Choke Structure

Abstract

To realize a structure that ensures good isolation in a waveguide two-channel rotary joint, and to solve problems that occur with the structure.SOLUTION: A choke device includes a first choke portion 31 provided on the side of a communicating portion between a fourth waveguide 13 and a hollow hole 112 of a fixed body 11 into which a coaxial waveguide 23 of a rotary waveguide portion is inserted, a second choke portion 32 provided on the side of a communicating portion between the hollow hole 112 of the fixed body 11 and a third waveguide 12, a partition member 33 interposed between the first choke portion 31 and the second choke portion 32 and provided with an inner tube through hole 331 through which an inner tube 231 of the coaxial waveguide 23 passes, and a bearing member 34 that is accommodated inside the second choke portion 32 and supports the inner tube 231 of the coaxial waveguide 23 so as to be axially rotatable, and around the inner tube through hole 331 of the partition member 33, a liquid drain through hole 332 that allows the first choke portion 31 and the second choke portion 32 to communicate with each other is provided.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a choke structure, and to a technique suitable for application to a two-channel waveguide rotary joint used, for example, when connecting waveguides in satellite communication antennas and weather radars. [Background technology]

[0002] Conventionally, as a mechanism for connecting waveguides within equipment used, for example, in satellite communication antennas and weather radars, a waveguide two-channel rotary joint has been known (see Patent Document 1), which includes a first waveguide having a circular or rectangular cross-section, extending in a hollow cylindrical shape, with a partitioned area in the center, with a first propagation path on one side and a second propagation path on the other side disposed within the same tube, and a coaxial tube extending in a direction perpendicular to the first waveguide, connected to the first waveguide and supported for rotation about an axis in the perpendicular direction, with first and second transmission lines in the coaxial line that communicate with the first and second propagation paths, respectively, at the perpendicular axis and perform mode conversion, and in which a short-circuiting plate extending obliquely and partitioning the partitioned area of ​​the first waveguide is provided, a first transmission line of the coaxial tube connected to the short-circuiting plate and communicating with the first propagation path side, and a second transmission line of the coaxial tube that extends around the periphery of the first transmission line and communicates with the second propagation path side (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-255200 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in a composite coaxial structure that transmits two signals separately, it is necessary to ensure good isolation.

[0005] Therefore, an object of the present invention is to provide a choke structure that can realize a structure that ensures good isolation in a waveguide two-channel rotary joint and can solve the problems that arise with the structure. [Means for solving the problem]

[0006] In order to solve the above problems, the choke structure according to the present invention is a choke structure in a waveguide two-channel rotary joint having a rotating waveguide section including a first waveguide and a second waveguide, a fixed body that rotatably supports the rotating waveguide section, and a fixed waveguide section including a third waveguide and a fourth waveguide, the choke structure including a first choke section provided on the side of a communicating section between a hollow hole of the fixed body into which a coaxial tube of the rotating waveguide section is inserted and the fourth waveguide, and a second choke section provided on the side of a communicating section between the hollow hole and the third waveguide. the first choke section being provided on the first side of the coaxial tube; a partition member interposed between the first choke section and the second choke section and having an inner tube through hole through which the inner tube of the coaxial tube passes; and a bearing member housed inside the first choke section or the second choke section and supporting the inner tube of the coaxial tube so as to be freely rotatable about its axis, wherein a liquid drain through hole is provided around the inner tube through hole of the partition member, connecting the first choke section and the second choke section.

[0007] The choke structure of the present invention may be configured so that the dimensions of each portion of the first choke portion and each portion of the second choke portion are different from each other so as to absorb the change in wavelength caused by accommodating the bearing member and so that the first choke portion and the second choke portion have similar electrical characteristics.

[0008] In the choke structure according to the present invention, the partition member may be provided with two to four liquid-draining through holes. Effect of the Invention

[0009] The choke structure of the present invention has two choke portions, a first choke portion and a second choke portion, so that it is possible to realize a structure that reliably ensures sufficient isolation in a waveguide two-channel rotary joint.

[0010] According to the choke structure of the present invention, the partition member interposed between the first and second choke portions is provided with a liquid drainage through hole that connects the first and second choke portions, so that cleaning liquid that has entered the second choke portion can be discharged to the outside, thereby solving problems that arise with a structure having two choke portions, a partition member, and a bearing member.

