Patent Publication Number: US-11658372-B2

Title: Transmission line and antenna

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International Application No. PCT/JP2019/025217 filed Jun. 25, 2019, claiming priority based on Japanese Patent Application No. 2018-124480 filed Jun. 29, 2018, the entire disclosure of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a transmission line and an antenna. 
     BACKGROUND ART 
     The use of a transmission line for supplying power to an antenna or the like is known. 
     For example, Patent Document 1 discloses the use of a transmission line for supplying power to a multi-band antenna of a wireless communication device. 
     CITATION LIST 
     Patent Literature 
     
         
         [Patent Document 1] 
         WO 2014/059946 A1 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     In the embodiment in Patent Document 1, for example, the transmission line is provided in a space through which electromagnetic waves travel, and thus may affect the characteristics of the electromagnetic waves. 
     An example objective of an embodiment in the present disclosure is to provide a transmission line and an antenna that solve one of the above-mentioned problems. 
     Means for Solving the Problems 
     The transmission line according to an embodiment in the present disclosure has a frequency-selecting surface. 
     Advantageous Effects of Invention 
     According to an embodiment in the present disclosure, for example, even when a transmission line is provided in a space through which electromagnetic waves travel, the characteristics of the electromagnetic waves are not easily affected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  2    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  3    is an example of an equivalent circuit of part III in  FIG.  2   . 
         FIG.  4    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  5    is an enlarged view of part V in  FIG.  4   . 
         FIG.  6    is an example of an equivalent circuit of part V in  FIG.  4   . 
         FIG.  7    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  8    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  9    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  10    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  11    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  12    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  13    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  14    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  15    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  16    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  17    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  18    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  19    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  20    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  21    is an example of a radiation pattern of a second antenna element according to an embodiment in the present disclosure. 
         FIG.  22    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  23    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  24    is an example of an equivalent circuit of a transmission line according to an embodiment in the present disclosure. 
         FIG.  25    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
         FIG.  26    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     
    
    
     EXAMPLE EMBODIMENT 
     All of the embodiments in the present disclosure are merely exemplary, and are neither intended to exclude other examples from the present disclosure, nor intended to limit the technical scope of the inventions recited in the claims. 
     There may be some cases in which descriptions relating to combinations of embodiments in the present disclosure are partially omitted. 
     Such omissions are intended to simplify the explanation, and are neither intended to exclude such combinations from the present disclosure, nor to limit the technical scope of the inventions recited in the claims. 
     Regardless of whether or not they are omitted, all combinations of the embodiments in the present disclosure are explicitly, implicitly or inherently included in the present disclosure. 
     In other words, regardless of whether or not they are omitted, all combinations of embodiments in the present disclosure can be directly and clearly derived from the present disclosure. 
     For example, a transmission line according to an embodiment in the present disclosure may have a first frequency-selecting surface. 
       FIG.  1    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  2    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  3    is an example of an equivalent circuit of part III in  FIG.  2   . 
     For example, the transmission line according to an embodiment in the present disclosure may be a first transmission line  11 . 
     For example, the first transmission line  11  may be extended in the Y-axis direction. 
     For example, the direction of extension of the first transmission line  11  will be referred to as the Y-axis direction. 
     For example, a radial direction from the first transmission line  11  will be referred to as the X-axis direction. 
     For example, a direction orthogonal to the X-axis direction and orthogonal to the Y-axis direction will be referred to as the Z-axis direction. 
     For example, the first transmission line  11  may have a first frequency-selecting surface  111 . 
     For example, the first frequency-selecting surface  111  may be an FSS (Frequency Selective Surface). 
     For example, the FSS has a conductor, a conductor and a dielectric, or a periodic structure thereof. 
     For example, the FSS may have the function of selectively passing electromagnetic waves in a specific frequency band. 
     For example, the first frequency-selecting surface  111  may be configured so that the first transmission line  11  allows electromagnetic waves of a certain frequency to pass. 
     For example, the first transmission line  11  may be provided with a conductor  112 . 
     For example, the conductor  112  may extend in the Y-axis direction. 
     For example, the conductor  112  may be provided with a ground conductor  1122  and a core wire  1123 . 
     For example, the ground conductor  1122  may extend in the Y-axis direction. 
     For example, the core wire  1123  may extend in the Y-axis direction. 
     For example, the ground conductor  1122  may cover the outer circumference of the core wire  1123  over the entire circumference about the Y-axis direction. 
     For example, the central axis of the ground conductor  1122  extending in the Y-axis direction and the central axis of the core wire  1123  extending in the Y-axis direction may be coaxial. 
     For example, the inner circumference of the ground conductor  1122  and the outer circumference of the core wire  1123  may be electrically isolated by space, a dielectric or the like. 
     For example, a space between the inner circumference of the ground conductor  1122  and the outer circumference of the core wire  1123  may be entirely or at least partially filled with a dielectric so as to extend in the Y-axis direction. 
     For example, the first transmission line  11  may be a coaxial cable having the ground conductor  1122  as an outer conductor and the core wire  1123  as an inner conductor. 
