Abstract:
The subject matter relates to methods for communicating with an RFID tag that is positioned out of the line-of-sight of a communications device. A passive reflector is provided corresponding to an antenna resonant at the operating frequency of the tag. The antemia may be supported by an insulative or conductive wand for manual placement within the line-of-sight of both the tag and a communications device wishing to communicate with the tag. The passive reflector receives signals from either or both the tag and communications device and retransmits the signals. In this manner signals are able to “turn a comer” to improve communications capabilities.

Description:
FIELD OF THE INVENTION 
       [0001]    The present subject matter generally relates to tire tags and related tire electronics, and more particularly concerns an antenna and methods for using such antenna. 
       BACKGROUND OF THE INVENTION 
       [0002]    The incorporation of electronic devices with pneumatic tire structures yields many practical advantages. Tire electronics may include sensors and other components for obtaining information regarding various physical parameters of a tire, such as temperature, pressure, number of tire revolutions, vehicle speed, etc. Such performance information may become useful in tire monitoring and warning systems, and may have potential use as a part of a feedback system to regulate or control certain tire and/or vehicle related systems. Yet another potential capability offered by electronics systems integrated with tire structures corresponds to asset tracking and performance characterization for commercial vehicular applications. 
         [0003]    Sensors using piezoelectric-based technology have been used in various tire embodiments for a variety of purposes. For example, piezoelectric elements have been used to generate power within a tire. Piezoelectric sensors have been used to function as a revolution counter within a tire. Piezoelectric sensors have even been used to determine deflection, acceleration and other parameters. 
         [0004]    Some of these devices include radio frequency (RF) features and may correspond to tags that may be described as RFID tags. Such RFID tags may be used in a number of ways including for identification by way of serial number, for example, of a particular tire. Additional information may be provided such as manufacturing location and date, information regarding tire construction and type, manufacturer&#39;s name, etc. 
         [0005]    One aspect of such RFID tags is that information must be read from the tag by way of radio frequency signals. It has been found, however, that truck tires, for example, in which such tags are placed absorb or block RF energy. In such instances it may become difficult to read an RFID tags located, for example, on the inside sidewall of the inside tire of dual-mounted tires. 
         [0006]    Current methods for reading such tags generally involve one of three strategies: (1) Extending an antenna that is electrically connected to the RFID transponder into the wheel well so that it is within line-of-sight of the tag; (2) Physically hold a complete but compact RFID transponder inside the wheel well so that the built-in antenna is within line-of-sight of the tag; or (3) Using an RFID transponder with the maximum allowed power and antenna gain, and read the tag by means of reflections off portions of the truck frame and suspension components, etc. This last approach is simple, but not reliable as reflections are very random. The first two approaches have drawbacks of ergonomics, cost, and fragility. 
         [0007]    Although many tire tag reading arrangements have been developed, a need remains for a robust and reliable method for reading tire tags positioned in difficult to access locations. No design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology. 
       SUMMARY OF THE INVENTION 
       [0008]    In view of the recognized features encountered in the prior art and addressed by the present subject matter, improved methodologies have been developed to more easily read RFID tags located in less accessible locations. 
         [0009]    One exemplary embodiment of the present subject matter relates to a method for reading a hidden tag positioned out of line-of-sight of a tag reader. The method includes providing an antenna that is resonant at the operating frequency of the tag and a receiver capable of receiving signals at the operating frequency of the tag. The antenna is positioned at a location within the line-of-sight of both the tag and the receiver so that signals from the tag will be received by the antenna and re-transmitted thereby to the receiver. 
         [0010]    In certain embodiments the antenna is temporarily manually positioned and may be supported by an insulative wand or conductive wand, which, in either instance may be provided as an extendable wand. In instances where the wand is conductive, the antenna may be electrically coupled to the wand. In particular embodiments, one end of the wand may be mechanically coupled to the receiver for ease of supporting the antenna. 
         [0011]    Another exemplary embodiment of the present subject matter relates to a method for communicating with a hidden radio frequency (RF) tag. Such method includes providing an antenna resonant at the operating frequency of the tag and a transceiver capable of transmitting and receiving signals at the operating frequency of the tag. In accordance with such method the antenna is positioned at a location within the line-of-sight of both the tag and the transceiver so that signals exchanged between the tag and the transceiver will be received by the antenna and re-transmitted. 
         [0012]    Yet another exemplary embodiment of the present subject matter relates to a method for providing a passive reflector for an RFID tag. In such method an antenna is provided that is resonant at the operating frequency of the RFID tag and secured to a first end of a manually supportable wand. In certain embodiments the wand may be an extendable wand. In selected embodiments, the wand may be a conductive wand that, in selected embodiments, may be electrically connected to the antenna. 
