Abstract:
An annular antenna and transponder are affixed to a tire using the transponder as a counterweight to offset tire imbalance. The annular antenna is attached to an inner tire surface and is coupled electrically to a transponder device and is fixed relative to a housing in which the transponder device is packaged. The mass of the transponder housing is used specifically to counterbalance tire imbalance by first ascertaining the position at which a counterbalance would prove to be beneficial and then affixing the annular assembly to the tire so as to position the mass of the transponder housing at the optimal location for counterbalancing benefit.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates generally to an annular apparatus, including an antenna and a transponder, useful in a tire for the purpose of transmitting tire or wheel data and, more specifically, to the method of assembly thereof.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is common to employ annular apparatus, including an antenna, for electronically transmitting tire or wheel identification or other data at radio frequency. The apparatus includes a radio-frequency transponder comprising an integrated circuit chip having data capacity at least sufficient to retain identification information for the tire or wheel. Other data, such as the inflation pressure of the tire or the temperature of the tire or wheel at the transponder location, can be transmitted by the transponder along with the identification data.  
         [0003]     It is known in the art to employ an annular antenna to transmit, at radio frequencies, data from a transponder contained within the structure of a tire or tire and wheel assembly. The antenna and transponder may be incorporated into a tire during “pre-cure” manufacture. In practice, however, it is very difficult to do this. Both radial ply and bias ply tires undergo a substantial diametric enlargement during the course of manufacture. Bias ply tires are expanded diametrically when inserted into a curing press, which typically has a bladder that forces the green tire into the toroidal shape of the mold enclosing it. Radial ply tires undergo diametric expansion during the tire building or shaping process and a further diametric expansion during the course of curing. Any annular antenna and the electronic circuitry associated therewith built into the tire must be able to maintain structural integrity and the mechanical connection between the antenna and transponder package during the diametric enlargement of the tire during its manufacture. Once assembled into the tire, any detected malfunction in the antenna, transponder, or antenna to transponder connection that cannot be repaired destroys the utility of the tire and may necessitate a scrapping of the tire. Hence, placement of an annular antenna-transponder assembly into a tire during its manufacture carries risk that subsequent failure or breakage of assembly components will necessitate the destruction of the otherwise suitable host tire.  
         [0004]     Not only is the risk of damage to an annular antenna-transponder system present during its incorporation into a tire during manufacture, but damage to such systems are not uncommon from operation of the tire on a vehicle. Loop antennas in known tire pressure monitoring systems have heretofore been placed into the tire during the curing process either at the crown of the tire, the bead of the tire, or the sidewall. Antennas and transponders located in the crown are subjected to substantial compressive strain and at the sidewall a high strain amplitude. Such locations represent high load and deformation regions of the tire. Consequently, antenna, transponders, and the connections therebetween in such locations are prone to breakage and mechanical or electrical failure.  
         [0005]     Because of the nature of the tire building process, it is not uncommon for a manufactured tire to have an imbalance that will eventually require an offset through the use of a counterbalancing weight. An annular antenna-transponder system likewise represents an imbalanced system in that the weight distribution resulting from the transponder package is asymmetrical. The weight of the transponder or sensor, when attached to a tire, can reinforce the inherent imbalance of the tire and create the need for increased counterweighing measures.  
         [0006]     A need therefore exists for a method and apparatus for mounting a transponder module in a pneumatic tire in such a manner that the transponder does not exacerbate the inherit imbalance of the tire.  
         [0007]     Still a further need exists to provide a method for mounting a transponder module in a pneumatic tire at any point in the tire manufacturing process in a manner that will enhance tire performance and longevity.  
         [0008]     In addition, a need exists to provide a method for attaching an annular apparatus including an annular antenna and transponder in a cost effective and efficient manner.  
       SUMMARY OF THE INVENTION  
       [0009]     The subject invention satisfies the needs of the industry for an improved annular apparatus and method for affixing a transponder to a tire. According to one aspect of the invention, a tire having an annular antenna and transponder apparatus is provided. The tire is analyzed to determine the location of tire imbalance. The annular transponder apparatus is attached to the tire in such a manner to strategically place the transponder to offset the imbalance of the tire. A method of attaching the antenna and transponder apparatus is provided as a further aspect of the invention, comprising the steps: identifying the location of tire imbalance in a tire; attaching an annular antenna and transponder assembly to the tire so that the transponder is placed to offset the imbalance of the tire.  