[0011] The choke structure of the present invention can improve isolation between channels in the same frequency band when the dimensions of each portion of the first choke portion and each portion of the second choke portion are made different from each other so as to absorb the change in wavelength caused by the accommodation of the bearing member and so that the first choke portion and the second choke portion have similar electrical characteristics.

[0012] When the choke structure of the present invention is configured so that a plurality of liquid drainage through holes are provided in the partition member, it becomes possible to more easily and appropriately drain the cleaning liquid that has entered the second choke portion to the outside. [Brief description of the drawings]

[0013] [Figure 1] 1 is a longitudinal sectional view showing a schematic internal structure of a waveguide two-channel rotary joint (particularly, a fixed waveguide portion) in an embodiment having a choke structure according to the present invention. [Diagram 2] FIG. 2 is an enlarged vertical cross-sectional view of a choke structure in the waveguide two-channel rotary joint of FIG. 1. [Diagram 3] 13 is a vertical cross-sectional view of the fixed waveguide portion, illustrating a state in which cleaning liquid remains in the second choke portion (when no liquid drainage through-hole is provided in the partition member). FIG. [Figure 4] 2 is a perspective view showing the structure of a partition member in the choke structure of the waveguide two-channel rotary joint of FIG. 1. FIG. [Diagram 5] 13 is a vertical cross-sectional view of a fixed waveguide portion illustrating the discharge of cleaning liquid in the second choke portion to the outside. FIG. [Figure 6] 1 is a model of a waveguide two-channel rotary joint 1 used in a simulation in a verification example, and is a simulation model for a case in which a through hole for liquid drainage is not provided in a partition member. [Figure 7] 1 is a model of a waveguide two-channel rotary joint 1 used in a simulation in a verification example, and is an example of a simulation model in which two through holes for liquid drainage are provided in a partition member. [Figure 8] 11 is a graph showing a comparison of S parameter S11 (return loss) depending on the presence or absence of a through hole for liquid drainage in the partition member and the shape of the through hole for liquid drainage. [Figure 9] 13 is a graph showing a comparison of S parameter S33 (return loss) depending on the presence or absence of a through hole for liquid drainage in the partition member and the shape of the through hole for liquid drainage. [Figure 10] 11 is a graph showing a comparison of S parameter S21 (insertion loss) depending on the presence or absence of a through hole for liquid drainage in the partition member and the shape of the through hole for liquid drainage. [Figure 11] 11 is a graph showing a comparison of S parameter S43 (insertion loss) depending on the presence or absence of a through hole for liquid drainage in the partition member and the shape of the through hole for liquid drainage. [Figure 12] 11 is a graph showing a comparison of S parameter S13 (isolation) for cases with and without a liquid-drainage through hole in the partition member and for cases of different shapes of the liquid-drainage through hole. [Figure 13] 11 is a graph showing a comparison of S parameter S14 (isolation) depending on the presence or absence of a through hole for liquid drainage in the partition member and the shape of the through hole for liquid drainage. [Figure 14] 11 is a graph showing a comparison of S parameter S23 (isolation) depending on the presence or absence of a through hole for liquid drainage in the partition member and the shape of the through hole for liquid drainage. [Figure 15] 11 is a graph showing a comparison of S parameter S24 (isolation) for cases with and without a liquid-drainage through hole in the partition member and for cases of different shapes of the liquid-drainage through hole. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will be described below based on the illustrated embodiment. In the following description, as shown in the drawings, a vertical axis and a horizontal axis perpendicular to each other are defined for the waveguide two-channel rotary joint 1, and the vertical axis corresponds to up and down, while the horizontal axis corresponds to right and left.

[0015] Fig. 1 is a vertical cross-sectional view showing a schematic internal structure of a two-channel waveguide rotary joint 1 (particularly, a fixed waveguide portion 10) having a choke structure 30 according to an embodiment of the present invention. Fig. 2 is an enlarged vertical cross-sectional view of the choke structure 30 in the two-channel waveguide rotary joint 1.

