ROLLABLE ANTENNA MAT

Abstract

A rollable antenna mat for sports timing comprises one or more planar antenna structures connected to one or more transmission lines for conveying signals to and/or from the one or more planar antenna structures. Each of the one or more planar antenna structures comprises a conductive plate positioned above a conductive ground plane. A spacer element is positioned between the conductive ground plane and the conductive plate. The planar antenna structure is configured to generate a radiation field having a main axis that is substantially perpendicular to the conductive plate. The planar antenna structure and a transmission line is embedded in a flexible elongated sheet structure of one or more elastomeric materials, and comprises the embedded one or more planar antenna structures being suitable to be rolled up in a roll, the axis of the roll being substantially perpendicular to the longitudinal axis of the flexible elongated sheet structure.

Claims

1. A rollable antenna mat for sports timing comprising: one or more planar antenna structures connected to one or more transmission lines configured to convey signals to and/or from the one or more planar antenna structures; each of the one or more planar antenna structures comprising at least one conductive plate positioned above a conductive ground plane, a spacer element positioned between the conductive ground plane and the conductive plate, the planar antenna structure being configured to generate a radiation Held, the radiation Held having a main axis that is substantially perpendicular to the conductive plate; and, the planar antenna structure and at least one transmission line being embedded in a flexible elongated sheet structure of one or more elastomeric materials, the flexible elongated sheet structure comprising the embedded one or more planar antenna structures being suitable to be rolled up in a roll, the axis of the roll being substantially perpendicular to the longitudinal axis of the flexible elongated sheet structure.

2. The rollable antenna mat according to claim meter; and/or wherein a length of the flexible sheet structure is selected between 1 and 15 meter; and/or, wherein a width of the flexible sheet structure is selected between 30 and 120 cm; and/or, wherein a maximal thickness of the flexible sheet structure is selected between 2 and 6 cm; and/or, wherein length and width dimensions of the antenna structure is selected between 5 cm and 50 cm; and/or, wherein the diameter of the roll is selected between 100 and 25 cm.

3. The rollable antenna mat according to claim 1 wherein the spacer element comprises a honeycomb structure and/or, wherein the spacer element comprises a plastic material.

4. The rollable antenna mat according to claim 1 wherein the flexible sheet structure comprises one or more laminated and/or bonded sheets of one or more flexible elastomeric materials, the flexible sheet structure including at least a first sheet and a second sheet, wherein the one or more planar antenna structures and the one or more transmission lines are positioned between the first and second sheet.

5. The reliable antenna mat according to claim 4 wherein first sheet includes a first rubber material and/or, wherein the second sheet includes a second rubber material.

6. The rollable antenna mat according claim 4, wherein at least one of the first and second flexible sheet comprises a region having a honeycomb structure that is formed by a plurality of repealing units that each have a length and/or width between 5 and 10 mm, the repeating units including at least on of: hexagonal cells, triangular cells, square cells and/or combinations thereof.

7. The rollable antenna mat according to claim 4, wherein at least one of the first and second flexible sheet comprises one or more recessed spaces in the flexible material, the one or more recessed spaces being shaped for housing the one or more planar antenna structures and the one or more one or more transmission lines.

8. The rollable antenna mat according to claim 1, wherein each of the one or more transmission lines includes a signal line connected to the conductive plate and a ground line connected to the conductive ground plane.

9. The rollable antenna mat according to claim 8 wherein the signal line is connected to the conductive plate via a microstrip formed in the conducting plate.

10. The rollable antenna mat according to claim 1, wherein each of the one or more coaxial transmission lines comprises: an inner conductor forming a signal line, an outer conductor around the inner conductor forming a ground line and a dielectric between the inner and outer conductor; the inner conductor being connected to the conductive plate and the outer conductor being connected to the conductive ground plane.

11. The rollable antenna mat according to claim 10 wherein an end part of the coaxial transmission line is oriented parallel to an edge of the antenna structure, the edge of the antenna structure being parallel to the roll axis of the roll.

12. The rollable antenna mat according to claim 10 wherein at the connection point between the inner conductor and the conductive plate, the inner conductor is oriented parallel to the roll axis of the antenna mat.

13. The rollable antenna mat according to claim 1 comprising one or more test device, the test device being configured to receive a test signal from at least one of the one or more planar antenna structures and/or to transmit a test signal to at least one of the one or more planar antenna structures.

14. The rollable antenna mat according to claim 1, wherein a flexible conductive sheet is provided below the one or more planar antenna structures for reducing signal dissipation into the ground when the antenna mat is positioned across the race track.

15. The rollable antenna mat assembly according to claim 1 and further comprising: a cylindrically shaped roll element, the roll element having a curved surface the antenna mat can be wound around the roll element.

16. The rollable antenna mat assembly according to claim 15 wherein the rollable antenna mat is mechanically and electrically connectable to the roll element; and/or, the roll element comprising an antenna controller connected to the one or more transmission lines of the rollable antenna mat.

17. The rollable antenna mat assembly according to claim 1 and further comprising: a carrier structure for transporting and lifting the antenna mat roll.

18. The rollable antenna mat according to claim 17, wherein the carrier structure includes wheels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0071] FIG. 1 illustrates an antenna mat according to an embodiment; and

[0072] FIG. 2A-2E illustrate an antenna mat according to various embodiment of the invention;

[0073] FIG. 3 illustrates a bend radius of a sheet of material;

[0074] FIG. 4A-4B depict structured elastomeric sheets for an antenna mat according to an embodiment of the invention;

[0075] FIG. 5 depicts a top view of part of an antenna mat according to an embodiment of the invention;

[0076] FIG. 6 depicts a three-dimensional view of part of an antenna mat according to an embodiment of the invention;

[0077] FIGS. 7A-7C depict a three-dimensional view of a planar antenna structure according to an embodiment of the invention;

[0078] FIG. 8 shows a top view of a planar antenna structure according to an embodiment of the invention;

[0079] FIG. 9 depicts a three-dimensional view of a planar antenna structure according to an embodiment of the invention;

[0080] FIG. 10A-10B depict a rollable antenna mat for sports timing according to an embodiment of the invention;

[0081] FIG. 11 depicts connection means for connecting two antenna mat modules into a rollable antenna mat according to an embodiment of the invention;

[0082] FIG. 12A-C illustrate antenna mat assemblies according to various embodiments of the invention.