     For example, the first frequency-selecting surface  111  may include a three-dimensional pattern  1111 . 
     For example, the first frequency-selecting surface  111  may allow electromagnetic waves having a certain frequency to pass by a combination of the surface of a ground conductor  1122  and a three-dimensional pattern  1111 . 
     For example, if the frequency of incident electromagnetic waves is a frequency that matches or is close to the resonance frequency of the first frequency-selecting surface  111 , then reradiation occurs. For this reason, when the electromagnetic waves are incident on the first frequency-selecting surface  111 , they are passed to the opposite side of the first frequency-selecting surface  111 . 
     For example, the ground conductor  1122  and the three-dimensional pattern  1111  may be combined with each other so as to form an equivalence circuit having a capacitance component C and an inductance component L as illustrated in  FIG.  3   . In this way, the ground conductor  1122  and the three-dimensional pattern  1111  can be treated as equivalent to a series circuit comprising an inductance component L and a capacitance component C. 
     For example, the three-dimensional pattern  1111  may be a combination of two metallic plates that are arranged to be close to each other so as to have a gap therebetween. 
     For example, the three-dimensional pattern  1111  may be a combination of two metallic plates that are L-shaped. 
       FIG.  4    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  5    is an enlarged view of part V in  FIG.  4   . 
       FIG.  6    is an example of an equivalent circuit of part V in  FIG.  4   . 
     For example, the first frequency-selecting surface  111  may be a surface mainly comprising a repeating structure of a metallic pattern, and may have a surface structure that allows electromagnetic waves of a certain frequency to pass. 
     For example, the first frequency-selecting surface  111  may be a sheet. 
     For example, the first frequency-selecting surface  111  may include a grid pattern  1112  comprising a repeating structure. 
     For example, the first frequency-selecting surface  111  may allow electromagnetic waves of a certain frequency to pass by means of the grid pattern  1112 . 
     For example, the outer circumferential surface of the ground conductor  1122  may be a grid pattern  1112 . 
     For example, the grid pattern  1112  may be a combination of conductor patterns in which multiple conductor patterns extending in the Y-axis direction and multiple conductor patterns extending in the circumferential direction about the Y-axis direction intersect each other, as illustrated in  FIG.  4    and  FIG.  5   . 
     For example, the first frequency-selecting surface  111  may be composed of a mesh structure in which unit cells composed of the ground conductor  1122  and apertures provided in the ground conductor  1122  are arranged periodically. 
     For example, the portions indicated by the halftone dots illustrated in  FIG.  5    indicate the grid pattern  1112 . 
     For example, the apertures may be rectangular, circular, triangular, or another shape. 
     For example, the ground conductor  1122  and the apertures may form a resonant structure. 
     For example, in the first frequency-selecting surface  111 , the properties of the resonant structure may be adjusted by changing the size of the apertures or the size of the unit cells. By adjusting the properties of the resonant structure, the frequency band of the electromagnetic waves passed by the first frequency-selecting surface  111  may be changed. 
     For example, in the grid pattern  1112 , multiple conductor patterns extending in the Y-axis direction and multiple conductor patterns extending in the circumferential direction about the Y-axis direction may be combined with each other so as to form an equivalence circuit having a capacitance component C and an inductance component L as illustrated in  FIG.  6   . 
     For example, multiple conductor patterns extending in the Y-axis direction and multiple conductor patterns extending in a direction orthogonal to the Y-axis direction on the outer circumference may be combined. 
     For example, as in the first transmission line  11  illustrated in  FIG.  4   , if the first frequency-selecting surface  111  is a grid pattern  1112 , then a second frequency-selecting surface  114  may be provided on the core wire  1123 . 
     For example, the second frequency-selecting surface  114  may allow electromagnetic waves of a certain frequency to pass. 
     For example, the second frequency-selecting surface  114  may allow electromagnetic waves, to pass, of the same frequency as the electromagnetic waves passed by the first frequency-selecting surface  111 . 
     For example, the second frequency-selecting surface  114  may be a surface, similar to the first frequency-selecting surface  111 , mainly comprising a repeating structure of a metallic pattern, and may have a surface structure that allows electromagnetic waves of a certain frequency to pass. 
     For example, the second frequency-selecting surface  114  may include a grid pattern  1142  similar to the grid pattern  1112 . 
     For example, the frequency of the electromagnetic waves transmitted on the first transmission line  11  and the frequency of the electromagnetic waves passed by the second frequency-selecting surface  114  may be different. 
       FIG.  7    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, three-dimensional patterns  1111  may be provided on both sides in a radial direction of the ground conductor  1122 . 
     For example, in  FIG.  7   , the three-dimensional patterns  1111  are provided on both sides in a radial direction (for example, the X-axis direction) of the ground conductor  1122 . 
     The first transmission line  11  is made transparent with respect to electromagnetic waves of a certain frequency by having the first frequency-selecting surface  111 . In other words, electromagnetic waves of a certain frequency pass through the first transmission line  11 . For this reason, the first transmission line  11  can suppress the adverse influence that may have on electromagnetic waves of a certain frequency. 
