DE202022000086U1 - Multifunctional RFID radar tag system - Google Patents

Abstract

Multifunctional RFID radar label system, with a large number of resonators applied to a carrier material, characterized in that a combination of both slot line resonators (10) and stripline resonators, which on the one hand are used as a multi-frequency half-wave dipole (5) and on the other hand, are designed as a multi-frequency quarter-wave resonator (7), with the slotted line resonators having different resonant frequencies which can be determined wirelessly by a remotely positioned reading device and whose frequency pattern contains digital information, with the stripline resonators, which are designed as a half-wave dipole (5), at the low specified operating frequency, it represents a dipole which is open on both sides and has an electrically effective length of half a wavelength at the low specified operating frequency nted and at the high specified operating frequency represents a dipole which is open on both sides and has an electrically effective length of more than twenty times half the wavelength at the upper specified operating frequency and where the strip line resonators, which are designed as a quarter-wave dipole (7), at the low specified operating frequency, a two-sided open circuit represents a dipole with an electrically effective length of a quarter wavelength at the low specified operating frequency and at the high specified operating frequency represents a double-ended dipole with an electrically effective length of more than ten times the quarter wavelength at the upper specified operating frequency.

Description

The invention relates to a system of modular, functionally expandable RFID radar labels for interaction with high-frequency electromagnetic fields for different distances. Depending on the intended task, the function of these labels can be modularly expanded by replacing or modifying existing components or by adding additional structures and other electronic components during the production of these labels or at a later point in time. In addition, combinations or compilations of a number of different mutually compatible embodiments are possible at low cost, depending on the task to be performed. Depending on the requirements and as far as this is technically possible, the labels are preferably produced by printing in order to minimize the production costs. Additional components in hybrid technology are only required in higher expansion stages of the modularly expandable system, which cannot yet be printed with the current state of the art. The labels are either stuck directly onto the objects to be marked or attached in some other way, or they form the central building block for functionally extended system components and are then appropriately integrated into them.

Technical Fields

Depending on the expansion stage, several technical areas are involved. In the simplest modular expansion stage, the labels serve to improve road safety.

An elementary function of these labels is that they act as purely passive radar retroreflectors and thus a radar system, such as those used in the automotive industry to increase driving safety, even in the edge area of the radiation characteristics of the respective radar system, sufficiently significant backscattering of the Provide radar system generated radar beam to indicate the presence. This function is also fulfilled for larger distances of up to 100 m.

In a higher modular expansion stage, identification is also possible in addition to the indication of presence. Through additional, purely structural measures, information can be stored in the label without additional electronic components, which can be read by specially suitable readers even over distances of a few meters.

The data stored in this way is comparable in terms of data volume to the optoelectronically readable bar code or barcode that has been known since 1952. In contrast to the bar code, however, no line of sight is necessary. Therefore, these labels can still be read even if they have been attached to objects that are covered by other objects. For example, packaged objects can also be identified through the packaging, or a special package can be determined in a large number of packages stacked one behind the other, or a bicycle can be provided with a remotely readable individual identifier, for example.

In the most complex modular expansion stage, an additional chip module is simply pressed into a special label, which means that this label can then process very large amounts of data, which can be entered or written with suitable reading and writing devices over short distances, typically in the range of up to one meter. can be read out. In terms of data volume, this function is comparable to the widely used Near Field Communication or NFC tags. In contrast to these, however, the multifunctional RFID radar labels presented here still work reliably when they are attached directly to a metallic, conductive object.

State of the art

Radar retroreflectors for generating strong backscatter for radar systems have been known since 1943 and were used for the first time as so-called chaff for radar deception.

Modern radar retroreflectors are used in various embodiments, particularly in nautical applications, for smaller boats or buoys in order to significantly improve their visibility on radar devices, despite their small dimensions.

The exposition DE 1129192 A [01] with the designation "radar reflector" and the priority of June 3, 1958 describes the radar retroreflector shape already known at the time, consisting of a unit of eight triple mirrors. The specification claims a "radar reflector consisting of a unit of eight corner cubes with coincident apexes, formed of flexible material and enclosed and held taut by an inflatable envelope of wave-permeable material". This is characterized in that "the reflector is a precise fit within the envelope such that its outer edges abut and are secured to the inner surface of the envelope."

The physical principle of this form of radar retroreflector has served as the basis for numerous applications to date.

In the pamphlet WO2017055516A1 [02] entitled "Retroreflective Sign, Retroreflective Sheeting, and Method of Manufacture", this well-known principle is now applied to light beams to enhance retroreflectivity of signs, according to the present invention. Applicant claims therein a "retroreflective sign comprising a corner cube structure, the corner cubes having at least three mirror surfaces arranged at right angles to one another for retroreflection". This sign is characterized in that "the corner cube is formed as a depression in a surface of the sign and forms mirror surfaces which are formed reflective from the air side."

There are numerous methods for storing additional, remotely readable data in radar tags. Through a special structuring during the manufacturing process or afterwards, resonances can be generated in conductive materials that are suitable for the exchange of data with the help of special reading and writing devices. No additional electronic components are required for the labels for this form of data labels. The term "chipless RFID tag" has become established to describe these labels. An up-to-date overview of the various ways of storing and reading data through structuring is given in the article entitled "A Review on Chipless RFID Tag Design" [03].

The possibility of placing the electrically conductive structuring on the corresponding objects by printing, similar to the case with the bar code, is particularly cost-effective. The publication entitled “Design of Chipless RFID Tags Printed on Paper by Flexography” [04] provides detailed study results.

The current state of the art in the field of chipless RFID with a futuristic outlook on possible future developments is described very comprehensively by Smail Tedjini [05] in the article entitled "Chipless RFID, State of the art and Current Developments".

Contactless data exchange has also been established in the form of near-field communication with the abbreviation NFC since 2002. Since then, sufficiently large amounts of data can be easily exchanged and due to the mass production of the electronic components required for this, the NFC chips, labels of this type are now extremely inexpensive.

As an example of the relevant prior art, the publication WO2017140628A1 [06] entitled "Lighting Unit with Near Field Communication, Integrated Circuit and Methods Therefore". Block diagrams, signal curves and flow charts in connection with NFC are discussed there.

A typical modern application that expands the possibilities of the NFC method with modified antennas is in the publication EP3210587A1 [07] labeled “Medical Container with NFC Antenna”. There, the originally planar NFC antennas are modified in such a way that the required chip on the label can communicate with the reader at any time, regardless of the position of a cylindrical container.

Presentation of the shortcomings of the previously known versions

Depending on the frequency range in which the radar system is operated, retroradar reflectors according to [01] are relatively bulky in order to generate the strongest possible backscattering of the radar beam, which can hit the retroradar reflector from any direction.

In contrast, triple reflectors embossed in metal for predominantly horizontal and largely frontal irradiation according to [02] are planar and therefore significantly flatter in design. However, they are currently only available for the optical range.

Both designs are neither designed nor suitable for storing additional data.

Radio tags, which can be used as data storage without additional electronic components according to [03], or in the cost-effective production according to [04], are in the number of their data volume, because of the relatively large areal structures compared to modern semiconductor technology according to the required resonators [05], severely restricted. In addition, a subsequent change of the data is only possible with great technical effort. Such a radio tag has a range of only a few meters and is not suitable for determining presence over a greater distance. NFC labels according to [06] can electronically store and read very large amounts of data due to special integrated electronic chips. However, only very short distances of a few centimeters can be bridged and the reading and writing device must be positioned planar to the NFC label. Should, however, three-dimensional Objects are detected, so voluminous modifications of the antennas of the NFC tag according to [07] are required, which means that the modified NFC tag is only suitable for special applications. A significant interaction with a radar system over longer distances is not possible. In addition, NFC tags have the problem that they are operated by an external feed field, which is inductively coupled to the tag. This supply field breaks down completely in the vicinity of a metallic conductor, which means that communication with the reading and writing device is then not possible.