[0016] This waveguide two-channel rotary joint 1 has a function of mode conversion from TE mode (Transverse Electric mode), which is the fundamental transmission mode of a hollow rectangular waveguide having a rectangular cross section, to TEM mode (Transverse Electromagnetic mode) of a rotatable coaxial line, and mainly has a fixed waveguide section 10 that is fixed and installed on a rotating table of a weather radar, for example, and a rotating waveguide section that is supported on the upper part of this fixed waveguide section 10 so as to be freely rotatable.

[0017] Here, since this invention relates to the fixed waveguide portion 10, and the structure of the rotating waveguide portion is not limited to a specific form as long as it has a coaxial tube 23 that is inserted into the fixed waveguide portion 10, a detailed explanation of the structure of the rotating waveguide portion will be omitted here.

[0018] The rotating waveguide section can be roughly considered to be configured to have, for example, a first waveguide 21 which is fixed to a rotating body which is rotatably supported on the upper part of the fixed waveguide section 10 and is a port which outputs a vertically polarized wave (CH2), a second waveguide 22 which is fixed to the rotating body and is a port which outputs a horizontally polarized wave (CH1), and a coaxial tube 23 which transmits the vertically polarized wave (CH2) to the first waveguide 21 and transmits the horizontally polarized wave (CH1) to the second waveguide 22. As a specific structure of such a rotating waveguide section, for example, the structure disclosed in JP 2013-255200 A (including the structure disclosed as the background art and the structure disclosed as a form for implementing the invention) can be adopted.

[0019] The fixed waveguide section 10 has a fixed body 11 that is fixedly installed, for example, on a rotating base of a weather radar and supports the rotating waveguide section so that it can rotate freely, a third waveguide 12 which is a port for inputting a vertically polarized wave (CH2) transmitted from the rotating base to a coaxial tube 23 arranged within the fixed body 11, and a fourth waveguide 13 which is a port for inputting a horizontally polarized wave (CH1).

[0020] The fixed body 11 is formed with an opening (reference numeral 111) at the upper end, and houses the coaxial tube 23 extending downward from the rotating waveguide section and arranged along the vertical direction, and has a hollow hole 112 communicating with the third waveguide 12 and the fourth waveguide 13. A rotating member (not shown) such as a bearing is attached to the fixed body 11 at a position near the upper end, and the rotating waveguide section is rotatably supported via this rotating member (for example, see the above-mentioned JP 2013-255 A). (See the structure disclosed in Publication No. 200).

[0021] The first to fourth waveguides 21, 22, 12, and 13 are each a TE mode waveguide, which is the fundamental transmission mode of a hollow rectangular waveguide having a rectangular cross section, and communicate with a TEM mode coaxial tube 23 of a rotatable coaxial line extending into the hollow hole 112 of the fixed body 11.

[0022] The coaxial tube 23 has a composite coaxial structure that transmits two polarized waves separately, and is a two-channel coaxial tube in which two transmission lines are formed, using a rotatable coaxial line in the TEM mode, and is housed within the hollow hole 112 of the fixed body 11.

[0023] The coaxial tube 23 has a long inner tube 231 that extends in an elongated cylindrical shape so as to cover the periphery of the rod-shaped central conductor 24, and a short cylindrical outer tube 232 that covers the outside of the upper end portion of the inner tube 231. Note that the coaxial tube 23 and the central conductor 24 are not shown in Figures 2, 3, and 5.

[0024] The coaxial tube 23 also includes a first transmission line 233 formed between the central conductor 24 and the inner tube 231 for transmitting a vertically polarized wave (CH2), and a second transmission line 234 formed between the inner tube 231 and the outer tube 232 for transmitting a horizontally polarized wave (CH1).

[0025] In the coaxial tube 23, an upper end of the first transmission line 233 communicates with the first waveguide 21 of the rotating waveguide section, and a lower end of the first transmission line 233 communicates with the third waveguide 12, and an upper end of the second transmission line 234 communicates with the second waveguide 22 of the rotating waveguide section, and a lower end of the second transmission line 234 communicates with the fourth waveguide 13 via a hollow hole 112 in the fixed body 11. That is, the first waveguide 21 and the third waveguide 12 communicate with each other via an inner tube 231 of the coaxial tube 23 (i.e., the first transmission line 233), and the second waveguide 22 and the fourth waveguide 13 communicate with each other via an outer tube 232 of the coaxial tube 23 (i.e., the second transmission line 234).

