Abstract:
An antenna apparatus is disclosed. The antenna apparatus is structured by a ground plate that is shaped like a plate, and a feeding unit that is formed by a plate-like member, the feeding unit extending from the ground plate generally perpendicular to the ground plate at a predetermined angle to the ground plate for a predetermined length.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. application Ser. No. 11/119,732, filed May 3, 2005, and now pending, which further claims the benefit of priority of Japanese Patent Application No. 2004-271580 filed Sep. 17, 2004, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention generally relates to an antenna apparatus, and especially relates to an antenna apparatus that has a ground plate that is shaped like a plate, and a feeding unit that extends from the ground plate in a direction generally perpendicular to the ground plate at a predetermined offset angle for a predetermined length.  
         [0004]     2. Description of the Related Art  
         [0005]     In recent years and continuing, radio communications technology using UWB (ultra-wide band) attracts attention since radar positioning and communications with a large transmission capacity are possible. As for UWB, the U.S. FCC (Federal Communications Commission) allowed use of a 3.1-10.6 GHz band in 2002.  
         [0006]     Communications at UWB are performed by sending a pulse signal using a wide frequency band. Accordingly, an antenna apparatus used for UWB has to be capable of receiving a wide band signal.  
         [0007]     For UWB communications, at least in the 3.1-10.6 GHz frequency band approved by the FCC, an antenna apparatus consisting of a ground plate and a feeding unit is proposed (Non-patent Reference 1).  
         [0008]      FIG. 1A  shows a structure of a conventional antenna apparatus  10 .  
         [0009]     The antenna apparatus  10  shown in  FIG. 1A  includes a feeding unit  12  installed on a ground plate  11 , the feeding unit  12  being shaped like an inverted cone.  
         [0010]     In addition, the inverted cone that constitutes the feeding unit  12  is set up so that its side may form an angle θ to an axis  13  that perpendicularly intersects the ground plate  11 . A desired property is obtained by the angle θ.  
         [0011]     An antenna apparatus  20  shown in  FIG. 1B  includes a feeding unit  22  in the shape of a teardrop that includes an inverted cone  22   a , and a sphere  22   b  inscribed in the inverted cone  22   a  on the ground plate  11 .  
         [0012]     “An Omnidirectional and Low-VSWR Antenna for the FCC-Approved UWB Frequency Band”, Takuya Taniguchi and Takehiko Kobayashi (Tokyo Denki University) (Announced on Mar. 22, 2003 at classroom B201) The Electronic Information Communication Society 2003 B-1-133.  
         [0013]     However, since the conventional wideband-antenna apparatus is structured by the feeding unit having one of the inverted cone shape and the teardrop shape on the ground plate, the dimensions tend to be great. Then, an antenna apparatus that is smaller and thinner is desired.  
       SUMMARY OF THE INVENTION  
       [0014]     Accordingly, a general object of the present invention is to provide an antenna apparatus that is small and thin, substantially obviating one or more of the problems caused by the limitations and disadvantages of the related art.  
         [0015]     Features and advantages of the present invention are set forth in the description that follows, and in part will become apparent from the description and the accompanying drawings, or may be learned by practice of the invention according to the teachings provided in the description. Objects as well as other features and advantages of the present invention will be realized and attained by an antenna apparatus particularly pointed out in the specification in such full, clear, concise, and exact terms as to enable a person having ordinary skill in the art to practice the invention.  
         [0016]     To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides the antenna apparatus as follows.  
         [0017]     An aspect of the present invention provides the antenna apparatus including a ground plate that is shaped like a plate, and a feeding unit that extends from the ground plate in a direction that intersects perpendicularly with the ground plate for a predetermined length in a predetermined angle, wherein the feeding unit is shaped like a plate.  
         [0018]     According to another aspect of the present invention, an upper part of the plate constituting the feeding unit is sliced and removed, the upper part opposing the ground plate.  
         [0019]     According to another aspect of the present invention, the feeding unit is installed with its face being slanted relative to the ground plate.  
         [0020]     According to another aspect of the present invention, the feeding unit is installed such that it can rotate in directions parallel to the ground plate (about an axis perpendicular to the ground plate).  
         [0021]     According to another aspect of the present invention, the feeding unit is attached to the ground plate.  
         [0022]     According to another aspect of the present invention, the ground plate and the feeding unit are structured by a pattern for the ground plate and a pattern for the feeding unit, respectively, formed on a flexible printed wiring board, wherein the part of the pattern for the feeding unit is bent in reference to the part of the pattern for the ground plate such that the feeding unit is structured as extending from the ground plate perpendicular to the ground plate for a predetermined length.  
