WO2012152415A1

WO2012152415A1 - Motor vehicle with a transparent roof and transmission antenna

Info

Publication number: WO2012152415A1
Application number: PCT/EP2012/001915
Authority: WO
Inventors: Andreas Kwoczek; Frank Backwinkel
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2011-05-07
Filing date: 2012-05-04
Publication date: 2012-11-15
Also published as: DE102011100865A1

Abstract

What is described is: a vehicle (40) with a vehicle roof and a transmission antenna (41), for example for transmitting signals for communication between vehicles. The vehicle roof comprises a section (42) consisting of a transparent material. The section (42) is in this case configured in such a way that coupling-in of signals output by the transmission antenna (41) into the section (42) is suppressed.

Description

description

Motor vehicle with transparent roof and transmitting antenna

The present invention relates to vehicles, in particular motor vehicles, with at least partially transparent roof and a transmission antenna, in particular integrated in the roof or located on the roof, for example for transmitting signals for communication between vehicles.

In order to reduce the risk of accidents in traffic, efforts are underway to establish communication possibilities between vehicles, so-called Car2Car communication. By means of such communication channels, for example, vehicles can exchange data relating to acceleration, speed or steering angle, and

Driver assistance systems can then react autonomously to movements of other vehicles or even issue warning signals to drivers of the vehicles in order to avoid accidents. In addition, commercial applications of such communication channels between vehicles are conceivable.

For safety applications and traffic management, frequencies in the range of 5.9 GHz were reserved, for example in Europe from 5.875 GHz to 5.905 GHz in three

10 MHz channels, with two additional 10 MHz channels already reserved for future use. In the United States, frequencies from 5.85 GHz to 5.925 GHz are provided for this purpose. As communication technology here is provided a WiFi communication according to the standard IEEE 802.11 a, modified to take into account the moving communication partners, i. vehicles, according to the IEEE standard

802.1 1p. According to the above-mentioned standards, the maximum radiated power is also specified.

Antennas for emitting corresponding signals are typically mounted in a rear area of the vehicle roof. Since vehicles located close to one another are typically at least approximately in the same horizontal plane, in particular the emission characteristic in such a horizontal plane is important and should allow the greatest possible range.

In particular, when the antenna is located on or on a rear part of the roof, the roof can in principle influence the emission characteristics in particular forward.

CONFIRMATION COPY It should be noted that in today's vehicles, especially motor vehicles, not only pure metal roofs are used, but roofs can often consist, for example, in an area of a sliding roof or over a larger area of glass or other transparent material.

It is therefore an object of the present invention to provide vehicles with a transmitting antenna and an at least partially transparent roof, in which an influence of the roof on a range of the transmitting antenna is at least reduced.

This object is achieved by a vehicle according to claim 1. The dependent claims define further embodiments.

According to the invention, a vehicle is provided, comprising:

a vehicle roof, wherein the vehicle roof comprises a section of transparent material, and

a transmitting antenna mounted on the vehicle,

wherein the portion of transparent material is configured such that coupling of signals emanating from the transmitting antenna is suppressed in the section of transparent material.

In this regard, it has been found that in conventional glass made transparent sections emitted by a transmitting antenna signals, such as signals for communication between vehicles, according to a waveguide in the section of transparent material can couple and thus in the direction of the section of transparent material, a reduction of the effective Transmission power occurs. Due to the configuration of the section such that a coupling of the radiation is suppressed, this effect can be avoided.

In one embodiment, the vehicle also comprises a transmitting device coupled to the transmitting antenna, in particular for transmitting signals for communication between vehicles. The signals may in particular have a frequency> 1 GHz,

For example,> 5GHz. In this frequency range is a coupling in

conventional glass particularly critical.

It should be noted that the transmitting antenna can simultaneously serve as a receiving antenna and the transmitting device simultaneously as a receiving device. However, it is also possible to provide an additional receiving antenna and / or an additional receiving device. In other embodiments, only transmission of signals is possible. In order to design the section of transparent material such that the coupling of radiation is suppressed, the section of transparent material may have a coating, in particular a coating on an upper side, ie an outer side of the vehicle. The coating may preferably be of metallic material, so that the coupling effect is avoided by the skin effect, but it is also a coating with semiconducting layers or with a resistance coating, ie. a conductive layer having a higher resistance than a metallic layer possible. Other conductive layers are possible.