The technical problem

It is the object of the invention to provide a system of modular, functionally expandable labels for the interaction with high-frequency electromagnetic fields, which are operated without their own energy source. Both the properties of a radar retroreflector, which can still be recognized from a large distance by a radar system, and the properties of radio tags, whose limited data can be read for medium distances in the range of a few meters, as well as extensive data volumes comparable to NFC tags can still be safely written or read at a distance of less than one meter.

means of solving the problem

By exchanging or modifying existing components or by adding additional structures and additional components to these labels, the function of these labels can be expanded in a modular manner during manufacture or at a later point in time. In addition, all of the embodiments are compatible with each other, allowing a combination or assembly of a number of different embodiments depending on the task to be accomplished at low cost.

Depending on the requirements and as far as this is technically possible, the labels are preferably produced by printing in order to minimize the production costs. Additional components in hybrid technology are only required in higher expansion stages of the modularly expandable system, which cannot yet be printed with the current state of the art. The labels are either glued or attached in some other way directly to the objects to be marked, which can be made of any material, or they form the central building block for functionally expanded system components and are then appropriately integrated into them.

Further details can be found in the patent claims or are explained in connection with the description of the exemplary embodiments.

exemplary embodiments

The primary intention of the invention explained here is the reliable detection of objects from a great distance, that is to say typically from distances of up to 100 meters.

The secondary intention of the invention explained here is the limited informative recognition of the object, with an information volume, similarly limited to the currently used linear barcode systems, from medium distances, up to about 5 meters.

The tertiary intention of the invention explained here is the fully informative recognition of the object from short distances, i. H. typically below one meter, with a data volume limited only by cost and expediency, as is the case with regard to the amount of data that can be stored in a similar manner in the systems for NFC near-field communication already in use today.

First, the physical basis for the retroreflector functionality of the radar labels will be explained and some exemplary implementations and numerical examples or geometric dimensions for a frequency of 77.5 GHz of the electromagnetic radiation emitted by the radar system will be given. It is then easily possible for a person skilled in the art to adapt the conditions explained for radar systems with other operating frequencies by simple scaling.

It is known that the radar cross-section or the effective reflection area σ of an object depends in particular on the frequency range, the material of the object and especially the shape, which results in different angles of incidence and reflection of the radar radiation.

First, the planar shape of a retroreflector is considered. To explain the physical conditions, this should initially be aligned perpendicularly to the radar system, i.e. reflect the incoming wave of the radar system exactly back to the source like a mirror.

The serves to illuminate the physical relationships 1 . A metallically conductive, planar structure as a topside metallization (1), shown here as a rectangular metallization with a width W and a length L as an example, is located on top of a non-conductive dielectric substrate (2) with the height H and faces the radar installation. On the underside of the substrate (2) there is also a metallically conductive planar structure as underside metallization (3). This does not have to be structured, but its area should be larger than the top side metallization (1) or it can cover the entire underside of the substrate.

At first glance, such a structure is very similar to a so-called microstrip patch antenna. However, there are significant differences. For example, no transceivers with an impedance of 50 ohms are connected here. Nothing is connected in this particular case. The structure appears self-sufficient and, despite the amazing similarity, is not a component of any microstrip circuit. Rather, only the electrical properties of chaff located in free space, such as those used for radar deception, are simulated by this arrangement. For this purpose, some technical parameters must be observed as precisely as possible, as explained below. Modern chaff, for example, are made of hair-thin conductive synthetic fibers that are released in large numbers to fully reflect radar pulses.

The metallization on the underside (3) and the substrate (2) are used here to simulate the free space electrically. The underside metallization (3) forms the necessary high-frequency reference potential and defines it. This makes the electrical conditions independent of the material to which it is attached on the back. For example, the side of the sub-metallization (3) facing away from the radar system can be glued both to a conductive metal surface and to non-conductive cardboard without the electric field in the substrate (2) being affected by the nature of the material on which the label is attached , would be affected.

In anticipation of the possibilities explained below of reading almost unlimited amounts of data through the labels presented here in the near field, it should be noted that almost all currently available NFC labels can no longer be read as soon as they are stuck on a metallic conductive surface, because the im Eddy currents generated by metal dampen the feed field of typical reading devices too much and thus collapse.

The geometric spacing between the upper side metallization (1) and the lower side metallization (3) is determined by the height H of the substrate (2). In order to simulate the electrical conditions as in a free space with regard to the field structure that becomes effective for the upper side metallization (1) and generated by the radar system, it is only necessary to adjust the geometric distance to the electrically effective distance in such a way that the geometric height H is as exact as possible corresponds to a quarter wavelength λ of the wave excited by the radar system in the substrate.

Odd multiples of the quarter wavelength λ are also possible from an electrical point of view, but this would significantly increase the volume, which would limit the number of possible applications in practice.

The electrical wavelength λ is changed by the medium. If, for example, a microwaveable hydrocarbon-ceramic laminate with a dielectric constant ε _r of 3.624 is used as the substrate (2), the following relationship applies to the height H of the substrate (2) for an assumed operating frequency of the radar system of 77.5 GHz:

The wavelength in vacuum λ ₀ is calculated as: $${\lambda }_0=\frac{299792.458}{77500}\text{mm}\text{.}$$

The free space wavelength is thus 3868 micrometers at this operating frequency. Due to the medium with the dielectric constant ε _r , the wavelength is then shortened to the value that becomes effective in the substrate (2): $$\lambda =\frac{{\lambda }_0}{\sqrt{e_{\mathrm{right}}}}.$$

The wavelength in the substrate (2) is therefore 2032 micrometers. A quarter of the wavelength in the substrate must then be used for the height H, so it must apply: $$\text{H}=508\mathrm{\mu }\text{m}\text{.}$$

This is the minimum necessary height H for the substrate (2). This is a practical value for realizing the labels as self-adhesive individual labels, tapes or large-area foils.

For custom-made products and more special purposes, such as an even greater range, an odd multiple of the quarter-wavelength can also be used, i.e. the height H = 1524 µm for three times a quarter-wavelength or even H = 2540 µm for five times a quarter-wavelength, etc .

However, the greater the substrate thickness and thus the height H, the less flexible the label. With increasing geometric height H of the substrate, the achievable range for the interaction of the label with the radar system increases because the stray field between the upper side metallization (1) and the lower side metallization (3) increases structurally and the interaction with the far field becomes more intensive as a result. which corresponds to an increase in the effectively effective reflecting surface σ, but the flexible foil then becomes a rigid plate with limited possibilities for mounting on the object to be marked.

Computer calculations are necessary to optimize the interaction between the radar system and the label in order to shape the upper side metallization (1) if surfaces with complex borders are used. For those at the in 1 However, with the simple rectangular structure used as an example, the situation can be explained clearly.

At least one of the specified geometrical dimensions, i.e. the length L or the width W, must be selected in such a way that the upper side metallization gets into resonant oscillations due to the transmission energy radiated by the radar system at the operating frequency of the radar system. Thus, for example, we choose the length L just long enough that it corresponds to a dipole open on both ends at half the wavelength of the transmission frequency of the radar system. For this purpose, the geometric length L must correspond to the electrically effective length of a dipole with either half the wavelength of the high-frequency pulses emitted by the radar system or a multiple thereof. On the other hand, stray fields form at the ends of the resonance line, which is open-ended on both sides, and act like capacitances. These so-called end-effect capacities depend on the frequency, the material and the geometric dimensions [08]. Because of these end-effect capacitances, the geometric length L must be chosen to be an equivalent amount shorter, which corresponds to these capacitances, i.e. the geometric length L and the additional electrical lengths corresponding to the length of the stray field occurring at both ends must be 2 times ΔL then correspond to half the electrically effective wavelength, or a multiple thereof.

However, since the top-side metallization is linked on the one hand to the field in the substrate and on the other hand to the field in free space, a so-called hybrid mode is formed, since the phase velocities in the two media are different. As a result, the effectively effective permittivity is dependent in particular on the width W of the rectangular upper-side metallization, which is why no generally applicable value for the electrically effective wavelength can be specified at this point. Depending on the configuration of the geometries used, this must be determined with the aid of suitable computer programs.

