EP1586135A1

EP1586135A1 - Antenna core

Info

Publication number: EP1586135A1
Application number: EP03702515A
Authority: EP
Inventors: Herbert Hein; Wulf Guenther; Harald Hundt; Achim Kipper; Matthias Reidel
Original assignee: Vacuumschmelze GmbH and Co KG
Current assignee: Vacuumschmelze GmbH and Co KG
Priority date: 2003-01-23
Filing date: 2003-01-23
Publication date: 2005-10-19
Also published as: JP4238221B2; JP2006513646A; US7508350B2; US20060022886A1; WO2004066438A1

Abstract

The aim of the invention is to create a highly bendable antenna core (8) which is highly bendable for high-frequency identification systems and which substantially retains its soft-magnetic properties when bending occurs. Said aim is achieved, according to the invention, by using specific amorphous or nanocrystalline alloys having a very low magnetostriction value. The antenna core (8) is embodied in the form of a laminate with/or without insulating layers placed therebetween. The invention also relates to an antenna provided with one such antenna core and to a method for the production thereof.

Description

description

antenna core

The invention relates to an antenna core of a length of at least ^'80 mm with at least one flexible soft-magnetic element of an amorphous or nanocrystalline alloy and a method for producing such aerial core method for producing an antenna and Verwen- fertil of such an antenna core.

EP 0554581 B1 discloses a laminated magnetic core for an antenna, which is used on an identity card or a credit card-like card and which consists of a stack of amorphous magnetic layers and film-like non-conductive layers, for example made of plastic, arranged in between. The antenna shown there requires flexibility insofar as an ID card is exposed to certain mechanical loads in daily use.

An antenna for a transponder with a magnetic core is known from EP 0762535. B1, which consists of different layers of a soft magnetic material, for example an amorphous magnetic material with or without interposed insulation layers in the form of paper or a polymer. Alternatively, potting tapes of the magnetic active material with plastics, for example resins, is also disclosed there. The version described there serves to create a flexible and unbreakable antenna. DE 19513607 C2 discloses a magnetic core member for a thin film antenna is known, wherein the magnetic core made of strips of an amorphous alloy or a nanocrystalline alloy, which may be isolated by insulating from each other, whereby a separation of the laminate layers is mentioned by their Ox ^'films possess.

A package of soft magnetic elements is also known, for example, from US Pat. No. 5,567,537, in which the use of certain amorphous and nanocrystalline alloys for the production of so-called thin-film antennas is described. Among other things, the criterion for the good usability of such thin-film antennas, for example in chip cards, is the retention of soft magnetic or other physical properties before and after a bending load. In particular, it is shown that, in contrast to ferrite bars, such thin-film antennas have no cracks after bending loads.

The US 5625366 discloses a flexible antenna core, which consists of different layers of an amorphous alloy as a laminate, wherein a strand-like bundle of strand-shaped magnetically active bodies is additionally mentioned, between which a film insulation can be provided if necessary. The possibility is also mentioned of producing insulation of the individual elements by means of an oxide layer or another layer which can be created, for example, by chemical treatment of the magnetic elements

For really strongly deformable antennas, in particular longer, voluminous antennas with a wire winding, the amorphous and natural known from the cited prior art are nocrystalline alloys and especially the inner structure of the antenna cores are only suitable to a very limited extent. To date, only non-deformable ferrite cores have been used in motor vehicle access systems.

So none of the known antennas offers perfect function even when bent.

It is therefore an object of the present invention to provide an antenna core which ensures a strong deformability of the antenna without the magnetic properties of the antenna being significantly changed by the deformation.

Furthermore, it is an object of the present invention to provide a manufacturing method for such an antenna core, which is inexpensive and can be used on an industrial scale, and an antenna with such an antenna core.

According to the invention, the object is achieved in that the amorphous or nanocrystalline alloy has a magnetostriction value λ _s in the range from 4 * 10 ^"6 to -4 * 10 ^{" δ} . The alloy preferably has a magnetostriction value λ _s in the range from 1 * 10 ^{~ 6} to -l * 10 ^"s on.

Such a low magnetostriction value makes the antenna core very insensitive to bending with regard to its magnetic properties.

