FM/Digital Audio Broadcasting (DAB) etc. The number of antennas that may possibly be hosted in a vehicle is increasing with time. Traditionally, antennas are integrated in different locations of a vehicle. Such locations may vary. Example locations include the external rear view mirror, the Shark fin, the windscreen, the bumpers, the rain sensor position, the dashboard etc.
The exterior view mirror is an external element of the car. Its available area is generally limited. Changes in the mirror design often imply an antenna redesign. As for the shark fin, this location is used mostly for telephony and GNSS. However, it is a visible location, and furthermore the available area is limited so, for instance, it is not feasible to implement a 4×4 MIMO antenna solution in the shark fin. With respect to the dashboard, it is mainly used for telephony, GNSS and RKE. However, performance of the antennas in the dashboard can be degraded if a thermal layer is used and especially for GNSS antennas because the GNSS antenna diagram pattern is pointing to the zenith (towards the GNSS satellites in the sky).
It is desirable to provide a solution for integrating various antennas at a single position of the vehicle to overcome at least some of the aforementioned issues.
In a first aspect, an under-roof antenna module for a vehicle is proposed. The under-roof antenna module comprises a metallic frame with at least one perforation, at least one transceiver, arranged at portions of the frame proximal to the at least one perforation.
An under-roof antenna module may be defined as any antenna module that may be embedded between an external curve (e.g. roof, hood, or trunk) and an internal profile of the vehicle. Thus, the antenna module may not be visible from the outside, contrary to antenna modules embedded in antenna fins, and may also not be visible from the inside of the vehicle. The metallic frame may form part of the vehicle's structure or may be attached to the vehicle's structure. In any case, the connection between the metallic frame and the vehicle's structure may be configured to maintain the electrical continuity between both elements.
A position at which the at least one transceiver is arranged with respect to the perforations has an important effect on the performance of the transceiver. By providing the at least one transceiver at portions of the frame proximal to the perforations, it is possible to maximize such performance of the at least one transceiver. Particularly, for a similar transceiver's frequency, it has been found that with a decreasing distance between the transceiver and the perforation, the Voltage Standing Wave Ratio (VSWR) may be decreased such that the Voltage Standing Wave Ratio (VSWR) is situated in a desirable range of operation values.
It is noted that the smaller the VSWR is, the better the transceiver is matched to a transmission line and more power is delivered to the receiver. The minimum VSWR is 1.0. In this case, no power is reflected from the antenna, which is ideal.
In some examples, the at least one transceiver comprises one or more terrestrial communication transceivers, such as cellular telephony antennas. In some examples the cellular telephony antennas may be configured to be operable with Long Term Evolution (LTE) frequencies.
In some examples, the under-roof antenna module may further comprise at least a second transceiver, arranged at portions of the frame distal to the perforations. In examples, the second transceiver comprises satellite antennas. In further examples, the satellite antennas are configured to be operable for receiving satellite digital audio radio services (SDARS) signals and or global navigation satellite system (GNSS) signals.
By providing the at least one transceiver at portions of the frame proximal to the perforations, and the at least second transceiver, arranged at portions of the frame distal to the perforations, it is possible to increase the efficiency of the reception by providing a MIMO system which sends and receives signals using multiple transceivers.
For example, as commented above, the at least one transceiver may comprise terrestrial communication transceivers, such as cellular communication antennas, where the transceiver's diagram pattern has a maximum of radiation at lower elevations whereas the at least second transceiver may comprise satellite transceivers, e.g. GNSS antennas, where the maximum of radiation is expected to be at the zenith pointing to the sky. Thus, terrestrial communication antennas may be provided at portions of the frame proximal to the perforations or holes whereas satellite antennas may be provided at portions of the frame distal to the holes as the presence of the holes is not required
In some examples, the under-roof antenna module may be configured to be placed in a cavity or recession of a roof portion of the vehicle. This allows for seamless integration of the antenna module in the shape of the roof of the vehicle.
In some examples, the metallic frame may be integrated with the roof portion of the vehicle. Thus, no additional piece may be required, and the frame may form part of the chassis of the roof of the vehicle.
In some examples, the under-roof antenna module may further comprise a support base, attached to the frame, wherein the first and second set of antennas are arranged along the support base. The base may allow for easier placement of the antennas along the frame.
In some examples, the metallic frame may have an elongated form along a main direction and a series of perforations along the main direction. The main direction may be parallel or transversal to a direction of movement of the vehicle.
