Impedance converter

Abstract

To provide an impedance converter capable of converting impedance through simple operation.SOLUTION: An impedance converter 1 comprises: a cavity 2 including an internal space 20 which is sealed in an electromagnetic manner; an input port 3 provided in the cavity 2 for inputting a radio wave to the internal space 20; an output port 4 provided in the cavity 2 for outputting a radio wave from the internal space 20; and an adjustment mechanism 5 including a metallic stab 6, which is positioned inside of the internal space 20, and adjusting the position of the stab 6 between the input port 3 and the output port 4 and an insertion length of the stab 6 into the internal space 20.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to an impedance converter. [Background technology]

[0002] Patent Document 1 discloses an automatic matching device that can accommodate changes in microwave frequency. The automatic matching device disclosed in Patent Document 1 is configured as part of a waveguide that connects a microwave power source and a load, and includes a directional coupler, three stubs, and a control unit. The three stubs function as impedance changing means that can change the reflection coefficient of the load-side reference point set at the load in the waveguide by adjusting the insertion length of each stub. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-32974 A Summary of the Invention [Problem to be solved by the invention]

[0004] The impedance changing means disclosed in Patent Document 1 changes the reflected impedance by changing the insertion length of three stubs. In Patent Document 1, there is no rule for the change in the actual impedance and the insertion length of the three stubs, so it is necessary to search for the conditions of the three stubs that will obtain the desired impedance by cut and try.

[0005] The present disclosure provides an impedance converter that enables impedance conversion with a simple operation. [Means for solving the problem]

[0006] An impedance converter according to one embodiment of the present disclosure comprises a cavity having an electromagnetically sealed internal space, an input port provided in the cavity for inputting radio waves into the internal space, an output port provided in the cavity for outputting radio waves from the internal space, and an adjustment mechanism having a metal stub located within the internal space and for adjusting the position of the stub between the input port and the output port and the insertion length of the stub into the internal space. Effect of the Invention

[0007] Aspects of the present disclosure allow for impedance transformation with simple manipulation. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a configuration example of an impedance converter according to an embodiment; [Diagram 2] FIG. 2 is another perspective view of the impedance converter of FIG. [Diagram 3] A plan view of the impedance converter of FIG. [Figure 4] Cross-sectional view of line AA in Figure 3 [Diagram 5] FIG. 2 is an exploded perspective view of the impedance converter of FIG. 1; [Figure 6] Cross-sectional view of the cavity of the impedance converter of FIG. [Figure 7] FIG. 2 is an exploded perspective view of an adjustment mechanism of the impedance converter of FIG. 1; [Figure 8] An enlarged view of the electrical connection area of ​​the impedance converter in Figure 1. [Figure 9] FIG. 2 is a plan view of a first example of the position of a stub in the impedance converter of FIG. 1; [Figure 10] Cross-sectional view of line BB in Figure 9 [Figure 11] FIG. 2 is a plan view of a second example of the position of a stub in the impedance converter of FIG. 1; [Figure 12] Cross section of line CC in Figure 11 [Figure 13] FIG. 2 is a cross-sectional view of a third example of the position of a stub in the impedance converter of FIG. 1; [Figure 14]FIG. 2 is a cross-sectional view of a fourth example of the position of a stub in the impedance converter of FIG. 1; [Figure 15] Smith chart showing a first example of impedance change caused by the impedance converter of FIG. 1 [Figure 16] Smith chart showing a second example of impedance change caused by the impedance converter of FIG. 1 [Figure 17] Smith chart showing a third example of impedance change caused by the impedance converter of FIG. 1 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the inventor(s) provide the attached drawings and the following explanation so that those skilled in the art can fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0010] Unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Each figure described in the following embodiments is a schematic diagram, and the ratio of the size and thickness of each component in each figure does not necessarily reflect the actual dimensional ratio. Furthermore, the dimensional ratio of each element is not limited to the ratio shown in the drawings.

[0011] [1. Embodiment] [1.1 Configuration] 1 to 5 show a configuration example of an impedance converter 1 according to the present embodiment. Fig. 1 is a perspective view (upper perspective view) of the impedance converter 1, and Fig. 2 is another perspective view (lower perspective view) of the impedance converter 1. Fig. 3 is a plan view of the impedance converter 1. Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. Fig. 5 is an exploded perspective view of the impedance converter 1.

[0012] As shown in FIGS. 1 to 5, the impedance converter 1 includes a cavity 2, an input port 3, an output port 4, and an adjustment mechanism 5. The cavity 2 has a cavity width 2a and an input port 3b.

[0013] The cavity 2 has an electromagnetically sealed internal space 20. The cavity 2 is made of metal. The material of the cavity 2 is, for example, aluminum, but is not particularly limited. The cavity 2 is rectangular parallelepiped. As shown in FIG. 4, the cavity 2 has a first wall 21 and a second wall 22 in a first direction (vertical direction in FIG. 4). The first wall 21 and the second wall 22 are rectangular plate-shaped with the same shape. The cavity 2 has a third wall 23 and a fourth wall 24 in a second direction (horizontal direction in FIG. 4) perpendicular to the first direction. The third wall 23 and the fourth wall 24 are rectangular plate-shaped with the same shape. As shown in FIG. 3, the cavity 2 has a fifth wall 25 and a sixth wall 26 in a third direction (vertical direction in FIG. 3) perpendicular to the first direction and the second direction, respectively. The fifth wall 25 and the sixth wall 26 are rectangular plate-shaped with the same shape. In this embodiment, the dimension of the cavity 2 in the second direction is the largest, the dimension of the cavity 2 in the third direction is the next largest, and the dimension of the cavity 2 in the first direction is the smallest.

[0014] The cavity 2 has, in the first wall portion 21, a mounting hole 27a for mounting the input port 3, a mounting hole 27b for mounting the output port 4, and an opening 28 for mounting the adjustment mechanism 5. The internal space 20 of the cavity 2 is surrounded by the first to sixth wall portions 21 to 26 and is electromagnetically sealed. Note that the mounting holes 27a, 27b and the opening 28 are formed in the cavity 2, and the internal space 20 is not spatially sealed, but the presence of the mounting holes 27a, 27b and the opening 28 can be ignored with respect to the electromagnetic sealing of the internal space 20 of the cavity 2.

