JPH0538522Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to microwave tubes, and in particular to improvements in high-frequency input/output circuits for microwave tubes with operating center frequencies of 14 GHz or higher.

[Conventional technology]

A microwave tube (traveling wave tube or klystron), which has been conventionally used for power amplification with an operating center frequency of 14 GHz or higher, has an electron gun section 1 that emits and forms an electron beam, and an electron gun section 1 that emits and forms an electron beam, as shown in Figure 3. A high-frequency circuit section 2 that interacts and performs an amplification action, a collector section 3 that collects the electron beam after the interaction and converts its kinetic energy into thermal energy, and supplies high-frequency power to the high-frequency circuit section 2. A high frequency input circuit 4 made up of a waveguide, a high frequency output circuit 5 made up of a waveguide that takes out the amplified electromagnetic waves from the high frequency circuit section 2, and although not shown in the figure, the repulsion between electrons It consists of a focusing circuit section that suppresses beam expansion.

The high-frequency input circuit can be constructed with a coaxial line, but in the case of a microwave tube with an operating frequency of 14 GHz or higher, increasing the diameter of the coaxial line may cause the generation of undesirable propagation modes during electromagnetic wave propagation. , it is usually necessary to use a coaxial line of 3.5 mm or less. The part where such a coaxial line is connected to the high-frequency circuit section is composed of a loop-shaped conductor, but since slight differences in the mechanical dimensions have a large effect on the characteristics of the microwave tube, it is usually a waveguide. A high frequency input circuit is constructed by:

On the other hand, in order to propagate the amplified electromagnetic waves of the microwave body, high-frequency output circuits require the use of a waveguide with a large permissible power. Waveguides have been used as high-frequency output circuits.

These high-frequency input circuits and high-frequency output circuits are taken out in the same direction in order to efficiently arrange the three-dimensional circuit connected to the microwave tube, and the waveguide flange surface of the high-frequency input circuit and the flange surface of the high-frequency output circuit were placed on the same plane.

[Problem that the invention attempts to solve]

In such microwave tubes, if the waveguide flange surface of the high frequency input circuit or output circuit is scratched or bent, or
If the tightening force of the flange was weak, electromagnetic waves could leak and affect other circuits. The leakage of electromagnetic waves is greater for microwave tubes with higher operating frequencies or microwave tubes with greater high-frequency output.Also, as the operating frequency of the microwave tube increases, the total length of the high-frequency circuit section of the microwave tube becomes shorter, so the distance between the two flanges is tends to be closer. Therefore, in severe cases, a portion of the electromagnetic waves leaking from the high-frequency output circuit propagated to the high-frequency input circuit and was amplified by the microwave tube, causing self-oscillation of the microwave tube. That is, since the microwave tube has a feedback circuit, oscillation could occur if conditions were satisfied depending on the level and phase of the feedback power and the gain of the microwave tube.

In contrast to the above-mentioned microwave tube, the microwave tube of the present invention has an originality in that the flange surfaces of the high frequency input circuit and the high frequency output circuit are not arranged on the same plane.

[Means for solving problems]

In the microwave tube of the present invention, the distance from the electron beam axis of the microwave tube to the flange surface of the high-frequency input circuit waveguide and the distance from the electron beam axis to the flange surface of the high-frequency output circuit waveguide are at least micro The operating center frequency of the wave tube differs by more than 1/2 of the free space wavelength of the electromagnetic wave.

[Embodiment 1] FIG. 1 is a front view showing an embodiment of the present invention. The electron gun section 1 injects and forms an electron beam, and the high frequency circuit section 2 causes the electron beam and electromagnetic waves incident from the high frequency input circuit 4 to interact with each other. The high frequency input circuit 4 is hermetically sealed to the high frequency circuit section 2, and is made of a waveguide having a rectangular cross section, and a flange 6 is joined to the end surface of the waveguide. A high frequency output circuit 5 for guiding the electron beam and the electromagnetic waves amplified by the high frequency circuit section 2 from a microwave tube is hermetically sealed in the downstream direction of the electron beam of the high frequency circuit section 2, and a flange 7 is joined to the end surface of the high frequency output circuit 5. . A collector section 3 for collecting the electron beam is fixed to the high frequency circuit section 2 at the most downstream side of the electron beam. The length of the waveguide of the high-frequency input circuit 4 is adjusted so that the flange 6 of the high-frequency input circuit 4 is arranged closer to the electron beam axis than the flange 7 of the high-frequency output circuit 5. It is shorter than the length of the circuit waveguide.

[Embodiment 2] FIG. 2 is a front view showing another embodiment of the present invention. In this embodiment, the flange 6 of the high frequency input circuit 4 is located farther from the electron beam axis than the flange 7 of the high frequency output circuit 5. This embodiment has the advantage that since the length of the waveguide of the high frequency output circuit 5 can be shortened, the loss of electromagnetic waves due to this portion can be reduced and heat generation can be suppressed.

[Effect of idea]

As explained above, the present invention reduces the distance between the two flanges by making the distances from the electron beam axis of the flange surface of the high-frequency input circuit and the flange surface of the high-frequency output circuit of the microwave tube different from each other. It can be made large. This results in
Even if electromagnetic waves leak from one flange, the electromagnetic waves will attenuate as they propagate through the air, and when they reach the other flange surface, the power level can be sufficiently reduced, forming a feedback circuit as a microwave tube. Stable operation can be obtained without any This invention is particularly effective for microwave tubes with high output levels and high operating frequencies. It was confirmed that leakage of electromagnetic waves has almost no effect when the distance is more than 1/2 of the free space wavelength of

[Brief explanation of drawings]

Figure 1 is a front view of the microwave tube of the present invention, and Figure 2 is a front view of the microwave tube of the present invention.
The figure is a front view of a microwave tube showing another embodiment of the present invention, and FIG. 3 is a front view of a conventional microwave tube. 1... Electron gun section, 2... High frequency circuit section, 3...
Collector section, 4... High frequency input circuit, 5... High frequency output circuit, 6, 7... Flange.

Claims (1)

[Scope of utility model registration request] In a microwave tube in which a high frequency input circuit and an output circuit are constituted by waveguides, and the two waveguides extend in the same direction from the axis of the electron beam of the microwave tube, and the operating center frequency is 14 GHz or more, The distance from the axis to the flange surface of the input circuit waveguide and the distance from the axis to the flange surface of the output circuit waveguide differ by at least 1/2 or more of the free space wavelength of the electromagnetic wave at the operating center frequency. A microwave tube featuring: