DE102016213330A1 - Method for locating a mobile object and transponder for this purpose - Google Patents

Abstract

The invention relates to a method for locating a moving object (1), in which a chipless, passive transponder (3, 31), which is coded by a plurality of subareas (6, 7, 8, 9) having a different polarimetric property, is detected by a radar station (3). 5) is irradiated with polarized electromagnetic waves, the transponder (3, 31) or the radar station (5) being arranged on the object (1), the radar station (5) detecting the waves reflected at the transponder (3, 31) in that a polarization-coded image is generated from the reflected waves and the transponder (3, 31) is recognized on the basis of the polarization-coded image, the object (1) is identified on the basis of the recognized transponder (3, 31) and identified on a current position of the identified object (1). is closed. Furthermore, a corresponding transponder (3, 31) is indicated.

Description

The invention relates to a method for locating a moving object, wherein a chipless, passive transponder is used, which is encoded by a plurality of sub-areas with different polarimetric property, and in which the transponder is identified by means of radar technology. The invention also relates to a passive, chipless transponder which is suitable for the method for locating a moving object.

RFID (Radio Frequency Identification) systems with a reader or interrogator and a transponder to be interrogated are used in a wide variety of applications. Transponders (also referred to as "RFID tags") can basically be subdivided into active, semi-passive and passive systems on the basis of their structure, as described, for example, in US Pat S. Preradovic, NC Karmakar, I. Balbin; "RFID Transponders", IEEE Microwave Magazine, October 2008, pages 90-103 , is described.

Furthermore, a distinction is made between chipless and chip-based transponders, with active and semi-passive systems generally using chip-based transponders. However, passive transponders may also have semiconductor chips for storing information (see, for example, US Pat EP 1 993 168 A2 ). Disadvantages of chip-based transponders are their comparatively high cost and their susceptibility to external influences such as high or very low temperatures, mechanical shock and vibration, which is a consequence of the sensitivity of the semiconductor devices used and the associated construction and connection technology. Another disadvantage of chip-based transponders is the need for a power supply for the supply of semiconductor chips and active chip-based transponders, the life limited by a battery life.

Chipless transponders, in turn, can be split into transponders for time domain based (TDR), frequency based (FDR) or image based systems.

Due to their functionality, TDR systems use SAW (surface acoustic wave) transponders or microwave transponders. Microwave transponders encode their information in their impulse response, requiring long delay times on the transponder. To realize these delay times, large geometric structures must be used, whereby increased losses and, in many cases, dispersion may occur. In SAW transponders, a required delay time can be achieved by a wave conversion of electromagnetic to acoustic waves, since acoustic waves have much slower propagation speeds. The information can be encoded in SAW transponders analogous to microwave-based systems, as for example in the WO 2000 039 604 A1 is disclosed. However, wave conversion produces high loss, which reduces the range of such systems.

FDR systems evaluate a frequency response of a transponder, mostly resonant structures are used, as for example in the WO 2011 098 719 A4 or in the WO 2009 126 999 A1 is described. Resonances of structures of the transponder must be separable from each other. There are approaches to perform a separation of the resonances based on the frequencies or spatially.

For spatial separation, imaging systems can be used; see for example M. Zomorrodi, NC Karmakar: "Image-based Chipless RFID System with High Content Capacity for Low Cost Tagging", IEEE International Microwave and RF Conference, pp. 41-44, 15-17 December 2014 , In this case, the evaluation of the polarization of the radiated and received electromagnetic waves is used to reduce interference by, for example, Mehrwegausbreitungen. Another application of polarization in RFID tags is the so-called polarisatinsmultiplex, in which two data channels are separated by means of polarization, as for example in MA Islam, NC Karmakar: "Design of a 16-bit Ultra Low Cost Fully Printable Slot-Loaded Dual-Polarized Chipless RFID Tag", Proceedings of the Asia-Pacific Microwave Conference, pages 1482-1485, 5-8 December 2011 or in the WO 2013 096 995 A1 is disclosed. In addition, polarization can provide amplitude modulation to FDR tags, such as A. Vena, E. Perret, S. Tedjni: "A Depolarizing Chipless RFID Tag for Robust Detection and Its FCC Compliant UWB Reading System", IEEE Transactions on Microwave Theory and Techniques, Vol. 61, 2013, No. 8, p. 2982 -2,994 , is disclosed. An example of information coding by means of polarization and phase states with the aid of resonant, planar antenna structures is shown in FIG US 2005 0280504 A1 disclosed.