         [0010]     The advantages of the invention, which will be apparent to those skilled in the art, are achieved by preferred and alternative embodiments that are described in detail below and illustrated by the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a perspective view of a tire and the subject annular apparatus with portions of the tire removed for the purpose of illustration.  
         [0012]      FIG. 2  is a sectional schematic of a tire mounted to a rim and illustrating alternative locations in which to mount the subject annular apparatus.  
         [0013]      FIG. 3  is an enlarged perspective view of a tire portion having a transponder and antenna assembly positioned against a tire sidewall surface.  
         [0014]      FIG. 4  is a sectional schematic view of a tire and wheel assembly mounted to a vehicle frame.  
         [0015]      FIG. 5  is an enlarged perspective view of the subject antenna projecting through a transponder module.  
         [0016]      FIG. 6  is an enlarged perspective view of a transponder portion of the subject annular assembly.  
         [0017]      FIG. 7  is an exploded perspective view of the subject transponder module.  
         [0018]      FIG. 8  is a top plan view thereof.  
         [0019]      FIG. 9  is a longitudinal section view through the transponder module of  FIG. 9  taken along the line  9 - 9 .  
         [0020]      FIG. 10  is a transverse section view through the transponder module of  FIG. 9  taken along the line  10 - 10 .  
         [0021]      FIG. 11  is a perspective view of a representative module circuit board.  
         [0022]      FIG. 12  is a block diagram of the transponder to transceiver coupling system.  
         [0023]      FIG. 13  is a perspective view of a portion of the antenna and showing application of an adhesive material thereto.  
         [0024]      FIG. 14  is a perspective view of a portion of the antenna and the transponder and showing application of the adhesive material.  
         [0025]      FIG. 15  is a block diagram showing the method of annular transponder apparatus installation pursuant to the invention. 
     
    
     DEFINITIONS  
       [0026]     “Axial” and “axially” means the lines or directions that are parallel to the axis of rotation of the tire.  
         [0027]     “Bead” or “bead core” generally means that part of the tire comprising an annular tensile member of radially inner beads that are associated with holding the tire to the rim; the beads being wrapped by ply cords and shaped, with or without other reinforcement elements.  
         [0028]     “Circumferential” most often means circular lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial directs; it can also refer to the direction of the sets of adjacent circular curves whose radii define the axial curvature of the tread, as viewed in cross section.  
         [0029]     “Inner” means toward the inside of the tire and “outer” means toward its exterior.  
         [0030]     “Lateral” means in a direction parallel to the axial direction.  
         [0031]     “Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire.  
         [0032]     “Shoulder” means the upper portion of sidewall just below the tread edge.  
         [0033]     “Sidewall” means that portion of tire between the tread and the bead.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]     As used herein, a “transponder” is an electronic apparatus (device) capable of monitoring a condition such as air pressure within a pneumatic tire, and then transmitting that information to an external device. The external device can be either an RF (radio frequency) reader/interrogator or, simply an RF receiver. A simple receiver can be used when the transponder is “active”, and has its own power source. A reader/interrogator would be used when the transponder is “passive” and is powered by an RF signal from the reader/interrogator. In either case, in conjunction with the external device, the transponder forms a component of an overall tire-condition monitoring/warning system. A toroidal body composed of a material of high electromagnetic permeability is coupled to the transponder by a winding. In conventional systems, the antenna is coupled to the toroidal body by means of a primary winding and the transponder is coupled to the toroidal body by means of a secondary winding. As explained below, the primary winding may be eliminated. The “secondary” winding that couples a transponder to the toroidal body hence is referred to herein as merely the “winding”. For the purpose of the subject disclosure and the invention, the annular system is not transponder specific. That is, a wide range of commonly available transponders, sensors, and associated electronics may be packaged and utilized with the subject invention.  
         [0035]     As used herein, a “toroid” is a body formed from material having a high elector-magnetic permeability by a continuous curved surface and includes a central through bore. The toroidal body may be cylindrical, oblong, symmetrical, or asymmetrical without departing from the invention herein set forth. As used herein, a “toroidal body” thus includes a transformer having one or more windings.  
         [0036]     In order to send or receive RF signals, a transponder must have an antenna. The antenna is annular in configuration in the subject invention and may either be incorporated into the tire during manufacture or affixed to the tire by way of a post manufacture procedure. As used herein, an “annular antenna” may be circular, oblong, symmetrical, or asymmetrical without departing from the subject inventive principles. However, the preferred configuration of the antenna is circular and sized to overlap the tire sidewall region to which it attaches. The antenna may comprise a single wire or a plurality of strands. Various commercially available transponders, sensors, and other electrical devices deployed in combination with an annular antenna formed from conventional conductive materials are suitable for use in conformance with the principles of the subject invention.  