[0015] As shown in FIG. 5, the first wall 21 of the cavity 2 has recesses 211a, 211b, a base 212, and a protrusion 213 on the first surface 21a opposite to the second wall 22. The recess 211a is located at the end of the first wall 21 on the third wall 23 side. The recess 211b is located at the end of the first wall 21 on the fourth wall 24 side. The recesses 211a, 211b are aligned in a straight line in the second direction of the cavity 2. The recesses 211a, 211b are, for example, rectangular. A mounting hole 27a is formed at the bottom of the recess 211a, and a mounting hole 27b is formed at the bottom of the recess 211b. The base 212 supports the adjustment mechanism 5. The base 212 is located at the end of the first wall 21 on the sixth wall 26 side. The base portion 212 has a rectangular plate shape extending in the second direction of the cavity 2. The protruding portion 213 is located between the mounting holes 27a, 27b in the first wall portion 21. The protruding portion 213 has a rectangular shape extending in the second direction of the cavity 2.

[0016] As shown in FIG. 4, the first wall 21 of the cavity 2 has a recess 214 on the second surface 21b on the second wall 22 side. FIG. 6 is a cross-sectional view of the cavity 2. More specifically, FIG. 6 is a cross-sectional view of the cavity 2 cut along the line XX in FIG. 4. As shown in FIG. 6, the recess 214 is between the mounting holes 27a and 27b on the second surface 21b of the first wall 21. The recess 214 extends in the second direction of the cavity 2. The recess 214 has an oval shape when viewed from the first direction. The recess 214 corresponds to the space inside the protrusion 213. An opening 28 is formed at the bottom of the recess 214. The opening 28 extends in the second direction of the cavity 2. The opening 28 is located between the mounting hole 27a for mounting the input port 3 and the mounting hole 27b for mounting the output port 4. Thus, the opening 28 is located in the first wall portion 21 between the input port 3 and the output port 4 .

[0017] The input port 3 is provided in the cavity 2 to input radio waves to the internal space 20. As shown in Figures 4 and 5, the input port 3 has an input antenna 31 and a connector 32. In this embodiment, the input port 3 receives a high-frequency signal from the outside at the connector 32, and inputs radio waves corresponding to the high-frequency signal from the input antenna 31 to the internal space 20.

[0018] The input antenna 31 is disposed in the internal space 20 of the cavity 2. The input antenna 31 is in the shape of a round bar. The material of the input antenna 31 is, for example, copper, but is not particularly limited. The input antenna 31 has a tip 31a and a body 31b. The diameter of the tip 31a is larger than the diameter of the body 31b. The input antenna 31 is positioned so that no discharge occurs between the tip 31a of the input antenna 31 and the cavity 2. In particular, the distances between the tip 31a of the input antenna 31 and the second wall 22, the third wall 23, the fifth wall 25, and the sixth wall 26 of the cavity 2 are set so that no discharge occurs between the tip 31a and each of the second wall 22, the third wall 23, the fifth wall 25, and the sixth wall 26.

[0019] The connector 32 is disposed outside the internal space 20 of the cavity 2, i.e., in the external space of the cavity 2. The connector 32 is used to connect the impedance converter 1 to an external device. In this embodiment, the connector 32 is a coaxial connector that can be connected to a coaxial cable. The connector 32 includes a rod-shaped internal conductor 32a, a cylindrical external conductor 32b that surrounds the internal conductor 32a, and an insulator 32c that is positioned between the internal conductor 32a and the external conductor 32b.

[0020] 4, the input port 3 is attached to the cavity 2 by utilizing the mounting hole 27a. The connector 32 is fixed in the recess 211a in the first surface 21a of the first wall 21 so that the input antenna 31 can be connected to the internal conductor 32a by the mounting hole 27a. The input antenna 31 is connected to the internal conductor 32a of the connector 32 at the body 31b.

[0021] The output port 4 is provided in the cavity 2 to output radio waves from the internal space 20. As shown in Figures 4 and 5, the output port 4 has an output antenna 41 and a connector 42. In this embodiment, the output port 4 receives radio waves from the internal space 20 at the output antenna 41 and outputs them in the form of a high-frequency signal via the connector 42.

[0022] The output antenna 41 is disposed in the internal space 20 of the cavity 2. The output antenna 41 is in the shape of a round bar. The material of the output antenna 41 is, for example, copper, but is not particularly limited to this. The output antenna 41 has a tip 41a and a body 41b. The diameter of the tip 41a is larger than the diameter of the body 41b. The output antenna 41 is positioned so that no discharge occurs between the tip 41a of the output antenna 41 and the cavity 2. In particular, the distances between the tip 41a of the output antenna 41 and the second wall 22, the fourth wall 24, the fifth wall 25, and the sixth wall 26 of the cavity 2 are set so that no discharge occurs between the tip 41a and each of the second wall 22, the fourth wall 24, the fifth wall 25, and the sixth wall 26.

[0023] The connector 42 is disposed outside the internal space 20 of the cavity 2, that is, in the external space of the cavity 2. The connector 42 is used to connect the impedance converter 1 to an external device. In the present embodiment, the connector 42 is a coaxial connector that can be connected to a coaxial cable. The connector 42 includes a rod-shaped inner conductor 42a, a cylindrical outer conductor 42b that surrounds the inner conductor 42a, and an insulator 42c that is positioned between the inner conductor 42a and the outer conductor 42b.

[0024] 4, the output port 4 is attached to the cavity 2 by utilizing the mounting hole 27b. The connector 42 is fixed in the recess 211b in the first surface 21a of the first wall 21 so that the output antenna 41 can be connected to the internal conductor 42a by the mounting hole 27b. The output antenna 41 is connected to the internal conductor 42a of the connector 42 at the body 41b.

[0025] In this embodiment, as shown in Figures 4 and 5, the shape of the input antenna 31 at the input port 3 and the shape of the output antenna 41 at the output port 4 are the same. More specifically, the tip 31a of the input antenna 31 and the tip 41a of the output antenna 41 have the same diameter and length. The body 31b of the input antenna 31 and the body 41b of the output antenna 41 have the same diameter and length.

[0026] In this embodiment, as shown in Fig. 3, the input port 3 and the output port 4 are aligned in the second direction of the cavity 2 (left-right direction in Fig. 3) when viewed from the first direction of the cavity 2. A straight line L1 passing through the input port 3 and the output port 4 corresponds to a center line in the third direction of the cavity 2 (up-down direction in Fig. 3) when viewed from the first direction of the cavity 2. In Fig. 3, the cavity 2 is symmetrical with respect to the straight line L1 passing through the input port 3 and the output port 4 when viewed from the first direction.

