JPH08154001A - Pillbox type vacuum window - Google Patents

Abstract

PURPOSE: To facilitate the miniaturization of a microwave tube by simplifying complicated design by providing the compactly and simply structured pillbox type vacuum window which unnecessitates the installation of a matching transformer and can shorten the length of a waveguide. CONSTITUTION: A dielectric disk 17 mode of alumina ceramic or the like is provided at the central part of a circular waveguide 18, and this dielectric disk 17 is mounted onto a circular waveguide 18 with the practically same inner diameter as the outer diameter of this dielectric disk 17 by brazing, etc. Two rectangular waveguides 12 and 13, for which the length of one of long side and short side is made different at least, are joined at both the ends of this circular waveguide 18 by brazing or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pillbox type vacuum window, and more particularly to a pillbox type vacuum window used as an input / output window of a microwave tube.

[0002]

2. Description of the Related Art Microwave power has been widely applied to TV broadcasting, line-of-sight communication, non-line-of-sight communication, satellite communication, space communication, radar, microwave heating, etc., and microwaves used in these microwave bands. Wave tubes include traveling wave tubes, klystrons, magnetrons, and the like. The microwave tube mainly includes a traveling wave tube and a clastron.
The optimum one is selected from these microwave tubes according to the microwave power level, but in the fields of broadcasting and communication, traveling wave tubes and klystrons are mainly used as the final stage amplification tubes of transmitters. . The demands for higher performance of these microwave tubes are increasing year by year, and there is a trend toward higher frequency, wider bandwidth, higher output, smaller size, and higher stable operation. In a high frequency and high power microwave tube, there is an increased risk of breakage due to abnormal operation due to finer dimensions due to higher frequency and increase in voltage and current due to higher output.

Next, the structure of a conventional microwave tube will be described with reference to an example of a helix type traveling wave tube provided with a helix type slow wave circuit which is one of linear beam microwave tubes.

FIG. 8 is a sectional view showing an example of the structure of a conventional helix type traveling wave tube. As shown in FIG. 8, the conventional linear beam microwave tube mainly includes an electron gun unit 1 that generates an electron beam and a delay unit that amplifies the input microwave by the interaction between the electron beam emitted from the electron gun unit 1 and an input signal. The wave circuit unit 2 and the collector unit 3 which captures the electron beam transmitted through the slow wave circuit unit 2 and converts the electron beam into heat energy. Further, a focusing magnetic field device unit for focusing the electron beam emitted from the electron gun unit 1 outside the slow wave circuit unit 2 and generating a magnetic field for passing through the slow wave circuit unit 2 with a substantially constant beam diameter. 4 are provided. Further, it is composed of a microwave input section 5 for inputting microwave power, a microwave output section 6 for extracting amplified microwave power, and a case 7 for fixing the above members.

FIG. 9 is a sectional view showing an example of the structure of a microwave output section of a conventional linear beam microwave tube. Figure 9
As shown in FIG. 3, in the conventional microwave output unit 6, the antenna 9 is welded to the end of the helix 8 that interacts with the electron beam in the slow wave circuit unit 2, and the TEM transmitted from this antenna 9 is transmitted. The high-frequency power of the mode is converted into the TE mode which is the transmission mode of the rectangular waveguide by the coaxial waveguide converter 10, and reaches the pill box type vacuum window 11 for vacuum-sealing the linear beam microwave tube. The high-frequency power of TE mode is transmitted from the rectangular waveguide 13 having the same shape as the rectangular waveguide 12 on the opposite side. After this, by the step or taper waveguide 14, it is transmitted to the rectangular waveguide 15 that has a low loss within the used frequency, that is, is larger than the rectangular waveguide 12 described above. Then, it is connected to the device side via the flange 16.

10 (a) and 10 (b) are a longitudinal sectional view and a lateral sectional view showing an example of the structure of a conventional pill box type vacuum window. There is a dielectric disk 17 made of alumina ceramics or the like in the central portion thereof, and the dielectric disk 17 is mounted on a circular waveguide 18 having substantially the same inner diameter as the dielectric disk 17 by brazing or the like, The circular waveguide 18
Rectangular waveguides 12 and 13 are joined to both ends of the by means of brazing or the like.

