in fig1 one embodiment of a surface - mounting type antenna of the present invention is shown . in fig1 the surface - mounting type antenna 40 is composed of some electrodes disposed on the surface of a base member 41 in the form of a rectangular solid made up of a dielectric substance such as ceramics , resin , etc . as one insulating material . first of all , on the substantially whole surface of a first major surface 41 a of the base member 41 a grounding electrode 42 is disposed . further , on a second major surface 41 b of the base member 41 a strip - like radiation electrode 43 is disposed along the long side of the base member 41 . at a first end of the radiation electrode 43 an open - ended terminal 43 a is disposed , and a second end is connected to a connecting terminal 44 disposed over an side surface 41 c of the base member 41 to the first major surface 41 a . more , the connecting terminal 44 and the grounding electrode 42 are insulated from each other . further , on the second major surface 41 b of the base member 41 a power - supply electrode 45 located in the vicinity of the open - ended terminal 43 a of the radiation electrode 43 is disposed , and the power - supply electrode 45 is connected to a power - supply terminal 46 disposed over the side surface 41 d to the first major surface 41 a of the base member 41 . next , in fig2 an antenna device of the present invention is shown . in fig2 to the same or equivalent portions as in fig1 and 10 the same reference numerals are given and their explanation is omitted . in the antenna device 50 shown in fig2 the surface - mounting type antenna 40 is mostly mounted on the circuit - board grounding electrode 3 in the vicinity of a corner portion of the circuit board 2 . the surface - mounting type antenna 40 is arranged so as to direct the portion having the connecting terminal 44 formed , of the base member 41 toward the comer portion of the circuit board 2 and to direct the portion having an open - ended terminal 43 a , of the radiation electrode 43 in the direction of being separated from the corner portion on the side edge of the circuit board 2 . the grounding electrode 42 and power - supply terminal 46 of the surface - mounting type antenna 40 are connected to the circuit - board grounding electrode 3 and power - supply line 4 disposed on the circuit board 2 respectively . and the connecting terminal 44 of the surface - mounting type antenna 40 is connected by soldering , etc . to an external connecting electrode 51 formed in an area 2 a having no circuit - board grounding electrode disposed on the circuit board 2 , and the external connecting electrode 51 is connected to the circuit - board grounding electrode 3 through a linear pattern 52 as an inductance circuit . here , in fig3 an equivalent circuit of the antenna device 50 in fig2 is shown . in fig3 to the same or equivalent portions as in fig1 the same reference numerals are given and their explanation is omitted . in fig3 the inductance l 2 and resistance r 2 represent an inductance component and resistance component of the linear pattern 52 disposed on the circuit board 2 . further , one end of a resistor r 1 is not directly grounded , and is grounded through the inductance l 2 and resistance r 2 in succession . and the resonance frequency of the antenna device 50 is determined mainly by the inductance l 1 and l 2 , and capacitance c 2 . in this way , in the antenna device 50 of the present invention , because the second end of the radiation electrode 43 of the surface - mounting type antenna 40 is grounded through the connecting terminal 44 and linear pattern 52 , the real inductance component of the antenna as a whole is increased and the resonance frequency is reduced . in the converse way , this means that if the frequency as a target is the same , the inductance l 1 of the radiation electrode 43 is able to be reduced as much as the increase of inductance l 2 by the linear pattern 52 . and the fact that the inductance l 1 of the radiation electrode 43 is able to be reduced leads to the possibility of a shorter radiation electrode 43 , that is , a smaller - sized surface - mounting type antenna 40 by making the base member 41 shorter . in this way , in the antenna device 50 of the present invention , by shortening the length of the surface - mounting type antenna 40 to be mounted , a linear pattern 52 is able to be formed in the area occupied by the shortened portion on the circuit board 2 . as the linear pattern 52 has little height in comparison with the surface - mounting type antenna 40 , the occupied volume by an antenna device including the surface - mounting type antenna 40 and linear pattern 52 is able to be made smaller than in the case of the conventional surface - mounting type antenna 10 mounted on the circuit board 2 . further , because the portion in which the linear pattern 52 is formed corresponds to a corner portion on the circuit board 2 , no parts are mounted at the corner portion . because of this , the thickness of the circuit board 2 including the mounted parts is made thin at the comer portion . then , there is a merit of the increased freedom of designing in such a way that a cover of the circuit board 2 is able to be made matched to the circuit board 2 by rounding a part of the cover corresponding to the corner portion of the circuit board 2 . further , according to an antenna device 50 of the present invention , the bandwidth as an antenna is able to be widened , and the gain is also able to be increased . according to the experiment conducted by the inventors of the application concerned , in the case of the conventional antenna device , if the dimension of a surface - mounting type antenna is 15 mm × 3 mm × 1 . 