Patent Publication Number: US-6903691-B2

Title: Surface-mount type antenna and antenna apparatus

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a compact surface-mount type antenna and an antenna apparatus for use in mobile communication equipment such as a cellular phone. 
   2. Description of the Related Art 
   Recently, in keeping with rapid advancement of down-sized, lightweight, and high-performance mobile communication equipment such as a cellular phone, miniaturization and high performance have come to be increasingly demanded of an antenna which constitutes such equipment. To meet such demands, for example, a surface-mount type antenna has hitherto been developed. 
   Now, a surface-mount type antenna of conventional design and an antenna apparatus incorporating the antenna will be described with reference to a perspective view shown in FIG.  7 . 
   In  FIG. 7 , reference numeral  90  represents a surface-mount type antenna. The surface-mount type antenna  90  is mounted on a mounting substrate  96 , thus constituting an antenna apparatus  101 . In the surface-mount type antenna  90  shown in  FIG. 7 , reference numeral  91  represents a substantially rectangular parallelepiped base body;  92  represents a feeding terminal;  93  represents a ground terminal; and  94  represents a radiating electrode. Moreover, in the mounting substrate  96 , reference numeral  97  represents a substrate;  98  represents a feeding electrode;  99  represents a ground electrode; and  100  represents a ground conductor layer. 
   In the conventional surface-mount type antenna  90 , the feeding terminal  92  and the ground terminal  93  are formed on the side surface of the base body  91 . The radiating electrodes  94 , which is routed as a long conductor pattern, is formed so that their ends extend upwardly from the ground terminal  93  on the side surface, is then substantially U-shaped as viewed plane-wise, on the top surface of the base body  91  to form nearly a loop, and extend downwardly from the side surface downwardly toward the feeding terminal  92 . The capacity of the radiating electrode  94  is controlled by providing a part of a vicinity of the feeding terminal  92  of the radiating electrode  94  with a gap  95 , in order to match the impedance with the feeding electrode  98  (feeding line) of the mounting substrate  96 . 
   Meanwhile, in the mounting substrate  96 , on the top surface of the substrate  97  are arranged the feeding electrode  98 , the ground electrode  99 , and the ground conductor layer  100 . The ground conductor layer  100  is arranged face to face with one side of the ground electrode  99  and has connection with the ground electrode  99 . 
   Then, the surface-mount type antenna  90  is mounted on the top surface of the mounting substrate  96 , with the feeding terminal  92  connected to the feeding electrode  98 , and the ground terminal  93  connected to the ground electrode  99 . Thereupon, the antenna apparatus  101  is realized. 
   The related art is disclosed in Japanese Unexamined Patent Publication JP-A 9-162633 (1997). 
   However, the conventional surface-mount type antenna.  90  poses the following problems. By adjusting the size of the gap  95  which is formed in the radiating electrode  94  to achieve impedance matching between the radiating electrode  94  and the feeding electrode  98 , the impedance of the radiating electrode  94  can be changed. Simultaneously, however, the resonant frequency of the antenna varies with the change of the impedance. This makes it difficult to attain the desired antenna characteristics as designed. 
   SUMMARY OF THE INVENTION 
   The invention has been devised in view of the above-described problems with the conventional art, and accordingly its object is to provide a surface-mount type antenna and an antenna apparatus that succeed in readily attaining satisfactory antenna characteristics with stability, in enhancing radiation efficiency, and in achieving miniaturization. 
   The invention provides a surface-mount type antenna comprising: 
   a base body made of a substantially rectangular parallelepiped dielectric or magnetic material; 
   a feeding terminal formed at one end side part of one side surface of the base body; 
   a ground terminal formed at another end side part of one side surface of the base body; and 
   a radiating electrode, to one end of which is connected the ground terminal, disposed such that its other end extends from the other end side part of one side surface, through the other end side part of one principal surface of the base body, to the one end side part of one principal surface, then turns to one side surface so as to extend farther toward the other end side part of one principal surface, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part of one principal surface, 
   wherein the feeding terminal is so disposed as to extend from the one end side part of one side surface to the one end side part of one principal surface, and has its open end arranged in proximity to the radiating electrode. 
   According to the invention, the radiating electrode extends to the one end side part of one principal surface, and then turns to the other end side part, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part of one principal surface. Moreover, the feeding terminal is disposed with its open end located in proximity to the radiating electrode. With this configuration, the radiating electrode can be electromagnetically coupled to the feeding terminal through an electric capacitance generated therebetween. Further, at the time of mounting the antenna on the mounting substrate, since a capacitance can be created between that part of the radiating electrode which extends from the turned portion (bent portion) to the open end and the ground conductor layer of the mounting substrate, the resonant frequency of the radiating electrode can be decreased. This makes it possible to achieve miniaturization of the antenna without increasing the dielectric constant of the base body, and without excessively slenderizing the radiating electrode. 
   According to the invention, the impedance matching between the radiating electrode and the feeding electrode (feeding line) of the mounting substrate on which the radiating electrode is mounted can be achieved by adjusting the capacitance between the radiating electrode and the feeding terminal. Meanwhile, a predominant factor in the magnitude of the resonant frequency of the antenna is the capacitance between that part of the radiating electrode which extends from the turned portion to the open end and the ground conductor layer of the mounting substrate. Hence, variation in the resonant frequency of the antenna, which results from the impedance adjustment achieved by adjusting the capacitance between the radiating electrode and the feeding terminal, can be minimized, whereby making it possible to obtain a compact surface-mount type antenna which offers higher radiation efficiency and stable antenna characteristics. 
   The invention provides a surface-mount type antenna comprising: 
   a base body made of a substantially rectangular parallelepiped dielectric or magnetic material; 
   a feeding terminal formed at one end side part of one side surface of the base body; 
   a ground terminal formed at another end side part of one side surface of the base body; and 
   a radiating electrode, to one end of which is connected the ground terminal, disposed such that its other end extends from the other end side part of one side surface, through the other end side parts of one principal surface and another side surface of the base body, to the one end side part of the other side surface, then turns to one end side part of one principal surface so as to extend farther toward the other end side part of one principal surface, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part of one principal surface, 
   wherein the feeding terminal is so disposed as to extend from the one end side part of one side surface to the one end side part of one principal surface, and has its open end arranged in proximity to the radiating electrode. 
   According to the invention, the radiating electrode extends to the one end side part of one side surface, and then turns to the other end side part, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part of one principal surface. Moreover, the feeding terminal is disposed with its open end located in proximity to the radiating electrode. With this configuration, the radiating electrode can be electromagnetically coupled to the feeding terminal through an electric capacitance generated therebetween. Further, at the time of mounting the antenna on the mounting substrate, since a capacitance can be created between that part of the radiating electrode which extends from the turned portion (bent portion) to the open end and the ground conductor layer of the mounting substrate, the resonant frequency of the radiating electrode can be decreased. This makes it possible to achieve miniaturization of the antenna without increasing the dielectric constant of the base body, and without excessively slenderizing the radiating electrode. 