For an assumed rectangular conductor strip as the upper side metallization with a negligible layer thickness and with an arbitrarily specified width W = 1.0 mm, the following values would then result for the structure treated here as an example:

The effectively effective permittivity ε _eff is higher than that of air and lower than that of the substrate and can be calculated for a strip conductor with a width W of 1mm to a value: $$e_{eff}=\mathrm{2,804.}$$

nach der Berechnung somit λ_eff = 2310 µm. Eine halbe Wellenlänge wäre dann also eine Länge von 1155 µm. Der Endeffekt [08] für eine solche Struktur bewirkt aufgrund des Streufeldes an dem leerlaufendem Ende der Leitung eine äquivalente zusätzliche Leitungslänge $$\Delta L=23\mathrm{\mu }\text{m}.$$

This results in an effective wavelength for such a strip-shaped upper side metallization with the associated electromagnetic field: $${\lambda }_{eff}=\frac{{\lambda }_0}{\sqrt{e_{eff}}},$$

after the calculation therefore λ _eff = 2310 µm. Half a wavelength would then be a length of 1155 µm. The net effect [08] for such a structure causes an equivalent additional line length due to the fringing field at the open end of the line $$\Delta L=23\mathrm{\mu }\text{m}.$$

$$\text{L}=1155\mathrm{\mu }\text{m}-46\mathrm{\mu }\text{m},$$

$$\text{L}=1109\mathrm{\mu }\text{m}.$$

This equivalent replacement length acts on both sides, so the following applies to the geometric length of the rectangular top-side metallization operated as a half-wave dipole: $$\text{L}=0.5\cdot {\lambda }_{eff}-2\cdot \Delta L,$$

$$\text{L}=1155\mathrm{\mu }\text{m}-46\mathrm{\mu }\text{m},$$

$$\text{L}=1109\mathrm{\mu }\text{m}.$$

In order to enlarge the reflecting surface σ, it is expedient to extend the length L to a multiple of half the wavelength, provided that the geometric surface required for this is available. To do this, the determined geometric length simply has to be multiplied by a natural number. A length L = 22.18 mm would therefore correspond to twenty times the effective wavelength chen and at the same time be in resonance with a significantly increased reflecting surface σ.

In principle, the width W of the upper side metallization can be chosen arbitrarily in the case of this upper side metallization selected by way of example for the purpose of explanation. However, the aspects explained below must be taken into account. If this width W is chosen to be very small, i.e. less than 1 mm, the characteristic impedance of the conductor strip increases and as the width W decreases, the field structure associated with this conductor strip and thus the characteristic impedance of the arrangement approaches the free space impedance of 377 ohms, what would then mean optimal power matching to free space, which would strengthen the interaction with the field generated by the radar installation. This is the reason for the effectiveness of the hair-thin chaff used for radar decoy. On the other hand, if the strip is too narrow, the electrically effective electrically conductive surface of the upper side metallization (1) is reduced, as a result of which the reflecting surface σ is reduced. In the case of chaff, this disadvantage is compensated for by a large number of individual dipoles exported into space. With a limited number of labels or with a single label, however, a compromise must be found between the adaptation to the free space impedance and the overall metal surface available to produce the largest possible reflective surface σ.

The following figures show qualitatively some suitable structures for the surface metallization (1) as examples of suitable planar resonance elements of labels.

It shows the 2 strip-shaped conductor strips according to in 1 shown and explained rectangular surface metallization (1). The lengths of the conductor strips correspond to a multiple of half the wavelength and are therefore in resonance with the local electromagnetic field generated by the radar installation. In order to achieve the best possible matching of the resonance elements to the free space, the conductor strips are made relatively narrow, which means that their characteristic impedance approaches the free space impedance of 377 ohms. On the other hand, in order to achieve a sufficiently large reflecting surface σ, several conductor strips are arranged parallel to one another, as a result of which the interactions of the individual conductor strips add up.

The downside of the in 2 The arrangement shown is that the interaction with the radar system depends very much on how the polarization directions of the radar antennas are designed. This could result in significantly different reflecting surfaces σ, depending on whether the label is rotated by 90 degrees or not, for example. This disadvantage is provided by a structure 3 raised up. The metallizations shown there act like dipoles, which are polarized either horizontally, vertically or rotated by 45 degrees. This means that the interaction with the radar system is largely independent of the polarization of the transmitter's antenna system. In the case of galvanically connected different resonators, the connection points must have the same potential. In the 3 the crossover area of the two diagonally arranged resonators is in a so-called common voltage node, ie at this point the magnitude of the voltage in both resonators disappears and there is no mutual influence due to the galvanic connection at this point. This also applies to the structures shown below.

A particularly simple structure for dipole resonators for horizontally and vertically polarized antennas is shown in 4 . For a strong interaction with the radar system, it makes sense to attach a large number of such structures to the label in order to achieve a sufficiently large reflecting surface σ.

The structure in FIG 5 . There, linearly polarized transmitting antennas of the radar system rotated by 45 degrees are also optimally detected.

A further enlargement of the reflecting surface σ results from the fan-shaped widening or widening of the conductor path width W towards the open end of the dipole resonators. the 6 shows this extension. From an electrical point of view, this structure corresponds functionally to that in 4 shown resonator structure. In contrast to this, however, the width W of the rectangular surface metallization (1) is not constant, but rather increases more and more towards the open end of the dipole resonators. This increases the area of the metallization required for interaction with the radar system. However, it should be noted that due to the larger width W at the open end of the resonance line, the magnitude of the end effect capacitance increases due to the larger stray field. As a result, with the same resonance frequency, resonators of this design are shorter than the rectangular resonance elements considered above, corresponding to the equivalent equivalent length ΔL caused by the changed end effect in each case.

the 7 From an electrical point of view, largely corresponds to that in 5 shown structure, but now the respective dipole resonators fan-shaped are moderately designed. Here, too, the lengths of the dipole resonators must be reduced by the increased equivalent replacement length ΔL so that the structures resonate at the operating frequency of the radar transmission system.

A horizontally and at the same time vertically polarized dipole resonator with the maximum possible reflection area σ is in 8th shown. Electrically, this structure is similar to that in 4 shown surface metallization, but here the width W has been chosen to be just equal to the length L. Here, too, the respective geometric dimensions must be shortened in accordance with the equivalent equivalent lengths resulting from the stray field at the open end of the resonators.

By widening the fan-shaped structures according to the 7 finally results in the in 9 structure shown. This is now completely independent of the polarization of the transmitting antennas of the radar systems and enables a completely direction-independent interaction with the maximum possible reflection area σ.

For the sake of completeness, further planar resonant structures are listed below as examples, which either have the same resonance frequency with different geometric dimensions or also have different resonance frequencies and can therefore interact with radar systems that operate simultaneously on different frequencies such as 77.25 GHz and 24.125 GHz radiate electromagnetic energy or these structures are suitable for several radar systems that have been designed for different operating frequencies such as 77.25 GHz or 24.125 GHz. Then the same labels can also be used universally for different systems.

the 10 Fig. 12 shows schematically a number of free-running resonant lines at the end of different lengths, which either correspond to different multiples of half a wavelength at an operating frequency or, alternatively, are also suitable for different wavelengths and different operating frequencies. As soon as the metallization of the respective strip-shaped resonators touches, ie as soon as they are galvanically coupled to one another, the contact points must be structurally arranged at the point where the voltage distribution generated by resonance has a zero point. In the case of a strip-shaped dipole resonator, this would always be exactly in the middle of the respective conductor. Accordingly, this is taken into account in the structures shown as examples. Strip-shaped resonators of different lengths are shown schematically, which are galvanically coupled, but can nevertheless interact with the respective existing electromagnetic field largely independently of one another, even at different resonance frequencies.

More functionally very similar to the in 10 shown, each acting as a resonator top metallization (1) are in 11 shown as an example. The multiple resonance frequencies are caused here by lengths of the conductors that have different electrical effects, which are caused by lateral slots being produced in the fan-shaped structure, which increase the inductance per unit length and thus lengthen the electrically effective length of the fan-shaped structures or through the conductor structure generated holes, which cause a reduction in the capacitance per unit length and thus a shortening of the electrically effective length of the fan-shaped structures. both in 11 The surface metallizations shown can each interact with the electromagnetic field at three different resonance frequencies at the same time and can therefore be used universally for different radar systems.

All of the retroreflectors considered so far are planar structures and only work optimally if the upper side metallization (1) - similar to light and an optical mirror - is aligned almost perpendicularly to the direction of incidence of the radar beam. In practice and with moving objects, however, this is by no means always the case.

