Equipment and method for reading vehicle registration numbers of moving objects
Patent Information
- Application Number
- JP2024563294
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-04-26
- Filing Date
- 2023-01-18
- Publication Date
- 2025-10-29
AI Technical Summary
Existing UHF RFID readers struggle to reliably read multiple transponders on moving vehicles, especially in busy or multi-lane road conditions, due to limitations in position and direction dependency.
The proposed solution involves an equipment with a monopole antenna configuration, comprising a conductive plate element and two perpendicular rod elements, which allows for simultaneous reading of multiple transponders regardless of their position relative to the antenna. This equipment can be integrated into the road surface or installed above it, enabling detection of transponders from various angles and positions.
This solution enables high detection rates and wide detection ranges, allowing for reliable reading of multiple transponders on moving vehicles, even in complex traffic scenarios, and facilitates the calculation of moving profiles and speeds.
Smart Images
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Abstract
Description
[Technical field]
[0001] The present invention relates to an arrangement for reading UHF RFID signals according to the preamble of claim 1. Furthermore, the present invention relates to a method for reading UHF RFID signals according to the preamble of claim 19. [Background technology]
[0002] It is known that in order to identify a moving object, for example a motor vehicle, a contactlessly readable transponder is attached to the object. The transponder comprises a data memory in which any data relating to the object can be stored. In the case of a transponder arranged in a motor vehicle, the data can be, for example, information about the motor vehicle, information about the owner or information about insurance, etc. As is known, the transponder can be fixed to a sticker or a label on the motor vehicle or on the windscreen. In another embodiment, it is proposed that the contactlessly readable transponder is integrated into a registration plate. The registration plate can be, for example, a vehicle registration plate fixed to the motor vehicle.
[0003] Hand scanners can be used to read the transponders. Transponders on present objects are read by the hand scanner. For this, the hand scanner transmits a UHF (or NFC) RFID signal that is detected or reflected by the transponder. Information stored in a data memory can be read based on the signal transmitted or reflected from the transponder. In the case of moving objects, hand scanners have a very limited function or do not function at all. To read transponders arranged on moving objects or on moving vehicles, it is known that a reading device with an antenna is arranged close to the roadway. In this case, this reading device is present in a corresponding installation next to or above the roadway. Also known are embodiments in which the reading device or antenna is integrated into the roadway surface. It is known that a UHF antenna is used to read the RFID signal of the transponder.
[0004] As long as a moving object or vehicle approaches the antenna from a specific direction at a sufficiently long time interval, the transponder can be read at least almost reliably. However, if multiple transponders of a large number of vehicles have to be read on a busy, possibly multi-lane road and these vehicles come from several different directions, as may be the case, for example, at an intersection, the known reading device reaches its technical limits: it is not possible to perform a reliable reading of the multiple transponders of all vehicles. For this reason, such antennas cannot be used to detect vehicles, especially on toll roads. Summary of the Invention [Problem to be solved by the invention]
[0005] Therefore, the object of the present invention is to provide an apparatus and a method for reading transponders of moving objects, in which multiple objects can be detected simultaneously, i.e. independently of the position and direction of travel of the objects. [Means for solving the problem]
[0006] An installation for solving this problem has the features of claim 1. It is therefore proposed that the installation for reading UHF RFID signals transmitted or reflected from at least one transponder of a registration sign comprises at least one UHF RFID reader. The registration sign can be, for example, a vehicle registration plate, while the moving object can be a motor vehicle. This at least one reader for reading the transponder can be located next to, above or in the roadway along which the object is moving. The invention is characterized in that the at least one reader comprises an antenna configured as a monopole antenna. This antenna comprises an electrically conductive plate element and first and second electrically conductive rod elements, whereby the rod elements are arranged perpendicular to the plate element and are electrically insulated from it. It is proposed that the installation according to the invention is integrated into the roadway surface or is installed as at least one support pillar next to the roadway or is fixed to a traverse above the roadway. This is possible according to the invention. It is possible to read several moving transponders simultaneously or at short time intervals. In this case, a directional signal detected by the transponder and retransmitted or reflected is emitted from the antenna. The information detected by the antenna is then evaluated by the control device. In this case, it does not matter where the transponder or the object is located relative to the antenna; not only transponders moving towards the antenna in the direction of travel of the object can be detected, but also transponders moving away from the antenna in the direction of travel of the object. This makes it possible not only to detect transponders arranged in the front area of the vehicle, but also to detect transponders installed at the rear of the vehicle. Transponders of objects passing beside the reader, passing obliquely through the reader or crossing the reader can also be detected.