The use of chipless RFID transponders is now very diverse, in particular, this is the common barcode to be replaced, as this has several disadvantages such as unreadability in case of contamination or weathering. Furthermore, such a transponder for locating or tracking objects (see, eg DE 197 098 47 A1 or DE 20 2010 018 131 U1 ) and as a sensor for measuring temperature, pressure or moisture (see, eg WO 199 013 495 A1 ) be used.

However, a disadvantage of chipless RFID systems is their high bandwidth required, which is necessary for high data capacity in both TDR and FDR systems. The bandwidth is not adjustable arbitrarily due to legal regulations. The data capacity is severely limited in such systems. For example, in microwave-based TDR systems, data capacities of 16 bits and in FDR systems data capacities of up to 35 bits can be achieved. For SAW transponders, data rates of 96 bits are commercially available.

In this case, the production of SAW transponders can not be realized inexpensively. In addition to elaborate structuring special materials such as LiNbO ₃ must be used. FDR transponders must use materials whose permittivity is well known. For TDR transponders intended for microwave systems, low-dispersion and low-loss materials must be used. The materials and structures of the described chipless RFID transponders have hitherto also not been suitable for use at high temperatures. Another disadvantage is the short range of all previous RFID systems with chipless passive transponders.

Polarimetry is generally used in a variety of radar applications, and in particular in high-resolution imaging systems. Polarization agile imaging systems are used in remote sensing (see eg WO 2015 041 295 A1 ) or in safety technology (see J. Adametz, L.-P. Schmidt: "Thread object classification with a close range polarimetric imaging system by Means of H-alpha decomposition", European Radar Conference, pages 77-80, 9 to 11 October 2013 ) used. In all cases, polarimetric scatter information from targets is used to more accurately classify or identify unknown objects. For this purpose, appropriate evaluation algorithms are known in the literature. In the field of radar imaging, the region of interest or the object to be analyzed is often scanned, scanned, run or run through SAR (Synthetic Aperture Radar), and an image is calculated by means of special reconstruction algorithms, as described, for example, in US Pat EP 2 767 849 A2 is disclosed.

When a SAR scan is performed fully polarimetrically, with the target or observed object scene sequentially illuminated with at least two differently polarized, preferably two orthogonally polarized electromagnetic waves, and the polarization of the scattered or reflected waves recorded, after SAR processing based on the polarimetric information, a classification of the existing objects are performed. In remote sensing, this way, as in T. Moriama, S. Uratsuka, Y. Yamaguchi: "A Study of Extraction of Urban Areas from Polarimetric Synthetic Aperture Radar Image," IEEE Geoscience and Remote Sensing Symposium, pp. 703-706, September 20-24, 2004 described, very well populated by wooded areas. In safety engineering, the fully polarized SAR scan makes it possible to distinguish between different sources of danger. These delimitations or categorizations can be significantly more difficult with a conventional radar system, which does not have the full polarimetric scatter information. Basically, in a fully polarimetric data set, the complete scattering or reflection information of a target is included, which can be used for an optimized classification or identification.

In the German patent application not yet disclosed at the time of the present application DE 10 2015 117 712 a method for imaging polarimetry is described, in which a chipless, passive transponder, which has a plurality of sub-areas with different polarimetric property, is irradiated by radar radiation with at least two differently polarized waves, a polarization-coded image of the transponder is generated based on the radar radiation reflected thereon, and the different sub-areas of the transponder are recognized in the polarization-coded picture by means of their at least one polarimetric property. For this purpose, a corresponding passive, chipless radar transponder is described which has at least two partial surfaces with different polarimetric properties.