For a typical application, in which several containers marked by labels or other objects are to be found in a larger storage area between unmarked third-party containers, technical solutions using multifunctional RFID radar labels are given below. It can be assumed that the radar beam will mainly hit the horizontal plane, because a portable radar system for detecting marked objects will not be in the air or on the ground, with the azimuthal angle of the incoming radiation having all values from 0 to can cover 360 degrees. If the position in relation to the radar system is undetermined, i.e. the radar beam to be reflected can hit it from an undetermined direction, then there are various options for causing a significant reflection of the radar beam.

A practical possibility is the complete, polygon-like enclosing of the object to be marked with retroreflectors. If the retroreflectors are planar structures, then only a sufficiently large number of these reflectors are attached to the object to be marked in such a way that at least one of these reflectors is aligned largely perpendicularly to the incident radar beam.

For example, it would be conceivable to mark a column that, depending on the diameter of this column, 200 such planar retroreflectors are glued or printed to a film or tape, lined up laterally to form a polygon and attached along the circumference of the column. This procedure would open up a technical possibility of using planar, i.e. two-dimensional labels, to mark an object to be found again completely in the plane, regardless of the direction from which the radar beam strikes the object marked by the labels during the search. Such a structure, composed of planar retroreflectors and shaped like a polygon, could also be produced as a continuous self-adhesive tape and cut to the appropriate length as required.

There may also be perforations in the tape after each planar label to allow the required length to be obtained by simply tearing it off at the appropriate point without the use of tools, as is the case with a roll of postage stamps.

As an alternative, very effective non-planar, i.e. three-dimensional retroreflectors can be realized with a higher level of technological effort in production, which can be easily integrated as suitable hybrid elements into the system of modularly expandable, multifunctional RFID radar labels if the task justifies the higher production costs. This is a three-dimensional surface structure known as Perkin-Elmer pyramids. the 12 shows a schematic of such a three-dimensional Perkin-Elmer pyramid surface structure. It is a large number of evenly arranged cube-shaped structures, with the cubes, viewed from the front, showing one corner towards the viewer. The three side surfaces of three adjacent cubes result in funnel-shaped depressions, which, with total reflection on the respective surfaces, throw an incident light beam back exactly in the direction from which it came. The surface formed in this way forms a structure with numerous triple mirrors continuously lined up next to one another. It is used in practice for high-quality optical reflectors. These reflectors use a suitable, optionally colored plastic with a sufficiently high refractive index as the material. The resulting total reflection means that the surfaces do not need to be mirrored, which further reduces the manufacturing costs. The edge lengths of the individual cube structures determine the structure sizes. These are typically in the range of 2 mm for inexpensive reflectors and up to 4 mm for high-quality reflectors.

In principle, however, it is technically also possible to design these optical reflectors in such a way that they reflect both the light and the electromagnetic radar beams according to the same physical principle. For this purpose, with an operating frequency of the radar system of, for example, 77.5 GHz, the respective edge lengths of the dielectric triangular corner reflectors currently used would have to be lengthened to about three times and the surfaces would have to be metallized.

With the same number of reflectors, the total size would then triple. However, as a compromise between size and effectiveness, the number of individual triangular reflector elements can be reduced in order to create overall more practical proportions.

While low-loss, transparent materials with a sufficiently high refractive index are available inexpensively for electromagnetic radiation with a very high frequency, namely light, this is not the case for electromagnetic radiation with a significantly lower frequency, namely the radiation from the radar system. These suitable materials are currently significantly more expensive. Thus, the effect of total reflection cannot currently be used to construct reflectors structured in this way for inexpensive production due to a lack of suitable materials, so that metalized surfaces then have to be used for radar systems. Basically, this three-dimensional surface structure, as shown in 12 is shown, but suitable for all electromagnetic radiation if the surfaces are designed in such a way that total reflection of the incident radiation is effected for the respective frequency range. Depending on the intended application, professional adjustments or scaling must then be made for the relevant frequency range. According to the estimates given above, structure sizes in the range of 10 mm to 12 mm and a metallically conductive mirrored surface of the triangular corner reflectors would be expedient for the realization of retroreflectors constructed in this way for radar systems with an operating frequency of 77.5 GHz.

On the one hand, the technical complexity and thus the costs for producing such retroreflectors that are suitable for frequency ranges of radar systems are significantly higher than for conventional optical retroreflectors. On the other hand, the use of metal and structure sizes up to the centimeter range results in a very effective retro-reflector, which very effectively reflects both radar beams and light beams back to the source at the same time. This gives the multifunctional RFID radar labels additional application options in the field of traffic safety if these hybrid elements are combined with each other in a modular way.

In addition to the previously considered simple reflection of electromagnetic energy with planar or three-dimensional retroreflectors, which is detected by the radar system as proof of the presence of an object, the radar labels are designed in such a way that information in the form of digitally formed data can also be transmitted.

one inside 13 The planar multifunctional label structure (4) shown as an example, which is suitable for the applications listed above and can be expanded for additional functions, is described below.

The two fan-shaped resonance lines of the planar multifunctional label structure (4) have - from a physical point of view - largely the 1 structure shown. So they consist of a top metallization (1), a dielectric substrate (2) as a carrier material and a bottom metallization (3).

the 13 shows the structure of the top metallization (1). In addition to a multi-frequency half-wave dipole (5) and a multi-frequency quarter-wave resonator (7), this also has an additional slot line metallization (9). Within this slot line metallization (9) there are numerous slot line resonators (10), each with different geometric lengths. These are each short-circuited at the ends and thus form slot line resonators (10) whose resonant frequency depends significantly on the electrically effective overall length of the slot line resonator (10). The details of programming and recognition of the programmed data in connection with slotline resonators can be found in [03].

the 13 shows in the example shown only eight slot line resonators (10), each with different geometric lengths, for technical reasons. However, the number of slot line resonators (10) can be increased to a larger number as required. The only limitation is the available area of the slot line metallization (9), with a sufficiently large distance between the individual resonators being observed so that they do not falsify the respective resonance frequencies due to excessive coupling.

In addition, there is a mounting pit (6) between the two multi-frequency, fan-shaped resonance lines for accommodating a hybrid chip module (14). The basic functioning of this planar multifunctional label structure (4) is explained below.

The larger of the two large, fan-shaped metallizations on the upper side is designed as a multi-frequency half-wave dipole (5). This dipole is open-ended at both ends. Therefore, voltage maxima are to be expected at both ends in the case of resonance when excited by an external electromagnetic field, such as that generated by a remotely stationed radar system.

In this exemplary embodiment, the multi-frequency half-wave dipole (5) is structured as a circular segment with a constant radius and thus a constant electrically effective resonator length. The geometric width is at its maximum at the empty end facing away from the assembly pit (6). Therefore, there is also a maximum stray field here, which can interact intensively with the free space. So that this interaction is hindered as little as possible, a sufficiently large dielectric free space (8) with a maximum distance from other metallizations that may have a damping effect, which corresponds to a quarter of the wavelength at the lowest resonant frequency and a minimum distance of one sixteenth of the wavelength at the corresponds to the lowest resonance frequency. The lowest resonant frequency is about 2.42 GHz in the arrangement dimensioned here as an example without taking into account the different frequency-dependent values for the end effect, and the intended resonant frequency for the interaction with the radar system is significantly higher at 77.5 GHz. Thus, even the smallest distance is still a multiple of the wavelength of the operating frequency of the radar system and thus only plays a subordinate role with regard to possible damping of the fields.

The smaller of the two large, fan-shaped metallizations on the upper side is designed as a multi-frequency quarter-wave resonator (7). This is empty only on the side facing away from the assembly pit (6). By in the assembly pit (6) located diameter metallization (11), the multi-frequency quarter-wave resonator (7) is galvanically connected to the underside metallization (3) and thereby at the same time to the high-frequency ground potential. the 14 shows the geometric and electrically effective details as a lateral sectional view.

The large, uninterrupted, continuous underside metallization (3) forms the high-frequency grounding potential of the arrangement. The substrate (2) with the height H separates the entire top metallization (1) at a distance from the bottom metallization (3) that corresponds to a quarter wavelength with respect to the operating frequency of the radar system in order to simulate free space conditions and to have the most intensive interaction with the radar system to allow.