[0027] In this embodiment, the input port 3 is closer to the third wall portion 23 than the output port 4. In other words, the output port 4 is closer to the fourth wall portion 24 than the input port 3. As shown in Fig. 4, a distance D11 between the input port 3 and the third wall portion 23 and a distance D12 between the output port 4 and the fourth wall portion 24 are equal to each other.

[0028] In the impedance converter 1, power is input by a high-frequency signal to the connector 32 of the input port 3. The power input to the input port 3 causes the input antenna 31 to radiate radio waves into the internal space 20 of the cavity 2. The output port 4 receives the radio waves via the output antenna 41, and outputs a high-frequency signal corresponding to the radio waves from the connector 42.

[0029] The adjustment mechanism 5 adjusts the impedance between the input port 3 and the output port 4. In this embodiment, the adjustment mechanism 5 has a metal stub 6. Depending on how the stub 6 is arranged in the internal space 20 of the cavity 2, the influence on the transmission of radio waves from the input port 3 to the output port 4 differs. That is, the impedance between the input port 3 and the output port 4 can be adjusted by the stub 6. The adjustment mechanism 5 adjusts the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20. In particular, the adjustment mechanism 5 individually adjusts the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20. The insertion length is the effective length of the portion of the stub 6 that is in the internal space 20. The effective length can be the length of the portion that affects the impedance. In this embodiment, the insertion length corresponds to the distance between the tip of the stub 6 in the first direction and the second surface 21b of the first wall portion 21. When the tip of the stub 6 does not protrude from the second surface 21b, the insertion length is set to 0.

[0030] 7 is an exploded perspective view of the adjustment mechanism 5. The adjustment mechanism 5 includes a stub 6, a position adjustment mechanism 71, an insertion length adjustment mechanism 72, a support 73, and an electrical connection portion 8.

[0031] The stub 6 is made of metal. The material of the stub 6 is aluminum, but is not limited to this. The stub 6 in FIG. 7 is rod-shaped. The stub 6 has a tip 6a, a rear end 6b, and an intermediate portion 6c between the tip 6a and the rear end 6b. The tip 6a is disk-shaped. However, the corners of the tip 6a are rounded. This can reduce the electric field intensity at the corners of the tip 6a, and can reduce discharge between the tip 6a and the cavity 2. The rear end 6b and the intermediate portion 6c are flat. The width of the intermediate portion 6c is smaller than the width of the rear end 6b. The dimension of the tip 6a of the stub 6 in the third direction is larger than the dimension of the opening 28 in the third direction, and the tip 6a cannot pass through the opening 28. The dimension of the rear end 6b and the intermediate portion 6c of the stub 6 in the third direction is smaller than the dimension of the opening 28 in the third direction, and the tip 6a can pass through the opening 28.

[0032] 4, the stub 6 penetrates the opening 28 such that the tip end 6a of the stub 6 is located inside the internal space 20 and the rear end 6b of the stub 6 is located outside the internal space 20. The tip end 6a of the stub 6 can be accommodated in the recess 214 of the cavity 2. Particularly in this embodiment, the recess 214 is sized to accommodate the tip end 6a of the stub 6 such that the tip end 6a of the stub 6 does not protrude from the recess 214 towards the second wall 22 in the first direction.

[0033] The position adjustment mechanism 71 holds the stub 6 movable along the second direction within the opening 28. The position adjustment mechanism 71 has a movable part 711 and a fixed part 712. In the position adjustment mechanism 71, the stub 6 is attached to the movable part 711. The fixed part 712 is fixed to the cavity 2 in the second direction, and holds the movable part 711 movable in the second direction.

[0034] The fixed part 712 has a base 712a, a rail 712b, and a screw 712c. The base 712a is a rectangular plate. The base 712a is attached to the platform 212 of the cavity 2. The rail 712b is used to connect the movable part 711 to the fixed part 712. The rail 712b extends in the second direction. The rail 712b is attached to the base 712a. The rail 712b has a shape that becomes wider toward the tip. This allows the movable part 711 and the fixed part 712 to be connected so as not to come off in the first direction. The screw 712c moves the movable part 711 in the second direction relative to the fixed part 712. The screw 712c is rotatable around a rotation axis parallel to the second direction. The movable part 711 is a rectangular parallelepiped.

[0035] The movable part 711 has a rail groove 711a corresponding to the rail 712b of the fixed part 712. A thread groove that meshes with the thread groove of the screw 712c is formed in the rail groove 711a. The movable part 711 has an attachment surface 711b on the opposite side to the rail groove 711a. In this embodiment, the stub 6 is indirectly attached to the attachment surface 711b via the support 73 and the insertion length adjustment mechanism 72.

[0036] In the position adjustment mechanism 71, by rotating the screw 712c of the fixed part 712, the rotational motion of the screw 712c is converted into linear motion in the second direction, and the movable part 711 moves along the second direction.

[0037] The insertion length adjustment mechanism 72 holds the stub 6 movably along the first direction. The insertion length adjustment mechanism 72 has a movable part 721 and a fixed part 722. In the insertion length adjustment mechanism 72, the stub 6 is attached to the movable part 721. The fixed part 722 is fixed to the cavity 2 in the first direction and holds the movable part 721 movably in the first direction.

[0038] The fixed part 722 has a base 722a, a rail groove 722b, and a screw 722c. The base 722a is a rectangular plate. The base 722a is attached to the mounting surface 711b of the movable part 711 of the position adjustment mechanism 71 via the support 73. The rail groove 722b is used to couple the movable part 721 to the fixed part 722. The rail groove 722b extends in the first direction. The rail groove 722b is formed on one surface of the base 722a. The screw 722c moves the movable part 721 in the first direction relative to the fixed part 722. The screw 722c is rotatable around a rotation axis parallel to the second direction. The movable part 721 is a rectangular parallelepiped.

[0039] Movable part 721 has rail 721a that corresponds to rail groove 722b of fixed part 722. Rail 721a has a shape that increases in width toward the tip. This allows movable part 721 and fixed part 722 to be coupled together so as not to come apart in the third direction.

