Abstract:
A ground radiation antenna is disclosed. Herein, the ground radiation antenna provides a radiator-forming circuit, which is formed to have a simple structure using a capacitive element, as well as a feeding circuit suitable for the provided radiator-forming circuit. Thus, the structure of the antenna becomes simpler and the size of the antenna becomes smaller. Accordingly, the fabrication process of the antenna is simplified, thereby largely reducing the fabrication cost.

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §120 and §365(c) to a prior PCT International Patent Application No. PCT/KR2010/009338 (filed on Dec. 24, 2010 and designating the U.S.), which claims priority to Korean Patent Application Nos. 10-2010-0012775 (filed on Feb. 11, 2010), 10-2010-0032922 (filed on Apr. 9, 2010), 10-2010-0043186 (filed on May 7, 2010), 10-2010-0043189 (filed on May 7, 2010), 10-2010-0043190 (filed on May 7, 2010), 10-2010-0056207 (filed on Jun. 14, 2010) and 10-2010-0133919 (filed on Dec. 23, 2010), which are all hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an antenna and, more particularly, to a ground radiation antenna using ground radiation of a wireless communication terminal. 
     2. Related Art Technology 
     An antenna is a device that receives RF signals from air into a wireless communication terminal or transmits RF signals from a wireless communication terminal to air. In other words, the antenna is an essential element used in wireless communication. Recently, the mobile telecommunication terminals are required to be compact in size, lightweight, and equipped with a slimmer antenna structure. Also, as the data size being transmitted and received through wireless communication has become larger, mobile telecommunication terminals need antennas providing greater performance. 
     Accordingly, the ground radiation antenna has been proposed to meet such demands. Herein, the ground radiation antenna uses the ground to radiate RF signals. More specifically, a radiator of a related art antenna is provided with a separate radiator occupying a large volume inside or outside of the mobile telecommunication terminal. However, by using the ground as the radiator, the ground being essentially provided in a wireless communication terminal, the size of the antenna may be largely reduced in the ground radiation antenna. 
     However, even in the ground radiation antenna, the radiator cannot be fully functional by using only the ground. Therefore, the ground radiation antenna is additionally provided with a separate radiating element, which performs the role of the radiator along with the ground. 
     Accordingly, the related art ground radiation antenna is disadvantageous in that, due to the radiating element having a large volume and a complex structure, the size of the ground radiation antenna became larger, and the fabrication process of the antenna became very complex. 
     SUMMARY OF THE INVENTION 
     Object of the Invention 
     An object of the present invention is to provide a ground radiation antenna having a remarkably simple structure and also showing an excellent radiating performance. 
     Technical Solutions of the Invention 
     Based upon the characteristics of the ground antenna itself, the present invention provides a radiator-forming circuit using a capacitive element that can replace the radiating element having a complex structure. 
     Additionally, the present invention also provides a feeding scheme that can maximize the radiating performance, while having a simple structure. 
     As described above, by fabricating an antenna using a radiator-forming circuit and a feeding circuit each having a noticeably simplified structure, the present invention provides an antenna that is smaller in size and that shows an excellent radiating performance. 
     Effect of the Invention 
     The ground radiation antenna according to the present invention is advantageous in that the antenna is configured of an extremely simple structure, thereby being capable of reducing the size of the antenna. 
     Also, due to its simple structure, the ground radiation antenna according to the present invention may simplify the fabrication process, thereby being capable of reducing the fabrication cost to a remarkable level. 
     Furthermore, the ground radiation antenna according to the present invention may have the characteristics of a broad-band and a multi-band and may provide users with an excellent radiation performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an antenna using ground radiation according to a first embodiment of the present invention; 
         FIG. 2  illustrates an antenna using ground radiation according to a second embodiment of the present invention; 
         FIG. 3  illustrates an antenna using ground radiation according to a third embodiment of the present invention; 
         FIG. 4  illustrates an antenna using ground radiation according to a fourth embodiment of the present invention; 
         FIG. 5  illustrates an antenna using ground radiation according to a fifth embodiment of the present invention; 
         FIG. 6  illustrates an antenna using ground radiation according to a sixth embodiment of the present invention; 
         FIG. 7  illustrates an antenna using ground radiation according to a seventh embodiment of the present invention; and 
         FIG. 8  illustrates an antenna using ground radiation according to an eighth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the related art antenna, efforts were made to enhance the radiation performance by separately equipping the antenna with a radiating element for ground radiation, and by varying the formation or structure of the radiating element. More specifically, efforts were made for realizing a radiator by combining an element having both inductance and capacitance with a capacitor and an inductor. 