The multi-frequency half-wave dipole (5), which is open-ended on both sides, has a length that corresponds to the distance between the two marking points B and C in 14 is equivalent to. Point B is located directly at the assembly pit (6). Point C is at the opposite, fan-shaped end of the resonant line.

The multi-frequency quarter-wave resonator (7) has a length that corresponds to the distance between the two marking points A and G in 14 is equivalent to. Point G is located directly at the assembly pit (6). Point G is galvanically connected to the underside metallization because of the metallization (11). Point C is at the opposite, fan-shaped end of the resonant line.

the 15 shows the electrical conditions and voltage curves on both resonance lines at the operating frequency of 77.5 GHz of the radar system.

The voltage is at its maximum at point A, that is, at the end of the multi-frequency quarter-wave resonator (7) that is idling. After a distance that corresponds to 16 times half the wavelength and also a simple quarter wavelength, the voltage at point G, which as a grounding point is galvanically connected to the underside metallization (3) through the through-metallization (11), disappears. There is therefore an intensive interaction with the search beam emitted by the radar system, with the effective area available for interaction corresponding to more than 16 times the area of a simple half-wave dipole simply because of the geometric distance between points A and G.

The voltage is at its maximum at point B, i.e. the open end of the multi-frequency half-wave dipole (5). After a distance that corresponds to 32 times half the wavelength, the voltage at the end, which is also free-running, also reaches a maximum at point C. There is therefore an intensive interaction with the search beam emitted by the radar system, with the effective area available for interaction corresponding to more than 32 times the area of a simple half-wave dipole simply because of the geometric distance between points A and G.

The lateral dimensions of the assembly pit are chosen so that the distance between points G and B corresponds to three quarters of a wavelength. In this case, the entire upper side metallization (1) consisting of the multi-frequency half-wave dipole (5) and the multi-frequency quarter-wave resonator (7) and the stray field in the assembly pit can be like a large resonator tuned to the frequency of the radar system with a total length that is 50 times as long of a half-wave dipole at this frequency, interact intensively. The frequency of the radar system of 77.5 GHz is approved for the localization of distant objects for the automotive industry. Due to the resonators tuned to this frequency with an optimally large effective area of the planar multifunctional label structure, a significantly improved backscatter level can be expected than would be the case without this label.

The 16 the course of the voltages on the resonance lines.

The wavelength at the operating frequency of 2.42 GHz is 32 times longer than at 77.5 GHz. This results in the following electrical voltage profiles on the resonant lines for the given geometric dimensions for this frequency range.

The voltage is at its maximum at point A, that is, at the end of the multi-frequency quarter-wave resonator (7) that is idling. After a distance corresponding to a quarter of a wavelength, the voltage disappears at point G, which as a grounding point is galvanically connected to the underside metallization (3) through the through-metalization (11).

In contrast, the voltage is maximum at point B, i.e. the open end of the multi-frequency half-wave dipole (5). After a distance that corresponds to half a wavelength, the voltage at the end, which is also free-running, also reaches a maximum at point C. A maximum possible voltage difference is established between points G and B when the two resonance lines are exposed to the interrogation field of a reader with a feeding transmitter with a frequency of 2.42 GHz. If you were to connect an electrical load between points G and B, you could feed this electrical load with the energy required for operation by exciting the two resonant lines with an external field.

The figures described below serve to explain the details of the integration of such an electrical consumer using the example of a hybrid chip module (14).

the 17 shows the top view of the planar multifunctional label structure (4) as a detailed view in the area of the assembly pit (6). The tapered ends positioned on the substrate (2) of the multi-frequency half-wave dipole (5) and of the multi-frequency quarter-wave resonator (7) can be seen. The lateral contour of the mounting pit (6) shown here as an example is not completely circular, but is flattened on one side in order to enable easy positioning of a chip module that is optionally to be mounted. Since the substrate (2) is typically a film, this contour can be easily realized with the help of a punch.

If the planar multifunctional label structure (4) is only intended to serve as a retroreflector for a radar system, then neither the mounting pit (6) nor the chip module (14) are required. However, if larger amounts of data are to be stored in the planar multifunctional label structure (4), then a suitable ASIC (18), such as is also used for NFC labels, must be integrated into the multifunctional label structure (4). Depending on how the ASIC is structured and which functions are desired, a diode may also have to be integrated. In 18 shows how all the necessary operating conditions can be achieved by an additionally produced gap (12) in the metallization of the multi-frequency half-wave dipole (5) and an additionally attached diode (13). According to current research results, the diode (13) can also be applied to the substrate (2) in printed form.

At this point, it is expressly pointed out that all the two-dimensional, ie purely planar, embodiments described so far can be produced entirely by printing. In this case, instead of ink, a suitable metallically conductive layer is printed directly onto a dielectric material with the structures required in each case.

In the simplest case, one could print the labels on a cyclically perforated self-adhesive plastic film with a defined height and defined permittivity and then separate these labels from the other labels at the perforation like a self-adhesive stamp and stick them directly to the metal housing to be marked. The slotted line resonators for each label can be produced individually with different lengths and thus different resonant frequencies during the printing process.

Just as every printed bank note has a basically the same appearance but a different numbering, the basic structure of the top side metallization is also, for example, according to (1). 13 initially printed in the same way for all labels and in a further printing process, for example, metallically conductive short circuits are then printed at different points in the slots of the respective slot line resonators (10). Due to the short circuits at different points, the electrically effective lengths of these slot line resonators and thus the different resonant frequencies are already determined during printing. In terms of printing technology, it is therefore possible to individually set the physically effective lengths of the slotted line resonators (10) and thus the resonant frequencies generated by the resonators for each individual label print. The individual data of the respective labels encoded by the slot line resonators (10) with different lengths by the printing process can then be read out with suitable reading devices in a manner similar to a bar code or bar code. Further details on the physical background of reading this programmed data are exemplified in [03].

Up to the previously described expansion stage of the system presented here with modular, functionally expandable RFID radar labels for interaction with high-frequency electromagnetic fields for larger, medium and short distances, all exemplary discussed exemplary embodiments can be produced extremely inexpensively using only printing technology and do not require any further electronic components. To put it bluntly for level 1 RFID radar tags, i.e. for greater distances, and for level 2 RFID radar tags, i.e. for medium distances: These tags do not require any additional electronic components, i. H. they don't have a chip!

An electronic chip in the form of an ASIC (18) is only required for expansion stage 3, i.e. for short distances and for writing and reading larger amounts of data, but it only works with a DC voltage as the supply voltage.

A diode is therefore required in order to generate a DC voltage from the high-frequency supply field, which then supplies the electronic components in the ASIC (18). It is either an additional diode, for example mounted by printing, as explained above by way of example, or the diode is integrated directly in the ASIC (18).

Known developments can be used to save costs. The chips integrated in NFC labels, for example, are very well suited and can also be used here directly as ASIC (18). However, the diodes integrated in these NFC chips are suitable for a frequency range of 13.56 MHz, for example, but not for a frequency range of 2450 MHz, as would be required for the labels presented here. Therefore according to 18 a diode that can also be produced by printing is provided if the diode already integrated in the ASIC (18) is not suitable for the frequency range of the label. According to current research results, the limit frequencies of the diodes produced by printing technology are well above 40 GHz. This means that both configurations, namely those according to 17 and the according 18 are possible and only depend on the properties of the ASIC (18) used.

• Solange die beiden Resonatoren, nämlich der multifrequente Halbwellendipol (5) und der multifrequenten Viertelwellenresonators (7) über große Entfernung als Radarretroreflektor wirken, bleiben die in der 15 dargestellten Spannungsamplituden unterhalb der Schwellenspannung und es findet kein Stromfluss durch die Diode statt. In diesem Fall wirkt die Diode wie ein Widerstand mit nahezu unendlich großem Wert. Dadurch wird keiner der beiden Resonatoren (5) und (7) bedämpft und sie verhalten sich in elektrischer Hinsicht daher so, als würden sie sich, ähnlich wie die Düppel, isoliert im freien Raum befinden. Die Diode wirkt also wie ein Schalter, der den ASIC (18), der ja Betriebsenergie benötigt wenn er aktiviert ist, vom Resonator galvanisch trennt, wodurch dieser durch keine Last bedämpft wird.