[0083] FIG. 13A-13D illustrate antenna mat assemblies according to various embodiments of the invention;

[0084] FIG. 14A-14B depict stackable antenna mat assemblies according to various embodiments of the invention;

[0085] FIG. 15 depicts antenna mat assemblies according to another embodiment of the invention.

[0086] FIG. 16A-16C depict stackable antenna mat rolls according to an embodiment of the invention.

DETAILED DESCRIPTION

[0087] FIG. 1 illustrates a rollable antenna mat assembly 1 according to an embodiment of the invention. The antenna mat assembly may include an antenna mat structure 2 (or in short the antenna mat) and a cylindrical roll 10. The antenna mat may include an elongated flexible sheet structure which can be rolled-up and unrolled across a race track 4. Examples of a race track may include a running course, e.g. for a marathon or an obstacle race, a speed skating ice ring, a circuit for car racing, a circuit for motor racing, etc. In this example, the antenna mat 2, when unrolled across the track 4 may have a length L and a width W. The length of the antenna mat may be selected such that it extends across substantially the entire width of the race track 4. The length L of the antenna mat, when unrolled may be between 1 and 15 meter, preferably between 2 and 8 meter. In an embodiment, the length L may be approximately 6 meters. Similarly, the width W may be between 20 and 70 cm.

[0088] In an embodiment, flexible sheet structure may comprise one or more (laminated and/or bonded) sheets of a flexible material that has a large abrasion resistance, tear strength, chemical resistance, temperature compatibility and aging. In an embodiment, flexible material may include a rubber material, for example a (synthetic) rubber elastomeric material based on styrene and/or butadiene, e.g. a styrene-butadiene rubber (SBR) material. Alternatively, one or more other elastomeric materials may be used including but not limited to butyl rubber and/or nitrile rubber (NBR). Alternatively and/or in addition, the flexible sheet structure may comprise one or more sheets of an elastomeric polyurethane material. Preferably, at least part of the sheets may be fabricated and structured using a moulding technique.

[0089] In an embodiment, the (rigid) cylindrical roll 10 or tube may be used to roll the antenna mat into a rolled-up state. As shown in the figure, the roll axis 5 of the roll (the x-direction in FIG. 1) may be substantially perpendicular to the longitudinal axis 3 of the sheet (the x-direction in FIG. 1). The antenna mat wound around the roll may form an antenna mat roll. The thickness of flexible sheet structure and the used elastomeric materials may be selected such that the antenna mat can be wound around a roll 10 having a diameter selected between 100 and 25 cm, preferably between 80 and 28 cm, more preferably between 60 and 30 cm.

[0090] The antenna mat 2 may comprise one or more planar ultra-high frequency UHF antenna structures. In an embodiment, the one or more UHF antenna structures may be implemented as patch and/or slotted antenna structures. A planar UHF antenna structure may comprise at least one conductive plate, e.g. a patch, positioned above a conductive ground plane, wherein a (dielectric) spacer element is positioned between the conductive ground plane and the conductive plate. The planar UFH antenna structure may be configured to generate a radiation field, wherein the radiation field has a main axis that is substantially perpendicular to the conductive plate.

[0091] Each of the planar antenna structures may be connected to a coaxial transmission line 7a,7b, such as a low-loss UHF coax cable, for providing an UHF connection between a planar antenna structure and an antenna controller. At least part of the transmission lines may be embedded in the elongated flexible sheet structure of the antenna mat. In an embodiment, one end of the antenna mat may be mechanically connectable to the roll. In one example, the antenna mat is affixed to the roll by means of one or more screws. In that case, in an embodiment, the antenna structures embedded in the antenna mat may also be electrically connectable to UHF transmission lines in the roll. In an embodiment, at least one side (a base) of the (hollow) roll may include a wall comprising UHF connectors 15a,15b wherein each of the UHF connectors is connected via at least one transmission line to one of the antenna structures.

[0092] In an embodiment, the antenna mat may be part of an RFID system, wherein an antenna controller controls the antennas to generate a radiation field at a certain frequency, wherein the (main) axis of the radiation field points in an upward direction away from the antenna mat (e.g. in the positive z-direction perpendicular to the plane of the mat). If a transponder, e.g. an active or passive UHF tag, moves into the radiation field, the transponder 8 may be triggered to transmit one or more signals back to the antenna mat, which may be detected by one of the patch antennas. The transponder 8 may be worn by an athlete, for example on a shoe or bib worn by a participant of the sports event. Alternatively, the transponder 8 may be attached to a vehicle of a participant of a sports event, such as a race car, motorcycle or a flying drone. The transponder signal may include a unique identifier associated with the transponder which can be linked with a participant.

[0093] In an embodiment, the RFID system may be a sport timing system for determining a passing time of the transponder 8. In for example, the antenna mat may be used as a detection antenna of a sports timing system as e.g. described in WO2015/140271A1, which is hereby incorporated by reference into this application. Typically, the transponder is configured to transmit one or more signals comprising an identifier ID to the antenna mat, which will detect and analyse the transponder signals so that the passing time of the transponder can be detected.

[0094] As shown in the figure, the rollable antenna mat allows very fast and efficient installation and setup of a timing line. An organizer of a race event merely needs to position an antenna mat roll at one side of the race track 4 and to unroll the mat in order to position the antenna. In the unrolled state, the antennas and the wiring are embedded in and protected by the elongated flexible sheet structure and thus optimally positioned in the mat. In case the roll includes the electrical connectors, the UHF connectors, the mat can be directly connected to an antenna controller.