The transponder is encoded via the type and sequence of the subareas. The method of imaging polarimetry can also be regarded as a method for reading the chipless, passive transponder. The specified transponder is used as an identification tag or tag. He has neither a semiconductor device nor an electrical energy storage. The transponder can also be referred to as a radar-sensitive transponder or radar transponder. The sub-areas of the described transponder having a different polarimetric property generate different backscatter patterns, which can be differentiated and unambiguously assigned with the aid of known polarimetric radar methods.

The Indian DE 10 2015 117 712 specified transponder or the corresponding method for its identification is insensitive to Pollution and weathering. The transponder itself can also be used at very high temperatures, using, for example, temperature-resistant materials such as ceramics. To produce a desired polarimetric property of a partial surface, for example, a regularly shaped structure is introduced. Even irregular structures are possible, provided that their polarimetric backscatter behavior, ie the way in which they change polarization upon reflection, is known. A regularly shaped structure may, for example, have a plurality of mutually parallel longitudinal grooves. The grooves can be introduced with a predetermined angular orientation. By adjusting the angular orientation, different partial images can be generated. On the receiver side, this allows a clear inference to the subareas and thus the unambiguous identification of the transponder. This ensures the transmission of information between the transponder and the radar station or reader via polarimetric imaging. This allows a high number of possible information states per transponder, in particular in fully polarimetric methods. A high data capacity is achievable in particular by a high amount of partial areas that can be accommodated in a small area. A transponder with more than 128 bits can be realized.

The invention has for its object to provide a deployment scenario for a passive, chipless radar transponder and for this application scenario, a suitable structure of the transponder.

This object is achieved according to the use scenario according to the invention by a method for locating a moving object, wherein a chipless, passive transponder, which is encoded by a plurality of sub-areas with different polarimetric property is irradiated by a radar station with polarized electromagnetic waves, wherein the transponder or Radar station is arranged on the object, wherein detected by the radar station, the waves reflected at the transponder, wherein from the reflected waves generates a polarization-coded image and the transponder is recognized by the polarization-coded image, and wherein based on the detected transponder identifies the object and on a current position of the identified object is closed.

The invention is based in a first step of making the location of the moving object by reading a radar barcode. The reading of a radar barcode by radar technology is a robust and against external influences such as temperature and pollution comparatively insensitive process. In a second step, the invention provides to implement the radar barcode by a chipless, passive transponder, which several sub-areas with different polarimetric property is encoded. The reading of the radar barcode is done here by identifying the faces on the basis of their different polarimetric properties, which is based on the imaging polarimetry.

The radar transponder and thus the locating procedure are insensitive to external pollution. For use in very low or very high temperature areas, appropriate materials for the transponder, such as ceramics, metals or alloys, are to be used.

Imaging polarimetric radar methods are basically known. For identification of the transponder on the basis of its specific partial areas with different polarimetric properties, an imaging, fully-polarimetric MIMO (Multiple Input Multiple Output) radar method is particularly suitable, wherein antenna arrays are used for transmitting and receiving the radar radiation or the waves transmitted and received in the corresponding wavelength range. Advantageously, a digital beamforming with parallel data recording on the receiver side is used here. The antenna array enables a fully polarimetric measurement. In particular, in this case each antenna element of the antenna array is designed to emit electromagnetic waves with selectable polarization from two orthogonal polarization directions.

The polarimetric imaging radar method is based on the decomposition of an electromagnetic wave with any direction of polarization in two orthogonal components, which are usually labeled with horizontal (H) and vertical (V). The radar station, ie the transmitting and receiving station or the corresponding transmitting and receiving antenna, must therefore be able to transmit and receive horizontally and vertically polarized electromagnetic waves. For a fully polarimetric imaging, objects with different polarimetric properties are identified via their portions of backscattered or reflected electromagnetic radiation in horizontal and vertical polarization with respect to the emitted electromagnetic radiation in horizontal or vertical polarization. In this case, the four combinations HH, HV, VH and VV are present, wherein the first index denotes the polarization direction of the received and the second index the polarization direction of the emitted electromagnetic radiation.

