Pillbox-type transmission window and its manufacturing method

Abstract

To suppress a ghost mode in a pillbox type transmission window.SOLUTION: A pillbox type transmission window comprises an input / output window of a microwave tube. The pillbox type transmission window comprises: a disc-shaped member 1 in which a metalize layer is formed in an outer peripheral portion of disc-shaped ceramics; a pair of annular members 2 consisting of a metal having an outer diameter substantially equal to that of the disc-shaped member 1 and integrated with the outer peripheral portion of the disc-shaped member 1 while being disposed with the disc-shaped member 1 interposed from both sides; a cylindrical member 3 consisting of a metal having an inner diameter substantially equal to the outer diameter of the pair of annular members 2 and the disc-shaped member 1 and holding the pair of metal components and the disc-shaped member inside; and a regulation member 4 by which, between the annular members and the cylindrical member, the rotations thereof are suppressed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pillbox-type transmission window and a method for making the same. [Background technology]

[0002] In recent years, the frequencies used in communications and broadcasting have become higher and wider in order to increase the capacity and speed of communications and broadcasting. In particular, the fields of satellite broadcasting and satellite communications require high-power amplifiers with characteristics such as high output and wide bandwidth, and traveling-wave tube amplifiers are used for these. A traveling-wave tube has a vacuum section inside, and a component called a high-frequency window in the high-frequency transmission path that separates the vacuum section from the atmospheric pressure section.

[0003] Among these high-frequency windows, pillbox-type high-frequency windows, which have a dielectric sandwiched in the high-frequency transmission path, are widely used as high-power high-frequency windows. However, pillbox-type high-frequency windows are known to generate unwanted resonances called ghost modes due to the dielectric and the high-frequency window structure, which is an obstacle to broadening the bandwidth. Patent Document 1 has been filed as a technique relating to pillbox-type waveguide windows used as input / output windows for such microwaves. Patent Document 1 discloses a technology for providing a pillbox-type vacuum window as an input / output window for RF (radio frequency) signals in a microwave tube for two purposes: reducing loss of the RF signal and sealing the inside of the microwave tube in a vacuum.

[0004] In the pillbox-type high-frequency window, ghost modes may occur. When ghost modes occur, the frequency characteristics of the gain and group delay deviation of the traveling-wave tube and the return loss may deteriorate, which may result in poor communication quality. In addition, when the dielectric material heats up due to power loss caused by the ghost modes, and cracks occur due to stress caused by thermal expansion resulting from the heat generation, the high-frequency window's original function of separating the vacuum part from the atmospheric pressure part may be impaired. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-287382 A

[0006] Incidentally, one way to deal with the occurrence of the ghost mode is to prepare multiple types of components, select from a large number of components a combination of which is unlikely to cause a ghost mode in the frequency band being used, and select from among them. However, there is a problem in that the loss that occurs with the selection of appropriate components is one factor that prevents the cost of traveling-wave tubes from being reduced. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a pillbox type vacuum window capable of suppressing the occurrence of ghost modes. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention proposes the following means. The pillbox-type transmission window of the present invention is a pillbox-type transmission window that constitutes an input / output window of a microwave tube, and comprises a disk-shaped member having a metallized layer formed on the outer periphery of a disk-shaped ceramic, a pair of annular members made of metal having approximately the same outer diameter as the disk-shaped member and arranged to sandwich the disk-shaped member from both sides and integrated with the outer periphery of the disk-shaped member, a tubular member made of metal having an inner diameter approximately equal to the outer diameters of the pair of annular members and the disk-shaped member, which holds the pair of metal parts and the disk-shaped members inside, and a regulating member that suppresses rotation between the annular members and the tubular members.

