Antenna unit for vehicle

Abstract

The invention relates to an antenna unit (1) for high-frequency signals of a vehicle, comprising at least one circularly polarized antenna, a metal resonator (16) arranged on a top side (10) of the antenna unit (1), and a conductive reflector (9) arranged on a bottom side (11) of the antenna unit (1). According to the invention, the conductive reflector (9) has a meandering structure on the outer circumference (12) thereof.

Description

[0001] The invention relates to an antenna unit for a vehicle according to the preamble of claim 1 .

[0002] Antenna units or antenna modules are used in various embodiments and fields of application, in particular for receiving and transmitting high-frequency signals. In the automotive sector, such antenna units or antenna modules are often used in Global Navigation Satellite Systems (GNSS) and are therefore used for navigation, positioning vehicles and other objects, fleet management, or traffic management systems.

[0003] In vehicles, the antenna unit is typically designed as a roof antenna, mounted on the roof, integrated into the vehicle's exterior mirror, or positioned on the vehicle's dashboard. Circularly polarized antennas or patch antennas mounted in a housing are predominantly used. These circularly polarized antennas or patch antennas have a planar geometry with a metal surface serving as a resonator. The resonator, for example, a rectangular metal surface, is typically applied to an insulating dielectric ceramic substrate, which in turn is mounted on a carrier, typically a printed circuit board (PCB). Furthermore, a reflector is provided on the bottom side of the antenna unit to shield against unwanted signals.

[0004] The transmission characteristics of the antenna unit for transmitting high-frequency signals or the reception characteristics of the antenna unit for receiving high-frequency signals are influenced not only by the installation position of the antenna unit in the vehicle, but also by the size of the carrier and, therefore, also by the size of the reflector on the bottom side of the antenna unit. Due to installation restrictions in the vehicle, the smaller the carrier and, therefore, the smaller the reflector, and the less the installation position of the antenna unit in the vehicle (for example, for receiving GNSS satellites) is oriented toward the zenith or the sky, the lower the desired antenna gain of the antenna unit from above and, therefore, from the zenith or the sky, and the higher the undesired antenna gain of the antenna unit resulting from waves reflected from the ground.

[0005] The basic object of the present invention is to provide an antenna unit for a vehicle, in which the performance of the antenna unit, in particular with regard to the desired antenna gain, is increased in a simple manner.

[0006] This object is achieved by an antenna unit for a vehicle having the features of patent claim 1 .

[0007] Advantageous developments of the invention form part of the further patent claims.

[0008] According to the present invention, to improve the performance and thus the desired antenna gain of a vehicle antenna unit, particularly when the antenna unit's size is limited by installation requirements (e.g., when the antenna unit is installed in a vehicle's side mirror), the vehicle antenna unit includes a metallic conductive reflector on its underside with a specific shape or structure. To this end, the metallic conductive reflector has a meandering structure at its periphery (i.e., in its edge region), thereby creating a larger current path for the induced current flowing within the conductive reflector. This causes the induced current, which primarily flows along the edges of the conductive reflector, to follow a larger current path due to the tortuous structure and, therefore, must travel a longer distance. The conductive reflector designed according to the present invention thus has the same effect on the flow of the induced current as a significantly larger conductive reflector. Consequently, the performance of the antenna unit is also improved, resulting in a higher antenna gain. The higher antenna gain of the antenna unit is effective both when receiving high-frequency signals via the antenna unit and when transmitting high-frequency signals via the antenna unit. Preferably, a higher antenna gain of the antenna unit is also achieved when receiving high-frequency satellite signals by the antenna unit in the direction of the zenith and thus in the direction of the sky or in the direction of satellites located there.

[0009] If necessary, a contact for a ground line of the antenna of the antenna unit can also be provided on a reflector arranged on the bottom side of the antenna unit, and thus a corresponding ground connection can be achieved between the reflector and the ground line of the antenna unit.

[0010] In an advantageous refinement of the invention, the conductive reflector is designed as a metal plate. Alternatively, the conductive reflector can also be designed as a conductive plastic carrier, for example as a carrier film, which has a meandering metallization applied, for example, by means of a laser, on its circumference or in its edge region. This means that in this case, the metallization is applied to the plastic carrier, in particular to the carrier film, in the desired structure, thereby creating an injection-molded three-dimensional circuit carrier (3D molded interconnect device) with a meandering metallization.

