CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2014-0009556 filed on Jan. 27, 2014, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    The present disclosure relates to a circuit board, and more particularly, to a circuit board capable of internally transferring a signal through radio communications. 
         [0003]    In a printed circuit board or a multilayer ceramic board formed by stacking a plurality of ceramic sheets according to the related art, a wiring pattern is formed on upper and lower surfaces or in an internal portion of the board. In addition, a conductive via is mainly used in order to electrically connect these wiring patterns to each other. 
         [0004]    Such a board according to the related art has mainly been used in a device using a frequency in an ultra-high frequency (UHF) band or a frequency lower than UHF. However, as frequency bands utilized by electronic devices are increased, in the case of using a conductive via to transfer a signal in the board according to the related art, signal loss may increase. Such signal loss may be further intensified in a super high frequency (SHF)/extremely high frequency (EHF) band, commonly seen as a next-generation communications band. 
       RELATED ART DOCUMENT 
       [0005]    (Patent Document 1) Korean Patent Laid-Open Publication No. 2013-0056570 
       SUMMARY 
       [0006]    An aspect of the present disclosure may provide a circuit board in which a via according to the related art is omitted and in which a signal may be transferred within the board through radio communications. 
         [0007]    According to an aspect of the present disclosure, a circuit board may include: an insulation layer; a first signal transfer circuit formed of a circuit pattern on one surface of the insulation layer; and a second signal transfer circuit formed of a circuit pattern on the other surface of the insulation layer and wirelessly transferring a signal through resonance with the first signal transfer circuit; wherein the first and second signal transfer circuits transfer the signal in a super high frequency (SHF) band or an extremely high frequency (EHF) band. 
         [0008]    Each of the first and second signal transfer circuits may include: a wiring pattern; a resonance part connected to one end of the wiring pattern; a ground part disposed so as to be spaced apart from the resonance part; and a connection part electrically connecting the resonance part and the ground part to each other. 
         [0009]    The resonance parts of the first and second signal transfer circuits may be disposed in positions corresponding to each other. 
         [0010]    The connection parts of the first and second signal transfer circuits may be disposed in positions corresponding to each other. 
         [0011]    The resonance parts of the first and second signal transfer circuits may be formed of planar patterns. 
         [0012]    The connection parts of the first and second signal transfer circuits may be formed of linear patterns. 
         [0013]    Characteristics of the resonance may be determined by inductance L 1  of the resonance part of the first signal transfer circuit, inductance L 2  of the resonance part of the second signal transfer circuit, and parasitic capacitance C 0  generated between the resonance parts of the first and second signal transfer circuits. 
         [0014]    A bandwidth and a return loss of the signal may be determined by inductance L 3  of the connection part of the first signal transfer circuit, inductance L 4  of the connection part of the second signal transfer circuit, capacitance C 3  generated between the resonance part and the ground part of the first signal transfer circuit, and capacitance C 4  generated between the resonance part and the ground part of the second signal transfer circuit. 
         [0015]    L 3  and L 4  may be formed to be 3 to 5 times L 1  or L 2  in order to decrease the return loss of the signal. 
         [0016]    C 3  and C 4  may be formed to be 1/30 to 1/10 times C 0  in order to decrease the return loss of the signal. 
         [0017]    C 3  and C 4  may be formed to be 1 to 2 times C 0  in order to expand a frequency bandwidth of the signal. 
         [0018]    The circuit board may further include at least one electronic element connected to the other end of the wiring pattern. 
         [0019]    The circuit board may further include: at least one antenna connected to the other end of the wiring pattern of the first signal transfer circuit; and at least one electronic element connected to the other end of the wiring pattern of the second signal transfer circuit. 
         [0020]    The first and second signal transfer circuits may be disposed on the insulation layer in plural. 