In both cases, the fact that the diode does not allow any current flow until the threshold voltage is exceeded, i.e. it behaves similarly to an open switch, results in the following very important fact, which makes the multiple use of surface metallization possible in the first place:

• As long as the two resonators, namely the multi-frequency half-wave dipole (5) and the multi-frequency quarter-wave resonator (7) act as a radar retroreflector over long distances, they remain in the 15 voltage amplitudes shown below the threshold voltage and there is no current flow through the diode. In this case, the diode acts like a resistor with an almost infinitely large value. As a result, neither of the two resonators (5) and (7) is damped and, from an electrical point of view, they behave as if they were isolated in free space, similar to the chaff. The diode acts like a switch that galvanically separates the ASIC (18), which requires operating energy when it is activated, from the resonator, so that it is not damped by any load.

It is only when the reader, which operates at a significantly lower frequency than the radar device, is activated at a short distance that the significantly higher field strengths of the reader positioned nearby result in the in 16 shown voltage curves with sufficiently large voltage amplitudes and only then does the diode allow a current to flow, which dampens the resonant circuit. In this case, however, this is desirable, because the reader continuously supplies the energy drawn from the resonance lines, since the reader can build up a sufficiently strong electromagnetic feed field due to the short distance to the multifunctional RFID radar tag.

In 19 shown. This chip module is designed in such a way that it can also be retrofitted into the RFID radar label at any time 13 can be retrofitted if the functionality of the RFID radar label is to be increased.

The chip module (14) can be divided functionally into three levels in this exemplary embodiment shown schematically. The bottom of the chip module is formed by the chip module base (15). This is used to attach the required components. In the 19 it can be seen that the ASIC (18) is mounted directly on it, for example with the aid of an adhesive. The necessary electronic components are thus located above the chip module base (15) in the assembly area (16). The necessary connecting wires such as the grounding line (19) and the supply line (20) are also connected to the ASIC here. The supply line fixation is located above it. In this area, the lines rising from the assembly area are cast in a stable manner and routed to the outside. Since both the grounding line (19) and the supply line (20) are bent when the chip module (14) is inserted into the mounting pit (6), they must be fixed sufficiently well beforehand because of the forces that occur in the process.

the 20 shows a side view of the chip module (14) as a schematic sectional drawing and explains further details. The exemplary embodiment shown there shows the chip module (14) as an electronic component cast in a hollow body. The chip module base (15) is realized here using a solid material, which mechanically stabilizes the hollow body so that it does not deform when it is pressed into the assembly pit (6). If, for example, a copper or aluminum disk is used for the solid material, this has the advantage that the ASIC (18) attached to it can, if necessary, be grounded and cooled at the same time.

A casting compound in the supply line fixation (17) also serves to mechanically stabilize the hollow body and fix it the grounding line (19) and the supply line (20). It can also be seen that both the chip module base (15) and the mounting area (16) are tapered in diameter towards the bottom. As a result, the chip module (14) can be integrated very easily into the planar multifunctional label structure, because the housing of the chip module (14) is both self-guiding and self-adjusting as a result of these measures, which significantly reduces the tolerance requirements during assembly and thus the assembly speed increased and assembly costs reduced.

The following figures show the basic steps for assembling the chip module (14). However, these are not drawn to scale in order to clarify the various phenomena occurring during assembly. In particular, the cross-section of the chip module (14) is too small, the layer thicknesses of the metallization for the multi-frequency half-wave dipole (5) and for the multi-frequency quarter-wave resonator (7) are too large, and the wire thicknesses of both the grounding line (19) and the supply line (20) also shown too large compared to the geometric dimensions of the assembly pit. However, this significantly clarifies the essential processes of simultaneous contacting and fixing and makes understanding easier for the person skilled in the art.

However, despite the representation not being to scale, it should be noted that this is a press fit, which means that the cross-sectional dimensions of the assembly pit (6) - in contrast to the representations in Figures (21) to (23) - are slightly smaller than are the cross-sectional dimensions of the chip module (14). The substrate (2) is therefore elastically deformed during the pressing-in process and thus causes pressing forces after assembly, which fix the chip module (14) in its position. In addition, the metallization for the multi-frequency half-wave dipole (5) and the multi-frequency quarter-wave resonator (7) are notched and deformed when pressed in by the wires of both the grounding line (19) and the supply line (20), which results in a low-resistance and time-stable electrical contact connection without further ado Measures such as soldering results. the 21 schematically shows the situation immediately before assembly. The chip module (14) is located near above the assembly pit (6) and is lowered towards it. In the exemplary embodiment shown here, there is an adhesive (21) that was additionally deposited at the bottom of the assembly pit (6).

During the pressing-in process, the chip module base (15) immediately finds the upper opening of the assembly pit (6), because the chip module base has a significantly smaller extent laterally due to the narrowing. This is similar to the problem of putting a rod through a ring. The larger the ring diameter and the smaller the rod diameter, the easier and quicker it is to solve the problem. When more advanced press-in process is now, because of in the 17 and 18 non-circular shape of the cross section of the assembly pit (6) shown, additionally a rotation about the center axis of the chip module (14) caused by positive locking takes place until the in 19 shown straight side of the chip module (14) with the in 17 and 18 match the straight sides of the assembly pit (6) that can be seen. Only then do the forces causing a rotation, which are additionally generated by the pressing-in process and cause a rotation, disappear.

The chip module, which has been adjusted in all directions, is then pressed in further and the two lines, namely the grounding line (19) and the supply line (20) are first kinked at the edges of the upper side metallization (1). the 22 shows the kinking of the ground line (19) of the chip module (14) at the edge of the multi-frequency quarter-wave resonator (7) and the kinking of the supply line (20) of the chip module (14) at the edge of the multi-frequency half-wave dipole (5).

In 23 shows the state after the chip module (14) has been pressed into the mounting pit (6). The chip module (14) is now completely in the assembly pit (6). The respective lines of the chip module are galvanically connected to the resonant lines on the surface of the substrate by pressing, in a similarly durable manner to plastic deformation when crimping with crimping pliers. The adhesive (21) is not required for the assembly and serves as a security measure primarily to ensure that the chip module cannot be exchanged without authorization in order to possibly subsequently falsify the data stored in the ASIC (18) of the chip module (14).

Some useful application-specific configurations of the multifunctional radar labels are presented below as examples.

For applications in which retroreflectors are to be effective in the horizontal plane, but further information only has to be read out at close range, the combination of a sufficient number of planar labels, which can be produced extremely inexpensively, e.g. B. according to 7 with a single label, which is somewhat more complex to produce 13 , in which case no chip module (14) has to be inserted into the latter if the amount of information given by the programmed slot line resonators (10) is sufficient. Otherwise, by inserting a chip module (14), the amount of data stored can be significantly increased as required.

Such an exemplary realization is in 24 shown. A sufficiently large number of inexpensive planar retroreflector labels form a band-like structure. These labels are attached to a film, for example, and lined up side by side. They form a band that could be tied around a column, for example, with the effect that at least one of the retroreflector labels always reflects fully in the desired horizontal direction like a mirror, even though each individual label was only produced in a very inexpensive planar form is. The number of inexpensive labels according to 8th is here in the 24 only reduced for reasons of clarity and must be adapted in practice depending on the given requirements. According to the planar multifunctional label structure, which is more complex to produce 13 is the central part of the ensemble as a single label.

In this way, identification features can also be assigned for bicycles, for example. In this way, ownership can be saved or a clear assignment of names can be made between the respective bicycle and its owner. This would make it possible to provide every bicycle with an electronic license plate that can be read wirelessly. This would enable the respective bicycle to be clearly identified, as is already the case, for example, by the number plate on a motor vehicle. In the event of a bicycle being stolen, this would not only make it very easy to identify the bicycles reported as stolen in a collection of bicycles with the help of a reader, but it would also make it easier to find your own bicycle in a large bicycle parking lot.

