Patent Publication Number: US-2010123010-A1

Title: Assembling structure of radio ic tag

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Japanese Patent Application No. 2008-296407 filed on Nov. 20, 2008, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a radio IC tag which transmits and receives information wirelessly, and, more specifically, to an assembling structure of the radio IC tag concerning a configuration of an antenna for transmitting and receiving information. 
     2. Description of the Related Art 
     Radio IC tags capable of reading and writing information have been widely used for information management or distribution management of various goods in recent years. 
     Such a radio IC tag is configured to include a small IC chip having a memory for recording information, and a small antenna for wirelessly transmitting the information recorded in the memory and receiving transmitted power or information. 
     The radio IC tag is equipped with, for example, a tiny IC chip about 0.4 mm in length and width and about 0.1 mm in thickness near the center of the long antenna and can be used by being attached to an article, an animal, or the like. If a user holds a reader/writer over the radio IC tag, information recorded in an IC chip equipped therein is read, thus enabling management of each article, animal, or the like. 
       FIG. 16A  and  FIG. 16B  are perspective views each illustrating a configuration of an assembly in which a radio IC tag  100  and a hologram H are attached to a product  109  using a dipole antenna according to the prior art. 
     The radio IC tag  100  according to the prior art typically has a dipole antenna (see  FIG. 16A ). 
     The radio IC tag  100  shown in  FIG. 16A  includes a dielectric body  101  as a base material, and a radiation conductor (antenna)  102  having a length of λ/2 (one half wavelength) in a longitudinal direction of a surface of the dielectric body  101 . The radiation conductor  102  is quipped with an IC chip  103  having a memory for recording information, in the substantial center thereof. 
     An L-shaped slit  102   s  for performing impedance matching is formed at the center of the radiation conductor  102 . 
     One end of the  102   s  extends to one end edge of a long side to separate the long side in a shorter direction of the radiation conductor  102 . A connecting terminal (not shown) of the IC chip  103  is connected to the radiation conductor  102  across the slit  102   s.    
     The following is patent documents related to the present Application and is publicly known: Japanese Laid-Open Patent Application, Publication No. 2008-117165; Japanese Laid-Open Patent Application, Publication No. 2005-309811; Japanese Laid-Open Patent Application, Publication No. 2006-311372 (paragraphs 0021 to 0024, FIG. 4); and Japanese Laid-Open Patent Application, Publication No. 2006-25390 (paragraphs 0022 to 0026, FIG. 4). 
     A hologram attached onto an article has been recently used to discriminate the authentic from its copies and to prevent forgery. 
     To enhance effects of the forgery prevention, attachment of both a hologram and a radio IC tag onto an article has also been attempted. 
     For example, such a configuration is considered that a hologram is attached on an article, on which a radio IC tag is attached. 
     However, the configuration has a problem that designing is not excellent because the radio IC tag attached on the article exposes to outside, and a user easily recognizes the radio IC tag, which is not advantageous. 
     In light of the above problem, in  FIG. 16A , the radio IC tag  100  is placed on a product  109  and is then covered with a hologram H. However, this configuration has a problem that a large difference of an input and output impedance between the radiation conductor (antenna)  102  and the IC chip  103  arises. This makes it impossible to read information recorded in the radio IC tag  100 . That is, the radio IC tag does not function suitably. 
     Due to this, if a distance between the radiation conductor (antenna)  102  and the hologram H is made larger, the radio IC tag will function. However, a seal thickness of the radio IC tag  100  becomes too large to be suitable for practical use. 
     Thus, as shown in  FIG. 16B , another configuration is proposed in which a gap g is created in the hologram H, and an IC chip  103  and an L-shaped slit  102   s  for impedance matching are exposed from the gap g in the hologram H (see FIG. 4 of Japanese Laid-Open Patent Application, Publication No. 2006-25390). However, the configuration has a problem that visual effect and decorative appearance is not excellent because a user can easily recognize the IC chip  103  of the radio IC tag  100  and the L-shaped slit  102   s  through the gap g in the hologram H. 
     The present invention has been made in light of the above problems and in an attempt to provide an assembling structure of a radio IC tag in which the decorative appearance is improved, freedom of designing is increased, and redesigning is not necessary. 
     SUMMARY OF THE INVENTION 
     In an assembling structure of a radio IC tag, the radio IC tag includes an IC chip for recording information therein and a first antenna connected to the IC chip for wirelessly transmitting or receiving information. The first antenna has a first gap for performing impedance matching. A conductive second antenna having a second gap is arranged over the IC chip, the first gap, and the first antenna. 
     Note that the second gap includes a gap which divides the second antenna. 
     Other features and advantages of the present invention will become more apparent from the following detailed description of the invention, when taken in conjunction with the accompanying exemplary drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a top view illustrating a radio IC tag T arranged on a product P according to a first embodiment.  FIG. 1B  is a cross sectional view illustrating the radio IC tag T when cut along the line A-A in  FIG. 1A .  FIG. 1C  is a view in the direction of the arrow B in  FIG. 1B . 
         FIG. 2A  is a plan view illustrating a second antenna for indicating experimental conditions thereof according to the first embodiment.  FIG. 2B  is a graph showing a relation between a sum of a length L 1  of a second antenna first part  2   a  plus a length L 2  of a second antenna second part  2   b  (corresponding to the horizontal axis) and a communication distance at a radio wave frequency of 2.4 GHz (corresponding to the vertical axis) under the test conditions indicated in  FIG. 2A .  FIG. 2C  is a graph showing a relation between a position of the first antenna  1  relative to the second antenna  2  shifted from an end edge (Ant 1  position=0) of the second antenna  2  in the longitudinal direction thereof (corresponding to the horizontal axis) and the communication distance at the radio wave frequency of 2.4 GHz (corresponding to the vertical axis). 
         FIG. 3A  is a perspective view illustrating a base material of a hologram in a third method of forming a slot in the hologram according to the first embodiment.  FIG. 3B  is a view in the direction of the arrow F in  FIG. 3A .  FIG. 3C  is a view illustrating the hologram with a metal film formed on a slant face of the base material shown in  FIG. 3B . 
         FIG. 4A  is a top view illustrating an assembling structure of a radio IC tag according to another example of the first embodiment.  FIG. 4B  is a cross sectional view when cut along the line C-C in  FIG. 4A . 
         FIG. 5A  is a view in the direction of the arrow B in  FIG. 1B  according to a first variation of the first embodiment.  FIG. 5B  is a plan view illustrating a second antenna  22  of  FIG. 5A . 