In other embodiments, the transparent material is in terms of its

Calculation index selected so that the coupling of signals is suppressed.

In a further embodiment, the portion of transparent material comprises one or more conductive intermediate layers.

In another embodiment, a thickness of the portion of transparent material is selected such that the coupling is suppressed.

In a further embodiment, the portion of transparent material is arranged to suppress the Einkoppeins such that in the section passing signals experience no total reflection in this.

In particular, the transmit antenna may be in or at a rear of the vehicle roof, i. be attached to a rear of the vehicle-facing area, for example, on the vehicle roof.

Of course, a corresponding vehicle roof may also comprise a plurality of sections of transparent material, which are designed in such a way that coupling in of signals emanating from the transmitting antenna is suppressed.

The invention will be explained in more detail by means of embodiments with reference to the accompanying drawings. Show it:

1 is a diagram illustrating a radiation characteristic of a transmitting antenna in a metal roof,

2 shows a diagram for illustrating a radiation characteristic of a transmitting antenna in the case of a roof, which partially consists of glass, Fig. 3 is a diagram for illustrating the reason for different ones

Emission characteristics in Fig. 1 and Fig. 2,

4 shows a vehicle according to an exemplary embodiment,

5 shows a transparent section according to an exemplary embodiment,

Fig. 6 shows a transparent portion according to another embodiment, and

Figs. 7 to 9 show examples of different usable in embodiments of the invention

Antennas.

In the following, embodiments of the present invention will be explained in more detail. For this purpose, first with reference to FIGS. 1 to 3 fundamentals for understanding the

Invention explained before then with reference to FIGS. 4 to 9, the actual

Embodiments will be explained.

In Fig. 1 and 2 measurements are shown, which in the context of the development of

present invention and which shows a dependence of a transmission power on a direction angle of a radiated transmission power of a transmitting antenna, which is mounted on a roof, for different types of roofs.

In Fig. 1, the diagram for a metal roof 10 with roof rail 11 is shown. Arrows 13 designate a "forward direction," i.e., a direction toward a front of a vehicle with a corresponding roof At a point 12 of the metal roof 10 is a

Transmitter antenna attached, which signals in a frequency range, which a

Frequency range corresponds to a vehicle communication radiates. The point 12 is at the same time the center of rotation of the measurement, i. the radiated transmission power was recorded in a circle around the point 12 around.

On the left side of FIG. 1, the transmission power is plotted in dB as a function of angle, where 0 ° corresponds to the forward direction, and curve 14 shows the result for a collinear antenna, as will be explained later with reference to FIG. 7. a curve 15 shows the result for a monopole antenna, as will be explained later with reference to Fig. 8, and a curve 16 shows a measurement for a glass antenna, as will be explained later with reference to Fig. 9. As can be seen, in the forward direction, that is to say in the direction in which the radiation travels the longest over the roof, no or at most a very small decrease in the radiated power is noticeable. It should also be noted that the behavior is essentially independent of the antenna used. In Fig. 2, a corresponding measurement for a roof 20 is shown with a roof rail 21, which has a portion 22 which is made of glass. A point 23 indicates a point at which a transmitting antenna has been attached and around which the measurement has been taken, similar to the point 12 of FIG. 1.

Arrows 24 in turn indicate a forward direction of a corresponding vehicle with the roof 20.

A curve 25 shows a measurement for a monopole antenna, a curve 26 shows a measurement for a collinear antenna and a curve 27 shows a measurement for a disk-shaped antenna, according to the measurements of FIG. 1. As can be clearly seen, FIG

radiated transmission power in the forward direction within an angular range of about ± 20 ° significantly attenuated, in the order of -15dB. Significant deviations between the measurements of FIG. 1 and the measurements of FIG. 2 are to be found in an angular range of ± 60 ° about the forward direction, which corresponds approximately to a range in which signals emanating from the point 23 on the portion 22 of glass to meet. This leads to the realization that through a glass roof or through a roof, which has sections of glass, the effectively radiated transmission power is reduced.