8 mm , the occupied space becomes 81 cubic millimeters . on the other hand , in the case of the antenna device of the present invention , if the dimension of a surface - mounting type antenna is 12 mm × 3 mm × 1 . 8 mm , the occupied space was able to be made 64 . 8 cubic millimeters . as a result , according to an antenna device of the present invention , the occupied space of the antenna device as a whole was able to be reduced to about 80 %. further , in the conventional antenna device , the bandwidth of the antenna was 24 . 0 mhz , and the maximum antenna gain was − 2 . 7 dbd and the average gain − 4 . 6 dbd . however , in the antenna device of the present invention , the bandwidth of the antenna was expanded to 24 . 1 mhz , and the maximum antenna gain became − 2 . 1 dbd and the average gain − 3 . 8 dbd , which means an extensive improvement . further , according to the antenna device 50 of the present invention , because the inductance l 2 of the linear pattern 52 formed on the circuit board 2 is able to be designed independently of the surface - mounting type antenna 40 , after the surface - mounting type antenna 40 has been designed so as to give the best capacitance c 2 and conductance g , it is possible to independently determine the inductance l 2 for deciding the resonance frequency by designing the length and shape of the linear pattern 52 . thus , it is possible to extend the freedom of designing antenna devices . further , the antenna device 50 of the present invention is disposed in the vicinity of a corner portion of the circuit board so as to direct the portion having a connecting terminal formed , of the base member toward a corner portion of the circuit board and to direct the portion having an open - ended terminal of the radiation electrode formed in the direction of being separated from a comer portion on the side edge , of the circuit board . by arranging the surface - mounting type antenna 40 on the circuit board 2 in this way , the gain is able to be further increased . according to the experiment by the inventors of the application concerned , when the direction of the surface - mounting type antenna is reversed , the maximum antenna gain becomes − 9 . 6 dbd and this is greatly deteriorated in comparison with the former gain of − 2 . 1 dbd . thus , by the surface - mounting type antenna arranged so as to direct the portion having a connecting terminal formed , of the base member toward a corner portion of the circuit board and to direct the portion having an open - ended terminal of the radiation electrode formed in the direction of being separated from a corner portion on the side edge , of the circuit board , the improvement of the antenna gain was able to be confirmed . in fig4 another embodiment of an antenna device of the present invention is shown . in fig4 to the same or equivalent portions as in fig2 , and 13 the same reference numerals are given and their explanation is omitted . in the antenna device 60 shown in fig4 the grounding terminal 33 of the surface - mounting type antenna 30 is not directly connected to the circuit - board grounding electrode 3 of the circuit board 2 , but connected by soldering , etc . to an external connecting electrode 51 formed in the area 2 a not having the circuit - board grounding electrode 3 formed on the circuit board 2 , and the external connecting electrode 51 is connected to the circuit - board grounding electrode 3 through the linear pattern 52 as an inductance circuit . that is , the grounding terminal 33 of the surface - mounting type antenna 30 is used with the same purpose as the connecting terminal 44 of the surface - mounting type antenna 40 in the antenna device 50 . therefore , hereinafter , the grounding terminal 33 is called the connecting terminal 33 . more , the equivalent circuit of the antenna device 60 is basically the same as in fig3 and the explanation is omitted here . in the antenna device 60 constructed in this way , in proportion to the inductance l 2 by the linear pattern 52 increased , the length of the base member 31 is able to be reduced to shorten the length of the radiation electrode 32 as in the antenna device 50 . accordingly , it is possible to make the surface - mounting type antenna 30 smaller - sized and to reduce the occupied space of the surface - mounting type antenna . further , it is possible to