         [0021]    The insulation layer may be a multilayer board in which at least one circuit pattern is formed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0022]    The above and other aspects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0023]      FIG. 1  is a cross-sectional diagram schematically illustrating a circuit board according to an exemplary embodiment of the present disclosure; 
           [0024]      FIG. 2  is an exploded perspective diagram of  FIG. 1 ; 
           [0025]      FIG. 3  is a circuit diagram schematically illustrating an equivalent circuit of the circuit board shown in  FIG. 2 ; 
           [0026]      FIG. 4  is a graph illustrating a result obtained by measuring a return loss of the circuit board according to an exemplary embodiment of the present disclosure; 
           [0027]      FIG. 5  is a graph illustrating a result obtained by measuring a return loss of the circuit board according to another exemplary embodiment of the present disclosure; 
           [0028]      FIGS. 6 and 7  are graphs illustrating results obtained by changing a value of C 3  and C 4  in the circuit board of  FIG. 5  and measuring a return loss of the circuit board; 
           [0029]      FIGS. 8 and 9  are graphs comparing signal transfer characteristics of the circuit board according to the present exemplary embodiment and a circuit board according to the related art with each other; and 
           [0030]      FIG. 10  is a plan diagram schematically illustrating a circuit board according to another exemplary embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
         [0032]      FIG. 1  is a cross-sectional diagram schematically illustrating a circuit board according to an exemplary embodiment of the present disclosure, and  FIG. 2  is an exploded perspective diagram of  FIG. 1 . 
         [0033]    Referring to  FIGS. 1 and 2 , the circuit board  100  according to an exemplary embodiment of the present disclosure may include an insulation layer  101 , signal transfer circuits  110  and  120 , and a plurality of elements  130  and  140 . 
         [0034]    The insulation layer  101  may be a board on which an electronic element such as an active element or a passive element is mounted on at least one surface thereof. However, the insulation layer is not limited thereto, but may be a single insulating material layer or a plurality of insulating material layers stacked in the board. 
         [0035]    In the case in which the insulation layer  101  is formed of a board, various kinds of boards (for example, a ceramic board, a printed circuit board, a flexible board, or the like) well known in the art may be used as the board. In addition, both surfaces of the board may be provided with mounting electrodes for mounting electronic components thereon or circuit patterns electrically interconnecting the mounting electrodes. 
         [0036]    The board may be a multilayer board formed of a plurality of layers. In this case, a circuit pattern may be formed between each of the layers of the board. 
         [0037]    Further, a cavity (not shown) in which electronic elements may be embedded may be formed in the board according to the present exemplary embodiment. 
         [0038]    The signal transfer circuits  110  and  120  may be formed on both surfaces of the insulation layer  101 . The signal transfer circuits  110  and  120  may be provided in a form of a circuit pattern and formed of a metal having excellent conductivity such as Cu, Ni, Al, Ag, Au, and the like. 
         [0039]    The signal transfer circuits  110  and  120  may include a first signal transfer circuit  110  formed on one surface of the insulation layer  101  and a second signal transfer circuit  120  formed on the other surface thereof, and the first and second signal transfer circuits  110  and  120  may include wiring pattern parts  117  and  127 , resonance parts  111  and  121 , connection parts  113  and  123 , and ground parts  115  and  125 , respectively. 
         [0040]    The wiring pattern parts  117  and  127  may be formed as portions of the circuit pattern formed on the insulation layer  101  and include a first wiring pattern  117  formed on one surface of the insulation layer  101  and a second wiring pattern  127  formed on the other surface thereof. 
         [0041]    The first and second wiring patterns  117  and  127  may be formed in a manner in which they face each other based on the insulation layer  101 , but are not limited thereto. 
         [0042]    Resonance parts  111  and  121  to be described below may be connected to one ends of the wring pattern parts  117  and  127 , and at least one electronic element  130  and  140  may be connected to the other ends thereof. Here, the electronic element may include an element  130  transferring a signal and an antenna  140  receiving the signal transferred from the element  130  to radiate the transferred signal to the outside. Here, the element  130  may be a radio frequency integrated circuit (RFIC), but is not limited thereto. 
         [0043]    In addition, the case in which the antenna  140  is connected to the first wiring pattern  117  and the element  130  is connected to the second wiring pattern  127  is described by way of example in the present exemplary embodiment. However, the configuration of the present disclosure is not limited thereto, but may be variously modified when needed. For example, the element rather than the antenna may be connected to the first wiring pattern  117 . 
         [0044]    The resonance parts  111  and  121  may include a first resonance part  111  formed on one surface of the insulation layer  101  and a second resonance part  121  formed on the other surface thereof. 