[0095] Different arrangements of planar antenna structures may be possible. FIG. 2A-2E illustrate top views of antenna mat structures according to various embodiment of the invention. FIG. 2A schematically shows an embodiment of an antenna mat 2 comprising a single planar UHF antenna structure 6. The antenna structure may be connected to an UHF transmission line 12, e.g. an UHF coaxial transmission line, which may be at least partially embedded in the flexible sheet structure. The coaxial transmission line 12 may be configured to convey signals between the patch antenna 6 and an antenna controller 18. The antenna controller 18 may be configured to control the planar antenna structures embedded in the antenna mat. Such controllers are well known in the art and typically include receiver circuitry for enabling at least part of the antenna structures in the antenna mat to receive a signal from a transponder and transmission circuitry for enabling at least part of the antenna structures in the antenna mat to transmit a modulated carrier signal. The controller may further include a processor configured to process received signals and/or to prepare signals to be transmitted by the patch antenna. Processing such signals typically involves at least one of (de)modulating signals, applying filters to signals, such as low-pass and high-pass filters.

[0096] As shown in FIG. 2A, a coaxial transmission line 12 embedded in a flexible elongated sheet structure may electrically connect at least one planar antenna structure to at least one UHF connector structure 14 located one of the short edges of the elongated sheet structure. UHF connector structure 14 may be used to connect the embedded planar antenna structures via a further coax line 16 to external electronics such as the antenna controller. In an embodiment, the UHF connector structure may be integrated in the side of the short edge of the a flexible elongated sheet structure.

[0097] FIG. 2B schematically shows an embodiment of an antenna mat comprising a plurality of planar UHF antenna structures 6a-6f. In an embodiment, the planar UHF antenna structures may be arranged in pairs, e.g. first pair antennas 6a and 6b, second pair antennas 6b and 6c, third pair antennas 6e and 6f, etc. Each pair may comprise two planar UHF antenna structures 6a-6f that are positioned relatively close to each other. Preferably, a distance d2 between pairs of UHF antenna structures is larger than the distance d1 between two antennas forming such pair.

[0098] In one embodiment, the controller 18 may be configured to control the plurality of antennas. In a first time period the controller may control a first subset of one or more antennas out of the plurality of antennas to transmit signals for triggering UHF tags passing the antenna mat to transmit tag signals back to the antenna mat. Then, in a subsequent second time period the controller may control a second subset of one or more antennas out of the plurality of antennas to transmit signals for triggering UHF tags passing the antenna mat, wherein first subset and second subset include different antennas. In an embodiment, when a first subset of antennas is in a transmitting mode, the second subset of antennas may be in a signal receiving mode in which the antennas are configured to receive UHF tag signal. Likewise, when the second subset is in the transmitting mode, the first set is in the signal receiving mode.

[0099] In one embodiment, a first antenna and second antenna of an antenna pair may belong to different antenna subsets, e.g. one in the first subset so that this one antenna transmits during the first time period and the two neighbouring antennas on either side in the second subset so that these neighbouring antennas transmit during the second time period.

[0100] In yet another embodiment, the plurality of antennas may comprise more than two subsets, such as three subsets of antennas. In this case, the first subset may transmit during a first time period, the second during a second time period, the third during a third time period, et cetera. These time periods preferably follow directly after each other. In one example, the plurality of antennas consists of as many subsets as antenna, each subset comprising one and only one antenna. Then, during a first time period, a first antenna may be in transmitting mode, during the second time period a second antenna may be in transmitting mode, during the third time period a third antenna may be in transmitting mode, et cetera. These time periods may follow directly after each other.

[0101] In one embodiment, a pair of patch antennas belongs to the same subset. In this embodiment, preferably, pairs of antennas belong to a different subset, so that two neighbouring pairs do not transmit simultaneously. In case the plurality of antennas comprises more than two subsets, the plurality of antennas may comprise as many subsets as there are antenna pairs in the antenna mat, wherein each subset comprises one and only one antenna pair. Then, a first pair may be in transmitting mode during a first time period, a second pair during a second time period, a third pair during a third time period, et cetera. Again these time periods may follow directly after each other.

[0102] The above described transmission schemes advantageously reduce cross-talk between the antennas, which can distort measurements. Cross-talk may be understood to occur when an antenna sitting in a signal receiving mode receives a signal directly, e.g. without the signal being backscattered from a device that is passing the timing mat, from another antenna that is transmitting a signal. The above-described time periods in which an antenna transmits a signal typically last 3 ms.

[0103] FIG. 2C schematically an embodiment of an antenna mat, wherein a splitter device 20 for splitting UHF signals is positioned near each antenna pair. Such splitter may be used to reduce the amount of coaxial transmission lines that needs to be embedded in the antenna mat.

[0104] FIG. 2D schematically shows an embodiment of an antenna mat comprising at least one test device 22 having a fixed position relative to at least one to be tested patch antenna. The test device 22 may be configured to receive a test signal from an antenna and/or to transmit a test signal to an antenna that needs to be tested. The test signals may be used to assess the performance a planar UHF antenna structure that is embedded in rollable antenna mat structures as described with references to the embodiments described in this application. In an embodiment, the test device may be a transponder, e.g. an active or passive transponder.

[0105] A test protocol may be executed by the antenna controller, wherein the test protocol may include controlling a planer UHF antenna structure to transmit an antenna test signal of a predetermined amplitude and phase. In response, the antenna test signal may trigger the test device, e.g. a (passive or active) transponder, to measure one or more signal strengths of the test signal transmitted by the antenna structure and to transmit a transponder test signal back to the antenna structure, wherein the transponder test signal may include the one or more measured signal strengths. The test may include comparing the transponder test signal, in particular the one or more signal strengths, with a reference signal. Based on the comparison, the controller may determine whether the antenna structure functions according to the specifications or not. The test protocol may be performed for each antenna structure in the antenna mat.

