EP2756550A1

EP2756550A1 - Multi-band aerial for a motor vehicle

Info

Publication number: EP2756550A1
Application number: EP12745639.0A
Authority: EP
Inventors: Andreas Kwoczek; Yuanhao WANG
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2011-09-17
Filing date: 2012-08-09
Publication date: 2014-07-23
Anticipated expiration: 2032-08-09
Also published as: CN103797643B; CN103797643A; DE102011113725A1; WO2013037445A1; EP2858176A1; EP2858176B1; EP2756550B1

Abstract

The invention relates to a multi-band aerial (1), more particularly for use in a motor vehicle, consisting of: a cone emitter (3) with a symmetrical axis (R) for mounting the cone emitter (3) by the tapering end perpendicular to a ground surface (2); a first monopole emitter (12), which is adjoined, in the direction of the symmetrical axis (R), to the cone emitter, wherein the first monopole emitter (12) is electrically connected to a side surface (9) of the cone emitter (3).

Description

description

Multi-range antenna for a motor vehicle

Technical area

The invention relates to a multi-range antenna, in particular a multi-range antenna for use in a motor vehicle, which is suitable for a car-to-car communication.

State of the art

In particular for mobile radio, several frequency bands within Europe are in

Use, for example, 890-960 MHz and 1710-1880 MHz for GSM and 1920-2170 MHz for UMTS. Therefore, multi-range antennas are required for use in motor vehicles, ie antennas which are multiband-capable. That is, the antennas used in the motor vehicle are intended to transmit and receive radio signals in different

Be suitable frequency bands.

In addition to the previously implemented frequency bands, for example for

Telecommunications services, also radio signals for digital radio and future services such as LTE, WiMAX, WiBro, WLAN and UWB are served. For example, these additional services may add another frequency range around 5.9 GHz

Transferring information between vehicles, d. H. for one

Car-to-car communication.

For all frequency ranges, it is desirable that the receive and receive

Radiation characteristic of a multi-range antenna used for all desired frequency ranges in the horizontal direction is independent and there are no shadowing by individual radiator elements in certain directions. For the

This means that the directional diagram over a high bandwidth has a good omnidirectional characteristic, ie no larger indentations, and the energy can be emitted uniformly in horizontal directions to the communication receivers. Document DE 10 2007 061 740 A1 discloses a multi-region antenna with two monopoles extending perpendicular to a plane. The monopoles have lower antenna sections which extend in a V-shape from an antenna base on the plane. One of the legs is followed by a simple monopole section aligned with a vertical plane. At the other of the thighs closes

L-shaped monopole section on.

From the document EP 1 189 305 A2 a cone antenna is known, which is embedded in a dielectric material. The cone antenna is arranged on a round plate and widens with increasing distance from the base plate.

Also from the document US 7,286,095 a cone antenna is known which is partially received in a plastic body. The cone antenna is arranged on a disc-shaped base plate, so that the cone antenna is with its tip on the base plate.

The publication US 2003/0103008 A1 shows a multi-region antenna structure in which a cone-shaped antenna section is arranged with its tip on a base plate. At the broad end of the cone-shaped antenna section is followed by a cylindrical section. Parallel to the base plate extending from the edge of the cylindrical portion antenna structures, which are aligned parallel to the base plate.

It is an object of the present invention to provide a multi-region antenna, in particular for use in a motor vehicle, which has a direction-independent omnidirectional characteristic in a plurality of frequency ranges.

Disclosure of the invention

This object is achieved by the multi-region antenna according to claim 1 and the

Multirange antenna arrangement solved according to the independent claim.

Further advantageous embodiments of the present invention are specified in the dependent claims. According to a first aspect, a multi-region antenna, in particular for use in a motor vehicle, is provided. The multirange antenna includes:

- A cone radiator with an axis of symmetry to the cone radiator with his

set up expiring end perpendicular to a ground surface; and

a first monopole radiator extending in the direction of the axis of symmetry to the

Connected cone radiator, wherein the first monopole radiator is electrically connected to a side surface of the cone radiator.