         [0037]     Acceptable materials for the antenna wire include steel, aluminum, copper or other electrically conducting wire. As disclosed in this patent document, the wire diameter is not generally considered critical for operation as an antenna for a transponder. For durability, stranded steel wire consisting of multiple strands of fine wire is preferred. Other wire options available include ribbon cable, flexible circuits, conductive film, conductive rubber, etc.  
         [0038]     Referring initially to  FIG. 1 , a preferred embodiment  10  of the subject invention is shown deployed within a tire  12 . The tire  12  is formed from conventional materials such as rubber or rubber composites by conventional means and may comprise a radial ply or bias ply configuration. A typical tire  12  is configured having a tread  14 , a shoulder  16 , an annular sidewall  18 , and a terminal bead  20 . An inner liner  22  is formed and defines a tire cavity  24 . The tire  12  is intended for mounted location upon an annular rim  26  having a peripheral rim flange and an outer rim flange surface  30 . Rim  26  is conventionally configured and composed of a suitably strong metal such as steel.  
         [0039]     An annular antenna  32  is provided and, in the preferred embodiment, embodies a sinusoidal configuration. Antenna  32  may be alternatively configured into alternative patterns or comprise a straight wire(s) if desired and may be filament wire, or cord or stranded wire. Acceptable materials for the wire include steel, aluminum, copper or other electrically conducting wire. As mentioned previously, the wire diameter is not generally considered critical for operation as an antenna and multiple strands of fine wire is preferred. The curvilinear form of antenna  32  provides flexibility and minimizes the risk of breakage during manufacture and use explained below.  
         [0040]     With continued reference to  FIG. 1 , a transponder module  34  of the general type described above is provided and may include means for sensing tire parameters such as pressure and temperature. Shown is an optional carrier strip of material  36  formed into the annular configuration shown. Carrier strip  36  is formed of electrically insulating, preferably semi-rigid elastomeric material common to industry such as rubber or plastic. The strip  36  is formed to substantially encapsulate the antenna wire(s)  32  and at least a portion of the transponder module  34  in the manner described below. In the post manufacturing state, therefore, the apparatus  10  comprises an annular bare wire antenna  32 , transponder module  34  in a unitary, generally circular, semi-rigid assembly that is readily transportable and handled for attachment to tire  12 . The diameter of the apparatus assembly  10  is a function of the size of the tire  12  and the preferred attachment location thereon.  
         [0041]      FIG. 2  illustrates a preferred location for annular apparatus  10  on a tire in accordance with the present invention. The tire  12  is mounted to a rim  26  in conventional fashion. The bead  20  of tire  12  is disposed within the rim  26  against flange  28 . Upper surface  30  of the flange  28  is located above a lower edge of the tire bead  20 . As will be appreciated, the flange  28  shields the lower portion of the tire  12  comprising bead  20  and defines an “RF INTERFERENCE” region  38  of the tire. A region  40  of tire  12  above region  38  at the sidewall  18  is further defined as a “HIGH STRAIN AMPLITUDE” region. As sidewall  18  flexes during operation of the tire on a vehicle, region  40  experiences a high level of strain. The region  42  located at the tread portion of the tire is referred to herein for explanatory purposes as a “COMPRESSIVE STRAIN” region. It is at region  42  that the tire  12  experiences a high level of compressive strain as the tire is operatively utilized.  
         [0042]     In combined reference to  FIGS. 1 and 2 , the apparatus  10  is affixed to liner  22  of the tire  12  either during manufacture of the tire or, as preferable, in a post-manufacture assembly operation. Attachment may be by means of an adhesive or the apparatus may be embedded into the tire itself during manufacture. Adhesives commonly utilized in the industry for tire patch and repair may be employed. The location on the tire to which apparatus  10  is attached pursuant to the instant invention is region  44  in  FIG. 2 , located between the RF INTERFERENCE region  38  and the HIGH STRAIN AMPLITUDE region  40 . It will be appreciated that region  38  would be equitable from a mechanical perspective since tire region  38  is relatively rigid, protected by rim flange  28 , and, experiences a relatively low strain level during operation of the tire. From an electrical perspective, however, region  38  of the tire  12 , shielded by rim flange  28 , is ill suited as a location for the transponder  34 .  
