Antennas and Communication Systems

Abstract

To provide an antenna that obtains large radiation power, achieves desired directivity, and uses a coaxial cable, and a communication system that includes the antenna.SOLUTION: An antenna 10 includes an inner conductor 21, outer conductors 220, 221, and 222, and a plurality of slits 241, 242, and 243. The outer conductors are arranged along the extension direction of the inner conductor and are spaced apart from the inner conductor in the circumferential direction of the inner conductor. A plurality of first slits is formed independently of each other at positions that are spaced apart from each other in the extension direction of the outer conductors.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an antenna using a coaxial cable and a communication system including this antenna. [Background technology]

[0002] Conventionally, various antennas using coaxial cables have been devised.

[0003] For example, Patent Document 1 describes a leaky coaxial cable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-239160 Summary of the Invention [Problem to be solved by the invention]

[0005] However, leaky coaxial cables have a low radiated power and it is difficult to achieve a desired directivity.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an antenna that can obtain large radiated power and achieve a desired directivity. [Means for solving the problem]

[0007] The antenna of the present invention comprises an inner conductor, an outer conductor, and a plurality of first slits. The outer conductor is arranged along the direction in which the inner conductor extends and is spaced apart in the circumferential direction of the inner conductor. The plurality of first slits are formed independently of one another at positions spaced apart from one another in the direction in which the outer conductor extends.

[0008] In this configuration, a predetermined radiation power can be ensured by radiating electromagnetic waves from the plurality of first slits, and further, a desired directivity can be achieved according to the relative positions of the plurality of first slits.

[0009] The antenna of the present invention includes a first dielectric material filled into the plurality of first slits, and this configuration allows the shape of the first slits to be stably maintained.

[0010] The antenna of the present invention includes a second dielectric covering the outer periphery of the outer conductor. With this configuration, the outer conductor is protected from the outside while allowing electromagnetic waves to be radiated.

[0011] The antenna of the present invention also includes a waterproof film that covers the outer peripheral surface of the second dielectric body, thereby improving the waterproofness of the antenna.

[0012] In the antenna of the present invention, the formation intervals of the plurality of first slits are set so that the wavelength in the transmission path formed by the inner conductor and the outer conductor is λ g1 As, λ g1 and λ g1 In this configuration, a predetermined directivity can be set in the direction in which the inner conductor extends (the direction in which the electromagnetic waves are transmitted in the coaxial line portion) and in the circumferential direction.

[0013] In the antenna of the present invention, the first slits are formed at different intervals, and this configuration allows for the emission of electromagnetic waves at a plurality of frequencies.

[0014] The antenna of the present invention includes a plurality of second slits formed in the outer conductor and extending at an angle other than 0° and 90° with respect to the extending direction. With this configuration, electromagnetic waves can be radiated from the plurality of second slits as well.

[0015] In the antenna of the present invention, the length of the plurality of second slits is half the wavelength different from the wavelength of the electromagnetic wave radiated from the first slits. With this configuration, the frequency of the electromagnetic wave radiated from the plurality of second slits can be made different from the frequency of the electromagnetic wave radiated from the plurality of first slits.

[0016] The antenna of the present invention includes a third slit formed in the outer conductor and reaching both ends in the extending direction. In this configuration, the outer conductor can be realized by bending a plate-shaped member.

[0017] In the antenna of the present invention, the plurality of first slits extend at an angle other than 0° or 90° with respect to the direction in which the outer conductor extends. With this configuration, electromagnetic waves can be radiated with desired radiated power and desired directivity.

[0018] In the antenna of this invention, the multiple first slots are formed in the extension direction at intervals of wavelength × (2n + 1) / 2 (n is an integer equal to or greater than 0) in the transmission path formed by the inner conductor and outer conductor. With this configuration, it is possible to radiate electromagnetic waves with a predetermined directivity in a plane perpendicular to the axial direction of the antenna.

[0019] In the antenna of the present invention, the plurality of first slits include a plurality of third slits that form pairs and a plurality of fourth slits that form pairs. The lengths of the plurality of third slits in the long side direction are different from the lengths of the plurality of fourth slits in the long side direction. The spacing between the plurality of third slits is different from the spacing between the plurality of fourth slits. With this configuration, electromagnetic waves of a plurality of frequencies can be radiated.

[0020] In the antenna of the present invention, the fourth slits are formed at positions sandwiching the third slits in the direction of extension of the outer conductor. With this configuration, the antenna that radiates electromagnetic waves of multiple frequencies can be miniaturized.

[0021] In the antenna of the present invention, the outer conductor has a plurality of walls, each having a flat surface. The plurality of third slits and the plurality of fourth slits are formed in different walls of the plurality of walls. This configuration can achieve more diverse radiation characteristics.

[0022] The antenna of the present invention includes an antenna function unit having an inner conductor, an outer conductor, and a slit, and a coaxial connector connected to the antenna function unit. With this configuration, the antenna (antenna function unit) can be easily connected to an external coaxial cable.

[0023] In the antenna of this invention, the outer conductor of the coaxial connector has an opening through which a circumferential portion of the inner conductor is exposed to the outside. With this configuration, the inner conductor of the antenna can be easily joined to the inner conductor of the external coaxial cable using a conductive joining material such as solder.

[0024] The communication system of the present invention includes an antenna, a coaxial cable to which a coaxial connector is connected, and a communication device connected to the coaxial cable. With this configuration, by appropriately routing the coaxial cable, it is possible to realize a communication system that allows communication while arranging the antenna and communication device in desired positions.