         FIG. 6A  is a plan view illustrating a second antenna  22  of the still another example of the first variation according to the first embodiment.  FIG. 6B  is a view of  FIG. 1B  in the direction of the arrow B according to the still another example of the first variation of the first embodiment. 
         FIG. 7A  is a view in the direction of the arrow B in  FIG. 1B  according to a second variation of the first embodiment.  FIG. 7B  is a plan view illustrating a second antenna of  FIG. 7A . 
         FIG. 8A  is a view in the direction of the arrow B in  FIG. 1B  according to another example of the second variation of the first embodiment.  FIG. 8B  is a plan view illustrating a second antenna of  FIG. 8A . 
         FIG. 9A  is a view in the direction of the arrow B in  FIG. 1B  according to a second embodiment.  FIG. 9B  is a plan view illustrating a second antenna of  FIG. 9A . 
         FIG. 10  is a view in the direction of the arrow B in  FIG. 1B  according to a first variation of the second embodiment. 
         FIG. 11  is a view in the direction of the arrow B in  FIG. 1B  according to a second variation of the second embodiment. 
         FIG. 12A  is a view in the direction of the arrow B in  FIG. 1B  according to a third embodiment.  FIG. 12B  is a plan view illustrating a second antenna of  FIG. 12A . 
         FIG. 13A  is a view in the direction of the arrow B in  FIG. 1B  according to a first variation of the third embodiment.  FIG. 13B  is a plan view illustrating a second antenna of  FIG. 13A . 
         FIG. 14A  is a perspective view illustrating an IC chip medium with a radio IC tag  9 T embedded therein according to a fourth embodiment.  FIG. 14B  is a cross sectional view when cut along the line D-D in  FIG. 14A . 
         FIG. 15A  is a perspective view illustrating another IC chip medium with the radio IC tag shown in  FIG. 14A  embedded therein and with a hologram as a second antenna disposed vertically facing the IC chip medium.  FIG. 15B  is a cross sectional view when cut along the line E-E in  FIG. 15A . 
         FIG. 16A  and  FIG. 16B  are perspective views each illustrating an assembly in which a radio IC tag using a dipole antenna and a hologram are attached to a product according to the prior art. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT 
     Embodiments of the present invention are described next in detail with reference to the related drawings. 
     First Embodiment 
       FIG. 1A  is a top view illustrating a radio IC tag T according to a first embodiment of the present invention. In  FIG. 1A , the radio IC tag T is arranged on a product P (indicated with dashed lines in  FIG. 1B ).  FIG. 1B  is a cross-sectional view when cut along the line A-A in  FIG. 1A .  FIG. 1C  is a view in the direction of the arrow B in  FIG. 1B . 
     &lt;Outline of Radio IC Tag T&gt; 
     The radio IC tag T according to the first embodiment is attached to a product P so as to discriminate the authentic from copies of the product P by reading information recorded in the radio IC tag T using a reader/writer (not shown). 
     The radio IC tag T illustrated in  FIGS. 1A to 1C  is equipped with an IC chip  3  on a side nearer to the product P, rather than to a hologram H (see  FIG. 1B ). 
     That is, the hologram H (which may collectively represent a hologram first part H 1  and a hologram second part H 2 , and which may also be referred to as a second antenna to be described later) for enhancing decorative appearance and forgery preventive property of the product P thereon (shown on an upper side of  FIG. 1B ) is mounted on the radio IC tag T attached to the product P. In other words, a user actually sees the hologram H when the user sees the product P because it is the hologram H that is positioned at an outermost of the product P. 
     In  FIG. 1A , a metal evaporated film of the hologram H (H 1 , H 2 ) is positioned on the side nearest to the user (an upper side with respect to the plane of  FIG. 1A ). The user recognizes the metal evaporated film as hologram patterns. 
     The metal evaporated film of the hologram H (H 1 , H 2 ) is electrically conductive and operates as a second antenna  2  of the radio IC tag T to be described later. 
     The assembling structure of the radio IC tag T includes an arrangement of the hologram first and second parts H 1 , H 2  (which operate as second antennas  2   a ,  2   b , which may be collectively referred to as a second antenna  2 ) above a first antenna  1  for transmitting and receiving information recorded in the radio IC tag T, and an arrangement of the IC chip  3  of the radio IC tag T and a L-shaped slit  1   s  (as an impedance matching circuit) of the first antenna  1  without being placed vertically above a slot  2   s  between the holograms H 1  ( 2   a ) and H 2  ( 2   b ). 
     The assembling structure ensures a reliable read of information recorded in the radio IC tag T read by a reader/writer. Further, the assembling structure allows to improve ornamental design of the hologram H without damaging its decorative appearance because the IC chip  3  and the L-shaped slit  1   s  of the first antenna  1  do not expose from the slot  2   s  between the holograms H 1 , H 2 . 
     &lt;Radio IC Tag T&gt; 
     The radio IC tag T includes: the IC chip  3  for recording information to be read by a reader/writer; the first antenna  1  with the IC chip  3  connected to a substantially central portion thereof via an electrode; and an insulating base material  4  with the first antenna  1  having the IC chip  3  equipped therewith. 
     The first antenna  1  is a dipole antenna and has the L-shaped slit  1   s  for impedance matching at the central portion thereof. 
     One end of the L-shaped slit  1   s  extends to one of the two end edges in a longitudinal direction of the first antenna  1  to separate one end edge in the longitudinal direction of the first antenna  1 . Two electrodes (not shown) of the IC chip  3  are connected to the first antenna  1  across the one end of the L-shaped slit  1   s.    
     The L-shaped slit  1   s  not limited to be L-shaped and may be T-shaped as far as such a slit can perform impedance matching. 
     The IC chip  3  of the radio IC tag T includes, for example: a limiter circuit for protecting the IC chip  3  from input voltage from the first antenna  1 ; a rectifier circuit for converting alternating current inputted to the first antenna  1  into direct current; a demodulating circuit for demodulating a command or a data transmitted from a reader/writer (not shown) into a signal sequence constituted of “1” and “0”; a modulation circuit for modulating a carrier wave with a data transmitted to the reader/writer; a control circuit for controlling transmission and receipt of information, read and write in an internal memory, or the like; and a memory for recording information. 
     The first antenna  1  of the radio IC tag T is formed by, for example, etching copper or aluminum on the base material  4  made of a PET (Polyethylene Terephthalate) film or the like, or printing a conductive paste such as silver. 
     With the configuration described above, information stored in the radio IC tag T is wirelessly read or recorded in the memory of the radio IC tag T, using a reader/writer (not shown) via the first antenna  1 . 