   According to the invention, the impedance matching between the radiating electrode and the feeding electrode (feeding line) of the mounting substrate on which the radiating electrode is mounted can be achieved by adjusting the capacitance between the radiating electrode and the feeding terminal. Meanwhile, a predominant factor in the magnitude of the resonant frequency of the antenna is the capacitance between that part of the radiating electrode which extends from the turned portion to the open end and the ground conductor layer of the mounting substrate. Hence, variation in the resonant frequency of the antenna, which results from the impedance adjustment achieved by adjusting the capacitance between the radiating electrode and the feeding terminal, can be minimized, whereby making it possible to obtain a compact surface-mount type antenna which offers higher radiation efficiency and stable antenna characteristics. 
   In addition, according to the invention, the radiating electrode extends from the other end of one side surface, through another end side parts of one principal surface and another side surface of the base body, to the one end side part of the other side surface, then turns to one end side part of one principal surface so as to extend farther toward the other end side part of one principal surface. Therefore, the radiating electrode can be made longer, and a compact surface-mount type antenna can be obtained. 
   The invention provides a surface-mount type antenna comprising: 
   a base body made of a substantially rectangular parallelepiped dielectric or magnetic material; 
   a feeding terminal formed at one end side part of one side surface of the base body; 
   a ground terminal formed at another end side part of one side surface of the base body; and 
   a radiating electrode, to one end of which is connected the ground terminal, disposed such that its other end extends from the other end side part of one side surface, through the other end side part of one principal surface of the base body, to the one end side part of one principal surface, then extends to the one end side part of one side surface so as to extend farther toward the other end side part of one side surface, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part of one side surface, 
   wherein the feeding terminal has its open end arranged in proximity to the radiating electrode in the one end side part of one side surface. 
   According to the invention, the radiating electrode extends the one end side part of one side surface, and then turns to the other end side, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part of one side surface. Moreover, the feeding terminal is disposed with its open end located in proximity to the radiating electrode. With this configuration, the radiating electrode can be electromagnetically coupled to the feeding terminal through an electric capacitance generated therebetween. Further, at the time of mounting the antenna on the mounting substrate, since a capacitance can be created between that part of the radiating electrode which extends from the turned portion (bent portion) to the open end and the ground conductor layer of the mounting substrate, the resonant frequency of the radiating electrode can be decreased. This makes it possible to achieve miniaturization of the antenna without increasing the dielectric constant of the base body, and without excessively slenderizing the radiating electrode. 
   According to the invention, the impedance matching between the radiating electrode and the feeding electrode (feeding line) of the mounting substrate on which the radiating electrode is mounted can be achieved by adjusting the capacitance between the radiating electrode and the feeding terminal. Meanwhile, a predominant factor in the magnitude of the resonant frequency of the antenna is the capacitance between that part of the radiating electrode which extends from the turned portion to the open end and the ground conductor layer of the mounting substrate. Hence, variation in the resonant frequency of the antenna, which results from the impedance adjustment achieved by adjusting the capacitance between the radiating electrode and the feeding terminal, can be minimized, whereby making it possible to obtain a compact surface-mount type antenna which offers higher radiation efficiency and stable antenna characteristics. 
   In addition, according to the invention, the radiating electrode extends from the other end side part of one side surface, through the other end side part of one principal surface of the base body, to the one end side part of one principal surface, then extends to the one end side part of one side surface so as to extend farther toward the other end side part of one side surface. Therefore, a distance between the ground conductor layer and the conductor portion from the turned portion to the open end becomes short and a larger capacitance component is obtained, with the result that a compact surface-mount type antenna can be obtained. 
   The invention provides a surface-mount type antenna comprising: 
   a base body made of a substantially rectangular parallelepiped dielectric or magnetic material; 
   a feeding terminal formed at one end side part of one side surface of the base body; 
   a ground terminal formed at another end side part of one side surface of the base body; and 
   a radiating electrode, to one end of which is connected the ground terminal, disposed such that its other end extends from the other end side part of one side surface, through the other end side parts of one principal surface and another side surface of the base body, to the one end side part of the other side surface, then extends through the one end side part of one principal surface to the one end side part of one side surface so as to extend farther toward the other end side part of one side surface, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part of one side surface, 
   wherein the feeding terminal has its open end arranged in proximity to the radiating electrode in the one end side part of one side surface. 
   According to the invention, the radiating electrode extends to the one end side part of one side surface, and then turns to the other end side part, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part of one side surface. Moreover, the feeding terminal is disposed with its open end located in proximity to the radiating electrode. With this configuration, the radiating electrode can be electromagnetically coupled to the feeding terminal through an electric capacitance generated therebetween. Further, at the time of mounting the antenna on the mounting substrate, since a capacitance can be created between that part of the radiating electrode which extends from the turned portion (bent portion) to the open end and the ground conductor layer of the mounting substrate, the resonant frequency of the radiating electrode can be decreased. This makes it possible to achieve miniaturization of the antenna without increasing the dielectric constant of the base body, and without excessively slenderizing the radiating electrode. 
   According to the invention, the impedance matching between the radiating electrode and the feedinglelectrode (feeding line) of the mounting substrate on which the radiating electrode is mounted can be achieved by adjusting the capacitance between the radiating electrode and the feeding terminal. Meanwhile, a predominant factor in the magnitude of the resonant frequency of the antenna is the capacitance between that part of the radiating electrode which extends from the turned portion to the open end and the ground conductor layer of the mounting substrate. Hence, variation in the resonant frequency of the antenna, which results from the impedance adjustment achieved by adjusting the capacitance between the radiating electrode and the feeding terminal, can be minimized, whereby making it possible to obtain a compact surface-mount type antenna which offers higher radiation efficiency and stable antenna characteristics. 
   In addition, according to the invention, the radiating electrode extends from the other end side part of one side surface, through the other end side parts of one principal surface and another side surface of the base body, to the one end side part of the other side surface, then extends through the one end side part of one side surface to the one end side part of one side surface so as to extend farther toward the other end side part of one side surface. Therefore, a distance between the ground conductor layer and the conductor portion from the turned portion to the open end becomes short, with the result that a larger capacitance can be obtained. Further, the radiating electrode can be made longer, therefore a compact surface-mount type antenna can be obtained. 
   In the invention, it is preferable that the length of the radiating electrode between the open end and a turned portion on the one end side part of one principal surface or one side surface is kept in a range of ⅕ to ¾ of the length of one principal surface or one side surface of the base body. 
   According to the invention, when the length of the radiating electrode between the open end and the turned portion on the one end side part of one principal surface or one side surface is kept in a range of ⅕ to ¾ of the length of one principal surface or one side surface of the base body, an antenna which facilitates frequency adjustment can be obtained. 
