JPS6366914A - Magnetron filter - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetron filter device, and particularly to the structure of a feedthrough capacitor that constitutes the filter.

[Conventional technology]

Conventionally, as shown in Japanese Unexamined Patent Publication No. 60-243941, a feedthrough capacitor has a capacitor electrode plate provided on the end face of a generally ring-shaped dielectric, and a choke structure has been provided directly on the center conductor. be. This configuration requires a large number of parts, and no consideration was given to manufacturing costs.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take manufacturing cost into consideration, and has a problem in that the manufacturing cost of the magnetron is high.

An object of the present invention is to construct a feedthrough capacitor at low cost and to suppress microwave leakage from a magnetron.

(Means for Solving the Problems) The above object is to form a capacitor by arranging electrodes on its center conductor and the outer circumferential surface of a dielectric surrounding the center conductor, and This is achieved by forming a choke structure with a surface electrode and a metal cylinder surrounding the electrode to prevent leakage of unnecessary radiated microwaves.

[Effect]

The capacitance of the feedthrough capacitor according to the present invention can be easily set by changing the ratio of the diameters of the center conductor and the cylindrical electrode provided on the outer periphery of the dielectric, the length of the electrode, and even the material of the dielectric itself. It is possible.

In addition, the electrode and the metal cylinder surrounding it form a choke structure having a groove of approximately 1/4 wavelength of the microwave to be suppressed, and the impedance at the open end of this groove becomes maximum. Microwaves leaking from the magnetron can be eliminated and attenuated.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 denotes a central conductor that supplies a cathode current to the magnetron.A dielectric 2 surrounds the central conductor 1, and a cylindrical conductor such as a cylindrical metal body 3 is provided on the outer peripheral surface of the dielectric 2. 1 and the cylindrical metal body 3 each serve as electrodes to form a capacitor. Furthermore, a bottomed cup body 4 connected to the end of the cylindrical metal body 3 surrounds the cylindrical metal body 3 and forms a groove with two dimensions, and this Ω dimension is approximately equal to the 174 wavelength of the oscillated microwave of the magnetron. It can have a choke effect. 5 is a flange for attaching to a filter case (not shown). The one shown in Fig. 1 is filled with resin 6, which improves the insulation function from other parts, makes the entire feedthrough capacitor more robust, and allows the Ω dimension of the choke structure to be shortened according to the dielectric constant of the resin 6. Although it has the effect of
Even if the resin 6 is not filled, the insulation distance and the optimum Ω dimension can be set. As another embodiment, in the one shown in FIG. 2, the resin 6 itself has the same function as the dielectric 2 in place of the dielectric 2 shown in FIG. 1, so that the structure is simplified.

Next, as another example, the one shown in FIG. 3 has a cylindrical metal body 3 surrounded by a cup body 41 separately, and has a choke function that is superior to those shown in FIGS. 1 and 2. However, the number of parts increases accordingly.

As another example, the one shown in FIG. 4 combines the cup body 41 shown in FIG.
It has the feature that the overall length of the feedthrough capacitor can be shortened.

In the above embodiment, a cylindrical metal body is separately provided on the outer periphery of the dielectric body 2, but the metallized film may be formed by baking metal powder, or by coating the surface with a method such as thermal spraying or vapor deposition. It can also be covered.

〔Effect of the invention〕

According to the present invention, the feedthrough capacitor of a magnetron filter device has a simplified structure, which can bring about great industrial benefits such as reducing manufacturing costs and suppressing unnecessary microwave radiation.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a feedthrough capacitor according to a magnetron filter device according to the present invention, and FIGS. 2 to 4 are cross-sectional views of feedthrough capacitors according to other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Center conductor, 2... Dielectric, 3... Cylindrical metal body, 4, 41... Cup body, 5... Flange, 6...
...Resin, 42.43...Cylinder.

Claims (1)

[Claims] 1. A magnetron constructed by connecting one side of an inductance element to a cathode terminal protruding into a filter case of the magnetron, and connecting the other end to a feedthrough capacitor attached to a side surface of the filter case. In the filter device, the feedthrough capacitor includes a dielectric surrounding a center conductor and a cylindrical conductor surrounding the dielectric, forming a capacitor;
A magnetron filter device further comprising a metal body surrounding the cylindrical conductor to form a choke structure. 2. The magnetron filter device according to claim 1, wherein the feedthrough capacitor is molded with resin or the like to substantially shorten the length of the choke structure.