increase the bandwidth of the antenna and the antenna gain . further , because the inductance l 2 of the linear pattern 52 formed on the circuit board 2 is able to be designed independently of the surface - mounting type antenna 30 , after the side of the surface - mounting type antenna 30 has been designed to have the most appropriate capacitance c 2 and conductance g , the inductance l 2 for deciding the resonance frequency is able to be independently designed by changing the length and shape of the linear pattern 52 , and accordingly the freedom for mounting the surface - mounting type antenna is able to be increased . furthermore , it is possible to increase the antenna gain more by the surface - mounting type antenna 30 arranged so as to direct the portion having the connecting terminal 33 formed , of the base member 31 toward a corner portion of the circuit board and to direct the portion having an open - ended terminal 32 a formed , of the radiation electrode 32 in the direction of being separated from a corner portion on the side edge of the circuit board 2 . in fig5 further another preferred embodiment of an antenna device of the present invention is shown . in fig5 to the same or equivalent portions as in fig4 the same reference numerals are given and their explanation is omitted . in the antenna device 70 shown in fig5 the external connecting electrode 51 disposed in an area 2 a having no circuit - board grounding electrode disposed on the circuit board 2 is connected to the circuit - board grounding electrode 3 through an inductance circuit 73 made up of a relatively short connecting wiring 71 having less inductance and a chip - inductor 72 . that is , instead of the linear pattern 52 in the antenna device 60 , the inductance circuit 73 composed of a connecting wiring 71 and a chip - inductor 72 is given . even if the inductance circuit is composed of a connecting wiring 71 and a chip - inductor 72 in this way , the antenna device 70 is quite the same as the antenna device 60 from the viewpoint of equivalent circuit and shows the same working - effect as the surface - mounting type antenna 60 , except that the occupied space by the antenna is slightly increased in accordance with the height of the chip - inductor . in fig6 further another preferred embodiment of an antenna device of the present invention is shown . in fig6 to the same or equivalent portions as in fig4 the same reference numerals are given and their explanation is omitted . in the antenna device 80 shown in fig6 one end of the linear pattern 52 is connected to an external connecting electrode 51 , and the other end of the linear pattern 52 is connected to a switching electrode 88 through the variable inductance circuit 86 composed of a diode 81 , a chip - inductor 82 , a chip - capacitor 83 , a chip - resistro 84 , and a chip - capacitor 85 . here , in the variable inductance circuit 86 , the other end of the linear pattern 52 is connected to the circuit - board grounding electrode 3 through a diode 81 . further , the other end of the linear pattern 52 is connected to the switching electrode 88 through a chip - inductor 82 and a chip - resistor 84 . and both ends of the chip - resistor 84 are connected to the circuit - board grounding electrode 3 through a chip - capacitor 83 and a chip - capacitor 85 respectively . here , in fig7 an equivalent circuit of the antenna device 80 is shown . in fig7 to the same or equivalent portions as in fig3 the same reference numerals are given and their explanation is omitted . in fig7 a diode d represents the diode 81 , inductance l 3 the inductance component of the chip - inductor 82 , capacitance c 3 the capacitance component of the chip - capacitor 83 , resistance r 3 the resistance component of the chip - resistor 84 , and capacitance c 4 the capacitance component of the chip - capacitor 85 respectively . one end of resistance r 2 is grounded through the diode d , and connected to the switching electrode 88 through the inductance l 3 and resistance r 3 . and both ends of resistance r 3 are grounded through capacitance c 3 and capacitance c 4 respectively . here , the resistance r 3 limits the direct current flowing through the diode d . further , the capacitance c 3 functions so as to lower the impedance at the resonance frequency of the antenna device 80 and to ground the connecting portion between the inductance l 3 and resistance r 3 at high frequencies . further , the capacitance c 4 functions as a bypass capacitor . and the resonance frequency of the antenna device 80 is determined mainly by the inductance l 1 , l 2 , and l 3 , and capacitance c 2 . in the antenna device 80 thus constructed , when no voltage or any negative voltage is applied to the switching electrode 88 , the diode d is turned into nonconductive state . because of this , the resonance frequency of the antenna device 80 is determined mainly by the inductance l 1 , l 2 , and l 3 , and the capacitance c 2 . on the other hand , when a positive voltage over a certain level is applied to the switching