One idea of the above multigrade antenna is to prevent, by a stacking arrangement of individual radiator elements, the cone radiator (cone-shaped radiator) and the first monopole radiator, shading in certain directions occurring in a horizontal plane perpendicular to the axis of symmetry of the cone radiator. Furthermore, it is advantageous that the overall height of the multirange antenna can be reduced by the active coupling of the cone radiator with the first monopole radiator, and thus a very broadband antenna behavior can be achieved, in particular for lower frequencies. This is achieved in particular by designing a cone radiator for high frequency ranges and arranging the first monopole radiator on it. In order for the overall height of the assembly to be utilized, it is necessary that the monopole radiator be connected to a side surface of the cone radiator. In addition, in the above multigrade antenna, it is possible to provide an impedance matching for the

Radiator elements for a frequency range from 2-3GHz to be made solely by dimensioning the cone radiator. In the lower frequency range to 2-3 GHz, the

Impedanzanpassung achieved by the dimensioning of the monopole radiator.

Furthermore, the first monopole radiator can be flush with the side surface of the

Connect cone radiator. In particular, a second monopole radiator may be provided, which adjoins the cone radiator in the direction of the axis of symmetry, wherein the second monopole radiator is electrically connected to a side surface of the cone radiator.

According to a further embodiment, the second monopole radiator can be flush with the side surface of the cone radiator. In particular, the second

Monopole radiator with respect to the cone radiator the first monopole radiator

be arranged opposite.

Furthermore, the second monopole radiator can have a roof capacity, which extends in particular transversely to the axis of symmetry over the cone radiator. The multigrade antenna can be made contactable at the outgoing end of the cone radiator by an inner conductor of a coaxial cable.

Furthermore, a wider end of the cone radiator may have a conductive conical surface on which a GPS antenna is arranged, wherein the GPS antenna can be contacted by the cone radiator via a conductor insulated from the cone radiator.

A connection adapter may be provided to interconnect the inner conductor of the coaxial cable and the cone radiator.

According to a further aspect, a multirange antenna arrangement is provided with the above multigrade antenna and a ground plane, in particular a body outer surface of a motor vehicle.

Brief description of the drawings

Preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

Figure 1 is a schematic side view of a multi-region antenna;

Figure 2 is an exploded view of the multigrade antenna of Figure 1; and

Figure 3 shows an alternative embodiment of a multi-range antenna with an additional GPS antenna.

Description of embodiments

Figure 1 shows a schematic cross-sectional view of a multi-region antenna 1, which can be arranged on a ground surface 2. The ground plane 2, for example, a

Car roof or a separately provided ground surface.

On the ground plane 2, a cone radiator 3 electrically insulated from the ground plane 2 by the ground plane 2 is arranged with an electrically conductive surface, wherein the axis of symmetry R of the cone radiator 3 is arranged perpendicular to the ground plane 2. The cone radiator 3 has an expiring first end (end with smaller

Cross-sectional diameter or the end side of the cone radiator corresponding end), with which it rests on the ground surface 2, so that a second end, which has a larger diameter with respect to the axis of symmetry R of the cone radiator 3 with respect to the outgoing end, spaced from the ground surface 2 is.

The cone radiator 3 has a circular cross-section with respect to a plane parallel to the ground plane 2 and thereby has an optimal omnidirectional characteristic. Alternatively, cross-sections deviating from the circular cross-section, such as oval cross-sections, are possible to adapt to a desired omnidirectional characteristic.

The cone radiator 3 can be made entirely of a conductive material, such. As a metal, or as a coated with a metal layer plastic body.

Alternatively, the cone radiator 3 may also be formed as a hollow body.

The cone radiator 3 is electrically conductive and isolated from the ground plane 2. The ground plane 2 has a feed opening 4, through which an inner conductor 5 of a

Coaxial cable 6 is guided without electrically contacting the ground plane 2. One

Outer conductor 7 of the coaxial cable 6 (shield) is connected to the ground plane 2. The inner conductor 5 of the coaxial cable 6 is connected to the outer surface of the cone radiator 3.

For mechanical stabilization of the cone radiator 3 is a fastening ring. 8

provided, which surrounds the cone radiator 3 and supported on the ground surface 2. Thereby, the cone radiator 3 can be reliably held in the aligned position on the ground surface 2, and in particular, bending of the cone radiator 3 such that its symmetry axis R comes out of the perpendicular with respect to the ground surface 2 can be prevented.