     &lt;Second Antenna  2  ( 2   a ,  2   b )&gt; 
     As shown in  FIGS. 1A to 1C , the hologram H (H 1 , H 2 ) is arranged adjacent to the base material  4  of the radio IC tag T attached to the product P. 
     The hologram H is divided into the hologram first part H 1  and the hologram second part H 2  across the slot  2   s  which is a gap therebetween. The gap opens on both ends in a shorter direction of the hologram H (in the up and down directions with respect to the plane of  FIG. 1A ). 
     A width dimension  2   s   1  of the slot  2   s  is 100 μm. It is electrically desirable from a viewpoint of a function of an antenna that the dimension  2   s   1  of the slot  2   s  is larger. However, the dimension  2   s   1  as large as 100 μm is sufficient at minimum. Note that the slot  2   s  of the second antenna  2  is different from the L-shaped slit  1   s  of the first antenna  1  in that the slot  2   s  is a path of electric or magnetic field while the L-shaped slit  1   s  performs impedance matching. 
     The holograms H 1 , H 2  (second antenna  2 ) are arranged vertically over the first antenna  1  (see  FIG. 1A  and  FIG. 1B ). The slot  2   s  between the hologram first and second parts H 1 , H 2  is arranged in a position not vertically over the IC chip  3  and the L-shaped slit  1   s  of the first antenna  1 . 
     The hologram H is created by, for example, forming irregularities such as embossings and lines on one surface of a base material made of PET or the like and forming a metal evaporated film on the irregularities. This realizes decorative appearance and forgery preventive property which is produced by effects of light interference. Note that the size of the irregularities on the base material are approximately 0.5 to 2 μm so as to obtain the effects of light interference. 
     The metal evaporated film is a good conductor of the hologram H, is made of, for example, aluminum (Al), gold (Au), copper (Cu), or the like, and constitutes the second antenna  2  (which may collectively represent a second antenna first part  2   a  and a second antenna second part  2   b  to be described in detail hereinafter) of the radio IC tag T. 
     More specifically, the metal evaporated film of the hologram H 1  constitutes the second antenna first part  2   a , and the metal evaporated film of the hologram H 2  constitutes the second antenna second part  2   b.    
     Note that the second antenna  2  is not limited to the metal evaporated film of the hologram H 1  but may be any conductor as long as having conductivity. 
     &lt;Operations of Second Antenna  2  ( 2   a ,  2   b )&gt; 
       FIGS. 2A to 2C  are views illustrating operations of the second antenna  2  ( 2   a ,  2   b ).  FIG. 2A  is a plan view illustrating the second antenna  2  ( 2   a ,  2   b ) for indicating experimental conditions of the second antenna  2  ( 2   a ,  2   b ).  FIG. 2B  is a graph showing a relation between a sum of a length L 1  of the second antenna first part  2   a  plus a length L 2  of the second antenna second part  2   b  (corresponding to the horizontal axis) and a communication distance at a radio wave frequency of 2.4 GHz (corresponding to the vertical axis) under the test conditions indicated in  FIG. 2A .  FIG. 2C  is a graph showing a relation between a position of the first antenna  1  relative to the second antenna  2  shifted from an end edge (Ant 1  position=0) of the second antenna  2  in the longitudinal direction thereof (corresponding to the horizontal axis) and the communication distance at the radio wave frequency of 2.4 GHz (corresponding to the vertical axis). 
     In the tests of the record antenna  2  represented in  FIG. 2B  and  FIG. 2C , “L 1 +L 2 ” was taken as a long side (the longitudinal direction) of the second antenna  2 ; a length W of a short side thereof was 40 mm; and a width  2   s   1  of the slot  2   s  was 0.5 mm. 
     As shown in  FIG. 2B , the longest communication distance was obtained when “L 1 +L 2 ” had a measurement of ½ of the wavelength λ at a radio wave frequency of 2.4 GHz. 
     That is, the second antenna  2  obtains the largest gain at λ/2. It is thus estimated that the second antenna  2  functions as a dipole antenna and is electrically connected to the first antenna  1  with capacitive coupling. In other words, it is estimated that an electric field in the second antenna  2  is transmitted to the first antenna  1  with capacitive coupling. The function is hereinafter referred to as a dipole mode. 
       FIG. 2C  shows communication distances (corresponding to the vertical axis) of the second antenna  2  according to different positions at which the first antenna  1  is attached. The positions are: a portion just beside an end of the long side of the second antenna  2  (an edge in the longitudinal direction thereof), which may also be referred to as “Ant 1  position=0 (mm)”; the middle in the longitudinal direction of the second antenna  2 , which may also be referred to as “Ant 1  position=20 (mm)”; and a portion just beside the other end of the long side of the second antenna  2  (the other edge in the longitudinal direction thereof), which may also be referred to as “Ant 1  position=40 (mm). In the tests, similarly to FIG. B, “L 1 +L 2 ” was taken as the long side (the longitudinal direction) of the second antenna  2 ; the length W of the short side thereof was 40 mm; and the width  2   s   1  of the slot  2   s  was 0.5 mm. 
     A so-called slot antenna which has a long rectangular opening (that is, a slot with both ends thereof closed) at the center of a metal sheet (a measurement in the longitudinal direction=λ/2) has different impedance at its feeding point, according to different feeding positions in the longitudinal direction of the opening. The impedance is higher at a central portion and is lower at a portion close to the both ends in the longitudinal direction of the opening. 
     This means that if impedance at a feeding position of an antenna matches impedance at a feeder (for example, an IC chip), feeding efficiency to the antenna is increased, thus allowing efficient radio-wave emission. This results in an extension of the communication distance. 
       FIG. 2C  demonstrates that the communication distance (the vertical axis) varies according to the positions at which the first antenna  1  is attached (the horizontal axis). 
     The communication distance (the vertical axis) varies symmetrical with respect to the positions at which the first antenna  1  is attached. Such a characteristic of the second antenna  2  appears to be similar to a slot antenna. 
     Nonetheless, the second antenna  2  is different from the slot antenna in that the both ends of the slot  2   s  thereof are opened. At present, it is an estimation that the second antenna  2  is similar to a slot antenna. Such a function is, however, referred to as a slot mode hereinafter. 
     &lt;Technique of Creating Slot  2   s  of Second Antenna  2 &gt; 
     Next are described techniques of creating the slot  2   s  of the second antenna  2 . 