[0009] The manufacturing method of the pillbox-type transmission window according to the present invention is a manufacturing method of a pillbox-type transmission window having an input / output window of a microwave tube, and includes the steps of: constructing a disk-shaped member having a metallized layer formed on the outer periphery of a disk-shaped ceramic; constructing a pair of annular members out of metal having approximately the same outer diameter as the disk-shaped member; sandwiching the disk-shaped member from both sides with the annular members to bond them together; and arranging the pair of annular members and the disk-shaped members inside a tubular member formed of metal having an inner diameter approximately equal to the outer diameters of the pair of annular members and the disk-shaped members, and further including the step of positioning the annular members in the circumferential direction relative to the tubular member by a regulating member that suppresses rotation between the annular members and the tubular member prior to the step of arranging the pair of annular members and the disk-shaped members inside the tubular member. Effect of the Invention

[0010] The present invention makes it possible to suppress ghost modes in a pillbox-type transmission window. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view of an example of a minimum configuration of a pillbox-type transmission window according to the present invention. [Diagram 2] 1 is a process diagram of a minimum configuration example of a method for manufacturing a pillbox-type transmission window according to the present invention. FIG. [Diagram 3] FIG. 1 is a perspective view of a pillbox-style transmission window in accordance with one embodiment of the present invention. [Figure 4] FIG. 13 is a perspective view of a pillbox-type transmission window of a comparative example of an embodiment. [Diagram 5] 11 is a table showing loss characteristics of pillbox-type transmission windows in an embodiment and a comparative example at rotation angles of 0°, 4°, and 10°. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A pillbox-type transmission window according to an example of a minimum configuration of the present invention will be described with reference to FIG. The pillbox-type transmission window in this minimum configuration is a pillbox-type transmission window having an input / output window of a microwave tube, and includes a disk-shaped member 1 having a metallized layer formed on the outer periphery of a disk-shaped ceramic, a pair of annular members 2 made of metal having approximately the same outer diameter as the disk-shaped member 1 and arranged to sandwich the disk-shaped member 1 from both sides and integrated with the outer periphery of the disk-shaped member 1, a tubular member 3 made of metal having an inner diameter approximately equal to the outer diameters of the pair of annular members 2 and the disk-shaped member 1, and holding the pair of metal parts and the disk-shaped member inside, and a regulating member 4 that suppresses rotation between the annular members and the tubular member.

[0013] In the pillbox-type transmission window configured as above, the annular member 2 is attached together with the ceramic disk-shaped member 1 in a state in which their rotation is restricted relative to the cylindrical member 3 by the restricting member 4. As a result, unnecessary resonance caused by deviation in the rotation direction can be suppressed.

[0014] A method for manufacturing a pillbox-type transmission window according to the minimum configuration of the present invention will be described with reference to FIGS. A manufacturing method of a pillbox-type transmission window that constitutes an input / output window of a microwave tube according to this minimum configuration includes a step SP1 of constructing a disk-shaped member 1 having a metallized layer formed on the outer periphery of a disk-shaped ceramic, a step SP2 of constructing a pair of annular members 2 out of a metal having approximately the same outer diameter as the disk-shaped member 1, a step SP3 of sandwiching the disk-shaped member 1 with the annular members 2 to integrally bond it to each other, and a step of arranging the pair of annular members 2 and the disk-shaped member 1 inside a cylindrical member 3 made of a metal having an inner diameter approximately equal to the outer diameters of the pair of annular members 2 and the disk-shaped member 1, and further includes a step of positioning the annular member 2 in the circumferential direction with respect to the cylindrical member 3 by a regulating member 4 that suppresses rotation between the annular member 2 and the cylindrical member 3, prior to the step of arranging the pair of annular members 2 and the disk-shaped member 1 inside the cylindrical member 3.

[0015] According to the above manufacturing method, the pillbox-type transmission window is attached in a state in which the rotation of the annular member is restricted relative to the cylindrical member by the restricting member 4. As a result, unnecessary resonance caused by deviation in the rotational direction can be suppressed.

[0016] A configuration according to one embodiment of the present invention will be described with reference to Figures 3 to 5. Note that the same reference numerals are used to designate the same components as in Figure 1, and the description will be simplified. This pillbox-shaped transmission window is connected midway through the high-frequency circuit (vacuum region) of the traveling-wave tube, and functions as an entrance for introducing microwaves into the vacuum or an entrance for extracting them into the atmosphere.

[0017] The pillbox-type transmission window of one embodiment has a disk-shaped member 1 having a main body 1a made of a disk-shaped ceramic and a metallized layer formed on an outer circumferential portion 1b of the main body 1a, as in the above-mentioned minimum configuration example. The annular members 2A are disposed on both sides of the disk-shaped member 1 to sandwich the disk-shaped member 1 from both sides. The annular member 2A has an annular main body 20 made of metal, and one surface of the annular main body 20 has a rectangular waveguide 21 made of an integral metal in a square cylindrical shape. One of the rectangular waveguides 21 of the pair of annular members 2A is connected to a high-frequency circuit (vacuum region), and the other rectangular waveguide 21 is connected to an atmospheric pressure region.

