Patent Publication Number: US-9905927-B2

Title: Antenna device, circuit board and memory card

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a divisional application of and claims the benefit of priority under 35 U.S.C. 120 to the patent application Ser. No. 13/417,513 filed on Mar. 12, 2012, which was based upon and claims the benefit of priority of Japanese Patent Application No. 2011-073642 filed on Mar. 29, 2011, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an antenna device, a circuit board and a memory card. 
     2. Description of the Related Art 
     An image, a video or the like is captured by a camera or the like, and the captured image, the video or the like may be stored in a recording medium installed in the camera or the like. However, because the recording medium is ordinarily installed inside the camera, there is an upper limit in a memory capacity. Therefore, an image or a video having a predetermined period of time or longer may not be stored in the camera. 
     In order to transfer information to a recording medium having a large capacity from a camera, an antenna for wireless communication is installed inside the camera. For example, a memory card in which an antenna for wireless communication is installed may be used. 
     Problems to be Solved by the Invention 
     When such a memory card is installed in the camera or the like, the antenna does not ordinarily protrude from the body of the camera or the like. For example, a camera body includes a metallic case and a memory card may be surrounded by the metallic case and further by an electronic circuit board including a conductive portion. Therefore, when the memory card having the antenna is installed in the camera, it may be difficult to send information by wireless communication from the inside of the camera to the outside of the camera. In this case, the information may not be accurately sent, or a spatial area where the information can be sent may be limited. 
     [Patent Document 1] Japanese Laid-open Patent Publication No. 2001-266098 
     [Patent Document 2] Japanese Laid-open Patent Publication No. 2006-18624 
     [Patent Document 3] Japanese Laid-open Patent Publication No. 2007-299338 
     [Patent Document 4] Japanese Laid-open Patent Publication No. 2008-83868 
     [Patent Document 5] Japanese Laid-open Patent Publication No. 2011-22640 
     [Patent Document 6] International Publication Pamphlet No. 2007/125948 
     [Patent Document 7] International Publication Pamphlet No. 2008/038756 
     SUMMARY OF THE INVENTION 
     Accordingly, embodiments of the present invention may provide a novel and useful antenna device, a circuit board and a memory card solving one or more of the problems discussed above. 
     More specifically, the embodiments of the present invention may provide a high communication performance even if the antenna device, the circuit board and the memory card are installed inside cases of information technology devices. 
     An aspect of the present invention may be to provide an antenna device including a substrate made of a dielectric material; an antenna element formed on one side of the substrate; and a ground element formed on another side of the substrate. 
     Another aspect of the present invention may be to provide an antenna device including a substrate made of a dielectric material; an antenna element formed on one side of the substrate; and a ground element formed on another side of the substrate. 
     Another aspect of the present invention may be to provide the antenna device, wherein a shape of the antenna element and a shape of the ground element are substantially symmetrical with respect to the substrate. 
     Another aspect of the present invention may be to provide the antenna device, wherein a position of the antenna element and a position of the ground element are substantially symmetrical with respect to the substrate. 
     Another aspect of the present invention may be to provide the antenna device, wherein a position of the antenna element and a position of the ground element are do not overlap through to the substrate. 
     Another aspect of the present invention may be to provide the antenna device, wherein the antenna element and the ground element are in an inverse L shape. 
     Another aspect of the present invention may be to provide the antenna device, wherein the antenna element is connected to the ground element via a through hole formed in the substrate. 
     Another aspect of the present invention may be to provide the antenna device, wherein the antenna element is in an inverse F shape, and the ground element substantially occupies a surface on the other side of the substrate in its entirety. 
     Another aspect of the present invention may be to provide the antenna device, wherein a shape of the antenna element and a shape of the ground element are a meander pattern. 
     Another aspect of the present invention may be to provide the antenna device, wherein the substrate is a printed-wiring board. 
     Another aspect of the present invention may be to provide the antenna device, wherein an inductor for adjusting a resonance frequency is connected to the antenna element and the ground element. 
     Another aspect of the present invention may be to provide the antenna device, wherein the substrate is a multi-layered printed-wiring board, and one or both of the antenna element and the ground element are formed inside the printed-wiring board. 
     Another aspect of the present invention may be to provide the antenna device, wherein the substrate is a multi-layered printed-wiring board, the antenna element includes a first antenna element formed inside the printed-wiring board and a second antenna element formed on the other side of the printed-wiring board, and an antenna element connecting portion formed inside a through hole; the ground element includes a first ground element formed inside the printed-wiring board and a second ground element formed on the other side of the printed-wiring board, and a ground element connecting portion formed inside another through hole. 