[0106] FIG. 2E schematically shows an embodiment of an antenna mat which may comprise, in addition to one or more planar antenna structures 6, at least one loop antenna 24. The loop antenna may form a coil for generating a magnetic field. The loop antenna may be used to generate a magnetic field which may inductively couple with a magnetic coil of a transponder moving over the antenna mat. Such inductively coupled transponders may be used to determine very accurate passing times. Such sports timing system are e.g. described in WO2016/097215, which is hereby incorporated by reference. For clarity reasons, the transmission lines for connecting the planar antenna structures 6 is not shown.

[0107] The antenna mat structures described with reference to FIGS. 1 and 2 are configured to be wound around a roll of a predetermined diameter. Typically, the roll may have a diameter selected between 100 and 25 cm, preferably between 80 and 28 cm, more preferably between 60 and 30 cm. FIG. 3 illustrates a bend radius R of a flexible sheet of material 20 having a thickness D. The bend radius R is the radius of curvature that the inner surface of the sheet makes. The minimum bend radius is the smallest radius R for which the sheet of material 20 does not damage and/or does not permanently deform. The smaller the minimum bend radius of a material, the higher its flexibility and the lower its bending rigidity.

[0108] The materials and the dimensions (especially the thickness) of the elongated flexible sheet structure of the antenna mat may be selected to have a relative low bending rigidity, whereas the materials and dimensions (especially the thickness) of the planar antenna structures may be selected to form a structure of a bending rigidity that is higher than the bending rigidity of the flexible sheet structure. Thus, the bending rigidity of the flexible sheet structure and the planar antenna structure may be expressed in terms of the flexural or bend modus of the materials that are used for the flexible sheet structure and the antenna structure respectively. The flexural or bend modus may be determined based on a standardized measurement protocol, e.g. ASTM D790 and ISO 178 test methods.

[0109] FIGS. 4A and 4B depict an elongated flexible sheet structure of an antenna mat according to an embodiment of the invention. FIG. 4A shows a first top surface of an elongated flexible sheet element 25 that may function as flexible cover sheet. The elongated flexible sheet element may include one or more sheets of one or more flexible materials e.g. one or more rubber materials, for example a (synthetic) rubber elastomeric material based on styrene and/or butadiene, e.g. a styrene-butadiene rubber (SBR) material, a butyl rubber and/or nitrile rubber (NBR) material or an elastomeric polyurethane material. As shown in FIG. 4A the top surface may include anti-slip grooves 26, so that participants are less likely to slip and fall when stepping onto the antenna mat. Furthermore, the thickness of the peripheral parts 27a,27b parallel to the longitudinal sides of the sheet may be relatively thin when compared with the thickness of the central part 27c of the flexible sheet element. The thickness of the peripheral parts 27a, 27b may be in the range 2-5 mm, preferably approximately 3 mm. The thickness of the central part may be in the range 8-13 mm, preferably 11 mm.

[0110] FIG. 4B depicts a back view of the flexible sheet element. This figure shows that the back surface of the elongated flexible sheet element 25 is structured so that the planar antenna structures and the coaxial transmission lines can be embedded in the sheet element. In one embodiment, sheet element may comprise one or more recessed spaces 30a,30b, e.g. cavities, which are shaped in the form of the planar antenna structures. Furthermore, in an embodiment, flexible sheet element may comprise one or more elongated recessed spaces, e.g. channels and/or grooves, for embedding coaxial transmission lines. In an embodiment, the elongated recessed spaces for the coaxial transmission lines may be located in the peripheral parts 27a,27b of the longitudinal sides of the flexible sheet element. The recessed spaces may accurately follow the shape of the planar antenna structures and the transmission lines so that the planar antenna structures are accurately positioned within the antenna mat. Accurate positioning of UHF elements like the antenna structures and the coaxial transmission line it is important as mechanical loads on the UHF elements may locally changes the UHF impedance of elements, which may cause degradation of the performance of the mat antenna.

[0111] To illustrate, in the embodiment of FIG. 4B a coaxial transmission line that is to be connected to e.g. a patch antenna in cavity 30a may be positioned in channel 32a and coaxial transmission line that is to be connected to the patch antenna in cavity 30b can be positioned in channel 32b. Channels 32a and 32b merge into side channel 34a in which two transmission line can be positioned. A side channel may be understood to be a channel extending along the length of the antenna mat that is preferably positioned near a longitudinal side of the antenna mat. Furthermore, the antenna mat comprises side channels 34b,34c,34d, 34e, 34f. Each side channel can receive at least one coaxial transmission line, preferably at least two coaxial transmission lines, for electrically connecting patch antennas to a controller that is external to the antenna mat. In this example, the two cables respectively connected to the two antennas of an antenna pair are positioned together in the same side channel. The side channels 34 may guide the coaxial transmission lines to the side of the antenna mat, e.g. to one or more openings in the antenna mat at which one or more coaxial transmission lines can enter/exit the antenna mat.

[0112] The antenna mat, in particular the flexible material, may comprise at least one region 36 comprising honeycomb structures. Such an area is advantageous because it reduces the weight of the antenna mat without significantly weakening the mechanical strength of the antenna mat 2. In an embodiment, the honeycomb structure may include cells. The shape of the cells may include at least one of: (circular-cored) hexagonal cell, (circular-cored) triangular cells, (circular-cored) triangular cells, (circular-cored) square cells and/or combinations thereof.

[0113] The flexible sheet element may further comprise one or more protrusions 38a at a first short side of the sheet element and one or more recessed spaces at the second short side (opposite the first short side) wherein the one or more recessed spaces are shaped to receive protrusions of a further sheet element. Hence, the flexible sheet element may be used to form an long flexible sheet by mechanically connecting elements using the protrusions and corresponding recessed spaces at the short sides of the sheet elements. This way, during manufacture of an antenna mat, multiple sheet elements may be used to form a long flexible top sheet of an antenna mat. After positioning the one or more protrusions 38 of one antenna mat into the one or more cavities 40 of another antenna mat. Such modular approach allows easy and flexible manufacturing of rollable antenna mats of different lengths.