[0018] The cylindrical member 3A is made of metal having an inner diameter approximately equal to the outer diameter of the pair of annular members 2A and the disk-shaped member 1, and is configured in a cylindrical shape to hold the pair of annular members 2A and the disk-shaped member 1 inside. The cylindrical member 3A has a notch 41 arranged to divide the entire member into two half-cylinder shapes. The notch 41 divides the cylindrical member 3A into upper and lower regions so that each half is in a half shape. The notch 41 penetrates the cylindrical member 3A in a direction parallel to the axis C at the outer periphery, and penetrates the cylindrical member 3A in the radial direction at a position near one side surface. The dimension of the notch 41 is set to a size that allows the protrusion 40 to pass through. The protrusion 40 and the notch 41 form a restricting portion that restricts the rotation of the disk-shaped member 1A and the cylindrical member 3A around the axis C.

[0019] The pillbox-type transmission window having the above-mentioned configuration is manufactured by forming the disk-shaped member 1, the annular member 2A, and the cylindrical member 3A into the shapes shown in FIG. 3, and then assembling them according to the following steps. The disk-shaped member 1 is sandwiched between a pair of annular members 2A, and the metallized portions on the outer periphery are brazed to be integrated. Here, the pair of annular members 2A are assembled by aligning the positions of the protrusions 40 with each other in the circumferential direction. The projection 40 is aligned with the notch 41 of the cylindrical member 3A, and the integrated disk-shaped member 1 and annular member 2A are inserted into the cylindrical member 3A. The disk-shaped member 1 and the annular member 2A are positioned in the cylindrical member 3A in the rotation direction about the axis C by inserting the protrusions 40 into the cutouts 41. The disk-shaped member 1 and the annular member 2A are integrally fixed to the cylindrical member 3A by brazing. The pillbox-type transmission window constructed as described above is used by connecting one side of the rectangular waveguide 21 to the high-frequency circuit (vacuum region) extending from the electron gun to the collector, and connecting the other rectangular waveguide 21 to circuit components or the like on the open-to-atmosphere side, for example, to connect electronic components that input and output RF signals to the high-frequency circuit.

[0020] The operation of the pillbox-type transmission window of the embodiment will be described in comparison with a comparative example shown in FIG. First, a pillbox-type transmission window as a comparative example will be described with reference to FIG. The pillbox-type transmission window shown in FIG. 4 has a configuration in which a disk-shaped member 1 made of a plate-shaped ceramic is sandwiched between a pair of annular members 2B from both sides. The annular member 2B has an annular body 20' made of metal (without protrusions like the annular body of the first embodiment), and one surface of the annular body 20' has a rectangular waveguide 21 made of an integral metal.

[0021] In the pillbox-type transmission window of this comparative example, since no restricting member consisting of a protrusion and a notch is provided, the parts constituting the high frequency window may shift in the rotational direction (direction around the axis C) during assembly.

[0022] This deviation in the rotation direction also generates ghost modes. Figure 5 shows examples of measurements of characteristics (magnitude of return loss caused by ghost modes) when a pillbox-type transmission window of the comparative example is used and deviations (rotation angles) in the rotation direction are 4° and 10°, and when the pillbox-type transmission window of the embodiment is used and assembled with no deviation in the rotation direction (0°).

[0023] As shown in FIG. 5, by using the pillbox-type transmission window of one embodiment, when the rotation angle is set to 0°, the loss is minimized at a frequency of 51 GHz (gigahertz). In contrast, in an analysis example in which a pillbox-shaped transmission window of the comparative example is used and the rotation angle is 4°, the loss is maximum at a frequency slightly higher than 51 GHz, and the loss is minimum on both the lower and higher frequency sides of 51 GHz. Also, in a measurement example in which the rotation angle is 10°, the loss is maximum at a frequency slightly higher than 51 GHz, and the loss is minimum on both the lower and higher frequency sides of 51 GHz compared to the case of the rotation angle of 4°. However, it can be seen that whether the comparative example pillbox-type transmission window is used and the rotation angle is 4° or 10°, the minimum loss is greater than when the pillbox-type transmission window of one embodiment is used and the rotation angle is 0°.

