Abstract:
The present disclosure relates to a pre-5 th -Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4 th -Generation (4G) communication system such as Long Term Evolution (LTE). The present invention relates to an antenna structure for signal radiation in a transmission device. An apparatus for signal radiation includes a feeding unit configured to radiate a signal, and a guiding unit, that consists of a plurality of elements physically spaced from one another, configured to adjust a radiation pattern of the signal radiated by the feeding unit by generating a radio wave in a Transverse Electric (TE) mode. Further, the present invention also includes embodiments different from the above-described embodiment.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an antenna of a wireless transmission device. 
       BACKGROUND ART 
       [0002]    To meet the demand for wireless data traffic having increased since deployment of 4 th  generation (4G) communication systems, efforts have been made to develop an improved 5 th  generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post Long Term Evolution (LTE) System’. 
         [0003]    The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. 
         [0004]    In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like. 
         [0005]    In the 5G system, Hybrid frequency shift keying (FSK) and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed. 
         [0006]    In addition, thanks to the development of technology, communication devices are miniaturized and various electronic devices are providing services based on a network using the communication devices. Accordingly, related-art devices which do not have communication functions mounted therein as well as mobile terminals (for example, cellular phones, smart phones, or the like) which are manufactured for the purpose of communication are providing various services using communication. In this case, it is common that wireless communication technology is applied in order to provide convenience of portability and avoid inconvenience caused by wire communication. 
         [0007]    For wireless communication, an antenna for radiating a signal should be included. In order to transmit a signal through an antenna, a transmission device generates a baseband signal from transmission data and generates a Radio Frequency (RF) through a Radio Frequency Integrated Circuit (RFIC). 
         [0008]    The RFIC and the antenna are normally connected with each other through a transmission line. However, the transmission of the signal through the transmission line may cause loss of a transmission signal. The loss of the transmission signal may reduce an antenna gain and eventually may cause deterioration of performance of the system. 
       DETAILED DESCRIPTION OF THE INVENTION 
     Technical Objects 
       [0009]    An exemplary embodiment of the present invention provides an apparatus for enhancing an antenna gain in a wireless transmission device. 
         [0010]    Another exemplary embodiment of the present invention provides an apparatus for reducing loss which is caused by a transmission line in a wireless transmission device. 
         [0011]    Another exemplary embodiment of the present invention provides an antenna apparatus which has a minimized transmission line in a wireless transmission device. 
       Technical Solving Means 
       [0012]    According to an exemplary embodiment of the present invention, an apparatus for signal radiation includes: a feeding unit which radiates a signal; and a guiding unit that consists of a plurality of elements physically spaced from one another, and adjusts a radiation pattern of the signal radiated by the feeding unit. 
         [0013]    According to an exemplary embodiment of the present invention, a method for operating of a transmission device includes: radiating a signal; and adjusting a radiation pattern of the signal through a guiding unit which is formed of a plurality of elements physically spaced from one another. 
       Advantageous Effect 
       [0014]    Through a structure in which a transmission line between a Radio Frequency Integrated Circuit (RFIC) and an antenna is removed in a wireless transmission device, an antenna gain can be enhanced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  illustrates an example of a connection structure of a Radio Frequency Integrated Circuit (RFIC) and an antenna in a transmission device; 
           [0016]      FIG. 2  illustrates a connection structure of an RFIC and an antenna in a transmission device according to an exemplary embodiment of the present invention; 
           [0017]      FIG. 3  illustrates a configuration example of an antenna in a transmission device according to an exemplary embodiment of the present invention; 
           [0018]      FIG. 4  illustrates a criterion for measuring of an antenna in a transmission device according to an exemplary embodiment of the present invention; 
           [0019]      FIG. 5  illustrates a radio wave advancing direction and an electric field which are caused by an antenna in a transmission device according to an exemplary embodiment of the present invention; 
           [0020]      FIG. 6  illustrates a structure of an antenna for controlling a polarization characteristic in a transmission device according to an exemplary embodiment of the present invention; 
           [0021]      FIG. 7  illustrates an S-parameter of the antenna in the transmission device according to an exemplary embodiment of the present invention; 
           [0022]      FIG. 8  illustrates design variables for controlling a radiation characteristic of an antenna in a transmission device according to an exemplary embodiment of the present invention; 
           [0023]      FIG. 9  illustrates radiation characteristics according to a length of the antenna in the transmission device according to an exemplary embodiment of the present invention; 
           [0024]      FIG. 10  illustrates radiation characteristics according to a distance between the guide elements of the antenna in the transmission device according to an exemplary embodiment of the present invention; 
           [0025]      FIG. 11  illustrates a radiation characteristic according to a size of the guide element of the antenna in the transmission device according to an exemplary embodiment of the present invention; 
           [0026]      FIGS. 12A and 12B  illustrate an example of a structure for controlling a feeding direction of an antenna in a transmission device according to an exemplary embodiment of the present invention; 
           [0027]      FIG. 13  illustrates an example of a radiation characteristic according to a feeding direction of an antenna in a transmission device according to an exemplary embodiment of the present invention; 
           [0028]      FIG. 14  illustrates another example of a radiation characteristic according to a feeding direction of an antenna in a transmission device according to an exemplary embodiment of the present invention; 
           [0029]      FIG. 15  illustrates an example of a radiation characteristic when two antennas are used in the transmission device according to an exemplary embodiment of the present invention; 
           [0030]      FIG. 16  illustrates an example of a radiation characteristic when four antennas are used in the transmission device according to an exemplary embodiment of the present invention; 
           [0031]      FIG. 17  illustrates examples of beam steering which uses a plurality of antennas in the transmission device according to an exemplary embodiment of the present invention; 
           [0032]      FIG. 18  illustrates a configuration example of an antenna in a transmission device according to another exemplary embodiment of the present invention; 
           [0033]      FIG. 19  illustrates a configuration example of an antenna in a transmission device according to another exemplary embodiment of the present invention; 
           [0034]      FIG. 20  illustrates a signal transmission procedure in the transmission device according to an exemplary embodiment of the present invention; 
           [0035]      FIG. 21  illustrates an example of utilization of the antenna according to an exemplary embodiment of the present invention; 
           [0036]      FIG. 22  illustrates radiation patterns of a wireless probe to which the antenna is applied according to an exemplary embodiment of the present invention; 
           [0037]      FIG. 23  illustrates arrangement of antennas installed in a wireless probe according to an exemplary embodiment of the present invention; and 
           [0038]      FIG. 24  illustrates arrangement of antennas installed in a wireless probe with a heat sink plate according to an exemplary embodiment of the present invention. 
       