[0114] In a further embodiment, flexible sheet element may further comprise a channel 35 for receiving a coaxial transmission line, wherein the channel may guide a coaxial transmission line from a first longitudinal side of the antenna mat to the second longitudinal side of the antenna mat. Such channel 35 allows rerouting of coaxial transmission lines from a side channel on one long side of the antenna mat to a side channel 34d on the other long side of the antenna mat 2. These one or more coaxial transmission lines are then connected to patch antennas that are positioned in another antenna mat (not shown). In an embodiment, flexible sheet elements as depicted in FIGS. 4A and 4B may be fabricated and structured using a moulding technique.

[0115] FIGS. 5 and 6 depict part of an antenna mat assembly according to an embodiment of the invention. FIG. 5 shows a back view of a flexible sheet element as described with reference to FIGS. 4A and 4B. Planar antenna structures 6a,6b, in this example two patch antennas, a first patch antenna and a second patch antenna, are positioned in cavity 30a and cavity 30b respectively. Furthermore, a first coaxial transmission line 42 connected to the first patch antenna 6a is positioned in channel 32a and a second coaxial transmission line 44 connected to the second patch antenna 6a is positioned in channel 32b. As shown in FIG. 5, the substantially rectangular patch antenna may be positioned such that two sides of the antenna structure are substantially parallel to the longitudinal axis of the antenna mat (the outer sides of the antenna structure) and two sides of the antenna structure are substantially perpendicular to the longitudinal axis of the antenna mat (the inner sides of the antenna structure).

[0116] FIG. 6 schematically illustrates part of an antenna mat assembly (in this case a 3D back view). The assembly may include a flexible sheet element 25, planar antenna structures 6a,6b, coaxial transmission lines 42,44, antenna shielding layer 48 and a flexible cover sheet 46. The figure shows the antenna mat assembly upside down in the sense that the shown surface of cover layer 46 is positioned on the ground of the race track and faces the ground when the antenna mat 2 is unrolled across the race track. In one embodiment, cover layer 46 may comprise, (or essentially consists of), an elastomeric rubber, e.g. ethylene propylene diene monomer (EPDM) rubber. Preferably, an elastomeric rubber is selected that is durable and rough and which prevents the antenna mat 2 to slip or slide over the surface of the race track. Cover layer 46 is provided over the flexible sheet element comprising the planar antenna structures and the coaxial transmission lines and bonded to the surface of the flexible sheet element 25 in order to form a flexible sheet structure in which the planar antenna structures are embedded. Hence, the cover layer and the flexible sheet element may hermetically seal and protect the UHF elements from external (mechanical, thermal and/or electrical) influences.

[0117] A method for manufacturing the antenna mat may comprise moulding, e.g. low-pressure moulding, a flexible material into a structured flexible sheet element including recessed structures for planar antenna structures and coaxial transmission lines connected to the planar antenna structures, positioning the planar antenna structures and coaxial transmission lines into the recessed structures and sealing the antenna mat structure using the cover layer 46 (which may also be referred to as bottom layer). As such, the cover layer and the structured flexible sheet elements form a layered flexible sheet structure in which a plurality of planar antenna structures are embedded wherein a layered flexible sheet structure forms an antenna mat which can be rolled up.

[0118] In one embodiment, the antenna mat may comprise a conductive layer 48, e.g. a metal foil or a metallized film, which will be explained in more detail with reference to FIG. 7. Furthermore, FIG. 6 shows that a plurality of flexible sheet elements 25a, 25b may be physically connected to each other so as to form a flexible antenna mat of a desired length. In this embodiment, the flexible sheet elements connected by means of the protrusions 38 and cavities 40 described above.

[0119] It is submitted that structure of the antenna mat is not limited to the figures. For example, in further embodiments, instead of and/or in addition to the use of a flexible structured top sheet, the bottom layer may also include structures, e.g. recessed spaces and/or honeycomb structures, for embedding the antenna structures in the antenna mat and/or for providing a light flexible structure that has advantageous mechanical properties, e.g. in terms of (out of plane) compression stiffness and/or bending stiffness.

[0120] FIGS. 7A-7C and 8 depict a more detailed view of planar antenna structures according to various embodiment of the invention. As will be described hereunder in more detail, the antenna structures are configured such that they are particular robust against mechanical loads, in particular bending forces, due to the unwinding and the winding of an antenna mat roll. FIGS. 7A and 7B show exploded views of a planar antenna structure according to an embodiment. In this embodiment, the antenna structure may include one or more planar UHF antenna structure 6a,6b. FIG. 7C shows the antenna structure in its assembled state. These figures show the antenna from a top view in the sense that ground plate 52 is positioned closer to the race track than conductive patch 50 when the antenna mat is unrolled across the race track, i.e. when the antenna mat is in its operating position.

[0121] The planar UHF antenna structure may comprise at least one conductive plate 50 positioned above a conductive ground plane 52 and a spacer element 54 positioned between the conductive ground plane and the conductive plate. The planar UFH antenna structure is configured to generate a radiation field, wherein the radiation field may have a main axis that is substantially perpendicular to the conductive plate. Thus, at least a large part of the radiation field will be generated directly above the antenna structure in a direction perpendicular to the plane of the conductive plate. In an embodiment, the antenna structure includes a patch antenna, wherein the radiative element is conductive patch over a ground plane as e.g. depicted in FIG. 7, wherein the dimensions of the patch determine the radiative properties, e.g. the radiation frequency, of the antenna. In another embodiment, the antenna structure may include a slotted antenna. In such configuration the radiative element is (at least) one slot in a metal plate. In that case, the dimensions of the slot will determine the radiative properties, such as the radiation frequency of the antenna. The main shape of the conductive plate of the antenna may be rectangular. Other antenna configurations that depicted in the figures are also possible. For example, in an embodiment, an array of planar antenna structures, e.g. an array of patch and/or slotted antennas may be used. In another embodiment, a so-called planar inverted-F antenna (PIFA) may be used as a suitable planar antenna structure.