FIG. 11 shows an example of the pill box type vacuum window of FIG. 10 at 14 GHz by computer simulation.
It is a characteristic view which shows the frequency characteristic of the constant voltage standing wave ratio of a band.
The length of each part is the long side a = 15, 8 m of the rectangular waveguide 13.
m, short side b = 7.9, inner radius of cylindrical waveguide 18 R = 9 m
m, the thickness d of the dielectric disk 17 made of alumina ceramics
= 0.6 mm, end face of cylindrical waveguide 18 and dielectric disk 17
The distance S is 3 mm, and the simulation result is obtained when the relative permittivity ε of the alumina ceramic dielectric disk 17 is 9.2. As shown in FIG. 11, in the conventional pill box type vacuum window, 11 to 12 GH
Constant voltage standing wave ratio of 1.2 or less in the range of z (hereinafter, VSW
The frequency characteristic of R) is obtained.

Next, a conventional pillbox type vacuum window will be described with reference to a cited example.

12 (a) and 12 (b) are a longitudinal sectional view and a lateral sectional view, respectively, showing the construction of a reference 1 of a conventional pillbox type vacuum window. Cited example 1 is a pill box type vacuum window disclosed in Japanese Patent Application Laid-Open No. 4-92341, which is shown in FIG.
As shown in (b), the long sides a and the short sides b of the rectangular waveguides 12 and 13 forming the pillbox type vacuum window have the same dimensions, and the long side a and the inner radius R of the circular waveguide 18 are equal to each other. Between R
It is characterized by the existence of the relationship <a / 2. With such a structure, a very wide-band pillbox-type vacuum window can be obtained, and by using this pillbox-type vacuum window as an input / output window of a microwave tube, an extremely wide-band microwave tube can be obtained. It is a thing.

FIGS. 13 (a) and 13 (b) are a longitudinal sectional view and a lateral sectional view showing the structure of a reference 2 of a conventional pillbox type vacuum window. Citation example 2 is a pill box type vacuum window disclosed in Japanese Patent Laid-Open No. 3-145201, and is shown in FIG.
As shown in (a) and (b), a pillbox type vacuum window is formed by connecting the rectangular waveguides 12 and 13 including the matching transformers at both ends of the circular waveguide 18. I am trying. With this configuration, it is possible to operate in a wide frequency band without the ghost mode. Also, the mechanical properties are improved and their dimensions are reduced.

[0011]

In the conventional microwave tube using the pill box type vacuum window, the apparatus using the microwave tube usually has a large shape with the lowest loss even in the operating frequency. A rectangular waveguide is used. For this reason, in the conventional pillbox type vacuum window, a method of making the rectangular waveguides at both ends of the circular waveguide the same size as the device, or providing a step or taper waveguide on the device side The shape of the rectangular waveguide was matched. However, due to recent demands for downsizing and cost reduction of devices, steps and tapered waveguides are not provided on the device side.
In addition, in order to reduce the vacuum capacity of the microwave tube, the dimensions of the rectangular waveguide up to the pillbox-type vacuum window should be as small as possible within the operating frequency. A taper waveguide or a step waveguide, which is a kind of matching transformer, is used on the side to expand the size to the size desired on the device side. This is because, as shown in the reference example 1, in the conventional pill box type vacuum window, the rectangular waveguides at both ends of the circular waveguide have the same shape. The reason for using the same shape is that the impedance of the rectangular waveguide is the same, which facilitates the calculation when designing a pillbox-type vacuum window and that a good VSWR frequency characteristic is obtained in the frequency band used. It was because it was thought that it would be. However, the above-mentioned means has a complicated structure, and in order to provide the matching transformer, the rectangular waveguide needs to have a length corresponding to at least a half wavelength of the used frequency.

