JPS63131437A - Magnetron - Google Patents

Abstract

PURPOSE:To suppress the leakage of noise radio waves by constituting a choke structure with a collared cylinder and a disk-shaped member. CONSTITUTION:A collared cylinder 13 arranged inside an output side sealing cylindrical member 7 is formed with a collar section 13a and a cylinder section 13b, and the cylinder section 13b is the opened end of a choke structure. The disk-shaped member 14 is provided at the predetermined position from the collared cylinder 13 on the side of the collar section 13a. The choke structure obtained by connecting this collared cylinder 13 to the output side sealing member 7 and the space constituted of the disk-shaped member 14, sealing member 7, and collar section 13a are determined in size so as to have s resonance characteristic with radio waves to be suppressed. Since resonance conditions with the frequencies to be suppressed are thus satisfied, the impedance is made high. Accordingly, the quantity of the radio raves to be blocked for emission from an antenna can be sharply decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a filter structure for suppressing leakage of specific strong noise radio waves such as harmonics generated from a magnetron.

[Conventional technology]

In conventional magnetrons, for example,
As described in Japanese Patent No. 25564, a cylindrical body is placed inside the output side metal sealing member to form a filter structure called a so-called choke structure, and the open end of the choke structure is configured to be on the anode side. was.

FIG. 3 shows an example of the output side sealing member 20.
A cylindrical body 30 for forming a choke structure is provided inside the 1
By appropriately setting the dimensions indicated by A-E in the figure,
The aim was to obtain the required filter characteristics. In particular, the dimension was set to about one quarter of the wavelength of the radio waves desired to be suppressed.

However, in this structure, only dimension A was set to about one quarter of the wavelength of the desired radio wave to be suppressed, and other dimensions were not mentioned, so the effect was small.

[Problem that the invention seeks to solve]

In the above conventional technology, a cylindrical metal tube is placed inside the output side metal sealing member to form a choke structure to form a filter structure, but regarding the space newly generated by forming the choke structure. This is because the dimensions were not taken into account.

There was a problem with improving the characteristics.

Therefore, an object of the present invention is to suppress leakage of noise radio waves more than before by improving the choke structure.

Means for Solving Problem c] Generally, a filter can be constructed by inserting a resonant circuit in the middle of a transmission line for output radio waves.

One quarter of the electrical length of the radio wave (tube wavelength)
If a choke structure is formed in the length of , the radio waves will not be able to pass through. This is because the impedance seen from the open end of the choke to the choke part is theoretically infinite for the radio wave, so the impedance seen from the open end of the coaxial part to the load side is ignored. This is because the voltage applied to the load side becomes zero.

In the above explanation, the choke structure was taken as an example, but in general, what kind of resonant circuit and how to add it to the output structure of the magnetron is important in increasing the leakage prevention effect.

The present invention provides a cylindrical body with a brim so as to circumferentially surround the antenna lead inside an output side sealing member that surrounds an antenna lead connected to a vane of a magnetron main body, and a cylindrical body with a brim that surrounds the antenna lead in a circumferential direction. A metal disc-shaped member is provided on the brim side of the body, and a space surrounded by the brim, the output-side sealing member, and the disc-shaped member, and a space surrounded by the brim cylindrical body and the output-side sealing member. The space surrounded by (chalk structure),
This is achieved by resonating the frequency of the specific radio waves that you want to block.

[Effect]

With this configuration, for the frequency that is the resonance condition,
The impedance of each space becomes large, and only the voltage divided by proportional distribution with the impedance seen from the output side is present, so that the passage (leakage) of radio waves of the specific frequency is suppressed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the figure, 1 is a cylindrical anode, 2 is a vane fixed radially inside the anode, and 3 and 4 are strap rings for making every other vane the same potential. 2, 3.4 form a resonator for the anode. 5 is a cathode for emitting necessary thermoelectrons; 6 is a magnetic pole for converging the magnetic field from a permanent magnet (not shown); 7 is an output-side sealing cylindrical member, which connects the anode 1 and the output-side insulator 9; The space between them is hermetically sealed. 8 is an antenna lead that propagates the microwave energy stored in the anode resonator to the antenna;
Reference numeral 11 denotes an exhaust pipe for evacuation, into which the antenna lead 8 is pressed and cut. Reference numeral 10 denotes a sealing member of the antenna section, which hermetically seals between the output side insulator 9 and the exhaust pipe 11.

12 has the function of adjusting the height of the antenna with an antenna cap.

Reference numeral 13 designates a cylindrical body with a collar disposed inside the output-side sealing cylindrical member 7 according to the present invention, and is formed by a collar portion 13a and a cylindrical portion 13b, and the open end of the choke structure is 1
It becomes 3b. Also, 14 is a disc-shaped member with 13 on the side of 13a.
It is provided at a predetermined position from the beginning.

A choke structure obtained by connecting the above-described cylindrical body 13 to the output side sealing member 7 and a disk-shaped member 1
4 and the output-side sealing member 7 and the cylindrical collar 13a are dimensioned so as to have resonance characteristics for the radio waves to be suppressed.

According to this embodiment, since the resonance condition is satisfied for the frequency to be suppressed, the impedance becomes high, and the amount of radio waves to be blocked radiated from the antenna can be significantly reduced.

As a specific example, if the relationship between the cylindrical body 13 and the output side sealing member 7 is S=φ19m in FIG. 1, then Q=6 mm, P=6, 2 mm,
When R=φ9nn, T=φ13mm, and U=3nn, the transmission attenuation was as shown in FIG. 2. That is, when the same resonator exists separated by approximately one-fourth of the electrical length, the two resonance characteristics are added, and a large attenuation characteristic is obtained over a wider band.

Therefore, the resonance frequencies of the two spaces P and (2) may be the same or different.

In particular, when the cylindrical portion 13b is disposed on the output side and the sealing portion of the output side sealing member 7 has a smaller diameter on the output side insulator 9 side than on the anode side, the Q of the resonator inside the choke structure is
will be larger, and a greater effect can be expected.

〔Effect of the invention〕

As described in detail above, according to the present invention, the amount of transmission of radio waves of a frequency whose emission from the magnetron is desired to be suppressed can be made extremely small.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main part of an embodiment of the present invention, FIG. 2 is a characteristic diagram of the embodiment of the invention, and FIG. 3 is a sectional view of the main part of the conventional output side. 7... Output side sealing member, 8... Antenna lead, 1
3... Brim cylindrical body, 13a... Brim portion, 13b.
... Cylindrical part, 14... Disc-shaped part frequency (GHz)

Claims (1)

[Claims] 1. A magnetron in which a choke structure surrounding the antenna lead in the circumferential direction is formed inside an output-side sealing member having the same potential as the anode surrounding the antenna lead connected to the vane of the magnetron body. . A magnetron, wherein the choke structure is composed of a cylindrical body with a flange and a disc-shaped member.