     Therefore, according to the embodiment in the present disclosure as above, even in cases in which, for example, the transmission line is provided in a space through which electromagnetic waves travel, the transmission line does not tend to affect the characteristics of the electromagnetic waves. 
     According to an embodiment in the present disclosure, the transmission line has a first frequency-selecting surface that allows electromagnetic waves of a first frequency to pass. 
     For example, the electromagnetic waves of the first frequency are electromagnetic waves in the direction of extension of the transmission line. 
     For example, on the transmission line, the first frequency-selecting surface that allows electromagnetic waves of the first frequency to pass covers the outer circumference of the conductor. The second frequency-selecting surface that allows electromagnetic waves of the second frequency to pass is provided on the core wire located inside the conductor. The second frequency may be a frequency in the same frequency band as the first frequency, or may be a frequency in a different frequency band from the first frequency. 
     In the first transmission line  11  illustrated in  FIG.  2   , a frequency-selecting surface is formed on the exterior of the ground conductor  1122 , thereby electromagnetically covering the interior side (the side with the core wire  1123 ) of the ground conductor  1122 . For this reason, in the first transmission line  11  illustrated in  FIG.  2   , electromagnetic waves from the outside pass through the transmission line  11  without penetrating into the interior side of the ground conductor  1122 . 
     In the first transmission line  11  illustrated in  FIG.  4   , the ground conductor  1122  itself is transparent, and electromagnetic waves from the outside sometimes penetrate into the interior side of the ground conductor  1122  (the electromagnetic waves pass through the exterior into the interior of the ground conductor  1122 ). 
     For this reason, in the first transmission line  11  illustrated in  FIG.  4   , for example, the entire first transmission line  11  can be made transparent by also providing a second frequency-selecting surface  114  on the core wire  1123 . In other words, the electromagnetic waves from the outside pass through the first transmission line  11 . 
     Although  FIG.  2    illustrates a three-dimensional pattern  1111  in which two L-shaped metallic plates are combined, the three-dimensional pattern  1111  may be any combination of patterns as long as an LC circuit can be formed. 
     For example, the three-dimensional pattern  1111  may have any shape and arrangement, and any number of metallic plates may be combined. 
     For example, the three-dimensional pattern  1111  is not limited to being a combination of metallic plates, and may be a combination of conductor blocks, a combination of conductor wires, a combination of conductor foil, a combination of conductor patterns on a substrate or the like. 
     For example, the three-dimensional pattern  1111  may be a combination including at least any of metallic plates, conductor blocks, conductor wires, conductor foil and conductor patterns on a substrate. 
     For example, an antenna according to the present disclosure may be provided with a transmission line and a reflective plate. 
       FIG.  8    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, the antenna  1  may be provided with a first transmission line  11  and a reflective plate  12 . 
     For example, the antenna  1  may be provided with a first antenna element  13 . 
     For example, the antenna  1  may be provided, on one end and the other end in the Y-axis direction of the first transmission line  11 , with a first antenna element  13  on one end and a reflective plate  12  on the other end. 
     For example, the reflective plate  12  may reflect electromagnetic waves. 
     For example, a plate of the reflective plate  12  may extend on a ZX plane. 
     For example, the plate surface of the reflective plate  12  may be a conductor. 
     For example, the electromagnetic waves transmitted on the first transmission line  11  may penetrate through the reflective plate  12 . 
     For example, the first antenna element  13  may transmit electromagnetic waves supplied to the first transmission line  11  into the surrounding space. 
     For example, the first antenna element  13  may receive electromagnetic waves from the surrounding space. When doing so, the received electromagnetic waves may be transmitted on the first transmission line  11 . 
     For example, the first antenna element  13  may be a split-ring antenna. 
     By providing the reflective plate  12 , among the waves that are polarized in various directions in the electromagnetic waves, at least the waves polarized in the direction parallel to the plate surface of the reflective plate  12  are suppressed. For this reason, the electromagnetic waves directed towards the first transmission line  11  become polarized waves mainly having a direction (for example, the Y-axis direction) intersecting the plate surface of the reflective plate  12  as the polarization direction P. 
     Therefore, according to the embodiment in the present disclosure as above, for example, the transmission line need only be made transparent in a direction intersecting the plate surface of the reflective plate. Thus, the transmission line can easily be made transparent. 
     For example, with the three-dimensional pattern  1111  illustrated in  FIG.  8   , electromagnetic waves having P as the polarization direction easily pass through. For this reason, electromagnetic waves having P as the polarization direction (advancing in a direction substantially parallel to the plate surface of the reflective plate  12 ) are easily passed to the opposite side of the transmission line, and the transmission line can easily be made transparent. 
     For example, in the transmission line according to an embodiment in the present disclosure, a first frequency-selecting surface may cover the outer circumference of a conductor. 