[0122] In addition, in an embodiment, a conductive shielding layer may be positioned under the antenna structures. The shielding layer which is electrically separated from the ground plane and the metal plate will shield the antenna structures from dielectrical and/or electromagnetical effects originating from objects and/or sources underneath the antenna mat. Further, the shielding layer will direct the radiation generation by the antenna structure in a direction normal to the shielding layer away from the ground.

[0123] The shielding layer may be connected to the ground plane 52 and is positioned substantially parallel to ground plane 52. The dimensions of the conductive foil 48 may larger than the dimensions of conductive ground plane 52 so that the conductive foil 48 can provide additional shielding for the patch antenna from external radiation and/or so that signals emitted by the patch antenna are directed upwards. The latter prevents that energy is wasted by transmitting electromagnetic radiation into the ground.

[0124] The shielding layer and the antenna plates, i.e. the conductive plate and the ground plate, may be made from any suitable conductive material, preferably a copper or another suitable metal.

[0125] As shown in the figures a coaxial transmission line is guided along the longitudinal axis of the antenna mat towards an antenna structure. When the transmission line approaches the antenna structure, the coaxial transmission line is guided in a direction that is substantially perpendicular to the longitudinal axis of the antenna mat and substantially parallel to an inner edge of the antenna structure. As will be described hereunder in more detail, the signal line of the coaxial transmission line is connected to a side of the conductive plate such that the mechanical load on the UHF connection due to the winding up and unwinding of the antenna mat roll is minimal.

[0126] The spacer structure 54 provides a stable separation between the ground plane and the conductive plate of the antenna. It is designed to inhibit changes to the separation due to pressure exerted on the antenna mat. In one embodiment, the spacer structure may comprise (or essentially consists of) a plastic, such as high-density polyethylene (HDPE).

[0127] One or more test devices 56a-56b, e.g. a passive tag, that, may be positioned in a fixed position with respect to an antenna structure 6a,6b. A test device 56 may be mounted on the spacer structure 54 or in a space in the spacer structure, e.g. pockets 58a, 58b, 58c, 58d. This way, the test device is positioned at a peripheral area of the antenna structure close to the radiation plate of the antenna.

[0128] FIG. 8 shows a top view of a planar antenna structure according to an embodiment of the invention. In this particular embodiment, each planar antenna structure 6a,6b may the antenna structure comprises a substantially rectangular plate 50a,50b. In one embodiment, dimensions of the plate may be selected so that the antenna radiates at a frequency in the Ultra High Frequency (UHF) range. The UHF range may include RF signals having a carrier frequency between 300 and 3000 MHz. In one embodiment, the planar antenna structures may be configured to transmit signals having a carrier frequency between 850 and 950 MHz. A dimension of the antenna structure, such as the width indicated by W, may approximately equals a half or a quarter wavelength associated with the carrier frequency of the antenna. Dimensions of the conductive plate (or in case of a slotted antenna) dimensions of a slot in a conductive plate (of a length L and width W) may be selected between 5 cm and 50 cm, preferably between 14 and 20 cm, more preferably between 15 and 18 cm.

[0129] As shown in FIG. 8 the conductive plate may be coupled to the coaxial transmission line via a microstrip 67. In an embodiment, at least part of the microstrip 67 may be formed by two slots 65a,65b which extend from an edge of the conductive plate 50b towards a center line 69 of the conductive plate. Such antenna structure may be referred to as a so-called inset microstrip line fed patch antenna. The thus formed inset feed may be used to match the impedances. For example, a (⅛)-wavelength inset would decrease the input impedance by 50% compared to a standard microstrip transmission line feed. Other types of feeds may also be used including but not limited to a quarter-wavelength transmission line feed, a probe feed, and/or an aperture feeds.

[0130] In one embodiment, the coaxial transmission lines may be configured as coax cables using a SubMiniature version A (SMA) type connector for connection e.g. the antenna controller. The inner conductor 60a, 60b, of the coaxial transmission line is connected to the conductive plate of the antenna structure. As depicted in the figure, at the connection point 60a,60b between the conductive plate and the transmission line 44,42, the longitudinal axis of the end of the transmission line (i.e. points A′ and A″ in FIG. 8) may be oriented substantially parallel to the axis of the antenna mat roll (i.e. parallel to the y-axis as shown in FIG. 8). This is achieved by one or more edge connectors 61,63 for mechanically connecting part of the end of the coaxial transmission line to an edge of the antenna structure close to the connection point at which the conductive plate of the antenna structure is connected to the coaxial transmission line. In an embodiment, the one or more edge connectors may be an integral part of the ground plate 54 as depicted in the figures. In that case, in an embodiment, the one or more edge connectors may also provide an electrical connection between the outer conductor (the ground) of the coaxial transmission line and the ground plate of the antenna structure. The one or more edge connectors enable the axis of the end of the coaxial transmission line to be parallel to the edge of the connection point 60a,60b. At the connection point, conductor plate 50a,50b may include a connector part which engages with the inner conductor of the coaxial transmission lines so that a mechanical and electrical stable UHF can be established between the conductor plate and the coaxial transmission line. Because the connection part is oriented parallel to the roll axis (which is parallel to the x-axis in FIG. 8) mechanical stress and wear on the UHF connection due to winding and unwinding the mat multiple times can be substantially reduced.

[0131] In an embodiment, antenna structures 6a and 6b may be a pair of patch antennas that is to be controlled to simultaneously emit signals (e.g. as described with reference to FIG. 2B). In that case, the coaxial transmission line 42 between an external controller and antenna structure 6b should have the same length as coaxial transmission line 44 between the external controller and antenna structure 6a in order to prevent that the two patch antennas emit signals asynchronously, e.g. to prevent that one of the patch antennas is emitting a signal whilst the other patch antenna is “listening” to signals. Such crosstalk due to signal skew may significantly distort measurements. Therefore, in one embodiment, the coaxial transmission lines connecting a pair of antenna structures to an antenna controller of equal length. Thus, the length of transmission line 44 at connection point 60a (point A′) and point B is equal to the length of transmission line 42 at connection point 60b (point A″) and point B, i.e. the position where both transmission lines meet. Preferably, the two transmission line follow the same trajectory from point B to a controller.