     A first technique is, for example, as follows. A metal film made of Al, Au, Cu, or the like is evaporated onto a base material made of PET or the like to prepare the hologram H. At this time, a portion to be made into the slot  2   s  is masked so as not to be evaporated with the metal film thereon. That is, when a metal evaporated film as a light reflection layer is formed on a base material constituting the hologram H, a portion (on which a metal film is not formed) constituting the slot  2   s  is masked, thus creating the slot  2   s.    
     The first technique utilizes a so-called mask method in which a portion to be made into a slot is masked when a metal film of the first hologram H is formed. 
     A second technique is as follows. A metal film is formed on a whole surface of a base material constituting the hologram H. Part of the metal film to be formed into the slot  2   s  is removed with resist mask. 
     A third technique is shown in  FIGS. 3A to 3C .  FIG. 3A  is a perspective view illustrating a base material h 1  of the hologram H.  FIG. 3B  is a view in the direction of the arrow F in  FIG. 3A .  FIG. 3C  is a view illustrating the hologram H with a metal film k 1  formed on slant faces h 2  of the base material h 1  shown in  FIG. 3B . 
     The third method is as follows. A plurality of slant faces h 2  are formed on a surface of the base material h 1  constituting the hologram H as shown in  FIG. 3A . 
     The base material h 1  having a plurality of slant faces h 2  is herein made of two roll materials. One roll has a smooth cylindrical surface, and the other has a cylindrical surface with a plurality of slant faces h 2 . 
     The two rolls are used to prepare the base material h 1  of the hologram H with a plurality of slant faces h 2  formed thereon. A thickness s 1  of the base material h 1  is, for example, 100 μm. 
     In  FIG. 3B , metal such as Al, Au, and Sn is deposited onto the base material h 1  having a plurality of slant faces h 2  from an oblique direction as shown with arrows α 1 , using anisotropic deposition such as a sputtering method. In  FIG. 3C , the hologram H with the metal film k 1  formed on the slant faces h 2  of the base material h 1  is produced. 
     A thickness s 2  of a light reflection layer (the metal film k 1 ) of the hologram H is 50 to 100 nm and is designed to be in a range between about 10 to about 1000 nm. 
     As described above, the metal is deposited onto the hologram H from the oblique direction without forming the metal film k 1  on vertical portions (metal film non-formation portions h 3 ) of the base material h 1 . This is advantageous because the slant face h 2  is electrically separated from the metal film k 1 , thus allowing an electric field to pass through the metal film non-formation portions h 3 . 
     Thus, if the hologram H having the metal film k 1  on the slant faces h 2  of the base material h 1  is applied to a read of information in the radio IC tag T shown in  FIG. 1 , radio waves from a reader/writer (not shown) can travel along the metal film k 1  on the slant faces h 2  of the hologram H as shown with arrows α 21  of  FIG. 3C , pass through the metal film non-formation portions h 3  as shown with arrows α 23 , and further travel toward the first antenna  1  of the radio IC tag T. 
     In any assembling structures of the radio IC tag T and the second antenna  2 , a base material for holding the second antenna  2  is required. 
     For example, as shown in  FIG. 3C , if the second antenna  2  is a reflection layer of the hologram H, the base material h 1  (see  FIG. 3A ) of a hologram seal body of the hologram H is the base material. Irregularities which scatter light are formed on a surface as the second antenna  2  (the metal film k 1  in  FIG. 3C ) of the base material h 1 , which makes the surface function as a hologram seal. 
     &lt;Another Example of Assembling Structure of Radio IC Tag T and Second Antenna  2 &gt; 
     Next is described another example of an assembling structure of the radio IC tag T and the second antenna  2  with reference to  FIG. 4 . 
       FIGS. 4A and 4B  are views each illustrating the radio IC tag T and the second antenna  2  attached onto the product P according to another example of the first embodiment.  FIG. 4A  is a top view illustrating an assembling structure of the radio IC tag  2  according to another example of the first embodiment.  FIG. 4B  is a cross sectional view when cut along the line C-C in  FIG. 4A . 
     The assembling structure of the radio IC tag  2  according to another example of the first embodiment is embodied by assembling the radio IC tag T equipped with the IC chip  3  on the first antenna  1  on the insulating base material  4 , to the product P via an adhesive material  5 , such that a surface with the IC chip  3  of the radio IC tag T is positioned nearer to the product P, rather than therein the second antenna  2 . 
       FIG. 4A  and  FIG. 4B  show an assembly in which the second antenna  2  divided into the second antenna first part  2   a  and the second antenna second part  2   b  by the slot  2   s  is mounted on a base material  6  made of resin or the like. 
     The base material  6  on which the second antenna  2  is mounted is made of, for example, PET or PP (polypropylene) and is 10 to 100 μm thick. 
     A protective layer  7  (see  FIG. 4B ) protects the second antenna  2  and is an adhesive material or a resin film made of PET, PP, or the like for holding the second antenna  2 . 
     In the assembly, the second antenna  2  is placed over the first antenna  1  of the radio IC tag T attached onto the product P, via the protective layer  7 ; and the slot  2   s  of the second antenna  2  is prevented from being positioned vertically over the IC chip  3  and the L-shaped slit  1   s  of the first antenna  1 . 
     The first antenna  1  may be formed as follows. The second antenna  2  ( 2   a ,  2   b ) is formed on the base material  6 . The protective layer  7  as an insulating layer is formed on the second antenna  2 . The first antenna  1  is directly printed on the protective layer  7  using conductive paste such as silver. And, finally, the IC chip  3  is attached onto the first antenna  1 . 
     The printing is performed with appropriate adjustments such that the slot  2   s  of the second antenna  2  is not positioned vertically over the IC chip  3  and the L-shaped slit  1   s  of the first antenna  1 . 
     In any assembling structures of the radio IC tag T, a base material for holding the second antenna  2  is required. 
     For example, as shown in  FIGS. 4A and 4B , if the second antenna  2  is a flat metal seal, the base material  6  simply needs to have a function of holding the second antenna  2 . 
     &lt;Advantages&gt; 
     With configurations according to the first embodiment, the IC chip  3  of the radio IC tag T and the L-shaped slit  1   s  as an impedance matching circuit of the first antenna  1  are not exposed to outside. This results in improvement of designing an assembling structure of a radio IC tag with more flexibility in designing. 
     The IC chip  3  of the radio IC tag T is herein covered with the second antenna  2 , which can protect the IC chip  3 . 
     Further, the first antenna  1  and the second antenna  2  are operated in a state where the second antenna  2  is placed vertically over the first antenna  1 . This means that an existing type of the second antenna  2  can be used as it is without needs of redesigning or adjustments. 