     Another aspect of the present invention may be to provide the antenna device, wherein the first antenna element and the first ground element are formed in a region where the second antenna element overlaps the second ground element through a thickness of the substrate. 
     Another aspect of the present invention may be to provide the antenna device, wherein any one of the first antenna element, the second antenna element, the first ground element and the second ground element does not overlap another one of the first antenna element, the second antenna element, the first ground element and the second ground element through a thickness of the substrate. 
     Another aspect of the present invention may be to provide the antenna device, wherein the antenna device is configured to be used in a frequency range of 2.4 GHz to 2.5 GHz. 
     Another aspect of the present invention may be to provide the antenna device, wherein the antenna device is used for wireless LAN or Bluetooth. 
     Another aspect of the present invention may be to provide a circuit board including an antenna device including a first printed-wiring board made of a dielectric material; an antenna element formed on one side of the first printed-wiring board; and a ground element formed on another side of the first printed-wiring board; and a second printed-wiring board on which a ground area is formed, wherein the ground element is connected to the ground area. 
     Another aspect of the present invention may be to provide the circuit board, wherein the ground element is formed on a second printed-wiring board instead of the first printed-wiring board. 
     Another aspect of the present invention may be to provide the circuit board, wherein the second printed-wiring board has an electronic component mounted on the second printed-wiring board. 
     Another aspect of the present invention may be to provide a memory card including a circuit board including a substrate made of a dielectric material; an antenna element formed on one side of the substrate; and a ground element formed on another side of the substrate; and a case configured to cover the circuit board. 
     Additional objects and advantages of the embodiments are set forth in part in the description which follows, and in part will become obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a structure of an antenna device of a First Embodiment; 
         FIG. 2  illustrates a structure of a circuit board of the First Embodiment; 
         FIG. 3  schematically illustrates a part of the antenna device of the First Embodiment; 
         FIG. 4  illustrates a structure of a memory card of the First Embodiment; 
         FIG. 5  is a perspective view of a digital camera for illustrating a part of receiving the memory card. 
         FIG. 6  schematically illustrates excitation in the antenna device of the First Embodiment; 
         FIG. 7  is a perspective view of the antenna device of the First Embodiment for explaining the excitation; 
         FIG. 8  schematically illustrates a part of another antenna device of the First Embodiment; 
         FIG. 9  illustrates a first structure of the circuit board of the First Embodiment; 
         FIG. 10  illustrates a second structure of the circuit board of the First Embodiment; 
         FIG. 11  illustrates a third structure of the circuit board of the First Embodiment; 
         FIG. 12  schematically illustrates a part of another antenna device of the First Embodiment; 
         FIG. 13  is a perspective view of the digital camera in which the memory card is installed; 
         FIG. 14  illustrates the structure of the circuit board used in measuring propagation in the First Embodiment; 
         FIG. 15  illustrates a method of measuring the propagation; 
         FIG. 16  illustrates a result of the measured propagation; 
         FIG. 17  is a first characteristic diagram of a propagation loss S 21  of the digital camera in which the memory card of Embodiment 1 is installed; 
         FIG. 18  is a second characteristic diagram of a propagation loss S 21  of the digital camera in which the memory card of Embodiment 1 is installed; 
         FIG. 19  illustrates the structure of a circuit board of a Second Embodiment; 
         FIG. 20  is a VSWR characteristic diagram of the circuit board of the Second Embodiment; 
         FIG. 21  illustrates a structure of a circuit board used in measuring propagation in the Second Embodiment; 
         FIG. 22  is a characteristic diagram of a propagation loss S 21  of a digital camera in which a memory card of the Second Embodiment is installed; 
         FIG. 23  illustrates a structure of an antenna device of a Third Embodiment; 
         FIG. 24  is an equivalent circuit schematic of an antenna device of the Third Embodiment; 
         FIG. 25  schematically illustrates a part of another antenna device of the Third Embodiment; 
         FIG. 26  is a VSWR characteristic diagram of the circuit board of the Second Embodiment; 
         FIG. 27  illustrates a structure of an antenna device of a Fourth Embodiment; 
         FIG. 28  illustrates a first structure of the circuit board of the Fourth Embodiment; 
         FIG. 29  illustrates a second structure of the circuit board of the Fourth Embodiment; 
         FIG. 30  illustrates a third structure of the circuit board of the Fourth Embodiment; 
         FIG. 31  illustrates a structure of an antenna device having no meander pattern; 
         FIG. 32  is a VSWR characteristic diagram of the circuit board of the Fourth Embodiment; 
         FIG. 33  illustrates a structure of an antenna device of a Fifth Embodiment; 
         FIG. 34  schematically illustrates a part of the antenna device of the First Embodiment; 
         FIG. 35  is a VSWR characteristic diagram of the circuit board of the Fifth Embodiment; 
         FIG. 36  illustrates a structure of an antenna device of a Sixth Embodiment; 
         FIG. 37  schematically illustrates a part of the antenna device of the Sixth Embodiment; 
         FIG. 38  schematically illustrates a first structure of another antenna device of the Sixth Embodiment; 
         FIG. 39  schematically illustrates a part of the first structure of the other antenna device of the Sixth Embodiment; 
         FIG. 40  schematically illustrates a second structure of another antenna device of the Sixth Embodiment; and 
         FIG. 41  schematically illustrates a part of the second structure of another antenna device of the Sixth Embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description of embodiments of the present invention is given below, with reference to the  FIG. 1  through  FIG. 40 . The same reference symbols are attached to the same components or the like and description of the components is omitted. 