         [0023]     As described above, according to the present invention, since the feeding unit is structured by a plate that extends from the ground plate, the antenna apparatus can be made small and thin.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]      FIGS. 1A and 1B  are block diagrams of examples of conventional antenna apparatuses;  
         [0025]      FIG. 2  is a perspective diagram of the first embodiment of the present invention;  
         [0026]      FIG. 3  is an orthographic projection of the first embodiment of the present invention;  
         [0027]      FIG. 4  is a perspective diagram of the second embodiment of the present invention;  
         [0028]      FIG. 5  is an orthographic projection of the second embodiment of the present invention;  
         [0029]      FIG. 6  is a perspective diagram of the third embodiment of the present invention;  
         [0030]      FIG. 7  is an orthographic projection of the third embodiment of the present invention;  
         [0031]      FIG. 8  is a perspective diagram of the fourth embodiment of the present invention;  
         [0032]      FIG. 9  is an orthographic projection of the fourth embodiment of the present invention;  
         [0033]      FIG. 10  is an exploded perspective diagram of a fixing part 432;  
         [0034]      FIG. 11  is a perspective diagram of the fifth embodiment of the present invention;  
         [0035]      FIG. 12  is an orthographic projection of the fifth embodiment of the present invention; and  
         [0036]      FIGS. 13A, 13B  and  13 C are perspective drawings for explaining a manufacturing method of an antenna apparatus  500 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0037]     In the following, embodiments of the present invention are described with reference to the accompanying drawings.  
         [0038]      FIG. 2  is a perspective diagram of an antenna apparatus  100  according to the first embodiment of the present invention, and  FIG. 3  is an orthographic projection thereof.  
         [0039]     The antenna apparatus  100  of the present embodiment includes a printed wiring board  101 , an antenna unit  102 , and an RF circuit unit  103 .  
         [0040]     The printed wiring board  101  is made from dielectrics such as resin and ceramics, for example, FR-4, and CEM3, on the surface of which electronic parts  111  are mounted. The electronic parts  111  mounted on the printed wiring board  101  are connected by an electrically conductive pattern  112  (illustration omitted), and constitute the RF circuit unit  103 . The RF circuit unit  103  is connected to the antenna unit  102  by a microstrip line  113  formed on the printed wiring board  101 .  
         [0041]     The antenna unit  102  includes a ground plate  121  and the feeding unit  122 .  
         [0042]     The ground plate  121  is constituted by electrically conductive patterns  121   a  and  121   b  formed on the printed wiring board  101 . The electrically conductive patterns  121   a  and  121   b  are connected to a grounding pattern.  
         [0043]     The feeding unit  122  includes a feeding plate  131  and a fixing part  132 . The feeding plate  131  is made by fabricating a metal plate. Here, the shape of the feeding plate  131  is shown as nearly being a circle, which is approximately the same as the conventional cross-section of the feeding units  12  and  22  taken along a plane that contains the center axis of the feeding units  12  and  22 . The feeding plate  131  may be shaped in any form, such as a teardrop and a circle, so long as it can transmit and receive an electric wave of a desired frequency band.  
         [0044]     When the feeding plate  131  is designed for communications at a frequency between 3.1 and 10.6 GHz that is the frequency band of UWB, the angle θ (see  FIG. 5 ) of the periphery section to the centerline C is set at between 40° and 80°, and the height H is set at about 25 mm. Here, the height H is set at approximately λ/4 of the minimum frequency used for transmission and reception. For example, if the frequency between 3.1 and 10.6 GHz should be covered, λ is set at the wavelength corresponding to 3.1 GHz.  
         [0045]     Further, the width W of the ground plate  121  is set up so that ground plate  121  may become slightly greater than the bottom shape of the feeding plate  122  in the width W directions.  
         [0046]     By setting up as described above, the peak value of VSWR can be made smaller than 3.0 in the 3.1-10.6 GHz range that is the frequency band of UWB.  
         [0047]     The fixing part  132  is formed at the lower part of the feeding plate  131 , and at the end in the direction indicated by arrow Z 2  by welding, or by fabricating in one body with the feeding plate  131 . The fixing part  132  has nail sections  132   a  that extend in the arrow Z 2  direction. The nail sections  132   a  are placed into respective through-holes  101  a formed on the printed wiring board  101  at end in the direction indicated by arrow X 2 , are bent onto the rear surface of the printed wiring board  101  in the arrow Z 2  direction, and are fixed to the printed wiring board  101  by soldering. In this manner, the feeding plate  131  is arranged straight up in the arrow Z 1  direction, and fixed to the printed wiring board  101 .  