For example, a planar surface has a constant backscatter behavior. An incident wave is simply reflected back, with no change in polarization direction. Consequently, portions in the backscattered radiation are found only in the combinations HH and VV. For multiple reflections or in the case of dipole elements, however, cross components can result. Furthermore, phase jumps are possible. In polarimetric imaging, dipole structures or double mirror elements can be distinguished from planar surfaces. In addition, with respect to the return reflection, a dependence on the angular orientation of the dipole elements or the multiple mirror is added. Accordingly, such structures or dipole elements that are aligned at different angles to each other can also be distinguished from one another in polarimetric imaging.

For polarimetric imaging, SAR algorithms or iSAR algorithms are preferably used, in which a relative movement between the radar station and the observed object is used to construct a synthetic aperture of a large antenna, whereby the spatial resolution is significantly improved (SAR = "Synthetic Aperture Radar ", ISAR =" inverse Synthetic Aperture Radar ").

Subareas with different polarimetric properties produce different and so far distinguishable backscattering or reflection patterns. The partial area is preferably a surface of the transponder. In particular, the surface may also be assigned underlying volume regions of the transponder in order to form its polarimetric property. For dipoles, a non-volume partial area may be planar, e.g. By conductor pieces, be realized.

The polarimetric imaging radar method preferably comprises electromagnetic radiation in a range between 1 GHz and 1 THz. Electromagnetic radiation in a range between 10 GHz and 100 GHz is advantageously used. The irradiation takes place within the scope of the invention, spatially or object-fixed. It can also be carried out preferably in a time division (TDM) or in a frequency division multiplexing (FDM) mode.

The respective subareas of the transponder are advantageously detected in the polarization-coded image as sub-images and identified, for example, by methods of object recognition. Information is derived from the recognized subareas or partial images, for example by using the subareas as information carriers analogously to bits having n (n> 1) possible states. The information of the transponder is thus encoded in its polarimetric backscattering or reflection behavior. Since the backscattering behavior of the partial surfaces used is defined, they can be searched and classified according to their properties during the evaluation. Each existing, previously defined backscattering behavior of a partial surface, which is distinguishable from the backscattering behavior of other partial surfaces, describes a possible information state. By arranging a plurality of subareas, information can thus be stored on the transponder.

In a preferred embodiment of the invention, the transponder is recognized from the polarization-coded image by analytically calculating the polarimetric property of at least one partial surface. This can be done, for example, by applying analytical formulas to a partial image and comparing a result of the calculation with a predetermined reference result.

In a further preferred refinement, the transponder is identified on the basis of an image comparison of at least one partial image of the polarization-coded image with at least one reference image. This is advantageously carried out by means of object recognition methods, the reference image in particular corresponding to a polarization-coded image of an object with a corresponding polarimetric property. Expediently, corresponding reference images are respectively deposited for the partial surfaces of known polarimetric property used and defined on the transponder.

Advantageously, the polarization-coded image is subjected to a Pauli decomposition and the transponder is recognized from at least one pauli-decomposed image on the basis of at least one polarimetric property of a partial surface. In particular, a pauli-decomposed image is an image that has been generated from an original fully polarimetric image by means of a Pauli decomposition. In Pauli decomposition, the full polarimetric scattering or reflection information at each pixel or image is split into the scattering processes of simple reflection, double reflection, and volume scattering. A Pauli decomposed image encodes the reflection processes, such as single reflection, double reflection, and volume scattering, into e.g. colored picture. This refinement has the advantage that different partial surfaces can be distinguished and recognized particularly well and reliably. For example, at least one patch can be recognized by evaluating only a pauli-decomposed polarization-coded frame or field (e.g., representing simple reflection). For example, at least one subarea can be recognized by means of an evaluation of several pauli-decomposed polarization-coded images or partial images.

For evaluating the polarimetric data, apart from the Pauli decomposition or in addition to the Pauli decomposition, another suitable decomposition algorithm for the fully polarimetric image data can also be selected.