[0025] The communication system of the present invention includes a plurality of coaxial cables and communication devices. The plurality of coaxial cables are respectively connected to coaxial connectors at both ends of an antenna, and the plurality of communication devices are respectively connected to the plurality of coaxial cables. The communication system of the present invention includes a plurality of antennas, coaxial cables, and communication devices. The plurality of antennas and the plurality of communication devices are connected in series using the plurality of coaxial cables. With these configurations, the desired positional relationship and connection relationship between the antennas and communication devices can be easily achieved.

[0026] The communication system of the present invention includes an absorbing resistor connected to the open end of the coaxial cable, and this configuration allows the open end of the coaxial cable to be terminated appropriately. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a plan sectional view showing the configuration of an antenna according to a first embodiment. [Figure 2] FIG. 2 is a side cross-sectional view showing the configuration of the antenna according to the first embodiment. [Figure 3] FIG. 3 is an external perspective view of the antenna according to the first embodiment. [Figure 4] FIG. 4 is a functional block diagram of the antenna according to the first embodiment. [Figure 5]FIG. 5 is a diagram showing an example of radiation characteristics of the antenna according to the first embodiment. [Figure 6] 6(A), 6(B), and 6(C) are diagrams showing examples of radiation characteristics. [Figure 7] FIG. 7(A) is a side cross-sectional view showing the configuration of an antenna according to the second embodiment, and FIG. 7(B) is an enlarged plan view of an antenna function section in the antenna according to the second embodiment. [Figure 8] 8(A) and 8(B) are diagrams showing the derived configuration of the outer conductor. [Figure 9] FIG. 9(A) is a plan view showing the configuration of an antenna according to the third embodiment, and FIG. 9(B) is a side cross-sectional view showing the configuration of an antenna according to the third embodiment. [Figure 10] FIG. 10 is an external perspective view of the antenna according to the third embodiment. [Figure 11] 11A and 11B are diagrams showing an example of radiation characteristics of the antenna according to the third embodiment. [Figure 12] FIG. 12(A) is a plan view showing the configuration of an antenna according to the fourth embodiment, and FIG. 12(B) is a side cross-sectional view showing the configuration of an antenna according to the fourth embodiment. [Figure 13] 13(A), 13(B), and 13(C) are diagrams showing the configuration of a communication system according to an embodiment of the present invention. [Figure 14] 14(A), 14(B), and 14(C) are diagrams showing the configuration of a communication system according to an embodiment of the present invention. [Figure 15] FIG. 15 is a configuration diagram of a communication system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] [First embodiment] An antenna according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan sectional view showing the configuration of the antenna according to the first embodiment. FIG. 2 is a side sectional view showing the configuration of the antenna according to the first embodiment. Note that the terms plan and side are given for the convenience of explanation and do not define the positioning orientation of the antenna. FIG. 3 is an external perspective view of the antenna according to the first embodiment.

[0029] 1, 2, and 3, the antenna 10 includes an inner conductor 21, an outer conductor 220, an outer conductor 221, an outer conductor 222, a dielectric 23, a slit 241, a slit 242, a slit 243, a dielectric 241DE, a dielectric 242DE, a dielectric 243DE, a dielectric 31, and a waterproof film 32. Note that the dielectric 241DE, the dielectric 242DE, the dielectric 243DE, the dielectric 31, and the waterproof film 32 may be omitted.

[0030] The inner conductor 21 is a linear conductor. The inner conductor 21 has a shape that extends in a predetermined direction (in the figure, a direction parallel to the z-axis). A cross section of the inner conductor 21 perpendicular to the direction of extension (in the figure, a cross section cut on the xy plane) is circular. In other words, the inner conductor 21 has a columnar shape that is elongated in the z-axis direction and has a cylindrical outer circumferential surface.

[0031] The outer conductor 220 is a cylindrical conductor that is long in the z-axis direction. The axial direction of the outer conductor 220 and the axial direction of the inner conductor 21 are the same (parallel). The inner conductor 21 is disposed inside the cylindrical outer conductor 220. In other words, the outer conductor 220 is disposed along the extension direction of the inner conductor 21 and is tubular and disposed at a distance from the outer peripheral surface of the inner conductor 211.

[0032] The dielectric 23 is disposed between the inner conductor 21 and the outer conductor 220 .

[0033] As a result, a coaxial line is formed by the inner conductor 21, the outer conductor 220, and the dielectric 23.

[0034] Both ends of the inner conductor 21 in the extending direction protrude beyond the outer conductor 200 .

[0035] One end of the inner conductor 21 that protrudes beyond the outer conductor 220 is covered with the outer conductor 221. The outer conductor 221 has a substantially cylindrical main body. This allows the inner conductor 21 and the outer conductor 221 to form a coaxial line.

[0036] The outer conductor 221 also has an opening 2210 that exposes a portion of the outer circumferential surface of the inner conductor 21 to the outside. The opening 2210 is formed at a position where the first end 21E1 of the inner conductor 21 is exposed.

[0037] With this configuration, the portion consisting of the inner conductor 21 and the outer conductor 221 serves as a coaxial connector on one end of the antenna 10 .

[0038] The outer conductor 221 also has a flange that protrudes outward from the main body. The flange of the outer conductor 221 is located on the side closer to the outer conductor 220. This flange, together with the flange of the outer conductor 222, is used to fix the dielectric 31 and the waterproof film 32, which will be described later.

[0039] The other end of the inner conductor 21 that protrudes beyond the outer conductor 220 is covered with the outer conductor 222. The outer conductor 222 has a substantially cylindrical main body. This allows the inner conductor 21 and the outer conductor 222 to form a coaxial line.