The mounting ring 8 is preferably formed of a non-conductive, dielectric material, such as Plexiglas, plastic or the like. The cone antenna 3 is preferably connected to the mounting ring 8 at the contact surfaces between the

Outer surface of the cone radiator 3 and corresponding surfaces of the mounting ring 8 and bonded to the support surface 10 of the mounting ring 8 on the ground surface 2 or otherwise secured. The cone radiator 3 thus has a circumferentially extending, electrically conductive side surface 9 and a conical surface 1 1, which may be open or closed, electrically conductive or non-conductive.

In the illustrated embodiment, the conical surface 1 1 is executed closed and closes the wider end of the cone radiator 3. The conical surface 11 carries a first monopole emitter 12 and a second monopole emitter 13, which are each formed electrically conductive. The first monopole radiator 12 is flush with the edge of the cone surface 11 and is in the direction of the axis of symmetry R of the cone antenna 3, d. H. perpendicular to the ground plane 2, from the cone surface 11 (in a direction away from the ground plane 2). The second monopole radiator 13 is disposed substantially at an opposite portion of the edge of the conical surface 1 1 and is also perpendicular to the ground surface 2, d. H. in the same direction as the first

Monopole radiator 12, from.

The first monopole radiator 12 is designed as a straight-line conductor, while the second monopole radiator 13 has a rectilinear conductor, which is provided with a transverse conductor

Roofing capacity 14 is provided. To form the roof capacity 14 is the second

Monopole radiator 13 L-shaped with two legs 14, 15 is formed. A first leg 15 extends perpendicular to the ground surface 2 and a second leg 14 substantially parallel to the ground surface 2. wherein the first leg 14 of the L-shaped second monopole radiator 13 remote from the cone radiator 3 projects transversely in the direction of the first monopole radiator 12 over the cone surface 11 , The length of the projecting over the conical surface 11 roof capacity 14 is preferably less than the diameter of the conical surface eleventh

The length of the first monopole radiator 12 is less than the adjoining the cone radiator 3 second leg 15 of the second monopole radiator 13th

The dimensioning of the dimensions of the individual elements of the multirange antenna 1 will be discussed in more detail below. In particular, size ranges are given for the following dimensions: cone angle α than that of the side surface 9 of the

Cone angle spanned 3 radiator, radiator cone height H _c than the length of

Cone radiator 3 in the direction of its axis of symmetry R, first monopole radiator height H _u as the length of the first monopole radiator 12, second monopole radiator height H _g as the length of the second leg 15 of the second monopole radiator 13, length of the roof capacitance D, as the Length of the first leg 14 of the second monopole radiator 13, first

Monopole radiating width B _u as the width of the first monopole radiator 12 in the radial direction to the axis of symmetry R of the cone radiator 3, first monopole radiator depth T _u as the width of the first monopole radiator 12 in the tangential direction to the axis of symmetry R of

Cone radiator 3, second monopole radiator width B _g as the width of the first

Monopole radiator 12 in the radial direction to the axis of symmetry R of the cone radiator 3, second monopole radiator depth T _g as the width of the first monopole radiator 12 in the tangential direction to the symmetry axis R of the cone radiator 3 and width of the roof capacity B _g , as the width of the first monopole radiator 12 in the direction of the axis of symmetry R of the

Cone radiator 3.

The dimensioning of the cone radiator 3 depends on the input impedance, so that a broadband adaptation of the antenna to the impedance of the coaxial cable 6 can be achieved. For example, for a 50 Ω coaxial cable 6 when using an attachment ring 8 made of Plexiglas with a dielectric constant ε _Γ = 3.4, a preferred opening angle α = 48.65 ° results assuming infinite expansion of the

Cone radiator 3. By limiting the cone radiator 3 to a finite

Konusstrahlerhöhe H _c reflections are caused at the end of the cone radiator 3. As a result, standing waves are generated on the cone surface, leading to the antenna terminal to an input impedance Z _in , which is no longer purely real. The effect is

frequency dependent.