Advantageously, a transponder is used which comprises at least one partial surface with a polarimetrically active structure. In addition, a partial surface with a smooth surface and / or of a homogeneous material can be used for the transponder, which accordingly has no polarimetrically active property. Nevertheless, in the sense of the present invention, such a smooth partial surface differs in its polarimetric property (namely, the no polarization rotation) from a partial surface which comprises a polarimetrically active structure. A polarimetric structure of the patch is a modification of the surface, e.g. by dipole elements, and preferably a three-dimensional surface form, wherein each of the polarimetric properties are known. It is sufficient if the structure occurs exactly once on a partial surface, as long as the structure reflects sufficiently. By way of example, such a structure may comprise elevations and / or depressions, which in particular run parallel. The polarimetrically effective structure comprises in particular reflective geometries whose polarimetric backscattering behavior can be produced in a defined manner, for example wires acting as dipoles or milled structures such as double or triple mirrors. Preferably, all polarimetrically active structures and / or all subareas as such are antenna-less, ie without wires and dipoles.

Suitable materials for the transponder are plastics, ceramics, metals or alloys. The choice of materials depends on the particular application scenario of the transponder.

In a further expedient embodiment, a transponder is used which comprises at least one partial surface with a polarimetrically active material. In this context, reference is made in particular to the fact that materials as such have polarimetrically active properties. The partial surfaces may be formed, for example, as a sequence of polarimetrically active materials.

The transponders used preferably have a dimension in the range of a few millimeters to a few tens of centimeters. The partial surfaces are corresponding subunits for this purpose. The faces may differ in size. But they can also each have the same size or area.

In a preferred variant, the object is assigned a transponder extending along a longitudinal axis, the partial surface of which is in each case formed as part circumferential surfaces that surround the longitudinal axis. In this way, the transponder can be detected and identified on the moving object from every spatial direction. The backscattering behavior of the transponder is clearly defined from each spatial direction with respect to its longitudinal axis. Advantageously, the transponder is essentially given as a cylinder extending along the longitudinal axis.

Expediently, the transponder is assembled along the longitudinal axis from disk-shaped sub-segments which form the circumferential partial circumferential surfaces. The partial surfaces or the structures produced thereon are distinguished by polarimetric measuring methods. Since the combination of the sub-segments and thus the location-dependent polarimetric backscattering or reflection behavior of the transponder can be set as desired, information in this way can be stored on the transponder in a simple manner. Preferably, several sub-segments are combined with different polarimetric property or different structures to the transponder. The individual partial surfaces or structures can occur more than once. This results in a polarimetric radar barcode which, unlike optical barcodes, can be read from all directions. Depending on the application requirements, the number of sub-segments may vary. In a preferred embodiment, between four and sixteen subsegments are assembled to achieve data capacities of more than 64 bits on the transponder, depending on the application. The data capacity is determined by the number of subsegments or subareas as well as by the number of possible polarimetric properties.

The circumferentially detectable radar transponder is expediently placed on a moving object. Possible objects for use are preferably vehicles, among others motor vehicles and thereof, for example, lift trucks or any other vehicles, such as mobile robots, construction vehicles, industrial trucks, hoists, rack conveyors, rail, air and water vehicles. However, movable objects can also be transported goods, in particular containers, or packaged goods such as cartons, etc.

The radar stations used for localization and decoding are installed or installed at known locations, eg on walls of buildings. Suitable radar stations are, inter alia, conventional automotive radar systems, wherein Each radar system in a preferred variant allows fully polarimetric data acquisition.

As already mentioned above, the transmitting and receiving antennas used are preferably arranged in an array. The size of the array determines, in addition to the wavelength of the system, the spatial resolution of the radar system. Depending on the range and size of the partial areas or the sub-segments of the transponder, the number of antennas and arrangement is adjusted so that a spatial separation of the sub-areas of the transponder using radar imaging is possible. For the position determination in the horizontal direction, the transponder, which is arranged on the moving object, moves between several individual measurements or decoding processes at the radar station. This allows the generation of an inverse synthetic aperture (iSAR), which allows a position determination in the direction of travel of the object. This allows a position determination and identification of the mobile object. The identification of the moving object is carried out by the evaluation of the radar imaging of the reader. Based on the position of the reader, the identification of the transponder and the position determination via the iSAR method, a 3D localization of a clearly defined, mobile object is possible.