         [0043]     Location of the apparatus  10  within region  40  of the tire sidewall  18  is an option. Such a location would avoid the RF Interference caused by the rim. However, the tire sidewall  18  experiences high levels of strain during operation of the tire. Consequent damage to or breakage of components affixed to the sidewall may occur. Similarly, location of the apparatus  10  at the tread region  42  of tire  12  would avoid RF Interference from the rim but the tread region experiences high compression strain during operation of the tire. Location of tire monitoring system devices in such a location would be therefore be undesirable from a mechanical perspective.  
         [0044]     Consequently, apparatus  10  is preferably located pursuant to the invention within region  44  of the tire  12 . Region  44  is generally an annular region located substantially between  10  to  30  millimeters above the upper surface  30  of the rim flange  28  when tire  12  is mounted to rim  26 . Within region  44 , the apparatus is free from RF Interference from the flange  28  of rim  26 . Region  44  is further a relatively low strain amplitude region of the tire  12 . Thus, region  44  of the tire  12  represents an optimal location for apparatus  10  that balances the need for minimal RF Interference from the rim while mechanically protecting the apparatus  10  from damage due to strain forces introduced into the tire during its operation.  
         [0045]      FIG. 3  illustrates in enlarged fashion the subject apparatus  10  positioned against the tire  12 . The location of the antenna  32 , again, is within region  44  described as optimal in the preceding paragraph; that is, approximately  10 - 30  millimeters above the rim flange surface  30  when tire  12  is mounted to rim  26 . Attaching the apparatus  10  into tire  12  during its manufacture is possible pursuant to the invention but is not preferred since such a procedure would necessarily expose the transponder  34  and antenna to potentially damaging forces as the tire is formed. Consequently, it is preferable to attach the apparatus  10  to the tire  12  in a post manufacture process by adhesives or the like. The advantages of post manufacture assembly is that the apparatus  10  is spared the stress of the tire manufacturing process and the apparatus  10  may readily be removed and replaced in the event of breakage. Moreover, the unitary apparatus  10  shown in  FIG. 1  may readily be retrofitted by adhesive to pre-manufactured or used tires. Finally, the annular apparatus is a unitary assembly and may be conveniently inventoried in a range of diametric sizes so as to fit various sized pre-manufactured tires.  
         [0046]      FIG. 4  shows the transponder  34  located at its preferred location on a tire  14  and exposed to the tire cavity  24 . The transponder may include pressure and temperature sensors for monitoring the status of the cavity  24  and communicate such information to a remote transceiver  48  mounted to the vehicle frame  46 . The transceiver  48  is positioned opposite the antenna of the apparatus  10  and is in continuous communication therewith throughout the 360 degrees rotation of the tire  14 . Transceiver  48  is of a type commercially available in the industry and is electrically connected by lead  50  to conventional logic, processing and display electronics of the vehicle (not shown). As described previously, the position of the transponder module  34  is above the rim flange  28  so that RF communication between the transponder and the transceiver  48  is not impaired.  
         [0047]     With collective reference to  FIGS. 5-12 , the configuration of the annular apparatus  10  will be explained in greater detail. The transponder module generally comprises a base housing  52  formed of rubber or plastic material by conventional means. The housing  52  includes opposite sidewalls  54 ,  56  joining along a radiused bottom surface  55  to opposite vertical end walls  58 ,  60 . The walls  54 ,  55 ,  56 ,  58 , and  60  define a central compartment  62 . A through bore  64  extends through lower portion of the end walls  58 ,  60  in communication with the compartment  62 .  
         [0048]     The housing  52  further includes a cap member  68  likewise formed of conventional rubber or plastic material by conventional means such as injection molding. The cap member  68  includes an upper protrusion or “snout”  70  comprising vertical sidewalls  72  terminating at a horizontal upper surface  74 . A sensor port or aperture  76  is positioned at the middle of surface  74  and extends therethrough. A flange  78  peripherally defines a lower boundary of cap  68  and provides a horizontal ledge surface  80  that merges at a right angle with the vertical sidewalls  72 . The flange  78  is dimensioned to rest upon the upper end of the module base housing  52  as will be appreciated. The horizontal ledge surface  80  of cap  68  is disposed between the flange  78  and the vertical sidewalls  72 . Upper sidewall portions  81  are provided that taper inwardly toward upper surface  74 . The tapered profile of the cap  68  facilitates convenient and reliable manufacture of the apparatus  10 .  
