JP2011015330A - Waveguide structure and waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waveguide structure and waveguide in which electromagnetic waves in high frequency domains equal to or higher than millimeter wave domains can be transmitted with low loss.SOLUTION: The waveguide structure 100 is configured by combining dielectric wires 101 each having a shape of square pole whose cross section is square, and has a wood pile structure. The object having such a cyclic structure has a photonic crystal structure. A photonic band gap is formed, so as not to transmit electromagnetic waves of a predetermined frequency. The waveguide structure 100 is formed only from the dielectric wires 101, and is used for forming the waveguide with no conductor loss.

Description

  The present invention relates to a waveguide structure for transmitting millimeter wave band electromagnetic waves, and a waveguide formed using the waveguide structure.

  Conventionally, a waveguide for transmitting electromagnetic waves is configured by combining a conductor and a dielectric. In the case of sealed waveguides except those that actively open and leak electromagnetic waves in the surrounding space such as antennas, a conductor is used on the outer wall of the waveguide to confine the electromagnetic waves inside the waveguide. It has been.

  For example, a coaxial cable described in Patent Document 1 has been conventionally used as a waveguide for hermetically transmitting such electromagnetic waves. An example of the coaxial cable is shown in FIG. The coaxial cable 900 has a core 903 formed by covering a center conductor 901 with a dielectric layer 902. A conductor layer 906 made of a metal foil 904 and an outer conductor layer 905 is formed around the core 903, and the outer periphery thereof is covered with a jacket 907.

JP 2007-179985 A

  However, when the outer wall of the waveguide is formed using a conductor, there is a problem that a large transmission loss occurs in the conductor portion. In general, as main losses generated in the waveguide, there are a conductor loss generated in the conductor part and a dielectric loss generated in the dielectric part. When electromagnetic waves propagate on the conductor surface, an eddy current is generated on the conductor surface due to the skin effect, and the conductor loss is caused by the generation of the eddy current. The conductor loss becomes larger as the electromagnetic wave has a higher frequency. In particular, in the millimeter wave region, the conductor loss exceeds the dielectric loss. That is, in the high frequency region, the conductor loss becomes the dominant transmission loss of the waveguide.

  When a circuit is configured in the high frequency region above the millimeter wave region, the loss generated in the waveguide connecting each module such as an oscillator, a mixer, an amplifier, etc. is a magnitude that cannot be ignored in the circuit design in total. . Most of this loss is due to conductor loss. Thus, there is a problem that a large conductor loss occurs in the waveguide in the high frequency region.

  Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide a waveguide structure and a waveguide that can transmit electromagnetic waves in a high frequency region above the millimeter wave region with low loss.

  A first aspect of the waveguide structure according to the present invention is a waveguide structure that transmits electromagnetic waves in a high frequency region of a millimeter wave region or more, and a wire made of a dielectric has an interval equal to the width of the wire. The first layer formed in parallel and the wire is formed in parallel with an interval equal to the width of the wire in a direction orthogonal to the wire forming the first layer. The second layer and the wire are arranged at an interval equal to the width of the wire in a direction parallel to the wire forming the first layer, and the wire of the first layer is disposed. A third layer formed to be disposed at a position corresponding to a non-existing portion, and the wire is arranged at an interval equal to the width of the wire in a direction parallel to the wire forming the second layer, and And a fourth layer disposed at a position corresponding to the interval of the second layer. Characterized in that it comprises a periodic structure of a layer structure as a unit cycle 1.5 cycles or more.

  A second aspect of the waveguide structure of the present invention is a waveguide structure that transmits electromagnetic waves in a high frequency region of the millimeter wave region or more, and alternately knitting two or more wires made of a dielectric material in a direction orthogonal to each other. A laminated structure comprising a first layer of a braided structure and a second layer formed between the wires that are formed in the braided structure and in which the wire does not overlap the wire that forms the first layer A periodic structure having a unit period of 1.5 or more is provided.

  A third aspect of the waveguide structure of the present invention is characterized in that the laminated structure is formed in a cylindrical shape on the surface of a linear conductor.

  In another aspect of the waveguide structure according to the present invention, the wire has a cross-sectional shape of any one of a circle, an ellipse, and a polygon.