       FIG.  9    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, in the first transmission line  11 , the first frequency-selecting surface  111  may cover the outer circumference of the conductor  112 . 
     For example, the first frequency-selecting surface  111  may cover the outer circumference of the ground conductor  1122  over the entire circumference about the Y-axis direction. 
     For example, the first frequency-selecting surface  111  may be a sheet that covers the outer circumference of the ground conductor  1122  over the entire circumference about the Y-axis direction. 
     For example, the central axis of the first frequency-selecting surface  111  extending in the Y-axis direction and the central axis of the ground conductor  1122  extending in the Y-axis direction may be coaxial. 
     For example, the central axis of the first frequency-selecting surface  111  extending in the Y-axis direction, the central axis of the ground conductor  1122  extending in the Y-axis direction and the central axis of the core wire  1123  extending in the Y-axis direction may be coaxial. 
     For example, the inner circumference of the first frequency-selecting surface  111  and the outer circumference of the ground conductor  1122  may be electrically isolated by space, a dielectric or the like. 
     For example, a space between the inner circumference of the first frequency-selecting surface  111  and the outer circumference of the ground conductor  1122  may be entirely or at least partially filled with a dielectric so as to extend in the Y-axis direction. 
     By covering the outer circumference of the conductor  112  with the first frequency-selecting surface  111 , the first transmission line  11  can be made transparent without being affected by the structure of the conductor  112 . Thus, electromagnetic waves from the outside pass through the first transmission line  11 , regardless of the shape of the conductor  112 . 
     Therefore, according to the embodiment in the present disclosure as above, for example, the transmission line can suppress the adverse influence that may have on electromagnetic waves of a certain frequency, without being affected by the structure of the conductor. 
       FIG.  9    illustrates a reflective plate  12 . However, a reflective plate  12  need not be provided as long as the first transmission line  11  can be made transparent. 
       FIG.  9    illustrates a first antenna element  13 . However, a first antenna element  13  need not be provided. 
       FIG.  9    illustrates the first transmission line  11  applied to a transmission line in an antenna  1 . However, the first transmission line  11  may be applied to a transmission line other than that in an antenna. 
     For example, in the transmission line according to an embodiment in the present disclosure, a first frequency-selecting surface may be provided on a ground conductor. 
       FIG.  10    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, in the first transmission line  11 , the first frequency-selecting surface  111  may be provided on the ground conductor  1122 . 
     For example, the ground conductor  1122  may cover the outer circumference of the core wire  1123  over the entire circumference about the Y-axis direction. 
     For example, the central axis of the ground conductor  1122  extending in the Y-axis direction and the central axis of the core wire  1123  extending in the Y-axis direction may be coaxial. 
     For example, the inner circumference of the ground conductor  1122  and the outer circumference of the core wire  1123  may be electrically isolated by space, a dielectric or the like. 
     For example, a space between the inner circumference of the ground conductor  1122  and the outer circumference of the core wire  1123  may be entirely or at least partially filled with a dielectric so as to extend in the Y-axis direction. 
     For example, the first transmission line  11  may be a coaxial cable having the ground conductor  1122  as an outer conductor and the core wire  1123  as an inner conductor. 
     For example, the core wire  1123  may penetrate through the reflective plate  12  so that the electromagnetic waves transmitted on the first transmission line  11  penetrate through the reflective plate  12 . 
     For example, the core wire  1123  and the ground conductor  1122  may each be connected to the first antenna element  13  at locations that are away from each other. 
     For example, if the first antenna element  13  is a split-ring antenna, the core wire  1123  may be connected to the first antenna element  13  near the split, and the ground conductor  1122  may be connected to the first antenna element  13  at a location away from the split. 
       FIG.  11    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, the ground conductor  1122  may be a pair of opposing planar patterns  11221  that sandwich the core wire  1123  in the Z-axis direction. 
     For example, each planar pattern  11221  may extend in the Y-axis direction. 
     For example, each planar pattern  11221  may have a plate surface that extends on the XY plane. 
     For example, the conductor  112  may be provided with multiple via-holes  11222 . 
     For example, the pair of planar patterns  11221  may be connected to each other through the multiple via-holes  11222 . 
     For example, the pair of planar patterns  11221  may be connected to each other through the multiple via-holes  11222  at both ends in the X-axis direction. 
     For example, the pair of planar patterns  11221  and the multiple via-holes  11222  may cover the core wire  1123  with respect to electromagnetic waves of a certain frequency that are passed by the first frequency-selecting surface  111 . 
     For example, the central axis of the space sandwiched by the pair of planar patterns  11221  extending in the Y-axis direction and the central axis of the core wire  1123  extending in the Y-axis direction may be coaxial. 
     For example, the ground conductor  1122  may be provided with a lead wire  11223  or the like so as to be electrically connected to the first antenna element  13 . 
     By providing the first frequency-selecting surface  111  on the ground conductor  1122 , the first transmission line  11  is made transparent for electromagnetic waves of a certain frequency. In other words, electromagnetic waves of a certain frequency pass through the first transmission line  11 . For this reason, the first transmission line  11  can suppress the adverse influence that may have on electromagnetic waves of a certain frequency. 