   In the invention, it is preferable that the base body has a through hole which penetrates all the way through from one end face to the other end face thereof, or a groove formed on another principal surface thereof so as to penetrate all the way through from one end face to the other end face. 
   According to the invention, when the base body has a through hole which penetrates all the way through from one end face to the other end face thereof, or a groove formed on the other principal surface thereof so as to penetrate all the way through from one end face to the other end face, the bandwidth of antenna can be increased. 
   In the invention, it is preferable that the base body is made of a dielectric material having a relative dielectric constant ∈r which is kept within a range from 3 to 30. 
   According to the invention, an effective length of the radiating electrode is decreased, and thus the current distribution region is increased in area. This allows the radiating electrode to emit a larger quantity of radio waves, resulting in advantages in enhancing a gain of the antenna and in achieving miniaturization of the surface-mount type antenna. 
   In the invention, it is preferable that the base body is made of a magnetic material having a relative magnetic permeability μr which is kept within a range from 1 to 8. 
   According to the invention, the radiating electrode has a higher impedance, which results in a low Q factor in the antenna, and the bandwidth is accordingly increased. 
   The invention further provides an antenna apparatus comprising: 
   a mounting substrate having formed thereon a feeding electrode, a ground electrode, and a ground conductor layer which is arranged face to face with one side of the ground electrode and has connection with the ground electrode; and 
   the surface-mount type antenna mentioned above, 
   wherein the antenna apparatus is constructed by mounting the surface-mount type antenna on the mounting substrate, with another principal surface of the base body arranged on the top surface of the mounting substrate face to face with the other side of the ground electrode, and simultaneously connecting the feeding terminal and the ground terminal to the feeding electrode and the ground electrode, respectively. 
   According to the invention, the antenna apparatus is constructed as follows. The surface-mount type antenna of the invention is mounted on the mounting substrate having formed thereon the feeding electrode, the ground electrode, and the ground conductor layer which is arranged face to face with one side of the ground electrode and has connection with the ground electrode. Simultaneously, the feeding terminal and the ground terminal are connected to the feeding electrode and the ground electrode, respectively. Hence, by adjusting the capacitance created between the radiating electrode of the surface-mount type antenna having the turned portion and the feeding electrode, ground electrode, and ground conductor layer of the mounting substrate, impedance matching can be readily achieved between the radiating electrode and the feeding electrode. Moreover, proper setting and adjustment of the resonant frequency and radiation efficiency of the radiating electrode, as well as miniaturization, can also be achieved with ease, whereby making it possible to obtain a compact antenna apparatus which offers higher radiation efficiency and stable antenna characteristics. 
   As described heretofore, according to the invention, it is possible to provide a surface-mount type antenna and an antenna apparatus capable of attaining satisfactory antenna characteristics with stability, of enhancing radiating efficiency, and of achieving miniaturization. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein: 
       FIG. 1A  is a perspective view showing a surface-mount type antenna according to a first embodiment of the invention, and also an antenna apparatus that is constituted by mounting the surface-mount type antenna on a top surface of a mounting substrate according to a first embodiment of the invention; 
       FIG. 1B  is a view showing the surface-mount type antenna according to the first embodiment of the invention, viewed from one side surface side; 
       FIG. 1C  is a view showing the surface-mount type antenna according to the first embodiment of the invention, viewed from one principal surface side; 
       FIG. 1D  is a plan view showing the surface-mount type antenna according to the first embodiment of the invention, and also the antenna apparatus that is constituted by mounting the surface-mount type antenna on a top surface of the mounting substrate according to the first embodiment of the invention; 
       FIG. 2A  is a perspective view showing a surface-mount type antenna according to a second embodiment of the invention, and also an antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of a mounting substrate according to a second embodiment of the invention; 
       FIG. 2B  is a view showing the surface-mount type antenna according to the second embodiment of the invention, viewed from one side surface side; 
       FIG. 2C  is a view showing the surface-mount type antenna according to the second embodiment of the invention, viewed from one principal surface side; 
       FIG. 2D  is a view showing the surface-mount type antenna according to the second embodiment of the invention, viewed from another side surface side; 
       FIG. 2E  is a plan view showing the surface-mount type antenna according to the second embodiment of the invention, and also the antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of the mounting substrate according to the second embodiment of the invention; 
       FIG. 3A  is a perspective view showing a surface-mount type antenna according to a third embodiment of the invention, and also an antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of a mounting substrate according to a third embodiment of the invention; 
       FIG. 3B  is a view showing the surface-mount type antenna according to the third embodiment of the invention, viewed from one side surface side; 
       FIG. 3C  is a view showing the surface-mount type antenna according to the third embodiment of the invention, viewed from one principal surface side; 
       FIG. 3D  is a plan view showing the surface-mount type antenna according to the third embodiment of the invention, and also the antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of the mounting substrate according to the third embodiment of the invention; 
       FIG. 4A  is a perspective view showing a surface-mount type antenna according to a fourth embodiment of the invention, and also an antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of a mounting substrate according to a fourth embodiment of the invention; 
       FIG. 4B  is a view showing the surface-mount type antenna according to the fourth embodiment of the invention, viewed from one side surface side; 
       FIG. 4C  is a view showing the surface-mount type antenna according to the fourth embodiment of the invention, viewed from one principal surface side; 
       FIG. 4D  is a view showing the surface-mount type antenna according to the fourth embodiment of the invention, viewed from another side surface side; 
       FIG. 4E  is a plan view showing the surface-mount type antenna according to the fourth embodiment of the invention, and also the antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of the mounting substrate according to the fourth embodiment of the invention; 
       FIG. 5  is a schematic equivalent circuit diagram for explaining the function of the antenna structure in the surface-mount type antenna and the antenna apparatus embodying the invention; 
       FIGS. 6A and 6B  are perspective views each showing an example of the base-body configuration in the surface-mount type antenna of the invention, with  FIG. 6A  indicating the case of forming a through hole, and  FIG. 6B  indicating the case of forming a groove; and 
       FIG. 7  is a perspective view showing an example of a conventional surface-mount type antenna and an antenna apparatus incorporating the antenna. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Now referring to the drawings, preferred embodiments of the invention are described below. 
   Hereafter, with reference to the accompanying drawings, a description will be given as to a surface-mount type antenna and an antenna apparatus according to an embodiment of the invention. 
     FIG. 1A  is a perspective view showing a surface-mount type antenna according to a first embodiment of the invention, and also an antenna apparatus that is constituted by mounting the surface-mount type antenna on a top surface of a mounting substrate according to a first embodiment of the invention; 
     FIG. 1B  is a view showing the surface-mount type antenna according to the first embodiment of ttle invention, viewed from one side surface side;  FIG. 1C  is a view showing the surface-mount type antenna according to the first embodiment of the invention, viewed from one principal surface side; and  FIG. 1D  is a plan view showing the surface-mount type antenna according to the first embodiment of the invention, and also the antenna apparatus that is constituted by mounting the surface-mount type antenna on a top surface of the mounting substrate according to the first embodiment of the invention. 