         [0049]     In the illustrated embodiment, the transponder module  34  further includes a toroidal body (toroid)  82  composed of a material, such as a ferrite, having a high electromagnetic permeability. The body  82  generally comprises a cylinder having an elliptical cross-sectional configuration. The elliptical sectional configuration of body  82  serves to reduce its vertical dimension and allows for a more compact packaging of the body  82  within a transponder module. The body  82  includes a winding  84 , as shown, terminated to conductor leads  86 . A central through bore  88  projects through the body  82  in an axial or longitudinal direction.  
         [0050]     A protective sleeve member  90  is further provided sized for receipt and residence with the bore  88  of body  82 . The sleeve  90  comprises generally an elongate cylinder having an elliptical cross-section. The sleeve  90  further includes a circumferential sidewall  92  and an axial or longitudinal through bore  94 . Bore  94  is offset relative to the longitudinal axis of the sleeve  90  so as to create a wall  95  of increased thickness at an outward side of the sleeve  90 . An outwardly open longitudinal channel  96  is formed within the wall  95  as shown. The sleeve  90  is closely received within bore  88  of body  82  and winding  84  is received within the channel  96  of sleeve  90 .  
         [0051]     With continued reference to  FIGS. 5-12 , a circuit board  98  mounts within the central compartment  62  of the transponder base housing  52 . Circuit board  98  is typically configured to comprise an electronic package  100  mounted to an upper surface  102  and may include an electronic package  106  mounted to an underside  104 . The electronic packages  100 ,  106  are generically depicted in  FIGS. 5-12  and include the transponder sensors, logic, and RF transmitting systems necessary to perform tire cavity monitoring activity. The subject invention is not transponder design specific and any one of multiple conventional transponder systems may be utilized and mounted to one or both surfaces  100 ,  104  of circuit board  98 . The board  98  further includes lead receiving channels  108  fabricated within a board side.  
         [0052]     Assembly of the transponder module proceeds generally as follows. The sleeve  90  is inserted within the through bore  88  of the toroidal body  82  which is then inserted into the chamber  62  of the housing base  52 . Situated within chamber  62 , the through bore  94  of sleeve  90  and the bore  99  of body  82  co-axially align with housing through bore  64 . The winding  84  of body  82  is received within channel  96  of the sleeve  90  and leads  86  are routed upward. The number of turns in winding  84  is designed to impedance match the transponder electronics in a conventional manner. The board  98  mounts horizontally in the preferred embodiment within the housing  52  above the sleeve  90  and the toroidal body  82  through passage. Leads  86  from the winding  84  are routed into the channels  108  and electrically connected to the electronics  100 ,  106  on circuit board  98 . The peripheral flange  78  of the cap member  68  is thereafter positioned upon the upper surface  66  of the housing  52  and the interface is sealed by application of a suitable adhesive.  
         [0053]     In the assembled condition, the transponder module  34  is as shown in  FIG. 6 . The transponder module housing, internal assembly, and component orientation may be varied if desired in the practice of the invention. The transponder module  34  thus comprises a sealed self contained unit that includes circuit board and transponder electronics for monitoring parameters of a tire cavity such as pressure and temperature. The electronics of the transponder module  34  may further include tire identification information. The toroidal body  82  is electro-magnetically and mechanically coupled to the transponder package  24  via winding  84 . Alternatively, the body  82  may be eliminated and the antenna  32  electrically coupled directly to the transponder. The resultant annular assembly would likewise be positioned in the optimum location described above in a tire. A further alternative would be to couple the antenna  32  to the transponder through a transformer of conventional configuration having primary and secondary windings.  
         [0054]     The antenna  32  is routed through the transponder module  34  as seen best from  FIG. 5  and comprises a continuous loop. The antenna  32  in the preferred embodiment is formed into a sinusoidal configuration, the sinusoidal shape serving to provide antenna elongation capacity with which to counter strain forces in the tire from its operation. The antenna  32  projects through bore  94  of sleeve  90 , the bore  88  of body  82 , and the through bore  64  of housing  52  in non-contacting manner. The antenna  32  is thus mechanically decoupled from the transponder module  34 . It will be noted that the toroidal body  82  functions as a transformer in which the primary winding is eliminated. The antenna loop  32  is passed directly through the through bore  88  of the toroid  82  and couples magnetically with the body absent a primary winding. Electrical coupling occurs between the loop  32  and the toroidal body  82 , and therefore into the winding  84  because the current induced in the loop antenna  32  from the transceiver  48  magnetic field creates a magnetic near the loop. The magnetic field is induced directly into the toroidal body  82  that closely surrounds the antenna loop wire(s)  32 .  