It is an object of the present invention to provide a pillbox type vacuum window which is compact and has a simple structure, because it is not necessary to provide a matching transformer, and the length of the rectangular waveguide can be shortened.

[0013]

A pill box type vacuum window of the first invention is a dielectric disk and a dielectric disk including the dielectric disk and having an inner diameter substantially the same as the diameter of the dielectric disk and having the dielectric film at the center. A pillbox-type vacuum window having a circular waveguide on which a body disk is mounted and two rectangular waveguides connected to both ends of the circular waveguide, wherein long sides of the two rectangular waveguides are provided. And at least one of the short sides of each is different in length. In this pillbox type vacuum window, the inner diameter of the circular waveguide is smaller than the length of the diagonal of the rectangular waveguide connected to one end of this circular waveguide, and the rectangular waveguide connected to the other end It is configured to be larger than the length of the diagonal line.

The pillbox type vacuum window of the second invention is a circular disk having a dielectric disk and an outer diameter smaller than the diameter of the dielectric disk and having the dielectric disk mounted in the center thereof. Waveguide and 2 connected to both ends of this circular waveguide
In a pillbox-type vacuum window having two rectangular waveguides, the length of at least one of the long sides of the two rectangular waveguides and the short sides of the two rectangular waveguides. Are different. In this pillbox type vacuum window, the inner diameter of the circular waveguide is smaller than the length of the diagonal of the rectangular waveguide connected to one end of this circular waveguide, and the rectangular waveguide connected to the other end It is configured to be larger than the length of the diagonal line.

[0015]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a sectional view showing a structure of a microwave output section of a microwave tube using the first embodiment of the present invention. As shown in FIG. 1, in the microwave output unit using the first embodiment of the present invention, an antenna 9 is welded to an end of a helix 8 that interacts with an electron beam in a slow wave circuit unit 2. The high frequency power of the TEM mode transmitted from the antenna 9 is converted into the TE mode which is the transmission mode of the rectangular waveguide by the coaxial waveguide converter 10 to vacuum seal the linear beam microwave tube. The high-frequency power of TE mode is transmitted from the rectangular waveguide 13 having a larger shape than the rectangular waveguide 12 on the opposite side. After this, the device is connected via the flange 16. In this embodiment, the length of the diagonal line of the rectangular waveguide 12 is smaller than the inner diameter of the circular waveguide 18, and the length of the diagonal line of the rectangular waveguide 13 is the circular waveguide 18.
The size is larger than the inner diameter of.

2A and 2B are a longitudinal sectional view and a lateral sectional view of the first embodiment of the present invention. In the first embodiment of the present invention, as shown in FIGS. 2 (a) and 2 (b), a dielectric disk 17 made of alumina ceramics or the like is provided in the central portion thereof, and the dielectric disk 17 is substantially It is mounted on a circular waveguide 18 having the same inner diameter as that of the dielectric disk 17 by brazing or the like, and rectangular waveguides 12 and 13 having different shapes are joined to both ends of the circular waveguide 18 by brazing or the like. ing. In addition, these rectangular waveguides 12 and 13 are EI
In the AJ standard, the ones having overlapping frequency ranges are used.

FIG. 3 is a characteristic diagram showing the frequency characteristic of the VSWR in the 14 GHz band by computer simulation according to the first embodiment of the present invention. Long side a1 = 15.8 mm, short side b1 = 7.9 mm of one rectangular waveguide 12, long side a2 = 19.05 mm, short side b2 = 9.525 mm, circular guide of the other rectangular waveguide 13. Inner radius of the wave tube 18 R = 9
mm, thickness of dielectric band disk 17 made of alumina ceramics d = 0.6 mm, relative permittivity ε = 9.2, and circular waveguide 1
The distance s = 3 mm between the end face of 8 and the dielectric disk 17,
The dimensions a1 and b1 in this case are 14 GHz, which is the operating frequency.
Rectangular waveguide 12 having a shape as small as possible in the z band
And the dimensions a2 and b2 are the operating frequency of 14 GHz.
Large rectangular waveguide with the lowest loss in the band 1
It is 3. FIG. 3 shows the result obtained by the simulation at this time. As shown in FIG. 3, the frequency characteristic of VSWR of the conventional pillbox type vacuum window shown in FIG. Was confirmed. That is, the rectangular waveguide 12 in which the frequencies used overlap,
It was found that in No. 13, the difference in characteristic impedance was small and the influence on the pillbox type vacuum window was small and could be ignored.