[0024] As described above, the pillbox-type radio frequency window of one embodiment is a pillbox-type radio frequency window to which a support part is added, and differs from a general pillbox-type radio frequency window in that the radio frequency transmission part and the support part have a concave-convex structure to restrict rotation. Therefore, by fitting this concave-convex structure during assembly, it is possible to suppress changes in the angle of the rotation direction of each part, and to suppress the adverse effects of ghost modes on the band of use.

[0025] In addition, according to the pillbox-type transmission window according to the structure and manufacturing method of one embodiment, the following structural features can provide advantageous effects and achieve the objectives. (1) A concave-convex structure is provided in a direction perpendicular to the axis C. This feature makes it possible to achieve a simple structure using ceramic with a simple circular shape similar to that of the comparative example, which can contribute to improved productivity and lower costs. (2) A convex structure is provided on the high-frequency transmission component, and a concave structure is provided on the support component. This feature eliminates the need for cutting out the ceramic, which is required when creating a concave structure in a high-frequency transmission component and a convex structure in a support component, and eliminates the risk of cracks progressing from the cutout, which can contribute to improved productivity. As a result, traveling wave tubes with pillbox-type transmission windows can be manufactured at low cost.

[0026] Furthermore, the present invention can be used not only for pillbox-type high-frequency windows for traveling-wave tubes, but also for all electron tubes that have a vacuum section, such as klystrons and gyrotrons.

[0027] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design modifications and the like are also included within the scope of the present invention that does not deviate from the gist of the present invention. [Industrial Applicability]

[0028] The present invention can be used in high-frequency transmission devices. [Explanation of symbols]

[0029] 1 Disc-shaped member 1a Main unit 1b Outer area 2, 2A, 2B Annular member 3, 3A Cylindrical member 4. Regulatory components 20, 20' Annular body 21 Rectangular waveguide 40 protrusions 41 Cutout

Claims

1. A pillbox-type transmission window having an input / output window of a microwave tube, a disk-shaped member having a metallized layer formed on an outer periphery of a disk-shaped ceramic; a pair of annular members made of metal having the same outer diameter as the disk-shaped member, disposed to sandwich the disk-shaped member from both sides and integrated with an outer periphery of the disk-shaped member; a cylindrical member made of metal having an inner diameter equal to the outer diameters of the pair of annular members and the disk-shaped member and large enough to accommodate the pair of annular members and the disk-shaped member, the cylindrical member holding the pair of metal parts and the disk-shaped member inside; a restricting member that restricts rotation between the annular member and the cylindrical member; A pillbox type transmission window having a

2. The regulating member is A convex portion protruding radially outward from the annular member; a notch formed in the cylindrical member and into which the protrusion is inserted; 2. The pillbox-type transmission window of claim 1, comprising:

3. The protrusions are provided so as to protrude radially outward from a plurality of locations on the outer periphery of the annular member, 3. The pillbox-type transmission window of claim 2.

4. 4. A pillbox-type transmission window according to claim 1, wherein one surface of the annular member faces the disk-shaped member and the other surface of the annular member is connected to a vacuum region of a high-frequency circuit.

5. A method for manufacturing a pillbox-type transmission window having an input / output window of a microwave tube, comprising the steps of: forming a disk-shaped member by forming a metallized layer on an outer periphery of a disk-shaped ceramic; forming a pair of annular members from metal having the same outer diameter as the disk-shaped member; a step of sandwiching the disk-shaped member from both sides with the annular member to integrally join the disk-shaped member; a step of arranging the pair of annular members and the disk-shaped member inside a cylindrical member made of metal and having an inner diameter equal to the outer diameters of the pair of annular members and the disk-shaped member and large enough to accommodate the pair of annular members and the disk-shaped member; and a step of positioning the annular members in a circumferential direction relative to the cylindrical member by a restricting member that restricts rotation between the annular members and the cylindrical member, before the step of arranging the pair of annular members and the disk-shaped member inside the cylindrical member; A method for manufacturing a pillbox-type transmission window.

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