         [0013]    Additional embodiments of the present subject matter, not necessarily expressed in the summarized section, may include and incorporate various combinations of aspects of features, components, or steps referenced in the summarized embodiments above, and/or other features, components, or steps as otherwise discussed in this application. Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
           [0015]      FIG. 1  provides an illustration of an exemplary passive reflector in accordance with present technology; 
           [0016]      FIG. 2  illustrates a methodology by which the present technology is employed to enable reading of an out-of-sight tire tag; 
           [0017]      FIG. 3  illustrates positional relationships for a passive reflector to best repeat signals from a hidden tag; 
           [0018]      FIG. 4  illustrates an alternate embodiment of a passive reflector in accordance with present technology; 
           [0019]      FIG. 5  illustrates a further embodiment of a passive reflector constructed using a retractable support; 
           [0020]      FIGS. 6 and 7  illustrate further embodiments of a passive reflector constructed using collapsible supports; 
           [0021]      FIGS. 8A-8D  illustrate various possible positional relationships between an antenna element and a support structure; and 
           [0022]      FIGS. 9A-9D  illustrate various possible collapsible support and antenna arrangements with various storage possibilities for the antenna element. 
       
    
    
       [0023]    Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features, elements or steps of the present invention. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    As discussed in the Summary of the Invention section, the present subject matter is generally concerned with methods for reading information from RFID tags located in less accessible locations of mounted tires. In more particular embodiments, repeater antenna systems are provided to make a less accessibly located tag readable using conventional handheld readers located in positions that, absent the present technology, would not be able to read the tags. 
         [0025]    Selected combinations of aspects of the disclosed technology correspond to a plurality of different embodiments of the present invention. It should be noted that each of the exemplary embodiments presented and discussed herein should not insinuate limitations of the present subject matter. Features or steps illustrated or described as part of one embodiment may be used in combination with aspects of another embodiment to yield yet further embodiments. Additionally, certain features may be interchanged with similar devices or features not expressly mentioned which perform the same or similar function. 
         [0026]    Referring now to the drawings,  FIG. 1  is an illustration of an exemplary passive reflector  100  in accordance with present technology. Passive reflector  100  corresponds to a tuned antenna  110  mounted to one end of a support element  120 . Passive reflector  100 , in operation, functions as a “passive repeater” in that antenna  110  when placed proximate a transmitting device receives and re-radiates a signal to which antenna  110  is tuned. Generally, the combination of antenna  110  and support element  120  may be viewed as an entirely portable wand with a passive repeating antenna configured to allow positioning of the antenna portion of the combination in real time to a location to provide a temporary repeating functionality that here-to-fore has not been available. 
         [0027]    Referring now to  FIGS. 2 and 3 , there are illustrated exemplary placements  200 ,  300  for an antenna  210 ,  310  and wand  220 ,  320  to illustrate an advantageous placement of tuned antenna  210 ,  310  for best repeater functionality. As may be seen in both  FIGS. 2 and 3 , antenna  210 ,  310  is to be placed in proximity to a hidden RFID tag  340  more generally illustrated in  FIG. 3  while the hidden tag may be located, for example, in the sidewall of an inside tire of dual-mounted tires in the wheel well of a large truck. As more generally illustrated in  FIG. 2 , hidden tag  340  will, upon initially receiving an interrogation signal from transceiver  230 , will modulate and re-radiate such received signal as radio frequency signals  232  that are received by tuned antenna  210 ,  310  and again re-radiated or re-transmitted as signals  234  toward transceiver  230 ,  330 . 
         [0028]    Due to its resonant nature, the passive reflector antenna collects a portion of the energy radiated by hidden tag  340  and re-transmits it according to its own antenna gain pattern. In this manner, some of the RF energy re-radiated by hidden tag  340  has now effectively “turned a corner” finding a path from the hidden tag to transceiver  230 ,  330 . Similarly as previously noted, in instances where transceiver  230 ,  330  transmits a signal to hidden RFID tag  340 , such transmitted signal may also be re-directed around the corner formed by tire  360  by use of present technology to provide increased energy and/or signals to hidden tag  340 . 
         [0029]    It is noted here that transceiver  230 ,  330  may generally be regarded as a receiver in that such device is configured to receive re-radiated signals from tag  340 . Those of ordinary skill in the art will appreciate, however, that in most instances RFID tags are formed as otherwise passive devices in that they do not have their own power supply but rather are configured to re-modulate a received signal or extract power from a received signal to transmit data to a receiver. In these instances, transceivers  230 ,  330  are also operated as a transmitter to query or interrogate the tag or simply to supply RF energy that the tag then uses to power itself. 