[0026] Here, in order to ensure sufficient isolation between the vertically polarized wave (CH2) input and transmitted from the third waveguide 12 and the horizontally polarized wave (CH1) input and transmitted from the fourth waveguide 13, i.e., isolation between channels, a choke structure 30 is provided between the communication portion between the coaxial tube 23 and the third waveguide 12 and the communication portion between the coaxial tube 23 and the fourth waveguide 13.

[0027] In order to reliably secure sufficient isolation between channels, the choke structure 30 has two choke sections: a first choke section 31 provided on the side (i.e., the upper side) of the communication section (called "first communication section 131") between the hollow hole 112 of the fixed body 11 and the fourth waveguide 13, and a second choke section 32 provided on the side (i.e., the lower side) of the communication section (called "second communication section 121") between the hollow hole 112 of the fixed body 11. The first choke section 31 and the second choke section 32 are provided between the first communication section 131 and the second communication section 121 as hollow spaces that communicate with the hollow hole 112 of the fixed body 11.

[0028] For convenience of molding and assembly, fixed waveguide section 10 is constructed by combining a number of parts, and in relation to choke structure 30, the side on which first choke section 31 is provided and the side on which second choke section 32 is provided are each formed as separate parts (the symbol BS in Figures 1, 3 and 5 indicates the joint surface between the parts).

[0029] The choke structure 30 according to the embodiment is a choke structure in a waveguide two-channel rotary joint 1 having a rotating waveguide section including a first waveguide 21 and a second waveguide 22, a fixed body 11 that rotatably supports the rotating waveguide section, and a fixed waveguide section 10 that includes a third waveguide 12 and a fourth waveguide 13, and the coaxial tube 23 of the rotating waveguide section The coaxial tube 23 has a first choke portion 31 provided on the side of the communication between hollow hole 112 of fixed body 11 to be inserted and fourth waveguide 13, a second choke portion 32 provided on the side of the communication between hollow hole 112 of fixed body 11 and third waveguide 12, a partition member 33 interposed between the first choke portion 31 and the second choke portion 32 and provided with an inner tube through hole 331 through which inner tube 231 of coaxial tube 23 passes, and a bearing member 34 housed inside second choke portion 32 and supporting inner tube 231 of coaxial tube 23 so as to be rotatable about its axis, and a liquid drain through hole 332 connecting the first choke portion 31 and the second choke portion 32 is provided around inner tube through hole 331 of partition member 33.

[0030] The first choke portion 31 is provided as a hollow space having a first choke portion space 311 and a first choke groove 312, and the second choke portion 32 is provided as a hollow space having a second choke portion space 321 and a second choke groove 322.

[0031] On the side of first communicating portion 131 within fixed body 11, first choke portion space 311 is formed as a hollow space that is circular in plan view and has a predetermined height, in other words, as a cylindrical hollow space.

[0032] First choke groove 312 is formed as an annular groove recessed upward from the peripheral edge of the upper surface / top surface of first choke portion space 311 and therefore open at the bottom.

[0033] On the side of second communicating portion 121 within fixed body 11, second choke portion space 321 is formed as a hollow space that is circular in plan view and has a predetermined height, in other words, as a cylindrical hollow space.

[0034] Second choke groove 322 is formed as an annular groove recessed downward from the peripheral edge of the lower surface / bottom surface of second choke portion space 321 and therefore has an open upper surface.

[0035] The bearing member 34 is a member that supports the inner tube 231 of the coaxial tube 23 so that the inner tube 231 is axially rotatable. The bearing member 34 has a disk-like base, a through hole 341 for passing the inner tube 231 of the coaxial tube 23 through at the center in a plan view, and an annular protrusion that protrudes downward from the peripheral portion of the lower surface / bottom surface.

[0036] The bearing member 34 is housed within the second choke portion 32 with the downward annular protrusion inserted into the second choke groove 322 .

[0037] The material of the bearing member 34 is not limited to a particular type, but may be, for example, polytetrafluoroethylene (PTFE).

[0038] Here, by accommodating bearing member 34 in second choke portion 32, a change in wavelength occurs in second choke portion 32 due to the difference in dielectric constant between the material constituting bearing member 34 and the metal material constituting fixed waveguide portion 10. For example, if bearing member 34 is made of a material having a higher dielectric constant than the metal material constituting fixed waveguide portion 10 (specifically, for example, polytetrafluoroethylene (PTFE)), accommodating bearing member 34 in second choke portion 32 causes wavelength shortening in second choke portion 32.