[0011] In a conductive reflector designed as a metal plate, multiple notches or cutouts are preferably provided on the outer circumference or edge region of the metal plate to achieve a meandering structure of the conductive reflector, thereby forming strip-shaped or sheet-like metal tongues. Preferably, a large number of strip-shaped metal tongues are formed on the outer circumference of the metal plate to create the largest possible current path in the edge region of the metal plate serving as the conductive reflector. However, for stability reasons, a specific width of the strip-shaped metal tongues should not be exceeded. For example, these strip-shaped metal tongues should have a minimum width of 2 mm.

[0012] In an advantageous refinement of the present invention, the strip-shaped metal tongue in the edge region of the metal plate is bent perpendicularly to the plane of the metal plate. Preferably, the strip-shaped metal tongue in the edge region of the metal plate is bent perpendicularly to the plane of the metal plate, at least in the direction of the top side of the antenna unit. This allows for a more compact design of the antenna unit and, therefore, also minimizes the installation space required for the antenna unit in the vehicle or in corresponding vehicle components.

[0013] Alternatively, if suitable structural space is available for the antenna unit in the vehicle or a corresponding vehicle component, the strip-shaped metal tongues in the edge region of the metal plate can be bent perpendicularly to the plane of the metal plate, not only toward the top side of the antenna unit but also toward the bottom side of the antenna unit. In particular, these strip-shaped metal tongues in the edge region of the metal plate can be bent alternately perpendicularly toward the top side of the antenna unit and perpendicularly toward the bottom side of the antenna unit relative to the plane of the metal plate. This further increases the current path in the edge region of the metal plate, which serves as a conductive reflector.

[0014] In other advantageous designs of the present invention, in order to increase the current path in the edge area of ​​the metal plate serving as a conductive reflector, the end area of ​​the strip-shaped metal tongue can be bent perpendicularly toward the inner area of ​​the metal plate and thus toward the inner area of ​​the antenna unit, without having to provide a larger structural space for the antenna unit in the vehicle or in the corresponding components of the vehicle.

[0015] In particular, to receive high-frequency signals from at least one specific frequency band, in particular high-frequency satellite signals from at least one specific frequency band, the antenna unit includes at least one circularly polarized antenna. This circularly polarized antenna is preferably designed as a ceramic antenna having a ceramic substrate with a high dielectric constant. Therefore, in a preferred embodiment of the antenna unit, the antenna unit includes at least one circularly polarized ceramic antenna or patch antenna for receiving high-frequency signals from a specific frequency range, in particular high-frequency satellite signals from at least one specific frequency band. For example, two circularly polarized ceramic antennas are provided to receive high-frequency signals from two different frequency ranges or bands, in particular high-frequency signals from satellite signals in two different frequency bands. For example, if the antenna unit includes two ceramic antennas, two stacked ceramic substrates are provided to receive high-frequency signals from two different frequency bands, in particular high-frequency signals from satellite signals in two different frequency bands. The respective ceramic substrates are arranged between a carrier, preferably designed as a printed circuit board, and the metal resonator of the antenna unit. A plurality of electronic components of the antenna unit, such as signal amplifiers or evaluation circuits, are arranged on the bottom side of the carrier, which is preferably designed as a printed circuit board.

[0016] Advantageously, in the vehicle antenna unit according to the present invention, the performance of the antenna unit and, therefore, the antenna gain of the antenna unit are significantly improved in a simple manner due to the design according to the present invention of the reflector on the bottom side of the antenna unit, while maintaining the same size of the antenna unit and, therefore, the required installation space for the antenna unit. In particular, while maintaining the same installation space for the antenna unit, the performance of the antenna unit and, therefore, the antenna gain of the antenna unit are significantly improved with respect to high-frequency signals received from the zenith direction.

[0017] Furthermore, the invention also comprises combinations of features from the described embodiments.

[0018] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the accompanying drawings:

[0019] Figure 1 A view showing an antenna unit with a housing;

[0020] Figure 2 shows a side view of the antenna unit with system components of the antenna unit;

[0021] Figure 3 A schematic diagram showing a conductive reflector of an antenna unit designed as a metal plate;

[0022] Figure 4 shows a plan view of an antenna unit with system components in a first embodiment of a strip-shaped metal tongue designed as a conductive reflector of a metal plate;

[0023] Figure 5 A top view of an antenna unit with system components in an alternative embodiment of a strip-shaped metal tongue designed as a conductive reflector of a metal plate is shown;

[0024] Figure 6 A cross-sectional view of an antenna unit with system components is shown.