[0007] Due to the possibility of detecting transponders, i.e. moving objects, at several arbitrary positions relative to the antenna, the inventive arrangement also makes it possible to calculate the movement profile or speed of the object. Due to the particularly high detection rate and the large detection range, the used arrangement is very suitable for reading a large number of transponders moving around the antenna, as is the case, for example, on roads or intersections with a lot of traffic. It is conceivable that several of the inventive arrangements are arranged at a distance from each other and / or at different positions relative to the roadway, for example, in order to detect data redundantly or to detect several vehicles on several roads. By collating the data recorded for different times, information on the traffic flow and the evolution of the traffic volume can also be ascertained.
[0008] It is preferably proposed that a voltage source of a power supply network is attached to the plate and rod elements of the reader or antenna. A UHF RFID signal can be applied between the plate and rod elements by this voltage source. The signal of the reader can be radiated in different spatial directions by appropriately controlling the voltage. At least almost all transponders or objects in the surroundings of the reader can be detected by this changeable radiation characteristic of the antenna.
[0009] In particular, it is proposed that the first and second rod elements are spaced apart from each other by ¼ to ¾ wavelength of the UHF signal. This spacing of the rod elements results in less or more overlap of the electromagnetic waves emitted by both rod elements. This allows the generation of radiation characteristics adapted to the specific conditions of the antenna, depending on the amplitude and phase shift of the received signals of both rod elements.
[0010] Another preferred embodiment can be proposed in which the first and second rod elements are arranged at a distance from each other by half a wavelength, which also offers the possibility to generate a specific radiation characteristic of the measuring device by suitable control of the rod elements.
[0011] The invention further proposes that preferably the power supply network is configured such that a UHF RFID signal can be applied between the plate element and the second rod element by a voltage source, the phase of the UHF RFID signal being equal to the UHF RFID signal applied between the plate element and the first rod element. Similarly, it is conceivable that the power supply network is configured such that a UHF RFID signal can be applied between the plate element and the second rod element by a voltage source, the amplitude of the UHF RFID signal being equal to the UHF RFID signal applied between the plate element and the first rod element. If UHF RFID signals of the same phase and amplitude are supplied to both rod elements, a radiation characteristic with two main lobes is obtained. These main lobes are strongly deflected downwards (towards the plate element) with respect to the elliptical torus of the single monopole antenna. In this case, it has proven very beneficial that the diameter of the plate element can be less than 0.5 m to obtain the described effect. A higher radiated transmission power can be utilized due to the directed radiation characteristic thus to be achieved. This allows a wider detection range of the reader. As a result, the detection rate is higher and higher object velocities are detectable.
[0012] A very preferred embodiment is proposed in which the monopole antenna has a third and fourth rod element, each of which is arranged perpendicular to the plate element and is conductive, the third and fourth rod elements being spaced apart from each other by ¼ to ¾ wavelength of the UHF signal, the connection line between the first rod element 20 and the second rod element and the connection line between the third and fourth rod elements intersect at half the length (center) of these connection lines, and both connection lines are arranged perpendicular to each other. In this case, it is considered that the third rod element and the fourth rod element are spaced apart from each other by half the wavelength of the UHF signal.