It has been found that for an attenuation of not more than -10 dB in the frequency range of 3 GHz to 9 GHz, the cone angle α between 45 ° and 66 ° and the

Cone radiator height H _{c should be} between 16 mm and 30 mm. Preferably, the Konusstrahlerhöhe H _{c should be} between 24 mm and 30 mm, while the cone angle α is preferably between 60 ° and 70 °. In particular, optimum values can be given as conical radiator height H _c 27 mm and as cone angle α 66 °.

A modern radio communication system in a motor vehicle operates in one

Frequency range from 780 MHz to 5.925 GHz and usually includes seven

different radio services. The proposed multirange antenna 1 should therefore have a bandwidth of more than 5 GHz and a corresponding omnidirectional characteristic. The following is a table showing the current radio services for a

Motor vehicle and the corresponding frequency ranges specified.

In addition, UWB (ultra wide band) services in the range of up to 10.6 GHz can also be used in the future. It can be seen from the above table that the total bandwidth that would have to be provided by the multirange antenna 1 is 5.145 GHz. To provide such a bandwidth alone with the cone radiator leads to a diameter of at least 65 mm at an opening angle of 60 °. Such a cone structure would be too large and, moreover, mechanically problematic. A reduction of

Cone radiator height also usually results in good impedance matching, but the lowest operating frequency increases to a frequency above 780 MHz.

For example, a 21.5 mm high cone radiator has a good impedance match of 2.33 GHz to 27.5 GHz at an aperture angle of 51 ° at 50Ω. However, the antenna diameter here is only 20.5 mm, which represents a significant reduction in comparison to a cone radiator of 65 mm diameter. The frequency gap in the range between 780 MHz to 2.3 GHz is now with other antenna structures, ie. H. the

Monopole radiators 12, 13, covered. By choosing the two narrowband

Monopole emitters 12, 13 can be the missing frequency ranges of the services that are located in the not covered by the cone radiator 3 frequency ranges, namely LTE low, GSM 900 and UMTS, are operated. So that the Monopolstrahler 12, 13 the

Do not disturb omnidirectional characteristics of the cone radiator 3, they are above the

Conical radiator 3 is arranged.

To further reduce the overall height of the multi-region antenna 1, the monopole radiators 12, 13 are placed in contact with the side surface 9 of the cone radiator 3, so that the cone radiator 3 and the monopole radiators 12, 13 now together as

Narrow-band monopole spotlights act. Thus, the entire Bäuhöhe the

Multi-range antenna 1 are kept low. For the missing frequency ranges, the antenna formed with the first monopole radiator 12 is dimensioned so that it has a size of λ / 4, wherein due to the coupling with the outer surface of the cone radiator 3, the effective height of the first monopole radiator height H _u and the Konusstrahlerhöhe H _c composed. At the preferred cone radiator height H _c of 27 mm then results in a first

Monopole radiator height H _u of 41.6 mm for UMTS and a second monopole radiator height H _g of 94 mm to cover the services GSM 900 and LTE low. These values are

Results of theoretical simulations and tests which have shown that the first monopole radiator height H _{u should be} between 15 and 25 mm, preferably between 15 and 19 mm and more preferably between 17 and 18 mm. The second

Monopole radiator height H _g should, according to the simulations and tests, be between 30 and 45 mm, preferably between 35 and 41 mm and in particular between 40 and 42 mm.

The length of the roof capacity D, due to the compact design of the

The length of the roof capacitance D _t , ie the first leg 14 of the second monopole radiator 13, preferably between 0 and 35 mm, preferably between 20 and 35 mm and in particular 35 mm.

The first monopole radiating width B _u and the second monopole radiating width B _g and the first monopole radiating depth T _u and the second monopole radiating depth T _g influence the bandwidth of the antennas formed by the monopole radiators 12, 13. The second monopole radiator 13 as a GSM radiator for a bandwidth of 180 MHz and the first monopole radiator 12 as a UMTS radiator for a bandwidth of 460 MHz are each a good

Ensure impedance matching. Therefore, the width and depth of the individual monopole radiators 12, 13 should not be chosen too small, so that the slenderness can remain low.