[0025] The exemplary embodiments described below are preferred embodiments of the present invention. In these exemplary embodiments, the components described in these embodiments each demonstrate individual, independently considered features of the present invention, each of which further improves the present invention independently of one another and can therefore also be considered as components of the present invention, either individually or in combinations other than those shown. Furthermore, the described embodiments can be supplemented by other already described features of the present invention.

[0026] In the figures, functionally identical elements are each provided with the same reference numerals.

[0027] Vehicle basis Figure 1 The antenna unit 1 shown, which is provided with a housing 2 (e.g., a plastic housing), is installed, for example, in a side-view mirror of a vehicle and secured there by means of a fastening element 4. The compact antenna unit 1 or housing 2 of the antenna unit 1 has dimensions of approximately 50 mm x 40 mm x 25 mm, for example. To connect the antenna unit 1 externally, a cable connection 3 for a high-frequency cable is led out of the plastic housing 2. The antenna unit 1 is configured, for example, as a dual-band module for receiving high-frequency satellite signals from two frequency bands of a global navigation satellite system (GNSS): satellite signals in the so-called L5 band (with a frequency range between 1164 MHz and 1218 MHz) and satellite signals in the so-called L1 band (with a frequency range between 1559 MHz and 1606 MHz). To this end, these high-frequency signals should be received by the antenna unit 1 as exclusively as possible from the zenith direction of the satellites and, therefore, from the top side 10 of the antenna unit 1, while undesired signals from the bottom side 11 of the antenna unit 1 should be suppressed as much as possible. Thus, the performance of the antenna unit 1 and the antenna gain of the antenna unit 1 are evaluated.

[0028] according to Figure 2In the side view, the antenna unit 1 has two circularly polarized ceramic antennas, the design of which is based on two stacked cuboid ceramic substrates 5 and 6, which have a high relative dielectric constant ∈r. The lower ceramic substrate 6 is arranged on a carrier 7 designed as a printed circuit board. A shielding plate 8 for electronic components applied to the printed circuit board 7 (in particular for a signal amplifier applied on the bottom side of the printed circuit board 7) is provided below the carrier 7. In addition, a conductive reflector 9, for example, designed as a metal plate, is provided on the bottom side 11 of the antenna unit 1, which serves to suppress unwanted signals from the bottom side 11 of the antenna unit 1. For this purpose, a longer current path for the induced current, which preferably flows in the edge region 12 of the conductive reflector 9 (which is designed as a metal plate), is particularly advantageous.

[0029] Especially as Figure 3 , wherein conductive reflector 9, designed as a metal plate, is shown separately and has a meandering structure at its edge region 12. Since there is very limited structural space in a vehicle's side mirror for mounting antenna unit 1, and thus the available area of ​​conductive reflector 9, designed as a metal plate, is also limited, this method allows for a longer current path in edge region 12 of conductive reflector 9, designed as a metal plate. This effectively suppresses unwanted signals from bottom side 11 of antenna unit 1 and significantly improves the performance of antenna unit 1. To extend the current path in edge region 12 of conductive reflector 9, a plurality of notches 13 are introduced into edge region 12 of conductive reflector 9, thereby forming a plurality of strip-shaped metal tongues 14 of conductive reflector 9, designed as a metal plate. These metal tongues have a length of, for example, 15 mm and a width of, for example, at least 2 mm. The strip-shaped metal tongue 14 of the conductive reflector 9 designed as a metal plate is bent through 90° and thus bent vertically upward in the direction of the top side 10 of the antenna unit 1, so that the end region 15 of the strip-shaped metal tongue 14 of the conductive reflector 9 designed as a metal plate points in the direction of the top side 10 of the antenna unit 1. This design of the strip-shaped metal tongue 14 of the conductive reflector 9 designed as a metal plate does not change the aforementioned dimensions of the antenna unit 1 or the aforementioned dimensions of the housing 2 of the antenna unit 1, and therefore, in particular does not affect the compact design of the antenna unit 1.

[0030] according to Figure 4 As shown, a metal resonant surface 16 is applied as an electrode on the top side 10 of the antenna unit 1 and thus on the ceramic surface of the upper ceramic substrate 5. Two feed points 17 for feeding energy into the antenna unit 1 are provided on the metal resonant surface 16, for example. Figure 4In an embodiment, the strip-shaped metal tongue 14 of the conductive reflector 9 designed as a metal plate is bent 90° and thereby bent vertically upward in the direction of the top side 10 of the antenna unit 1, wherein the end region 15 of the strip-shaped metal tongue 14 of the conductive reflector 9 designed as a metal plate points in the direction of the top side 10 of the antenna unit 1.