[0040] The outer conductor 222 also has an opening 2220 that exposes a portion of the outer circumferential surface of the inner conductor 21 to the outside. The opening 2220 is formed at a position where the second end 21E2 of the inner conductor 21 is exposed.

[0041] With this configuration, the portion consisting of the inner conductor 21 and the outer conductor 222 serves as the coaxial connector on the other end side of the antenna 10 .

[0042] The outer conductor 222 also has a flange that protrudes outward from the main body. The flange of the outer conductor 222 is located on the side closer to the outer conductor 220. This flange, together with the flange of the outer conductor 221, is used to secure the dielectric 31 and the waterproof film 32, which will be described later.

[0043] In this configuration, the antenna 10 has a slit 242 at a predetermined position in the extending direction of the outer conductor 220. The antenna 10 also has a slit 241 between the outer conductors 220 and 221, and a slit 243 between the outer conductors 220 and 222.

[0044] The slits 242 divide the outer conductor 220 into a plurality of conductor portions in the extension direction, and are grooves in which no conductor is formed over the entire circumference of the outer conductor 220. The slits 241 separate one end of the outer conductor 220 from the outer conductor 221, and the slits 243 separate the other end of the outer conductor 220 from the outer conductor 222, and are grooves in which no conductor is formed over the entire circumference of the outer conductor 220.

[0045] At such slits 241, 242, and 243, a portion of the electromagnetic waves transmitted through the coaxial line is radiated to the outside. As a result, the antenna 10 functionally realizes the configuration shown in FIG. 4. FIG. 4 is a diagram showing the antenna according to the first embodiment in functional blocks. As shown in FIG. 4, the antenna 10 has a configuration in which a connection part (transmission line) PT1, an antenna ANT1, a transmission line TL12, an antenna ANT2, a transmission line TL23, an antenna ANT3, and a connection part (transmission line) PT2 are connected from one end to the other end. The portion consisting of the antenna ANT1, the transmission line TL12, the antenna ANT2, the transmission line TL23, and the antenna ANT3 constitutes the antenna functional part of the antenna 10.

[0046] The connection part (transmission line) PT1 is realized by a coaxial connector including an outer conductor 221. The antenna ANT1 is realized by a slit 241. The transmission line TL12 is realized by a coaxial line between the slit 241 and the slit 242. The antenna ANT2 is realized by a slit 242. The transmission line TL23 is realized by a coaxial line between the slit 242 and the slit 243. The antenna ANT3 is realized by a slit 243. The connection part (transmission line) PT2 is realized by a coaxial connector including the outer conductor 222.

[0047] The electromagnetic waves radiated from the multiple antennas ANT1, ANT2, and ANT3 act constructively in a predetermined direction depending on the shape and positional relationship of the multiple slits 241, 242, and 243, which will be described later. This allows the antenna 10 to have a predetermined directivity and achieve a predetermined level of radiated power.

[0048] (More specific configuration for realizing the radiation characteristics of the antenna 10) More specifically, the plurality of slits 241, 242, and 243 have the following shapes and positional relationships.

[0049] Slit 241 is formed with width G241, slit 242 is formed with width G242, and slit 243 is formed with width G243. Widths G241, G242, and G243 are determined by the radiated power of antenna 10, that is, the impedance of antenna 10, and the degree of coupling to the coaxial line that constitutes antenna 10. In this example, widths G241, G242, and G243 are set to be the same, but may be different.

[0050] The distance L12 between the slits 241 and 242 and the distance L23 between the slits 242 and 243 are determined by the frequency and directivity of the electromagnetic waves radiated by the antenna 10. As an example, the distance L12 and the distance L23 are the same and are set as follows: If the wavelength of the electromagnetic waves radiated by the antenna 10 within the coaxial line is λ g1 The distance L12 and the distance L13 are λ g1 and λ g1 That is, the plurality of slits 241, 242, and 243 are formed at distances such that the phases of the electromagnetic waves radiated therefrom are neither in phase nor out of phase.

[0051] This allows the antenna 10 to achieve directivity that is different from directivity with substantially the same strength in all azimuth directions perpendicular to the axial direction of the coaxial line (circumferential omnidirectionality) and directivity that is substantially null in all azimuth directions. In other words, the antenna 10 can achieve directivity that cannot be achieved with existing collinear antennas.

[0052] For example, by appropriately setting the distances L12 and L13, the antenna 10 can achieve the radiation characteristics shown in Fig. 5. Fig. 5 is a diagram showing an example of the radiation characteristics of the antenna according to the first embodiment. As shown in Fig. 5, the antenna 10 can achieve directivity in which the radiated power is relatively strong in directions at a predetermined angle different from 90° with respect to the axial direction.

[0053] Furthermore, by appropriately setting the distances L12 and L13, the antenna 10 can also achieve the radiation characteristics shown in Figures 6(A), 6(B), and 6(C). Figures 6(A), 6(B), and 6(C) are diagrams each showing an example of the radiation characteristics. Figure 6(A) shows the case where the distances L12 and L13 are set to 2λ. g1 The radiation characteristics are shown in Fig. 6(B) when the distances L12 and L13 are set to λ g1 The radiation characteristics are shown in Fig. 6(C) when the distances L12 and L13 are set to λ g1 This is the radiation characteristic when

[0054] As shown in FIG. 6(A), the distances L12 and L13 are set to 2λ. g1 By setting the distances L12 and L13 to λ / 3, it is possible to achieve the same level of radiation intensity in the axial direction and in any direction other than the axial direction, including the direction perpendicular to the axial direction. g1 By setting the distances L12 and L13 to λ / 4, it is possible to achieve a radiation characteristic that is relatively strong in the axial direction and relatively weak in the direction perpendicular to the axial direction. g1 By doing so, it is possible to realize a radiation characteristic in which the radiation is relatively weak in the axial direction and relatively strong in the direction perpendicular to the axial direction.