[0013] It is further conceivable that the power supply network is configured such that the UHF RFID signal can be applied by a voltage source between the plate element and the third rod element and a voltage source between the plate element and the fourth rod element, which is phase shifted by 180° with respect to the UHF RFID signal applied between the plate element and the first rod element. Similarly, it is conceivable that the power supply network is configured such that the UHF RFID signal can be applied by a voltage source between the plate element and the third rod element and a voltage source between the plate element and the fourth rod element, which is in the same phase with respect to the UHF RFID signal applied between the plate element and the first rod element. A plurality of UHF RFID transponders pointing in a plurality of spatial directions can be detected by this arrangement of the rod elements. The detection direction with a high detection rate can be changed as required.
[0014] In particular, it is conceivable that the vertically arranged rod elements are configured as top-loaded monopoles. In this case, it is proposed that the rod elements have a circular, elliptical, square or rectangular conductive disk element at the end of the rod element that does not face the plate element. This allows the length of the rod elements to be reduced. In this case, the resonant frequency of the antenna is guaranteed. In this case, for example, a length of 3 cm for the rod elements is sufficient. The entire antenna arrangement can be made even flatter by this measure. As a result, the installation in the installation is simplified.
[0015] A further possible embodiment can be proposed in which the power supply network is configured such that three of the four rod elements can be shorted to the plate element and a UHF RFID signal can be applied between the plate element and the remaining rod elements by a voltage source, whereby the three shorted rod elements are used as reflectors for the electromagnetic beam emitted from the remaining rod elements. This has the advantage that the radiation characteristics can be directed in the direction of approaching vehicles, for example for use in dedicated lanes of highways or main roads, and thus a longer detection range, i.e. also a higher detection speed, is possible.
[0016] Furthermore, the invention can propose that the radiation characteristics of the at least one antenna can be changed, in particular periodically, by a voltage source. With this variant, the installation can be used situation-dependently and therefore very flexibly.
[0017] Another embodiment can be proposed in which the plate element has a conductive edge around its plate periphery facing the rod element, the height of the edge reaching at least the height of the end of the rod element not facing the plate element. It can further be proposed that the power supply network and / or the voltage source are integrated in a housing arranged on the side of the plate element not facing the rod element. It can further be conceived that the antenna is integrated on the side of the plate element facing the rod element such that said side is oriented in the direction of said surface. It is preferably proposed that two, three, four or more reading devices are arranged next to and / or above and / or on and / or in the road traveled by the moving object, in order to detect several objects simultaneously.
[0018] A method for solving the above problem has the means of claim 19. It is therefore proposed to read UHF RFID signals transmitted from or reflected from at least one transponder of a registration sign of a moving object, in particular a vehicle registration plate. In this case, the reading is carried out by means of an installation according to at least one of claims 1 to 18. The method according to the invention is characterized in that the radiation characteristic of at least one antenna is changed in such a way that the at least one antenna is pointed in the direction of the moving object. This allows each transponder of an object to be detected and read independently of its position relative to the installation. With the above method and the above installation, this can be carried out by means of a high sampling rate.
[0019] Preferably, the invention proposes that the voltage between the plate element and at least two rod elements of the antenna is changed in order to modify the radiation characteristics, which, according to this variation of the voltage, can be radiated in almost any direction.
[0020] It is preferably envisaged that UHF RFID signals from transponders (13) approaching the antenna and / or from transponders moving away from the antenna can be read by modifying the radiation characteristics of at least one such antenna, in such a way that the signals can be read within a 360° range around the antenna, in particular in a forward, backward, lateral or diagonal direction.