[0039] Therefore, in order to ensure good isolation between channels in the same frequency band, the first choke portion 31 and the second choke portion 32 are provided as hollow spaces having different sizes (i.e., the dimensions of each of the choke portion spaces 311, 321 and the choke grooves 312, 322). The dimensions of each choke structure are adjusted relative to one another to absorb the change in wavelength caused by the accommodation of the bearing member 34 so that the first choke portion 31 and the second choke portion 32 have similar electrical characteristics, thereby improving isolation between channels in the same frequency band.

[0040] Partition member 33 is interposed between first choke portion 31 and second choke portion 32, and separates first choke portion space 311 and second choke portion space 321.

[0041] The partition member 33 has a disk-like base and has an inner tube through hole 331 for passing the inner tube 231 of the coaxial tube 23 through it at the center in a plan view.

[0042] Here, when assembling the fixed waveguide section 10, a plurality of pieces are combined and brazed to the joint surfaces BS of the pieces to ensure airtightness. In order to remove the flux after brazing, it is practically impossible to wipe it off with, for example, alcohol-soaked absorbent cotton and tweezers, because the mechanical structure of the assembled fixed waveguide section 10 is complex, and it is necessary to dissolve the assembled fixed waveguide section 10 by immersing it in a specified cleaning solution.

[0043] When the flux is dissolved by immersion in a cleaning solution, the flux does not dissolve unless it is immersed in the cleaning solution at a high temperature, so the assembled fixed waveguide section 10 is immersed in the cleaning solution at a high temperature. In this case, the temperature of the assembled fixed waveguide section 10 drops rapidly when immersed in the cleaning solution, so that the cleaning solution that has penetrated into the hollow hole 112 of the fixed body 11 penetrates into the second choke section 32 from the boundary between the bearing member 34 and the surrounding metal material (specifically, the second choke section 32), and on the other hand, even if the assembled fixed waveguide section 10 is taken out of the cleaning solution after a predetermined time of immersion, the cleaning solution is not discharged from the boundary between the bearing member 34 and the surrounding metal material, and the cleaning solution remains in the second choke section 32 (see FIG. 3).

[0044] Therefore, two liquid drainage through holes 332 are provided in the partition member 33 at positions around the inner tube through hole 331 that at least partially overlap with the second choke portion 32 in a plan view (in other words, in the vertical direction) (see Figs. 1, 2 and 4). Note that the number of liquid drainage through holes 332 provided in the partition member 33 is not limited to two, and may be one, or may be three or more.

[0045] The liquid drainage through hole 332 is provided so as to communicate between the first choke portion 31 and the second choke portion 32, and further so as to communicate between the hollow hole 112 of the fixed body 11 and the second choke portion 32.

[0046] As a result, the cleaning liquid that has entered the second choke portion 32 passes through the liquid drainage through hole 332 of the partition member 33, the first choke portion 31, and the hollow hole 112 of the fixed body 11, and is discharged to the outside through the opening 111 at the upper end of the fixed waveguide portion 10 (see Figure 5).

[0047] In order to allow the cleaning liquid that has entered the second choke portion 32 to be more easily and appropriately discharged to the outside, it is preferable that a plurality of liquid drainage through holes 332 be provided in the partition member 33. Furthermore, in consideration of controlling the effect on the electrical characteristics of the rotary joint to an appropriate extent, it is preferable that about two to four liquid drainage through holes 332 be provided in the partition member 33.

[0048] According to the choke structure 30 of the embodiment, since it has two choke portions, namely, the first choke portion 31 and the second choke portion 32, it is possible to realize a structure that reliably ensures sufficient isolation in a waveguide two-channel rotary joint. It becomes Noh.

[0049] According to the choke structure 30 of the embodiment, further, the partition member 33 interposed between the first choke portion 31 and the second choke portion 32 is provided with a liquid drainage through hole 332 which connects the first choke portion 31 and the second choke portion 32. This makes it possible to drain the cleaning liquid that has entered the second choke portion 32 to the outside of the fixed waveguide portion 10, and makes it possible to solve the problems that arise with a structure having two choke portions 31 and 32, the partition member 33, and the bearing member 34.