[0040] In the insertion length adjustment mechanism 72, by rotating the screw 722c of the fixed portion 722, the rotational motion of the screw 722c is converted into linear motion in a first direction, and the movable portion 721 moves along the first direction.

[0041] The support 73 is a member for attaching the insertion length adjustment mechanism 72 and the electrical connection portion 8 to the movable portion 711 of the position adjustment mechanism 71. The support 73 has a fixed portion 73a, a first support 73b, a second support 73c, and a pair of connecting portions 73d. The fixed portion 73a is fixed to the mounting surface 711b of the movable portion 711 of the position adjustment mechanism 71. The first support 73b is a flat plate extending parallel to the first direction from the fixed portion 73a. The fixed portion 722 of the insertion length adjustment mechanism 72 is attached to the first support 73b. The second support 73c is fixed to the fixed portion 73a by the pair of connecting portions 73d so as to face the protrusion 213 of the cavity 2 in the first direction. The fixed portion 73a has a through hole 731 facing the opening 28 of the cavity 2 in the first direction. The through hole 731 is smaller than the front end 6a and rear end 6b but larger than the intermediate portion 6c of the stub 6. A recess 732 for accommodating the electrical connection portion 8 is formed in the surface of the second support 73c facing the cavity 2 (see FIG. 8).

[0042] The electrical connection portion 8 electrically connects the stub 6 to the cavity 2. Since the stub 6 is disposed to penetrate the opening 28, it can function as an antenna that allows a portion of the radio waves from the input antenna 31 to escape from the internal space 20 of the cavity 2 to the outside. By electrically connecting the stub 6 to the cavity 2, the electrical connection portion 8 prevents the stub 6 from functioning as such an antenna, thereby making it possible to reduce power leakage through the stub 6.

[0043] 8 is an enlarged view of the periphery of the electrical connection portion 8. As shown in FIGS. 7 and 8, the electrical connection portion 8 has a pair of first conductive members 81, a second conductive member 82, and a pair of biasing members 83.

[0044] Each of the pair of first conductive members 81 is located outside the internal space 20 of the cavity 2 and is in elastic contact with the stub 6 in the third direction. In this embodiment, the pair of first conductive members 81 are located on both sides of the stub 6 in the third direction (the left-right direction in FIG. 8 ) and sandwich the stub 6 therebetween. Each of the first conductive members 81 is a leaf spring. Since the first conductive members 81 are in elastic contact with the stub 6, the stub 6 can be moved in the first direction by the insertion length adjustment mechanism 72 with the first conductive members 81 in stable electrical contact with the stub 6.

[0045] The second conductive member 82 is located outside the internal space 20 of the cavity 2, and electrically connects the first conductive member 81 to the peripheral portion of the opening 28 of the cavity 2. The second conductive member 82 is rectangular box-shaped. The second conductive member 82 has a through hole 82a through which the stub 6 passes. The second conductive member 82 accommodates the pair of first conductive members 81, 81 so as to be located on both sides of the through hole 82a in the third direction. As a result, the second conductive member 82 holds the pair of first conductive members 81 so as to be in elastic contact with the stub 6. The second conductive member 82 contacts the protrusion 213. As a result, the pair of first conductive members 81 are electrically connected to the peripheral portion of the opening 28 of the cavity 2 via the second conductive member 82.

[0046] The pair of biasing members 83 bias the second conductive member 82 toward the cavity 2 so that the second conductive member 82 elastically contacts the protrusion 213 of the cavity 2. The pair of biasing members 83 are, for example, coil springs. Since the biasing members 83 cause the second conductive member 82 to elastically contact the protrusion 213 of the cavity 2, the stub 6 can be moved in the second direction by the position adjustment mechanism 71 with the second conductive member 82 in stable electrical contact with the cavity 2.

[0047] Thus, the electrical connection 8 electrically connects the stub 6 to the cavity 2. This makes it possible to reduce power leakage through the stub 6.

[0048] In the adjustment mechanism 5 described above, the fixed part 712 of the position adjustment mechanism 71 is directly fixed to the cavity 2. The fixed part 722 of the insertion length adjustment mechanism 72 is fixed to the movable part 711 of the position adjustment mechanism 71 via the support 73. The stub 6 is fixed to the movable part 721 of the insertion length adjustment mechanism 72. This allows the position adjustment mechanism 71 to move the stub 6, the insertion length adjustment mechanism 72, and the support 73 together with the movable part 711 in the second direction. The insertion length adjustment mechanism 72 allows the stub 6 to move together with the movable part 721 in the first direction.

[0049] [1.2 Operation] Next, the operation of the impedance converter 1 will be described.

[0050] In the impedance converter 1, the impedance is adjusted using an adjustment mechanism 5. With the adjustment mechanism 5, the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20 can be adjusted individually.

[0051] The position of the stub 6 between the input port 3 and the output port 4 is adjusted by a position adjustment mechanism 71. In the position adjustment mechanism 71, by rotating the screw 712c of the fixed part 712, the rotational motion of the screw 712c is converted into linear motion in a second direction, and the movable part 711 moves along the second direction. Depending on the direction of rotation of the screw 712c, the stub 6 can be moved toward the input port 3 or the output port 4.

[0052] Fig. 9 is a plan view of a first example of the position of the stub 6 in the impedance converter 1. Fig. 10 is a cross-sectional view of line BB in Fig. 9. In the first example, the stub 6 is at the end of the opening 28 on the input port 3 side in the second direction. This is the position closest to the input port 3 within the movable range of the stub 6 in the second direction.

[0053] Fig. 11 is a plan view of a second example of the position of the stub 6 in the impedance converter 1. Fig. 12 is a cross-sectional view of line CC in Fig. 11. In the second example, the stub 6 is at the end of the opening 28 on the output port 4 side in the second direction. This is the position closest to the output port 4 within the movable range of the stub 6 in the second direction.

[0054] The position adjustment mechanism 71 allows the stub 6 to be moved between a position closest to the input port 3 (see Figures 9 and 10) and a position closest to the output port 4 (see Figures 11 and 12) within the movable range of the stub 6 in the second direction.

[0055] The insertion length of the stub 6 into the internal space 20 is adjusted by the insertion length adjustment mechanism 72. In the insertion length adjustment mechanism 72, by rotating the screw 722c of the fixed part 722, the rotational motion of the screw 722c is converted into linear motion in a first direction, and the movable part 721 moves along the first direction. Depending on the direction of rotation of the screw 722c, the stub 6 can be moved in a direction entering the internal space 20 (a direction in which the insertion length increases) or in a direction exiting the internal space 20 (a direction in which the insertion length decreases).