[0055] These are just examples, and as shown in these examples, the distances L12 and L13 are g1By multiplying the directivity by a predetermined multiple (a positive real number), the antenna 10 can easily and more reliably achieve the desired directivity.

[0056] In this case, as described above, the radiated power can be adjusted by appropriately setting the width G241 of the slit 241, the width G242 of the slit 242, and the width G243 of the slit 243. This allows the antenna 10 to easily and reliably achieve the desired directivity with the desired radiated power.

[0057] In the above example, the distances L12 and L13 are distances in the axial direction, but the distances L12 and L13 are determined taking into consideration the thickness of the outer conductor 220. That is, the wavelength λ g1 The distance set using is determined by the sum of the axial distance and the thickness of the outer conductor 220. This allows the antenna 10 to achieve the desired directivity with higher accuracy.

[0058] Slits 241, 242, and 243 do not necessarily have to be filled with a dielectric, but may be filled with a dielectric as shown in Figures 1, 2, and 3. Slit 241 is filled with dielectric 241DE, slit 242 is filled with dielectric 242DE, and slit 243 is filled with dielectric 243DE. By providing such dielectrics, the shapes of slits 241, 242, and 243 can be stably maintained. This improves the reliability of antenna 10.

[0059] Furthermore, the antenna 10 does not have a configuration in which multiple individually formed coaxial cables are connected in phase or opposite phase, so it can achieve high structural strength, which further improves the reliability of the antenna 10.

[0060] (Protective structure of antenna 10) The dielectric 31 covers the outer peripheral surface of the outer conductor 220. As a result, the antenna 10 can protect the antenna functional section including the outer conductor 200 from the external environment by the dielectric 31 without adversely affecting the radiation of electromagnetic waves from the slits 241, 242, and 243. This improves the reliability of the antenna 10.

[0061] One axial end of the dielectric 31 is held by the flange of the outer conductor 221, and the other axial end of the dielectric 31 is held by the flange of the outer conductor 222. That is, the dielectric 31 is held by being sandwiched between the flanges of the outer conductor 221 and the outer conductor 222. This allows the dielectric 31 to be stably fixed.

[0062] Waterproof film 32 covers the outer peripheral surface of dielectric 31. Waterproof film 32 is made of a non-conductive material. This improves the waterproofness of the antenna functional section of antenna 10 without adversely affecting the radiation of electromagnetic waves from slits 241, 242, and 243. This further improves the reliability of antenna 10.

[0063] At this time, the waterproof film 32 is fixed using the flanges of the outer conductor 221 and the outer conductor 222. This allows the antenna function section to be more securely covered by the waterproof film 32. This further improves the waterproofness of the antenna function section and the reliability of the antenna 10.

[0064] (Connection configuration of antenna 10 to external coaxial cable) As described above, the outer conductor 221 has the opening 2210. The first end 21E1 of the inner conductor 21 is exposed through this opening 2210. The outer conductor of the outer coaxial cable 91 abuts against and is fixed to the outer conductor 221. The inner conductor 21o1 of the outer coaxial cable 91 protrudes as far as the opening 2210, and extends to a position close to the first end 21E1 of the inner conductor 21.

[0065] The inner conductor 21 and the inner conductor 21o1 are connected by a conductive bonding material such as solder. In this case, the opening 2210 makes it possible to easily supply the conductive bonding material from the outside to the area adjacent to the inner conductor 21o1 and the inner conductor 21. This makes it possible to easily and more reliably bond the antenna 10 and the external coaxial cable 91.

[0066] In this case, it is preferable to place a dielectric on the side of the outer conductor 221 in the vicinity of the inner conductor 21 and the inner conductor 21o1 so that the conductive bonding material does not come into contact with the outer conductor 221. This makes it possible to prevent a short circuit between the inner conductors 21, 21o1 and the outer conductor 221 due to the conductive bonding material.

[0067] Similarly, the outer conductor 222 has an opening 2220. The second end 21E2 of the inner conductor 21 is exposed through this opening 2220. The outer conductor of the outer coaxial cable 92 abuts against and is fixed to the outer conductor 222. The inner conductor 22o2 of the outer coaxial cable 92 protrudes as far as the opening 2220, and extends to a position close to the second end 21E2 of the inner conductor 21.

[0068] The inner conductor 21 and the inner conductor 21o2 are connected by a conductive bonding material such as solder. In this case, the opening 2220 makes it possible to easily supply the conductive bonding material from the outside to the area adjacent to the inner conductor 21o2 and the inner conductor 21. This makes it possible to easily and more reliably bond the antenna 10 and the external coaxial cable 92.

[0069] In this case, it is preferable to place a dielectric on the side of the outer conductor 222 in the vicinity of the inner conductor 21 and the inner conductor 21o2 so that the conductive bonding material does not come into contact with the outer conductor 222. This makes it possible to prevent a short circuit between the inner conductors 21, 21o2 and the outer conductor 222 due to the conductive bonding material.

[0070] The openings 2210 and 2220 may have any shape as long as they open a portion of the outer conductor 221 and the outer conductor 222 in the circumferential direction. This suppresses radiation of electromagnetic waves from the openings 2210 and 2220. That is, the antenna 10 can be connected to the coaxial cables 91 and 92 while suppressing unnecessary radiation of electromagnetic waves. In this case, impedance mismatch can be suppressed by adjusting the portions having the openings 2210 and 2220 to have the same impedance as the coaxial lines.