[0050] Furthermore, according to the choke structure 30 of the embodiment, the dimensions of each portion of the first choke portion 31 and each portion of the second choke portion 32 are made different from each other so that the change in wavelength caused by the accommodation of the bearing member 34 is absorbed and the first choke portion 31 and the second choke portion 32 have similar electrical characteristics, thereby making it possible to improve isolation between channels in the same frequency band.

[0051] Furthermore, according to the choke structure 30 of the embodiment, a plurality of through holes 332 for draining liquid are provided in the partition member 33, so that the cleaning liquid that has entered the second choke portion 32 can be discharged to the outside more easily and appropriately.

[0052] A verification example of the choke structure according to the present invention will be described below with reference to FIGS.

[0053] In this verification example, a simulation was performed using a model of the waveguide two-channel rotary joint 1 to obtain S parameters, thereby understanding and verifying the effect on the electrical characteristics of the rotary joint due to the provision of the liquid drainage through-hole 332 in the partition member 33.

[0054] The model of the waveguide two-channel rotary joint 1 used in the simulation of this verification example is shown in Figures 6 and 7. Figure 6 is a simulation model in which the partition member 33 is not provided with a liquid-draining through-hole 332. Figure 7 is an example of a simulation model in which the partition member 33 is provided with a liquid-draining through-hole 332, specifically, an example of a simulation model in which two liquid-draining through-holes 332 are provided.

[0055] In this verification example, the ports 1 to 4 in the simulation were associated with the first to fourth waveguides 21, 22, 12, and 13, respectively, as follows: Port 1: Second waveguide 22 (port that outputs horizontally polarized wave (CH1)) Port 2: 4th waveguide 13 (port for inputting horizontally polarized wave (CH1)) Port 3: First waveguide 21 (port that outputs vertically polarized wave (CH2)) Port 4: Third waveguide 12 (port for inputting vertically polarized wave (CH2))

[0056] In this verification example, in order to grasp and verify the effect on the electrical characteristics of the rotary joint due to the provision of the liquid-drainage through-holes 332 in the partition member 33, S parameters were compared for cases in which the liquid-drainage through-holes 332 were not provided and cases in which the liquid-drainage through-holes 332 were provided. Also, in order to grasp and verify the effect due to differences in the number and diameter of the liquid-drainage through-holes 332, cases (called "shape cases") in which the liquid-drainage through-holes 332 were provided with two holes with diameters of φ2 mm, φ3 mm, φ4 mm, φ5 mm, φ6 mm, and φ7 mm, and with four holes with diameters of φ7 mm were set.

[0057] FIG. 8 shows the results of a comparison of the S-parameter S11 (i.e., return loss) depending on the presence or absence of the liquid-draining through hole 332 in the partition member 33 and the shape of the liquid-draining through hole 332, and FIG. 9 shows the results of a comparison of the S-parameter S33 (i.e., return loss).

[0058] From the results shown in Figures 8 and 9, it was confirmed that the behavior and degree of the return loss by frequency do not change significantly depending on the presence or absence of the liquid drainage through-holes 332. From the results shown in Figures 8 and 9, it was also confirmed that the behavior and degree of the return loss by frequency do not change significantly depending on the number and diameter of the liquid drainage through-holes 332, at least within the range of the shape cases set in this verification example. In either case, the return loss standard is satisfied in a predetermined frequency band (approximately 9 to 10 GHz) including the center frequency of 9.5 GHz in the specifications in the simulation here.

[0059] The results of a comparison of S-parameter S21 (i.e., insertion loss) for the presence or absence of liquid-drainage through-holes 332 in the partition member 33 and for different shapes of the liquid-drainage through-holes 332 are shown in Fig. 10, and the results of a comparison of S-parameter S43 (i.e., insertion loss) are shown in Fig. 11. Note that, in comparing the S-parameters S21 and S43, no shape case was set for four holes with a diameter of φ7 mm for the arrangement of the liquid-drainage through-holes 332.

[0060] From the results shown in Figures 10 and 11, it was confirmed that the behavior and degree of the insertion loss by frequency do not change significantly depending on the presence or absence of the liquid-discharge through-holes 332. From the results shown in Figures 10 and 11, it was also confirmed that the behavior and degree of the insertion loss by frequency do not change significantly depending on the number and diameter of the liquid-discharge through-holes 332, at least within the range of the shape cases set in this verification example. In either case, the insertion loss standard is satisfied in a predetermined frequency band (approximately 9 to 10 GHz) including the center frequency of 9.5 GHz in the specifications in the simulation here.