    
    
     BEST MODE FOR EMBODYING THE INVENTION 
       [0039]    Operation principles of the present invention will be described in detail herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Also, the terms used herein are defined according to the functions of the present invention. Thus, the terms may vary depending on user&#39;s or operator&#39;s intension and usage. That is, the terms used herein must be understood based on the descriptions made herein. 
         [0040]    Hereinafter, the present invention will be described regarding technology for signal radiation in a wireless transmission device. A term indicating a component of an antenna, which is used in the following description, a term for explaining a radio wave characteristic, or the like are just for the convenience of explanation. Therefore, the present invention is not limited to the terms described below and other terms indicating an object having the same technical meaning may be used. 
         [0041]    In the present invention, the wireless transmission device may be a portable electronic device, and may be a communicating means which is included in one of a smart phone, a portable terminal, a mobile phone, a mobile pad, a media player, a tablet computer, a handheld computer, or a Personal Digital Assistant (PDA). In addition, the wireless transmission device may be a communicating means for a device which combines the functions of two or more of the above-mentioned devices. 
         [0042]    A structure of a device including a normal antenna is as illustrated in  FIG. 1 .  FIG. 1  illustrates an example of a connection structure of a Radio Frequency Integrated Circuit (RFIC) and an antenna in a transmission device. An example of the connection structure of the RFIC and the antenna is as illustrated in  FIG. 1 . Referring to  FIG. 1 , an RFIC  104  is installed on a board  102  and an antenna  108  is arranged in the proximity of a corner of the board  102 . Furthermore, the RFIC  104  and the antenna  108  are connected with each other through a transmission line  106  in order to transmit an RF signals from the RFIC  104  to the antenna  108 . 
         [0043]    However, the loss of a transmission signal may be caused by the transmission of the signal through the transmission line. The loss of the transmission signal may reduce an antenna gain and eventually may cause deterioration of performance of a system. Accordingly, the present invention suggests a connection structure of an RFIC and an antenna of a structure as shown in  FIG. 2 .  FIG. 2  illustrates a connection structure of an RFIC and an antenna in a transmission device according to an exemplary embodiment of the present invention. 
         [0044]    Referring to  FIG. 2 , the RFIC  204  and the antenna  208  of the transmission device are connected with each other without a transmission line. That is, in order to reduce loss caused by the transmission of a signal through the transmission line, the transmission device according to exemplary embodiments of the present invention includes the connection structure of the RFIC  204  and the antenna  208  in which the transmission line is removed or minimized. The RFIC  204  is a means for performing processing, such as amplifying, filtering, or the like, with respect to an RF signal, and may be referred as a different name. For example, the RFIC  204  may be referred to as a transceiver, an RF processor, or the like. 
         [0045]    According to an exemplary embodiment of the present invention, the antenna  208  may have a shape formed by simply removing a transmission line from a related-art antenna. According to another exemplary embodiment of the present invention, the antenna  208  may further include components for controlling performance of signal radiation in a space where the transmission line is to be disposed, in addition to the shape formed by simply removing the transmission line from the related-art antenna. 
         [0046]      FIG. 3  illustrates a configuration example of an antenna in a transmission device according to an exemplary embodiment of the present invention. 
         [0047]    Referring to  FIG. 3 , the antenna includes a feeding unit  310  and a guiding unit  320 . 
         [0048]    The feeding unit  310  receives an RF signal from an RFIC and radiates the RF signal. The feeding unit  310  performs impedance matching with the antenna. The RF signal from the RFIC may be inputted to the feeding unit  310  through physical connection. That is, the feeding unit  310  may be connected with the RFIC without an extra transmission line. Alternatively, the feeding unit  310  may be connected with the RFIC through a transmission line having a length which is shorter than a threshold. In the case of  FIG. 3 , the feeding unit  310  is illustrated as including a plurality of sub units. However, the structure of the feeding unit  310  illustrated in  FIG. 3  is merely an example and the feeding unit  310  may have a different structure. 
         [0049]    The guiding unit  320  radiates the signal radiated from the feeding unit  310  to the outside in a desired radiation pattern. That is, the signal radiated from the feeding unit  310  is radiated to the outside of the transmission device through the guiding unit  320 . In this case, the radiation pattern may vary according to a detailed structure of the guiding unit  320 . The guiding unit  320  is formed of a plurality of guide elements and the guide elements are arranged in a predetermined direction. The guide elements are physically spaced from one another, and a distance between neighbor guide elements may be regular or irregular, or may be substantially regular within a pre-defined error range. 
         [0050]      FIG. 4  illustrates a criterion for measuring of an antenna in a transmission device according to an exemplary embodiment of the present invention. In  FIG. 4 , view (a) illustrates a plane view of the antenna and view (b) illustrates a front view of the antenna. 
         [0051]    Referring to  FIG. 4 , a feeding unit  410  and a guiding unit  420  are disposed in a dielectric  440 . The feeding unit  410  and the guiding unit  420  may be disposed in the form of connection to the inside of the dielectric  440 , or the dielectric  440  may be installed in the form of a cover which is placed above the feeding unit  410  and the guiding unit  420 . In this case, as shown in view (b), some of the guide elements of the guiding unit  420  may be exposed to the outside of the dielectric  440 . The dielectric  440  may be configured by at least one of a Printed Circuit Board (PCB), silicon, Low Temperature Co-fired Ceramics (LTCC), Liquid Crystal Polymer (LCP). 
         [0052]    As shown in view (a), the dielectric  440  is enclosed by a conductor  430  on the plane view. In addition, as shown in view (b), one surface of the dielectric  440  may not be enclosed by the conductor  430  and may be opened. That is, some of the surfaces parallel to the longitudinal direction of the guiding unit  420  are shielded by the conductor  430  and the other surfaces are opened. For example, the opened surface may include a surface through which the guide elements of the guiding unit  420  are exposed to the outside of the dielectric  440 . 
         [0053]    In the above-described structure, a size of the dielectric  440  on the x-axis is designated as a length, and a size on the y-axis is designated as a width as shown in view (a). In addition, as shown in view (b), a size of the dielectric on the z-axis is designated as a height. The definition of the length, the width, and the height is merely an example for the convenience of explanation. Accordingly, the definition of the length, the width, and the height may be modified or changed according to an intention of a practicer of the present invention. 
         [0054]      FIG. 5  illustrates a radio wave advancing direction and an electric field which are caused by the antenna in the transmission device according to an exemplary embodiment of the present invention. In  FIG. 5 , view (a) illustrates an electric field which is observed on the x-y plane corresponding to the front view of the antenna, and view (b) illustrates an electric field which is observed on the x-z plane corresponding to the side view of the antenna. 
         [0055]    Referring to  FIG. 5 , the antenna according to an exemplary embodiment of the present invention generates a radio wave of a Transverse Electric (TE) mode. The TE mode refers to a polarization form which is classified into linear polarization with a Transverse Magnetic (TM) mode, Transverse Electric Magnetic (TEM). The TE mode means linear polarization in which the electric field is perpendicular to the advancing direction of the radio wave. That is, in the antenna according to an exemplary embodiment of the present invention, the electric field is generated perpendicular to the radio wave advancing direction. In this case, an equation regarding the radio wave is as shown in Equation 1 presented below: 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         ( 
                         