By providing the antenna module in a cavity it is possible to integrate all antennas in a single location and maximize isolation by distributing the antennas along the elongated base. Furthermore, by providing the cavity in a top part of the vehicle, the antennas may be invisible and interference with other electronic parts of the vehicle or with other devices in the interior of the vehicle may be minimized.
In some examples, the elongated metallic frame may comprise three perforations or holes distributed along the elongated form. One central perforation may be towards the center of the frame and two extreme perforations on opposite sides of the central perforation may be towards the edges of the elongated frame.
In some examples, a first cellular telephony antenna may be attached at an edge of an extreme perforation; a second cellular telephony antenna may be attached at an edge of the other extreme perforation and a third and fourth telephony antennas may be attached at a first and second edge of the central perforation, respectively.
In some examples, the under-roof antenna module may further comprise a Satellite DARS (SDARS) antenna, arranged on top of one of the first or second cellular telephony antennas. SDARS antennas have a different radiation pattern than telephony antennas (e.g. LTE MIMO antennas). SDARS antennas may demonstrate a hemispherical pattern for communication to Satellites whereas Telephony antennas may demonstrate an omnidirectional pattern for communication at lower elevation angles towards terrestrial Telephony Base Stations. Due to the antenna pattern behavior, even if the SDARS antenna is close to the telephony antenna, a high level of isolation is obtained between them.
In some examples, the under-roof antenna module may further comprise a remote keyless entry (RKE) antenna attached to another edge of one of the extreme perforations.
In some examples, the GNSS antenna may be attached to the frame in a space between one of the extreme perforations and the central perforation.
In some examples, the perforations may comprise a rectangular shape, each having a first dimension of between 95 and 200 mm along the main direction and a second dimension of between 50 mm and 110 mm in a direction perpendicular to the main direction, respectively.
Other features, advantages and details appear, by way of example only, in the following detailed description, the detailed description referring to the drawings in which:
The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses.
FIG.1A schematically illustrates a frame for an under-roof module according to an example. Frame 10 may have an elongated form and may comprise a first part 15 and a second part 20. The two parts may define two profile steps at different levels. One level may correspond to a recession level of a roof of a vehicle and the other level may correspond to the roof level of the vehicle. The elongated frame may be configured to be mounted in a cavity of the vehicle part, e.g. roof, hood (bonnet), trunk (boot) of a vehicle. The height difference between the two levels may be selected to allow for the collocation of one or more transceivers on the lower level along the frame. The first part 15 may comprise perforations or holes 15A, 15B and 15C. The perforations may be substantially rectangular.
The MIMO antennas may be operable over multiple frequency bands, including LTE (Long Term Evolution) frequencies (e.g., 5G, 4G, 3G, another LTE generation, B17 (LTE), LTE (700 MHz), etc.). In one example, the one or more MIMO antennas may include a first or primary cellular antenna and a second or secondary cellular antenna. The first cellular antenna may be configured to be operable for both receiving and transmitting communication signals within one or more cellular frequency bands (e.g., LTE, etc.). The second cellular antenna may be configured to be operable for receiving communication signals within one or more cellular frequency bands (e.g., LTE, etc.). In another example, the one or more MIMO antennas may comprise four cellular or mobile communications antennas TEL1-TEL4. Each of the antennas TEL1 to TEL4 may comprise one or more of a transmitting element (Tx) and a Receiving element (Rx). The GNSS antenna may be arranged between two of the mobile communications antennas TEL
The telephony antennas may be placed on portions of the base 202 that are near an edge or over the perforations 205A, 205B, 205C of the frame 10. The satellite antennas (e.g. the GNSS antenna) may be placed on portions of the base 202 that are over a solid part of the frame. The operating frequency band of the transceivers situated at or near and edge or over the perforations may cover e.g. from about 700 MHz to 3100 MHz. It is noted that the frequency is the number of occurrences of a repeating event per unit of time. In this respect, any wave pattern can be described in terms of sinusoidal components. The wavelength of a sinusoidal wave may be the distance over which the wave's shape repeats. In this particular example, the wavelength may be between approximately 98 mm (3100 MHz) and 430 mm (700 MHz).