[0061] FIG. 12 shows the results of a comparison of S-parameter S13 (i.e., isolation) depending on the presence or absence of liquid-drainage through-hole 332 in partition member 33 and the shape of liquid-drainage through-hole 332. FIG. 13 shows the results of a comparison of S-parameter S14 (i.e., isolation). FIG. 14 shows the results of a comparison of S-parameter S23 (i.e., isolation). FIG. 15 shows the results of a comparison of S-parameter S24 (i.e., isolation).

[0062] From the results shown in FIG. 12 to FIG. 15, it was confirmed that the isolation standard was satisfied in all cases, at least within the range of shape cases set in this verification example.

[0063] From the results of the above verification example, it was confirmed that even if an inner tube through hole 331 is provided in partition member 33, which is interposed between first choke portion 31 and second choke portion 32 and separates first choke portion space 311 and second choke portion space 321, there is no significant effect on the electrical characteristics of the rotary joint, and that performance that satisfies the isolation standards can be achieved.

[0064] Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there are design changes and the like within the scope of the gist of the present invention, they are included in the present invention.

[0065] Specifically, in the above embodiment, the choke structure of the present invention is applied to a two-channel waveguide rotary joint 1 whose schematic structure is shown in FIG. 1, but the structure of the two-channel rotary joint to which the choke structure of the present invention can be applied is not limited to the two-channel waveguide rotary joint 1 whose schematic structure is shown in FIG. 1, and the choke structure of the present invention may be applied to two-channel waveguide rotary joints of other structures.

[0066] In the above embodiment, the bearing member 34 is accommodated in the second choke portion 32. However, bearing member 34 may be accommodated in first choke portion 31. In this case, cleaning liquid remains in first choke portion 31, and cleaning liquid that has entered first choke portion 31 passes through liquid drainage through hole 332 of partition member 33, second choke portion 32, and hollow hole 112 of fixed body 11, and is discharged to the outside from opening 111 at the upper end of fixed waveguide portion 10. [Explanation of symbols]

[0067] 1 Waveguide 2-Channel Rotary Joint 10 Fixed waveguide section 11 Fixed body 111 Opening 112 Hollow hole 12 Third Waveguide 121 Second connecting part 13 4th Waveguide 131 First communication part 21 First Waveguide 22 Second Waveguide 23 coaxial tube 231 Inner tube 232 Outer tube 233 First Transmission Line 234 Second Transmission Line 24 Center conductor 30 Choke Structure 31 First Choke Section 311 First choke space 312 First choke groove 32 Second Choke Section 321 Second Choke Space 322 Second Choke Groove 33 Partitioning material 331 Through hole for inner pipe 332 Through hole for liquid drainage 34 Bearing materials 341 Through hole BS joint surface

Claims

1. A choke structure in a waveguide two-channel rotary joint having a rotating waveguide section including a first waveguide and a second waveguide, a fixed body that rotatably supports the rotating waveguide section, and a fixed waveguide section that includes a third waveguide and a fourth waveguide, a first choke portion provided on a side of a communication portion between a hollow hole of the fixed body into which a coaxial tube of the rotary waveguide portion is inserted and the fourth waveguide; a second choke portion provided on a side of a communicating portion between the hollow hole and the third waveguide; a partition member interposed between the first choke portion and the second choke portion and including an inner tube through hole through which an inner tube of the coaxial tube passes; a bearing member that is accommodated in the first choke portion or the second choke portion and supports the inner tube of the coaxial tube so as to be rotatable about an axis thereof, a through hole for draining liquid that communicates with the first choke portion and the second choke portion is provided around the through hole for the inner tube of the partition member; A choke structure characterized by:

2. The dimensions of each portion of the first choke portion and each portion of the second choke portion are different from each other so that the first choke portion and the second choke portion have similar electrical characteristics by absorbing a change in wavelength caused by accommodating the bearing member.

2. The choke structure according to claim 1 .

3. The partition member has two to four liquid drainage through holes.

3. The choke structure according to claim 1 or 2.

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