[0132] FIG. 9 shows of a planar antenna structure according to an embodiment of the invention. As shown in this figure, each planar antenna structure 6a,6b may include a spacer element 54a,54b for providing a spacing between a ground plane 52a,52b and a conductive plate 50a,50b. In an embodiment, the thickness of the spacer element (defining the spacing) may be selected between 3 and 9 mm. In this embodiment, the spacer structure 54a,54b may be structured on the basis of a honeycomb structure. In an embodiment, the honeycomb structure may include cells 55a-55c, wherein the geometry of the cells may include at least on of: hexagonal cell, triangular cells, triangular cells, square cells and/or combinations thereof. A cell size of a cell described herein may be understood to be the diameter of the largest circle that can be inscribed inside the cell with the circle touching one or more cell walls. In one embodiment, the cell sizes are in the range between 1 and 15 mm, preferably between 1 and 10 mm, more preferably between 1 and 8 mm. The honeycomb structure may be formed by a plurality of repeating units having a width and/or length in the range between 5 and 10 mm and preferably a height equal to the thickness of the spacer element. Each repeating unit may comprise one and only one cell. In some embodiments, these cells may include an additional circular structure. These cells may be referred to as circular-cored hexagonal, triangular or square-type cells. The conductive plate (the patch) and the conductive ground plane may be bonded to the honeycomb spacer element thereby forming a composite structure of excellent strength to weight ratio. The antenna structure is both light and possess an excellent resistance against bending loads when winding and unwinding the antenna mat roll. In one embodiment, the total weight of the antenna mat may be below 25 kilograms, preferably below 23 kilograms.

[0133] FIG. 10A depicts a rollable timing mat comprises a plurality of flexible structured sheet elements, e.g. at least three flexible sheet elements 25a, 25b and 25c as described with reference to FIGS. 4A and 4B. FIG. 10A further shows a plurality of side channels 62, 64, 66 along the edges of the longitudinal side of the flexible sheet elements. Each side channel may contain at least one coaxial transmission line for an antenna structure, e.g. an antenna pair, of a flexible sheet element. For example, side channel 62 may be configured to guide one or more coaxial transmission lines for the antenna structure of flexible sheet element 25a, trajectory 64 for the antenna structure of flexible sheet element 25b and trajectory 25c for the antenna structure of flexible sheet element 2c. One or more cross channels 35 in the flexible sheet elements may be used to reroute coaxial transmission lines from one side of the antenna mat to the other side of the mat. This way, a long antenna mat may be formed. FIG. 10B illustrates a timing mat assembly including an antenna mat 2 that is mechanically and electrically connectable to a roll structure 10 (e.g. a reel). In the figure, timing mat 2 is at least partially wound around the cylinder body 10, e.g. an aluminium or plastic body. Additionally, FIG. 10B shows (bottom) the timing mat 2 in an unrolled state. FIG. 10B illustrates the ease with which the timing mat can be installed across a race track. A user simply has to position the cylinder body 10 around which the timing mat is wound, at one side of a race track. Then, installation merely involves rolling the cylinder body such that the timing mat unrolls and is positioned on the race track. This does not involve any dragging of parts of the timing mat over the ground.

[0134] FIG. 11 shows an embodiment wherein at least two timing mats 2a and 2b as e.g. depicted in FIG. 4B are positioned against each other. For clarity, only the cavities 40 are shown. The cavity 40a of timing mat 2a and the cavity 40b of timing mat 2b together form a further cavity. Optionally, as in this example, the cavity 40a′ of timing mat 2a and cavity 40b′ of timing mat 2 also form a further cavity. The two timing mats may be connected to each other by placing a connector in the cavity as formed by the two cavities 40a and 40b. If applicable, a second connecter can be placed in the cavity that is formed by cavities 40a′ and 40b′. As such, even further timing mats can be produced, for example more than six timing mats can be connected to each other even if each sub-timing mat only comprises a total of six side channels. In an example, the connector is thus shaped as a dog bone. Further, the connector may be EPDM or SBR rubber.

[0135] FIG. 12A-C illustrate antenna mat assemblies according to various embodiments of the invention. In particular, the antenna mat assembly may include an antenna mat in a rolled-up state positioned on a carrier, e.g. a hand truck or a dolly, 70 for transporting lifting and transporting an antenna mat roll. In the rolled-up state, the antenna mat may be wound around a cylindrical roll 10, preferably a hollow roll. In this state, the antenna mat wound around the roll may be referred to as an antenna mat roll.

[0136] As shown in the figures, the hand truck may include a shaft 11 wherein a first end of the shaft is connected to a base 13 and the second end of the shaft include one or more handles 15. As shown in FIGS. 12B and 12C, at least two wheels 76 and a ledge 72 may be connected to the base. In an embodiment, the ledge may be cylindrically curved this way the ledge may form a scoop for supporting part of the cylindrical surface of the antenna mat roll 2 (as shown in FIG. 12C). The cylindrical curvature of the ledge matches the cylindrical curvature of the antenna mat roll so that the ledge can be easily inserted underneath the antenna mat roll. This way, the shaft can be used to lift the antenna mat roll from the ground.

[0137] The cylindrically curved ledge of the hand truck provides a stable support surface for carrying the antenna mat roll in an orientation wherein the roll axis of the antenna mat roll may be parallel to an axis 77 connecting the center of the wheels. This way, the antenna mat roll may be easily lifted and transported to a desired location. In an embodiment, the shaft may include a support structure 74 that can be used for supporting a separate box 19 comprising an antenna mat controller.