     Therefore, according to the embodiment in the present disclosure as above, even if the transmission line is provided in a space through which electromagnetic waves travel, the transmission line does not tend to affect the characteristics of the electromagnetic waves. 
     Furthermore, for example, by covering the core wire  1123  with respect to electromagnetic waves of a certain frequency by means of the ground conductor  1122  provided with the first frequency-selecting surface  111 , the ground conductor  1122  can be made transparent with respect to electromagnetic waves of a certain frequency, and not only the ground conductor  1122  itself, but at the same time, the core wire  1123  covered by the ground conductor  1122  may also be made transparent 
       FIG.  10    and  FIG.  11    both illustrate a reflective plate  12 . However, a reflective plate  12  need not be provided as long as the first transmission line  11  can be made transparent. 
       FIG.  10    and  FIG.  11    both illustrate a first antenna element  13 . However, a first antenna element  13  need not be provided. 
       FIG.  10    and  FIG.  11    both illustrate the first transmission line  11  applied to a transmission line in an antenna  1 . However, the first transmission line  11  may be applied to a transmission line other than that in an antenna. 
       FIG.  11    illustrates multiple via-holes  11222 . However, multiple via-holes  11222  need not be provided as long as the core wire  1123  is covered by the first frequency-selecting surface  111 . 
       FIG.  11    illustrates a first antenna element  13 , a core wire  1123  and a pair of planar patterns  11221 . However, the first antenna element  13 , the core wire  1123  and the pair of planar patterns  11221  may be formed by a single substrate. 
       FIG.  11    illustrates the core wire  1123  and the pair of opposing planar patterns  11221  that sandwich the core wire  1123  in the Z-axis direction. However, the core wire  1123  and the planar patterns  11221  may be in any form such as a microstrip line, a strip line, a three-dimensional circuit or a coplanar line. 
     For example, in a transmission line according to an embodiment in the present disclosure, a first frequency-selecting surface may be provided on the ground conductor and a second frequency-selecting surface may be provided on the core wire. 
       FIG.  12    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, in the first transmission line  11 , the first frequency-selecting surface  111  may be provided on the ground conductor  1122 , and the second frequency-selecting surface  114  may be provided on the core wire  1123 . 
     For example, the second frequency-selecting surface  114  may allow electromagnetic waves of a certain frequency to pass. 
     For example, the second frequency-selecting surface  114  may allow electromagnetic waves, to pass, of the same frequency as the electromagnetic waves passed by the first frequency-selecting surface  111 . For example, the second frequency-selecting surface  114  may allow electromagnetic waves, to pass, of a frequency in the same frequency band as the electromagnetic waves passed by the first frequency-selecting surface  111 . 
     For example, the second frequency-selecting surface  114  may include a three-dimensional pattern  1141 . 
     For example, the second frequency-selecting surface  114  may allow electromagnetic waves of a certain frequency to pass by the combination of the surface of the core wire  1123  and the three-dimensional pattern  1141 . 
     For example, the three-dimensional pattern  1141  may be provided on both sides in a radial direction of the core wire  1123 . In other words, the three-dimensional pattern  1141  may be provided on both sides in the direction of a diameter of the core wire  1123  orthogonal to the Y-axis direction of the core wire  1123 . 
     For example, the second frequency-selecting surface  114  may include a grid pattern as illustrated in  FIG.  4   ,  FIG.  5    or  FIG.  6   . 
     For example, the second frequency-selecting surface  114  may allow electromagnetic waves of a certain frequency to pass by means of the grid pattern. 
     For example, the surface of the core wire  1123  may be a grid pattern. 
     For example, a pair of planar patterns  11221  ( FIG.  11   ) may cover or may not cover the core wire  1123  with respect to electromagnetic waves of a certain frequency that are passed by the first frequency-selecting surface  111 . 
     The first transmission line  11  is made transparent with respect to electromagnetic waves of a certain frequency by having a first frequency-selecting surface  111  and a second frequency-selecting surface  114 . In particular, the ground conductor  1122  is made transparent by the first frequency-selecting surface  111 , and the core wire  1123  is made transparent by the second frequency-selecting surface  114 . For this reason, for electromagnetic waves of the certain frequency, even if the core wire  1123  is not covered by the ground conductor  1122 , the first transmission line  11  is made transparent. In other words, electromagnetic waves of the certain frequency pass through the first transmission line  11 . 
     Therefore, according to the embodiment in the present disclosure as above, the transmission line will not tend to affect the characteristics of electromagnetic waves, even when the transmission line is provided in a space through which electromagnetic waves travel, regardless of, for example, the relationship between the ground conductor and the core wire, such as the arrangement and the structures thereof. 
       FIG.  12    illustrates a reflective plate  12 . However, a reflective plate  12  need not be provided as long as the first transmission line  11  can be made transparent. 
       FIG.  12    illustrates a first antenna element  13 . However, a first antenna element  13  need not be provided. 