     With the configuration shown in  FIG. 3C , if a user sees the hologram H, what the user recognizes is mainly a plurality of the slant faces h 2  of the hologram H (seen from above with respect to the plane of  FIG. 3C ). The user does not recognize the metal film non-formation portions h 3  so much. This prevents the slot  2   s  of the second antenna  2  from being clearly recognized and improves designing. 
     &lt;First Variation of First Embodiment&gt; 
     Next is described a first variation of the first embodiment with reference to  FIG. 5A  and  FIG. 5B . 
       FIG. 5A  is a view in the direction of the arrow B in  FIG. 1B  according to the first variation of the first embodiment.  FIG. 5B  is a plan view illustrating a second antenna  22  of  FIG. 5A . 
     As shown in  FIG. 5A , in the first variation, an area in which a first antenna  21  vertically faces the second antenna  22  is increased so as to increase an electrical junction area therebetween, thus extending a communication distance between a reader/writer (not shown) and a radio IC tag  2 T. 
     Except the above-mentioned, a configuration of the first variation is similar to that of the first embodiment, and its detailed description is omitted herefrom. 
     As shown in  FIG. 5B , the second antenna  22  of the first variation is divided into a second antenna first part  22   a  and a second antenna second part  22   b  via a slot  22   s , like the second antenna  2  ( 2   a ,  2   b ) of the first embodiment (see  FIG. 1A ). 
     The second antenna first part  22   a  of the first variation corresponds to the second antenna first part  2   a  of the first embodiment; the second antenna second part  22   b  of the first variation, the second antenna second part  2   b  of the first embodiment; and the slot  22   s  of the first variation, the slot of the first embodiment. 
     As shown in  FIG. 5A , a base material  24  of the radio IC tag  2 T is formed in a substantial L shape including a base material first part  24   a  facing the second antenna first part  22   a  and a base material second part  24   b  facing the second antenna first and second parts  22   a ,  22   b.    
     Similarly, the first antenna  21  mounted on the base material  24  is formed in a substantial L shape including a first antenna first part  21   a  mounted on the second antenna first part  22   a  and a first antenna second part  21   b  mounted on the second antenna first and second parts  22   a ,  22   b.    
     Herein, an IC chip  23  of the radio IC tag  2 T and an L-shaped slit  21   s  (an impedance matching circuit) of the first antenna  21  are arranged such that the IC chip  23  and the L-shaped slit  21   s  are not placed over the slot  22   s  between the second antenna first and second parts  22   a ,  22   b.    
     With the above configuration according the first variation, in addition to the advantages of the first embodiment, the area in which the first antenna  21  faces the second antenna  22 , that is, the electrical juncture area therebetween is increased. This enables an extension of the communication distance between the reader/writer (not shown) and the radio IC tag  2 T. 
       FIGS. 6A and 6B  are views each illustrating a still another example according to the first variation of the first embodiment, in which the slot  22   s  shown in  FIGS. 5A and 5B  is modified.  FIG. 6A  is a plan view illustrating a second antenna  22 ′ according to the still another example of the first variation of the first embodiment.  FIG. 6B  is a view in the direction of the arrow B in  FIG. 1B  according to the still another example of the first variation of the first embodiment. 
     As shown in  FIG. 6A , in the still another example of the first variation of the first embodiment, a slot  22   s   2 ′ is additionally formed in the second antenna  22 ′. That is, slots  22   s   1 ′ and  22   s   2 ′ are formed at both ends of the second antenna  22 ′. Preferably, but not necessarily, the slots  22   s   1 ′ and  22   s   2 ′ are formed symmetrically or substantially symmetrically. 
     With the above configuration, the second antenna  22 ′ is divided into a second antenna first area  22   a ′ and a second antenna second area  22   b ′ across the  22   s   1 ′ and is also divided into the second antenna second area  22   b ′ and a second antenna third area  22   c ′ across the  22   s   2 ′. 
     As shown in  FIG. 6B , the first antenna first area  21   a ′ of the first antenna  21 ′ is formed in a shorter direction of the second antenna  22 ′ (see  FIG. 7A ) and is arranged to face the second antenna first area  22   a ′. The first antenna second area  21   b ′ which is adjacent to the first antenna first area  21   a ′ is formed in a longitudinal direction of the second antenna  22 ′ (see  FIG. 7A ) and is arranged to face the second antenna first, second, and third areas  22   a ′,  22   b ′,  22   c ′. The first antenna third area  21   c ′ which is adjacent to the first antenna second area  21   b ′ is formed in the shorter direction of the second antenna  22 ′ (see  FIG. 7A ) and is arranged to face the second antenna third area  22   c′.    
     Herein, an IC chip  23 ′ of the radio IC tag  2 T′ and an L-shaped slit  21   s ′ (impedance matching circuit) of the first antenna  21 ′ are arranged such that the IC chip  23 ′ and the L-shaped slit  21   s ′ are not placed over the slots  22   s   1 ′,  22   s   2 ′ between the second antenna first, second, and third areas  22   a ′,  22   b ′,  22   c′.    
     With the above configuration of the still another example of the first variation, the slots  22   s   1 ′,  22   s   2 ′ are formed near the both ends of the second antenna  22 ′. This enables an increase in the length of the second antenna  22 . That is, the lengths in respective longitudinal directions of the second antenna first, second, third areas  22   a ′,  22   b ′,  22   c ′, are increased, thus extending the communication distance. 
     Further, the slots  22   s   1 ′,  22   s   2 ′ are formed symmetrically or substantially symmetrically positioned with respect the second antenna  22 ′. This prevents the slots  22   s   1 ′,  22   s   2 ′ from being clearly recognized and improves designing. 
     If a length of the second antenna  22 ′ is predetermined, a size of the second antenna  22 ′ with the configuration can be made smaller, thus expanding applicability. 
     For example, if the second antenna  22 ′ is made of a hologram seal, the hologram seal used can be made smaller, thus expanding applicability. 
     Moreover, the longer second antenna  22 ′ and the communication distance can make second antenna  22 ′ smaller, which allows an assembly with the configuration more compact. 
     The still another example of the first variation describes the configuration in which the second antenna  22 ′ is divided into the second antenna first, second, third areas  22   a ′,  22   b ′,  22   c ′. However, another configuration is also possible in which the second antenna first area  22   a ′ is partly joined to the second antenna second area  22   b ′, and/or the second antenna second area  22   b ′ is partly joined to the second antenna third area  22   c′.    