[0031] according to Figure 5 As shown in the embodiment, the strip metal tongue 14 of the conductive reflector 9 designed as a metal plate is connected to the Figure 4 Like the embodiment of FIG. 1 , the strip-shaped metal tongue 14 of the conductive reflector 9 designed as a metal plate is bent 90° and thus bent vertically upward in the direction of the top side 10 of the antenna unit 1. In contrast, the end region 15 of the strip-shaped metal tongue 14 of the conductive reflector 9 designed as a metal plate is bent again at 90° in the direction of the inner region 18 of the conductive reflector 9 designed as a metal plate, or in the direction of the inner region 18 of the antenna unit 1. Therefore, although the conductive reflector 9 designed as a metal plate is designed with a long strip-shaped metal tongue 14, the compact design of the antenna unit 1 is not affected.

[0032] according to Figure 6 To further illustrate, Figure 4 The antenna unit 1 mentioned by way of example in the exemplary embodiment of FIG. 1 is shown in a sectional view with its components or constituent parts.

[0033] As described above, the design of the vehicle antenna unit 1 according to the present invention can significantly improve the performance of the antenna unit 1 and, therefore, the antenna gain of the antenna unit 1. In the described embodiment of the vehicle antenna unit 1 for receiving high-frequency signals in the L5 frequency band between 1164 MHz and 1218 MHz and in the L1 frequency band between 1559 MHz and 1606 MHz, a significant increase in antenna gain can be achieved in the angle range representing the conical elevation angle or deviation from the zenith, as well as in the angle range representing the azimuth angle, when receiving these high-frequency signals. For example, an antenna gain of between 3 dB and 4 dB can be achieved for the vehicle antenna unit 1 in both of these angle ranges.

[0034] Overall, this example shows the manner in which an antenna unit according to the invention for receiving high-frequency signals of a vehicle can be provided.

[0035] List of Reference Numerals

[0036] 1 antenna unit

[0037] 2 shell

[0038] 3 cables

[0039] 4 fixings

[0040] 5Ceramic substrate

[0041] 6Ceramic substrate

[0042] 7. Printed Circuit Board

[0043] 8 shielding plates

[0044] 9 metal plates

[0045] 10 Top side of antenna unit

[0046] 11 Bottom side of antenna unit

[0047] 12 Edge area of ​​metal plate

[0048] 13. Notches in Sheet Metal

[0049] 14 metal tongues

[0050] 15 End area of ​​metal tongue

[0051] 16 metal resonant surface

[0052] 17 feeding points

[0053] The inner area of ​​18 antenna units.

Claims

1. An antenna unit (1) for high-frequency signals of a vehicle, comprising at least one circularly polarized antenna, a metal resonator (16) arranged on the top side (10) of the antenna unit (1), and a conductive reflector (9) arranged on the bottom side (11) of the antenna unit (1). It is characterized by: The conductive reflector (9) has a meandering structure on its outer circumference (12).

2. The antenna unit (1) according to claim 1, characterized in that The conductive reflector (9) is designed as a metal plate or a conductive plastic carrier.

3. The antenna unit (1) according to claim 2, characterized in that The metal plate (9) has a plurality of notches (13) on its outer periphery (12) for forming strip-shaped metal tongues (14).

4. The antenna unit (1) according to claim 3, characterized in that The strip-shaped metal tongue (14) is bent perpendicularly relative to the plane of the metal plate (9).

5. The antenna unit (1) according to claim 4, characterized in that The strip-shaped metal tongue (14) is bent perpendicularly relative to the plane of the metal plate (9) in the direction toward the top side (10) of the antenna unit (1).

6. The antenna unit (1) according to claim 4, characterized in that The strip-shaped metal tongue (14) is bent perpendicularly relative to the plane of the metal plate (9) in the direction of the top side (10) of the antenna unit (1) and conversely in the direction of the bottom side (11) of the antenna unit (1).

7. The antenna unit (1) according to claim 5 or 6, characterized in that The end region (15) of the strip-shaped metal tongue (14) is bent vertically toward the inner region (18) of the metal plate (9).

8. The antenna unit (1) according to claim 2, characterized in that The electrically conductive plastic carrier serving as the conductive reflector (9) has a meandering metallization layer on its outer circumference.

9. The antenna unit (1) according to any one of claims 1 to 8, characterized in that The antenna unit (1) has at least one circularly polarized antenna for receiving high-frequency signals.

10. The antenna unit (1) according to claim 9, characterized in that At least one ceramic substrate (5, 6) is arranged between the carrier (7) and the metal resonator (16).

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