It should be noted that the forward weakening discussed with reference to FIG. 2 does not occur when section 22 is removed, that is, replaced by air.

It should also be noted that similar phenomena not only in the consideration of the

Direction angle as in Figs. 1 and 2 occurs (azimuth), but also when viewing the elevation angle (elevation).

An explanation for this phenomenon is shown schematically in FIG.

At 30 in Fig. 3, a transparent portion of a roof, in particular of glass, for example, the portion 22 of FIG. 2, referred to. Signals 31 coming from a transmitting antenna impinge on the section 30 at an angle 32, in the present case approx. 88 °. For the representation, 1 was assumed as the refractive index and the relative dielectric constant of air, while for the section 30 a relative dielectric constant of 7 and a refractive index of 2.646 was assumed, which corresponds to typical values for glass. Under these circumstances, the incident beam 31 is broken into the section 30 at an angle 34 of approximately 22.2 ° to the normal. Accordingly, an angle 33 corresponds to 67.8 °, which for the selected refractive index values is equal to the angle of the internal

Total reflection is. The portion 30 thus acts as a waveguide, and as shown by the arrows 35, the incident signals can not leave the portion 30 at first, and then at the end of the portion 30, e.g. radiated upward and are thus lost in the horizontal plane.

It should be noted that a relatively large angle of incidence near 90 ° such as the angle 32 are typical for situations in vehicles, since transmitting antennas are typically mounted in a rear area of a roof and at most slightly rise from the roof, so radiation radiated under well can meet such an angle to transparent portions of the roof.

According to the invention, it is therefore proposed to design one or more transparent sections in a roof of a vehicle in such a way that coupling-in of radiation as shown by way of example in FIG. 3 is suppressed. This will be explained below with reference to

Embodiments explained in more detail.

4, an embodiment of a vehicle 40 according to the invention is shown. The vehicle 40 has in a rear area of its roof a transmitting antenna 41, which in particular for transmitting signals with frequencies greater than 1 GHz, for example signals for communication with one or more other vehicles in the range greater than 5 GHz, for example based on the Initially explained standards, is set up. The transmitting antenna 41 can also serve as a receiving antenna and can be mounted together with other antennas, for example, in a receptacle or a rack in the rear of the roof. The transmitting antenna 41 may be connected via a connection 43, for example a cable connection or a wireless connection

Transmitter 44, for example, a transmitting / receiving device (transceiver) to be connected, wherein the transmitting device 44 for generating corresponding electrical signals which are to be transmitted via the transmitting antenna 41, is set up. The

Transmitting device 44 may be connected, for example via a bus system with other vehicle components not shown.

In addition, the vehicle 40 has a transparent section 42 in its roof. The transparent portion 42 is configured in the vehicle 40 such that coupling of signals emanating from the transmitting antenna 41 into the transparent portion 42, for example, coupling as explained with reference to FIG. 3, is suppressed. Specific embodiments thereof will be explained later with reference to FIGS. 5 and 6.

It should be noted that transparent portions in a roof, such as the transparent AD cut 42, may take on various shapes and sizes. While in the embodiment of Fig. 4, the transparent portion 42 includes a major part of the roof surface, in another embodiment, a transparent portion may be arranged only in the region of a sliding roof and be arranged so that it can be retracted to open the sunroof in the roof. Also, more than one transparent section is possible.

FIG. 5 shows an exemplary embodiment of a transparent section 53 which can be used, for example, as a transparent section 42 of FIG. 4. The transparent portion 53 comprises a transparent substrate 50, for example, conventional glass used for transparent portions in vehicle roofs, and one on an upper side, i. The coating 51 is transparent in the embodiment of Fig. 5 and may be in particular a conductive, such as a metallic coating. The coating 51 prevents the coupling of radiation 52, which from a corresponding transmitting antenna as the antenna 41 of FIG. 4 emitted radiation in the transparent portion 53. In a metallic coating, this is done for example by the so-called skin effect. Other possible coatings include semiconducting doped accordingly

Coatings or other conductive coatings which are transparent and have limited resistance. In this case, the resistance is preferably kept as low as possible in order to keep losses small.