     The reference symbols typically designate as follows:
       100 : antenna device;     110 : printed-wiring board;     120 : antenna element;     130 : ground element;     200 : circuit board;     210 : ground area;     211 : printed-wiring board;     212 : external connection terminal;     250 : memory card;     260 : first case;     262 : opening portion; and     270 : second case.   

     First Embodiment 
     (Antenna Device and Circuit Board) 
     The antenna device and the circuit board of the First Embodiment are described. Referring to  FIG. 1 , the antenna device  100  of the First Embodiment has an antenna element  120  on one side of a substrate such as a printed-wiring board  110 , and a ground element  130  on the other side of the substrate. The sides are determined relative to a thickness center of the substrate such as the printed-wiring board  110 . 
     The antenna element  120  and the ground element  130  are made of a metallic material such as copper. The antenna element  120  and the ground element  130  are symmetrical with respect to the printed-wiring board  110 . The ground element  130  of the antenna device  100  is grounded, and a high-frequency voltage of, for example, 2.4 GHz to 2.5 GHz is applied to the antenna element  12 . 
     The antenna device of the First Embodiment may be used for communications in a frequency range of 2.4 GHz to 2.5 GHz, in wireless LAN or in Bluetooth (BT) (“Bluetooth” is a registered trademark). In the antenna device of the First Embodiment, inductors having predetermined inductances may be connected to the antenna element  120  and the ground element  130 , respectively, in order to adjust a resonance frequency. 
     Within the First Embodiment, the printed-wiring board  110  is made of a glass epoxy resin having a thickness of about 0.8 mm. For example, the printed wiring board  110  includes a FR4 substrate whose relative permittivity ∈ r  is about 4.7. The antenna element  120  and the ground element  130  are formed to have an inverse L shape (hereinafter, it may be referred to as an inverse L type) so as to be substantially symmetrical with respect to the printed wiring board. Specifically, patterns of the antenna element  120  and the ground element  130  may be formed in a similar manner to a case where the wiring pattern made of copper is formed. Meanwhile, in the First Embodiment, a case where the printed-wiring board  110  is used is described. However, a board made of another dielectric material such as a ceramics board formed by AlN, Al 2 O 3  or the like and a plastic board may be used. 
     Referring to  FIG. 2 , the circuit board  200  includes an antenna device  100  of the First Embodiment. Specifically, a ground (GND) area  210  is formed on a surface of a printed-wiring board  211  forming the circuit board  200  and the ground area  210  is grounded. Further, the ground area  210  is connected to the ground element  130  of the antenna  100 . Within the First Embodiment, the circuit board such as the circuit board  200  has the antenna device  100 . 
     Next, a positional relationship between the antenna element  120  and the ground element  130  in the antenna device  100  of the First Embodiment is described.  FIG. 3  illustrates a part of a cross-section cut along a dot chain line  1 A- 1 B in  FIG. 1 . Referring to  FIG. 3 , the antenna element  120  and the ground element  130  are formed on both surfaces of the printed-wiring board  110  so as to be symmetrical with respect to the printed-wiring board  110 . In this case, by applying a high-frequency voltage to the antenna element  120 , an electric field occurs between the antenna element  120  and the ground element  130  in a direction indicated by an arrow in  FIG. 3 . Said differently, the electric field is generated in a thickness direction of the printed-wiring board  110 . 