In another likewise advantageous embodiment variant in which, for example, radar systems can not be mounted outside the movable object, the above-described principle is inverted. Preferably, the radar station is then assigned to the object, wherein, for example, on walls of a building, a planar transponder is used whose partial surfaces are arranged alongside one another along a longitudinal axis. The radar station in this case advantageously comprises an omnidirectional antenna, a circular antenna array or a rotating antenna. The movement of the radar station relative to the transponder generates a synthetic aperture (SAR), which in turn is used to decode the radar barcodes and locate the radar station. The polarimetric codes form landmarks that can be uniquely assigned to a position in space. In principle, it is possible, in certain scenarios (for example on a freestanding shelf), to use a transponder with peripheral partial circumferential surfaces, for example a cylinder. For the majority of applications, however, other geometric and in particular planar shapes are to be preferred, for example, to use several tiles of sufficiently reflective material having the desired polarimetrisch separable properties.

The mobile radar station method is particularly preferable when the location of the mobile object must be in a large-scale environment. Because even in this case only one radar station per monitored object is necessary. The cost of a radar station is significantly increased compared to the cost of a transponder. The transponder is maintenance-free compared to a radar station and robust against environmental influences. In particular, the transponders can be easily manufactured in large numbers for industrial environments.

Preferably, a vehicle, in particular a motor vehicle, is used as the object. The invention is particularly suitable for monitoring transport or stacking vehicles, for example in large warehouses or the like. In particular, the invention makes it possible to operate a warehouse autonomously by knowing the appropriate stacking vehicles themselves at any time about their specific position.

The stated object is also achieved by a passive, chipless transponder which extends along a longitudinal axis and is encoded by a plurality of sub-areas with different polarimetric property, wherein the sub-areas are arranged successively sequentially along the longitudinal axis. In other words, all partial surfaces are arranged successively with respect to the longitudinal axis. Such a transponder is identifiable when used on a moving object from any direction. The movement of the object can be used in particular for iSAR methods. On the other hand, when the transponder is fixedly mounted on a wall of a building or the like, the movement of a radar station mounted on the moving object is used for performing an SAR method. Accordingly, for a mobile use of the transponder, its partial surfaces are preferably designed in each case as partial circumferential surfaces that surround the longitudinal axis. Advantageously, in this case the transponder along the longitudinal axis of disk-shaped, in each case the peripheral part of the circumferential surfaces forming sub-segments composed. The transponder used for stationary use is expediently designed to be flat. The transponder preferably has at least one partial area with a polarimetrically effective structure and / or at least one partial area with a polarimetrically active material.

The advantages described for the method for locating and its advantageous developments can be analogously transferred to the transponder and its developments.

Embodiments of the invention will be explained in more detail with reference to a drawing. Showing:

1 schematically a vehicle with a mobile radar transponder,

2 correspond to a mobile radar transponder 1 in detail and

3 schematically a forklift with mobile radar station and stationary radar transponder.

1 schematically shows a moving object 1 which, for example, as a motor vehicle 2 is trained. For locating the moving object 1 This is a three-dimensional transponder 3 assigned, which carries a readable from any direction radar barcode. At various points of the room to be monitored, for example, on a wall 4 a building radar stations 5 arranged. The radar barcode of the transponder 3 is by means of a plurality of partial surfaces 6 . 7 . 8th . 9 formed along a longitudinal axis 10 which is perpendicular to a direction of travel of the motor vehicle 2 is aligned, arranged successively. The exact structure of the three-dimensional transponder 3 is out 2 seen.