[0056] 13 is a cross-sectional view of a third example of the position of the stub 6 in the impedance converter 1. The third example is a position where the insertion length is maximum within the movable range of the stub 6 in the first direction. In the third example, the rear end 6b of the stub 6 abuts on the edge of the through hole 731 of the second support 73c of the support 73, and the movement of the stub 6 in the direction into the internal space 20 is restricted.

[0057] FIG. 14 is a cross-sectional view of a fourth example of the position of the stub 6 in the impedance converter 1. The fourth example is a position where the insertion length is the smallest in the movable range of the stub 6 in the first direction. In the fourth example, the tip 6a of the stub 6 is accommodated in the recess 214 of the cavity 2. The tip 6a of the stub 6 does not protrude from the recess 214 toward the second wall 22 in the first direction. This is equivalent to the case where the insertion length of the stub 6 into the internal space 20 is substantially 0. In other words, the stub 6 can be hidden from the input port 3 and the output port 4, and the impedance between the input port 3 and the output port 4 can be set to a value equivalent to that in the absence of the stub 6. Since the opening 28 is smaller than the tip 6a of the stub 6 in the third direction, the tip 6a of the stub 6 hits the bottom of the recess 214, restricting the movement of the stub 6 in the direction out of the internal space 20.

[0058] The insertion length adjustment mechanism 72 allows the stub 6 to be moved between a position where the insertion length is longest (see FIG. 3) and a position where the insertion length is shortest (see FIG. 14) within the movable range of the stub 6 in the first direction.

[0059] [1.3 Evaluation] Next, the S-parameters were evaluated using a network analyzer to evaluate the change in impedance of the impedance converter 1. In this evaluation, a 50 Ω termination resistor was connected to the output port 4. In evaluating the S-parameters, the reflection coefficient (S11) of the input port 3 was used.

[0060] FIG. 15 is a Smith chart showing a first example of the change in impedance caused by the impedance converter 1. In the first example, the insertion length of the stub 6 into the internal space 20 was changed. That is, the stub 6 was moved in a first direction by the insertion length adjustment mechanism 72. As the insertion length of the stub 6 into the internal space 20 increased, the impedance changed as shown by the arrow A1. The impedance includes a resistance component and a reactance component. It can be seen from FIG. 15 that the change in the insertion length of the stub 6 has a large effect on the resistance component of the impedance.

[0061] FIG. 16 is a Smith chart showing a second example of the change in impedance caused by the impedance converter 1. In the second example, the position of the stub 6 between the input port 3 and the output port 4 was changed. That is, the stub 6 was moved in the second direction by the position adjustment mechanism 71. When the stub 6 was moved from the input port 3 side to the output port 4 side within the opening 28, the impedance changed as shown by the arrow A2. The impedance includes a resistance component and a reactance component. It can be seen from FIG. 16 that the change in the position of the stub 6 between the input port 3 and the output port 4 has a large effect on the reactance component of the impedance.

[0062] Fig. 17 is a Smith chart showing a third example of the change in impedance caused by the impedance converter 1. From the results of Fig. 15 and Fig. 16, the position of the stub 6 between the input port 3 and the output port 4 was changed for each insertion length of the stub 6 into the internal space 20. Arrows A31, A32, A33, A34, and A35 in Fig. 17 indicate the change in impedance due to the change in the position of the stub 6 between the input port 3 and the output port 4 at the corresponding insertion length. The insertion length of the arrow A31 is the smallest, followed by the arrows A32, A33, A34, and A35 in that order.

[0063] 15 to 17, it can be seen that the impedance can be adjusted by the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20. In particular, the reactance component of the impedance can be adjusted by the position of the stub 6 between the input port 3 and the output port 4, and the resistance component of the impedance can be adjusted by the insertion length of the stub 6 into the internal space 20. In other words, the resistance component and the reactance component of the impedance can be adjusted individually by the stub 6.

[0064] As a result of trying out various designs for the impedance converter 1, it was confirmed that it is possible to achieve a change in reflectivity of 0 to 98% and a change in reflection phase of 0 to 360° in the frequency range of 2400 MHz to 2500 MHz, and that the loss can be suppressed to 0.4% to 1%. Here, the reflectivity is related to the resistance component of the impedance, and the reflection phase is related to the reactance component of the impedance.

[0065] In the impedance converter 1 described above, the position of the stub 6 between the input port 3 and the output port 4 can adjust the reactance component of the impedance (reflection phase), and the insertion length of the stub 6 into the internal space 20 can adjust the resistive component of the impedance (reflection rate). Compared to Patent Document 1, there is no need to repeatedly perform cut-and-try for changes in the three stubs and reflected impedance, and the impedance can be adjusted by utilizing the correlation between the stub 6 and the resistive component (reflection rate) and reactance component (reflection phase) of the impedance, making the operation for adjusting the impedance easier. Furthermore, the impedance converter 1 can be made smaller than a conventionally known EH tuner that requires two plungers perpendicular to the waveguide direction.

[0066] [1.4 Effects, etc.] The impedance converter 1 described above comprises a cavity 2 having an electromagnetically sealed internal space 20, an input port 3 provided in the cavity 2 for inputting radio waves into the internal space 20, an output port 4 provided in the cavity 2 for outputting radio waves from the internal space 20, and an adjustment mechanism 5 having a metal stub 6 located within the internal space 20 and for adjusting the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20. This configuration enables impedance conversion with a simple operation.

[0067] In the impedance converter 1, the adjustment mechanism 5 individually adjusts the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20. This configuration can improve the degree of freedom in impedance conversion.

[0068] In the impedance converter 1, the cavity 2 has a first wall 21 and a second wall 22 in a first direction. The input port 3 is located in the first wall 21 or the second wall 22. The output port 4 is located in the first wall 21 or the second wall 22. When viewed from the first direction, the input port 3 and the output port 4 are aligned in a second direction perpendicular to the first direction. This configuration can reduce power loss.

[0069] In the impedance converter 1, the cavity 2 has an opening 28 in the first wall portion 21 between the input port 3 and the output port 4. The stub 6 passes through the opening 28 so that the tip end 6a of the stub 6 is located inside the internal space 20 and the rear end 6b of the stub 6 is located outside the internal space 20. This configuration enables impedance conversion with a simple operation.