     (Memory Card) 
     Next, a memory card of the First Embodiment is described. A secure Digital (SD) card is exemplified as the memory card of the First Embodiment. However, the invention is applicable to memory cards in other standards and other types. 
     Referring to  FIG. 4 , the memory card  250  of the First Embodiment includes a circuit board  200  in which an antenna device  100  is installed, a first case  260  made of a resin material such as a plastic, and a second case  270 . The circuit board  200  is accommodated in a space covered by a first case  260  and a second case  270 . The circuit board  200  has an external connection terminal  212  to be connected to a memory card socket inside the digital camera. Further, an electronic circuit or the like is installed in the circuit board  200 . An opening portion  262  is formed in the first case  260  so as to expose the external connection terminal  212  to an outside. The memory card  250  is formed by joining the first case  260  to the second case  270  so as to cover the circuit board  200 . 
     The antenna device  100  of the memory card  250  of the First embodiment is provided in an end portion of the circuit board  200  opposite to an end portion where the external connection terminal  212  is provided. Since the external connection terminal  212  is connected to the memory card socket, the external connection terminal can intrude into an inside of a digital camera or the like. Therefore, the antenna device  100  is formed on an outer side of the digital camera or the like in the vicinity of a loading slot of the memory card, whose side is opposite to the side where the external connection terminal  212  is provided. 
     Referring to  FIG. 5 , when the digital camera  300  is loaded with the memory card  250 , the loading slot is covered by a lid  310  provided in the digital camera  300 . Therefore, the memory card  250  is enclosed by the casing of the digital camera  300 , the memory card socket and the lid  310 . Under the condition, the casing of the digital camera  300 , the memory card socket and so on may form a so-called wave guide tube. Referring to  FIG. 6 , when the digital camera is loaded with the memory card  250  including the circuit board  200  having the antenna device  100 , it is possible that an antenna exists inside the wave guide tube  350  formed by the casing of the digital camera. Because electromagnetic waves generated by excitation in a direction of an arrow A are shielded by the wave guide tube  350 , the electromagnetic waves are only minimally emitted into the outside of the wave guide tube. However, the electromagnetic waves generated by excitation in a direction indicated by an arrow B proceeds inside the wave guide tube  350  and emitted outside the wave guide tube  350  from an opening portion  360  of the wave guide tube  350 . 
     The thickness of a portion such as the lid  310  where the memory card  250  is inserted is thin, and is sometimes made of a material other than a metal. Therefore, it is possible to consider that the opening portion  360  of the wave guide tube  350  is formed in a direction of insertion of the memory card  250 . Accordingly, the electromagnetic waves generated by the excitation in the directions indicated by the arrows B from the opening portion  360  are supposed to be emitted outside the wave guide tube  350  of the digital camera  300 . 
     Referring to  FIG. 7 , the electric field is applied to the printed-wiring board  110  in the thickness direction (the arrows B) of the printed-wiring board  110  of the memory card  250  of the First Embodiment. Accordingly, the electromagnetic waves generated in the antenna device  100  can be emitted outside the digital camera  300 . Because of this, the emitted electromagnetic waves can maintain high intensity. 
     (Modified Example of Antenna Device) 
     Further, referring to  FIG. 8 , the antenna device of the First Embodiment may be formed so that the position of the antenna element  120  shifts from the position of the ground element  130  with respect to the printed-wiring board  110  (an asymmetrical positional relationship). By shifting the position of the antenna element  120  from the position of the ground element  130 , when a high-frequency voltage is applied to the antenna element  120 , the electric field generated by the high-frequency voltage leaks from an area where the positions shift. Because the electromagnetic wave generated by the leaking electromagnetic field is generated by excitation in directions different from the thickness directions of the printed-wiring board  110 , it may be possible to more effectively emit the electromagnetic wave to the outside of the casing of the digital camera, depending on a type of the digital camera used. 
     (Manufacturing Method of Antenna Device and Circuit Board) 
     Next, the manufacturing methods of the antenna device and the circuit board of the First Embodiment are described. 
     Referring to  FIG. 9 , the circuit board  200  of the First Embodiment may be formed by bonding the antenna device  100 , which includes the printed-wiring board  110  on both surfaces of which the antenna element  120  and the ground element  130  are formed, to a predetermined position of the printed-wiring board  211  on which a ground area  210  is formed. Further, the ground element  130  is connected to the ground area  210 . 