FIG. 4 is a sectional view showing the structure of a linear beam microwave tube using the first embodiment of the present invention. The overall structure of the linear beam microwave tube of the first embodiment is shown in FIG.
As shown in FIG. 1, an electron gun unit 1 for generating an electron beam, a slow wave circuit unit 2 for amplifying an input microwave by interaction between an electron beam emitted from the electron gun unit and an input signal, and this slow wave circuit unit 2 It is composed of a collector portion 3 for accelerating the electron beam that has passed through and converting it into heat energy. Further, a focusing magnetic field device unit for focusing the electron beam emitted from the electron gun unit 1 outside the slow wave circuit unit 2 and generating a magnetic field for passing through the slow wave circuit unit 2 with a substantially constant beam diameter. 4 are provided. Further, a microwave input unit 5 for inputting microwave power, a microwave output unit 6 for extracting amplified microwave power, and a case 7 for fixing the above members are provided, and a linear beam microwave tube is provided. Is configured to work as. In this embodiment, the structure example of the helix type traveling wave tube is given as one of the microwave tubes, but it can be applied to other microwave tubes such as a coupled cavity type traveling wave tube and a klystron.

5 (a) and 5 (b) are a longitudinal sectional view and a lateral sectional view showing the configuration of the second embodiment of the present invention. The second embodiment of the present invention, as shown in FIGS.
A dielectric disc 17 made of alumina ceramics or the like is sandwiched by a circular waveguide 18 having an outer diameter smaller than the diameter of the dielectric disc 17, and rectangular waveguides 12 at both ends are provided.
At least one of the long sides or the short sides of 13 is different. Since this structure is sealed by the disk surface of the dielectric disk 17, a large sealing area can be obtained.
There is an advantage that it can be made stronger in strength as compared with the embodiment of.
In other words, this structure is adopted in a pillbox type vacuum window that is normally used at a frequency of 14 GHz band or higher.

6 (a) and 6 (b) are a longitudinal sectional view and a lateral sectional view showing the structure of the third embodiment of the present invention. The third embodiment of the present invention, as shown in FIGS. 6 (a) and 6 (b),
There is a dielectric disk 17 made of alumina ceramics or the like in the central portion thereof, and the dielectric disk 17 is mounted on a circular waveguide 18 having substantially the same inner diameter as the dielectric disk 17 by brazing or the like, Rectangular waveguides 12 and 13 having different shapes are joined to both ends of the circular waveguide 18 by brazing or the like. At this time, the rectangular waveguide on the vacuum side is
The IAJ standard has a small shape, and the outside of the vacuum is a rectangular waveguide having a large shape in consideration of improvement of RF withstand voltage.

FIG. 7 is a characteristic diagram showing the frequency characteristic of VSWR by computer simulation according to the third embodiment of the present invention. The frequency characteristic of VSWR in this case is shown in FIG.
As shown in FIG. 3, although the good frequency characteristics of VSWR are narrowed, the pill box type vacuum window of this embodiment is resistant to RF outside of vacuum when it is used in a high-power microwave tube for energy with a fixed working frequency. There is an advantage that the microwave tube with high voltage can be miniaturized.

[0023]

As described above, the present invention includes a dielectric disk made of alumina ceramics or the like in the central portion thereof, and the dielectric disk has an inner diameter substantially equal to or smaller than the diameter of the dielectric disk. Two rectangular waveguides which are mounted on a circular waveguide having a diameter by brazing or the like and have at least one of the long side and the short side having different lengths at both ends. By joining the two by brazing or the like, there is no need to provide a matching transformer, and the length of each rectangular waveguide can be shortened, so that there is an effect that a pill box type vacuum window having a small and simple structure can be provided.