Accordingly, the transponder includes 3 four partial surfaces 6 . 7 . 8th . 9 , which each form circumferential partial circumferential surfaces. The transponder 3 is formed substantially cylindrical overall. The partial surfaces 6 . 7 . 8th each carry polarimetrically different effective structures 16 . 17 . 18 , The polarimetrically effective structures of the faces 6 and 8th correspond to each other. The polarimetrically effective structure 17 the subarea 7 has a changed angular orientation. The structures 16 . 17 . 18 are designed, for example, as roof-edge mirrors for generating a double reflection for emitted electromagnetic waves. The subarea 19 may be formed in a variant with a smooth surface, which causes no polarization change in the reflected electromagnetic wave. In another variant, the partial surface 9 a polarimetrically active material 19 on. All subareas and all polarimetrically active structures are formed without antennas.

The partial surfaces 6 . 7 . 8th . 9 Due to their different polarimetric properties, they can be identified by a polarimetric, imaging radar method. In this respect, the sequence of partial surfaces 6 . 7 . 8th or their corresponding structures or surfaces 16 . 17 . 18 . 19 clearly detected and thus the transponder 3 be clearly identified by its trained radar barcode.

In this way it becomes possible to determine the exact location of a specific motor vehicle in the monitored space or terrain. As a polarimetric measuring method, in particular the so-called iSAR method is suitable, wherein the movement of the object is used to form an inverse synthetic aperture.

In 3 becomes one too 1 complementary measuring method described. There is on a moving object 1 , which as a forklift 30 is formed, a mobile radar station 5 arranged, which has an omnidirectional receiving and transmitting capacity. The lift truck 30 moves, for example, in the direction of travel 33 , Parallel to the direction of travel extends a flat, two-dimensional transponder 31 , This points along the direction of travel 33 successively arranged partial surfaces 6 . 7 . 8th . 9 in the present case, for example, are formed as tiles and are arranged on a wall of a building or on a storage rack. The longitudinal axis 10 along which the partial surfaces 6 . 7 . 8th . 9 are arranged one behind the other, runs substantially parallel to the known direction of travel 33 ,

For identification of the transponder 31 it is preferred to use a SAR method, wherein the movement of the radar station 5 is used to form a synthetic aperture. Otherwise the identification of the transponder takes place 31 according to the above-described method with respect to the embodiment variant accordingly 1 and 2 ,

LIST OF REFERENCE NUMBERS

1

 object

2

 motor vehicle

3

 Transponder, 3D

4

 wall

5

 radar station

6-9

 subareas

10

longitudinal axis

16-18

polarimetric structures

19

polarimetrically active material

26-29

subsegments

30

lift trucks

31

Transponder, 2D

33

direction of travel

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• EP 1993168 A2 [0003]
• WO 2000039604 A1 [0005]
• WO 2011098719 A4 [0006]
• WO 2009126999 A1 [0006]
• WO 2013096995 A1 [0007]
• US 20050280504 A1 [0007]
• DE 19709847 A1 [0008]
• DE 202010018131 U1 [0008]
• WO 199013495 A1 [0008]
• WO 2015041295 A1 [0011]
• EP 2767849 A2 [0011]
• DE 102015117712 [0013, 0015]

Cited non-patent literature

• S. Preradovic, NC Karmakar, I. Balbin; "RFID Transponders", IEEE Microwave Magazine, October 2008, pages 90-103 [0002]
• M. Zomorrodi, NC Karmakar: "Image-based Chipless RFID System with High Content Capacity for Low Cost Tagging", IEEE International Microwave and RF Conference, pp. 41-44, 15-17 December 2014 [0007]
• MA Islam, NC Karmakar: "Design of a 16-bit Ultra Low Cost Fully Printable Slot-Loaded Dual-Polarized Chipless RFID Tag", Proceedings of the Asia-Pacific Microwave Conference, pages 1482-1485, 5-8 December 2011 [0007]
• A. Vena, E. Perret, S. Tedjni: "A Depolarizing Chipless RFID Tag for Robust Detection and Its FCC Compliant UWB Reading System", IEEE Transactions on Microwave Theory and Techniques, Vol. 61, 2013, No. 8, p. 2982 -2994 [0007]
• J. Adametz, L.-P. Schmidt: "Thread object classification with a close range polarimetric imaging system by means of H-alpha decomposition", European Radar Conference, pages 77-80, October 9-11 , 2013 [0011]
• T. Moriama, S. Uratsuka, Y. Yamaguchi: "A Study of Extraction of Urban Areas from Polarimetric Synthetic Aperture Radar Image," IEEE Geoscience and Remote Sensing Symposium, pp. 703-706, September 20-24, 2004 [0012]