  A first aspect of the waveguide according to the present invention is a coaxial waveguide including a cylindrical inner wall portion and a cylindrical outer wall portion whose inner diameter is larger than the outer diameter of the inner wall portion. The portion and the outer wall portion are formed of the waveguide structure according to the third aspect.

  A second aspect of the waveguide of the present invention is a waveguide in which a cross section is rectangular and four wall surfaces are surrounded by a plane parallel to the transmission direction, and the four wall surfaces are described in the first or second aspect. It is characterized by being formed of a waveguide structure.

  As described above, according to the present invention, it is possible to provide a waveguide structure and a waveguide that can transmit electromagnetic waves in a high frequency region of the millimeter wave region or higher with low loss.

It is a perspective view showing a schematic structure of a waveguide structure concerning a 1st embodiment of the present invention. 1 is a perspective view of a waveguide according to an embodiment of the present invention. It is sectional drawing of the conventional waveguide. It is a graph which shows the frequency dependence of the transmission loss of the conventional waveguide. It is a graph which shows the electric field energy distribution of the electromagnetic waves which penetrate | invade from the surface of the waveguide structure of 1st Embodiment. It is a graph which shows the relationship between the dielectric loss tangent tan-delta of the waveguide structure of 1st Embodiment, and the penetration | invasion length attenuate | damped to 1 / e. It is a perspective view which shows schematic structure of the waveguide structure which concerns on the 2nd and 3rd embodiment of this invention. It is a top view which shows schematic structure of the waveguide structure concerning the 4th Embodiment of this invention. It is explanatory drawing which shows the preparation methods of the waveguide structure which concerns on 4th Embodiment. It is a perspective view which shows the conventional coaxial cable.

  A waveguide structure according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. Each component having the same function is denoted by the same reference numeral for simplification of illustration and description.

  First, it will be described below that when a waveguide formed of a conductor is used, a conductor loss becomes a dominant loss in the millimeter wave region. When a typical coaxial cable 10 (coaxial cable conforming to MIL-C-17 / 151) having a cross section as shown in FIG. 3A is used as a waveguide used in the millimeter wave region, the coaxial cable is used. The frequency dependence of the transmission loss at 10 is shown in FIG. FIG. 4 shows that the transmission loss increases approximately in proportion to the square root of the frequency f, where f is the frequency of the electromagnetic wave to be transmitted.

ここで、σは導体（銅）の導電率を表す。これより、図４に示した同軸ケーブルの伝送損失１１は、式（１）で与えられる表皮抵抗に依存した損失が支配的であることがわかる。 On the other hand, the skin resistance (referred to as R _s ) on the conductor surface is proportional to the square root of the frequency f as shown in the following equation.

Here, σ represents the electrical conductivity of the conductor (copper). From this, it can be seen that the transmission loss 11 of the coaxial cable shown in FIG. 4 is dominated by the loss depending on the skin resistance given by the equation (1).

  Next, in the transmission loss 11 of the coaxial cable 10 shown in FIG. 4, each ratio of the conductor loss and the dielectric loss will be described below. A case where a signal having a frequency of 60 GHz used in a millimeter-wave wireless LAN is used as a high-frequency signal and transmitted to the coaxial cable 10 will be described as an example.

また、同軸ケーブルの誘電体損失（Ｌ_ｄ［ｍＷ／ｍ］とする）は次式で与えられる。

ここで、
Ｅ_０：入力波の実効値［Ｖ／ｍ］
Ｚ_０：特性インピーダンス［Ω］
ａ：同軸ケーブル１０の内部導体の外径［ｍｍ］
ｂ：同軸ケーブル１０の誘電体層の外径［ｍｍ］
ε_ｒ：比誘電率
ｔａｎδ：誘電正接 The conductor loss (referred to as L _m [mW / m]) of the coaxial cable 10 is given by the following equation using the skin resistance R _s of the equation (1).