[0138] FIG. 13A-13D illustrate antenna mat assemblies according to various embodiments of the invention. In particular, the antenna mat assembly may include an antenna mat roll positioned on a carrier, e.g. a hand truck or a dolly, 80,82 for transporting lifting and transporting an antenna mat roll. As shown in the figures, also in these embodiments, the carrier may include a shaft 84 wherein a first end 85 of the shaft may be connected to a base. At least two wheels 90a,90b and a ledge 86 may be connected to the base, wherein the ledge is configured to support the antenna mat roll. The second end of the shaft may include one or more handles 88 allowing a user to handle the carrier. In this particular embodiment, the ledge may be structured as a rectangular tray where the shaft may be connected to a first side of the rectangular tray and wherein the at least two wheels may be connected to the tray such that the axis 91 connecting the center of the wheels is parallel to the first side of the tray.

[0139] In an embodiment, the antenna mat roll may be positioned in the tray such that the roll axis 94 of the antenna mat roll may be parallel to the axis 91 connecting the center of the two wheels. The tray may include rising edges 92a,92b positioned along the sides of the tray wherein the rising edges are configured to stop the antenna mat from sliding of the tray during transportation. In an embodiment, the height of one rising edge, e.g. the rising edge 92b at a second side opposite to the first side, may be lower than the height of the rising edges along the other (three) rising edges of the tray.

[0140] In an embodiment, a first frame structure 96a connected to the tray is positioned along a second side of the tray and a second frame structure 96b connected to the tray is positioned along a third side of the tray (opposite to the second side of the tray), wherein the second and third sides of the tray are perpendicular to the first side of the tray. The height of the first and second frame structure is higher that the height of the antenna mat roll positioned in the tray. Further, in an embodiment, the second end of the shaft may be connected to the base using a detachable connection structure. Thus, in this embodiment, the shaft may be detached resulting in an assembly comprising an antenna mat roll positioned in the tray including first and second frame structures, which enables a user to easily handle and lift the antenna mat roll.

[0141] As shown in FIGS. 13C and 13D in an embodiment, the first and second frame structures may be a closed structure so that it can protect the sides of the antenna mat roll, which in some embodiment may include electrical UHF connectors and/or sports timing electronics including e.g. a controller, for electrically controlling the antenna mat.

[0142] When removing the shaft of the antenna mat assembly as depicted in FIG. 13D, the resulting assembly comprising an antenna mat roll positioned in the tray including first and second frame structures, may be configured as a stackable antenna mat assembly. This is illustrated in more detail in FIG. 14A-14B, which depict stacked antenna mat assemblies according to various embodiments of the invention. In particular, these figures illustrate a stacked antenna mat assembly 100 comprising (in this particular case) a first stackable antenna mat assembly 102a and a second stackable antenna mat assembly 102b. Each stackable antenna mat assembly may include a tray structure (i.e. first tray structure 104a and second tray structure 104b) configured to support an antenna mat roll 106a,106b as described in detail with reference to FIG. 13A-13D.

[0143] The tray structure may be a substantially rectangular tray structure including four sides, wherein a first side may include a connector 101 for removably connecting a shaft connected to a handle (as described with reference to FIG. 13A-13D). Further, an antenna mat assembly may include a first frame structure 108a,108b connected to the tray, wherein the first frame structure is positioned along a second side of the tray, and a second frame structure 110a,110b connected to the tray which is positioned along a third side of the tray structure (opposite to the second side of the tray). As shown in these figures, the top part of the first and second frame structures 108b,110b of the second stackable antenna mat assembly may be shaped to engage with corresponding mechanical coupling parts 112a of the first tray structure of the first stackable antenna mat assembly. As shown in the figure, in an embodiment, the mechanical coupling parts may include a first recess and second recess 112a in the tray structure 104a. Thus, the antenna mat assemblies depicted in FIGS. 13 and 14 allow easy transportation, storage and installing and deinstalling of finish lines of a sports timing system of a sport event.

[0144] The structures and assemblies depicted in the figures are non-limiting and are used for illustrating the advantageous features and functionalities provided by the invention. Many other variants of the embodiments are possible without departing the essence of the invention. For example, FIG. 15 schematically depicts an embodiment of the invention including an antenna mat roll rotatable mounted in a reel or winder structure. The reel structure may include a frame, e.g. a tubular frame, in which the antenna mat roll is rotatable mounted. At least one of the side faces of the roll may include a handle 120 for rolling and unrolling the antenna mat. Further, in an embodiment, an antenna mat controller may be provided in the hollow space of the roll. A least one of the side faces of the roll may include at least one graphical user interface (GUI) of the antenna mat controller.

[0145] Similarly, FIG. 16A-16C depict stackable antenna mat roll structures according to an embodiment of the invention. In this embodiment, the roll structure 130a,130b of the antenna mat roll may include structured edges along the periphery of the basis of the cylindrical roll. For example, first roll structure 130a may include a first (top) edge 132a and a second (bottom) edge 134a and second roll structure 130b may include a first (top) edge 132b and a second (bottom) edge 134b. The edges may be structured so that the antenna mat rolls can be stacked as depicted in FIGS. 16B and 16C. For example, a first circular (top) edge of a first roll may include one or more recesses and a second circular (bottom) edge of a second roll may include one or more ledges which are configured to engage with the one or more recesses of the first roll. This way, when positioning the second roll structure on top of the first roll structure, the first edge structure of the first roll structure engages with the second edge structure of the second roll structure. Hence, this way, the antenna mat rolls can be stacked on top of each other with their cylindrical axis perpendicular to the ground surface.

[0146] Some embodiments of the invention may be implemented as a program product for use with a computer system, where the program(s) of the program product define functions of the embodiments (including the methods described herein). In one embodiment, the program(s) can be contained on a variety of non-transitory computer-readable storage media, where, as used herein, the expression “non-transitory computer readable storage media” comprises all computer-readable media, with the sole exception being a transitory, propagating signal. In another embodiment, the program(s) can be contained on a variety of transitory computer-readable storage media. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., flash memory, floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. The computer program may be run on the processor 1002 described herein.

[0147] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0148] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of embodiments of the present invention has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present invention. The embodiments were chosen and described in order to best explain the principles and some practical applications of the present invention, and to enable others of ordinary skill in the art to understand the present invention for various embodiments with various modifications as are suited to the particular use contemplated.

[0149] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0150] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.