                           
                             
                               ∂ 
                               2 
                             
                             
                               ∂ 
                               
                                 x 
                                 2 
                               
                             
                           
                           + 
                           
                             
                               ∂ 
                               2 
                             
                             
                               ∂ 
                               
                                 y 
                                 2 
                               
                             
                           
                           + 
                           
                             ∂ 
                             
                               ∂ 
                               
                                 z 
                                 2 
                               
                             
                           
                           + 
                           
                             k 
                             2 
                           
                         
                         ) 
                       
                        
                       Hz 
                     
                     = 
                     0 
                   
                   , 
                   
                     Hz 
                     = 
                     
                       
                         
                           h 
                           z 
                         
                          
                         
                           ( 
                           
                             x 
                             , 
                             y 
                           
                           ) 
                         
                       
                        
                       
                          
                         
                           
                             - 
                             j 
                           
                            
                           
                               
                           
                            
                           β 
                            
                           
                               
                           
                            
                           z 
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   1 
                 
               
             
           
         
       
     
         [0056]    In equation 1, k is a propagation constant, Hz is an z-axis value of a magnetic field, h z  is an amplitude of the z-axis value of the magnetic field, βz is a phase constant which advances on the z-axis. 
         [0057]      FIG. 6  illustrates a structure of an antenna for controlling a polarization characteristic in a transmission device according to an exemplary embodiment of the present invention.  FIG. 6  illustrates a simplified structure of the antenna corresponding to the front view of the antenna. In  FIG. 6 , the x-axis and the y-axis are different from the x-axis and the y-axis defined in  FIG. 3 , and the x-axis of  FIG. 6  is consistent with the y-axis of  FIG. 3  and the y-axis of  FIG. 6  is consistent with the z-axis of  FIG. 3 . 
         [0058]    Referring to  FIG. 6 , three surfaces except for a first surface  670  out of the four surfaces of the antenna are in a short state, and the first surface is opened. That is, the three of the four surfaces of the antenna are shielded by the conductor, and the other surface, the first surface  670 , is opened. In this case, a boundary condition is as shown in Equation 2 presented below: 
         [0000]    
       
         
           
             
               
                 
                   { 
                   
                     
                       
                         
                           
                             
                               
                                 ife 
                                 x 
                               
                               = 
                               0 
                             
                             , 
                           
                         
                         
                           
                             y 
                             = 
                             0 
                           
                         
                       
                       
                         
                           
                             
                               
                                 ife 
                                 x 
                               
                               = 
                               T 
                             
                             , 
                           
                         
                         
                           
                             y 
                             = 
                             0 
                           
                         
                       
                     
                      
                     
                       
 
                     
                      
                     
                       { 
                       
                         
                           
                             
                               
                                 
                                   ife 
                                   y 
                                 
                                 = 
                                 0 
                               
                               , 
                             
                           
                           
                             
                               x 
                               = 
                               0 
                             
                           
                         
                         
                           
                             
                               
                                 
                                   ife 
                                   y 
                                 
                                 = 
                                 0 
                               
                               , 
                             
                           
                           
                             
                               x 
                               = 
                               α 
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   2 
                 