       FIG.  12    illustrates the first transmission line  11  applied to a transmission line in an antenna  1 . However, the first transmission line  11  may be applied to a transmission line other than that in an antenna. 
     For example, the transmission line according to an embodiment in the present disclosure may be a power supply line for a first antenna element in a multiantenna. 
       FIG.  13    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  14    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  15    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  16    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, the first transmission line  11  may be a power supply line for a first antenna element  13  in a multiantenna. 
     For example, the antenna  1  may be provided with a first transmission line  11 , a first antenna element  13 , a second transmission line  14 , and a second antenna element  15 . 
     For example, the electromagnetic waves transmitted on the first transmission line  11  and the electromagnetic waves transmitted on the second transmission line  14  may both penetrate through the reflective plate  12 . 
     For example, the electromagnetic waves supplied to the first transmission line  11  may be radiated from the first antenna element  13  and the electromagnetic waves supplied to the second transmission line  14  may be radiated from the second antenna element  15 . 
     For example, the first transmission line  11  may be able to supply electromagnetic waves to the first antenna element  13  while also being made transparent with respect to electromagnetic waves of a certain frequency in the multiantenna. In other words, electromagnetic waves of the certain frequency in the multiantenna may pass through the first transmission line  11 . 
     The first transmission line  11  may be able to supply electromagnetic waves to the first antenna element  13  while also being made transparent with respect to electromagnetic waves of a certain frequency in the multiantenna. 
     For this reason, the first transmission line  11  can suppress the adverse influence that may have on electromagnetic waves of a certain frequency. 
     Therefore, according to the embodiment in the present disclosure as above, for example, the transmission line will not tend to affect the characteristics of electromagnetic waves of a certain frequency in a multiantenna. 
       FIG.  13   ,  FIG.  14   ,  FIG.  15    and  FIG.  16    illustrate reflective plates  12 . However, a reflective plate  12  need not be provided as long as the first transmission line  11  can be made transparent. 
     The second transmission lines  14  illustrated in  FIG.  13   ,  FIG.  14   ,  FIG.  15    and  FIG.  16    do not have frequency-selecting surfaces. However, they may have frequency-selecting surfaces. 
     The second transmission lines  14  illustrated in  FIG.  13   ,  FIG.  14   ,  FIG.  15    and  FIG.  16    may allow electromagnetic waves of a certain frequency to pass. 
     For example, in an embodiment in the present disclosure, the transmission line may be a power supply line for a first antenna element in a multiantenna, wherein the multiantenna supports electromagnetic waves of a first frequency and electromagnetic waves of a second frequency, and the transmission line allows electromagnetic waves of the first frequency to pass and supplies electromagnetic waves of the second frequency to the first antenna element. 
       FIG.  17    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  18    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  19    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  20    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, the first transmission line  11  may be a power supply line for a first antenna element  13  in a multiantenna that supports electromagnetic waves of a first frequency f 1  and electromagnetic waves of a second frequency f 2 . 
     For example, the first transmission line  11  may allow electromagnetic waves of the first frequency f 1  to pass and may supply electromagnetic waves of the second frequency f 2  to the first antenna element  13 . 
     For example, the electromagnetic waves of the second frequency f 2  are electromagnetic waves of a frequency in a different frequency band from the electromagnetic waves of the first frequency f 1 . 
     For example, the first antenna element  13  may radiate electromagnetic waves of the second frequency f 2 . 
     For example, the second transmission line  14  may supply electromagnetic waves of the first frequency f 1  to the second antenna element  15 . 
     For example, the second antenna element  15  may radiate electromagnetic waves of the first frequency f 1 . 
     The first transmission line  11  may be able to supply electromagnetic waves of the second frequency f 2  to the first antenna element  13  while also being made transparent with respect to electromagnetic waves of the first frequency f 1  in the multiantenna. For this reason, the first transmission line  11  can suppress the adverse influence that may have on electromagnetic waves of the first frequency f 1  supported by the multiantenna. 
     Thus, according to each of the embodiments in  FIG.  17    to  FIG.  20   , the first transmission line  11  can supply electromagnetic waves of the second frequency f 2  to the first antenna element  13 , and is made transparent with respect to electromagnetic waves of the first frequency f 1  in the multiantenna. 
     Therefore, according to the embodiment in the present disclosure as above, for example, the transmission line can supply electromagnetic waves of the second frequency that are radiated while also not tending to affect the characteristics of the electromagnetic waves of the first frequency supported by the multiantenna. 
       FIG.  21    is an example of the radiation pattern of the second antenna element  15  according to an embodiment in the present disclosure. 
     For example, the solid lines indicate the radiation pattern of electromagnetic waves of the first frequency f 1  in the second antenna element  15  in the antenna  1  illustrated in  FIG.  17   . In other words, the solid lines indicate the radiation pattern of the electromagnetic waves of the first frequency in the second antenna element when there is a first frequency-selecting surface on the first transmission line. 