For optimization, the widths of the monopole radiators B _g , B _{u are selected} between 2 and 10 mm, preferably between 4 and 9 mm and in particular at 7 mm. The width of the roof capacity B _gt is preferably between 0 and 15 mm, more preferably between 5 and 10 mm and more preferably 8 mm. The second monopole radiator depth T _g is

preferably chosen between 0.5 and 7 mm, more preferably between 2 and 4 mm and more preferably at 3 mm. Since the roof capacity 14 is part of the second monopole radiator 13, it should also have the same depth. Since the first monopole radiator 12 must provide a larger working bandwidth than the second monopole radiator 13, it will is preferably made slightly wider, so that its depth is preferably in a range between 0.5 and 7 mm, more preferably between 4 and 6 mm and more preferably 5 mm.

Figure 2 shows an exploded view of the structure of the previously described

Multi-Range Antenna 1. It can be seen the contacting of the multigrade antenna 1 by means of a connection adapter 20 which is inserted into the cone radiator 3 and serves to receive the inner conductor 5 of the coaxial cable 6. The inner conductor 5 of the coaxial cable 6 is inserted through a corresponding opening of the ground surface 2 and a corresponding opening of the fixing ring 8 and thus enters the connection adapter 20 in order to connect the cone radiator 3 to the inner conductor 5.

FIG. 3 shows an alternative embodiment of a multirange antenna 1, which additionally has a GPS antenna 22. In order not to disturb the omnidirectional characteristic of the multirange antenna 1 described above, it can therefore be provided to provide a coaxial cable 6 with additionally a further inner conductor 21, which is provided by the

Cone radiator 3 is guided and the GPS antenna 22 between the monopole radiators 12, 13 contacted. This is possible because the conical surface 11 is normally de-energized. If this is made conductive, it can serve as a ground plane for the GPS antenna 22.

LIST OF REFERENCE NUMBERS

Multiband antenna

ground plane

cone spotlight

opening

inner conductor

coaxial

outer conductor

fixing ring

contact area

bearing surface

conical surface

first monopole emitter

second monopole emitter

first leg

second leg

connection adapter

another inner conductor

GPS antenna

Claims

claims

1. Multi-range antenna (1), in particular for use in a motor vehicle, comprising:

- A cone radiator (3) with an axis of symmetry (R) to put the cone radiator (3) with its expiring end perpendicular to a ground surface (2);

- A first monopole radiator (12) which connects in the direction of the axis of symmetry (R) to the cone radiator (3), wherein the first monopole radiator (12) with a side surface (9) of the cone radiator (3) is electrically connected.

2. Multi-region antenna (1) according to claim 1, wherein the first monopole radiator (12) is flush with the side surface (9) of the cone radiator (3).

3. Multi-range antenna (1) according to claim 1 or 2, wherein a second monopole radiator (13) is provided, extending in the direction of the axis of symmetry (R) to the

Connected cone radiator (3), wherein the second monopole radiator (13) with a side surface (9) of the cone radiator (3) is electrically connected.

4. Multi-region antenna (1) according to claim 3, wherein the second monopole radiator (13) is flush with the side surface (9) of the cone radiator (3).

5. Multi-region antenna (1) according to claim 3 or 4, wherein the second monopole radiator (13) with respect to the cone radiator (3) the first monopole radiator (12).

is arranged opposite.

6. Multi-range antenna (1) according to one of claims 3 to 5, wherein the second

Monopole radiator (13) has a roof capacity (14) which extends in particular transversely to its axis of symmetry (R) via the cone radiator (3).

7. Multi-range antenna (1) according to one of claims 1 to 6, wherein the

Multi-region antenna (1) at the outgoing end of the cone radiator (3) by an inner conductor (5) of a coaxial cable (6) is formed contactable.

8. multi-region antenna (1) according to one of claims 1 to 7, wherein a wider end of the cone radiator (3) has a conductive conical surface (1 1) on which a GPS antenna (22) is arranged, wherein the GPS antenna (22) via a of the cone radiator (3) insulated conductor (21) is contacted by the cone radiator (3).

9. multi-range antenna (1) according to one of claims 1 to 8, wherein a

Connection adapter (20) is provided to connect the inner conductor (5) of the coaxial cable (6) and the cone radiator (3) with each other.

10. Multi-band antenna arrangement with a multi-region antenna (1) according to one of claims 1 to 9 and a ground plane (2), in particular one

Exterior body surface of a motor vehicle.