Furthermore, the amorphous or nanocrystalline alloy can have a linear BH loop, the inductance L of the antenna core changing at 60 kHz during a central bending by 25% of its length by less than 10%. The quality can advantageously be chosen so that it is greater than 10 at 60 kHz. Quality is the ratio of inductance and resistance multiplied by the angular frequency.

For example, strand-like strands can be provided as elements. However, it can also be particularly advantageous for the elements to be designed as flat strips or strips which are rectangular in cross section.

It is advantageous that the elongated soft magnetic strips have a thickness of 5 to 30 micrometers. An antenna core can be made of the ^• ■ soft magnetic elements of considerable length (for example greater than 8, especially more than 30 cm) can be produced, which can be further processed as an independent self-supporting component to an antenna for at a suitable point in a larger device ( eg door handle) or in particular can be installed in a motor vehicle.

The invention can also advantageously be implemented in that the elements are separated from one another by electrically insulating films. The electrically insulating films can be made of plastic, for example. It can be advantageous that the foils have a thickness of 0.5 to 30 μm. The use of electrically insulating foils, which preferably consist of plastic and typically have a thickness of 0.5 to 30 μm, results in laminates which ensure very good deformability with very low eddy current losses.

Various tests have shown that the packages known from the prior art, which are made with adhesives such as For example, epoxy resin were glued, sometimes leading to unsafe insulation between the layers of the soft magnetic tapes and thus to fluctuating quality values. There was tension in the soft magnetic alloy strips, which in turn caused instability of the inductors.

In some cases, the natural insulation layer on the surface of the soft magnetic alloy strips is insufficient to ensure high quality values Q and reliable resistance to deformation.

Due to the manufacturing process, some soft magnetic alloy strips have a surface structure that changes over the length of the strip and has, for example, elevations and depressions. Such elevations then touch the neighboring band layers and, depending on many factors, enable electrical through-plating with frequently fluctuating transition resistance.

The use of plastic insulating films has proven to be advantageous in special cases, so that antenna cores can be produced which have high and very stable quality values Q. This full-surface insulation between all belt layers suppresses any eddy currents between the individual belt layers. Thus, only the thickness of the individual soft magnetic alloy strips and their electrical conductivity are decisive as a criterion for the quality. The alloy strips preferably have a thickness of 5 to 30 μm. In many cases, depending on the requirements of the electrical wiring, the insulating foils can be omitted if certain eddy currents can be accepted.

The antenna cores mentioned are preferably produced by a method according to the invention, which has the following steps:

One or more soft magnetic elements are wound into a toroid, the wound toroid is severed at one point, opened and shaped back into the elongated antenna core.

Before winding, the elements can also be alternately layered with insulating foils. The soft magnetic elements can advantageously be produced using rapid solidification technology.

In a further development of the present invention, n times the number of tape layers are wound for each antenna core when winding the toroid. After the toroid has been cut through, a number n of packets is produced, from which n antenna cores then emerge by separating the packet in the envelope.

The following additional step is provided in a development of the method according to the invention:

- On the soft magnetic element, the soft magnetic properties (for example permeability, shape of the BH- Loop, coercive field strength, magnetostriction etc.) set,

Alternatively, the elements can be cut individually and, preferably in a receiving body, layered to form the antenna core.

The antenna core consisting of one or more soft magnetic elements is preferably stabilized in order to protect the elements and to enable the winding.

On the one hand, the antenna core can be placed between two rectangular flat bars. The resulting “sandwich” can be further developed into a rod-shaped winding body by wrapping it with adhesive tapes. The reshaped antenna core can also be further developed with a curable resin to form a winding body.

It is also conceivable to insert the opened antenna core into a U-shaped profile and to bring it to its final shape by wrapping it with adhesive tapes.

The inductance of the rod antenna is then adjusted by adapting the magnetic iron cross section A _{Fe of} the antenna core to a winding former before stabilization by adding or removing individual band layers or sections of band layers to the inductance value that will later be necessary for the antenna ,

Alternatively, however, the inductance of the rod antenna can also be adjusted in that the winding of the antenna core by adding or removing individual turns to the value of the antenna which will later be necessary Inductance is adjusted. It can also be provided that by adding other soft magnetic elements, both the inductance is set and the course of the magnetic flux is designed.

In addition, the inductance of the antenna can be adjusted by adapting the winding of the foil package to the value of the inductance that will later be necessary for the antenna by moving the winding or individual turns in relation to the length of the antenna core.