Since the identification features can be determined wirelessly using a simple electronic reader over a distance that depends on the performance of the reader, a kind of black box recording of the last few minutes before a traffic accident would be possible with all those involved in the accident. To do this, the functions of the vehicle assistance systems already installed in many automobiles, for example, would have to be expanded so that the radio tags of neighboring objects are continuously and cyclically determined and temporarily recorded.

A similarly designed arrangement, which is however suitable for very large distances, is used in 25 shown. The large number of retroreflectors causes a very significant interaction with the radar system. This arrangement is particularly suitable for objects that are far away but whose surface is aligned with the radar system. For example, own containers stacked on top of one another can be distinguished from other containers and counted or confirmed.

A very effective way of combining three-dimensional retroreflectors with planar labels is in 26 shown. There, a planar, multifunctional label structure (4) is attached to a circular assembly support (22), for example. The resulting additional mounting surfaces can be retroreflective structures, as in connection with the explanations for 12 have been discussed can also be mounted. These three-dimensional retroreflectors (23) are first grouped to match the free areas and then mounted on the areas not occupied by the planar multifunctional label structure (4) on the mounting support (22), for example by gluing.

The related to the 12 The cube-shaped structures discussed above, as three-dimensional retroreflectors in connection with the two-dimensional, planar retroreflectors presented here, have the disadvantage that, for the frequency range used for radar systems, they would either have to be enlarged by scaling to such an extent that the dimensions are no longer suitable for flat installation, or that they remain as small as is required for optical applications, and as a result the reflecting surface that becomes effective cannot be used optimally.

The one here in is much better suited 27 presented reinvented structure consisting of thin metal plates. This form of retroreflectors is based on bodies constructed of metal plates assembled in connection with marine applications for visualization on the radar system of small non-metallic boats in rough seas.

The dashed contour in 27 shows the octahedron radar reflector with eight triangular corner reflectors in the so-called quadruple position, which is known in connection with radar systems in the nautical industry.

However, even the dimensions of these highly effective retroreflectors, scaled according to the significantly shorter wavelength in the range of 4 mm of the radar systems used for road traffic, would still be too large for the requirements desired here. Because related to the integration of planar retroreflecto ren, however, only a one-sided, namely frontal reflection is required, the entire lower part of the octahedron with the edge length Q according to the 27 omitted. As a result, there is no longer any retroreflection towards the rear. However, this is also the case with the planar retroreflectors anyway. Therefore, both forms are now compatible in terms of their reflection behavior.

Thus, after removing the lower part of the octahedron radar reflector, the in 27 shown lateral silhouette of a pointed cone or pyramid consisting of two metal plates crossing in the middle, which are on another square metal base plate.

In a further modification step, this geometric dimension is now also further reduced in order to further increase the degree of compatibility with the planar retroreflectors.

It has been found that as a compromise between performance and geometric dimensions, the height T from the center plate to the top can also be reduced by a third of the original height to flatten the entire assembly without compromising the function or effectiveness of the Radar retroreflector more than 20% limit. This is how one arrives at these modifications of the well-known octahedron radar reflector, as it is shown in 27 shown in solid and dashed to a still highly efficient but now very compact spatial retroreflector (24). The solid lines in 27 show the contour of this more compact construction after the modification according to the invention.

A multitude of such a single element as in the 27 shown with solid lines, is now arranged continuously with its square base plates edge to edge to form a planar structure. On the free mounting surfaces, for example, of a round mounting bracket (22) as shown in 26 is shown, the in 27 Single retroreflective element shown in solid lines in plurality with its square base surface of edge length Q, similar to that in 26 shown, as additional three-dimensionally realized retroreflectors, arranged on a mounting support and fastened, for example, by gluing or otherwise. A radar beam (R) coming directly from the front is shown in accordance with 27 with the entire metal surface totally reflected. A radar beam (S) incident from the side is shown in accordance with 27 also reflected almost at full strength with only a slight lateral offset. Overall, the in 27 structure of the compact spatial retroreflector shown, with the same volume as that associated with 13 discussed structure, significantly more effective, especially when they are as in 26 shown is combined with other planar RFID radar tags.

the 28 shows an example of a sectional drawing to explain a combined retroreflector. Since radar beams easily penetrate the dielectric of optical retroreflectors, both versions, namely optical retroreflectors on the one hand and retroreflectors suitable for radar systems on the other hand, can be mounted together in a common housing. the 28 shows schematically how this can be realized. Both planar multifunctional label structures (4) and three-dimensional retroreflectors (23) are mounted on the base plate in a mounting support (22). If the expanded functionality made possible by the planar multifunctional label structures (4) is not desired, then this does not have to be installed in order to save costs. Instead, the area freed up as a result can be used for the installation of additional three-dimensional retroreflectors if, for example, only backscattering for presence detection is desired. The optical retroreflectors (25) are, as in 28 shown, formed as a cap and mounted above the spatial retroreflectors (23). This allows for a very flat design and this combined retroreflector can be worn on clothing like a button as a safety accessory, for example, or attached to an object you are carrying, in order to provide a clear signal both in the headlights and in the traffic radar system of a vehicle produce reflection. The additional optical marking of bicycles with reflectors, front reflectors, pedal and spoke reflectors is already mandatory today. Technically, it would not be a problem to use the respective optically acting reflectors in accordance with in 28 to supplement the principle shown with retroreflectors so that the bicycles can also be recognized more clearly by the radar systems in the automobiles. The spoke reflectors that are already present can be easily replaced by such combined retroreflectors, which are designed as optical reflectors, which, however, also, as in 28 shown, have radar retroreflectors in common housing, replace. Similarly, combined front retro-reflectors or combined rear retro-reflectors can either be combined with existing retro-reflectors or fitted in addition. In addition, bicycles can be provided with a unique identification. This would also significantly alleviate the detection problem in connection with autonomously controlled vehicles and would make a further contribution to traffic safety security, especially for future developments.

the 29 shows an additional modification of the radio tag according to 13 . In the 13 The slot line resonators (10) shown have a high electrical quality and a stray field that is narrowly limited to the narrow air gap in the strip. This results in a very low degree of coupling with spatially adjacent further slot line resonators. There is therefore no superimposition of the respective resonant frequencies, as is the case, for example, with band filters from coupled resonant circuits. As a result, they enable sharply delimited resonance frequencies that are significantly recognizable in a broadband reception spectrum, from which the geometrically stored information can be reliably reconstructed with the help of suitable UWB readers.

Due to the low stray field, however, coupling to the reading devices is not possible over large distances.

In order to significantly increase the possible read range, a modification of the structure of the slot line metallization (9) is required 29 expedient.

The multi-frequency half-wave dipole (5) is, as to 16 explained, including in resonance at an exemplary selected frequency of 2.42 GHz. It also resonates at double, triple, quadruple, etc. frequency if the electrically effective length corresponds to a multiple of half the wavelength at the lowest resonant frequency. Therefore, the multi-frequency half-wave dipole also acts as an antenna device in frequency bands that are approved for the operation of UWB readers.

Since the multi-frequency half-wave dipole (5) is an open strip line structure with an enlarged stray field due to the widening of one end of the line, the interaction of this multi-frequency half-wave dipole (5) with the electromagnetic field of the UWB reading devices is significantly greater than with the slot line resonators with their limited stray field is the case. the 29 shows clearly how part of the lateral stray field of the multi-frequency half-wave dipole (5) is coupled into the respective slot line resonators.

The slot line metallization (9) together with the slot line resonators (10) is brought up to the metallization of the multi-frequency half-wave dipole (5) except for a gap in the metallization with a width of about 0.2 mm. In contrast to the illustration in Fig 13 now, however, in the immediate vicinity of the multi-frequency half-wave dipole (5) not short-circuited by the slot line metallization (9), but they are now open there, ie open-circuited. This results in an intensive coupling of the stray field of the multi-frequency half-wave dipole (5) on the one hand and the stray field of the respective slot line resonators on the other.

The multi-frequency half-wave dipole (5) thus acts like an additional receiving and transmitting antenna for the respective slot line resonators. This improves the interaction with the UWB readers and significantly increases the possible reading range. To explain the principle are in the 29 only 4 slot line resonators shown schematically. This should only keep the effort for the drawings low and the respective slot line resonators should still be clearly recognizable in the drawing. In the practical implementation of the RFID radar labels, a higher number of slotted line resonators is possible without any problems, for example to enable the information content of a typical BATR code.