         [0030]    In either instance, that is, for receiving signals from tag  340  or transmitting signals to tag  340 , the methodologies as taught by the present technology are useful to repeat the signals passed from one of the devices to the other when the respective items may be blocked from a line-of-sight view of each other thereby reducing signal strength there between. 
         [0031]    With more specific reference to  FIG. 3 , an operator wishing to read signals from hidden RFID tag  340  may hold wand  320  in one hand and transceiver  330  in the other hand so as to position antenna  310  in a zone  350  extending generally above hidden tag  340  and behind the inner tire  360  of dual-mounted tires  360 ,  362 . As the hidden tag  340  is “hidden,” some amount of “fishing” for the best signal reception may be required including lateral movement within zone  350 . As an alternative to holding transceiver  330  in one hand and wand  320  in the other, wand  320  may be temporarily or permanently attached to transceiver  330  to facilitate performing the entire operation with one hand. 
         [0032]    With further reference to  FIGS. 1-3 , antenna  110 ,  210 ,  310 , may in each instance correspond to a half-wavelength dipole antenna while support (wand)  120 ,  220 ,  320  may correspond to an insulating wand. In exemplary configurations, antenna  110 ,  210 ,  310  may correspond to a copper wire or an equivalent that is conductive at the RFID frequency. In an exemplary configuration, the RFID frequency may correspond to commonly used such frequencies that vary by governmental regulations depending on the country in which the device is operated. In the United States, the frequency may be approximately 915 MHz while in Europe the frequency may be approximately 868 MHz. In exemplary configurations, a resonant 915 MHz antenna may be provided by a 158 mm length of 14-gauge antenna wire while a similar 868 MHz resonant antenna may be provided by a 166.5 mm length of 14-gauge antenna wire. 
         [0033]    In other embodiments, antenna  110 ,  210 ,  310  may take different forms and may include such as a coiled wire helix, a coiled steel helical spring that may be coated with copper and nickel, or constructed using circuit traces on a printed circuit board. Coiled conductor configuration permis shorter overall antenna structures. In certain instances, coiled conductors may be embedded in or touching a dielectric material. Further discussion on this possibility will be provided with respect to the embodiment of  FIG. 4 . It is noted here, however, that such contact or near contact with a material having a dielectric constant and/or magnetic permittivity greater than air will also shorten the resonant length. One example of such is a coiled antenna embedded in a flexible dielectric sometimes referred to as a “rubber ducky” antenna used on walkie-talkies, etc. In all instances, however, the antenna is tuned to, that is, is resonant at, the operating frequency of the RFID tag. 
         [0034]    As to support (wand)  120 ,  220 ,  320 , such structure may correspond, in some embodiments, to a insulated support such as a fiberglass pole similar to a fishing pole. Other material may also be used including wood and plastic. One desirable characteristic for such a support includes at least slight flexibility to avoid breakage. Flexibility may be achieved in a number of ways including selection of material used along with physical measurements like diameter or cross-section. 
         [0035]    With reference now to  FIG. 4 , there is illustrated an alternate embodiment of a passive reflector  400  in accordance with present technology. In accordance with the embodiment of the present subject matter illustrated in  FIG. 4 , the support or wand may correspond to a two-piece construction including a conductive portion  420  and an insulated portion  430  that may made of plastic. Insulated portion  430  may be configured in a “V” shape to receive conductive portion  420  that may correspond to a conductive wire, for example, a copper wire similar or identical in composition to antenna  410  and may be soldered thereto. Insulated portion  430  may then be held in an operator&#39;s hand without adversely effecting the directional operation of conductive portion  420 . 
         [0036]    In an alternative configuration, steel or aluminum may be used for conductive portion  420 . Yet additional alternative configurations of an insulated portion  430  supporting a conductive portion  420  may be provided. For example, a portion of PVC tubing may be used to support a conductive portion inserted into the tubing. Alternatively yet, a conductive wire encased in a fiberglass covering may be used where an exposed portion of the wire may be soldered to the antenna. In this configuration, it has been found that conductive portion  420  will act in part as a “director” element for antenna  410  to increase the amount of signal conveyed between the tag and transceiver. 
         [0037]    In a preferred embodiment, the antenna is made of copper or copper alloy, but other good conductors could also be used. At UHF frequencies, electromagnetic waves are carried on the surface layer of a conductive material. Therefore, the antenna can be physically made of steel or other materials that do not conduct well at UHF and coated with a few microns of highly-conductive material to provide the wave carrying surface layer. 