         [0045]    The first and second resonance parts  111  and  121  may be disposed on both surfaces of the insulation layer  101 , respectively, and formed in a shape in which the first and second resonance parts  111  and  121  face each other, based on the insulation layer  101 , similarly to the first and second wiring patterns  117  and  127 . 
         [0046]    The first and second resonance parts  111  and  121  may be formed of a flat planar circuit patterns having a predetermined area and electrically connected to the first and second wiring patterns  117  and  127 , respectively. 
         [0047]    That is, the first resonance part  111  may be disposed at a distal end of the first wiring pattern  117  to thereby be electrically connected to the first wiring pattern  117 , and the second resonance part  121  may be disposed at a distal end of the second wiring pattern  127  to thereby be electrically connected to the second wiring pattern  127 . 
         [0048]    Further, in the circuit board  100  according to the present exemplary embodiment, a signal is transferred through resonance of the first and second resonance parts  111  and  121 . Therefore, the first and second resonance parts  111  and  121  may be formed to have the same shape as each other and be disposed in the manner in which they face each other based on the insulation layer  101 . However, the first and second resonance parts  111  and  121  are not limited thereto, but may be formed in a different shape when needed. 
         [0049]    Meanwhile, although the case in which the first and second resonance parts  111  and  121  are formed of a tetragonal circuit pattern is described by way of example in the present exemplary embodiment, the present disclosure is not limited thereto. That is, the first and second resonance parts  111  and  121  may have various shapes such as a polygonal shape, a circular shape, or the like, when needed. 
         [0050]    The connection parts  113  and  123  may electrically connect the resonance parts  111  and  121  and ground parts  115  and  125  to be described below to each other. To this end, the connection parts  113  and  123  may include a first connection part  113  connecting the first resonance part  111  and a first ground part  115  to each other and a second connection part  123  connecting the second resonance part  121  and a second ground part  125 . 
         [0051]    The connection parts  113  and  123  may be provided in a form of a circuit pattern formed on the insulation layer  101 , similarly to the wiring pattern parts  117  and  127 , and be formed of a linear pattern having a width narrower than that of the resonance parts  111  and  121 . 
         [0052]    The ground parts  115  and  125  may be provided in a form of a circuit pattern and formed in a linear shape similarly to the wiring pattern parts  117  and  127  or a plane shape similarly to the resonance parts  111  and  121 . 
         [0053]    The ground parts  115  and  125  may be electrically connected to the resonance parts  111  and  121  via the connection parts  113  and  123 . Therefore, the ground parts  115  and  125  may include the first ground part  115  electrically connected to the first resonance part  111  and the second ground part  125  electrically connected to the second resonance part  121 . In addition, the first and second ground parts  115  and  125  may be electrically connected to each other when needed. 
         [0054]    The circuit board  100  according to the present exemplary embodiment configured as described above may include the first and second resonance parts  111  and  121  disposed in two circuit pattern layers spaced apart from each other by the insulation layer  101  so as to face each other. In addition, the circuit board  100  may include the connection parts  113  and  123  connecting the resonance parts  111  and  121  and the ground parts  115  and  125 , respectively. 
         [0055]    Here, the signal in the circuit board  100  may be transferred through resonance of the first and second resonance parts  111  and  121 . Therefore, the first and second resonance parts  111  and  121  may be disposed so as to be spaced apart from each other by a distance at which resonance may occur in a SHF/EHF band. 
         [0056]    That is, the insulation layer  101  according to the present exemplary embodiment may have a thickness and be formed of a material such that resonance may occur between the first and second resonance parts  111  and  121  in the SHF/EHF band. 
         [0057]    The circuit board  100  according to the present exemplary embodiment configured as described above may have high signal transfer efficiency in the SHF/EHF band as compared to a circuit board using a via according to the related art. 
         [0058]      FIGS. 8 and 9  are graphs comparing signal transfer characteristics of the circuit board according to the present exemplary embodiment and a circuit board according to the related art with each other. Here,  FIG. 8  is a graph comparing return loss, and  FIG. 9  is a graph illustrating comparing insertion loss. Further, in the case in which a signal was transferred in a 60 GHz band, the measurement was preformed, and the results were shown. 