Further, the dielectric loss (L _d [mW / m]) of the coaxial cable is given by the following equation.

here,
E ₀ : RMS value of input wave [V / m]
Z ₀ : Characteristic impedance [Ω]
a: Outer diameter [mm] of the inner conductor of the coaxial cable 10
b: outer diameter [mm] of the dielectric layer of the coaxial cable 10
ε _r : dielectric constant tan δ: dielectric loss tangent

When the conductor and the dielectric used for the coaxial cable 10 are copper and PTFE (polytetrafluoroethylene), respectively, the following parameter values at the frequency f = 60 GHz are set according to the MIL-C-17 / 151 standard as follows: Numerical values can be used.
E ₀ = 1 [V / m]
Z ₀ = 50 [Ω]
a = 0.288 / 2
b = 0.940 / 2
ε _r = 2.0
tan δ = 2.0 × 10 ⁻⁴
σ = 5.8 × 10 ⁷
However, the vacuum dielectric constant ε ₀ = 8.85 × 10 ⁻¹² [F / m] and the vacuum permeability μ ₀ = 4π × 10 ⁻⁷ .

Substituting the above numerical values into the equations (2) and (3), the conductor loss L _m and the dielectric loss L _d are given as follows.
L _m = 1460 [mW / m]
L _d = 1.5 [mW / m]

このように、動作周波数６０ＧＨｚでは導体損失が全損失のほとんどを占めていることがわかる。 As a result, the ratio of the conductor loss 11 of the coaxial cable 10 at the operating frequency of 60 GHz to the total loss is as follows.

Thus, it can be seen that the conductor loss accounts for most of the total loss at the operating frequency of 60 GHz.

  As described above, generally, in the millimeter wave region, most of the loss of the waveguide is a conductor loss. When the rectangular waveguide 20 having a rectangular cross section as shown in FIG. 3B is used instead of the coaxial cable, the ratio of the conductor loss to the total transmission loss in the millimeter wave region is further 100%. Get closer to. When the waveguide is used, since there is no electric field concentration as in the coaxial cable, the transmission loss 21 becomes lower as shown in FIG. Thus, in the case of a waveguide configured using metal, conductor loss cannot be avoided. Therefore, a low-loss waveguide can be provided by realizing a waveguide with low conductor loss in the millimeter wave region.

  A waveguide structure according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing a waveguide structure 100 according to this embodiment. The waveguide structure 100 of the present embodiment is configured by combining wire rods 101 having a quadrangular prism shape with a square cross section, and has a wood pile structure. The waveguide structure 100 having such a woodpile structure can be used to form a waveguide having no conductor loss. An example of a waveguide formed using the waveguide structure 100 is shown in FIG. FIG. 2 is a perspective view showing a waveguide 110 formed using the waveguide structure 100 of the present embodiment.

  The wood pile structure of the waveguide structure 100 can be formed as follows. First, the wire 101 is arranged in parallel to a predetermined direction (X-axis direction shown in FIG. 1) to form a first layer structure. At this time, the adjacent wire rods 101 are arranged with a gap having the same width as that of the wire rod 101. Next, the second layer structure is formed on the first layer structure by arranging the wires 101 in parallel in the Y-axis direction perpendicular thereto. Also at this time, a gap having the same width as that of the wire 101 is provided between the adjacent wires 101. The third layer is arranged again in the same X-axis direction as the first layer, but the position in the X-axis direction where the wire 101 is not arranged in the layer structure of the first layer, that is, the first layer The wire 101 is arranged at a position corresponding to a portion where the wire 101 is not arranged. Similarly, the wire material 101 of the 4th layer is also arrange | positioned in the clearance gap between the wire materials 101 of the 2nd layer.

  In the layer structure up to the fourth layer, one unit of a woodpile structure is formed. Hereinafter, this 1-unit woodpile structure is referred to as a unit periodic structure. A structure having a periodic structure can be formed by repeatedly stacking the unit periodic structures in the Z-axis direction. The number of times the unit periodic structure is stacked is hereinafter referred to as a periodic structure stacking number.

The structure having the periodic structure formed as described above has a photonic crystal structure, and the waveguide structure 100 of the present embodiment has a photonic crystal structure. Wire 101 constituting the waveguide structure 100 is formed of a dielectric having a predetermined dielectric constant (a dielectric constant epsilon _b). Thereby, the waveguide structure 100 of this embodiment is comprised only with a dielectric material, without using a conductor.