Claims (16)

Method for locating a moving object ( 1 ), in which - a chipless, passive transponder ( 3 . 31 ), which passes through several subareas ( 6 . 7 . 8th . 9 ) encoded with different polarimetric property from a radar station ( 5 ) is irradiated with polarized electromagnetic waves, wherein the transponder ( 3 . 31 ) or the radar station ( 5 ) on the object ( 1 ), - from the radar station ( 5 ) on the transponder ( 3 . 31 ) reflected waves are generated, - generates a polarization-coded image from the reflected waves and the transponder ( 3 . 31 ) is detected on the basis of the polarization-coded image, - on the basis of the detected transponder ( 3 . 31 ) the object ( 1 ) and to a current position of the identified object ( 1 ) is closed. Method according to claim 1, wherein the transponder ( 3 . 31 ) from the polarization-coded image by analytically calculating the polarimetric property of at least one partial area ( 6 . 7 . 8th . 9 ) is recognized. Method according to claim 1 or 2, wherein the transponder ( 3 . 31 ) is detected on the basis of an image comparison of at least one partial image of the polarization-coded image with at least one reference image. Method according to one of the preceding claims, wherein the polarization-coded image is subjected to a Pauli decomposition and the transponder ( 3 . 31 ) based on at least one polarimetric property of a partial surface ( 6 . 7 . 8th . 9 ) is recognized from at least one pauli-decomposed image. Method according to one of the preceding claims, wherein a transponder ( 3 . 31 ) is used, the at least one partial area ( 6 . 7 . 8th . 9 ) having a polarimetrically active structure ( 16 . 17 . 18 ). Method according to one of the preceding claims, wherein a transponder ( 3 . 31 ), which comprises at least one partial area with a polarimetrically active material ( 19 ). Method according to one of the preceding claims, wherein the object ( 1 ) along a longitudinal axis ( 18 ) extending transponder ( 3 ) whose partial surfaces ( 6 . 7 . 8th . 9 ) each as the longitudinal axis ( 18 ) circumferential partial surfaces are formed. Method according to claim 7, wherein the transponder ( 3 ) along the longitudinal axis ( 18 ) of disc-shaped, each of the circumferential part lateral surfaces forming sub-segments ( 26 . 27 . 28 . 29 ) is composed. Method according to one of the preceding claims, wherein the object ( 1 ) the radar station ( 5 ), and wherein a planar transponder ( 31 ) whose partial surfaces ( 6 . 7 . 8th . 9 ) along a longitudinal axis ( 18 ) are arranged side by side. Method according to one of the preceding claims, wherein as object ( 1 ) a vehicle ( 2 ) is used. Passive chipless transponder ( 3 . 31 ) extending along a longitudinal axis ( 18 ) and by several partial surfaces ( 6 . 7 . 8th . 9 ) is encoded with different polarimetric property, wherein the partial surfaces ( 6 . 7 . 8th . 9 ) along the longitudinal axis ( 18 ) are arranged successively. Transponder ( 3 ) according to claim 11, whose partial surfaces ( 6 . 7 . 8th . 9 ) each as the longitudinal axis ( 18 ) circumferential partial surfaces are formed. Transponder ( 3 ) according to claim 12, which is along the longitudinal axis ( 18 ) of disc-shaped, each of the circumferential part lateral surfaces forming sub-segments ( 26 . 27 . 28 . 29 ) is composed. Transponder ( 31 ) according to claim 11, which is formed flat. Transponder ( 3 . 31 ) according to one of claims 11 to 12, which comprises at least one partial surface ( 6 . 7 . 8th . 9 ) having a polarimetrically active structure ( 16 . 17 . 18 ). Transponder ( 3 . 31 ) according to one of claims 11 to 15, which has at least one partial surface ( 6 . 7 . 8th . 9 ) with a polarimetrically active material ( 19 ).

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