     Further, referring to  FIG. 10 , the circuit board  201  of the First Embodiment may be formed by bonding a printed-wiring board  110  having the antenna element  120  on one surface of the printed-wiring board to a printed-wiring board  211  having a ground area  210 , and a ground element  230  connected to the ground area  210  so that the other surface of the printed-wiring board  110  faces the ground element  230  of the printed-wiring board  211 . 
     Referring to  FIG. 11 , the circuit board  201 - 1  of the First Embodiment may be structured to have an antenna element  220  on one surface of the printed wiring board  211 , and a ground element  230  and a ground area  210  connected to the ground element on the other surface of the printed wiring board  211 . With this structure, the number of the printed-wiring board is one to thereby enable obtaining the circuit board having the antenna device at a lower cost. 
     Functionally, the antenna element  220  corresponds to the antenna element  120 , and the ground element  230  corresponds to the ground element  130 . 
     The shape of the antenna device  102  is not limited to the inverse L shape and may be a T shape. Specifically, referring to  FIG. 12 , an antenna element  121  in a T-like shape is formed on one surface of the printed-wiring board  110  and a ground element  131  in a T-like shape may be formed on the other surface of the printed wiring board  110 . 
     In the First Embodiment, an electronic circuit or the like may be formed on the printed-wiring board  211 . However, the electronic circuit or the like is omitted in the figures. Specifically, there may be cases where the electronic circuit or the like is formed in an area where there is no ground area or where the printed-wiring board  211  has a multilayer structure and an electronic circuit or the like is formed inside the multilayer structure. 
     (Propagation Characteristics) 
     Next, propagation characteristics of electromagnetic waves in the antenna device, the circuit board and the memory card of the First Embodiment are described. Specifically, the digital camera  300  loaded with the memory card  250  including the circuit board  200  of the First Embodiment as illustrated in  FIG. 14  is measured to obtain the propagation characteristics of electromagnetic waves. Referring to the circuit board  200  illustrated in  FIG. 14 , the thickness and the width of the printed-wiring board  110  forming the antenna device  100  are 1 mm and 4 mm, respectively, and the size of the circuit board  200  is 20 mm×29 mm. 
     The measurement method of the propagation characteristics is such that a digital camera  300  and a standard antenna  510  are provided in a dark box  500  as illustrated in  FIG. 15 . From an antenna device  100  of the memory card  250  in the digital camera  300 , a high frequency signal of 2.45 GHz is generated and sent to a standard antenna  510  located apart by 25 cm from the digital camera  300 . The standard antenna  510  receives the high frequency signal of 2.45 GHz. The received electromagnetic waves are measured by a propagation loss S 21  measurement instrument  520  installed outside the dark box  500 . Referring to  FIG. 13 , the standard antenna  510  is arranged on a front side (on a side of a lens mounted in the digital camera), a back side, a right side, a left side, an up side and a down side. The distance between the digital camera  300  and the standard antennas  510  was 25 cm and a space loss was 28 dB. 
       FIG. 16  illustrates propagation characteristics measured in a case where the memory cards  250  of the First Embodiment are used for two digital cameras, respectively, and in a case where conventional memory cards having antennas are used for these digital cameras, respectively. The propagation loss S 21  of the digital camera A loaded with the conventional memory card with the antenna was −52.7 dB to −43.7 dB. Meanwhile, the propagation loss S 21  of the digital camera A loaded with the memory card with the antenna of the First Embodiment was −53.2 dB to −42.1 dB. Thus, the propagation loss S 21  can be reduced in the memory card with the antenna of the First Embodiment. The propagation loss S 21  of the digital camera B loaded with the conventional memory card with the antenna was −54.3 dB to −48.0 dB. Meanwhile, the propagation loss S 21  of the digital camera B loaded with the memory card with the antenna of the First Embodiment was −52.7 dB to −40.2 dB. Thus, again, the propagation loss S 21  can be reduced in the memory card with the antenna of the First Embodiment. 
       FIG. 17  illustrates a relationship between the frequency and the propagation loss S 21  on the front side, the back side, the right side, the left side, the upper side, and the lower side in the digital camera A. In a case where the digital camera A is loaded with the memory card  250  of the First Embodiment, the propagation losses in the frequency of 2.4 to 2.5 GHz on the down side, the upper side and the front side are relatively low and the propagation losses in the frequency of 2.4 to 2.5 GHz on the back side, the right side and the left side are relatively high. 