A waveguide structure 100 having a photonic crystal structure as shown in FIG. 1 does not reflect and transmit electromagnetic waves in a predetermined frequency band. That is, if the length of one side of the cross section of the wire 101 is d,
f = c / (4 × _ne × d) (4)
For the electromagnetic wave in the vicinity of the frequency f given by (2), anything incident from any direction is reflected and not transmitted. This is an effect due to the waveguide structure 100 forming a photonic band gap. The bandwidth of the photonic band gap is about 10% of the frequency f. In equation (4), _ne represents the effective refractive index, and c represents the speed of light.

ε_ｒ＝（１−α）・ε_ａ＋α・ε_ｂ （６）
ここで、ε_ａは空気の比誘電率を示し、αは線材１０１の空間占有率を示している。図１に示すようなウッドパイル構造の本実施形態の導波路構造体１００では、空間占有率は０．５となる。 The effective refractive index _ne is given by the following equation.

ε _r = (1−α) · ε _a + α · ε _b (6)
Here, epsilon _a denotes the relative dielectric constant of air, alpha denotes the space occupancy of the wire 101. In the waveguide structure 100 of this embodiment having a woodpile structure as shown in FIG. 1, the space occupation ratio is 0.5.

  As described above, the waveguide structure 100 of the present embodiment formed in the photonic crystal structure can form a photonic band gap and shield electromagnetic waves in the vicinity of the frequency f. By forming the waveguide 110 as shown in FIG. 6, it is possible to confine electromagnetic waves in the vicinity of the frequency f. However, in order to realize a sufficiently high shielding effect against a predetermined electromagnetic wave, it is necessary to stack a predetermined number or more of unit periodic structures made of the wire 101.

  By using the waveguide structure 100 of the present embodiment, it is possible to form the waveguide 110 that does not use a conductor, and thus it is possible to provide the waveguide 110 with extremely small conductor loss. However, when the wall of the waveguide 110 is formed using the waveguide structure 100, a slight electric field energy penetrates into the waveguide structure 100 from the surface of the wall to about one to two unit periodic structures. And dielectric loss occurs. However, the magnitude of the dielectric loss generated in the waveguide structure 100 is sufficiently smaller than the conductor loss when the conductor wall is used.

  In the following, a description will be given of the magnitude of dielectric loss generated when an electromagnetic wave penetrates into the wall of the waveguide 110 formed by the waveguide structure 100 having a photonic crystal structure. FIG. 5 shows the electric field energy distribution of electromagnetic waves entering from the surface toward the inside when a plane wave is incident on the waveguide structure 100 of the present embodiment having the woodpile type photonic crystal structure shown in FIG.

ここで、ｃ₀は真空中の光速度(＝2.99792×１０^８[m/s])を表している。また、縦軸は電界エネルギー密度を表しており、導波路１１０の壁表面におけるエネルギー密度を１として規格化した値である。 In FIG. 5, the horizontal axis indicates the distance from the wall of the waveguide 110 formed by the waveguide structure 100 by the number L of the periodic structure stacks. The actual distance x [m] can be converted from the number L of the periodic structure layers by the following equation.

Here, c ₀ represents the speed of light in vacuum (= 2.99792 × 10 ⁸ [m / s]). The vertical axis represents the electric field energy density, which is a value normalized with the energy density at the wall surface of the waveguide 110 being 1.

FIG. 5 shows that the penetration length at which the energy density attenuates to 1 / e is when the number L of the periodic structure layers is about 1.6. For this reason, it is preferable that the number of periodic structure layers is 1.5 periods or more. Further, the actual distance x calculated from the number L of the periodic structure stacks becomes shorter as the effective refractive index _ne is larger from the equation (7). Therefore, when the waveguide structure 100 is manufactured using the dielectric wire 101 having a higher dielectric constant, the electromagnetic wave can be shielded with a smaller number L of the periodic structure layers, and the waveguide structure 100 is formed. The thickness of the wall of the waveguide 110 can be reduced.

  By the way, an actual dielectric has a dielectric loss depending on the dielectric loss tangent tan δ. Thereby, it is considered that the change in the electric field energy density with respect to the penetration depth is further attenuated as compared with the case shown in FIG. 5, and the penetration length that attenuates to 1 / e is shortened. FIG. 6 shows the relationship between the dielectric loss tangent tan δ and the penetration length that attenuates to 1 / e. In the figure, the horizontal axis represents the value of the dielectric loss tangent tan δ on a logarithmic scale, and the vertical axis represents the penetration length at which the energy density attenuates to 1 / e in terms of the same number L of periodic structure stacks as the horizontal axis of FIG. Represents.