[0070] In the impedance converter 1, the opening 28 extends in the second direction. The adjustment mechanism 5 includes a position adjustment mechanism 71 that holds the stub 6 within the opening 28 so that it is movable along the second direction. The position adjustment mechanism 71 has a movable part 711 to which the stub 6 is attached, and a fixed part 712 that is fixed to the cavity 2 in the second direction and holds the movable part 711 of the position adjustment mechanism 71 so that it is movable in the second direction. This configuration enables impedance conversion with a simple operation.

[0071] In the impedance converter 1, the adjustment mechanism 5 includes an insertion length adjustment mechanism 72 that holds the stub 6 movably along the first direction. The insertion length adjustment mechanism 72 has a movable part 721 to which the stub 6 is attached, and a fixed part 722 that is fixed to the cavity 2 in the first direction and holds the movable part 721 of the insertion length adjustment mechanism 72 movably in the first direction. This configuration enables impedance conversion with a simple operation.

[0072] In the impedance converter 1, the cavity 2 has a recess 214 on the second surface 21b of the first wall 21 facing the second wall 22. The opening 28 is at the bottom of the recess 214. The recess 214 has a size capable of accommodating the tip 6a of the stub 6 such that the tip 6a does not protrude from the recess 214 towards the second wall 22 in the first direction. This configuration makes it possible to hide the stub 6 from the input port 3 and the output port 4, and to set the impedance between the input port 3 and the output port 4 to a value equivalent to that in the absence of the stub 6.

[0073] In the impedance converter 1, the adjustment mechanism 5 further includes an electrical connection 8 that electrically connects the stub 6 to the cavity 2. This configuration can reduce power leakage through the stub 6.

[0074] In the impedance converter 1, the electrical connection portion 8 includes a first conductive member 81 located outside the internal space 20 of the cavity 2 and elastically contacting the stub 6 in a third direction perpendicular to the first direction and the second direction, and a second conductive member 82 located outside the internal space 20 of the cavity 2 and electrically connecting the first conductive member 81 to a peripheral portion of the opening 28 of the cavity 2. This configuration can reduce power leakage through the stub 6.

[0075] In the impedance converter 1, when viewed from the first direction, the cavity 2 is symmetrical with respect to a line passing through the input port 3 and the output port 4. This configuration can further reduce power loss.

[0076] In the impedance converter 1, the cavity 2 has a third wall 23 and a fourth wall 24 in the second direction. The input port 3 is closer to the third wall 23 than the output port 4. A distance D11 between the input port 3 and the third wall 23 and a distance D12 between the output port 4 and the fourth wall 24 are equal to each other. This configuration can further reduce power loss.

[0077] In the impedance converter 1, the input port 3 and the output port 4 are on the first wall 21. This configuration can further reduce power losses.

[0078] In the impedance converter 1, the input port 3 has an input antenna 31 located within the interior space 20. The output port 4 has an output antenna 41 located within the interior space 20. This configuration allows for the transmission of high frequency signals.

[0079] In the impedance converter 1, the input antenna 31 and the output antenna 41 have the same shape. This configuration can further reduce power loss.

[0080] In the impedance converter 1, the input antenna 31 is positioned so that no discharge occurs between the tip 31a of the input antenna 31 and the cavity 2. The output antenna 41 is positioned so that no discharge occurs between the tip 41a of the output antenna 41 and the cavity 2. This configuration can reduce the influence of discharge between the input antenna 31 and the cavity 2 and between the output antenna 41 and the cavity 2.

[0081] [2. Modifications] The embodiments of the present disclosure are not limited to the above-mentioned embodiments. The above-mentioned embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Below, modified examples of the above-mentioned embodiments are listed. The modified examples described below can be applied in appropriate combination.

[0082] In one modified example, the shape of the cavity 2 is not particularly limited. The dimensions of the cavity 2 in the first direction, the second direction, and the third direction are appropriately set in consideration of the arrangement of the input port and the output port, the frequency of the high-frequency signal input to the input port, and the like. All of the dimensions of the cavity 2 in the first direction, the second direction, and the third direction relate to the efficiency (power loss) and frequency characteristics. When determining the dimensions of the cavity 2, the dimension to be fixed and the dimension to be optimized may be changed hierarchically, while fixing the other dimensions and optimizing one dimension. For example, when determining the dimensions of the cavity 2 in the first direction, the second direction, and the third direction, respectively, the dimensions in the first direction and the second direction are first fixed to arbitrary values, and the dimension in the third direction is optimized. Next, the dimension in the first direction is not changed, and the dimension in the second direction is changed, and the dimension in the third direction is optimized. In this way, an optimal combination of the dimensions in the second direction and the third direction is searched for with respect to the current dimension in the first direction. The dimension in the first direction is changed, and the optimal combination of the dimensions in the second direction and the third direction is searched for. In this way, the optimum combination of dimensions in the first direction, second direction, and third direction is finally searched for.

[0083] In one modified example, the cavity 2 is not particularly limited to a rectangular parallelepiped shape. The cavity 2 may be a circular or polygonal box shape. As described above, the dimensions of the cavity 2 may be appropriately set in consideration of the arrangement of the input port and the output port, the frequency of the high-frequency signal input to the input port, and the like.

[0084] In one modified example, the shapes of the input antenna 31 of the input port 3 and the output antenna 41 of the output port 4 are not particularly limited. In one modified example, the shapes of the connectors 32, 42 of the input port 3 and the output port 4 are not particularly limited. The input port 3 may be a waveguide input section configured with an opening provided in the cavity 2 to input radio waves into the internal space 20. In this case, the input port 3 may input the radio waves directly into the internal space 20. The output port 4 may be a waveguide output section configured with an opening provided in the cavity 2 to output the radio waves from the internal space 20. In this case, the output port 4 may output the radio waves directly from the internal space 20.

[0085] In one modification, the configuration of the cavity 2, the input port 3, and the output port 4, for example, the relative shapes and positional relationships, may be different from those of the embodiment. The input port 3 and the output port 4 do not necessarily have to be in the first wall portion 21. The input port 3 may be in the first wall portion 21 or the second wall portion 22, and the output port 4 may be in the first wall portion 21 or the second wall portion 22. When viewed from the first direction, the input port 3 and the output port 4 do not necessarily have to be aligned in the second direction. When viewed from the first direction, the cavity 2 does not have to be line-symmetrical with respect to a straight line passing through the input port 3 and the output port 4. The distance D11 between the input port 3 and the third wall portion 23 and the distance D12 between the output port 4 and the fourth wall portion 24 do not have to be equal to each other.