The winding for the antenna to be manufactured can be made of stranded wire, wire, cable or the like.

Typically, the edges of the antenna core have regular depressions in which the winding wires for the antenna winding are held. In addition, the distance and the position of the winding on the antenna core is clearly defined.

In a special embodiment, the resulting antenna package is placed between two pre-hardened and pre-hardened fiber mats, which are also called prepregs. The resulting ensemble is then pressed in a heated mold into a body with free-form geometry. By curing the resin in this form, the body is finally fixed.

Further advantageous embodiments of the invention can be found in the subclaims.

The invention also relates to the use of an antenna according to the invention in a motor vehicle. Especially Installation between a moving part of the motor vehicle (for example door) and its chassis is advantageous.

The invention is described below with reference to exemplary embodiments shown in the figures of the drawing. It shows:

Figure 1 shows a basic structure of an antenna core according to the invention;

FIG. 2 shows a completely wound antenna consisting of an antenna core according to the invention and a winding;

FIG. 3 shows an alternative embodiment of a fully wound antenna,

FIG. 4 shows an antenna core wound into a toroid bifilar,

FIG. 5 shows an antenna core according to the invention produced by cutting open the toroid from FIG. 4 and then opening it,

FIG. 6 shows a structure of an antenna core made of soft-magnetic, strand-like elements without insulating foils,

FIG. 7 shows a two-part, angled antenna core,

FIG. 8 shows an antenna core made of soft magnetic tapes without insulating foils,

FIG. 9 steps in the manufacturing process of an antenna, Figure 10 and Figure 11 is a motor vehicle in outline, and

Figure 11 shows the installation of an antenna according to the invention in a motor vehicle.

As can be seen from FIG. 1, according to the present invention the antenna core consists of several alternately layered elongated soft magnetic bands or strips 1 made of an amorphous or nanocrystalline alloy. If necessary, there are insulating foils 2 between the strips 1, which electrically isolate the strips 1 from one another. In conjunction with appropriate evaluation electronics, the foils can also be omitted, for example when used in a motor vehicle access system. In addition, the antenna core is stabilized and fixed with some adhesive tapes 3.

It can be seen from FIG. 2 that an antenna according to the invention has an elongated antenna core 8 which is provided with a winding 4. The ends 5, 6 of the winding 4 enable the supply and discharge of electrical current. The elongated antenna core is provided with stiffening strips 7, which are made of plastic, placed on the bottom and top for stabilization.

By using soft magnetic strips made of an amorphous or nanocrystalline alloy with the lowest possible magnetostriction, which is between +4 • 10 ^"6 and -4-10 ^{" 6} , preferably + l-10 ^"s to -l'10 ^{" δ} , the considerable bending of the antenna core by two 90 degrees shown in FIG. 2 is possible without a significant change in the soft magnetic and physical properties. A further alternative embodiment of an antenna core according to the invention can be seen from FIG. Here it is possible to adapt the outer shape to any necessary installation conditions by means of a multiple torsion of the package forming the antenna core without sacrificing the electrical and magnetic properties. In the exemplary embodiment shown, the two power connections 9, 10 of the winding were led out on only one side.

As can be seen in FIG. 4, a strip or tape is cast from an amorphous alloy by means of rapid starter technology, which is then adjusted with regard to its soft magnetic properties by means of heat treatment in a magnetic field. This is preferably done in the form of a coil.

Depending on whether it is intended to use an amorphous alloy or a nanocrystalline alloy, the setting of the nanocrystalline structure takes place in the course of this heat treatment.

The amorphous alloys are usually cobalt-based alloys and the nanocrystalline alloys are usually iron-based alloys. Both alloy systems have long been known in the technical field and are described, for example, in US Pat. No. 5,567,537 cited at the beginning.

The alloy strips are then bifilarly wound into a toroid 11, for example together with an electrically insulating film, which preferably consists of plastic and typically has a thickness of 0.5 to 30 μm. Each individual band layer of the amorphous or natural nocrystalline alloy strips are electrically isolated from the adjacent strip layers by the foil. The completely wound toroid 11 is shown in FIG. 4.

Then this completely wound toroid is cut through at one point, opened and shaped back into the elongated antenna core 8, which is typically trapezoidal at both ends after being opened, as can be seen from FIG. 5.