[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [Brief description of the drawings]
[0022] [Figure 1a] 1 shows a schematic representation of a possible embodiment of the method of the invention; [Figure 1b] FIG. 1b is another schematic diagram of the method according to FIG. 1a. [Diagram 2] 2 illustrates diagrammatically another embodiment of the method of the present invention; [Diagram 3] 2 illustrates diagrammatically another embodiment of the method of the present invention; [Figure 4] 2 illustrates diagrammatically another embodiment of the method of the present invention; [Figure 5a] 1 shows a schematic diagram of an installation according to the invention; [Figure 5b] The radiation characteristic of the installation according to FIG. 5a is shown. [Figure 6a] 2 shows another embodiment of the installation of the present invention. [Figure 6b] The radiation characteristic of the installation according to FIG. 6a is shown. [Figure 6c] 6b shows another radiation characteristic of the installation according to FIG. 6a. [Figure 7] 2 shows a schematic representation of another embodiment of the installation of the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The method of the invention makes it possible to read transponders of moving objects independently of the direction of movement of these objects. The moving object can be a motor vehicle. The transponder can be present, for example, on or in the license plate of the motor vehicle or in a label on the windshield. It is further conceivable that the transponder is present on the tire of the motor vehicle, on the inside of the motor vehicle or on another side of the motor vehicle. The data to be read and stored in the transponder can be linked to a toll system, a parking system or a fuel application or can be used to verify the identity of the motor vehicle or the owner of the motor vehicle. To read the data in a contact manner, the invention provides an installation with a reading device that is attached to the roadway along which the motor vehicle is moving. The figures show several possible embodiments. In particular, however, the invention is not limited to the embodiments shown here. It is instead proposed that the scope of protection also includes other embodiments.
[0024] 1a shows two motor vehicles moving in one driving direction 12 on a roadway 11. Each of the motor vehicles has a transponder 13 in the front and rear area. These transponders 13 can be integrated, for example, in the license plate of the motor vehicle 10. Alternatively, it is also conceivable that the transponders 13 are fixed elsewhere on the motor vehicle 10 or on other components of the motor vehicle 10, for example the wheels.
[0025] In the embodiment of the method according to the invention shown in Fig. 1a, a reader 14 is installed in the roadway 11 for transmitting and receiving UHF RFID signals. This reader 14 has at least one antenna, a control device 30 and an energy supply device or power supply network 31. The reader 14 is installed in the roadway 11 or in the surface of the roadway 11, so that the reader 14 is in the immediate vicinity of the motor vehicle 10 without disturbing the latter. As shown very diagrammatically in Fig. 1a, a transmission signal 15 is emitted by the reader 14. The transmission signal 15 can be focused or directed by the control device 30 such that the transmission signal 15 is directed towards the detected transponder 13. In this case, both the transponder 13 of the motor vehicle 10 approaching the reader 14 and the transponder 13 of the motor vehicle 10 moving away from the reader 14 in the direction of travel 12 can be detected. A transmitted signal 15 is reflected from the transponder 13, or the transponder 13, which may be an active or passive RFID chip, transmits a received signal 16. The reflected or received signal 16 is detected and evaluated by a reading device 14. Information stored in a data memory of the transponder 13 can be detected by means of the evaluated signal.
[0026] In addition to the embodiment shown in figures 1a and 1b, it is also conceivable that the reading device 14 is arranged on a pillar 17 next to the roadway 11 (figure 2). In this case the principle of operation of transmission and reception is the same as in the above-mentioned embodiment. The transmission or reception range of the reading device 14 can be increased by mounting the reading device 14 on the pillar 17.
[0027] Finally, it is also conceivable that the reader 14 is built into a traverse 18 installed above the roadway 11. This makes it possible to achieve both a wide transmission or reception range of the reader 14 and proximity of the reader 14 to the vehicle 10.
[0028] The method or the reading device 14 described here allows the detection of vehicles 10 not only on one roadway 11, but also on several roadways 11 arranged side by side. As shown diagrammatically in FIG. 4, the transmission signal 15 can be transmitted not only parallel to the roadway 11 in the direction of travel 12, but also perpendicular to the roadway 11. As a result, several vehicles 10 can be detected on other roadways 11. This is very useful in the case of roads with a lot of traffic and in the area of intersections. Similarly, the input signals of vehicles 10 located on different roadways 11, which are not shown in FIG. 4, can be detected. By successive detection of the signals, not only information about the vehicles 10 but also the speed of the vehicles 10 can be detected by the reading device 14.