         [0059]    Referring to  FIG. 8 , it was measured that in a circuit board P 2  according to the present exemplary embodiment of the present disclosure, the return loss was significantly low as compared to a circuit board P 1  using a via according to the related art, and particularly, the return loss was −20 dB or less in the vicinity of 60 GHz. 
         [0060]    On the contrary, in the circuit board P 1  according to the related art, the measured return loss was entirely about −1 dB, such that it may be appreciated that the return loss was significantly high, and it was not easy to substantially transfer a signal in the SHF/EHF band. 
         [0061]    In addition, referring to  FIG. 9 , the circuit board P 2  according to the present exemplary embodiment, it was measured that the insertion loss was higher than about −1 dB. Further, it was measured that in the circuit board P 1  using a via according to the related art, the insertion loss was lower than about −7 dB. Therefore, it may be appreciated that in the circuit board P 2  according to the present exemplary embodiment, attenuation of a transfer signal was low in the SHF/EHF band as compared to the circuit board P 1  according to the related art. 
         [0062]    As described above, it may be appreciated that in the circuit board according to the present exemplary embodiment, the signal transfer characteristics in the SHF/EHF band were significantly improved as compared to the circuit board using a via according to the related art. 
         [0063]    Meanwhile, the connection parts  113  and  123  of the circuit board according to the present exemplary embodiment may be used to determine a signal transfer frequency and improve reflection characteristics in addition to a function of electrically connecting the resonance parts  111  and  121  and the ground parts  115  and  125  to each other. 
         [0064]      FIG. 3  is a circuit diagram schematically illustrating an equivalent circuit of the circuit board shown in  FIG. 2 . 
         [0065]    Here, L 1  and L 2  shown in  FIG. 3  are structural inductances of the first and second resonance parts  111  and  121 , respectively, and C 1  and C 2  are parasitic capacitances (hereinafter, collectively referred to as C 0 ) that do not structurally exist but are generated by electrical coupling between two surfaces since the first and second resonance parts  111  and  121  are disposed so as to face each other. 
         [0066]    The circuit configured to include L 1 , L 2 , C 1 , and C 2  may have a basic structure capable of transferring a signal using resonance characteristics. 
         [0067]    In addition, L 3  and L 4  are inductances of the first and second connection parts  113  and  123 , respectively. Further, C 3  is parasitic capacitance generated between the first resonance part  111  and the first ground part  115 , and C 4  is parasitic capacitance generated between the second resonance part  121  and the second ground part  125 . Here, C 3  and C 4  may be formed by side surfaces of the resonance part  111  and  121  and the ground parts  115  and  125  facing each other. 
         [0068]    The circuit configured to include L 3 , L 4 , C 3 , and L 4  may be used to determine a bandwidth of the transfer signal and reflection characteristics and adjust the transfer frequency. 
         [0069]    The connection parts  113  and  123  according to the present exemplary embodiment may be applied to decrease reflectivity of a signal transferred to the elements  130  and  140  to increase signal transfer efficiency in the vicinity of a resonance frequency band in addition to the function of electrically connecting the resonance parts  111  and  121  and the ground parts  115  and  125  to each other as described above. 
         [0070]    To this end, inductances L 3  and L 4  of the connection parts  113  and  123  may be formed to be three to five times L 1  or L 2 , equal to inductance of the resonance part  111  or  121 . Here, a specific value (or inductance) of L 3  and L 4  may be determined depending on a bandwidth of a communications system transferring signals. 
         [0071]    In the case in which L 3  and L 4  are formed to be less than three times L 1  or L 2 , impedance by the L 3  and L 4  may be decreased, such that leakage of the signal to the ground parts  115  and  125  may be increased. Therefore, the signal transfer efficiency may be rather decreased. 
         [0072]    Further, in the case in which L 3  and L 4  are formed to be more than 5 times L 1  or L 2 , impedance by the L 3  and L 4  may be increased, an effect of improving the signal transfer efficiency may be insignificant. 
