EP2858176B1 - Multi-range antenna for a motor vehicle - Google Patents

Description

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 are in use in Europe, 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 should be capable of transmitting and receiving radio signals in different frequency bands.

In addition to the frequency bands implemented so far, for example for telecommunications services, radio signals for digital radio as well as future services such as LTE, WiMAX, WiBro, WLAN and UWB are to be operated. For example, these additional services may use another frequency range around 5.9 GHz for transmitting information between vehicles, i. H. for a car-to-car communication.

For all frequency ranges, it is desirable that the receive and transmit characteristics of a multirange antenna used be direction independent for all desired frequency ranges in the horizontal and that there be no shadowing by individual radiator elements in certain directions. For the multigrade antenna this means that the directional diagram over a high bandwidth has a good omnidirectional characteristic, ie no larger indentations, and the energy can be radiated uniformly in horizontal directions to the communication receivers.

The publication 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. The other of the legs is followed by an L-shaped monopole section.

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

Also from the publication US 7,286,095 is known a cone antenna, 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.

In the publication US 2003/0103008 A1 a multi-region antenna structure is shown in which a cone-shaped antenna portion 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.

The US 2005/134511 A1 describes a broadband antenna having a tapered portion and a monopole shape portion.

The US 6,693,600 B1 discloses a broadband antenna comprising a monocone and a monopole.

The US 2011/012802 A1 describes an antenna comprising a conically radiating element and a circular radiating element.

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 multirange antenna according to claim 1 as well as the multirange antenna arrangement according to the independent claim.

Further advantageous embodiments of the present invention are specified in the dependent claims.

• einen Konusstrahler mit einer Symmetrieachse, um den Konusstrahler mit seinem auslaufenden Ende senkrecht auf eine Massefläche aufzusetzen; und
• einen ersten Monopolstrahler, der sich in Richtung der Symmetrieachse an den Konusstrahler anschließt, wobei der erste Monopolstrahler mit einer Seitenfläche des Konusstrahlers elektrisch verbunden ist.

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 set up the cone radiator with its expiring end perpendicular to a ground surface; and
• a first monopole radiator which adjoins the cone radiator in the direction of the axis of symmetry, wherein the first monopole radiator is electrically connected to a side surface of the cone radiator.

An idea of the above multigrade antenna is to prevent, by a stacking arrangement of individual radiating elements, the cone radiator (cone-shaped radiator) and the first monopole radiator, shading in certain directions 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 make an impedance matching for the radiator elements for a frequency range of 2-3GHz only by sizing the cone radiator. In the lower frequency range up to 2-3 GHz, the impedance matching is achieved by the dimensioning of the monopole radiator.

Furthermore, the first monopole radiator can be flush with the side surface of the cone radiator. In particular, a second monopole radiator may be provided be, which connects in the direction of the axis of symmetry of the cone radiator, 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 can be arranged opposite the first monopole radiator with respect to the cone radiator.

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 has a conductive cone surface on which a GPS antenna is arranged, wherein the GPS antenna can be contacted by the cone radiator via a conductor isolated 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

Figur 1

eine schematische Seitenansicht einer Mehrbereichsantenne;

Figur 2

eine Explosionsdarstellung der Mehrbereichsantenne der Figur 1; und

Figur 3

eine alternative Ausführungsform einer Mehrbereichsantenne mit einer zusätzlichen GPS-Antenne.

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

FIG. 1

a schematic side view of a multi-region antenna;

FIG. 2

an exploded view of the multigrade antenna of FIG. 1 ; and

FIG. 3

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

Description of embodiments

FIG. 1 shows a schematic cross-sectional view of a multi-region antenna 1, which can be arranged on a ground plane 2. The ground plane 2 may be, 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 outgoing first end (end with a smaller cross-sectional diameter or the cover side of the cone radiator corresponding end), with which it rests on the ground surface 2, so that a second end, with respect to symmetry axis R of the cone radiator 3 opposite the expiring End having a larger diameter, spaced from the ground surface 2 is arranged.

The cone radiator 3 has a circular cross-section with respect to a plane parallel to the ground plane 2 and thus has an optimum omnidirectional characteristic. Alternatively, deviating from the circular cross section cross sections, 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. An 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, a fastening ring 8 is provided, which surrounds the cone radiator 3 and is supported on the ground surface 2. As a result, the cone radiator 3 reliably in aligned position on the ground surface. 2 and, in particular, bending of the cone radiator 3, so that its axis of symmetry R passes from the vertical 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 glued to the contact surface 8 at the contact surfaces between the outer surface of the cone radiator 3 and corresponding surfaces of the mounting ring 8 and on the support surface 10 of the mounting ring 8 on the ground surface 2 or secured in any other way.

The cone radiator 3 thus has a circumferentially extending, electrically conductive side surface 9 and a conical surface 11, which may be open or closed, electrically conductive or non-conductive.

In the illustrated embodiment, the conical surface 11 is made 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 conical 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 surface 2 direction). The second monopole radiator 13 is disposed substantially at an opposite portion of the edge of the cone surface 11 and is also perpendicular to the ground surface 2, d. H. in the same direction as the first monopole emitter 12, from.