[0029] In Fig. 5a a possible embodiment of a reader 14 or antenna device for UHF RFID signals is shown. This antenna device is characterized by two conductive rod elements 20, 21 arranged perpendicularly to a plate element 19. An important feature of this device is that both rod elements are spaced apart by half the wavelength of the UHF signal. In the configuration shown in Fig. 5a the plate element 19 lies in the xy plane and both rod elements 20, 21 are oriented parallel to the z axis.
[0030] A UHF RFID signal can be applied between the plate element 19 and the second rod element 21 by means of a voltage source, the power supply network 31 being configured to supply electrical energy to the reader 14 such that the phase and / or amplitude of said UHF RFID signal is equal to the UHF RFID signal applied between the plate element 19 and the first rod element 20. In the case of equal phase and amplitude, the radiation characteristic shown in FIG. 5b is obtained for the reader 14 shown in FIG. 5a. This radiation characteristic has two main lobes which are deflected towards the plate element 19. This characteristic arises due to the fact that the components of the electric fields of both electromagnetic beams radiated from the rod elements 20, 21 in the y direction overlap more and the components of the electric fields in the x direction overlap less.
[0031] In Fig. 6a, another embodiment of the reading device 14 according to the invention is shown. In parallel to the first rod element 20 and the second rod element 21, the antenna device has a third rod element 22 and a fourth rod element 23, which are also oriented perpendicular to the plate element 19 and parallel to the rod elements 20, 21. Both rod elements 22, 23 are also made electrically conductive. The third rod element 22 and the fourth rod element 23 are arranged at a distance from each other by half the wavelength of the UHF signal. The connection lines between the first rod element 20 and the second rod element 21 and between the third rod element 22 and the fourth rod element 23 cross each other on half the length of the connection lines (in the center). Both connection lines are arranged perpendicular to each other. The four rod elements 20-23 thus form the vertices of a square. In this case, the diagonals connecting the opposite vertices have a length of half the wavelength of the UHF signal.
[0032] In this embodiment, the feeding network 31 is configured such that a UHF RFID signal can be applied by a voltage source between the plate element 19 and the third rod element 22 and between the plate element 19 and the fourth rod element 23, which is phase shifted by 180° and / or of the same amplitude with respect to the UHF RFID signal applied between the plate element 19 and the first rod element 20. In the case of a phase shift of 180° and respectively the same amplitude, the radiation characteristic shown in FIG. 6b is obtained for the antenna arrangement shown in FIG. 6a. This radiation characteristic has four main lobes. In this case, the feeding network 31 can be further configured such that three of the four rod elements 20-23 can be shorted to the plate element 19 and a UHF RFID signal can be applied between the plate element 19 and the remaining rod elements by a voltage source. The resulting radiation characteristic of the reader 14 is shown in FIG. 6c.
[0033] In Fig. 7, another embodiment of the reading device 14 of the invention is shown. Here, vertically arranged rod elements 20-23 are configured as top-loaded monopoles. For this purpose, in the illustrated configuration, the rod elements 20-23 have a conductive disk element 24-27 at the end of the rod element that does not face the plate element 19. The illustrated disk element 24-27 is circular in shape. However, it is also conceivable that the disk element is oval, square or rectangular, etc.
[0034] Furthermore, the plate element 19 has a conductive edge 28 on the plate periphery, facing the rod elements 20-23. The height of the edge 28 reaches at least the height of the end of the rod elements 20-23 that does not face the plate element 19. However, the edge 28 may also protrude beyond the end of the rod elements 20-23 that does not face the plate element 19. The power supply network 31 and the voltage source are integrated in a housing that is arranged on the side of the plate element 19 that does not face the rod elements 20-23. Optionally, the antenna arrangement can be covered by a conductive cover 29 so that the rod elements 20-23 are protected from mechanical and chemical influences.