     &lt;Second Variation of First Embodiment&gt; 
     Next is described a second variation according to the first embodiment with reference to  FIGS. 7A ,  7 B,  8 A, and  8 B. 
       FIG. 7A  is a view in the direction of the arrow B in  FIG. 1B  according to the second variation of the first embodiment.  FIG. 7B  is a plan view illustrating a second antenna  32  of  FIG. 7A . 
     The second variation has a configuration in which the slot  2   s  of the second antenna  2  according to the first embodiment (see  FIG. 1 ) is changed to a plurality of slots  32   s   1 ,  32   s   2 ,  32   s   3 , and  32   s   4  so as to be less recognizable. 
     Except the above-mentioned, a configuration of the second variation is similar to that of the first embodiment, and its detailed description is omitted herefrom. 
     As shown in  FIG. 7B , in the second variation, a plurality of slots  32   s   1 ,  32   s   2 ,  32   s   3 , are formed in a second antenna first part  32   a . A slot  32   s   4  is further formed between the second antenna first part  32   a  and a second antenna second part  32   b.    
     That is, the second antenna first part  32   a  is divided into a second antenna first area  32   a   1 , a second antenna second area  32   a   2 , a second antenna third area  32   a   3 , and a second antenna fourth area  32   a   4 . 
     As shown in  FIG. 7A , a radio IC tag  3 T is disposed facing the second antenna first part  32   a  and the second antenna second part  32   b.    
     Larger widths s 3  of the slots  32   s   1 ,  32   s   2 ,  32   s   3 ,  32   s   4 , are electrically more advantageous, however, the widths s 3  of about 100 μm are sufficient. 
     With the above configuration of the second variation, the slots  32   s   1 ,  32   s   2 ,  32   s   3  are formed also in the second antenna first part  32   a . Thus, when a user sees the second antenna  32 , the increased number of the slots  32   s   1 ,  32   s   2 ,  32   s   3 , in a wider area reduces a contrast change in the second antenna  32 , compared to a single slot. This makes the slots  32   s   1 ,  32   s   2 ,  32   s   3 , less recognizable by the user and improves designing. 
       FIGS. 8A and 8B  each show another example of the second variation shown in  FIGS. 7A and 7B , in which positions of the slots  32   s   1 ,  32   s   2 ,  32   s   3  of  FIGS. 7A and 7B  are modified.  FIG. 8A  is a view in the direction of the arrow Bin  FIG. 1B  according to another example of the second variation of the first embodiment.  FIG. 8B  is a plan view illustrating a second antenna  32  of  FIG. 8A . 
     In another example of the second variation shown in  FIGS. 8A and 8B , the slots  32   s   1 ,  32   s   2 ,  32   s   3  are formed in the second antenna second part  32   b , instead of the second antenna first part  32   a.    
     Except the above-mentioned, a configuration of another example is similar to that of the second variation of the first embodiment, and its detailed description is omitted herefrom. 
     Note that, in the first embodiment described above, the product P made of resin demonstrates better communication performance of than the product P made of metal. It is estimated that this is because the slot  2   s  of the second antenna  2  is opened at both ends thereof, and the second antenna  2  is divided into two. 
     Second Embodiment 
     Next is described a second embodiment with reference to  FIGS. 9A and 9B . 
       FIG. 9A  is a view in the direction of the arrow B in  FIG. 1B  according to the second embodiment.  FIG. 7B  is a plan view illustrating a second antenna  42  of  FIG. 9A . 
     The second embodiment is configured to have the second antenna  42 , for example, in a substantial square shape when viewed from the top, because a hologram often used is in an elliptical shape. 
     Except the above-mentioned, a configuration of the second embodiment is similar to that of the first embodiment, and its detailed description is omitted herefrom. 
     As shown in  FIG. 9B , in the second embodiment, the second antenna  42  has a substantially square shape as a whole and is divided into a substantially L-shaped second antenna first part  42   a  and a substantially square-shaped second antenna second part  42   b  via a slot  42   s  extending in a substantial L shape. 
     The substantially L-shaped second antenna first part  42   a  includes a second antenna first part first area  42   a   1  and a second antenna first part second area  42   a   2 , combination of which forms an L shape. 
     As shown in  FIG. 9A , a radio IC tag  4 T is attached to the second antenna  42  such that: a first antenna  41  of the radio IC tag  4 T is placed on the second antenna  42 ; and an IC chip  43  of the radio IC tag  4 T and an L-shaped slit  41   s  of the first antenna  41  are positioned not over the substantially L-shaped slot  42   s  of the second antenna  42 . 
     That is, the IC chip  43  of the radio IC tag  4 T and the L-shaped slit  41   s  of the first antenna  41  are arranged vertically displacing the substantially L-shaped slot  42   s  and facing the second antenna  42 . 
     &lt;Advantages&gt; 
     With the configuration according to the second embodiment, an assembly having an assembling structure of the radio IC tag  4 T forms a substantial square, thus allowing a hologram which often has an elliptical shape to be used as a second antenna. 
     Further, with the configuration, the slot  42   s  has a substantial L shape and a length thereof in a longitudinal direction is well secured along the substantial L shape. If the second antenna  42  is being operated in the slot mode, a long communication distance of the radio IC tag  4 T can be realized because the slot  42   s  opens long. 
     Or, if the second antenna  42  is being operated in the dipole mode, the second antenna  42  becomes more efficient with a longer dipole antenna. This is because: the second antenna  42   a  has the substantial L shape; a length thereof in the longitudinal direction can be well obtained along the substantial L shape; and a sufficient length of the second antenna  42  as a whole can be secured. 
     In  FIGS. 9A and 9B , a configuration is described in which the second antenna  42  includes the substantially square-shaped second antenna second part  42   b  and the substantially L-shaped second antenna first part  42   a  surrounding the second antenna second part  42   b . However, the configuration is not limited to this. Any other configuration is possible as long as the second antenna first part  42   a  surrounds a portion of a circumference of the second antenna second part  42   b  via the slot  42   s  (which may also be referred to as a second gap). 
     &lt;First Variation of Second Embodiment&gt; 
     Next is described a first variation of the second embodiment with reference to  FIG. 10 . 
       FIG. 10  is a view in the direction of the arrow B in  FIG. 1B  according to the first variation of the second embodiment. 
     In the first variation of the second embodiment, an area in which a second antenna  52  faces a first antenna  51  of a radio IC tag  5 T is increased so as to increase an electrical junction area of the second antenna  52  and the first antenna  51 . 
     Except the above-mentioned, a configuration of the first variation is similar to that of the second embodiment, and its detailed description is omitted herefrom. 