     For example, the dashed lines indicate the radiation pattern of electromagnetic waves of the first frequency f 1  in the second antenna element  15  when the first transmission line  11  is not provided in the antenna  1  illustrated in  FIG.  17   . In other words, the dashed lines indicate the radiation pattern of the electromagnetic waves of the first frequency f 1  in the second antenna element  15  when only the second antenna element  15  is provided. 
     For example, the single-dotted chain lines indicate the radiation pattern of electromagnetic waves of the first frequency f 1  in the second antenna element  15  when the first frequency-selecting surface  111  is not provided on the first transmission line  11  in the antenna  1  illustrated in  FIG.  17   . In other words, the single-dotted chain lines indicate the radiation pattern of the electromagnetic waves of the first frequency f 1  in the second antenna element  15  when a frequency-selecting surface  111  is not provided on the first transmission line  11 . 
     As can be understood from the comparison results indicated in  FIG.  21   , the radiation pattern of the single-dotted chain lines is significantly changed in comparison to the radiation pattern of the dashed lines, whereas the radiation pattern of the solid lines is almost unchanged in comparison to the radiation pattern of the dashed lines. In this way, the first transmission line suppresses the adverse influence that may have on electromagnetic waves of the first frequency supported by the multiantenna. 
       FIG.  17   ,  FIG.  18   ,  FIG.  19    and  FIG.  20    illustrate reflective plates  12 . However, a reflective plate  12  need not be provided as long as the first transmission line  11  can be made transparent. 
     The second transmission lines  14  illustrated in  FIG.  17   ,  FIG.  18   ,  FIG.  19    and  FIG.  20    do not have frequency-selecting surfaces. However, they may have frequency-selecting surfaces. 
     For example, the second transmission lines  14  illustrated in  FIG.  17   ,  FIG.  18   ,  FIG.  19    and  FIG.  20    may allow electromagnetic waves of the second frequency f 2  to pass. 
     In this case, the second transmission line  14  can supply electromagnetic waves of the first frequency f 1  to the second antenna element  15  while also being made transparent with respect to electromagnetic waves of the second frequency f 2  in the multiantenna. 
     For example, in an embodiment in the present disclosure, the transmission line is a power supply line for a first antenna element in a multiantenna, wherein the multiantenna supports electromagnetic waves of a first frequency and electromagnetic waves of a second frequency. The transmission line may allow electromagnetic waves of the first frequency to pass, supply electromagnetic waves of the second frequency to the first antenna element, and allows electromagnetic waves of the second frequency to pass. 
       FIG.  22    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  23    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  24    is an example of an equivalent circuit of a transmission line according to an embodiment in the present disclosure. 
       FIG.  25    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
       FIG.  26    is a perspective view of an example of a transmission line according to an embodiment in the present disclosure. 
     For example, the first transmission line  11  may be a power supply line for a first antenna element  13  in a multiantenna that supports electromagnetic waves of the first frequency f 1  and electromagnetic waves of the second frequency f 2 . 
     For example, the first transmission line  11  may allow electromagnetic waves of the first frequency f 1  to pass, supply electromagnetic waves of the second frequency f 2  to the first antenna element  13 , and allow electromagnetic waves of the second frequency f 2  to pass. 
     For example, electromagnetic waves of the second frequency f 2  are electromagnetic waves of a frequency in a different frequency band from the electromagnetic waves of the first frequency f 1 . 
     For example, the first antenna element  13  may radiate electromagnetic waves of the second frequency f 2 . 
     For example, the second transmission line  14  may supply electromagnetic waves of the first frequency f 1  to the second antenna element  15 . 
     For example, the second antenna element  15  may radiate electromagnetic waves of the first frequency f 1 . 
     For example, the first frequency-selecting surface  111  may be configured so that the first transmission line  11  allows electromagnetic waves of the first frequency f 1  and electromagnetic waves of the second frequency f 2  to pass. 
     For example, the first frequency-selecting surface  111  may include a three-dimensional pattern  1111  and an auxiliary pattern  1114 . 
     For example, the first frequency-selecting surface  111  may allow electromagnetic waves of the first frequency f 1  and electromagnetic waves of the second frequency f 2  to pass by a combination of the surface of the ground conductor  1122 , the three-dimensional pattern  1111 , and the auxiliary pattern  1114 . 
     For example, as illustrated in  FIG.  22   , of both sides in a radial direction of the first transmission line  11 , the three-dimensional pattern  1111  may be provided on one side and the auxiliary pattern  1114  of an L-shape metallic plate may be provided on the other side. 
     For example, of both sides in a radial direction of the first transmission line  11 , the three-dimensional pattern  1111  may be provided on one end and the auxiliary pattern  1114  may be provided on the other end. 
     For example, as illustrated in  FIG.  23   , the three-dimensional pattern  1111  may be provided on a surface of the first transmission line  11 , and the auxiliary pattern  1114  may be provided in a space formed between the surface of the first transmission line  11  and the three-dimensional pattern  1111 . 