               
             
           
         
       
     
         [0059]    In equation 2, e x  is an x-axis component of the electric field, y is a size of the antenna in a height direction, e y  is an y-axis component of the electric field, and x is a size of the antenna in a width direction. 
         [0060]    In addition, an example of a condition of the size of the antenna in the height direction and the size in the width direction according to a frequency of a transmission signal is as shown in Equation 3 presented below, for example: 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       k 
                       c 
                       2 
                     
                     = 
                     
                       
                         
                           k 
                           x 
                           2 
                         
                         + 
                         
                           k 
                           y 
                           2 
                         
                       
                       = 
                       
                         
                           - 
                           
                             β 
                             2 
                           
                         
                         + 
                         
                           k 
                           2 
                         
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       f 
                       c 
                     
                     = 
                     
                       
                         1 
                         
                           2 
                            
                           Π 
                            
                           
                             
                               μ 
                                
                               
                                   
                               
                                
                               ɛ 
                             
                           
                         
                       
                        
                       
                         
                           
                             
                               ( 
                               
                                 
                                   m 
                                    
                                   
                                       
                                   
                                    
                                   Π 
                                 
                                 a 
                               
                               ) 
                             
                             2 
                           
                           + 
                           
                             
                               ( 
                               
                                 
                                   
                                     ( 
                                     
                                       
                                         2 
                                          
                                         n 
                                       
                                       + 
                                       1 
                                     
                                     ) 
                                   
                                   ∏ 
                                 
                                 
                                   2 
                                    
                                   b 
                                 
                               
                               ) 
                             
                             2 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   3 
                 
               
             
           
         
       
     
         [0061]    In equation 3, k c  is a propagation constant of a cutoff frequency band, k x  is an x-axis component of the propagation constant, k y  is a y-axis component of the propagation constant, β is a phase constant of a radio wave advancing direction, k is a propagation constant, f c  is a frequency of a transmission signal, H is pi, μ is permeability of an inner medium of the antenna, ∈ is permittivity of the inner medium of the antenna, a is a size of the antenna in the width direction, n is a certain natural number, and b is a size of the antenna in the height direction. 
         [0062]    The TE mode may be divided into a TE 10  mode and a TE 01  mode. The TE 10  mode and the TE 01  mode are divided according to a length of a cutoff wave length, and the TE 10  mode is a mode in which the cutoff wave length is two times longer than the size of the antenna in the width direction, and TE 01  mode is a mode in which the cutoff wave length is two times longer than the size of the antenna in the height irection. When Equation 3 is rearranged, the frequency in the TE 10  mode and the TE 01  mode may be expressed by Equation 4 presented below: 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       f 
                       
                         TE 
                          
                         
                             
                         
                          
                         10 
                       
                     
                     = 
                     
                       
                         1 
                         
                           2 
                            
                           
                             π 
                              
                             
                               ( 
                               
                                 μɛ 
                                  
                                 
                                   · 
                                   5 
                                 
                               
                               ) 
                             
                           
                         
                       
                        
                       
                         
                           ( 
                           
                             π 
                             width 
                           
                           ) 
                         
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       f 
                       
                         TE 
                          
                         
                             
                         
                          
                         01 
                       
                     
                     = 
                     
                       
                         1 
                         
                           ( 
                           
                             μɛ 
                              
                             
                               · 
                               5 
                             
                           
                           ) 
                         
                       
                        
                       
                         
                           ( 
                           
                             
                               3 
                                
                               π 
                             
                             
                               2 
                                
                               
                                   
                               
                                
                               height 
                             
                           
                           ) 
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   4 
                 
               
             
           
         
       
     
