JPH0214114Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of an input/output coupling device for a traveling wave tube, particularly a high-power helical traveling wave tube.

In a helical traveling wave tube, a coaxial tube with a coaxial window hermetically sealed with ceramic is connected to the end of the slow wave circuit, and a waveguide is further connected to this coaxial window by coaxial waveguide conversion. Input/output coupling devices are commonly used.

In particular, as an input/output coupling device for a high-output helical traveling wave tube, the structure shown in FIGS. 1 and 2 is well known. In FIG. 1, one end of the coaxial inner conductor 4 is connected to the helix 3, and the other end is connected to the wall 7 of the waveguide 2. On the other hand, a ceramic plate 6 is placed between the coaxial inner conductor 4 and the coaxial outer conductor 5.
The coaxial window 1 is formed by soldering and vacuum sealing. In such a configuration, heat generated in the helix is transmitted to the coaxial inner conductor 4 by conduction, and heat is generated due to Joule loss of high frequency waves passing through the coaxial window 1. In particular, the temperature of the coaxial inner conductor of the output coupling device of a high-output traveling wave tube becomes high. Therefore, if heat dissipation from the coaxial inner conductor is poor and the temperature becomes too high, thermal expansion strain will be applied to the ceramic plate of the coaxial window due to the temperature difference between the coaxial inner conductor and the outer conductor, causing it to crack or break. This causes problems such as the surface of the inner conductor being oxidized in the outside atmosphere and high frequency discharge occurring between the inner conductor and the outer conductor.

In order to prevent such problems, in the configuration shown in FIG. 1, the coaxial inner conductor 4 is connected to the waveguide wall 7 to improve heat dissipation, and the wall thickness of the waveguide wall 7 is made thinner. The elongation due to thermal expansion of the coaxial inner conductor 4 is absorbed by the deformation of the waveguide wall 7, so that no force is applied to the ceramic plate 6. however,
In the structure shown in FIG. 1, in order to achieve broadband impedance matching in the coaxial waveguide conversion section, it is necessary to increase the thickness of the portion of the coaxial conductor inside the waveguide. As a result, the area where the wall thickness of the waveguide can be made thinner becomes smaller, which has the disadvantage that the deformation of this area makes it impossible to absorb the elongation due to thermal expansion of the coaxial inner conductor as described above. .

In order to overcome these drawbacks, an input/output coupling device having a structure as shown in FIG. 2 is known. In FIG. 2, a thread is cut on the outer periphery of the post 8, and the post 8 is screwed into the waveguide 2. The post 8 is also provided with a hole 9 through which the coaxial inner conductor 4 extending from the coaxial window 1 passes, and a threaded hole 10 into which a circular tube 11 having a thread cut on the outer periphery is screwed. The coaxial inner conductor 4 passes through a hole 9 in the post 8 and is engaged with a hole in a circular tube 11 screwed into the post 8. Circular tube 1
A slot is provided in the thin wall portion 12 of 1 to provide a spring action, and due to this spring action, the circular pipe 11
and the coaxial inner conductor 4 are in contact with each other. Coaxial inner conductor 4
and the post 8 are connected by a chi-yoke coupling by selecting the length l ₁ of the hole 9 of the post 8 and the length l ₂ of the screw hole 10 to be one quarter of the wavelength of the frequency used.

However, in the input/output coupling device having such a structure, since the post and the waveguide are screw-fitted, there is a risk that rattling may occur and high frequency leakage may occur from the contact portion between the two. In addition, if the contact is insufficient, the temperature will rise due to the generation of heat due to the Joule loss of the current flowing through the surface, and the surface will oxidize, further worsening the contact and causing poor heat dissipation. This will eventually lead to damage to the ceramic plate of the coaxial window. The same can be said of the contact portion between the slotted portion of the circular tube and the coaxial inner conductor, and the contact portion between the post and the circular tube.

The object of the present invention is to use such a conventional high-output helical traveling wave tube input/output coupling device. Eliminating defects in the coaxial waveguide conversion section where the coaxial inner conductor is connected to the waveguide wall, broadband impedance matching can be achieved, the elongation due to thermal expansion of the coaxial inner conductor can be absorbed, and good heat dissipation can be achieved. The object of the present invention is to provide an input/output coupling device that allows

In this invention, a post inserted into a waveguide and a coaxial inner conductor extended from a coaxial window are connected by a chi-yoke coupling, and the tip of the coaxial inner conductor is in contact with the end surface of the post. This is an input/output coupling device having a coaxial waveguide conversion section, characterized in that the post disk is fixed to the waveguide wall by adhesive bonding using a method such as soldering, and the post disk is tightened and fixed to the wall of the waveguide with screws.

Hereinafter, the present invention will be specifically explained using examples. FIG. 3 is a diagram showing one embodiment of the present invention, in which a post 8 is inserted into the waveguide 2, and the post 8 is inserted into the waveguide 2.
A hole 9 is made in the hole 9 through which the coaxial inner conductor 4 extending from the coaxial window 1 passes. Coaxial inner conductor 4 is post 8
It penetrates through the hole 9 and is connected and fixed to the center of a thin metal disk 14 made of copper or the like having high thermal conductivity, which is in contact with the end surface of the post 8 by a method such as soldering.
The post 8 and the disk 14 are fastened and fixed to the wall of the waveguide 2 with screws 15. By selecting the length l ₁ of the hole 9 of the post 8 and the length l ₂ to the disk 14 to be a quarter wavelength, the coaxial inner conductor 4 and the post 8 are connected by a chi-yoke coupling.

With such a configuration, the coaxial inner conductor 4 is connected to the disk 1
4 and post 8 to the waveguide 2, the thermal resistance between the coaxial inner conductor and the waveguide is small. Therefore, the heat from the coaxial inner conductor is sufficiently dissipated into the waveguide, and the temperature of the coaxial inner conductor does not become too high, which prevents cracking of the ceramic plate due to the temperature rise of the coaxial inner conductor, oxidation of the coaxial inner conductor, and high frequency. No problems such as discharge occur. Also post,
The disk and waveguide walls are in contact with each other on their annular surfaces and are tightly tightened with screws, so the contact is good and problems such as high frequency leakage and heat generation due to poor contact do not occur. Furthermore, the elongation due to thermal expansion of the coaxial inner conductor is absorbed by the deformation of the thin metal disk, so no force is applied to the ceramic plate.

As is clear from the above explanation, according to the present invention, a novel input/output coupling device is obtained that can perform broadband impedance matching and sufficiently dissipate heat from the coaxial conductor, and is capable of achieving broadband impedance matching in a helical traveling wave tube. This greatly contributes to the development of higher power and higher output.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing a conventional input/output coupling device. FIG. 3 is a sectional view showing an embodiment of the present invention. 1... Coaxial window, 2... Waveguide, 3... Helix, 4... Coaxial inner conductor, 5... Coaxial outer conductor, 6...
...ceramic plate, 8...post, 11...circular tube,
13...metal plate, 14...metal disc, 15...
screw.

Claims (1)

[Scope of utility model registration request] The post inserted into the waveguide and the coaxial inner conductor extended from the coaxial window are connected by a chi-yoke coupling, and the above-mentioned
A coaxial waveguide in which the tip of the coaxial inner conductor is adhesively fixed to the center of a thin metal disk that is in contact with the end surface of the post, and the post and disk are fixed to the waveguide wall by tightening screws. A traveling wave tube input/output coupling device with a converter.