Further, by removing the matching transformer of the rectangular waveguide which has an influence on the frequency characteristic of the VSWR, the complicated design can be facilitated and the miniaturization of the microwave tube can be facilitated.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a microwave output section of a microwave tube using a first embodiment of the present invention.

2 (a) and 2 (b) are a longitudinal sectional view and a lateral sectional view showing a configuration of a first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing frequency characteristics of a 14 GHz band VSWR obtained by computer simulation according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of a linear beam microwave tube using the first embodiment of the present invention.

5 (a) and 5 (b) are a longitudinal sectional view and a lateral sectional view showing a configuration of a second embodiment of the present invention.

6 (a) and 6 (b) are a longitudinal sectional view and a lateral sectional view showing a configuration of a third embodiment of the present invention.

FIG. 7 is a characteristic diagram showing a frequency characteristic of VSWR by computer simulation according to a third embodiment of the present invention.

FIG. 8 is a cross-sectional view showing an example of the configuration of a conventional helix type traveling wave tube.

FIG. 9 is a cross-sectional view showing an example of the configuration of a microwave output section of a conventional linear beam microwave tube.

10 (a) and 10 (b) are a longitudinal sectional view and a lateral sectional view showing an example of the configuration of a conventional pill box type vacuum window.

11 is a characteristic diagram showing frequency characteristics of a constant voltage standing wave ratio in a 14 GHz band by computer simulation of an example of the pill box type vacuum window of FIG.

12 (a) and 12 (b) are a longitudinal sectional view and a lateral sectional view showing a configuration of a reference example 1 of a conventional pill box type vacuum window.

13 (a) and 13 (b) are a longitudinal sectional view and a lateral sectional view showing a configuration of a conventional pillbox-type vacuum window according to a second reference example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun section 2 Slow wave circuit section 3 Collector section 4 Focusing magnetic field apparatus section 5 Microwave input section 6 Microwave output section 7 Case 8 Helix 9 Antenna 10 Coaxial waveguide converter 11 Pilbox type vacuum window 12 Tip rectangle Waveguide 13 Rectangular Waveguide 14 Step or Tapered Waveguide 15 Large Rectangular Waveguide 16 Flange 17 Dielectric Disc 18 Circular Waveguide

Claims (4)

[Claims] 1. A dielectric disc, a circular waveguide including the dielectric disc, having an inner diameter substantially the same as the diameter of the dielectric disc, and mounting the dielectric disc at the center thereof, and the circular waveguide. A pillbox-type vacuum window having two rectangular waveguides connected to both ends of the two rectangular waveguides, at least one of the lengths of the long sides and the lengths of the short sides of the two rectangular waveguides. Pillbox type vacuum window characterized by different lengths on one side. 2. The pill box type vacuum window according to claim 1, wherein the inner diameter of the circular waveguide is smaller than the length of the diagonal line of the rectangular waveguide connected to one end of the circular waveguide, and the other end. A pillbox-type vacuum window, characterized in that it is larger than the length of the diagonal of the rectangular waveguide connected to. 3. A dielectric disk, a circular waveguide including the dielectric disk and having the outer diameter smaller than the diameter of the dielectric disk and having the dielectric disk mounted at the center thereof, and the circular waveguide. A pillbox-type vacuum window having two rectangular waveguides connected to both ends thereof, wherein at least one of the long sides of the two rectangular waveguides and the short sides of the two rectangular waveguides is used. Pillbox type vacuum window characterized by different lengths on one side. 4. The pill-box type vacuum window according to claim 3, wherein the inner diameter of the circular waveguide is smaller than the length of the diagonal line of the rectangular waveguide connected to one end of the circular waveguide, and the other end. A pillbox-type vacuum window, characterized in that it is larger than the length of the diagonal of the rectangular waveguide connected to.