         [0063]    In equation 4, f TE10  is a transmission signal frequency in the TE 10  mode, μ is permeability of the inner medium of the antenna, ∈ is permittivity of the inner medium of the antenna, width is a size of the antenna in the width direction, f TE01  is a transmission signal frequency in the TE 01  mode, and height s a size of the antenna in the height direction. 
         [0064]    In the embodiment shown in  FIG. 3 , the cross section of the antenna is expressed as a rectangle. The antenna having the rectangular cross section is an example and, according to various exemplary embodiments of the present invention, the cross section of the antenna may have other shapes. For example, due to a limitation to an installation space in the transmission device, at least one corner may have an angle other than a right angle or the cross section may have a pentagonal shape or hexagonal shape other than the rectangular shape. 
         [0065]    In the TE 10  mode and the TE 01  mode, an example of an S-parameter which indicates output power relative to input power of the antenna is as shown in  FIG. 7 .  FIG. 7  illustrates an S-parameter of the antenna in the transmission device according to an exemplary embodiment of the present invention. In  FIG. 7 , view (a) illustrates an S-parameter according to a frequency in the TE 10  mode, and view (b) illustrates an S-parameter according to a frequency in the TE 01  mode. In addition, S 11  is a reflection coefficient of an input terminal, and S 12  is a reverse transfer coefficient. Referring to  FIG. 7 , an operation frequency in the TE 10  mode is about 28 GHz and an operation frequency in the TE 01  mode is about 73 GHz. 
         [0066]    As described above, the antenna according to an exemplary embodiment of the present invention includes the feeding unit and the guiding unit, and has a length, a width, and a height. In addition, the guiding unit includes the plurality of guide elements, and the feeding unit and the guiding unit may be disposed in the dielectric. In addition, at least one surface of the dielectric may be shielded by the conductor and the other surface may be opened. 
         [0067]    By adjusting the length, the width, the height, the length of the guiding unit, the distance between the guide elements, the size of each of the guide elements, or the like, different signal radiation patterns may be obtained. Design variables for controlling the signal radiation pattern are as shown in  FIG. 8 .  FIG. 8  illustrates designs variables for controlling a radiation characteristic of an antenna in a transmission device according to an exemplary embodiment of the present invention. 
         [0068]    Referring to  FIG. 8 , individual guide elements  822  forming a guiding unit are arranged at a predetermined distance from one another, and the distance may be referred to as a pitch  824 . The guide element  822  may be designed to have a width  826  on the y-axis and a height  828  on the z-axis. The antenna has a length  852  on the x-axis, a width  854  on the y-axis, and a height  856  on the z-axis. In addition, in the following description, a radiation angle θ  862  of a signal is defined on the x-z plane, a direction coinciding with the x-axis is defined as 90° and a direction coinciding with the z-axis is defined as 0°. 
         [0069]    The radiation angle θ  862  may vary according to the length  852 .  FIG. 9  illustrates radiation characteristics according to the length of the antenna in the transmission device according to an exemplary embodiment of the present invention. In  FIG. 9 , the horizontal axis indicates the length  852  and the unit is a ratio of the length to a wave length. In  FIG. 9 , the vertical axis on the left indicates the radiation angle θ  862  and the vertical axis on the right indicates a gain. Referring to  FIG. 9 , as the length  852  increases, the radiation angle θ  862  increases. That is, as the length  852  decreases, the radiation angle θ  862  is closer to vertical radiation, and, as the length  852  increases, the radiation angle θ  862  is closer to horizontal radiation. 
         [0070]    In addition, the radiation angle θ  862  may vary according to the pitch  824 .  FIG. 10  illustrates radiation characteristics according to the distance between the guide elements of the antenna in the transmission device according to an exemplary embodiment of the present invention. In  FIG. 10 , the horizontal axis indicates the pitch  824  and the unit is a ratio of the pitch to a wave length. In  FIG. 10 , the vertical axis on the left indicates the radiation angle θ  862  and the vertical axis on the right indicates the gain. Referring to  FIG. 10 , as the pitch  824  increases, the radiation angle θ  862  decreases. Compared to the radiation angle, the gain is not greatly changed. 
         [0071]    The gain of the antenna may vary according to the size of the guide element  822 .  FIG. 11  illustrates a radiation characteristic according to the size of the guide element  822  of the antenna in the transmission device according to an exemplary embodiment of the present invention. In  FIG. 11 , the horizontal axis indicates a ratio of size of the width  826  or the height  828  of the guide element  822  to the total size of the antenna, and the vertical axis indicates a gain. Referring to the graph of the width  826 , as the width  826  is closer to 1, the gain increases. However, when the width  826  exceeds 6/7, the gain is reduced. Referring to the graph of the height  828 , the gain increases as the height  828  increases. 
         [0072]    As described above, the radiation characteristics (for example, the radiation angle, the gain, or the like) may vary according to the length of the antenna, the size of the guide element, the pitch of the guide element, or the like. Accordingly, by adjusting the length of the antenna, the size of the guide element, the pitch of the guide element, or the like, various radiation characteristics may be intended. Furthermore, in the antenna according to an exemplary embodiment of the present invention, the radiation characteristics of the signal may vary according to a direction of a current flowing in the feeding unit. The direction of the current flowing in the feeding unit may vary according to a point of the feeding unit at which the signal is inputted and a direction in which the signal is inputted. 
         [0073]      FIGS. 12A and 12B  illustrate examples of a structure for controlling a feeding direction of an antenna in a transmission device according to an exemplary embodiment of the present invention. In  FIGS. 12A and 12B , view (a) illustrates a conceptual switching structure for providing a signal to a feeding unit  1210 , view (b) illustrates signal input points according to a switch connection state, view (c) illustrates other signal input points, and views (d) and (e) illustrate examples of other structures of the feeding unit  1210 . 
         [0074]    Referring to view (a) of  FIG. 12A , an RF signal may be provided to the feeding unit  1210  through an input terminal A  1281  or an input terminal B  1282  through a switch. The switch for selecting the input terminal A  1281  or the input terminal B  1282  may be implemented by using an electronic switch. 