[0035] The antenna arrangement shown here is mounted in the roadway 11 such that the face of the plate element 19 facing the rod elements 20-23 is oriented towards the roadway surface.
[0036] Furthermore, the present invention is not limited to the first rod element 20 and the second rod element 21 being spaced apart from each other by half the wavelength of the UHF signal. In another configuration, the first rod element 20 and the second rod element 21, and / or the third rod element 22 and the fourth rod element 23 are spaced apart from each other by ¼ to ¾ of the wavelength of the UHF signal. [Explanation of symbols]
[0037] 10. Automobiles 11 Roadway 12 Travel direction 13 Transponder 14 Reading device 15 Transmitting Signal 16 Received Signal 17 Posts 18 Traverse 19 Plate Elements 20 Rod elements 21 Rod elements 22 Rod elements 23 Rod elements 24 Plate elements 25 Plate elements 26 Plate elements 27 Plate elements 28 Edge 29 Cover 30 Control device 31 Power grid 32 Main Lobe 33 Main Lobe 34 Main Lobe 35 Main Lobe 36 Main Lobe 37 Main Lobe
Claims
1. 1. An installation for reading, by means of at least one UHF RFID reader (14), UHF RFID signals transmitted from or reflected from at least one transponder (13) in a registration sign, in particular a vehicle registration plate, of a moving object, preferably a motor vehicle (10), comprising: The reader (14) has at least one antenna; In this installation, at least one reading device (14) is installed at least one of beside, above and on the road, preferably the carriageway (11) traveled by the moving object, and / or installed in the road surface, in particular the carriageway surface, the antenna of at least one of the reading devices (14) is configured as a monopole antenna having a conductive plate element (19) and a first conductive rod element and a second conductive rod element (20, 21); The rod elements (20, 21) are arranged perpendicular to the plate element (19), and the plate element (19) and the rod elements (20, 21) are electrically insulated from each other.
2. 2. The installation for reading UHF RFID signals according to claim 1, characterized in that a power supply of a power supply network (31) of the UHF RFID reading device (14) is assigned to the plate element (19) and the rod elements (20, 21) in order to apply a UHF RFID signal between the plate element (19) and the rod elements (20, 21).
3. 3. The device for reading UHF RFID signals according to claim 1 or 2, characterized in that the first rod element (20) and the second rod element (21) are spaced apart from each other by ¼ to ¾ wavelength (λ / 4 to ¾λ) of the UHF signal.
4. 2. The apparatus for reading UHF RFID signals according to claim 1, wherein the first rod element (20) and the second rod element (21) are spaced apart from each other by half a wavelength (λ / 2) of the UHF signal.
5. 2. The arrangement for reading UHF RFID signals according to claim 1, characterized in that the power supply network (31) is configured such that a UHF RFID signal can be applied between the plate element (19) and the second rod element (21) by a voltage source, the UHF RFID signal being equal in phase to the UHF RFID signal applied between the plate element (19) and the first rod element (20).
6. 2. The arrangement for reading UHF RFID signals according to claim 1, characterized in that the power supply network (31) is configured such that a UHF RFID signal can be applied between the plate element (19) and the second rod element (21) by a voltage source, the amplitude of the UHF RFID signal being equal to the UHF RFID signal applied between the plate element (19) and the first rod element (20).
7. The monopole antenna has third and fourth rod elements (22, 23) that are electrically conductive and disposed perpendicular to the plate element (19), The third rod element (22) and the fourth rod element (23) are arranged at a distance of 1 / 4 to 3 / 4 wavelength (λ / 4 to 3 / 4λ) from each other of the UHF signal, a connecting line between the first rod element (20) and the fourth rod element (23) and a connecting line between the second rod element (21) and the third rod element (22) intersect on half sections of these connecting lines, 2. The device for reading UHF RFID signals according to claim 1, characterized in that both connecting lines are arranged perpendicular to each other.