         [0073]    Therefore, in the connection parts  113  and  123  according to the present exemplary embodiment, in the case in which L 3  and L 4  are formed to be three to five times L 1  or L 2 , equal to inductance of the resonance part  111  or  121 , the signal transfer efficiency may be increased. 
         [0074]    Further, in the circuit board  100  according to the present exemplary embodiment, the signal transfer efficiency may be increased through a value (or capacity) of C 3  and C 4 , and additionally, a frequency bandwidth may be expanded. 
         [0075]    In detail, during a manufacturing process of the circuit board  100 , the value of C 3  and C 4  is formed to be in a range of 1/30 to 1/10 times C 0  (C 1  or C 2 ), such that the signal transfer efficiency may be increased. 
         [0076]    Here, in the case in which the value of C 3  and C 4  is formed to be more than 1/10 times C 0 , since impedance may be decreased, the signal may be leaked to the ground part  115  through C 3  and C 4 , such that signal transfer efficiency may be decreased. 
         [0077]    Further, in the case in which the value of C 3  and C 4  is formed to be less than 1/30 times C 0 , since impedance may be increased, the effect of improving the signal transfer efficiency may be insignificant. 
         [0078]    Therefore, in the circuit board  100  according to the present exemplary embodiment, in the case in which the value of C 3  and C 4  is formed to be in the range of 1/30 to 1/10 times C 0 , the signal transfer efficiency may be increased. 
         [0079]    More specifically, in the circuit board  100  according to the present exemplary embodiment, a value of L 3  and L 4  is formed to be three to five times L 1  or L 2 , or the value of C 3  and C 4  is formed to be in the range of 1/30 to 1/10 times C 0 , such that the signal transfer efficiency may be increased. 
         [0080]      FIG. 4  is a graph illustrating a result obtained by measuring a return loss of the circuit board according to an exemplary embodiment of the present disclosure. 
         [0081]    The graph of  FIG. 4  shows a return loss measured in a circuit board  100  in which C 1  and C 2  and L 1  and L 2  were set to 0.02 pF and 0.175 nH, respectively, in order to transfer a signal in a 60 GHz band, and L 3  and L 4  and C 3  and C 4  were set to 0.7 nH and 0.001 pF, respectively, in a communications system having a bandwidth less than 10 GHz. 
         [0082]    In this case, it may be appreciated that the return loss was further decreased in the resonance frequency band when being compared with the graph of  FIG. 8 . Therefore, it may be appreciated that the signal transfer efficiency was increased. 
         [0083]    Meanwhile, in the present exemplary embodiment, C 1  and C 2  and L 1  and L 2  are not limited to the above-mentioned values, but may be set to various values in order to determine a basic resonance frequency. Further, in the case in which L 3 , L 4 , C 3 , and C 4  may also be set to various values as long as the values are in the above-mentioned range. 
         [0084]    Further, in the circuit board  100  according to the present exemplary embodiment, in the case in which the value of C 3  and C 4  is in a range of 1 to 2 times C 0 , a resonance frequency of the transferred signal may be added as shown in  FIG. 5 . Therefore, in this case, a frequency bandwidth of the entire transfer signal may be expanded. 
         [0085]      FIG. 5  is a graph illustrating a result obtained by measuring a return loss of the circuit board according to another exemplary embodiment of the present disclosure. The graph of  FIG. 5  shows a return loss measured in a circuit board  100  in which C 1  and C 2  and L 1  and L 2  were set to 0.02 pF and 0.175 nH, respectively, in order to transfer a signal in a 60 GHz band, and L 3  and L 4  and C 3  and C 4  were set to 0.7 nH and 0.03 pF, respectively, in order to expand a bandwidth to 10 GHz or more. 
         [0086]    In this case, when being compared with the graph shown in  FIG. 4 , it may be confirmed that the resonance frequency was additionally formed at a 80 GHz band, such that the frequency bandwidth was expanded. 
         [0087]      FIGS. 6 and 7  are graphs illustrating results obtained by changing the value of C 3  and C 4  in the circuit board of  FIG. 5  and measuring a return loss of the circuit board. Here,  FIG. 6  is a graph illustrating a result obtained by setting C 3  and C 4  to 0.019 pF, which is less than one time of C 0  (0.02 pF), and measuring the return loss, and  FIG. 7  is a graph illustrating a result obtained by setting C 3  and C 4  to 0.042 pF, which is more than two times C 0  (0.02 pF), and measuring the return loss. 