         [0075]    Referring to view (b) of  FIG. 12A , the feeding unit  1210  includes a first sub unit  1212  and a second sub unit  1214 . In the example of view (b) of  FIG. 12A , the first sub unit  121  is disposed to be higher than the second sub unit  1214  on the z-axis. When the RF signal is inputted to the input terminal A  1281  disposed on the side surface of the first sub unit  1212 , the RF signal is inputted through the upper end of the feeding unit  1210 . In this case, the signal may be radiated in an endfire pattern. When the RF signal is inputted to the input terminal B  1282  disposed on the lower end of the second sub unit  1214 , the RF signal is inputted through the lower end of the feeding unit  1210 . In this case, the signal is radiated in a broadside pattern. According to a radiation pattern of the signal, the input terminal A  1281  may be referred to as an endfire source input and the input terminal B  1282  may be referred to as a broadside source input. A detailed example of the signal radiation pattern according to the RF signal input to the input terminal A  1281  or the input terminal B  1282  is as shown in  FIGS. 13 and 14 , which will be described below. 
         [0076]    Referring to view (c) of  FIG. 12B , a signal may be inputted to an input terminal C  1283  or an input terminal D  1284  to be radiated in the endfire pattern. In other words, the signal may be inputted to the input terminal C  1283  disposed on the middle of the side surface of the first sub unit  1212  of the feeding unit  1210 . Alternatively, the signal may be inputted to the input terminal D  1284  disposed on the lower end of the side surface of the first sub unit  1212  of the feeding unit  1210 . In addition, a signal may be inputted to an input terminal E  1285  to be radiated in the broadside pattern. Similarly to the input terminal B  1282 , the input terminal E  1285  may be disposed on the lower end of the second sub unit  1214 , but the signal bypasses. That is, the signal inputted to the input terminal E  1285  is initially generated on the side surface of the antenna, but bypasses inside the antenna, thereby being inputted to the lower end of the second sub unit  1214  of the feeding unit  1210 . 
         [0077]    Views (d) and (e) of  FIG. 12B  illustrate other arrangements of the first sub unit  1212  and the second sub unit  1214 . As shown in view (d) of  FIG. 12B , the first sub unit  1212  and the second sub unit  1214  may be disposed on the same location on the z-axis. In addition, as shown in view (e) of  FIG. 12B , the first sub unit  1212  may be disposed to be lower than the second sub unit  1214  on the z-axis. 
         [0078]      FIG. 13  illustrates an example of a radiation characteristic according to a feeding direction of an antenna in a transmission device according to an exemplary embodiment of the present invention. View (a) of  FIG. 13  illustrates a current direction on the feeding unit  1310 , and view (b) illustrates an example of a signal radiation pattern according to the current direction as shown in view (a). When the RF signal is inputted to the input terminal A  1281 , the current flows in the vertical direction, that is, in the z-axis direction, as shown in view (a). In this case, the radiation pattern has directivity in the horizontal direction as shown in view (b). In the case of  FIG. 13 , a maximum gain of about 3 dBi or higher may be obtained. 
         [0079]      FIG. 14  illustrates another example of a radiation characteristic according to a feeding direction of the antenna in the transmission device according to an exemplary embodiment of the present invention. In  FIG. 14 , view (a) illustrates a current direction on a feeding unit  1410  and view (b) illustrates an example of a signal radiation pattern according to the current direction as shown in view (a). When the RF signal is inputted to the input terminal B  1282 , the current flows in the horizontal direction, that is, in the x-axis direction, as shown in view (a). In this case, the radiation pattern has directivity in the vertical direction as shown in view (b). In the case of  FIG. 14 , a maximum gain of about 4.56 dBi or higher may be obtained. 
         [0080]    The antenna according to various exemplary embodiments of the present invention as described above includes the feeding unit and the guiding unit. According to another exemplary embodiment of the present invention, a plurality of antenna including the feeding unit and the guiding unit described above are arranged, so that the transmission device can support beam steering. For example, a detailed example of a radiation characteristic according to the number of antennas is as shown in  FIGS. 15 and 16 . 
         [0081]      FIG. 15  illustrates an example of a radiation characteristic when two antennas are used in the transmission device according to an exemplary embodiment of the present invention. Referring to  FIG. 15 , two antennas are arranged in parallel. As a result of conducting a simulation, in the case of  FIG. 15 , a maximum gain of 9.7 dBi appears within a range of a radiation angle from 60° to 70°, and a maximum gain of 6.6 dBi appears at a radiation angle of 90°. 
         [0082]      FIG. 16  illustrates an example of a radiation characteristic when four antennas are used in the transmission device according to an exemplary embodiment of the present invention. Referring to  FIG. 16 , four antennas are arranged in parallel. As a result of conducting a simulation, in the case of  FIG. 16 , a maximum gain of 11.7 dBi appears within a range of a radiation angle from 60° to 70°, and a maximum gain of 8.4 dBi appears at a radiation angle of 90°. 
         [0083]    The direction of a beam in the horizontal direction may be controlled by using a plurality of antennas.  FIG. 17  illustrates examples of beam steering which uses a plurality of antennas in the transmission device according to an exemplary embodiment of the present invention. Views (a), (b), (c) and (d) of  FIG. 17  illustrate radiation patterns having different directivity on the x-y plane. When the direction of the y-axis is defined as 0°, view (a) illustrates a horizontal radiation angle of 0°, view (b) illustrates a horizontal radiation angle of −15°, view (c) illustrates a horizontal radiation angle of −30°, and view (d) illustrates a horizontal radiation angle of −45°. In the case of  FIG. 17 , according to a result of conducting a simulation, a gain may be obtained according to a vertical radiation angle as follows: in the case of view (a), a gain of 12.2 dBi is obtained at the vertical radiation angle of 65° and a gain of 8.9 dBi is obtained at the vertical radiation angle of 90°, in the case of view (b), a gain of 11.87 dBi is obtained at the vertical radiation angle of 65° and a gain of 8.7 dBi is obtained at the vertical radiation angle of 90°, in the case of view (c), a gain of 11.3 dBi is obtained at the vertical radiation angle of 65° and a gain of 8.3 dBi is obtained at the vertical radiation angle of 90°, and, in the case of view (d), a gain of 9.7 dBi is obtained at the vertical radiation angle of 65° and a gain of 8.1 dBi is obtained at the vertical radiation angle of 90°. 