The first monopole radiator 12 is formed as a rectilinear conductor, while the second monopole radiator 13 has a rectilinear conductor provided with a transverse roof capacitance 14. To form the roof capacitance 14, the second monopole radiator 13 is L-shaped with two legs 14, 15. 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 as the angle subtended by the side face 9 of the cone radiator 3, cone radiator height H _c as the length of the 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 _t as the length of the first leg 14 of the second monopole radiator 13, first monopole radiator width B _u as the width of the first monopole radiator 12 in the radial direction to the axis of symmetry R of Cone radiator 3, first monopole radiator depth T _u as the width of the first monopole radiator 12 in the tangential direction to the symmetry axis R of the cone radiator 3, second monopole radiator width B _g as the width of the first monopole radiator 12 in the radial direction to the symmetry axis 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 capacitance B _gt than the width of the first monopole radiator 12 in the direction of the axis of symmetry R of the cone radiator 3rd

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 a mounting ring 8 made of Plexiglas with a dielectric constant ε _r = 3.4, a preferred opening angle α = 48.65 ° given assumed infinite extent 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. In this way, standing waves on the conical surface are generated, which lead to the antenna terminal to an input impedance Z _in that 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 from 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 should Cone radiator height H _c 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 a frequency range of 780 MHz to 5.925 GHz and usually comprises 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. LTE low GSM 900 UMTS WiBro Low / high WiFi / WLAN WiMAX Low LTE high WiMAX high WiFi / WLAN C2C / DSRC f _min (MHz) 780 810 1710 2305/2345 2400 2495 2500 3300 5150/5470 5850 f _max (MHz) 860 960 2170 2320/2360 2485 2690 2690 3800 5350/5825 5925

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 in the cone radiator height usually also leads to 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 covered with further antenna structures, ie the monopole radiators 12, 13. By choosing the two narrowband monopole radiators 12, 13, the missing frequency ranges of the services that are in the frequency ranges not covered by the cone radiator 3, namely LTE low,

GSM 900 and UMTS, are operated. So that the monopole radiators 12, 13 do not disturb the omnidirectional characteristic of the cone radiator 3, they are arranged above the cone radiator 3.

To further reduce the overall height of the multigrade 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 jointly act as narrowband monopole radiators. Thus, the entire height of the multi-region antenna 1 can be 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 the 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. According to the simulations and tests, the second monopole radiator height H _g should 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 capacitance D _t should not be longer than the cone diameter, ie the diameter of the conical surface 11 due to the compact design of the multigrade antenna 1. Preferably, the length of the roof capacitance D _t , ie the first leg 14 of the second monopole radiator 13, is 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 to ensure a good impedance matching. Therefore, the width and depth of each should be Monopole emitters 12, 13 are not 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 capacitor _gt B 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 selected between 0.5 and 7 mm, more preferably between 2 and 4 mm and more preferably 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 is preferably made slightly wider, so that its depth preferably in a range between 0.5 and 7 mm, more preferably between 4 and 6 mm and more preferably at 5 mm.

FIG. 2 shows an exploded view of the structure of the multi-region antenna described above 1. One recognizes 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 multi-region 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 is therefore possible to provide a coaxial cable 6 with additionally an additional inner conductor 21 which is guided through the cone radiator 3 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

1

Multiband antenna

2

ground plane

3

cone spotlight

4

opening

5

inner conductor

6

coaxial

7

outer conductor

8th

fixing ring

9

contact area

10

bearing surface

11

conical surface

12

first monopole emitter

13

second monopole emitter

14

first leg

15

second leg

20

connection adapter

21

another inner conductor

22

GPS antenna

Claims (9)

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

   - a cone emitter (3) having an axis of symmetry (R), in order to fit the cone emitter (3) with its tapering end perpendicularly onto an earthing surface (2);

   - a first monopole emitter (12) which adjoins the cone emitter (3) in the direction of the axis of symmetry (R), wherein the first monopole emitter (12) is electrically connected to a side face (9) of the cone emitter (3),

   characterized in that
   a relatively wide end of the cone emitter (3) has a conducting conical surface (11) on which a GPS antenna (22) is arranged, wherein the GPS antenna (22) can be contacted by the cone emitter (3) via a conductor (21) which is insulated from the cone emitter (3).
2. Multi-band aerial (1) according to Claim 1, wherein the first monopole emitter (12) adjoins the side face (9) of the cone emitter (3) in a flush fashion.
3. Multi-band aerial (1) according to Claim 1 or 2, wherein a second monopole emitter (13) is provided which adjoins the cone emitter (3) in the direction of the axis of symmetry (R), wherein the second monopole emitter (13) is electrically connected to the side face (9) of the cone emitter (3).
4. Multi-band aerial (1) according to Claim 3, wherein the second monopole emitter (13) adjoins the side face (9) of the cone emitter (3) in a flush fashion.
5. Multi-band aerial (1) according to Claim 3 or 4, wherein the second monopole emitter (13) is arranged opposite the first monopole emitter (12) with respect to the cone emitter (3).
6. Multi-band aerial (1) according to one of the Claims 3 to 5, wherein the second monopole emitter (13) has a roof capacitor (14) which extends over the cone emitter (3), in particular transversely with respect to the axis of symmetry (R) of said monopole emitter (13).
7. Multi-band aerial (1) according to one of Claims 1 to 6, wherein the multi-band aerial (1) is embodied in a contactable fashion at the tapering end of the cone emitter (3) by means of an internal conductor (5) of a coaxial cable (6).
8. Multi-band aerial (1) according to one of Claims 1 to 7, wherein a connecting adapter (20) is provided for connecting the internal conductor (5) of the coaxial cable (6) and the cone emitter (3) to one another.
9. Multi-band aerial arrangement having a multi-band aerial (1) according to one of Claims 1 to 8, and an earthing surface (2), in particular an external surface of bodywork of a motor vehicle.

Images