         [0055]     Such a coupling, designated herein as Direct Magnetic Coupling (DMC), affords several distinct advantages. The DMC approach allows the antenna loop to pass through the transponder package without a mechanical connection and therefore eliminates the problems with making and maintaining a connection between the loop wire and the transponder package discussed previously. The winding  84  turn ratio may be varied to accommodate optimum impedance matching. Secondly, the DMC technique provides a high energy coupling. Furthermore, the process of attaching the antenna loop to a transponder is simplified rendering the remote coupling between wire bundles or cables and transponders substantially less difficult. Moreover, the magnetic coupling between annular antenna and transponder using the DMC technique is maintained in a continuous 360 degree read and dead zones in the interrogation area are avoided.  
         [0056]     As discussed previously, the assembly of  FIG. 5  may be embedded into a tire during its manufacture, although it is not preferable to do so. Incorporation of the annular apparatus during tire build imposes substantial strain into the tire monitoring components and may result in component breakage. In a post cure state, removal of an annular assembly or any component therein may be difficult or impossible. Consequently, it is preferred that the subject annular assembly be affixed to a tire as a post tire build operation.  
         [0057]     To do so, the antenna  32  and transponder  34  are first made into an independent assembly. An annular assembly results that is unitary and readily transported, stored, and handled. Creation of a unitary combination of antenna and transponder facilitates ease of incorporation of the annular assembly into a tire in a post build procedure. The assembly is positioned against the tire liner  22  at a location within the optimum region  44  discussed previously. The antenna  32  is at least partially embedded within a commonly available adhesive and affixed against the tire liner. Should the antenna transponder module break in transit or malfunction, the assembly  10  may be removed and replaced without damaging the tire. Moreover, the encapsulant material further serves to maintain the antenna and the toroidal body in their intended mutual orientation.  
         [0058]     Referring to  FIGS. 13-15  inclusive, the method of assembling the subject annular apparatus will be understood from the following. As will be appreciated the annular antenna ring is made separately and can be installed in a vulcanized tire at a tire plant, a warehouse, a tire mounting facility, or other appropriate location. The invention contemplates selecting an appropriate antenna comprising a bare wire or wires (step  154  of  FIG. 15 ). The wire antenna material is delivered to an assembly area where it is payed off and cut to the appropriate length (step  158 ), typically but not necessarily sixty inches for a sixteen inch tire. This becomes the antenna portion  32  of the ring. The wire may be of any number of various wire constructions or a composite of wire and other material. For example, the wire may be a twisted pair with textile or rubber filaments.  
         [0059]     A first end  138  of the cut antenna wire is passed through the ferrite hole in the transponder  34 . Alternative means of connecting the wire to the transponder may be used if preferred to establish the requisite magnetic coupling. Both ends  138 ,  140  of the cut antenna wire are then joined to provide a mechanical and electrical joint. This joint may be welded, crimped, or joined in some other way that meets the strength and electrical continuity requirements of the system. The resultant assembly comprises a 360 degree ring. Alternative means for assembling an annular antenna and transponder may be used, resulting in an annular transponder assembly.  
         [0060]      FIG. 15  illustrates the subject inventive method in block diagram form. Beginning at starting block  153 , the annular transponder is formed by any preferred means (step  156 ). A tire is measured in order to determine the location and magnitude of an effective region of tire imbalance (step  158 ). Pursuant to an aspect of the invention, a visual or other indicia may be used to mark a target region on the tire surface opposite the effective region of imbalance. The annular antenna ring and transponder assembly is then positioned against a surface location on the tire (step  160 ) so that the transponder acts as a counterbalance to the effective region of tire imbalance. For example, if a heavy imbalance in the tire is at zero degrees in the radial direction, then the transponder would be placed at 180 degrees in the radial direction. The transponder thus serves as a counter weight and offsets rather than reinforces the inherent imbalance of the tire. The annular transponder assembly is then affixed to the tire (step  162 ) by any appropriate means such as by adhesive, thus completing the assembly (step  164 ).  
         [0061]     While the above sets forth a preferred embodiment and alternative embodiments of the subject invention, the invention is not intended to be so limited. Other embodiments that will be apparent to those skilled in the art and which utilize the teachings herein set forth, are intended to be within the scope and spirit of the present invention.