       FIG. 18  illustrates a relationship between the frequency and the propagation loss S 21  on the front side, the back side, the right side, the left side, the upper side and the lower side in the digital camera B. In a case where the digital camera B is loaded with the memory card  250  of the First Embodiment, the propagation losses in the frequency of 2.4 to 2.5 GHz on the down side, the right side and the front side are relatively low, the propagation loss in the frequency of 2.4 to 2.5 GHz on the back side is neutral, and the propagation losses in the frequency of 2.4 to 2.5 GHz on the left side and the upper side are relatively high. 
     As described, by using the memory card of the First Embodiment, the propagation loss can be reduced with respect to the type of digital camera and the sides where the antenna is mounted. With this, the electromagnetic waves can be emitted outside the digital camera with a small propagation loss. 
     Meanwhile, because the memory card of the First Embodiment is shaped to be substantially the same as a memory card such as an SD card, it is referred to as the memory card. However, this memory card could potentially not include a memory as a recording medium. 
     Second Embodiment 
     The Second Embodiment is described next. In the Second Embodiment, the circuit board and the memory card in which the antenna device is installed are described. Referring to  FIG. 19 , an antenna device  103  of a circuit board  202  of the Second Embodiment includes an antenna element  122  formed on one surface of a printed-wiring board  110  and a ground element  132  formed in the other surface of the printed-wiring board  110  in its entirety. The antenna element  122  includes a first side antenna element  123  on a side surface of the printed-wiring board  110  and a second side surface antenna element  124  on the side surface of the printed-wiring board  110  to thereby form an inverse F shape (hereinafter, the antenna formed in the inverse F shape may be referred to as the antenna of the inverse F type). The first side antenna element  123  is connected to the ground element  132  formed on the printed-wiring board  110  so as to be applied with a high-frequency voltage greater than that to the antenna element  124 . The ground element  132  on the surface of the printed-wiring board  211  is connected to the ground area  210  formed on the surface of the printed-wiring board  210 . 
     Voltage Standing Wave Ratio (VSWR) characteristics of the circuit board  202  of the Second Embodiment are illustrated in  FIG. 20 . The lower the value of the VSWR, the smaller the reflection. In the circuit board  202 , the value of VSWR is 2 or smaller in the vicinity of the frequency of 2.4 GHz. Therefore, the VSWR characteristics were good. 
     The memory card is prepared in a similar manner to the First Embodiment, but this time using the circuit board  202  of the Second Embodiment. A digital camera illustrated in  FIG. 13  is loaded with the memory card of the Second Embodiment. A propagation loss S 21  of the digital camera is measured in a similar manner to the method of the First Embodiment. In the Second Embodiment, the digital camera is the digital camera A of the First Embodiment. The circuit board  202  is formed as illustrated in  FIG. 21 . The thickness of the printed-wiring board  110  is 1 mm, the width thereof is 4 mm, the size thereof is 20 mm×29 mm. 
       FIG. 22  illustrates a relationship between the frequency and the propagation loss S 21  on the front side, the back side, the right side, the left side, the upper side and the lower side. When the digital camera A is loaded with the memory card of the Second Embodiment, the propagation loss in the frequency of 2.4 to 2.5 GHz is the smallest on the back side and the propagation loss on the bottom side, that on the front side, that on the left side, that on the right side and that on the upper side increase in this order. The propagation loss in the frequency of 2.45 GHz was −54.7 to −42.6 dB. The other portions are the same as those in the First Embodiment. 
     Third Embodiment 
     The Third Embodiment is described next. An antenna device  104  of the Third Embodiment is a dipole antenna in which an antenna element and a ground element are connected. Specifically, referring to  FIG. 23 , a connecting portion  140  made of a metal such as copper is formed inside a through hole provided in a printed-wiring board  110  to connect the antenna element  20  to the ground element  130 . Thus, the dipole element is formed. As described, by connecting the antenna element  120  to the ground element  130  by the connecting portion  140 , the equivalent circuit becomes as illustrated in  FIG. 24  enabling adjusting resonance. 
     A position where the connecting portion  140  (the throughhole) is determined by a resonance frequency or the like. For example, referring to  FIG. 25 , the throughhole may be formed on end portions of the antenna element  120  and the ground element  130  and the connecting portion  140  is formed in the throughhole to thereby connect the antenna element  120  to the ground element  130 . 