         [0038]    It has been found that a conductive wand gives a significantly better result than a non-conductive one. However the exact length of the wand does not seem to be important thus any length wand is acceptable. Similarly, the exact location of the transceiver (reader) placement along the wand also does not seem to be important so that any placement is acceptable. 
         [0039]    Referring now to  FIGS. 5-9 , a number of different configurations for an antenna and support structure are illustrated, all with the object of illustrating portable configuration of devices usable with the present technology that may be collapsed into a smaller package for ease of portability and/or storage. 
         [0040]    With reference to  FIG. 5 , there is illustrated a device  500  in the form of a wand  520  containing a measuring tape  524  that may be retracted for portability and storage. Antenna  510  may be attached by insulated tape  522  to an exposed end of tape  524 . The combined device may then be used in the same manner as the various devices illustrated in  FIG. 1-4 . 
         [0041]      FIG. 6  illustrates a device  600  corresponding to a telescoping support  620  having antenna  610  coupled to one end thereof. Telescoping support  620  may correspond to, for example, a lecturer&#39;s pointer or a telescoping antenna for example as used on portable radios or television receivers. 
         [0042]      FIG. 7  illustrates yet another embodiment of a device  700  including an antenna  710  coupled to one end of a foldable support structure  720 . Folding support structure  720  may correspond in function to, for example, a folding carpenter&#39;s ruler. Generally for telescoping or foldable configurations, the support portion of the device should range from about 30″ to about 48″ long when the device is to be used to assist in reading RFID tags on the inside sidewall of the inside tire in dual-mounted tires. When used in other situations, the wand might be shorter or longer as required. 
         [0043]    In some instances it may be that a collapsible wand is not required. In those cases, other possibilities are available such as providing a permanent bend built into the wand, or making all or part of the wand from a material or composition that can be semi-permanently deformed, for example, in a manner similar to that of a gooseneck lamp. 
         [0044]    Alternatively still, while the antenna placement is preferably balanced, centered on the end of the wand, it is possible for the antenna to work, albeit at reduced efficiency, if it is somewhat offset, even to the extent of being supported at one end.  FIGS. 8A-8D  illustrate such possibilities including the preferred centered, perpendicular configuration of  FIG. 8A , end support configurations in  FIGS. 8B and 8D  and centered but non-perpendicular to the wand in  FIG. 8C . In the configuration of  FIGS. 8C and 8D  where antenna  810  is not perpendicular to wand  820 , the angle between the wand and antenna may vary up to as much as 30-45 degrees without serious loss of efficiency. 
         [0045]    In certain embodiments, it may be desirable to provide a way to collapse the entire structure into a small package which is easy to carry, for example in a pocket, rugged, that is not easily damaged, and easy to deploy quickly. Given the present disclosure, those of ordinary skill in the art will be able to imagine many options for achieving these goals, but several non-limiting examples may be seen in  FIGS. 9A-9D . 
         [0046]    In  FIG. 9A , telescoping support  920  provides support for foldable antenna  910 . In such embodiment, antenna  910  may be folded in the direction of the arrows against the body of a collapsed telescoping support  920 . 
         [0047]      FIG. 9B  illustrates a similar configuration except that antenna  910  is configured to pivot around its mid-portion so as to be positioned parallel to the body of a collapsed telescoping support  920 . 
         [0048]      FIG. 9C  provides an alternate configuration where antenna  910  is configured to slide in the direction of arrow  1 , rotate in the direction of arrow  2  and then be inserted into the end of telescoping support  920  as indicated at arrow  3 . 
         [0049]    Finally, as illustrated in  FIG. 9D , antenna  910  may be disconnected from support wand  920  and then secured to the side of the body of a collapsed telescoping support  920 . Detached antenna  910  may be secured using a clip or other type fastener or the antenna might be separately stored. 
         [0050]    In general with all of the various embodiments described, the antenna can be insulated from the wand or bonded to it electrically. Further the antenna may be held to the end of the wand by any of several ways including, without limitation, by a clip, threaded fastener, rivet, magnet, sleeve, loop, adhesive, and adhesive tape. 
         [0051]    In those instances where a folding construction is chosen, it is important to maintain good electrical conductivity between the two folding halves of the antenna. Such could be done with appropriate metals and a sliding junction at the pivot point, with a mechanism to maintain a consistent normal force at the pivot; or could be done with a short, highly flexible and fatigue-resistant “jumper wire” connected between the two halves of the antenna. 
         [0052]    In still further configurations, the antenna could be configured as a multi-elements antenna or some other configuration, for example, a patch antenna, that would give it additional desirable RF directivity. Such gain, however, would come at the expense of increased size and weight at the end of the wand, but may be advantageous in certain circumstances because it could increase the strength of the signal path between the transponder and tag. 
         [0053]    While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.