   In  FIGS. 1A  to  1 D, a surface-mount type antenna  10  embodying the invention comprises a base body  11 , a feeding terminal  12 , a ground terminal  13  and a radiating electrode  14 . The base body  11  is made of a substantially rectangular parallelepiped dielectric or magnetic material. The feeding terminal  12  is formed at one end side part  11   a  of one side surface a of the base body  11 . The ground terminal  13  is formed at another end side part  11   b  of one side surface a of the base body  11 . The radiating electrode  14  is formed of a line-shaped conductor. The radiating electrode  14 , to one end  14   a  of which is connected the ground terminal  13 , is disposed such that its other end  14   b  extends from the other end part  11   b  of one side surface a of the base body  11 , through the other end side part  11   d  of one principal surface b of the base body  11 , to the one end side part  11   c  of one principal surface b, then turns to one side surface a so as to extend farther toward the other end side part  11   d  of one principal surface b, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part  11   d  of one principal surface b. In addition, in the radiating electrode  14 , a turned portion  15  is formed on the one end side part  11   c  of one principal surface b. The feeding terminal  12  is so disposed as to extend from the one end side part  11   a  of one side surface a to the one end side part  11   c  of one principal surface b, and has its open end  12   a  arranged in proximity to the radiating electrode  14 . 
   Moreover, a mounting substrate  16  comprises a substrate  17 , a feeding electrode  18  formed on the top surface of the substrate  17 , a ground electrode  19 , and a ground conductor layer  20  having connection with the ground electrode  19 . The ground conductor layer  20  is arranged face to face with one side of the ground electrode  19 , that is, in the example shown in  FIGS. 1A  to  1 D, arranged on the left-hand front side of the top surface of the substrate. 
   Then, the surface-mount type antenna  10  according to the first embodiment of the invention is mounted on the mounting substrate  16 , with another principal surface (corresponding to the bottom surface, in the embodiment shown in  FIG. 1A ) of the base body  11  arranged on the top surface of the mounting substrate  16  face to face with the other side of the ground electrode  19  (arranged on the right-hand rear side of the top surface of the substrate, in the embodiment shown in FIG.  1 A). Simultaneously, the feeding terminal  12  and the ground terminal  13  are connected to the feeding electrode  18  and the ground electrode  19 , respectively. Thereupon, an antenna apparatus  21  of the invention is realized. 
   A remarkable feature of the surface-mount type antenna  10  according to the first embodiment of the invention is the configurations of the radiating electrode  14  and the feeding terminal  12 . Specifically, the radiating electrode  14  is formed that its other end extends from the one end side part  11   c  of one principal surface b of the base body  11  to the other end side part  11   d  thereof, thereby creating the turned portion  15 , and is eventually formed into an open end  14   b  near the other end side part  11   d . The length of the radiating electrode  14  between the turned portion  15  and the open end  14   b  is kept in a range of ⅕ to ¾ of the length of the base body  11 . Meanwhile, the feeding terminal  12  has its open end  12   a  opposed to the radiating electrode  14  near the turned portion  15 . 
   Since the turned portion  15  of the radiating electrode  14  faces with the feeding terminal  12  through the base body  11 , the radiating electrode  14  is electromagnetically coupled to the feeding terminal  12  through an electric capacitance generated therebetween. 
   Then, the surface-mount type antenna  10  according to the first embodiment of the invention thus constructed is mounted on the top surface of the mounting substrate  16  at a distance of approximately 0.5 mm to 3 mm, for example, from the end of the ground conductor layer  20 . Simultaneously, the ground terminal  13  is connected via the ground electrode  19  to the ground conductor layer  20 . Thereupon, the antenna apparatus  21  of the invention is operable at a frequency band of approximately 1 GHz to 10 GHz, for example. 
   Note that the radiating electrode  14  acts as a (¼) λ resonator. The longer the radiating electrode  14  in length, the lower the operating frequency. Moreover, the larger the capacitance component between the ground conductor layer  20  and that conductor part of the radiating electrode  14  which extends from the open end  14   b  to the turned portion  15 , the lower the operating frequency. As is practiced in the surface-mount type antenna  21  of the invention, by configuring the radiating electrode  14  in such a way as to make turns over the surfaces of the base body  11 , the base body  11  can be kept small in outer dimension, thus achieving compactness in the antenna. 
     FIG. 2A  is a perspective view showing a surface-mount type antenna according to a second embodiment of the invention, and also an antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of a mounting substrate according to a second embodiment of the invention;  FIG. 2B  is a view showing the surface-mount type antenna according to the second embodiment of the invention, viewed from one side surface side;  FIG. 2C  is a view showing the surface-mount type antenna according to the second embodiment of the invention, viewed from one principal surface side;  FIG. 2D  is a view showing the surface-mount type antenna according to the second embodiment of the invention, viewed from another side surface side; and  FIG. 2E  is a plan view showing the surface-mount type antenna according to the second embodiment of the invention, and also the antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of the mounting substrate according to the second embodiment of the invention. 
   In  FIGS. 2A  to  2 E, a surface-mount type antenna  30  according to a second embodiment of the invention comprises a base body  31 , a feeding terminal  32 , a ground terminal  33 , and a radiating electrode  34  the base body  31  is made of a substantially rectangular parallelepiped dielectric or magnetic material. The feeding terminal  32  is formed at one end side part  31   a  of one side surface a of the base body  31 . The ground terminal  33  is formed at the other end side part  31   b  of one side surface a of the base body  31 . The radiating electrode  34  is formed of a line-shaped conductor. The radiating electrode  34 , to one end  34   a  of which is connected the ground terminal  33 , is disposed such that its other end  34   b  extends from the other end side part  31   b  of one side surface a of the base body  31 , through the other end side parts  31   d ,  31   f  of one principal surface b and another side surface c of the base body  31 , to the one end side part  31   e  of the other side surface c, then turns to one end side part  31   c  of one principal surface b so as to extend farther toward the other end side part  31   d  of one principal surface b, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part  31   d  of one principal surface b. In addition, in the radiating electrode  34 , a turned portion  35  is formed on the one end side part  31   c  of one principal surface b. The feeding terminal  32  is so disposed as to extend from the one end side part  31   a  of one side surface a to the one end side part  31   c  of one principal surface b, and has its open end  32   a  arranged in proximity to the radiating electrode  34 . 
   Moreover, a mounting substrate  36  comprises a substrate  37 , a feeding electrode  38  formed on the top surface of the substrate  37 , a ground electrode  39 , and a ground conductor layer  40  having connection with the ground electrode  39 . The ground conductor layer  40  is arranged face to face with one side of the ground electrode  39 , that is, in the example shown in  FIG. 2A , arranged on the left-hand front side of the top surface of the substrate. 