         [0088]    In the case in which the value of C 3  and C 4  is less than C 0 , since the added resonance frequency may be significantly spaced apart from the basic resonance frequency formed by L 1 , L 2 , C 1 , and C 2  as shown in  FIG. 6 , it may be difficult to use the added resonance frequency, such that it may be substantially difficult to expand the frequency bandwidth. 
         [0089]    Further, in the case in which the value of C 3  and C 4  is formed to be more than 2 times C 0 , the added resonance frequency hinders resonance of the basic resonance frequency as shown in  FIG. 7 , such that the reflection characteristics may be rather deteriorated. 
         [0090]    Therefore, it may be appreciated that in the circuit board  100  according to the present exemplary embodiment, in the case in which the value of C 3  and C 4  is 1 to 2 times C 0 , the frequency bandwidth may be more effectively expanded. 
         [0091]    Meanwhile, in the case in which the value of C 3  and C 4  is formed to be 1 to 2 times C 0  in order to expand the frequency bandwidth, since the value of C 3  and C 4  is not in the range of 1/30 to 1/10 times C 0 , the signal transfer efficiency may not be increased. 
         [0092]    Therefore, in this case, the value of L 3  and L 4  is formed to be 3 to 5 times L 1  or L 2 , and the value of C 3  and C 4  is formed to be 1 to 2 times C 0 , such that the signal transfer efficiency may be increased, and the frequency bandwidth may be expanded. 
         [0093]    The circuit board according to the present disclosure configured as described above is not limited to the above-mentioned embodiments but may be variously modified. 
         [0094]      FIG. 10  is a plan diagram schematically illustrating a circuit board according to another exemplary embodiment of the present disclosure. 
         [0095]    Referring to  FIG. 10 , the circuit board  100  according to the present exemplary embodiment may include a plurality of first signal transfer circuits  110  configured to include a first wiring pattern  117 , a first resonance part  111 , a first connection part  113 , and a first ground part  115  on one surface of an insulation layer  101 . In addition, the first wiring patterns  117  may be connected to antennas  140 , respectively. 
         [0096]    Here, the first signal transfer circuits  110  may be electrically connected to each other so as to share a single or plurality of first ground parts  115 . 
         [0097]    Further, a plurality of second signal transfer circuits including a second wiring pattern, a second resonance part, a second connection part, and a second ground part that are not shown may be disposed on the other surface of the insulation layer  101  at positions corresponding to the first signal transfer circuit  110 , respectively. 
         [0098]    In this case, each of the signal transfer circuits may be independently operated. That is, in the circuit board  100  according to the present exemplary embodiment, various signals may be transferred independently from each other through each of the signal transfer circuits. 
         [0099]    In addition, the case in which the signal transfer circuits are disposed on both surfaces of the insulation layer, respectively, is described in the above-mentioned exemplary embodiment. However, the present disclosure is not limited thereto. 
         [0100]    For example, an insulation protective layer may be formed on the signal transfer circuit, or another insulation layer may be stacked on the signal transfer circuit. Further, the present disclosure may be variously modified. For example, if necessary, the circuit board may be configured so that a plurality of signal transfer circuits are disposed between a plurality of insulation layers forming a multilayer board to thereby transfer a signal to each other. 
         [0101]    As set forth above, in the circuit board according to exemplary embodiments of the present disclosure, the signal transfer characteristics in the SHF/EHF band may be significantly improved as compared to the circuit board using the via according to the related art. 
         [0102]    While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the spirit and scope of the present disclosure as defined by the appended claims.
There is provided a circuit board capable of internally transferring a signal through radio communications. The circuit board according to the present disclosure may include: an insulation layer; a first signal transfer circuit formed of a circuit pattern on one surface of the insulation layer; and a second signal transfer circuit formed of a circuit pattern on the other surface of the insulation layer and wirelessly transferring a signal through resonance with the first signal transfer circuit; wherein the first and second signal transfer circuits transfer the signal in a super high frequency (SHF) band or an extremely high frequency (EHF) band.