     VSWR characteristics of a circuit board including the antenna device  104 - 1  illustrated in  FIG. 25  (with the through hole) prepared in a similar manner to the First Embodiment and a circuit board of the First Embodiment (without the through hole) are illustrated in  FIG. 26 . Referring to  FIG. 26 , by forming the throughhole to connect the antenna element  120  to the ground element  130  at a predetermined position by the connecting portion  140  in the throughhole, it is possible to shift the frequency range to a desired frequency band. With this, the frequency range can be easily and minutely adjusted. The other portions are the same as those in the First Embodiment. 
     Fourth Embodiment 
     The Fourth Embodiment is described next. An antenna device  105  is formed so that an antenna element  125  and a ground element  135  have a meander shape as illustrated in  FIG. 27 . In the Fourth Embodiment, the shape is referred to as a meander pattern. 
     The antenna element  125  and the ground element  135  to be formed have substantially the same shape. By forming the antenna element  125  and the ground element  135  to be in a meander pattern, it is possible to form the antenna device so that the area on which the antenna is formed is not expanded much, and has a predetermined inductance. 
     (Manufacturing Method of Antenna Device and Circuit Board) 
     Next, the manufacturing methods of the antenna device and a circuit board  205  of the Fourth Embodiment are described. 
     Referring to  FIG. 28 , a circuit board  205  of the Fourth Embodiment may be formed by bonding the antenna device  105 , which includes the printed-wiring board  110  on both surfaces of which the antenna element  125  of the meander pattern and the ground element  135  of the meander pattern are formed, to a predetermined position of the printed-wiring board  211 , on which a ground area  210  is formed. Further, the ground element  135  is connected to the ground area  210 . 
     Further, referring to  FIG. 29 , the circuit board  206  of the Fourth Embodiment may be formed by bonding a printed-wiring board  110  having the antenna element  125  on one surface of the printed-wiring board  110  to a printed-wiring board  211  having a ground area  210  and a ground element  235  of the meander pattern connected to the ground area  210 , so that the other surface of the printed-wiring board  110  faces the ground element  235  of the printed-wiring board  211 . 
     Referring to  FIG. 30 , the circuit board  207  of the Fourth Embodiment may be configured to have an antenna element  225  of the meander pattern on one surface of the printed wiring board  211 , and a ground element  235  of the meander pattern and a ground area  210  connected to the ground element  235  on the other surface of the printed wiring board  211 . With this structure, the number of the printed-wiring board is only one, thereby obtaining a circuit board having the antenna device at a lower cost. 
     Functionally, the antenna element  225  corresponds to the antenna element  125 , and the ground element  235  corresponds to the ground element  135 . 
     VSWR characteristics of the circuit board  207  in which the antenna device having the meander pattern as illustrated in  FIG. 27  is formed and the circuit board in which the antenna device  107  without the meander pattern as illustrated in  FIG. 31  are illustrated in  FIG. 32 . Referring to  FIG. 32 , by forming the antenna element  125  of the meander pattern and the ground element  135  of the meander pattern, the value of VSWR can be further reduced. The antenna device  107  without the meander pattern is structured in a similar manner to the antenna device of the First Embodiment. However, in order to compare with the antenna device with the meander pattern illustrated in  FIG. 27 , the antenna device  107  is adjusted by conditions different from those of the First Embodiment. The other portions are the same as those in the First Embodiment. 
     Fifth Embodiment 
     The Fifth Embodiment is described next. An antenna device  108  of the Fifth Embodiment is configured to lower the resonance frequency by narrowing an interval between an antenna element  120  and a ground element  130  to increase an electrostatic capacitance. By lowering the resonance frequency, the antenna device  108  is adjusted for a predetermined frequency range. 
     Ordinarily, the printed-wiring board has a predetermined thickness to maintain predetermined strength. Therefore, there is a limit in increasing the electrostatic capacitance. Referring to  FIG. 33 , the antenna device  108  is configured to increase the electrostatic capacitance between the antenna element  120  and the ground element  130  by forming both the antenna element  120  and the ground element  130  inside a multilayer printed-wiring board  116 . It may be possible to form one of the antenna element  120  and the ground element  130  inside the printed-wiring board  116 . 
     Referring to  FIG. 34 , in the antenna device  108 , the interval (the distance) between the antenna element  120  and the ground element  130  can be reduced by using the printed-wiring board  116 . With this, the electrostatic capacitance between the antenna element  120  and the ground element  130  can be increased. Referring to (a) of  FIG. 34 , the antenna element  120  and the ground element  130  are formed on both sides of the printed-wiring board. Since the interval between the antenna element  120  and the ground element  130  are great, the electrostatic capacitance is not so large. On the contrary thereto, referring to (b) of  FIG. 34 , the antenna element  120  and the ground element  130  are formed inside the printed-wiring board  116 . The interval between the antenna element  120  and the ground element  130  are narrowed to thereby increase an electrostatic capacitance. 
