JPS624815B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in magnetrons.

As shown in FIGS. 1 and 2, in the conventional magnetron main body, a plurality of plate-shaped anode vanes 12 are arranged radially to surround a central cylindrical cathode 11, and the outer ends of the vanes 12 is fixed to the anode cylinder 13. Upper and lower ends 14a of the vane 12,
14b, two integrated ring-shaped straps 15a, 15b, 15c, and 15d are connected to alternately short-circuit every other vane 12.
In case b, the size relationship of the short-circuited straps is opposite. Two adjacent vanes 12 and anode cylinder 13
A space surrounded by an inner wall and partially open toward the cathode 11 forms a cavity resonator 16 , and this cavity resonator 16 is coupled through a working space 18 between the vane tip 17 and the cathode 11 . This determines the oscillation frequency of the magnetron, and the strap separates this oscillation frequency from unnecessary modes and stabilizes it.

However, since the strap deforms the high-frequency electric field leaking from the upper and lower ends of the vane to the upper and lower end spaces 19 of the vane, a component that excites the cathode 11 in the axial direction is generated, which is a major cause of leakage of the high-frequency electromagnetic field to the input section 20 side. becomes. FIG. 3 shows the leakage electric field distribution to the end space measured on the circumference centered on the axis of the cathode 11 to show cathode excitation by the strap. Fig. 3a is a linear development of the anode and cathode structures shown in Fig. ₁ , and Figs. The distribution of the high-frequency electric field measured as it passes through R ₂ slightly outside the strap and the intermediate portion R ₃ between the anode cylinder 13 and the outside strap is shown. The vertical axis is the vane end surface 14a in the end space 19.
High-frequency electric field strength E in the direction perpendicular to , the horizontal axis is the cathode 1
This is the rotation angle P around one axis. From FIG. 3d, it can be seen that the leakage high-frequency electric field at a location away from the strap has a sign corresponding to Vane, and the amplitudes are almost equal in both positive and negative directions. However, as can be seen from Figure 3b, near the tip of the vane, the positive and negative amplitudes are greatly different. be. In such a situation, the high-frequency electric fields in the axial direction felt by the cathode 11 do not cancel each other out, and in the case of FIG. 3b, an electric field in the negative direction is felt. Up to this point, only one side end 14a of the vane 12 has been considered, but since the order of coupling of the large and small straps is also reversed at the other end 14b, the cathode 11 is excited in the same direction. The cathode 11 excited by the above mechanism radiates a high frequency electromagnetic field through the input section 20 to the filter box 21 shown in FIG. but inside the filter box 21 or
The high-frequency electromagnetic field energy reflected by the input section 20 and returned to the working space 18 may cause deterioration of magnetron characteristics such as abnormal heating of the cathode and reduction in efficiency. Therefore, countermeasures against leakage electromagnetic fields have conventionally been taken by configuring a λ/4 choke or a capacitor in the input section 20, adjusting the input side impedance as seen from the working space 18, and the like. However, such a method is difficult to predict theoretically and is carried out mainly by trial and error, resulting in a large amount of time and economic waste.In addition, the shape and position of the input section 20, filter box 21, and choke coil are greatly restricted. Therefore, the low-pass filter section has some drawbacks, such as not being able to provide a sufficient effect.

The present invention aims to eliminate this drawback by eliminating or reducing the excitation source of the cathode section.

The outline of the present invention is to reduce the cathode excitation component to zero by forming part of each of the two straps attached to the vane side end into a shape in which the inner strap and the outer strap intersect and replace each other without contacting each other. This solves the above drawbacks.

Hereinafter, based on the embodiments of the present invention shown in the drawings,
I will explain in detail.

The symbols in the figures other than the straps are the same as in the conventional example. Strap A30, Strap B3
In 1, the order in which the vanes are shorted on the left and right sides of the straight line C-C' passing through the tube axis is reversed, and at the two points that intersect with the straight line C-C', the outer strap on the right side is connected to the inner strap on the left side. , and the inner one on the right side is combined with the outer one on the left side. FIG. 5 is expanded and shown in FIG. 6a, and the distribution of the leakage high-frequency electric field to the end space 19 above the intermediate portion R1 between the inner strap and the vane tip ₁₇ is shown in FIG. 6b. As can be seen from this figure, the region where the negative part of the electric field is large and the region where the positive part is large are equal, and as a whole, the excitation part in the axial direction of the cathode 11 cancels out and becomes zero, and no excitation occurs. .

As described above, the present invention is designed to improve the end space 19 due to the straps 30 and 31, which is a major cause of excitation of the cathode 11.
The high-frequency electric field leaking to the
Therefore, the input section 20 and the filter box 21
The internal design can be done without being subject to strict regulations such as adjusting the impedance on the input section side as seen from inside the working space 18, and is also effective in improving the performance of the magnetron.

In the embodiment shown in FIG. 5, the large and small straps have two intersections, but the number of intersections can be any even number within the number of vanes. The positions where these intersect are symmetrical with respect to the tube axis. In addition, the shape of the strap at the intersection point is such that the two straps are equivalent when considering all the intersection points, that is, the number of times that strap A crosses above strap B and the number of times that the strap crosses over strap B are the same. desirable.

Other examples of strap intersections are shown in Nos. 7, 8, and 9.
As shown in the figure. Fig. 7 shows a part of both straps cut out to prevent the straps from coming into contact with each other at the intersection and reduce assembly precision, and Fig. 8 shows one strap bent in the vertical direction. , the shape is such that it avoids the other strap. or,
In FIG. 9, cuts are made at the top and bottom of the straps near the intersection, and the straps are connected through vanes, and the straps themselves do not intersect, which simplifies manufacturing.

As described above, in addition to the case where the intersection of the straps is located between the vanes, the intersection may be located on the vane, and an embodiment thereof is shown in FIG. 10.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the conventional structure, Figure 2 is its longitudinal cross-section, Figures 3 a to d are diagrams showing the distribution of the leakage electric field to the end space, and Figure 4 is a cross-sectional view including the exterior of the magnetron. , FIG. 5 is a cross-sectional view of essential parts showing one embodiment of the present invention, FIGS. 6 a and b are operational diagrams, and FIG.
8, 9, and 10 are perspective views of main parts showing other embodiments. 11... cathode, 12... vane, 14a, 14
b... Vane side end, 30, 31... A pair of straps.

Claims (1)

[Claims] 1 a central cathode, a plurality of anode vanes surrounding the cathode and arranged radially, an anode cylinder to which the outer ends of the vanes are fixed, and a plurality of anode vanes located at side ends of the vanes. In a magnetron having two pairs of ring-shaped straps connected alternately to each other, the portion where the two pairs of straps intersect between the vanes or on the vanes without contacting each other is defined as the tube axis. A magnetron characterized by having an even number of magnetrons in a symmetrical positional relationship.