In FIG. 6, when the dielectric loss tangent tan δ is sufficiently small 10 ⁻⁶ or less, the penetration length is the same as when there is no dielectric loss. On the other hand, when the dielectric loss tangent tan δ is larger than 10 ⁻⁵ , the penetration length gradually decreases as tan δ increases. This indicates that as the dielectric loss increases, the electric field energy that penetrates into the wall of the waveguide structure 100 is easily lost, so that electromagnetic waves cannot penetrate into the deep part of the wall.

A normal dielectric has a dielectric loss tangent tan δ in the range of about 10 ⁻⁴ to 10 ⁻² . Accordingly, when the waveguide 110 capable of sufficiently confining electromagnetic waves is formed using the waveguide structure 100 of the present embodiment, not only the dielectric constant of the dielectric used for the wire 101 but also the dielectric loss tangent tan δ. It is necessary to determine the wall thickness of the waveguide 110 in consideration of the size. From FIG. 6, it is possible to reduce the wall thickness of the waveguide 110 by forming the waveguide structure 100 using the wire 101 having a large dielectric loss tangent tan δ and forming the waveguide 110 using this. It becomes. Therefore, by using such a waveguide structure 100, it is possible to reduce the size of the waveguide 110.

  In general, it is preferable to use a dielectric having a small dielectric loss tangent tan δ for a waveguide such as a coaxial cable. However, in the waveguide structure 100 of this embodiment, a low-loss dielectric is always used. It has been shown above that the waveguide 110 can be miniaturized by using a dielectric having a large dielectric loss. Below, the magnitude | size of the dielectric loss of the waveguide 110 formed using the waveguide structure 100 is demonstrated.

As an example, glass epoxy having a high dielectric loss (tan δ = 0.02, ε _r = 4.5) is used for the wire 101, and the unit periodic structure of the woodpile structure shown in FIG. = 2) The waveguide 110 is formed by the formed waveguide structure 100 (thickness: about 6 mm). When a plane wave having an electric field intensity of 1 [V / m] is incident on the surface of the waveguide 110, the dielectric loss L _d = 6.6 × 10 ⁻⁵ [W] per unit area is obtained. This is about 1 / 100,000 of the conductor loss L _m = 7.8 [W] due to the skin effect when shielded by the conductor wall. As described above, even glass epoxy, which has been apt to be used in a millimeter-wave band waveguide because of its high loss, can be used for the waveguide structure 100 of the present embodiment. A sufficiently low waveguide 110 can be provided.

A waveguide structure 100 in which the unit periodical structure of the woodpile structure shown in FIG. 1 is formed in two layers (the number L = 2 of the periodic structure layers) using PTFE (polytetrafluoroethylene) or the like having a lower loss than glass epoxy. The case where the waveguide 110 is formed with a thickness of about 8 mm will be described. When a plane wave having an electric field intensity of 1 [V / m] is incident on the surface of the waveguide 110, the dielectric loss L _d = 5.2 × 10 ⁻⁷ [W] per unit area is obtained. Thus, when the waveguide structure 100 is formed using PTFE, the waveguide 110 with lower loss can be realized as compared with the case where glass epoxy is used.

  The waveguide structure 100 is produced using the wire 101 having a substantially square cross section formed of glass epoxy, and the measurement result of the transmission loss will be described below. A through hole having a cross section of 9 mm × 9 mm as shown in FIG. 2 is formed in the waveguide structure 100 and used for the waveguide 110. When an electromagnetic wave of 60 GHz was transmitted through the waveguide 110, the actually measured transmission loss was 0.2 [dB / m]. On the other hand, in the rectangular waveguide (for example, WRJ-620 manufactured by Furukawa C & B Co., Ltd.) conventionally used for transmission of electromagnetic waves of 60 GHz, the transmission loss is 2 [dB / m]. The transmission loss of the waveguide 110 is reduced to about 1/10 of the conventional one.