       FIG. 35  illustrates VSWR characteristics in the antenna device  108 . The VSWR characteristics of the antenna device illustrated in  FIG. 34( a )  are indicated by  34 A, and the VSWR characteristics of the antenna device illustrated in  FIG. 34( b )  are indicated by  34 B. Referring to  FIG. 35 , by increasing the electrostatic capacitance between the antenna element  120  and the ground element  130 , the frequency range can be shifted to make the value of VSWR as small as possible. As described, when the value of the electrostatic capacitance is changed by narrowing the interval between the antenna element  120  and the ground element  130 , it is possible to shift the frequency range without substantially changing the frequency range. The other portions are the same as those in the First Embodiment. 
     Sixth Embodiment 
     The Sixth Embodiment is described next. The antenna device  109  is formed to set to a predetermined frequency range by increasing an inductance without widening an area where an antenna element  126  or the like is formed and lowering the frequency range to thereby set to a predetermined frequency range. 
     The structure of the antenna device  109  of the Sixth Embodiment is illustrated in  FIG. 36 . In the antenna device  109 , a multilayer printed-wiring board  116  is used, and the antenna element  126  and the ground element  136  are multi-layered. The antenna element  126  includes a first antenna element  126   a  formed inside the printed-wiring board  116  and a second antenna element  126   b  formed on one of surfaces of the printed-wiring board  116 . The first antenna element  126   a  and the second antenna element  126   b  are connected by an antenna element connecting portion  126   c  formed inside a throughhole for connecting the first antenna element  126   a  and the second antenna element  126   b.    
     The ground element  136  includes a first ground element  136   a  formed inside the printed-wiring board  116  and a second ground element  136   b  formed on the other one of surfaces of the printed-wiring board  116 . The first ground element  136   a  and the second ground element  136   b  are connected by a ground element connecting portion  136   c  formed inside a throughhole for connecting the first ground element  136   a  and the second ground element  136   b.    
     Within the Sixth Embodiment, without expanding an area inside the printed-wiring board  116  where the antenna element  126  or the like is formed, the inductances of the antenna element  126  and the ground element  136  can be increased. 
     Referring to  FIG. 37 , a cross-sectional view of an arrangement of the antenna element  126  and the ground element  136  of the antenna device illustrated in  FIG. 36  is schematically illustrated. The antenna element  126   a , the second antenna element  126   b , the first ground element  136   a  and the second ground element  136   b  are formed so that these entire areas overlap in the thickness direction of the antenna device  109 . Thus, when a high frequency electric signal is applied to the antenna element  126 , the antenna element  126  can be excited while the antenna elements match in the thickness direction of the printed-wiring board  116 . 
     Referring to  FIG. 38 , an antenna device  109 - 1  may have areas which do not overlap in the thickness direction of a printed-wiring board  116  by shifting positions of a first antenna element  126   a  and a second antenna element  126   b  and positions of a first ground element  136   a  and a second ground element  136   b . In this case, an electromagnetic field may leaks from the shifted areas of the first and second antenna elements and of the first and second ground element. Referring to  FIG. 39 , a cross-sectional view of an arrangement of the antenna element  126  and the ground element  136  of the antenna device illustrated in  FIG. 38  is schematically illustrated. 
     Further, referring to  FIG. 40 , it is also possible to provide an antenna device  109 - 2  in which an antenna element  126  shifts from a ground element  136  so as to form areas not overlapping each other. In this case, an electromagnetic field may leak from the shifted areas of first and second antenna elements and of first and second ground element. Referring to  FIG. 41 , a cross-sectional view of an arrangement of the antenna element  126  and the ground element  136  of the antenna device illustrated in  FIG. 40  is schematically illustrated. 
     When the inductance is increased in the antenna device, the meander patterns of the antenna elements and the ground elements are formed on both surfaces of the printed-wiring board  110  as in the antenna device of the Fourth Embodiment. However, within the Sixth Embodiment, the inductance can be increased without expanding the areas where the antenna element and the ground elements are formed in comparison with the antenna device with the meander pattern. Thus, the antenna device can be formed within a more narrow area. The other portions are the same as those in the First Embodiment. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of superiority or inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.