[0071] [Second embodiment] An antenna according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 7(A) is a side cross-sectional view showing the configuration of the antenna according to the second embodiment, and Fig. 7(B) is an enlarged plan view of an antenna function section in the antenna according to the second embodiment.

[0072] 7(A) and 7(B), the antenna 10A according to the second embodiment differs from the antenna 10 according to the first embodiment in that it includes a plurality of slits 41 and 42. Other configurations of the antenna 10A are the same as those of the antenna 10, and a description of similar parts will be omitted.

[0073] 7(A) and 7(B), the antenna 10A has a plurality of slits 41 and 42 in the outer conductor 220. The slits 41 and 42 are openings formed in the outer conductor 220, and each opening has a rectangular shape.

[0074] The slits 41 and 42 are formed at different positions in the axial direction of the coaxial line. The long sides of the slits 41 and 42 form a predetermined angle with respect to the axial direction of the coaxial line. The predetermined angle is an angle that is neither 0° (parallel to the axial direction) nor 90° (orthogonal to the axial direction).

[0075] The length L41 of the long side of the slit 41 and the length L42 of the long side of the slit 42 are set to a value that is different from the frequency (wavelength λ ) of the electromagnetic waves radiated from the slits 241, 424, and 243. g2 ) More specifically, the lengths L41 and L42 are determined based on λ g2 / 2.

[0076] With this configuration, slits 41 and 42 can emit electromagnetic waves having frequencies different from those of the electromagnetic waves emitted from slits 241, slits 424, and slits 243.

[0077] This allows the antenna 10A to radiate electromagnetic waves at multiple frequencies.

[0078] (Outer conductor derivative configuration) In each of the above-described embodiments, the outer conductor may have the following configuration: Figures 8(A) and 8(B) are diagrams showing derived configurations of the outer conductor.

[0079] The outer conductor 220A shown in Fig. 8(A) has a shaping slit SL. The shaping slit SL reaches both ends of the outer conductor 220A in the extending direction.

[0080] In this configuration, the outer conductor 220A can be formed by bending a plate-like member, which allows the outer conductor 220A to be manufactured more cheaply and easily than by cutting a cylindrical shape out of a metal rod.

[0081] 8(B) includes a plurality of shaping slits SL1 and SL2. The plurality of shaping slits SL1 and SL2 reach both ends of the outer conductor 220A in the extending direction. In this case, the outer conductor 220B is composed of an outer conductor 220B1 and an outer conductor 220B2.

[0082] In this configuration, the outer conductor 220B (the outer conductor B1 and the outer conductor 220B2) can be formed by bending a plate-like member, which allows the outer conductor 220B to be manufactured more cheaply and easily than by cutting a cylindrical shape out of a metal rod.

[0083] It should be noted that the examples shown in FIGS. 8(A) and 8(B) are merely examples, and the number of shaping slits formed in the outer conductor is not limited to these.

[0084] Furthermore, since the shaping slits of this shape are parallel to the current flowing through the outer conductor, they do not function as radiating elements. Therefore, no radio waves leak from the shaping slits. This improves ease of manufacturing without degrading the radiation characteristics.

[0085] [Third embodiment] An antenna according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 9(A) is a plan view showing the configuration of the antenna according to the third embodiment, and Fig. 9(B) is a side cross-sectional view showing the configuration of the antenna according to the third embodiment. Fig. 10 is a perspective view showing the appearance of the antenna according to the third embodiment.

[0086] 9(A), 9(B), and 10, an antenna 10C according to the third embodiment differs from the antenna 10 according to the first embodiment in the structure of the outer conductor 220C. Other configurations of the antenna 10C are similar to those of the antenna 10, and descriptions of similar parts will be omitted. Also, the connection portions between both axial ends of the antenna 10C and the coaxial cable 91 are shown in a simplified manner, and may be similar to those of the above-described embodiments or may have other connection structures.

[0087] The outer conductor 220C of the antenna 10C has a rectangular parallelepiped shape with an internal space extending along the axial direction of the inner conductor 21. With this structure, the outer conductor 220C has a flat plate-shaped first wall F2201. More specifically, the outer conductor 220C is formed by overlapping a first part 2201 and a second part 2202, each of which has a recess. The outer conductor 220C may also be formed into a rectangular tube shape by bending a single metal plate.

[0088] A plurality of slits 511, 512, 521, and 522 are formed in the first wall F2201 of the outer conductor 220C. The slits 511, 512, 521, and 522 are openings formed in the outer conductor 220B, and each opening has a rectangular shape. The slits 511 and 512 form a pair, and the slits 521 and 522 form a pair.

[0089] In the direction in which the coaxial line extends, the slits 511 and 512 are disposed between the slits 521 and 522 .

[0090] Slits 511 and 512 are formed at different positions in the axial direction of the coaxial line. The long sides of slits 511 and 512 form a predetermined angle with respect to the axial direction of the coaxial line. The predetermined angle is an angle that is neither 0° (parallel to the axial direction) nor 90° (orthogonal to the axial direction).

[0091] The length of the long sides of the slits 511 and 512 is determined by the frequency (wavelength λ g3 ) More specifically, the length of the long sides of the slits 511 and 512 is determined based on λ g3 / 2.

[0092] The distance SP51 between the slits 511 and 512 in the axial direction of the coaxial line is set to the frequency (wavelength λ g3 ) More specifically, the interval SP51 between the slit 511 and the slit 512 is determined based on (2n+1)λ g3 / 2, where n is an integer greater than or equal to 0.