     The second antenna  52  (including a second antenna first part  52   a  and a second antenna second part  52   b ) of the first variation of the second embodiment has a configuration same as the second antenna  42  of the second embodiment. 
     As shown in  FIG. 10 , a base material  54  of a radio IC tag  5 T has a substantial L shape and includes, via a slot  52   s , a base material first part  54   a  substantially facing the second antenna first part  52   a , and a base material second part  54   b  substantially facing the second antenna second part  52   b.    
     The first antenna  51  mounted on the base material  54  has a shape contouring the substantially L-shaped base material  54 . The first antenna  51  includes: an antenna first area  51   a  mounted on the base material first part  54   a ; and an antenna second area  51   b  mounted on the base material second part  54   b.    
     With the above configuration, the antenna first area  51   a  of the first antenna  51  can be disposed substantially facing the second antenna first part  52   a ; and the antenna second area  51   b  of the first antenna  51  can be disposed substantially facing the second antenna second part  52   b.    
     As described above, the first antenna  51  of the radio IC tag  5 T is placed over the second antenna  52 . Further, an IC chip  53  of the radio IC tag  5 T and an L-shaped slit  51   s  of the first antenna  51  are arranged not facing or being placed over the substantially L-shaped slot  52   s  of the second antenna  52 . 
     With the configuration of the first variation of the second embodiment, the area in which the second antenna  52  faces the first antenna  51  of the radio IC tag  5 T is increased, and the electrical juncture area therebetween is increased. That is, an electrical juncture therebetween is enhanced. This enables an extension of a communication distance of the radio IC tag  5 T. 
     &lt;Second Variation of Second Embodiment&gt; 
     Next is described a second variation of the second embodiment with reference to  FIG. 11 . 
       FIG. 11  is a view in the direction of the arrow B in  FIG. 1B  according to the second variation of the second embodiment. 
     The second variation of the second embodiment has a configuration in which shapes and arrangements of a first antenna  61  and a second antenna  62  make it possible for a reader/writer (not shown) equipped with only a linear polarized antenna to read information recorded in a radio IC tag  6 T from two directions at right angles to each other. 
     Except the above-mentioned, a configuration of the second variation is similar to that of the second embodiment, and its detailed description is omitted herefrom. 
     The second antenna  62  (including a second antenna first part  62   a  and a second antenna second part  62   b ) according to the second variation of the second embodiment has a configuration similar to that of the second antenna  42  according to the second embodiment. 
     As shown in  FIG. 11 , a base material  64  of the radio IC tag  6 T has a substantial L shape and includes, via a slot  62   s , a base material first part  64   a  substantially facing the second antenna first part first area  62   a   1  and the second antenna second part  62   b , and a base material second part  64   b  facing a second antenna first part second area  62   a   2  and the second antenna second part  62   b.    
     The first antenna  61  is substantially L-shaped having a substantial right angle and contouring the substantially L-shaped base material  64 . The first antenna  61  includes: a first antenna first area  61   a  mounted on the base material first part  64   a ; and a first antenna second area  61   b  mounted on the base material second part  64   b , combination of which forms a substantial L shape. 
     The first antenna first area  61   a  of the first antenna  61  is arranged facing the second antenna first part first area  62   a   1  and the second antenna second part  62   b . The first antenna second area  61   b  of the first antenna  61  is arranged facing the second antenna first part second area  62   a   2  and the second antenna second part  62   b.    
     Further, the first antenna first area  61   a  of the first antenna  61  is faced to and placed over a slot first area  62   s   1  (which may also be referred to as a second gap first area) of the substantially L-shaped slot  62   s  of the second antenna  62 . The first antenna second area  61   b  of the first antenna  61  is faced to and placed over a slot second area  62   s   2  (which may also be referred to as a second gap second area) of the slot  62   s  of the second antenna  62 . 
     As described above, the first antenna  61  of a radio IC tag  6 T is placed over the second antenna  62 . Further, an IC chip  63  of the radio IC tag  6 T and an L-shaped slit  61   s  of the first antenna  61  are arranged not vertically facing or being placed over the substantially L-shaped slot  62   s  of the second antenna  62 . 
     With the configuration according to the second variation of the second embodiment, the first antenna  61  of the radio IC tag  6 T is substantially L-shaped having a substantially right angle and crosses the second antenna  62  and the slot  62   s  in the second antenna  62 . This enables a reader/writer (not shown) equipped with a linear polarized antenna to read information recorded in the radio IC tag  6 T from two directions at right angles to each other. 
     Third Embodiment 
     Next is described a third embodiment with reference to  FIGS. 12A and 12B . 
       FIG. 12A  is a view in the direction of the arrow B in  FIG. 1B  according to the third embodiment.  FIG. 12B  is a plan view illustrating a second antenna  72  of  FIG. 12A . 
     The third embodiment has a configuration in which the second antenna first and second parts  2   a ,  2   b , according to the first embodiment are unitarily formed. 
     Except the above-mentioned, the configuration of the third embodiment is similar to that of the first embodiment, and its detailed description is omitted herefrom. 
     As shown in  FIG. 12A  and  FIG. 12B , the second antenna  72  according to the third embodiment includes a second antenna first area  72   a , a second antenna second area  72   b , and a second antenna third area  72   c . The second antenna first area  72   a  and the second antenna second area  72   b  are disposed across a slot  72   s . The second antenna third area  72   c  is an area which does not face the radio IC tag  7 T. The second antenna first area  72   a  and the second antenna second area  72   b  are unitarily formed via the second antenna third area  72   c.    
     As shown in  FIG. 12A , the first antenna  71  is faced to and is placed over the second antenna  72 . Further, an IC chip  73  of the radio IC tag  7 T and a L-type slit  71   s  of the antenna  71  are arranged without facing to and being positioned over the slot  72   s  of the second antenna  72 . 
     &lt;Advantages&gt; 
     With the configuration of the third embodiment, in addition to the advantages of the first embodiment, the radio IC tag  7 T can fulfill its functions even if the product P to which the radio IC tag  7 T is attached is made of either resin or metal. This is because the second antenna  72  is configured as a single unit via the second antenna third area  72   c , which enhances a function of the dipole mode. 
     &lt;First Variation of Third Embodiment&gt; 
     Next is described a first variation of the third embodiment with reference to  FIGS. 13A and 13B . 
       FIG. 13A  is a view in the direction of the arrow B in  FIG. 1B  according to the first variation of the third embodiment.  FIG. 13B  is a plan view illustrating a second antenna  82  of  FIG. 13A . 