         [0084]    In the antenna according to the exemplary embodiment of the present invention described above, the guiding unit includes a plurality of guide elements. According to the above-described exemplary embodiments, the guide elements are arranged in a straight line. However, according to another exemplary embodiment of the present invention, the guide elements may be arranged in a nonlinear fashion. For example, the guide elements may be arranged in a circular fashion, a curved line fashion, and a segmental fashion. An example of the nonlinear arrangement is as illustrated in  FIG. 18 . 
         [0085]      FIG. 18  illustrates a configuration example of an antenna in a transmission device according to another exemplary embodiment of the present invention. In  FIG. 18 , view (a) illustrates a perspective view and view (b) illustrates a plane view. Referring to  FIG. 18 , the antenna includes a feeding unit  1810  and a guiding unit  1820 . Guide elements of the guiding unit  1820  are arranged in a nonlinear fashion unlike in the case of  FIG. 3 . In the case of  FIG. 18 , the guiding unit  1820  is configured in a linear fashion within a predetermined range from the feeding unit  1810 . However, according to another exemplary embodiment of the present invention, the entirety of the guiding unit  1820  may be configured in a nonlinear fashion. In addition, in the case of  FIG. 18 , the guiding unit  1820  may have a curved shape including a bending part in one direction. However, according to another exemplary embodiment of the present invention, the guiding unit  1820  may have a complex curved shape including two or more bending parts. 
         [0086]      FIG. 19  illustrates a configuration example of an antenna in a transmission device according to another exemplary embodiment of the present invention.  FIG. 19  illustrates an example of a configuration of antennas in which linear arrangement and nonlinear arrangement of guide elements are mixed.  FIG. 19  illustrates seven antennas. However, according to another exemplary embodiment of the present invention, six or less or eight or more antennas may be configured in a similar fashion. 
         [0087]    Referring to  FIG. 19 , a first antenna includes a feeding unit  1910 - 1  and a guiding unit  1920 - 1  which includes guide elements arranged in a linear fashion. A second antenna includes a feeding unit  1910 - 2  and a guiding unit  1920 - 2  which includes guide elements arranged in a nonlinear fashion, specifically, in rightward bent fashion. A third antenna includes a feeding unit  1910 - 3  and a guiding unit  1920 - 3  which includes guide elements arranged in a nonlinear fashion, specifically, in a leftward bent fashion. Herein, the guiding unit  1920 - 2  and the guiding unit  1920 - 3  have the same curvature. A fourth antenna includes a feeding unit  1910 - 4  and a guiding unit  1920 - 4  which includes guide elements arranged in a nonlinear fashion, specifically, in a rightward bent fashion. A fifth antenna includes a feeding unit  1910 - 5  and a guiding unit  1920 - 5  which includes guide elements arranged in a nonlinear fashion, specifically, in a leftward bent fashion. Herein, the guiding unit  1920 - 4  and the guiding unit  1920 - 5  have the same curvature, and the curvature of the guiding unit  1920 - 4  and the guiding unit  1920 - 5  is greater than the curvature of the guiding unit  1920 - 2  and the guiding unit  1920 - 3 . A sixth antenna includes a feeding unit  1910 - 6  and a guiding unit  1920 - 6  which includes guide elements arranged in a nonlinear fashion, specifically, in a rightward bent fashion. A seventh antenna includes a feeding unit  1910 - 7  and a guiding unit  1920 - 7  which includes guide elements arranged in a nonlinear fashion, specifically, in a leftward bent fashion. Herein, the guiding unit  1920 - 6  and the guiding unit  1920 - 7  have the same curvature, and the curvature of the guiding unit  1920 - 6  and the guiding unit  1920 - 7  is greater than the curvature of the guiding unit  1920 - 4  and the guiding unit  1920 - 5 . 
         [0088]      FIG. 20  illustrates a signal transmission procedure in the transmission device according to an exemplary embodiment of the present invention.  FIG. 20  illustrates an example of a signal transmission method using the antenna according to the above-described various exemplary embodiments. To achieve this, the transmission device may further include at least one processor to control signal transmission. 
         [0089]    Referring to  FIG. 20 , the transmission device determines a radiation pattern in step  2001 . The radiation pattern includes at least one of a direction of a beam, a size of a beam, and a beam width. That is, the transmission device determines at least one of the direction of the beam, the size of the beam, and the beam width. For example, the transmission device may determine the radiation pattern for beam sweeping for beam training, or determine the radiation pattern to fix a beam in an optimum beam direction, which is determined through the beam training. 
         [0090]    Next, the transmission device proceeds to step  2003  to determine whether to feed a current and a feeding direction. The transmission device includes a plurality of antennas, that is, an antenna array. In this case, the transmission device may control a beam width by controlling the number of antennas to feed a current. In addition, as described above with reference to  FIGS. 12A and 12B , a signal is radiated in an endfire pattern or a broadside pattern according to a feeding direction. That is, the transmission device may determine the feeding direction according to the radiation pattern which is determined in step S 2001 . That is, the feeding direction is related to a beam direction. 
         [0091]    Next, the transmission device proceeds to step  2005  to determine a phase for each antenna. That is, the transmission device determines at least one phase for beamforming with respect to the at least one antenna to feed the current. Accordingly, by determining the phase for each antenna, the transmission device may control the direction of the beam, specifically, the angle of the beam. Accordingly, the transmission device determines the phase for each antenna according to the radiation pattern which is determined in step  2001 . 
         [0092]    Thereafter, the transmission device proceeds to step  2007  to output a signal. That is, the transmission device feeds a current to the at least one antenna which is selected in step  2003 . In this case, the transmission device feeds the current in the feeding direction which is determined in step  2003 . In addition, the transmission device applies the phase which is determined in step  2005  to the signal which is fed to each antenna. Accordingly, the transmission device may transmit the signal in the radiation pattern which is determined in step  2001 . That is, the transmission device adjusts the radiation pattern of the signal through the guiding unit which is formed of a plurality of elements physically spaced from one another. 
