JPH0352007Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] In a microwave device using the waveguide transmission line of the present invention, the present invention relates to a load impedance adjustment device that is attached to a part of the waveguide and adjusts the load impedance.

[Background of the invention] Microwaves are already used in many technical fields, but in order to use them efficiently, it is necessary to minimize reflection from loads. For this reason, an impedance adjustment device is inserted into the transmission line to match the load. Many of the impedance adjustment devices used so far when the microwave power is relatively large are of the waveguide type. Examples of this type include 3-stub, slug tuner, and E/H tuner.
Since 3-stubs are commonly used because of their ease of handling and operation, the prior art will be explained here by taking 3-stubs as an example.

FIG. 9 shows a conventionally used three-stub. In the figure, 1 is a waveguide, 2 is a flange, and 3 is (n/2+1/4)λg or (n/2+1/2)
8) Stubs provided at λg intervals. If the load is not matched, each stub is inserted at the maximum electric field point within the waveguide (the midpoint of the long side in a rectangular waveguide) to match the load.

The required insertion depth varies depending on the load impedance, and the insertion depth tends to be deeper for low and high impedances. As the depth increases, the electric field of the stub increases, so the microwave withstand voltage becomes lower than that of a hollow waveguide with nothing inside, and the microwave power that can be used as a whole is limited by the withstand voltage of the 3-stub. It has the disadvantage of being rejected.

[Purpose of invention]

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and specifically, to provide a microwave load impedance adjustment device that can be used up to the same withstand voltage as a hollow waveguide.

[Summary of the idea]

The present invention configures a load impedance adjustment device by combining an inductive window and a plurality of phase waveguides of different lengths, eliminates elements that reduce withstand voltage, and
This ensures the same microwave resistance as a hollow waveguide.

[Example of idea]

Next, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 8.

In FIG. 1 showing an example of the load impedance adjustment device according to the present invention, 4 is an inductive window;
6 and 7 are respectively, when the tube wavelength is λg,
It is a flanged hollow waveguide with lengths of λg/16, 8/λg, and λg/4. Here, the hollow waveguides 5, 6, and 7 that adjust the load impedance in combination with the inductive window 4 will be referred to as phase waveguides.

The inductive window 4 is designed to adjust the susceptance by changing the H plane dimension, that is, the long side dimension a of the waveguide opening, without changing the E plane dimension, that is, the short side dimension b of the waveguide opening. , the microwave breakdown voltage is the same as that of a hollow waveguide.

An adjustment method for changing the phase of susceptance will be described next. The already mentioned FIG. 1 shows the inductive window 4.
The case where is placed on the phase reference plane is shown. Figure 2 shows that when the phase is changed by λg/16 with respect to the phase reference plane, similarly, Figure 3 is λg/8, Figure 4 is 3λg/16, Figure 5 is λg/4, and Figure 6 is is 5λg/16, Fig. 7 is 3λg/8, 8th
The figures each show the case where the phase is changed by 7λg/16. In this way, the phase changes depending on where the inductive window is inserted. The advantage of this example is that when combining an inductive window and a phase waveguide,
One advantage is that the load impedance can be adjusted in stages by dividing λg/3 into eight equal parts without changing the overall length L.

In this embodiment, the case of three divisions has been described, but if the number of divisions is further increased, the load impedance can be adjusted finer. Further, if a plurality of inductive windows of the same thickness and different susceptances are prepared, the impedance adjustment range becomes wider.

(1) Instead of the conventional method of inserting a stub etc. at the maximum electric field point in the waveguide, an inductive window is used to change the susceptance, so the microwave breakdown voltage is the same as that of a hollow waveguide. Become.

(2) In this example, since it was explained that λg/2 is divided into 8 and the impedance is adjusted stepwise, it gives the impression that the impedance adjustment range is narrow compared to something that changes continuously like a stub. However, by increasing the division of the phase waveguide, a practically acceptable adjustment range can be secured.

(3) Since the total length L is constant, the impedance can be adjusted while the three-dimensional circuit system to be connected remains fixed.

(4) 8 types for waveguide division number 3, 16 types for 4, m
This means that many types of phase adjustments can be made with a limited number of divisions, such as 2 ^m types.

[Effect of idea]

According to the present invention, the microwave breakdown voltage is the same as that of a hollow waveguide, and it is possible to obtain a load impedance adjustment device for a high-output microwave device, such as a continuous magnetron oscillator with an output of 500 KW, which was extremely difficult with conventional methods. .

[Brief explanation of the drawing]

Figure 1 is a diagram showing the basic configuration of the load impedance adjustment device of the present invention, Figures 2 to 8 are diagrams explaining the situation in which the impedance is adjusted by changing the position of the inductive window, and Figure 9 is the conventional one. It is a figure showing 3-stub of. 1... Waveguide, 2... Flange, 3... Stub, 4... Inductive window, 5... λg/16 length waveguide, 6... λg/8 length waveguide, 7... ...λg/4 length waveguide.

Claims (1)

[Claims for Utility Model Registration] In a load impedance adjustment device that is inserted into a microwave transmission line to match the load, an inductive window and a device having different lengths (meters) are used to change the phase of the microwave.
The lengths ₁ , ₂ , ..., _n of the hollow waveguides in the tube axis direction are ₁ = 1/2 (1/2 ^m + n ₁ ) λg ₂ = 2 /1 (1/2 ^m-1 +n ₂ ) λg …………… _n-1 = 1/2 (1/4 + n _n-1 ) λg _n = 1/2 (1/2 + n _n ) λg m, n ₁ , n ₂ , ...n _n : Any positive integer λg: A load impedance adjustment device characterized in that it is a tube wavelength.