     The first variation of the third embodiment has a configuration in which the slot  72   s  (see  FIG. 12 ) of the second antenna  72  according to the third embodiment is changed to a plurality of slots  82   s   1 ,  82   s   2 ,  82   s   3 ,  82   s   4 , so as to be less recognizable. 
     Except the above-mentioned, a configuration of the first variation is similar to that of the third embodiment, and its detailed description is omitted herefrom. 
     As shown in  FIG. 13B , in the first variation, a plurality of slots  82   s   2 ,  82   s   3 ,  82   s   4  are formed in a second antenna second area  82   b  of the second antenna  82 , in addition to a slot  82   s   1  which is similar to the slot  72   s   1  according to the third embodiment. 
     The second antenna  82  includes a second antenna first area  82   a , the second antenna second area  82   b , and a second antenna third area  82   c . The second antenna first area  82   a  and the second antenna second area  82   b  are unitarily formed via the second antenna third area  82   c  which is disposed in a position without vertically facing the radio IC tag  8 T. 
     With the above configuration of the first variation, the slots  82   s   2 ,  82   s   3 ,  82   s   4  are formed in the second antenna  82 . Thus, when a user sees the second antenna  82 , the increased number of the slots  82   s   2 ,  82   s   3 ,  82   s   4 , in a wider area reduces a contrast change in the second antenna  82 , compared to a single slot. This makes the slots  82   s   2 ,  82   s   3 ,  82   s   4 , less recognizable by the user and improves designing. 
     Fourth Embodiment 
     Next is described a fourth embodiment with reference to  FIGS. 14A ,  14   b ,  15 A, and  15 B. 
       FIG. 14A  is a perspective view illustrating an IC chip medium  9 P with a radio IC tag  9 T embedded therein according to the fourth embodiment.  FIG. 14B  is a cross sectional view illustrating the radio IC tag T when cut along the line D-D of  FIG. 14A . 
       FIG. 15A  is a perspective view illustrating another IC chip medium  9 P, such as a sheet of paper, with the radio IC tag  9 T shown in  FIG. 14A  embedded therein and with a hologram  9 H as a second antenna  92  disposed facing the IC chip medium  9 P.  FIG. 15B  is a cross sectional view illustrating the radio IC tag T when cut along the line E-E of  FIG. 15A . 
     The fourth embodiment has a configuration in which the hologram  9 H as the second antenna  92  is arranged facing the medium  9 P such as a sheet of paper with the radio IC tag  9 T embedded therein. 
     As shown in  FIG. 14A  and  FIG. 14B , the radio IC tag  9 T with information recorded therein is embedded in the medium  9 P such as an important document and a certificate so as to prevent forgery, manage security, or the like. 
     As shown in  FIG. 15A  and  FIG. 15B , the hologram  9 H (made of a hologram seal or hologram foil) as the second antenna  92  is attached onto a surface of the medium  9 P. The medium  9 P is a sheet of paper 150 μm thick and is equipped with the radio IC tag  9 T which is embedded therein beforehand in the paper forming process. The hologram  9 H is attached to the medium  9 P such that the second antenna  92  (including a second antenna first part  92   a  and a second antenna second part  92   b ) is positioned vertically above a first antenna  91  of the radio IC tag  9 T. 
     As shown in  FIG. 15B , the medium  9 P made of paper such as an important document and a certificate serves as an insulating layer between the first antenna  91  of the radio IC tag  9 T and the hologram  9 H as the second antenna  92 . 
     If the hologram  9 H as the second antenna  92  is a hologram seal, an adhesive layer is formed on an under surface of the hologram  9 H, with which the hologram  9 H is firmly fixed to the medium  9 P. 
     Alternatively, if the hologram  9 H is made of hologram foil, the foil-processed hologram  9 H is fixed to a sheet of paper or the like with thermo compression bonding. 
     In other words, the radio IC tag  9 T may be equipped in the product P by embedding a piece equipped with the IC chip  93  in the first antenna  91  formed on a base material in the paper forming process (see  FIGS. 14A and 14B ) or by inserting a piece equipped with the IC chip  93  between more than two sheets of paper (the product  9 P). 
     Additionally, the radio IC tag  9 T may be equipped in the product P at high speed by using a thread  94  (see  FIGS. 15A and 15B ) with the radio IC tags  9 T arranged thereon when embedding the radio IC tag  9 T (see  FIGS. 14A and 14B ) in the paper forming process. The thread with the radio IC tags  9 T is prepared by using a tape-shaped thread made of resin or paper having a width of 2 to 5 mm and successively arranging the radio IC tags  9 T on the thread at desired intervals. In this case, a base material  94  of the radio IC tag  9 T (indicated with a alternate long and two short dashes line in  FIG. 15B ) serves as a material for the thread. 
     The prepared tape-shaped thin thread equipped with the radio IC tag  9 T having the IC chip  93  and the first antenna  91  is embedded in the medium  9 P in the paper forming process or inserted between more than two sheets of paper as the medium  9 P. 
     &lt;Advantages&gt; 
     With the fourth embodiment, the hologram  9 H is arranged facing the radio IC tag  9 T embedded in the medium  9 P. This allows a metal evaporated layer of the hologram  9 H to be used as the second antenna  92 . 
     Therefore, information recorded in the radio IC tag  9 T can prevent forgery of the medium  9 P such as an important document and a certificate. The hologram  9 H also has such a forgery preventive property. Moreover, the hologram  9 H can add a decorative appearance to the medium  9 P. 
     Further, if the hologram  9 H is made of hologram foil, the hologram foil is too thin to be easily removed, which enhances forgery prevention effect. 
     The configurations according to the first to fourth embodiments and their variations are described above individually. However, any appropriate combination thereof is also possible, and advantages resulting from the combination can be obtained. 
     Description of the embodiments of the present invention has been made assuming that the product P is made of metal or resin and the medium  9 P is made of paper such as an important document and a certificate. However, the present invention can be applied to any other solid material. 
     In the first to fourth embodiments, description has been made assuming that the radio IC tag is a read-only radio IC tag. However, the present invention can be applied to a readable and writable radio IC. 
     Various dimensions provided in the embodiments, such as widths of the slots are only by way of examples, and the present invention is not limited to those. 
     The embodiments according to the present invention have been explained as aforementioned. However, the embodiments of the present invention are not limited to those explanations, and those skilled in the art ascertain the essential characteristics of the present invention and can make the various modifications and variations to the present invention to adapt it to various usages and conditions without departing from the spirit and scope of the claims.