         [0048]     The fixing part  132  is soldered to the printed wiring board  101  at the end of the microstrip line  113  formed on the printed wiring board  101 . The microstrip line  113  is formed in the directions of the arrows X 1  and X 2  between the electrically conductive patterns  121   a  and  121   b . The other edge of the microstrip line  113  is connected to the RF circuit unit  103 .  
         [0049]     According to this embodiment, the feeding unit  121  is made small and thin as compared with the conventional case where the feeding unit is structured by an inverted cone. Accordingly, the antenna apparatus  100  can be made small and thin.  
         [0050]      FIG. 4  is a perspective diagram of an antenna apparatus  200  according to the second embodiment of the present invention, and  FIG. 5  is an orthographic projection thereof. The same reference numbers are given to the components the same as  FIG. 2  and  FIG. 3 , and the explanation thereof is not repeated.  
         [0051]     The antenna apparatus  200  includes an antenna unit  202  that is different from the antenna unit  102  of the first embodiment. The antenna unit  202  of the second embodiment includes a feeding unit  222  that is different from the feeding unit  122  of the first embodiment.  
         [0052]     The feeding unit  222  of the second embodiment includes a feeding plate  231  that is made into the form where the plane form of the feeding plate  131  (of the first embodiment) is cut at about one-half height H/2.  
         [0053]     Since the height of the feeding plate  231  is about a half of the first embodiment, the feeding unit  202 , and therefore the antenna apparatus  200 , can be made even thinner.  
         [0054]      FIG. 6  is a perspective diagram of an antenna apparatus  300  according to the third embodiment of the present invention, and  FIG. 7  is an orthographic projection thereof. The same reference numbers are given to the components the same as  FIG. 4  and  FIG. 5 , and the explanation thereof is not repeated.  
         [0055]     The antenna apparatus  300  of this embodiment includes an antenna unit  302  that is different from antenna unit  202  of the second embodiment. Further, the antenna unit  302  of this embodiment includes a feeding unit  322  that is different from the feeding unit  222  of the second embodiment.  
         [0056]     The feeding unit  322  of this embodiment include a feeding plate  331  that is arranged not perpendicular to the printed wiring board  101 , but at an angle φ.  
         [0057]     In other words, the feeding plate  331  is arranged inclining to the fixing part  132  at the angle φ.  
         [0058]     According to this embodiment, the height H 2  of the antenna apparatus  300  is lower than the height of the antenna apparatus  200  of the second embodiment by ΔH corresponding to the inclination. In addition, the height ΔH is expressed as follows. 
 
Δ H=H 0/2−{( H/ 2)×sin φ}
 
         [0059]     Therefore, according to this embodiment, the feeding plate  331  is arranged with a lower profile than H 0 /2, and the antenna apparatus  300  can be made further thinner.  
         [0060]      FIG. 8  is a perspective diagram of an antenna apparatus  400  according to the fourth embodiment of the present invention, and  FIG. 9  is an orthographic projection thereof. The same reference numbers are given to the components the same as  FIG. 2  and  FIG. 3 , and the explanation there of is not repeated.  
         [0061]     The antenna apparatus  400  of this embodiment includes an antenna unit  402  is different from the antenna unit  302  of the third embodiment. Further, the antenna unit  402  includes a feeding unit  422  that is different from the feeding unit  322  of the third embodiment. Furthermore, the feeding unit  422  of this embodiment includes a fixing part  432  that is different from fixing part  132  of the third embodiment.  
         [0062]     The fixing part  432  of this embodiment holds the feeding plate  231  such that the feeding plate  231  can be rotated in the directions indicated by arrow φ 11  and arrow φ 12 .  
         [0063]      FIG. 10  is an exploded perspective diagram of the fixing part  432 .  
         [0064]     The fixing part  432  includes a base  441 , a rotation section  442 , and a supporting section  443 .  
         [0065]     The base  441  has nail sections  451  that penetrate the through hole  101   a  of the printed wiring board  101  like the fixing part  132 , and are fixed by soldering. The base  441  has a concavity  452  that is formed approximately in the shape of a hemisphere.  
         [0066]     The rotation section  442  includes a solid sphere section  461  and a feeding plate fixing section  462 . The solid sphere section  461  engages with the concavity  452  of the base  441 .  
         [0067]     The supporting section  443  is formed approximately in the shape of a circular ring. The feeding plate fixing part  462  penetrates a hole  471  of the supporting section  443 . The supporting section  443  is fixed to the base  441  with screws  481 , and the like, such that the solid sphere section  461  of the rotation section  442  is supported rotation-free by the supporting section  443  and the base  441 .  