[0086] In one modified example, the adjustment mechanism 5 is only required to be able to adjust the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20, and is not necessarily required to be able to individually adjust the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20. In other words, the adjustment mechanism 5 may be configured to simultaneously adjust the position of the stub 6 between the input port 3 and the output port 4 and the insertion length of the stub 6 into the internal space 20.

[0087] In one modified example, the fixed portion 722 of the insertion length adjustment mechanism 72 may be fixed to the cavity 2 , and the position adjustment mechanism 71 may be fixed to the movable portion 721 of the insertion length adjustment mechanism 72 .

[0088] In one modified example, the configurations of the position adjustment mechanism 71 and the insertion length adjustment mechanism 72 may be modified as appropriate, as long as the stub 6 can be moved in a desired direction using a conventionally known configuration.

[0089] In one variant, the adjustable range of the position of the stub 6 between the input port 3 and the output port 4 and the adjustable range of the insertion length of the stub 6 into the internal space 20 may be set appropriately depending on the performance required of the impedance converter 1.

[0090] In one variant, the cavity 2 may not have the recess 214. That is, the stub 6 may not be able to be placed in a position where it can be hidden relative to the input port 3 and the output port 4.

[0091] In one variant, the adjustment mechanism 5 may not have the electrical connection 8. As an example, the electrical connection 8 may be omitted, for example, in cases where the effect of power leakage through the stub 6 is negligible.

[0092] [3. Aspects] As is apparent from the above-described embodiment and modified examples, the present disclosure includes the following aspects. In the following, reference symbols are given in parentheses only to clarify the correspondence with the embodiment.

[0093] The first aspect is an impedance converter (1) comprising a cavity (2) having an electromagnetically sealed internal space (20), an input port (3) provided in the cavity (2) for inputting radio waves into the internal space (20), an output port (4) provided in the cavity (2) for outputting radio waves from the internal space (20), and an adjustment mechanism (5) having a metal stub (6) located within the internal space (20) and adjusting the position of the stub (6) between the input port (3) and the output port (4) and the insertion length of the stub (6) into the internal space (20). This aspect enables impedance conversion with a simple operation.

[0094] The second aspect is an impedance converter (1) based on the first aspect. In the second aspect, the adjustment mechanism (5) individually adjusts the position of the stub (6) between the input port (3) and the output port (4) and the insertion length of the stub (6) into the internal space (20). This aspect can improve the degree of freedom of impedance conversion.

[0095] A third aspect is an impedance converter (1) based on the first or second aspect. In the third aspect, the cavity (2) has a first wall (21) and a second wall (22) in a first direction. The input port (3) is in the first wall (21) or the second wall (22). The output port (4) is in the first wall (21) or the second wall (22). When viewed from the first direction, the input port (3) and the output port (4) are aligned in a second direction perpendicular to the first direction. This aspect can reduce power loss.

[0096] A fourth aspect is an impedance converter (1) based on the third aspect. In the fourth aspect, the cavity (2) has an opening (28) in the first wall portion (21) between the input port (3) and the output port (4). The stub (6) passes through the opening (28) such that the front end (6a) of the stub (6) is located inside the internal space (20) and the rear end (6b) of the stub (6) is located outside the internal space (20). This aspect enables impedance conversion with a simple operation.

[0097] A fifth aspect is an impedance converter (1) based on the fourth aspect. In the fifth aspect, the opening (28) extends in the second direction. The adjustment mechanism (5) includes a position adjustment mechanism (71) that holds the stub (6) movably along the second direction within the opening (28). The position adjustment mechanism (71) has a movable part (711) to which the stub (6) is attached, and a fixed part (712) that is fixed to the cavity (2) in the second direction and holds the movable part (711) of the position adjustment mechanism (71) movably in the second direction. This aspect enables impedance conversion with a simple operation.

[0098] A sixth aspect is an impedance converter (1) based on the fourth or fifth aspect. In the sixth aspect, the adjustment mechanism (5) includes an insertion length adjustment mechanism (72) that holds the stub (6) movably along the first direction. The insertion length adjustment mechanism (72) has a movable part (721) to which the stub (6) is attached, and a fixed part (722) that is fixed to the cavity (2) in the first direction and holds the movable part (721) of the insertion length adjustment mechanism (72) movably in the first direction. This aspect enables impedance conversion with a simple operation.

[0099] The seventh aspect is the impedance converter (1) based on the sixth aspect. In the seventh aspect, the cavity (2) has a recess (214) on a surface (second surface 21b) of the first wall portion (21) facing the second wall portion (22). The opening (28) is at the bottom of the recess (214). The recess (214) has a size capable of accommodating the tip portion (6a) of the stub (6) such that the tip portion (6a) of the stub (6) does not protrude from the recess (214) toward the second wall portion (22) in the first direction. In this aspect, the stub (6) can be hidden from the input port (3) and the output port (4), and the impedance between the input port (3) and the output port (4) can be set to a value equivalent to that in the absence of the stub (6).

[0100] An eighth aspect is an impedance converter (1) based on any one of the fourth to seventh aspects. In the eighth aspect, the adjustment mechanism (5) further includes an electrical connection part (8) that electrically connects the stub (6) to the cavity (2). This aspect can reduce power leakage through the stub (6).

[0101] A ninth aspect is an impedance converter (1) based on the eighth aspect. In the ninth aspect, the electrical connection portion (8) includes a first conductive member (81) located outside the internal space (20) of the cavity (2) and elastically contacting the stub (6) in a third direction perpendicular to the first direction and the second direction, and a second conductive member (82) located outside the internal space (20) of the cavity (2) and electrically connecting the first conductive member (81) to a peripheral portion of the opening (28) of the cavity (2). This aspect can reduce power leakage through the stub (6).

[0102] A tenth aspect is an impedance converter (1) based on any one of the fourth to ninth aspects. In the tenth aspect, when viewed from the first direction, the cavity (2) is symmetrical with respect to a line passing through the input port (3) and the output port (4). This aspect can further reduce power loss.