[0093] Slits 521 and 522 are formed at different positions in the axial direction of the coaxial line. The long sides of slits 521 and 522 form a predetermined angle with respect to the axial direction of the coaxial line. The predetermined angle is an angle that is neither 0° (parallel to the axial direction) nor 90° (orthogonal to the axial direction).

[0094] The length of the long sides of the slits 521 and 522 is determined by the frequency (wavelength λ g4 ) is determined based on the wavelength λ g4 is the wavelength λ g3 More specifically, the length of the long sides of the slits 511 and 512 is shorter than λ g4 / 2.

[0095] The distance SP52 between the slit 511 and the slit 512 in the axial direction of the coaxial line is set to the frequency (wavelength λ g4More specifically, the interval SP52 between the slits 521 and 522 is determined based on (2n+1)λ g4 / 2, where n is an integer greater than or equal to 0.

[0096] With this configuration, electromagnetic waves of the third frequency can be emitted from the pair of slits 511 and 512, and electromagnetic waves of the fourth frequency (a frequency different from the third frequency (in this embodiment, a frequency higher than the third frequency)) can be emitted from the pair of slits 521 and 522. This allows antenna 10C to emit electromagnetic waves of multiple frequencies.

[0097] With the pair of slits 511 and 512 in the positional relationship described above, the electromagnetic wave of the third frequency has a predetermined level of directivity in a direction perpendicular to the extension direction of antenna 10C. Similarly, with the pair of slits 521 and 522 in the positional relationship described above, the electromagnetic wave of the fourth frequency has a predetermined level of directivity in a direction perpendicular to the extension direction of antenna 10C.

[0098] 11(A) and 11(B) are diagrams showing an example of the radiation characteristics of the antenna according to the third embodiment. In FIGS. 11(A) and 11(B), the third frequency is 2.4 GHz and the fourth frequency is 5.0 GHz. As shown in FIGS. 11(A) and 11(B), the antenna 10C can radiate electromagnetic waves of two different frequencies at a predetermined level with a predetermined directivity in a direction perpendicular to the extension direction of the antenna 10C.

[0099] In this embodiment, the electromagnetic waves of two different frequencies are radiated, but the above-described configuration can also be applied to the case where electromagnetic waves of three or more different frequencies are radiated. For example, when electromagnetic waves of three different frequencies are radiated, three sets of slits corresponding to the respective frequencies (wavelengths) may be formed in the outer conductor 220B.

[0100] Furthermore, the intervals between the plurality of slits that radiate one type of electromagnetic wave are not limited to the intervals described above, and may be set in accordance with the desired radiation characteristics.

[0101] Furthermore, in the configuration of antenna 10C, a pair of slits 521 and 522 are formed so as to sandwich a pair of slits 511 and 512 therebetween. This allows antenna 10C to have a short axial length even when radiating multiple frequencies. Note that antenna 10C is configured such that slits 521 and 522, which radiate relatively high frequencies, sandwich slits 511 and 512, which radiate relatively low frequencies. However, this relationship may be reversed, and can be appropriately selected depending on the relationship between the wavelengths of the electromagnetic waves radiated by each slit.

[0102] [Fourth embodiment] An antenna according to a fourth embodiment of the present invention will be described with reference to the drawings. Fig. 12(A) is a plan view showing the configuration of the antenna according to the fourth embodiment, and Fig. 12(B) is a side cross-sectional view showing the configuration of the antenna according to the fourth embodiment.

[0103] 12(A) and 12(B), the antenna 10D according to the fourth embodiment differs from the antenna 10C according to the third embodiment in the configuration of the outer conductor 220D. The other configuration of the antenna 10D is the same as that of the antenna 10C, and a description of the similar parts will be omitted.

[0104] The outer conductor 220D of the antenna 10C has a first wall F2201 and a second wall F2202 that are perpendicular to each other. The first wall F2201 has a slit 511 and a slit 512. The second wall F2202 has a slit 521 and a slit 522.

[0105] With this configuration, antenna 10D can set the relationship between the directivity of the electromagnetic waves radiated by the pair of slits 511 and 512 and the directivity of the electromagnetic waves radiated by the pair of slits 511 and 512 to be rotated 90° around the axial direction of the coaxial line as the central axis.

[0106] For example, the relationship between the direction of strongest electromagnetic waves radiated by the pair of slits 511 and 512 and the direction of strongest electromagnetic waves radiated by the pair of slits 511 and 512 can be set to rotate by 90° around the axial direction of the coaxial line. Alternatively, the relationship between the direction of weakest electromagnetic waves radiated by the pair of slits 511 and 512 and the direction of weakest electromagnetic waves radiated by the pair of slits 511 and 512 can be set to rotate by 90° around the axial direction of the coaxial line.

[0107] In this way, by using the configuration of antenna 10D, it is possible to realize a wider variety of electromagnetic wave directivity relationships for electromagnetic waves of multiple frequencies.

[0108] In the third and fourth embodiments, the outer conductor is rectangular, but it is not limited to a rectangular shape and may be other polygonal shapes.

[0109] [Fifth embodiment] (Communication System Configuration) 12(A), 12(B), 12(C), 14(A), 14(B), 14(C), and 15 are configuration diagrams of communication systems according to embodiments of the present invention. Each shows a different connection configuration, but these can be combined. In the following explanation, antenna 10 is used as an example, but this can also be replaced with antenna 10A.

[0110] A communication system 1A in FIG. 13(A) includes a plurality of antennas 10, a communication device 90, and a plurality of coaxial cables 91.