It should be noted that while in Fig. 5, the coating 51 is mounted on an upper surface of the substrate 50, the location and arrangement of the coating 51 in

Depending on the positioning of a corresponding transmitting antenna can be selected to ensure that emitted from the transmitting antenna radiation on the

Coating 51 meets. In other embodiments, if a coupling is critical only in a certain area of the substrate 50, for example based on the angle of incidence, a coating may also be provided only in such an area.

In other embodiments, conductive intermediate layers can be incorporated within a carrier material, for example made of glass. As a result, an effective glass thickness can be reduced. It has been shown that with sufficiently thin

Glass layers of the effect described above does not occur or only reduced. Accordingly, a correspondingly thin material layer can be selected even with appropriate material stability.

Another embodiment of a transparent section 60 according to the invention is shown in FIG. In this case, the transparent section 60 is made of a transparent material, which is selected such that the refractive index of the transparent material does not enable coupling in of radiation 61, which comes from the transmitting antenna.

In particular, the refractive index may be chosen such that even when refracted into the transparent material 60, there is no total reflection, i. the radiation leaves the transparent section again, as indicated by a dashed line 62.

In yet another embodiment, the transparent portion may be modified to operate as a leak source conductor, i. the coupling is suppressed by the fact that the light entering the transparent section can leave it again.

It should be noted that the invention is not limited to the arrangement of a transmitting antenna such as the transmitting antenna 41 in a rear part of the roof, but the antenna can be arranged substantially arbitrarily.

As transmitting and / or receiving antennas different types of antennas can serve. Examples of these are shown in FIGS. 7 to 9. FIG. 7 shows a collinear antenna 70, FIG. 8 shows a monopole antenna 80 and FIG. 9 shows a disk-shaped antenna 90

However, antenna types are to be understood as exemplary only, and embodiments of the present invention may be employed with any suitable type of antenna. In particular, preference is given to using antennas which, like the antennas of FIGS. 7 to 9, can emit or receive vertically polarized radiation, particularly preferably radiate or receive radiation predominantly or largely with vertical polarization.

Claims

claims

1 . Vehicle (40) comprising:

a vehicle roof, the vehicle roof having a portion (42) of transparent

Material includes and

a transmitting antenna (41) mounted on the vehicle (4), characterized in that the section (42) of transparent material has a coating (51) on at least one side of the vehicle at least in a partial area or at least in a partial area a conductive intermediate layer wherein the coating (51) or the conductive intermediate layer is designed in such a way that an injection of signals originating from the transmitting antenna (41) into the section (42) of transparent material is suppressed.

2. vehicle (40) according to claim 1,

characterized,

in that the transmitting antenna (41) is attached to an area of the vehicle roof which is closer to a rear of the vehicle than to a front of the vehicle.

3. vehicle (40) according to claim 1 or 2,

marked by

a transmitting device (44) coupled to the transmitting antenna (41).

4. vehicle (40) according to claim 3,

characterized,

in that the transmitting device (44) is designed to transmit the signals with a frequency greater than 1 GHz via the transmitting antenna (41).

5. Apparatus according to claim 3 or 4,

characterized,

in that the transmitting device (44) is designed to transmit signals for communication between vehicles via the transmitting antenna (1).

6. vehicle (40) according to any one of claims 1 -5,

characterized,

the coating (51) is selected from the group comprising a conductive one Coating, a metallic coating, a semiconductor coating and a resistive coating.

7. Device according to one of claims 1 -6,

characterized,

that the transparent material is chosen such that it has a refractive index, so that the coupling is suppressed.

8. vehicle (40) according to any one of claims 1 -7,

characterized,

in that the section of transparent material has at least one conductive intermediate layer.

9. Vehicle according to one of claims 1-8,

characterized,

that a thickness of the portion of transparent material is chosen so thin that a coupling is suppressed.

10. vehicle (40) according to any one of claims 1 -9,

characterized,

in that the section of transparent material is designed in such a way that signals entering the transparent material do not occur in the transparent material

Total reflection learned.