     However, the applicant was able to discover that an excellent ground radiating element could be fabricated when using the inductance of the ground, by simply connecting the capacitor to the ground, without having to use a separate element configured of a complex structure. 
     In order to function as the radiating element of the antenna, the capacitor having the capacitance and the inductor having the inductance should both exist so as to create a resonance. The application also discovered that, since the ground provides the inductance required to generate the resonance, only the capacitor and the ground were required to perform the function of the radiating element without separate elements for providing the inductance. 
     However, the related art ground radiators were incapable of efficiently using the inductance provided from the ground. And, accordingly, efforts were made in the related art in trying to generate resonance by configuring elements having a complex structure and being provided with both capacitance and inductance. 
     Conversely, according to the present invention, by being capable of efficiently using the inductance provided from the ground itself, a radiator having a simple structure may be configured to connect the capacitor to the ground, and an antenna using the above-described radiator may be provided. 
       FIG. 1  illustrates an antenna using ground radiation according to a first embodiment of the present invention. 
     Referring to  FIG. 1 , the antenna using ground radiation according to the first embodiment of the present invention includes a feeding part  120  configured of a feeding source  12  and a feeding transmission line  18 , a ground  10 , a first conductor line  11 , an element  15 , a second conductor line  16 , a capacitive element  13 , and a third conductor line  14 . 
     The ground  10  provides a reference voltage inside a telecommunication device, such as a mobile communication user terminal. Generally, it is preferable that a user terminal ground is formed in a printed circuit board (PCB), wherein circuit devices required for the operation of the user terminal are combined with one another. According to the present invention, in addition to providing the reference voltage, the ground  10  also performs the function of a ground radiator of the antenna. This characteristic is equally applied to the other embodiments of the present invention, which will be described in detail later on. 
     According to the first embodiment of the present invention, the feeding part  120 , the first conductor line  11 , the element  15 , the second conductor line  16 , the capacitive element  13 , and the third conductor line  14  collectively operate as a feeding circuit for exciting the antenna, so that radiation of an RF signal can occur through the antenna radiator. Additionally, the first conductor line  11 , the element  15 , the second conductor line  16 , the capacitive element  13 , and the third conductor line  14  operate as an antenna radiator-forming circuit, which enables the RF signal to be actually radiated. More specifically, according to the first embodiment of the present invention, the first conductor line  11 , the element  15 , the second conductor line  16 , the capacitive element  13 , and the third conductor line  14  not only correspond to portions of the feeding circuit of the antenna but also correspond to portions of a radiator-forming circuit. 
     According to the first embodiment of the present invention, the element  15  may correspond to an inductive element, a capacitive element, or a simple conductive line. 
     According to the first embodiment of the present invention, the feeding part  120  is configured of a coplanar waveguide (CPW). However, in addition to the CPW, a variety of other types of feeding part may be configured in the present invention. Such characteristic is equally applied to the other embodiments of the present invention. 
     According to the first embodiment of the present invention, the feeding circuit is configured inside of a clearance area  100 . The clearance area  100  corresponds to an area within the user terminal ground  10  having a portion of the ground removed therefrom. 
     According to the first embodiment of the present invention, it is preferable that the capacitive element corresponds to a lumped circuit element, such as a chip capacitor. However, in addition to the chip capacitor, a capacitive element having a general capacitive structure may also be used in the first embodiment of the present invention. Furthermore, the capacitive element may either be configured of a single capacitor, or may be configured by connecting two or more capacitors to one another. 
     Meanwhile, according to the first embodiment of the present invention, in order to obtain a specific capacitance, the capacitive element  13  may use a combination of multiple elements. For example, the capacitive element  13  may be replaced with a combined structure of a capacitive element and an inductive element. 
     Furthermore, in the other embodiments of the present invention that will be described hereinafter, in order to obtain a specific capacitance, the capacitive element may use a combination of multiple elements. For example, the capacitive element may be replaced with a combined structure of a capacitive element and an inductive element. 
       FIG. 2  illustrates an antenna using ground radiation according to a second embodiment of the present invention. 
     Referring to  FIG. 2 , the antenna using ground radiation according to the second embodiment of the present invention includes a feeding part  220  configured of a feeding source  22  and a feeding transmission line  28 , a ground  20 , a first conductor line  21   a , a first element  25 , a second conductor line  21   b , a capacitive element  23 , a third conductor line  24   a , a fourth conductor line  24   b , a second element  27 , and a fifth conductor line  24   c.    