electrode 88 , the diode d is biased in the forward direction and turned into a conductive state , that is , the state of the connecting portion between the resistance r 2 and inductance l 3 being grounded . because of this , the resonance frequency of the antenna device 80 comes to be determined mainly by the inductance l 1 and l 2 and the capacitance c 2 , and becomes higher than at the time when the diode d is in nonconductive state . because of this fact , it is understood that the resonance frequency of the antenna device 80 is able to be changed by the voltage applied to the switching electrode 88 . therefore , in the antenna device 80 of the present invention , in addition to the working - effect of each of the above - described antenna devices the resonance frequency is able to be easily changed . more , the variable inductance circuit is not limited to this construction . when the value of inductance is able to be changed by allowing a diode to function as a high - frequency switch , any construction is acceptable . further , in each of the above - described preferred embodiments , the radiation electrode of the surface - mounting type antenna was formed in a linear shape or in the shape of letter l , but others in the shape of letter u , in a meandering shape , etc . are acceptable . further , it was stated that the base member of the surface - mounting type antenna is made up of a dielectric substance such as ceramics , resin , etc ., but a magnetic substance is also able to be used . in fig8 one preferred embodiment of a communication device including an antenna device of the present invention is shown . in fig8 the communication device 90 is composed of a circuit board 92 given in an enclosure 91 , and a circuit - board grounding electrode 93 , a power - supply line 94 , and a linear pattern 95 are disposed on the circuit board 92 . in a corner portion of the circuit board 92 , there is an area in which the circuit - board grounding electrode 93 is not formed and in this area a surface - mounting type antenna 30 is mounted . the antenna device is composed of the surface - mounting type antenna 30 the grounding terminal ( not illustrated ) of which is connected to the circuit - board grounding electrode 93 through the linear pattern 95 on the circuit board 92 and of the power - supply terminal ( not illustrated ) which is connected to the power - supply line 94 on the circuit board 92 . furthermore , the power - supply line 94 is connected to a transmission circuit 97 and reception circuit 98 formed on the circuit board 92 through a switching circuit 96 formed on the same circuit board 92 . in this way , by using an antenna device of the present invention , the freedom of mounting each of the parts in the communication device 90 is increased , and the bandwidth and antenna gain of the communication device 90 is able to be increased . more , in the preferred embodiment of fig8 the communication device 90 is composed of an antenna device 60 , but the use of antenna devices 50 , 70 , 80 also gives the same working - effect . according to a surface - mounting type antenna and an antenna device of the present invention , by grounding the other end of the radiation electrode composed of a surface - mounting type antenna having one end as an open - ended terminal through an inductance circuit made up of a linear pattern , a chip - inductor , etc . provided on a circuit board , the surface - mounting type antenna is made small - sized and the occupied space by the antenna is able to be reduced . further , it is possible to widen the bandwidth and improve the antenna gain . further , because the radiation resistance is able to be designed on the side of the surface - mounting type antenna and the resonance frequency on the side of the circuit board independently , the freedom of designing the antenna device is able to be increased . further , by arrangement in the vicinity of the corner portion of the circuit board so as to direct the portion having a connecting terminal formed , of the base member toward a corner portion of the circuit board and to direct the portion having an open - ended terminal , of the radiation electrode in the direction of being separated from the comer portion on the side edge of the circuit board , the antenna gain is able to be further increased . further , by construction of an inductance circuit using a variable inductance circuit having diodes , the resonance frequency of the antenna is able to be changed . further , according to a communication device of the present invention , by using the above - mentioned antenna device , the freedom of mounting each of the parts inside the communication device is increased , and the bandwidth and antenna gain are able to be increased . while the invention has been particularly shown and described with reference to preferred embodiments thereof , it will be understood by those skilled in the art that the forgoing and other changes in form and details may be made therein without departing from the spirit of the invention .