In order to demonstrate the influence of the structure according to the invention on the properties of the antenna, comparative measurements were carried out on pattern antennas with the following alloys:

Table 1

As an example of an antenna, a bifilar stack of amorphous alloy ribbons made from alloy No. 1, which is currently sold by the applicant under the Vitrovac® 6025 brand, was produced. The alloy strips used had a thickness of 23 + 3 μm. A plastic film made of Hostaphan® with a thickness of 6μm was used as the film.

The soft magnetic amorphous alloy ribbon has received a field heat treatment at a temperature of 200 ° C for about 18 hours across the ribbon direction prior to being processed into a package. The resulting bra Loop is a largely linear F-loop. This results in a largely linear BH loop with a relatively small remanence ratio of <0.3.

The dimensions of the antenna core produced according to the invention were:

Length 750 mm, width 20 mm, 48 layers of amorphous alloy tape. The invention is particularly suitable for antennas with a length of 80 mm, in particular 300 mm, in particular for antennas of motor vehicle access systems.

The antenna core was provided with a winding with 110 turns of enamelled copper wire with a diameter of 0.5 mm. The wound length of the antenna was approximately 700 mm centered.

As an alternative to this antenna, an antenna B with identical dimensions and from an identical starting material, but without film insulation, was produced.

As a further alternative, an antenna C with identical dimensions and made of a magnetic tape with a thickness of 17 + 3 μm but without foil insulation was also produced. The soft magnetic material became a antenna before being processed

Field heat treatment along the belt direction, which led to a so-called Z-loop, i.e. a strong non-linear, rectangular B-H loop with a high remanence ratio of> 0.7.

In addition, an antenna was produced from a slightly aggressive alloy 2 from Table 1 with foil insulation (D) and without foil insulation (E). The Soft magnetic amorphous alloy tape was also subjected to a field heat treatment transverse to the tape direction before being processed into a package, the heat treatment being carried out for 6 seconds at a temperature of 310 ° C. and the magnetic field being applied transverse to the tape direction. This again resulted in a largely linear flat bra loop.

Furthermore, an antenna (F) was produced from a more magnetostrictive alloy (alloy No. 3 from Table 1) with a foil insulation. The soft magnetic amorphous alloy strip used was also subjected to a field heat treatment transversely to the strip direction before being processed into a package, the heat treatment being carried out for 6 seconds at a temperature of 350 ° C. transversely to the strip direction. A largely linear B-H loop was again achieved.

The following properties listed in Table 2 were then measured in the straight state and in the deformed state. The deformation was caused by a central bending of the respective antenna cores by 20 cm.

Table 2

While examples A and D have a high inductance L which is largely independent of the deformation and at the same time high quality Q, comparative examples B, C, E and F have an inductance L which is sometimes more sensitive to voltage.

In the case of examples B, C and E, they also have a poorer quality Q.

In particular, in examples B and E, compared to embodiments A and D, there are certain changes in the inductance as soon as the antenna stack has been deformed and then straightened again. However, these changes are justifiable for typical transponder applications with suitable control.

In addition, it is striking that in the case of comparative example C there is a particularly small value of the inductance results. In comparative example C, the bra bow is rectangular. The small value of the inductance is all the more surprising since the rectangular BH loop is much steeper than the linear loop of the other examples, so that there is a significantly higher average permeability. A significantly better inductance should therefore occur.

Comparative example F also showed unstable measured values and a very high sensitivity to mechanical loads.

In a further experiment, an antenna pattern with a torsional load of 180 ° or a bend to a closed ring (circular shape) was measured. For this purpose, an antenna (G) was produced from a bifilar-made package of amorphous alloy ribbons from alloy No. 1 of Table 1 with a thickness of 23 + 3 μm and a film made of the plastic Hostaphan® with a thickness of 6 μm. The soft-magnetic amorphous alloy strip had been subjected to a field heat treatment transverse to the strip direction before being processed into a package, so that a largely linear flat F-loop was present.

The dimensions of the antenna produced were: length 750 mm,

Width 20 mm, 60 layers of tape with a winding with 88 turns of enamelled copper wire with a diameter of 0.5 mm. The length wound in this case was approximately 700 mm centered.

The antenna cores again showed excellent properties (Table 3) with regard to inductance L and quality Q. Table 3

Overall, the present invention accordingly makes it possible to produce antenna cores which can be subjected to excellent mechanical stress, and which are also simple and can be produced on an industrial scale.