The perforations may comprise a rectangular shape. Each perforation may have a first dimension of between 95 mm and 200 mm along the main direction. It is noted that the first value of the first dimension (95 mm) may be considered as 0.22×□, wherein □ is the value of the wavelength (430 mm) for a limiting lowest frequency of operation of 700 MHz of the transceivers. Similarly, the first value of the second dimension (200 mm) may be considered as 0.46×□, wherein □ is the value of the wavelength (430 mm) for the limiting lowest frequency of 700 MHz of the transceivers. It is noted that the largest dimension of an antenna placed on portions of the base that are near an edge or over the perforations is determined by the lowest operational frequency of the antenna.
Each perforation may further have a second dimension of between 50 mm and 110 mm in a direction perpendicular to the main direction, respectively. Similarly, as before, the first value of the second dimension (50 mm) may be considered as 0.11×□, wherein □ is the value of the wavelength (430 mm) for the limiting lowest frequency of 700 MHz of the transceivers. The second value of the second dimension (110 mm) may be considered 0.25×□, wherein ␣ is the value of the wavelength (430 mm) for the limiting lowest frequency of 700 MHz of the transceivers.
Preferably, the first dimension may be between 180 mm (0.42×□) and 200 mm (0.46×□) and the second dimension between 90 mm (0.20×□) and 110 mm (0.25×□). For example, for LTE telephony antennas, such dimensions may allow for the radiation pattern and corresponding antenna gain of standard sized telephony antennas to remain within desired values for various frequencies of the LTE frequency range. It is noted that, similarly as before, □ is the value of the wavelength for the limiting lowest frequency of 700 MHz of the transceivers.
It is noted that the VSWR may be between 1 and 4 for a “desirable range of operation”. Particularly, the VSWR may be above 1 and below 3 for an “optimum range of operation” of the transceiver. The VSWR may be between 3 and 4 for an “acceptable range of operation” of operation.
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Therefore, at some frequencies of the transceiver, the VSWR may still be within the “optimum range of operation”. However, at a transceiver's frequency of 700 MHz, the VSWR may be around 6. The VSWR may thus be in a “non-acceptable range of operation” for some of the frequencies.
It is thus clear that, for a similar transceiver's frequency of e.g. 700 MHz, by reducing the distance (d) between the receivers and the hole, the VS WR may also be reduced, thus improving the performance of the receiver. On the contrary, as the distance between the receiver and the hole is increased, the receiver's impedance is decreased and the VSWR value may be outside specification.
In summary, the values of the distance (d) between the receiver and the hole for a proper functioning of the receiver may be the following:
It is further noted that for a range of transceiver's frequencies between approximately between 1750 MHz and 2200 MHz and a further range of transceiver's frequencies between 2350 MHz and 3000 MHz, the VSWR may always be in an optimum range of operation independently of the distance (d).
Similarly, as before, it is noted that the VSWR may be between 1 and 4 for a “desirable range of operation”. Particularly, the VSWR may be above 1 and below 3 for an “optimum range of operation” of the transceiver. VSWR may be between 3 and 4 for an “acceptable range of operation” of operation. It is further noted that, in all the examples, the distance (d) of the receiver with respect of the hole, as hereinbefore described, may be 0 mm.
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Therefore, at a transceiver's frequency of 700 MHz, the VSWR may be around 3.3. The VSWR may thus be outside the “optimum range of operation” but within the “acceptable range of operation”.
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Therefore, at a transceiver's frequency of 700 MHz, the VSWR may be around 3.7. Again, the VSWR may be outside the “optimum range of operation” but within the “acceptable range of operation” for some of the frequencies of the transceiver.
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Therefore, at a transceiver's frequency of 700 MHz, the VSWR may be around 6. The VSWR may thus be within the “non-acceptable range of operation”.
It is thus clear that the effect of a reduction in the width (w) of the hole, for a similar receiver's frequency, is generally that the VSWR is increased such that the performance of the receiver is reduced. On the contrary, the effect of an increase in the width (w) of the hole, for a similar receiver's frequency, is generally that the VSWR is reduced such that the overall performance of the receiver is improved.
In summary, the values of the width (w) of the hole for a properly operation of the receiver may be the following:
Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and/or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples but should be determined only by a fair reading of the claims that follow. If reference signs related to drawings are placed in parentheses in a claim, they are solely for attempting to increase the intelligibility of the claim and shall not be construed as limiting the scope of the claim.
While the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from its scope. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but will include all embodiments falling within the scope thereof.
Number | Date | Country | Kind |
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18382483.8 | Jun 2018 | EP | regional |