     Herein, the feeding part  220 , the first conductor line  21   a , the first element  25 , the second conductor line  21   b , the fourth conductor line  24   b , the capacitive element  23 , and the third conductor line  24   a  collectively operate as a feeding circuit for exciting the antenna, so that radiation of an RF signal can occur through the antenna radiator. Furthermore, the first conductor line  21   a , the first element  25 , the second conductor line  21   b , the fourth conductor line  24   b , the capacitive element  23 , and the third conductor line  24   a  operate in collaboration (or collectively) as an antenna radiator-forming circuit, which enables the RF signal to be actually radiated. More specifically, according to the second embodiment of the present invention, the first conductor line  21   a , the first element  25 , the second conductor line  21   b , the fourth conductor line  24   b , the capacitive element  23 , and the third conductor line  24   a  not only correspond to portions of the feeding circuit of the antenna but also correspond to portions of a radiator-forming circuit. 
     Meanwhile, the fifth conductor line  24   c  and the second element  27  correspond to elements that are added in order to facilitate impedance matching of the first embodiment of the present invention. 
     According to the second embodiment of the present invention, the first element  25  may correspond to an inductive element, a capacitive element, or a simple conductive line. And, the second element  27  may correspond to an inductive element or a simple conductive line. 
     According to the second embodiment of the present invention, the feeding circuit is configured inside of a clearance area  200 . The clearance area  200  corresponds to an area within the user terminal ground  20  having a portion of the ground removed therefrom. 
     According to the second embodiment of the present invention, it is preferable that the capacitive element corresponds to a lumped circuit element, such as a chip capacitor. However, in addition to the chip capacitor, a capacitive element having a general capacitive structure may also be used in the second embodiment of the present invention. Furthermore, the capacitive element may either be configured of a single capacitor, or may be configured by connecting two or more capacitors to one another. 
       FIG. 3  illustrates an antenna using ground radiation according to a third embodiment of the present invention. 
     Referring to  FIG. 3 , the antenna using ground radiation according to the third embodiment of the present invention includes a feeding part  320  configured of a feeding source  32  and a feeding transmission line  38 , a ground  30 , a first conductor line  31   a , a first element  35 , a second conductor line  31   b , a first capacitive element  33 , a third conductor line  34   a , a fourth conductor line  34   b , a second element  37 , a fifth conductor line  34   c , a sixth conductor line  36   a , a second capacitive element  39 , and a seventh conductor line  36   b.    
     Herein, the feeding part  320 , the first conductor line  31   a , the first element  35 , the second conductor line  31   b , the fourth conductor line  34   b , the first capacitive element  33 , and the third conductor line  34   a  collectively operate as a first feeding circuit for exciting the antenna, so that radiation of an RF signal can occur through the antenna radiator. 
     Also, the first conductor line  31   a , the first element  35 , the second conductor line  31   b , the fourth conductor line  34   b , the first capacitive element  33 , and the third conductor line  34   a  operate in collaboration (or collectively) as a first antenna radiator-forming circuit, which enables the RF signal to be actually radiated. 
     More specifically, according to the third embodiment of the present invention, the first conductor line  31   a , the first element  35 , the second conductor line  31   b , the fourth conductor line  34   b , the first capacitive element  33 , and the third conductor line  34   a  not only correspond to portions of the feeding circuit of the antenna but also correspond to portions of a radiator-forming circuit. 
     Additionally, the feeding part  320 , the first conductor line  31   a , the first element  35 , the second conductor line  31   b , the sixth conductor line  36   a , the second capacitive element  39 , and the seventh conductor line  36   b  collectively operate as a second feeding circuit for exciting the antenna, so that radiation of an RF signal can occur through the antenna radiator. 
     Also, the first conductor line  31   a , the first element  35 , the second conductor line  31   b , the sixth conductor line  36   a , the second capacitive element  39 , and the seventh conductor line  36   b  operate in collaboration (or collectively) as a second antenna radiator-forming circuit, which enables the RF signal to be actually radiated. 
     More specifically, according to the third embodiment of the present invention, the first conductor line  31   a , the first element  35 , the second conductor line  31   b , the sixth conductor line  36   a , the second capacitive element  39 , and the seventh conductor line  36   b  not only correspond to portions of the feeding circuit of the antenna but also correspond to portions of a radiator-forming circuit. 