FIG. 6 shows an antenna core 12, which is formed from strand-like soft magnetic elements 13 consisting of an amorphous or nanocrystalline alloy without the interposition of insulating layers. This antenna core 12 has the advantage over an antenna core layered from strip-shaped strips that it is mechanically easier to bend in all directions.

FIG. 7 shows an antenna core 14 which is constructed in two parts, one part remaining without a winding and the second part being provided with a winding 15. This is an example of the fact that in addition to a laminate-like part, the antenna core can contain further parts for aligning or bundling the magnetic flux. FIG. 8 shows an antenna core 16 which is fixed in a curved shape and which consists exclusively of a stratification of strip-shaped strips 1 with a rectangular cross section without the interposition of insulating layers. The ^strips' 1 can on the one hand onsschichten by their natural oxidation, on the other hand also by other surface layers which may for example be generated by a chemical pretreatment can be electrically separated from each other. In some cases, through-contacting may occur due to surface roughness of the tapes, but the eddy current losses for typical applications in the transponder range, for example, remain in the range around 125 kHz and the electronics used there are acceptable.

FIG. 9 shows a method for producing an antenna core, in which the strips 1 are first inserted one after the other into a mold 17 which is designed as an open frame. This frame can in turn have a thin frame. A winding 18 can be applied thereon, which can be wound up, for example, in notches which are arranged on the outer edges of the frame 17. In the next step, the intermediate product formed in this way can be glued, cast or wrapped with bandages and then a shrink tube 19 can be pulled over and shrunk on. In the bottom part of FIG. 9 the shrink tube is shown in the shrunk-on form. There, the ends 20, 21 of the antenna core are pressed flat and wide by means of an embossing with a pressing tool, as a result of which the shrink tube can also be tightly connected at the ends to the inner part of the antenna core. However, the ends of the shrink tube can also be coated on the inside with an adhesive, for example a hot glue, which allows a tight connection with the parts of the antenna core to be enclosed.

The connections 22, 23 of the antenna core are fastened on the frame 17 and serve for fastening and contacting the two ends of the winding 18. There, a line can be connected which emerges from the shrink tube at the end 21.

Provision can also be made for additional soft magnetic parts to be inserted into the frame 17, which serve to guide the magnetic flux. For this purpose it can also be provided that certain soft magnetic parts are already integrated in the frame 17 as a kind of pole shoes before the strips 1 are inserted, or that the frame 17 already consists entirely of a soft magnetic material.

The frame 17 can also exist in a three-dimensionally curved shape before the strips 1 are inserted, or can be bent together with the strips after the strips have been inserted to form the intended three-dimensional form.

FIG. 10 shows a motor vehicle 24 in which an antenna 25 for a transponder is integrated in the area of the right passenger door. As shown, the antenna extends from the door handle 26 to a flashing light 27, in the vicinity of which the body of the motor vehicle is broken, so that one end of the antenna is also made of metal

Outer skin of the motor vehicle can leak. In the same way, a corresponding antenna can be attached in the area of the tailgate 28 or the bonnet 29 or a rear door. organize. In the area of the tailgate, the antenna can then emerge from the tailgate handle on the one hand and from the rear window, in the area of the bonnet it can exit from the front bonnet edge on the one hand and in the area of the windscreen on the other. In this way, a large antenna length is achieved in each case, the antenna ends projecting out of the metallic outer skin of the vehicle, however, the bendability of the antenna which is possible according to the invention while maintaining full functionality is also a prerequisite when the door is opened.

FIG. 11 shows a view of the motor vehicle of FIG. 10 from above, the antenna 25 being shown in a stretched form with the passenger door closed.

FIG. 12 shows an enlarged view of the area in which the antenna 27 is located. 28 there denotes an area in which the antenna is not provided with a winding, which essentially serves to guide the magnetic flux.

A plurality of antennas according to the invention can also be provided on a motor vehicle of the type shown in order to realize a larger transmission / reception range or to be sensitive to different orientations of the magnetic field.

An application is conceivable both for actuating devices of the locking system of a motor vehicle and for recognition and identification applications.