  In the above estimation of the transmission loss, the waveguide 110 of the present embodiment is reduced to about 1 / 100,000 as compared with the conventional waveguide. However, in the above actual measurement, the reduction is about 1/10. ing. This difference is considered to be due to the assembly accuracy of the photonic crystal structure when the waveguide structure 100 is manufactured. In the waveguide 110 formed by using the waveguide structure 100 of the present embodiment, the transmission loss can be reduced to about 1/10 that of the conventional waveguide even if the manufacturing accuracy is included, and the manufacturing accuracy is improved. As a result, transmission loss can be further reduced.

  A waveguide structure according to another embodiment of the present invention is shown in FIG. The waveguide structure 200 of the embodiment shown in FIG. 7A is manufactured using a cylindrical wire 201 having a circular cross section instead of the wire 101 having a square cross section. The method for manufacturing the waveguide structure 200 is similar to the method for manufacturing the waveguide structure 100 in that the wire structures 201 are arranged with an interval having the same width as the diameter of the cross section to form a layer structure per layer. Make it. Then, in the same manner as the method for manufacturing the waveguide structure 100, a unit periodic structure is manufactured by sequentially stacking layer structures per layer, and a predetermined number of periodic structure stacks are stacked. A waveguide structure 200 is produced. The waveguide structure 200 of the present embodiment uses the wire 201 having a circular cross section, but is not limited thereto, and can be manufactured using, for example, a wire having an elliptical cross section.

  The waveguide structure 210 according to the embodiment shown in FIG. 7B uses a flexible wire 211, which is knitted alternately while intersecting in two directions substantially orthogonal to each other, and further comprises two layers of the wire 211. The unit periodical structure of the braided structure is produced by adjusting the positions so that they do not overlap vertically. And the waveguide structure 210 is produced by laminating this unit periodic structure by a predetermined number of periodic structure laminations. As the flexible wire 211, for example, a material produced by kneading dielectric powder such as titanium dioxide and polyethylene can be used.

  The waveguide structure 200 or 210 manufactured as described above can realize an electromagnetic wave shielding effect by a photonic band gap in the vicinity of a frequency corresponding to each periodic structure. Therefore, by forming a waveguide using the waveguide structure 200 or 210 of the present embodiment, it is possible to provide a low-loss waveguide without conductor loss.

  FIG. 8 shows a waveguide structure according to still another embodiment of the present invention. The waveguide structure 300 of the present embodiment is a coaxial structure in which a woodpile structure is formed in a cylindrical shape. In order to form such a cylindrical photonic crystal structure, it is preferable to use a wire 301 made of a highly flexible dielectric. As such a wire 301, for example, titanium dioxide powder and polyethylene can be kneaded at a volume ratio of 1: 3 and formed into a prismatic shape having a cross-section of 0.25 mm × 0.25 mm. it can.

  A method for producing the waveguide structure 300 of the present embodiment having the coaxial structure will be described below with reference to FIGS. First, as shown in FIG. 9A, a wire 301 that is inclined to one side by about 45 degrees with respect to the longitudinal direction of the core wire 302 is wound along the core wire 302 so that the interval is equal to the width of the wire 301. Go. Thus, when the layer structure of the first layer is formed, the wire 301 is then wound again from above to form the layer structure of the second layer. In the second layer, the wire 301 is wound with an inclination of about 45 degrees on the side opposite to the first layer with respect to the longitudinal direction of the core wire 302. Thereby, the wire 301 is wound in the direction orthogonal to the 1st layer and the 2nd layer.

  Further, the layer structures of the third layer and the fourth layer are formed in the same manner as described above. However, the third layer wire 301 is wound so as to be positioned in the gap between the first layer wires 301, and the fourth layer wire 301 is wound in the gap between the second layer wires 301. Wrapped to position. Thus, a unit periodic structure having a cylindrical photonic crystal structure having a four-layer structure is formed. In the present embodiment, two of the unit periodic structures (periodic structure stacking number L is 2) are produced to form the inner wall portion 303.

  Next, as shown in FIG. 9B, the inner wall portion 303 produced above is inserted into the dielectric waveguide layer 304 in which the dielectric is formed in a tube shape. Thereafter, as shown in FIG. 9C, the wire 301 tilted about 45 degrees with respect to the longitudinal direction around the dielectric waveguide layer 304 is set so that the interval is equal to the width of the wire 301. I will wrap it around. Hereinafter, a layer structure from the first layer to the fourth layer is manufactured in the same manner as the manufacturing method of the inner wall portion 303, and this is used as a unit periodic structure. In the present embodiment, two unit periodic structures (periodic structure stacking number L is 2) are produced to form the outer wall portion 305.