     The antenna according to the third embodiment of the present invention may realize a multi-band characteristic due to a double antenna radiator-forming circuit. 
     Meanwhile, the fifth conductor line  34   c  and the second element  37  correspond to elements that are added in order to facilitate impedance matching. 
     According to the third embodiment of the present invention, the first element  35  may correspond to an inductive element, a capacitive element, or a simple conductive line. And, the second element  37  may correspond to an inductive element or a simple conductive line. 
     According to the third embodiment of the present invention, the feeding circuit is configured inside of a clearance area  300 . The clearance area  300  corresponds to an area within the user terminal ground  30  having a portion of the ground removed therefrom. 
     According to the third embodiment of the present invention, it is preferable that the capacitive element corresponds to a lumped circuit element, such as a chip capacitor. However, in addition to the chip capacitor, a capacitive element having a general capacitive structure may also be used in the third embodiment of the present invention. Furthermore, the capacitive element  13  may either be configured of a single capacitor, or may be configured by connecting two or more capacitors to one another. 
       FIG. 4  illustrates an antenna using ground radiation according to a fourth embodiment of the present invention. 
     Although the antenna according to the fourth embodiment of the present invention has the same structure as the antenna according to the second embodiment of the present invention, a separate clearance is not formed in the antenna according to the fourth embodiment of the present invention. Furthermore, the antenna according to the fourth embodiment of the present invention is configured in an area that is not surrounded by the ground. 
       FIG. 5  illustrates an antenna using ground radiation according to a fifth embodiment of the present invention. 
     Although the antenna according to the fifth embodiment of the present invention has the same structure as the antenna according to the third embodiment of the present invention, a separate clearance is not formed in the antenna according to the fifth embodiment of the present invention. Furthermore, the antenna according to the fifth embodiment of the present invention is configured in an area that is not surrounded by the ground. 
       FIG. 6  illustrates an antenna using ground radiation according to a sixth embodiment of the present invention. 
     Just as the antenna according to the fifth embodiment of the present invention, although the antenna according to the sixth embodiment of the present invention has the same basic structure as the antenna according to the third embodiment of the present invention, a separate clearance is not formed in the antenna according to the sixth embodiment of the present invention. Furthermore, the antenna according to the sixth embodiment of the present invention is configured in an area that is not surrounded by the ground. 
     However, unlike in the fifth embodiment of the present invention, in the antenna according to the sixth embodiment of the present invention, the capacitance element  63  is directly connected to the ground  60 , and the capacitance element  63  does not meet with the conductor line  62 , which connects the element  61  and the ground  60 . 
       FIG. 7  illustrates an antenna using ground radiation according to a seventh embodiment of the present invention. 
     Although the antenna according to the seventh embodiment of the present invention has the same basic structure as the antenna according to the second embodiment of the present invention, the shape of the clearance is different from the antenna according to the second embodiment of the present invention. 
     More specifically, the clearance of the antenna according to the second embodiment of the present invention has three sides surrounded by the ground, and only one side of the clearance is open. However, the clearance  700  of the antenna according to the seventh embodiment of the present invention is formed to have all four sides surrounded by the ground  70 . 
       FIG. 8  illustrates an antenna using ground radiation according to an eighth embodiment of the present invention. 
     Although the antenna according to the eighth embodiment of the present invention has the same basic structure as the antenna according to the third embodiment of the present invention, the shape of the clearance is different from the antenna according to the third embodiment of the present invention. 
     More specifically, the clearance of the antenna according to the third embodiment of the present invention has three sides surrounded by the ground, and only one side of the clearance is open. However, the clearance  800  of the antenna according to the eighth embodiment of the present invention is formed to have all four sides surrounded by the ground  80 . 
     As described above, each of the second, fourth, and seventh embodiments of the present invention belongs to an antenna group having the same basic connection. However, depending upon the shape of the clearance, depending upon whether or not a portion of the antenna or the entire antenna is formed in the clearance, and depending upon whether or not the antenna is formed outside of the clearance, each of the second, fourth, and seventh embodiments may be formed to have a different shape. Therefore, for each identical antenna group, by creating a clearance having two sides surrounded by the ground and two sides open to the outside, and by applying this structure to each embodiment of the present invention, the antenna may be formed to have a wide range of shapes other than the shapes shown in the drawings. 
     Therefore, the clearance having two sides open to the outside may also be applied to the third, fifth, sixth, and eighth embodiments of the present invention, each belonging to the same antenna group.