[0103] An eleventh aspect is an impedance converter (1) based on any one of the fourth to tenth aspects. In the eleventh aspect, the cavity (2) has a third wall portion (23) and a fourth wall portion (24) in the second direction. The input port (3) is closer to the third wall portion (23) than the output port (4). A distance (D11) between the input port (3) and the third wall portion (23) and a distance (D12) between the output port (4) and the fourth wall portion (24) are equal to each other. This aspect can further reduce power loss.

[0104] A twelfth aspect is an impedance converter (1) based on any one of the fourth to eleventh aspects. In the twelfth aspect, the input port (3) and the output port (4) are located in the first wall portion (21). This aspect can further reduce power loss.

[0105] A thirteenth aspect is an impedance converter (1) based on any one of the first to twelfth aspects. In the thirteenth aspect, the input port (3) has an input antenna (31) located in the internal space (20). The output port (4) has an output antenna (41) located in the internal space (20). This aspect enables transmission of high-frequency signals.

[0106] A fourteenth aspect is the impedance converter (1) based on the thirteenth aspect. In the fourteenth aspect, the input antenna (31) and the output antenna (41) have the same shape. This aspect can further reduce power loss.

[0107] A fifteenth aspect is the impedance converter (1) based on the thirteenth or fourteenth aspect. In the fifteenth aspect, the input antenna (31) is positioned so that no discharge occurs between a tip portion (31a) of the input antenna (31) and the cavity (2). The output antenna (41) is positioned so that no discharge occurs between a tip portion (41a) of the output antenna (41) and the cavity (2). This aspect can reduce the influence of discharge between the input antenna (31) and the output antenna (41) and the cavity (2).

[0108] The second to fifteenth aspects are not essential and are optional elements.

[0109] As described above, the embodiment has been described as an example of the technology in the present disclosure. For this purpose, the attached drawings and detailed description have been provided. Therefore, among the components described in the attached drawings and detailed description, not only components essential for solving the problem but also components that are not essential for solving the problem in order to illustrate the above technology may be included. Therefore, just because those non-essential components are described in the attached drawings or detailed description, it should not be immediately determined that those non-essential components are essential. In addition, since the above-mentioned embodiment is intended to illustrate the technology in the present disclosure, various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0110] The present disclosure is applicable to an impedance converter, particularly to an impedance converter for high frequencies. [Explanation of symbols]

[0111] 1 Impedance converter 2 Cavity 20. Interior Space 21 1st wall section 214 Recess 22 Second wall section 23 Third wall 24 4th wall 28 Aperture 3 Input Ports 31 Input Antenna 31a Tip 4 Output Ports 41 Output antenna 41a Tip 5 Adjustment mechanism 6. Stubs 6a Tip 6b Rear end 71 Position adjustment mechanism 711 Moving parts 712 Fixed part 72 Insertion length adjustment mechanism 721 Moving parts 722 Fixed part 8 Electrical Connections 81 First conductive member 82 Second conductive member D11 distance D12 distance

Claims

1. a cavity having an electromagnetically sealed internal space; an input port provided in the cavity for inputting radio waves into the internal space; an output port provided in the cavity for outputting radio waves from the internal space; an adjustment mechanism having a metal stub located within the internal space, the adjustment mechanism adjusting a position of the stub between the input port and the output port and an insertion length of the stub into the internal space; Equipped with Impedance converter.

2. the adjustment mechanism adjusts a position of the stub between the input port and the output port and an insertion length of the stub into the internal space, separately. The impedance converter according to claim 1 .

3. The cavity has a first wall and a second wall in a first direction; the input port is in the first wall portion or the second wall portion; the output port is in the first wall or the second wall; When viewed from the first direction, the input port and the output port are aligned in a second direction perpendicular to the first direction.

3. The impedance converter according to claim 1 or 2.

4. the cavity has an opening in the first wall between the input port and the output port; the stub passes through the opening such that a front end of the stub is located within the internal space and a rear end of the stub is located outside the internal space, The impedance converter according to claim 3 .

5. The opening extends in the second direction, the adjustment mechanism includes a position adjustment mechanism that holds the stub within the opening so as to be movable along the second direction, The position adjustment mechanism includes: a movable part to which the stub is attached; a fixed portion that is fixed to the cavity in the second direction and that holds the movable portion of the position adjustment mechanism so as to be movable in the second direction; having The impedance converter according to claim 4 .

6. the adjustment mechanism includes an insertion length adjustment mechanism that holds the stub movably along the first direction, The insertion length adjustment mechanism includes: a movable part to which the stub is attached; a fixed portion that is fixed to the cavity in the first direction and that holds a movable portion of the insertion length adjustment mechanism so as to be movable in the first direction; having 6. The impedance converter according to claim 4 or 5.

7. The cavity has a recess on a surface of the first wall portion facing the second wall portion, the opening is at the bottom of the recess; the recess has a size capable of accommodating a tip end of the stub such that the tip end of the stub does not protrude from the recess toward the second wall portion in the first direction. The impedance converter according to claim 6 .

8. the adjustment mechanism further comprises an electrical connection portion electrically connecting the stub to the cavity. The impedance converter according to any one of claims 4 to 7.

9. The electrical connection portion is a first conductive member located outside the internal space of the cavity and elastically contacting the stub in a third direction perpendicular to the first direction and the second direction; a second conductive member located outside the internal space of the cavity and electrically connecting the first conductive member to a peripheral portion of the opening of the cavity; Including, The impedance converter according to claim 8 .

10. When viewed from the first direction, the cavity is symmetrical with respect to a line passing through the input port and the output port. The impedance converter according to any one of claims 4 to 9.

11. The cavity has a third wall portion and a fourth wall portion in the second direction, the input port is closer to the third wall portion than the output port; a distance between the input port and the third wall portion and a distance between the output port and the fourth wall portion are equal to each other; The impedance converter according to any one of claims 4 to 10.

12. the input port and the output port are in the first wall portion; The impedance converter according to any one of claims 4 to 11.

13. the input port having an input antenna located within the interior space; the output port having an output antenna located within the interior space; The impedance converter according to any one of claims 1 to 12.

14. The input antenna and the output antenna have the same shape. The impedance converter according to claim 13.

15. the input antenna is positioned so that no discharge occurs between a tip of the input antenna and the cavity; the output antenna is positioned so that no discharge occurs between a tip of the output antenna and the cavity; An impedance converter according to claim 13 or 14.

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