The waveguide structure 300 of the present embodiment described above can be used for manufacturing a waveguide for transmitting an electromagnetic wave having a frequency of 60 GHz. As an example, a core wire 302 made of polyethylene having a diameter of 1 mm, an inner wall portion 303 (thickness 2 mm) having a periodic structure lamination number of 2, and a tubular dielectric waveguide layer made of PTFE having an inner diameter of 5 mm and an outer diameter of 7 mm. A waveguide structure 300 having a coaxial structure of 304 and an outer wall portion 305 (thickness 2 mm) having a periodic structure stacking number of 2 and an outer diameter of 11 mm can be manufactured. When this waveguide structure 300 is used, a waveguide having a relative dielectric constant of 47.8 and a dielectric loss tangent tan δ of 2 × 10 ⁻³ is formed. If an electromagnetic wave of 60 GHz is transmitted to this, the transmission loss becomes 0.4 [dB / m]. This is about 1/10 of the transmission loss 5 [dB / m] of the coaxial cable (trade name MWX261) conforming to MIL-C-17 / 151 used in the same frequency band, and a low-loss waveguide. Is realized.

  As described above, according to the present invention, it is possible to provide a waveguide structure capable of transmitting an electromagnetic wave in a high frequency region above the millimeter wave region with low loss. By forming the waveguide using such a low-loss waveguide structure, it is possible to realize energy saving and efficiency improvement of the transmission equipment.

  In addition, the description in this Embodiment shows an example of the waveguide structure and waveguide concerning this invention, and is not limited to this. The detailed structure and detailed operation of the waveguide structure and the waveguide in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

100, 200, 210, 300 Waveguide structure 10, 900 Coaxial cable 101, 201, 211, 301 Wire rod 110 Waveguide 302 Core wire 303 Inner wall 304 Dielectric waveguide layer 305 Outer wall 901 Central conductor 902 Dielectric layer 903 Core 904 Metal foil 905 External conductor layer 906 Conductor layer 907 Jacket

Claims (6)

A waveguide structure that transmits electromagnetic waves in a high frequency region above the millimeter wave region,
A first layer formed by arranging a wire made of a dielectric in parallel with an interval equal to the width of the wire;
A second layer formed by arranging the wires in parallel in a direction orthogonal to the wire forming the first layer at an interval equal to the width of the wires;
The wire is arranged in a direction parallel to the wire forming the first layer at an interval equal to the width of the wire, and at a position corresponding to a portion of the first layer where the wire is not disposed. A third layer disposed and formed;
The wires are arranged at intervals equal to the width of the wires in a direction parallel to the wires forming the second layer, and are arranged at positions corresponding to the intervals of the second layer. A waveguide structure comprising a periodic structure having a laminated structure including a fourth layer as a unit period of 1.5 periods or more. A waveguide structure that transmits electromagnetic waves in a high frequency region above the millimeter wave region,
A first layer of a braided structure in which two or more wires made of a dielectric are alternately braided in a direction orthogonal to each other;
A periodic structure having a unit structure of a laminated structure formed of the braided structure and the second layer disposed between the wires in which the wire does not overlap the wire forming the first layer is 1.5. A waveguide structure characterized by having a period or more. The waveguide structure according to claim 1 or 2, wherein the laminated structure is formed in a cylindrical shape on a surface of a linear conductor. The waveguide structure according to any one of claims 1 to 3, wherein the wire has a cross-sectional shape of one of a circle, an ellipse, and a polygon. A coaxial waveguide comprising a cylindrical inner wall portion and a cylindrical outer wall portion whose inner diameter is larger than the outer diameter of the inner wall portion,
4. The waveguide according to claim 3, wherein the inner wall portion and the outer wall portion are formed of the waveguide structure according to claim 3. A waveguide having a rectangular cross section and four wall surfaces surrounded by a plane parallel to the transmission direction,
A waveguide characterized in that the four wall surfaces are formed of the waveguide structure according to claim 1.

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