8. 8. The apparatus for reading UHF RFID signals according to claim 7, characterized in that the third rod element (22) and the fourth rod element (23) are spaced apart from each other by half the wavelength (λ / 2) of the UHF signal.
9. 9. The arrangement for reading UHF RFID signals according to claim 7 or 8, characterized in that the power supply network (31) is configured such that a UHF RFID signal, which is phase-shifted by 180° with respect to a UHF RFID signal applied between the plate element (19) and the first rod element (20), can be applied by a voltage source between the plate element (19) and the third rod element (22) and between the plate element (19) and the fourth rod element (23) of the UHF RFID reading device (14).
10. 9. The arrangement for reading UHF RFID signals according to claim 7 or 8, characterized in that the power supply network (31) of the UHF RFID reader (14) is configured such that UHF RFID signals can be applied between the plate element (19) and the third rod element (22) and between the plate element (19) and the fourth rod element (23) by a voltage source, the UHF RFID signals being in phase with the UHF RFID signal applied between the plate element (19) and the first rod element (20).
11. 9. The installation according to claim 7 or 8, characterized in that the vertically arranged rod elements (20-23) are configured as top-loaded monopoles.
12. 9. The arrangement for reading UHF RFID signals according to claim 7 or 8, characterized in that the rod elements (20-23) have conductive disc elements (24-27) of circular, oval, square or rectangular shape at the end of the rod elements facing away from the plate element (19).
13. Equipment for reading UHF RFID signals as described in claim 7 or 8, characterized in that the power supply network (31) of the UHF RFID reading device (14) is configured so that three of the four rod elements (20-23) can be short-circuited to the plate element (19) and the UHF RFID signal can be applied between the plate element (19) and the remaining rod elements by a voltage source.
14. 2. Arrangement for reading UHF RFID signals according to claim 1, characterized in that the radiation characteristics and / or radiation direction of the at least one antenna can be changed, in particular periodically, by a voltage source.
15. The plate element (19) has a conductive edge (28) on its periphery facing towards the rod elements (20-23), 9. The device for reading UHF RFID signals according to claim 7 or 8, characterized in that the height of the edge (28) reaches at least the height of the end of the rod elements (20-23) that does not face the plate element (19).
16. Equipment for reading UHF RFID signals as described in claim 7 or 8, characterized in that the power supply network (31) and / or voltage source of the UHF RFID reading device (14) is incorporated into a housing arranged on the side of the plate element (19) that does not face the rod elements (20-23).
17. 9. The installation for reading UHF RFID signals according to claim 7 or 8, characterized in that the antenna is integrated into the surface of the roadway (11) so that the side of the plate element (19) facing the rod elements (20-23) is directed towards said surface.
18. 2. An installation for reading UHF RFID signals according to claim 1, wherein two, three, four or more reading devices (14) are placed next to and / or above and / or on and / or in the road travelled by the moving objects in order to detect multiple objects simultaneously.
19. 10. A method for reading UHF RFID signals transmitted from or reflected from at least one transponder (13) of a registration sign, in particular a vehicle registration plate, of a moving object, preferably a motor vehicle (10), by means of an installation according to claim 1, comprising:
10. A method for reading UHF RFID signals, wherein the radiation characteristics of at least one antenna are modified such that the at least one antenna is pointed in the direction of the moving object.
20. 20. The method for reading UHF RFID signals according to claim 19, characterized in that the voltage between a plate element (19) and at least two rod elements (20, 21) of the antenna is changed to change the radiation characteristics.
21. 21. The method according to claim 19 or 20, characterized in that by changing the radiation characteristics of at least one of the antennas, UHF RFID signals from the transponders (13) approaching the antenna and / or UHF RFID signals from transponders (13) moving away from the antenna are read.
22. 20. The method of claim 19, wherein the radiation characteristics of at least one of the antennas are modified so that they are read within a 360° range around the antenna, in particular in a forward, backward, sideways or diagonal direction.