Reference List

(1)

Oberseitenmetallisierung

(2)

Substrat

(3)

Unterseitenmetallisierung

(4)

planare multifunktionale Etikettenstruktur

(5)

multifrequenter Halbwellendipol

(6)

Montagegrube

(7)

multifrequenter Viertelwellenresonator

(8)

dielektrischer Freiraum

(9)

Schlitzleitungsmetallisierung

(10)

Schlitzleitungsresonator

(11)

Durchmetallisierung

(12)

Spalt

(13)

Diode

(14)

Chipmodul

(15)

Chipmodulbasis

(16)

Montagebereich

(17)

Zuleitungsfixierung

(18)

ASIC

(19)

Erdungsleitung

(20)

Versorgungsleitung

(21)

Klebstoff

(22)

Montageträger

(23)

räumliche Retroreflektoren

(24)

kompakter räumlicher Retroreflektor

(25)

optische Retroreflektoren

Verzeichnis der in den Figuren verwendeten Buchstaben

A

Punkt am leerlaufenden Ende des multifrequenten Viertelwellenresonators (7)

B

Punkt am Ende des multifrequenten Halbwellendipols (5), welches an der Montagegrube (6) liegt

C

Punkt am Ende des multifrequenten Halbwellendipols (5), welcher der Montagegrube (6) gegenüber liegt

G

Punkt am kurzgeschlossenen Ende des multifrequenten Viertelwellenresonators (7) an der Montagegrube (6)

H

Höhe des dielektrischen Substrates

L

Länge einer Struktur der Oberseitenmetallisierung (1)

P

Trapezlänge der verkürzten Tetraederstruktur

Q

Kantenlänge eines Oktaeders

R

frontal einfallender und reflektierter Radarstrahl

S

seitlich einfallender und reflektierter Radarstrahl

T

verbleibende Tetraederhöhe nach Verkürzung

W

Weite einer Struktur der Oberseitenmetallisierung (1)

(1)

top metallization

(2)

substrate

(3)

underside metallization

(4)

planar multifunctional label structure

(5)

multi-frequency half-wave dipole

(6)

assembly pit

(7)

multi-frequency quarter-wave resonator

(8th)

dielectric free space

(9)

slotline metallization

(10)

slot line resonator

(11)

plating through

(12)

gap

(13)

diode

(14)

chip module

(15)

chip module base

(16)

assembly area

(17)

cable fixation

(18)

ASIC

(19)

ground wire

(20)

supply line

(21)

adhesive

(22)

mounting bracket

(23)

spatial retroreflectors

(24)

compact spatial retroreflector

(25)

optical retroreflectors

Index of the letters used in the figures

A

Point at the open end of the multi-frequency quarter-wave resonator (7)

B

Point at the end of the multi-frequency half-wave dipole (5), which is located at the mounting pit (6).

C

Point at the end of the multi-frequency half-wave dipole (5), which is opposite the mounting pit (6).

G

Point at the shorted end of the multi-frequency quarter-wave resonator (7) at the mounting pit (6)

H

Height of the dielectric substrate

L

Length of a structure of the top metallization (1)

P

Trapezoidal length of the truncated tetrahedron structure

Q

edge length of an octahedron

R

Frontal incident and reflected radar beam

S

laterally incident and reflected radar beam

T

remaining tetrahedron height after shortening

W

Width of a structure of the top metallization (1)

bibliography

• [01] DE000001129192A 1129192 of May 10, 1962, Applicant: Dunlop Rubber Company Ltd., London.
• [02] WO002017055516A1 , International Registration WO 2017/055516 A1 from April 6, 2017, applicant: Erich Utsch AG, Siegen.
• [03] Hashemi, A.; Sarhaddi, A.H. and Emami, H.: "A Review on Chipless RFID Tag Design", in: Majlesi Journal of Electrical Engineering, Vol.7, No.2, June 2013.
• [04] Vena, A.; Perret, E.; Tedjini, S.; Tourtollet, E.P.; Delattre, A.; Garet F. and Boutant, Y.: « Design of Chipless RFID Tags Printed on Paper by Flexograhy », in: IEEE Transactions on Antennas and Propagation, Vol. 61, No. 12, Dec 2013
• [05] Tedjini, S.: "Chipless RFID, State of the art & current Developments", WIPE COST IC 1301, International Spring School on Electromagnetics and emerging technologies for pervasive applications: Internet of Things, Health and Safety, 18 - 20 April 2016, Bologna, Italy.
• [06] W0002017140628A1 , International Registration WO 2017/140628 A1 dated 24.8.2017, applicant: Telensa Limited, London.
• [07] EP000003210587A1 , European Patent Application EP 3 210 587 A1 from August 30, 2017, applicant: Novartis AG, Basel.
• [08] Koster, Norbert H L .Feb.1984.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 1129192 A [0009]
• WO 2017055516 A1 [0011]
• WO 2017140628 A1 [0016]
• EP 3210587 A1 [0017, 0139]
• DE 000001129192 A [0139]
• WO 002017055516 A1 [0139]
• WO 2017/055516 A1 [0139]
• WO 002017140628 A1 [0139]
• WO 2017/140628 A1 [0139]
• EP 000003210587 A1 [0139]

Claims (6)

Multifunctional RFID radar label system, with a large number of resonators applied to a carrier material, characterized in that a combination of both slot line resonators (10) and stripline resonators, which on the one hand as a multi-frequency half-wave dipole (5) and on the other hand are designed as a multi-frequency quarter-wave resonator (7), the slotted line resonators having different resonant frequencies which can be determined wirelessly by a remote reading device and whose frequency pattern contains digital information, the stripline resonators being designed as a half-wave dipole (5). , at the low specified operating frequency, a dipole which is open on both sides and has an electrically effective length of half a wavelength at the low specified operating frequency represents and at the high specified operating frequency a dipole which is open on both sides and has an electrically effective length of more than twenty times half the wavelength at the upper specified operating frequency and where the stripline resonators, which are designed as quarter-wave dipoles (7), represent one on both sides at the low specified operating frequency represents an open-circuit dipole with an electrically effective length of one-quarter wavelength at the low specified operating frequency and at the high specified operating frequency represents a double-ended open-circuit dipole with an electrically effective length of more than ten times the quarter-wavelength at the upper specified operating frequency. Multifunctional RFID radar tag system claim 1 , characterized in that the multi-frequency half-wave dipole (5) and the multi-frequency quarter-wave resonator (7) act together as a resonant chaff for an FMCW radar system operated at the high intended operating frequency and thereby cause increased interaction with the radar system. Multifunctional RFID radar tag system claim 1 , characterized in that there is also a mounting pit (6) for receiving a chip module (14) on a planar multifunctional label structure (4) in the carrier substrate and the multi-frequency half-wave dipole (5) and the multi-frequency quarter-wave resonator (7) together chip module (14) receive the operating energy required from the feed field of a reading device operated at the low intended operating frequency and feed it to the chip module (14), the activated chip module (14) transmitting the information stored in it to the reading device with the aid of absorption modulation. Multifunctional RFID radar label system according to one of the preceding claims, characterized in that the planar multifunctional label structure (4) is mounted on a mounting support (22) of sufficient size and that a plurality of non-planar, So spatial retroreflectors (23) is arranged, which is suitable depending on the respective geometric dimensions for reflecting either radar signals, lidar signals or optical light beams. Multifunctional RFID radar tag system claim 4 " characterized in that the spatial retroreflectors (23) produced by shortening the structure are compact spatial retroreflectors (24). Multifunctional RFID radar label system according to one of the preceding claims, characterized in that the planar multifunctional label structure (4) is mounted on a mounting support (22) of sufficient size and that laterally around the planar multifunctional label structure (4) a plurality of planar metal structures is arranged, wherein the respective planar metal structures have a top (1) and a bottom (3) which are galvanically isolated from one another by a substrate (2) and wherein the planar metal structures of the top (1) are shaped so that they are at the Operating frequency of an FMCW radar system used as intended for remote detection of the planar multifunctional label structure (4) resonates, thereby acting as resonant chaff and thereby causing increased interaction with the radar system.

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