     For example, the three-dimensional pattern  1111  may be provided on a surface of the first transmission line  11  and the auxiliary pattern  1114  may be provided in a space formed between the surface of the first transmission line  11  and the three-dimensional pattern  1111  so as to form the LC circuit illustrated in  FIG.  24   . 
     For example, the respective metallic plates in the three-dimensional pattern  1111  may be provided so that the plate surfaces of L-shaped metallic plates in the three-dimensional pattern  1111  extend along the XY plane. 
     For example, the respective metallic plates in the auxiliary pattern  1114  may be provided so that the plate surfaces of the metallic plates in the auxiliary pattern  1114  extend along the XY plane. 
     For example, the auxiliary pattern  1114  may be a combination of an L-shaped metallic plate and an I-shaped metallic plate. 
     The first transmission line  11  can supply electromagnetic waves of the second frequency f 2  to the first antenna element  13 , and is made transparent with respect to electromagnetic waves of the first frequency f 1  in the multiantenna, and with respect to electromagnetic waves of the second frequency f 2  in the multiantenna. 
     For this reason, the first transmission line  11  can suppress the adverse influence that may have on electromagnetic waves of the first frequency f 1  and the second frequency f 2  supported by the multiantenna. 
     If a frequency-selecting surface is provided in order to make the transmission line transparent with respect to electromagnetic waves of the first frequency f 1 , the frequency-selecting surface sometimes adversely affects electromagnetic waves of the second frequency f 2  radiated through the transmission of the transmission line itself. 
     In contrast therewith, the first transmission line  11  according to an embodiment in the present disclosure is made transparent with respect to electromagnetic waves of the first frequency f 1  and the second frequency f 2 . For this reason, it is possible to suppress the adverse influence that may have on electromagnetic waves of the second frequency f 2  radiated through the transmission of the first transmission line  11  itself. 
     Therefore, according to the embodiment in the present disclosure as above, for example, even when the transmission line is provided in a space through which electromagnetic waves travel, the transmission line does not tend to affect the characteristics of electromagnetic waves of the first frequency and the second frequency. 
       FIG.  22   ,  FIG.  25    and  FIG.  26    illustrate reflective plates  12 . However, a reflective plate  12  need not be provided as long as the first transmission line  11  can be made transparent. 
     The second transmission lines  14  illustrated in  FIG.  22   ,  FIG.  25    and  FIG.  26    do not have frequency-selecting surfaces. However, they may have the frequency-selecting surfaces. 
     The second transmission lines  14  illustrated in  FIG.  22   ,  FIG.  25    and  FIG.  26    do not have frequency-selecting surfaces. However, they may be configured so as to have the frequency-selecting surfaces and may allow electromagnetic waves of the second frequency f 2  to pass. 
     The second transmission lines  14  illustrated in  FIG.  22   ,  FIG.  25    and  FIG.  26    do not have frequency-selecting surfaces. However, they may be configured so as to have the frequency-selecting surfaces and may allow electromagnetic waves of the first frequency f 1  and the second frequency f 2  to pass. 
     The three-dimensional patterns  1111  illustrated in  FIG.  22   ,  FIG.  23   ,  FIG.  25    and  FIG.  26    are provided on one side in a radial direction of the ground conductors  1122 . However, they may be provided on both sides in the radial direction of the ground conductors  1122 . 
     The auxiliary patterns  1114  illustrated in  FIG.  22   ,  FIG.  23   ,  FIG.  25    and  FIG.  26    are provided on one side in a radial direction of the ground conductors  1122 . However, they may be provided on both sides in the radial direction of the ground conductors  1122 .  FIG.  22   ,  FIG.  23   ,  FIG.  25    and  FIG.  26    illustrate first frequency-selecting surfaces  111  including three-dimensional patterns  1111  and auxiliary patterns  1114 . However, they may have any configuration as long as the first transmission lines  11  can be made transparent with respect to electromagnetic waves of the first frequency f 1  and the second frequency f 2 . 
     For example, the first frequency-selecting surfaces  111  may include grid patterns comprising repeating structures so that electromagnetic waves of the first frequency f 1  and the second frequency f 2  are passed. 
     INDUSTRIAL APPLICABILITY 
     According to an embodiment in the present disclosure, for example, even when a transmission line is provided in a space through which electromagnetic waves travel, the characteristics of the electromagnetic waves are not easily affected. 
     REFERENCE SIGNS LIST 
     
         
           1  Antenna 
           11  First transmission line (transmission line) 
           111  First frequency-selecting surface 
           1111  Three-dimensional pattern 
           1112  Grid pattern 
           1114  Auxiliary pattern 
           112  Conductor 
           1122  Ground conductor 
           11221  Planar pattern 
           11222  Via-hole 
           11223  Lead wire 
           1123  Core wire 
           114  Second frequency-selecting surface 
           1141  Three-dimensional pattern 
           1142  Lattice pattern 
           12  Reflective plate 
           13  First antenna element 
           14  Second transmission line 
           15  Second antenna element 
         C Capacitance component 
         L Inductance component 
         P Polarization direction