[0111] The communication device 90 is connected to a first antenna 10 via a first coaxial cable 91. The first antenna 10 is connected to a second antenna 10 via a second coaxial cable 91. The second antenna 10 is connected to a third antenna 10 via a third coaxial cable 91. The third antenna 10 is connected to a fourth coaxial cable 91. In other words, the communication device 90 and the multiple antennas 10 are connected in series via multiple coaxial cables 91, with the communication device 90 as one end of a communication line.

[0112] The length L91 of the coaxial cable 91 is greater than the length L10 of the antenna 10. Note that the length L91 of the coaxial cable 91 may be less than or equal to the length L10 of the antenna 10. In other words, the length L91 of the coaxial cable 91 can be set as appropriate.

[0113] With this configuration, the communication system 1A can place the communication device 90 at a desired position and place multiple antennas 10 at desired positions, and connect them with multiple coaxial cables 91. Therefore, it is possible to appropriately place the communication system 1A according to the environment in which it is deployed.

[0114] 13(B) includes a plurality of antennas 10, a communication device 90, a plurality of coaxial cables 91, and a termination resistor (absorption resistor) 99. The communication system 1B differs from the communication system 1A in that the termination resistor 99 is connected to the open end of the fourth coaxial cable 91. Furthermore, the plurality of coaxial cables 91 of the communication system 1B are flexible. In other words, the plurality of coaxial cables 91 of the communication system 1B are deformable.

[0115] With this configuration, in the communication system 1B, appropriate termination processing is performed at the open end of the coaxial cable 91. This makes it possible to realize a communication system with even lower loss.

[0116] Furthermore, since the multiple coaxial cables 91 are deformable, more diverse arrangements are possible. For example, if a similar communication system were to be constructed using a waveguide, advance preparations such as manufacturing the waveguide in a curved form would be necessary. However, in the communication system 1B, since the coaxial cables 91 are deformable, the coaxial cables 91 can be deformed according to the shape of the deployment location after arriving at the deployment location of the communication system 1B. Therefore, the communication system 1B can be deployed with greater flexibility. In particular, if the length L91 of the coaxial cables 91 is longer than the length L10 of the antenna 10, the deformable portion becomes relatively larger. Therefore, the communication system 1B can be deployed in even more diverse ways.

[0117] 13(C) includes a plurality of antennas 10, a communication device 90, and a plurality of coaxial cables 91. The communication system 1C differs from the communication system 1A in that the plurality of antennas 10 are arranged in two directions from the communication device 90 via the coaxial cables 91.

[0118] With this configuration, the communication system 1C can transmit radio waves in multiple directions from the communication device 90 and radiate them from multiple antennas 10. Although the configuration of the communication system 1C has been shown as an example of a two-way configuration, this configuration can also be applied to three or more directions.

[0119] 14A includes a plurality of antennas 10, a plurality of communication devices 90, and a plurality of coaxial cables 91. The communication system 1D differs from the communication system 1A in that the communication system 1D includes a communication device 90 at both ends.

[0120] With this configuration, the communication system 1D can transmit radio waves from a plurality of communication devices and radiate them from a plurality of antennas 10.

[0121] 14(B) includes a plurality of antennas 10, a plurality of communication devices 90, a plurality of coaxial cables 91, and a termination resistor 99. The communication system 1E differs from the communication system 1A in that the plurality of communication devices 90 and the plurality of antennas 10 are alternately connected using a plurality of coaxial cables 91, and the termination resistor 99 is connected to the open end of the coaxial cables 91.

[0122] With this configuration, the communication system 1E can transmit radio waves from multiple communication devices and radiate them from multiple antennas 10. Furthermore, the communication system 1E can properly terminate the open ends of the coaxial cables 91, thereby achieving a lower-loss communication system.

[0123] A communication system 1F in FIG. 14(C) includes a plurality of antennas 10, a plurality of communication devices 90, a plurality of coaxial cables 91, and a combiner 98.

[0124] The multiple communication devices 90 are connected to a combiner 98. The combiner 98 is connected to a first antenna 10 through a first coaxial cable 91. The first antenna 10 is connected to a second antenna 10 through a second coaxial cable 91. The second antenna 10 is connected to a third antenna 10 through a third coaxial cable 91. The third antenna 10 is connected to a fourth coaxial cable 91.

[0125] With this configuration, the communication system 1F can combine and transmit radio waves from a plurality of communication devices and radiate them from a plurality of antennas 10.

[0126] The communication system 1G in Fig. 15 includes a plurality of antennas 10, a communication device 90, a plurality of coaxial cables 91, and a termination resistor 99. The communication system 1G differs from the communication system 1C in that the plurality of antennas 10 are arranged on different floors of a building, and in that the communication system 1G includes a termination resistor 99. Note that Fig. 15 shows an example of arrangement on each floor, and the configuration of this example can be applied as long as the antennas 10 are arranged on multiple floors.

[0127] The communication device 90 is placed on the first floor above ground, and two coaxial cables 91 are connected to the communication device 90. The antenna 10 on the first floor above ground is connected to the communication device 90 by the coaxial cable 91. The antennas 10 on other floors above ground are connected to the antenna 10 on the first floor above ground in turn by coaxial cables 91. That is, starting from the communication device 90, the antennas 10 on multiple floors above ground (in the case of FIG. 15, the first floor above ground, the second floor above ground, and the Mth floor above ground) are connected in turn using multiple coaxial cables 91. A termination resistor 99 is connected to the antenna 10 at the end point.