   Then, the surface-mount type antenna  30  according to the second embodiment of the invention is mounted on the mounting substrate  36 , with the other principal surface (corresponding to the bottom surface, in the embodiment shown in  FIG. 2A ) of the base body  31  arranged on the top, surface of the mounting substrate  36  face to face with the other side of the ground electrode  39  (arranged on the right-hand rear side of the top surface of the substrate, in the embodiment shown in FIG.  2 A). Simultaneously, the feeding terminal  32  and the ground terminal  33  are connected to the feeding electrode  38  and the ground electrode  39 , respectively. Thereupon, an antenna apparatus  41  of the invention is realized. 
   A remarkable feature of the surface-mount type antenna  30  according to the second embodiment of the invention is the configurations of the radiating electrode  34  and the feeding terminal  32 . Specifically, the radiating electrode  34  is formed that its other end extends from the one end side part  31   c  of one principal surface b of the base body  31  to the other end side part  31   d  thereof, thereby creating the turned portion  35 , and is eventually formed into an open end  34   b  near the other end side part  31   d . The length of the radiating electrode  34  between the turned portion  35  and the open end  34   b  is kept in a range of ⅕ to ¾ of the length of the base body  31 . Meanwhile, the feeding terminal  32  has its open end  32   a  opposed to the radiating electrode  34  near the turned portion  35 . 
   In the antenna apparatus  41  of the invention, the surface-mount type antenna  30  according to the second embodiment of the invention is similar in structure to the surface-mount type antenna  10  according to the first embodiment of the invention shown in  FIGS. 1A  to  1 D, but the difference is that the radiating electrode  34  is so formed as to extend across the other side surface c. Just as is the case with the antenna apparatus  21  of the invention, the surface-mount type antenna  30  according to the second embodiment of the invention is mounted on the top surface of the mounting substrate  36  at a distance of approximately 0.5 mm to 3 mm, for example, from the end of the ground conductor layer  40 . Simultaneously, the ground terminal  33  is connected via the ground electrode  39  to the ground conductor layer  40 . Thereupon, the antenna apparatus  41  is operable at a frequency band of approximately 1 GHz to 10 GHz, for example. 
   In this way, by configuring the radiating electrode  34  so as to extend across the other side surface c, the radiating electrode  34  can be made longer, and correspondingly the operating frequency is decreased. This does away with the need for making the base body  31  larger in outer dimension, thus achieving compactness in the antenna. 
     FIG. 3A  is a perspective view showing a surface-mount type antenna according to a third embodiment of the invention, and also an antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of a mounting substrate according to a third embodiment of the invention;  FIG. 3B  is a view showing the surface-mount type antenna according to the third embodiment of the invention, viewed from one side surface side;  FIG. 3C  is a view showing the surface-mount type antenna according to the third embodiment of the invention, viewed from one principal surface side; and  FIG. 3D  is a plan view showing the surface-mount type antenna according to the third embodiment of the invention, and also the antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of the mounting substrate according to the third embodiment of the invention. 
   In  FIGS. 3A  to  3 D, a surface-mount type antenna  50  according to a third embodiment of the invention comprises a base body  51 , a feeding terminal  52 , a ground terminal  53 , and a radiating electrode  54 . The base body  51  is made of a substantially rectangular parallelepiped dielectric or magnetic material. The feeding terminal is formed at one end side part  51   a  of one side surface a of the base body  51 . The ground terminal is formed at another end side part  51   b  of one side surface a of the base body  51 . The radiating electrode  54  is formed of a line-shaped conductor. The radiating electrode  34 , to one end  54   a  of which is connected the ground terminal, is disposed such that its other end  54   b  extends from the other end side part  5   b  of one side surface a, through the other end side part  51   d  of one principal surface b of the base body  51 , to the one end side part  51   c  of one principal surface b, then extends to the one end side part  51   a  of one side surface a so as to extend farther toward the other end side part  51   b  of one side surface a, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part  51   b  of one side surface a. In addition, in the radiating electrode  54 , a turned portion  55  is formed on the one end side part  51   a  of one side surface a. The feeding terminal  52  has its open end  52   a  arranged in proximity to the radiating electrode  54  in the one end side part  51   a  of one side surface a. 
   Moreover, a mounting substrate  56  comprises a substrate  57 , a feeding electrode  58  formed on the top surface of the substrate  57 , a ground electrode  59 , and a ground conductor layer  60  having connection with the ground electrode  59 . The ground conductor layer  60  is arranged face to face with one side of the ground electrode  59 , that is, in the example shown in  FIG. 3A , arranged on the left-hand front side of the top surface of the substrate. 
   Then, the surface-mount type antenna  50  according to the third embodiment of the invention is mounted on the mounting substrate  56 , with the other principal surface (corresponding to the bottom surface, in the embodiment shown in  FIG. 3A ) of the base body  51  arranged on the top surface of the mounting substrate  56  face to face with the other side of the ground electrode  59  (arranged on the right-hand rear side of the top surface of the substrate, in the embodiment shown in FIG.  3 A). Simultaneously, the feeding terminal  52  and the ground terminal  53  are connected to the feeding electrode  58  and the ground electrode  59 , respectively. Thereupon, an antenna apparatus  61  of the invention is realized. 
   A remarkable feature of the surface-mount type antenna  50  according to the third embodiment of the invention is the configurations of the radiating electrode  54  and the feeding terminal  52 . Specifically, the radiating electrode  54  is formed such that its other end extends from one end side part  51   a  of one side surface a of the base body  51  to the other end side part  51   b  thereof, thereby creating the turned portion  55 , and is eventually formed into an open end. The length of the radiating electrode  54  between the turned portion  55  and the open end is kept in a range of ⅕ to ¾ of the length of the base body  51 . Meanwhile, the feeding terminal  52  has its open end  52   b  opposed to the radiating electrode  54  near the turned portion  55 . 
   In the antenna apparatus  61  of the invention, the surface-mount type antenna  50  according to the third embodiment of the invention is similar in structure to the surface-mount type antenna  10  according to the first embodiment of the invention shown in  FIGS. 1A  to  1 D, but the difference is that both the turned portion  55  and the open end  54   b  are formed on one side surface a. Just as is the case with the antenna apparatus  21  of the invention, the surface-mount type antenna  50  according to the third embodiment of the invention is mounted on the top surface of the mounting substrate  56  at a distance of approximately 0.5 mm to 3 mm, for example, from the end of the ground conductor layer  60 . Simultaneously, the ground terminal  53  is connected via the ground electrode  59  to the ground conductor layer  60 . Thereupon, the antenna apparatus  61  is operable at a frequency band of approximately 1 GHz to 10 GHz, for example. 
   In this way, by forming both the turned portion  55  and the open end  54   b  on one side surface a, the interval between the ground conductor layer  60  and that conductor part of the radiating electrode  54  which extends from the turned portion  55  to the open end  54   b  can be made shorter; wherefore a larger capacitance component can be created and correspondingly the operating frequency is decreased. This does away with the need for making the base body  51  larger in outer dimension, thus achieving compactness in the antenna. 