         [0068]     A feeding plate fixing part  462  is attached to the solid sphere section  461 , and is rotationally moved according to the rotational movement of the solid sphere section  461 . The tip of the feeding plate fixing part  462  is fixed to the feeding plate  231  with a screw  491 .  
         [0069]     In this manner, the feeding plate  231  is supported such that it can be rotationally moved in the directions shown by the arrows φ 11  and φ 12 .  
         [0070]     Since the feeding plate  231  is supported free to rotate as described above, the angle between the feeding plate  231  and the ground plate  121 , and the like, can be adjusted according to the transmission/reception status. That is, by rotationally moving the feeding plate  231  in the directions of φ 11  and φ 12 , alignment between the feeding plate  231  and the ground plate  121  and antenna directivity can be adjusted. Therefore, transmission and reception can be easily optimized.  
         [0071]     In addition, after adjustment, the rotational position of the feeding plate  231  may be fixed by soldering the rotation section  442  to the base  441 , and the like.  
         [0072]      FIG. 11  is a perspective diagram of an antenna apparatus according to the fifth embodiment of the present invention, and  FIG. 12  is an orthographic projection thereof. The same reference numbers are given to the components the same as  FIG. 2  and  FIG. 3 , and the explanation thereof is not repeated.  
         [0073]     The antenna apparatus  500  of this embodiment includes an antenna unit  502  and the RF circuit unit  103  arranged on a flexible printed wiring board  501 .  
         [0074]     The flexible printed wiring board  501  is made of a flexible wiring substrate that can be bent, and mounts the electronic parts  111 . The electronic parts  111  connected by electrically conductive patterns on the flexible printed wiring board  501  constitute the RF circuit unit  103 . The RF circuit unit  103  is connected to the antenna unit  502  by the microstrip line  113  formed on the flexible printed wiring board  501 .  
         [0075]     The antenna unit  502  is constituted by an electrically conductive pattern formed on the flexible printed wiring board  501 , and includes a ground plate  521  and a feeding unit  522 .  
         [0076]     The ground plate  521  is constituted by electrically conductive patterns  521   a  and  521   b . The electrically conductive patterns  521   a  and  521   b  are connected to a grounding pattern.  
         [0077]     The feeding unit  522  is constituted by an electrically conductive pattern  531  (not shown). The conductive pattern  531  serving as the feeding unit  522  is shaped like the cross-sectional form of the solid sphere portion of the conventional feeding unit  22  taken along the plane containing the center axis. In addition, the shape is like the cross-sectional form of the whole feeding unit  22  taken along the plane containing the center.  
         [0078]     When the electrically conductive pattern  531  is designed for communications at a frequency between 3.1 and 10.6 GHz that is the frequency band of UWB, the angle θ of the periphery section to the centerline C is set at between 40° and 80° (see  FIG. 7 ), and the height H 0  is set at about 25 mm. Here, the height H 0  is set at approximately λ/4 of the minimum frequency used for transmission and reception.  
         [0079]     Further, at this time, the width W is set up so that ground plate  521  may become slightly greater than the bottom form of the feeding unit  522 .  
         [0080]     By setting up as described above, the peak value of VSWR can be made smaller than 3.0 in the 3.1-10.6 GHz range that is the frequency band of UWB.  
         [0081]     Next, the manufacturing method of the antenna apparatus  500  of this embodiment is described.  
         [0082]      FIGS. 13A, 13B , and  13 C are perspective drawings for explaining the manufacturing method of the antenna apparatus  500 .  
         [0083]     First, as shown in  FIG. 13A , the electrically conductive patterns  521   a  and  521   b  serving as the ground plate  521 , and the electrically conductive pattern  531  serving as the feeding unit  522 , are formed on the flexible printed wiring board  501 .  
         [0084]     Next, the electronic parts  111  are mounted on the flexible printed wiring board  501  as shown by  FIG. 13B .  
         [0085]     Next, the flexible printed wiring board  501  is bent 90 degrees at the portion indicated by a chain line as shown in  FIG. 13C .  
         [0086]     In this manner, the antenna apparatus  500  as shown in  FIG. 11  and  FIG. 12  is completed.  
         [0087]     According to this embodiment, the feeding unit  522  is made small and thin as compared with the conventional case where the shape of an inverted cone is used. Therefore, the antenna apparatus  500  can be made small and thin.  
         [0088]     By molding the antenna apparatuses  100  through  500  described above by molding resin, the dimensions of the antenna apparatuses  100  through  500  can be further reduced, due to the wavelength compression effect.  
         [0089]     Further, the present invention is not limited to these embodiments, but variations and modifications may be made without departing from the scope of the present invention.  
         [0090]     The present application is based on Japanese Priority Application No. 2004-271580 filed on Sep. 17, 2004 with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.