[0128] The antenna 10 on the first basement floor is connected to the communication device 90 by a coaxial cable 91. The antennas 10 on the other basement floors are successively connected to the antenna 10 on the first basement floor by coaxial cables 91. That is, starting from the communication device 90, the antennas 10 on multiple basement floors (the first basement floor and the Nth basement floor in the case of FIG. 15) are successively connected using multiple coaxial cables 91. A termination resistor 99 is then connected to the antenna 10 at the end point.

[0129] With this configuration, the communication system 1G can transmit radio waves from the communication device 90 to multiple floors above ground and underground, and radiate them from multiple antennas 10.

[0130] As described above, by employing the communication system of this embodiment, it is possible to appropriately arrange the communication device and antenna according to the deployment environment and the radiation range of the radio waves.

[0131] The configurations of the above-described embodiments can be combined as appropriate, and effects according to each combination can be achieved. [Explanation of symbols]

[0132] 1A, 1B, 1C, 1D, 1E, 1F, 1G: Communication Systems 10, 10A, 10C, 10D: Antenna 21: Inner conductor 21E1: 1st end 21E2: 2nd end 23, 241DE, 242DE, 243DE, 31: Dielectric 220, 220A, 220B, 220B1, 220B2, 220C, 220D, 221, 222: outer conductor 241, 242, 243: Slits 2210, 2220: Opening 32: Waterproof film 41, 42, 511, 512, 521, 522: Slits 90:Communication device 91: Coaxial cable 98:Synthesizer 99: Termination resistor

Claims

1. an inner conductor; a cylindrical outer conductor arranged along the extending direction of the inner conductor and spaced apart from the inner conductor; a plurality of first slits formed independently of one another at positions spaced apart from one another in the extending direction of the outer conductor; An antenna comprising: The formation intervals of the plurality of first slits are: When a wavelength in a transmission path formed by the inner conductor and the outer conductor is λ g1 , the lengths λ g1 and λ g1 / 2 are different. antenna.

2. An inner conductor; a cylindrical outer conductor arranged along the extending direction of the inner conductor and spaced apart from the inner conductor; a plurality of first slits formed independently of one another at positions spaced apart from one another in the extending direction of the outer conductor; a third slit formed in the outer conductor and reaching both ends in the extending direction; An antenna comprising:

3. 3. The antenna according to claim 1 or claim 2, a first dielectric material filled in the plurality of first slits; antenna.

4. 4. The antenna according to claim 1, wherein: a second dielectric covering an outer circumferential surface of the outer conductor; antenna.

5. 5. The antenna of claim 4, a waterproof film covering an outer circumferential surface of the second dielectric; antenna.

6. 6. The antenna according to claim 1, The formation intervals of the plurality of first slits are different from one another. antenna.

7. 7. The antenna according to claim 1, a plurality of second slits formed in the outer conductor and extending at an angle other than 0° and 90° with respect to the extending direction; antenna.

8. 8. The antenna of claim 7, The length of the plurality of second slits is The length is half of a wavelength different from the wavelength of the electromagnetic wave radiated by the first slit. antenna.

9. An inner conductor; a cylindrical outer conductor arranged along the extending direction of the inner conductor and spaced apart from the inner conductor; a plurality of first slits formed independently of one another at positions spaced apart from one another in the extending direction of the outer conductor; An antenna comprising: the plurality of first slits extend at an angle other than 0° and 90° with respect to the extending direction of the outer conductor; the plurality of first slits are formed in the extending direction at intervals of wavelength×(2n+1) / 2 (n is an integer equal to or greater than 0) in a transmission path formed by the inner conductor and the outer conductor; antenna.

10. An inner conductor; a cylindrical outer conductor arranged along the extending direction of the inner conductor and spaced apart from the inner conductor; a plurality of first slits formed independently of one another at positions spaced apart from one another in the extending direction of the outer conductor; An antenna comprising: the plurality of first slits extend at an angle other than 0° and 90° with respect to the extending direction of the outer conductor; the plurality of first slits include a plurality of third slits that form pairs and a plurality of fourth slits that form pairs, The lengths of the plurality of third slits in the long side direction are different from the lengths of the plurality of fourth slits in the long side direction, The formation intervals of the plurality of third slits and the formation intervals of the plurality of fourth slits are different. antenna.

11. 11. The antenna of claim 10, the plurality of fourth slits are formed at positions sandwiching the plurality of third slits in the extending direction of the outer conductor; antenna.

12. 12. The antenna according to claim 10 or 11, the outer conductor includes a plurality of walls each having a flat surface; the plurality of third slits and the plurality of fourth slits are formed in different walls of the plurality of walls; antenna.

13. An antenna according to any one of claims 1 to 12, an antenna function unit including the inner conductor, the outer conductor, and the first slit; a coaxial connector connected to the antenna function unit; An antenna comprising:

14. 14. The antenna of claim 13, The outer conductor of the coaxial connector is an opening through which a part of the inner conductor in the circumferential direction is exposed to the outside; antenna.

15. an antenna according to claim 13 or claim 14; a coaxial cable to which the coaxial connector is connected; a communication device connected to the coaxial cable; A communication system comprising:

16. 16. The communication system of claim 15, a plurality of the coaxial cables and the communication devices; a plurality of coaxial cables connected to the coaxial connectors at both ends of the antenna, a plurality of communication devices connected to the plurality of coaxial cables, respectively; Communication system.

17. 16. The communication system of claim 15, a plurality of the antennas, the coaxial cables, and the communication devices; The plurality of antennas and the plurality of communication devices are connected in series using a plurality of coaxial cables. Communication system.

18. A communication system according to any one of claims 15 to 17, an absorbing resistor connected to an open end of the coaxial cable; Communication system.

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