     FIG. 4A  is a perspective view showing a surface-mount type antenna according to a fourth embodiment of the invention, and also an antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of a mounting substrate according to a fourth embodiment of the invention;  FIG. 4B  is a view showing the surface-mount type antenna according to the fourth embodiment of the invention, viewed from one side surface side;  FIG. 4C  is a view showing the surface-mount type antenna according to the fourth embodiment of the invention, viewed from one principal surface side;  FIG. 4D  is a view showing the surface-mount type antenna according to the fourth embodiment of the invention, viewed from another side surface side; and  FIG. 4E  is a plan view showing the surface-mount type antenna according to the fourth embodiment of the invention, and also the antenna apparatus that is constituted by mounting the surface-mount type antenna on the top surface of the mounting substrate according to the fourth embodiment of the invention. 
   In  FIGS. 4A  to  4 E, a surface-mount type antenna  70  according to a fourth embodiment of the invention comprises a base body  71 , a feeding terminal  72 , a ground terminal  73 , and a radiating electrode  74 . The base body  71  is made of a substantially rectangular parallelepiped dielectric or magnetic material. The feeding terminal  72  is formed at one end side part  71   a  of one side surface a of the base body  71 . The ground terminal  73  is formed at the other end side part  71   b  of one side surface a. The radiating electrode  74  is formed of a line-shaped conductor. The radiating electrode  74 , to one end  74   a  of which is connected the ground terminal  73 , is disposed such that its other end extends from the other end side part  71   b  of one side surface a of the base body  71 , through the other end side parts  71   d ,  71   f  of one principal surface b and the other side surface c of the base body  71 , to the one end side part  71   e  of the other side surface c, then extends through the one end side part  71   c  of one principal surface b to the one end side part  71   a  of one side surface a so as to extend farther toward the other end side part  71   b  of one side surface a, and is eventually formed into an open end facing substantially perpendicularly with a midpoint of the other end side part  71   b  of one side surface a. In addition, in the radiating electrode  74 , a turned portion  75  is formed on the one end side part  71   a  of one side surface a. The feeding terminal  72  has its open end  72   a  arranged in proximity to the radiating electrode  74  in the one end side part  71   a  of one side surface a. 
   Moreover, a mounting substrate  76  comprises a substrate  77 , a feeding electrode  78  formed on the top surface of the substrate  77 , a ground electrode  79 , and a ground conductor layer  80  having connection with the ground electrode  79 . The ground conductor layer  80  is arranged face to face with one side of the ground electrode  79 , that is, in the example shown in  FIG. 4A , arranged on the left-hand front side of the top surface of the substrate. 
   Then, the surface-mount type antenna  70  according to the fourth embodiment of the invention is mounted on the mounting substrate  76 , with the other principal surface. (corresponding to the bottom surface, in the embodiment shown in  FIG. 4A ) of the base body  71  arranged on the top surface of the mounting substrate  76  face to face with the other side of the ground electrode  79  (arranged on the right-hand rear side of the top surface of the substrate, in the embodiment shown in FIG.  4 A). Simultaneously, the feeding terminal  72  and the ground terminal  73  are connected to the feeding electrode  78  and the ground electrode  79 , respectively. Thereupon, an antenna apparatus  81  of the invention is realized. 
   A remarkable feature of the surface-mount type antenna  70  according to the fourth embodiment of the invention is the configurations of the radiating electrode  74  and the feeding terminal  72 . Specifically, the radiating electrode  74  is formed such that its other end extends from one end side part  71   a  of one side surface a of the base body  71  to the other end side part  71   b  thereof, thereby creating the turned portion  75 , and is eventually formed into an open end. The length of the radiating electrode  74  between the turned portion  75  and the open end is kept in a range of ⅕ to ¾ of the length of the base body  71 . Meanwhile, the feeding terminal  72  has its open end  72   b  opposed to the radiating electrode  74  near the turned portion  75 . 
   In the antenna apparatus  81  of the invention, the surface-mount type antenna  70  according to the fourth embodiment of the invention is similar in structure to the surface-mount type antenna  10  according to the first embodiment of the invention shown in  FIGS. 1A  to D, but the difference is that the radiating electrode  74  is so formed as to extend across the other side surface c, and both the turned portion  75  and the open end  74   b  are formed on one side surface a. Just as is the case with the antenna apparatus  21  of the invention, the surface-mount type antenna  70  according to the fourth embodiment of the invention is mounted on the top surface of the mounting substrate  76  at a distance of approximately 0.5 mm to 3 mm, for example, from the end of the ground conductor layer  80 . Simultaneously, the ground terminal  73  is connected via the ground electrode  79  to the ground conductor layer  80 . Thereupon, the antenna apparatus  81  is operable at a frequency band of approximately 1 GHz to 10 GHz, for example. 
   In this way, by configuring the radiating electrode  74  so as to extend across the other side surface c, as well as by forming both the turned portion  75  and the open end  74   b  on one side surface a, the interval between the ground conductor layer  80  and that conductor part of the radiating electrode  74  which extends from the turned portion  75  to the open end  74   b  can be made shorter; wherefore a larger capacitance component can be created. Moreover, the radiating electrode  74  can be made longer, and correspondingly the operating frequency is decreased. This does away with the need for making the base body  71  larger in outer dimension, thus achieving compactness in the antenna. 
   With reference to the schematic equivalent circuit diagram shown in  FIG. 5 , a description will be given below as to the function of the antenna structure in the surface-mount type antenna  10 ,  30 ,  50 ,  70  according to the first to fourth embodiments of the invention and the antenna apparatus  21 ,  41 ,  61 ,  81  employing the same. 
   In  FIG. 5 , reference symbol L 1  denotes an inductance of the radiating electrode  14 ,  34 ,  54 ,  74  extending from the ground conductor layer  20 ,  40 ,  60 ,  80 , through the ground electrode  19 ,  39 ,  59 ,  79  and the ground terminal  13 ,  33 ,  53 ,  73 , to the surfaces of the base body  11 ,  31 ,  51 ,  71 ; C 2  denotes a capacitance generated between the ground conductor layer  20 ,  40 ,  60 ,  80  and that part of the radiating electrode  14 ,  34 ,  54 ,  74  which extends from the turned portion  15 ,  35 ,  55 ,  75  to the open end  14   b ,  34   b ,  54   b  and  74   b ; and C 1  denotes a capacitance generated mainly between the turned portion  15 ,  35 ,  55 ,  75  of the radiating electrode  14 ,  34 ,  54 ,  74  and the feeding terminal  12 ,  32 ,  52 ,  72 . Note that between the capacitance C 1  and the ground is connected a high-frequency signal power supply, and that the equivalent circuit further includes radiation resistance (not shown) of the radiating electrode  14 ,  34 ,  54 ,  74 . The radiating electrode  14 ,  34 ,  54 ,  74 , which extends from the ground conductor layer  20 ,  40 ,  60 ,  80 , through the ground electrode  19 ,  39 ,  59 ,  79  and the ground terminal  13 ,  33 ,  53 ,  73 , to the surfaces of the base body  11 ,  31 ,  51 ,  71 , has the turned portion  15 ,  35 ,  55 ,  75 . Here, a capacitance generated between the turned portion  15 ,  35 ,  55 ,  75  and the ground conductor layer  20 ,  40 ,  60 ,  80  can be ignored, because the current flowing nearby is so large that the inductance component becomes predominant. Further, the inductance as observed in that part of the radiating electrode  14 ,  34 ,  54 ,  74  which extends from the turned portion  15 ,  35 ,  55 ,  75  to the open end can also be ignored, because the current flowing toward the open end  14   b ,  34   b ,  54   b  and  74   b  is so small that the capacitance component becomes predominant. 