         [0093]      FIG. 21  illustrates an example of utilization of the antenna according to an exemplary embodiment of the present invention.  FIG. 21  illustrates a case in which the antenna according to an exemplary embodiment of the present invention is applied to ultrasonic examination equipment. As shown in  FIG. 21 , the antenna may be utilized to minimize interruption which may occur between frames forming an ultrasonic image which is transceived between a wireless probe  2180  and an ultrasonic diagnosis device  2190 . 
         [0094]    In a high frequency band which has strong directivity, the directionality of signal radiation greatly influences a signal quality. Referring to  FIG. 21 , a signal transceiving direction between the wireless probe  2180  and the ultrasonic diagnosis device  2190  may be divided into a line of sight (LOS) direction  2194  and a non line of sight (NLOS) direction  2192 . Referring to  FIG. 21 , the wireless probe  2180  is normally used with the ultrasonic diagnosis device  2190  being placed in a direction perpendicular to a major axis (for example, the x-axis). Accordingly, in order to transceive signals in the LOS direction  2194 , a signal should be radiated in a direction perpendicular to the major axis (for example, the x-axis) of the wireless probe  2180 . In addition, in order to transceive signals in the NLOS direction  2194 , a signal should be radiated in a direction similar to the major axis (for example, the x-axis) of the wireless probe  2180 . Herein, the NLOS refers to a path through which signals are reflected on other objects (for example, a wall, a ceiling, or the like) and are transceived. 
         [0095]      FIG. 22  illustrates radiation patterns of a wireless probe to which the antenna according to an exemplary embodiment of the present invention is applied.  FIG. 22  illustrates examples of signal radiation patterns for communication in the LOS direction  2194  and the NLOS direction  2192  in the wireless probe  2180 . 
         [0096]    Referring to view (a) of  FIG. 22 , a signal is radiated in the direction of the major axis (for example, the z-axis) of the wireless probe  2180  to perform communication in the NLOS direction  2192 . To achieve this, a signal for radiation in the broadside direction may be inputted to the feeding unit of the antenna. Referring to view (b) of  FIG. 22 , a signal is radiated in the direction perpendicular to the major axis (for example, the z-axis) of the wireless probe  2180  to perform communication in the LOS direction  2194 . To achieve this, a signal for radiation in the endfire direction may be inputted to the feeding unit of the antenna. In this case, it is preferable that the antenna is mounted on the uppermost end of the wireless probe  2180  to prevent signal radiation from being interfered by user&#39;s hand in consideration of a normal using method of the wireless probe  2180 . 
         [0097]      FIG. 23  illustrates arrangement of antennas installed in a wireless probe according to an exemplary embodiment of the present invention.  FIG. 23  illustrates a circuit including an RFIC  2304  and a plurality of antennas  2308 . The circuit shown in  FIG. 23  may be disposed at the upper end of the wireless probe  2180 . 
         [0098]    Referring to view (a) of  FIG. 23 , the circuit including the RFIC  2304  and antennas  2308 - 1  to  2308 - 16  may be disposed perpendicular to the major axis (for example, the z-axis) of the wireless probe  2180 . This arrangement makes it possible to transceive signals in the broadside and endfire directions. Specifically, as shown in view (a) of  FIG. 23 , the antennas  2308 - 1  to  2308 - 16  may be divided into two antenna groups which are arranged in different directions with reference to the RFIC  2304 . The antenna groups arranged in different directions may be selectively used according to a relative location relationship between the ultrasonic diagnosis device  2190  and the wireless probe  2180 . For example, when the ultrasonic diagnosis device  2190  is located on the left of the user who uses the wireless probe  2180  with user&#39;s right hand, the antenna group which is close to the ultrasonic diagnosis device  2190  may be used. 
         [0099]    Referring to view (b) of  FIG. 23 , the circuit including the RFIC  2304  and antennas  2308 - 1  to  2308 - 32  may be disposed perpendicular to the major axis (for example, the z-axis) of the wireless probe  2180 . This arrangement makes it possible to transceive signals in the broadside and endfire directions. Specifically, the antennas  2308 - 1  to  2308 - 32  may be divided into four antenna groups which are arranged in different directions with reference to the RFIC  2304 . The antenna groups arranged in different directions may be selectively used according to a relative location relationship between the ultrasonic diagnosis device  2190  and the wireless probe  2180 . For example, the antenna group which is close to the ultrasonic diagnosis device  2190  may be used. 
         [0100]    In  FIG. 23 , view (a) illustrates an example of two antenna groups for two directions, and view (b) illustrates an example of four antenna groups for four directions. However, the present invention is not limited to two or four directions. That is, according to another exemplary embodiment of the present invention, only one direction may be considered or three directions may be considered, or an antenna structure for five or more directions may be included in the wireless probe  2180 . 
         [0101]      FIG. 24  illustrates arrangement of antennas installed in a wireless probe with a heat sink plate according to an exemplary embodiment of the present invention.  FIG. 24  illustrates a circuit including an RFIC  2404  and a plurality of antennas  2408 - 1  to  2408 - 16 . The circuit shown in  FIG. 24  may be located at the upper end of the wireless probe  2180 . Referring to  FIG. 24 , in addition to the RFIC  2404  and the antennas  2408 - 1  to  2408 - 16 , a heat sink plate  2412  may be installed. The heat sink plate  2412  performs a function of discharging heat generated in the RFIC  2404  and the antennas  2408 - 1  to  2408 - 16  to the outside.  FIG. 24  illustrates a case in which the heat sink plate  2412  is added to the structure shown in view (a) of  FIG. 23 . However, the heat sink plate  2412  may be added to other antenna structures (for example, view (b) of  FIG. 23 ). 
         [0102]    In the above-described exemplary embodiments of the present invention, the components included in the present invention are expressed in singular forms or plural forms according to a detailed exemplary embodiment. However, the singular or plural expression is appropriately selected according to a suggested situation for the convenience of explanation, and the present invention is not limited to the singular or plural components. A component expressed in the plural form may be configured as a single component or a component expressed in the singular form may be configured as a plurality of component. 
         [0103]    While specific embodiments have been described in the detailed descriptions of the present invention, various changes can be made within a limit without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to and defined by the above-described exemplary embodiments, and should be defined not only by the appended claims but also by the equivalents to the scopes of the claims.