The antenna cores according to the present invention can be used in motor vehicles, for example also use in detection systems for anti-theft systems as the transmitting and / or receiving antennas. Such anti-theft systems are described for example in EP 0 121 649 B2 or US 4, 150, 981. However, applications are also conceivable, in particular as stationary antennas for personal registration and / or in billing systems (for example stationary antennas for the identification and billing of ski passes).

Claims

claims

1. Antenna core of at least 80 mm in length with at least one flexible soft magnetic element (1, 13) made of an amorphous or nanocrystalline alloy, in which the amorphous or nanocrystalline alloy has a magnetostriction value λ _s in the range from 4 * 10 ^"6 to -4 * Has 10 ^"6 .

2. Antenna core according to claim 1, wherein the alloy has a magnetostriction value λ _s in the range from 1 * 10 ^{~ 6} to -1 * 10 ^"6 .

3. Antenna core according to claim 1 or 2, in which the amorphous or nanocrystalline alloy has a linear B-H loop and that the inductance L of the antenna core changes at 60 kHz during a central bending by 25% of its length by less than 10%.

4. antenna core according to claim 1, 2 or 3, wherein the quality at 60 kHz is greater than 10.

5. Antenna core according to one of the preceding claims, in which the elements are strand-like strands (13).

6. Antenna core according to one of claims 1-4, wherein the elements are flat, cross-sectionally rectangular strips or strips (1).

7. antenna core according to claim 6, wherein the elongated soft magnetic strips (1) have a thickness of 5-30 microns.

8. Antenna core according to claim 1 or one of the following, in which the elements (1) are separated from one another by electrically insulating foils (2).

9. antenna core according to claim 8, wherein the electrically insulating films (2) consist of plastic.

10. antenna core according to claim 8 or 9, wherein the films (2) have a thickness of 0.5 to 30 microns.

11. A method for producing an antenna core (8) according to one of the 'preceding claims with the following steps: one or more soft magnetic elements (1) are wound into a toroid (11), the wound toroid (11) is severed at one point, opened and formed back into an elongated antenna core (8).

12. The method according to claim 11, wherein the elements (1, 13) are manufactured in rapid solidification technology.

13. The method according to claim 11 or 12, wherein the elements (1, 13) are adjusted by means of heat treatment in a magnetic field with regard to their soft magnetic properties.

14. A method of manufacturing an antenna with an antenna core according to any one of claims 11 to 13, with the following

Step: the elongated antenna core (8) is mechanically stabilized to a winding body and provided with a winding (4).

15. The method according to any one of claims 11 to 14, in which the antenna core (8) is placed between two rectangular flat bars and the flat bars and the antenna core by U-wise with adhesive tapes or potting or impregnation with a hardenable plastic and subsequent curing to one rod-shaped bobbins are formed.

16. The method according to claim 15, in which further ferromagnetic elements are added to influence the orientation of the magnetic flux before wrapping with adhesive tapes or casting or impregnation.

17. The method as claimed in one of claims 11 to 16, in which the antenna core is formed into a rod-shaped winding body by inserting between two pre-hardened and pre-hardened fiber mats and then heating the mold.

18. The method according to any one of claims 11 to 15, in which recesses are made in the edges of the antenna core, which receive the winding wires for the antenna winding.

19. The method according to claim 18, in which the depressions are introduced regularly, so that the distance and the position of the turns of the antenna winding are exactly defined.

20. A method for producing an antenna with an antenna core according to one of claims 1 to 10, in which the soft magnetic elements are placed in a frame made of a stable material and then provided with a winding. hen and that the antenna body thus created is covered at least in the region of the winding with a shrink tube.

21. The method according to claim 20, wherein the shrink tube is coated at least in the region of its ends with an adhesive, in particular a hot melt adhesive, by means of which it is glued to the antenna core or in itself.

22. A method for producing an antenna with an antenna core according to one of claims 1 to 10, in which the soft magnetic elements are inserted into a frame made of a stable material and provided with a winding thereon and that the antenna body thus created is at least in the region of the Winding is covered with a bandage and glued and that the ends of the antenna body are each provided with a shrink tube for sealing, which is coated in particular on the inside with an adhesive.

23. Use of an antenna according to one of claims 1-10 in a motor vehicle.

24. Use of the antenna according to claim 23, in which the antenna has two regions, one of which the region of the antenna is fastened to the chassis and the other region to an element which is movable relative to the chassis.

25. Use of an antenna according to one of claims 1-10 in person detection and / or in accounting systems.