   The operating frequency of the surface-mount type antenna  10 ,  30 ,  50 ,  70  of the invention can be controlled by adjusting the inductance L 1  of the radiating electrode  14 ,  34 ,  54 ,  74  and the capacitance C 2 . Moreover, by adding the capacitance C 2 , the resonant frequency of the antenna can be decreased. This makes it possible to achieve miniaturization of the antenna without increasing the dielectric constant of the base body, and without excessively slenderizing the radiating electrode. 
   Here, the capacitance C 2  generated between the ground conductor layer  20 ,  40 ,  60 ,  80  and that part of the radiating electrode which extends from the turned portion  15 ,  35 ,  55 ,  75  to the open end  14   b ,  34   b ,  54   b  and  74   b  is roughly proportional to the length of the radiating electrode between the turned portion and the open end. Hence, making adjustment to the length of the radiating electrode between the turned portion and the open end helps facilitate frequency adjustment to the antenna. 
   It is preferable that the length of the radiating electrode between the turned portion  15 ,  35 ,  55 ,  75  and the open end  14   b ,  34   b ,  54   b  and  74   b  is kept in a range of ⅕ to ¾ of the length of the base body  11 ,  31 ,  51 ,  71 . In this case, at the time of making frequency adjustment on the basis of the length of the radiating electrode between the open end  14   b ,  34   b ,  54   b  and  74   b  and the turned portion  15 ,  35 ,  55 ,  75 , the relationship between the length of the radiating electrode between the open end  14   b ,  34   b ,  54   b  and  14   b  and the turned portion  15 ,  35 ,  55 ,  75  and the resonant frequency of the antenna assumes linearity. Hence, it is possible to realize an antenna that offers satisfactory frequency adjustability. If the length of the radiating electrode between the turned portion  15 ,  35 ,  55 ,  75  and the open end  14   b ,  34   b ,  54   b  and  74   b  is less than ⅕ of the length of the base body, the length of the radiating electrode between the open end  14   b ,  34   b ,  54   b  and  74   b  to the turned portion  15 ,  35 ,  55 ,  75  is so short that the resonant frequency is undesirably limited in its range of adjustment. By contrast, if the length of the radiating electrode between the turned portion  15 ,  35 ,  55 ,  75  to the open end  14   b ,  34   b ,  54   b  and  74   b  is greater than ¾ of the length of the base body, a needless capacitance component is undesirably created between the open end  14   b ,  34   b ,  54   b  and  74   b  and a midpoint of the other end side part of the radiating electrode  14 ,  34 ,  54 ,  74 . 
   Meanwhile, the capacitance C 1  can be set at an appropriate value by adjusting the interval of the gap between the turned portion  15 ,  35 ,  55 ,  75  and the feeding terminal  12 ,  32 ,  52 ,  72 . 
   In the surface-mount type antenna  10 ,  30 ,  50 , and  70  according to the first to fourth embodiments of the invention, the capacitance C 1  existing between the turned portion  15 ,  35 ,  55 ,  75  of the radiating electrode  14 ,  34 ,  54 ,  74  and the feeding terminal  12 ,  32 ,  52 ,  72  is created to achieve impedance adjustment so that the radiating electrode  14 ,  34 ,  54 ,  74  can be excited efficiently. To achieve impedance adjustment so that the radiating electrode  14 ,  34 ,  54 ,  74  can be excited efficiently, the capacitance C 1  should preferably be changed by varying the interval between the turned portion  15 ,  35 ,  55 ,  75  and the feeding terminal  12 .,  32 ,  0 . 52 ,  72 . 
   At this time, since the capacitance C 1  and the impedance of the feeding line are higher relative to the capacitance C 2 , the resonant frequency of the antenna is dependent mainly on the values for the capacitance C 2  and the inductance L 1 . Thus, it never occurs that the resonant frequency of the antenna is varied greatly with the change of the capacitance C 1 . As a result, according to the surface-mount type antenna  10 ,  30 ,  50 , and  70  and the antenna apparatus  21 ,  41 ,  61 , and  81  according to the first to fourth embodiments of the invention, not only it is possible to achieve miniaturization, but it is also possible to attain the desired antenna characteristics as designed. 
   In the surface-mount type antenna  10 ,  30 ,  50 , and  70  according to the first to fourth embodiments of the invention, the base body  11 ,  31 ,  51 ,  71  is made of a substantially rectangular parallelepiped dielectric or magnetic material. For example, there is prepared a dielectric material which is predominantly composed of alumina (relative dielectric constant: 9.6). The dielectric material in powder form is subjected to pressure-molding and firing to obtain ceramics. Using the ceramics, the base body is fabricated. In the alternative, the base body  11 ,  31 ,  51 ,  71 , may be composed of a composite material made of ceramics, i.e. a dielectric material, and resin, or composed of a magnetic material such as ferrite. 
   In a case where the base body  11 ,  31 ,  51 ,  71  is composed of a dielectric material, a high frequency signal propagates through the radiating electrode  14 ,  34 ,  54 ,  74  at a lower speed, resulting in the wavelength becoming shorter. When the relative dielectric constant of the base body  11 ,  31 ,  51 ,  71  is expressed as ∈r, the effective length of the conductor pattern of the radiating electrode  14 ,  34 ,  54 ,  74  is reduced to a value: (1/∈r) 1/2 . Hence, where the pattern length is kept the same, as the relative dielectric constant of the base body  11 ,  31 ,  51 ,  71  is increased, the current distribution region becomes larger and larger in area. This allows the radiating electrode  14 ,  34 ,  54 ,  74  to emit a larger quantity of radio waves, resulting in an advantage in enhancing the gain of the antenna. 
   Meanwhile, in the case of attaining the same antenna characteristics as conventional ones, the pattern length of the radiating electrode  14 ,  34 ,  54 ,  74  can be given as (1/∈r) 1/2 , thus making the surface-mount type antenna  10 ,  30 ,  50 , and  70  according to the first to fourth embodiments of the invention compact. 
   Note that fabricating the base body  11 ,  31 ,  51 ,  71  using a dielectric material poses the following tendencies. If the value ∈r is less than 3, it approaches the relative dielectric constant as observed in the air (∈r=1). This makes it difficult to meet the demand of the market for antenna miniaturization. By contrast, if the value ∈r exceeds 30, although miniaturization can be achieved, since the gain and the bandwidth of the antenna are proportional to the size of the antenna, the gain and the bandwidth of the antenna are sharply decreased. As a result, the antenna fails to offer satisfactory antenna characteristics. Hence, in the case of fabricating the base body  11 ,  31 ,  51 ,  71  using a dielectric material, it is preferable to use a dielectric material having a relative dielectric constant ∈r which is kept within a range from 3 to 30. The preferred examples of such a dielectric material include ceramic materials typified by alumina ceramics, zirconia ceramics, etc; and resin materials typified by tetrafluoroethylene, glass epoxy, etc. 
   On the other hand, in the case of fabricating the base body  11 ,  31 ,  51 ,  71  using a magnetic material, the radiating electrode  14 ,  34 ,  54 ,  74  has a higher impedance. Thus, the Q factor of the antenna becomes lower, and correspondingly the bandwidth can be increased. 
   Fabricating the base body  11 ,  31 ,  51 ,  71  using a magnetic material poses the following tendency. If the relative magnetic permeability μr exceeds 8, although a wider bandwidth can be achieved in the antenna, since the gain and the bandwidth of the antenna are proportional to the size of the antenna, the gain and the bandwidth of the antenna are sharply decreased. As a result, the antenna fails to offer satisfactory antenna characteristics. Hence, in the case of fabricating the base body  11 ,  31 ,  51 ,  71  using a magnetic material, it is preferable to use a magnetic material having a relative magnetic permeability μr which is kept within a range from 1 to 8. The preferred examples of such a magnetic material include YIG (Yttria Iron Garnet), Ni—Zr compound, and Ni—Co—Fe compound. 
   In the surface-mount type antenna  10 ,  30 ,  50 , and  70  according to the first to fourth embodiments of the invention, it is preferable that the base body  11 ,  31 ,  51 ,  71  has a through hole drilled all the way through from one end face to the other end face, or a groove formed on the other principal surface of the base body  11 ,  31 ,  51 ,  71  so as to penetrate all the way through from one end face to the other end face. In this case, the effective relative dielectric constant of the base body  11 ,  31 ,  51 ,  71  can be decreased; wherefore the accumulation of electrolytic energy can be suppressed. This makes it possible to achieve a wider bandwidth in the surface-mount type antenna  10 ,  30 ,  50 , and  70  according to the first to fourth embodiments of the invention. 
     FIGS. 6A and 6B  are perspective views each showing an example of the base-body configuration. In  FIG. 6A , the base body  110 , a through hole  111  is formed so as to penetrate all the way through from one end face to the other end face in a longitudinal direction of the base body  110 . In  FIG. 6B , in the base body  112 , a groove  113  is formed on the other principal surface d of the base body  112  so as to penetrate all the way through from one end face to the other end face in a longitudinal direction of the base body  112 . 
   The radiating electrode  14 ,  34 ,  54 ,  74 , the turned portion  15 ,  35 ,  55 ,  75 , the feeding terminal  12 ,  32 ,  52 ,  72  and the ground terminal  13 ,  33 ,  53 ,  73  are each made of for example a metal material which is predominantly composed of one selected from the group consisting of aluminum, copper, nickel, silver, palladium, platinum, and gold. In order to form various patterns using the aforementioned metal materials, conductor layers having desired pattern configurations are formed on the surface of the base body  11 ,  31 ,  51 ,  71  by means of a conventionally-known printing method, a thin-film forming technique based on a vapor-deposition method, a sputtering method, etc., a metal foil bonding method, plating method, or the like. 
   As the substrate  17 ,  37 ,  57 ,  77  constituting the mounting substrate  16 ,  36 ,  56 ,  76 , an ordinary circuit substrate made of for example glass epoxy or alumina ceramics is employed. 
   Moreover, the feeding electrode  18 ,  38 ,  58 ,  78  and the ground electrode  19 ,  39 ,  59 ,  79  are each composed of a conductor which is employed in an ordinary circuit substrate, such as copper or silver. 
   The ground conductor layer  20 ,  40 ,  60 ,  80 , which is arranged on the top surface of the mounting substrate  16 ,  36 ,  56 ,  76  face to face with one side of the ground electrode  19 ,  39 ,  59 ,  79 , is preferably composed of a conductor material such as copper or silver which is commonly employed in an ordinary circuit board. Moreover, the antenna is preferably mounted so as to protrude from the edge of the ground conductor layer  20 ,  40 ,  60 ,  80 . This is desirable in terms of enhancement of the bandwidth and gain of the antenna. 
   Note that mounting of the surface-mount type antenna  10 ,  30 ,  50 ,  70  on the top surface of the mounting substrate  16 ,  36 ,  56 ,  76 , as well as connecting the feeding terminal  12 ,  32 ,  52 ,  72  and the ground terminal  13 ,  33 ,  53 ,  73  to the feeding electrode  18 ,  38 ,  58 ,  78  and the ground electrode  19 ,  39 ,  59 ,  79 , respectively, is preferably achieved by means of soldering through a reflow furnace, for example. 
   (Working Example) 
   Next, a description will be given as to a practical example of the surface-mount type antenna and the antenna apparatus according to the first embodiment of the invention. The example is built as a 1.575 GHz-band antenna designed for GPS. 
   In an ordinary quarter-wavelength monopole antenna, the length of its antenna element is set at 47 mm. Meanwhile, the surface-mount type antenna  10  according to the fist embodiment of the invention shown in  FIGS. 1A  to  1 D is constructed as follows. Firstly, there is prepared an alumina-made base body (dimension: 10 mm×4 mm×3 mm). Then, like the radiating electrode  14  shown in  FIGS. 1A  to  1 D, a 1 mm-wide conductor pattern is formed thereon using a silver conductor. Next, the turned portion  15  is created. The length of the radiating electrode  14  between the turned portion  15  and the open end  14   b  is set at 3 mm. Thereby, the resonant frequency of the surface-mount type antenna  10  according to the first embodiment is adjusted properly. 
   As the mounting substrate  16 , a 0.8 mm-thick glass epoxy substrate is used. The ground conductor layer  20  has the size of 40 mm×80 mm. The antenna apparatus  21  according to the first embodiment of the invention is characterized by the center frequency of 1.575 GHz and the bandwidth of 35 MHz. 
   It is to be understood that the application of the invention is not limited to the specific embodiments described heretofore, and that many modifications and variations of the invention are possible within the spirit and scope of the invention. 
   The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.