JPS61281434A - Output structure of magnetron - Google Patents

Abstract

PURPOSE:To attenuate and eliminate the fifth higher harmonic efficiently by securing a tubular choke having flange section to the inside of metal seal arranged at the output section side of magnetron body while surrounding an antenna. CONSTITUTION:A tubular choke 10 integrated with tubular section 10a and flange section 10b is secured to the inside step section of metal seal 1 sealed air-tightly at the output section side of magnetron body while surrounding an antenna 7 and directing the tubular section 10a toward a tubular ceramic body 4 arranged above. When the inner diameter at the open tip side of seal 1 is about 14mm, the choke 10 is provided with the inner diameter of 9-10mm and the height H of 4.0-5.5mm while the dimension L between the ceramic body 4 is set within + or -1mm. Consequently, the fifth higher harmonic can be attenuated efficiently and the output efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetron output structure, and more particularly to a filter structure for suppressing leakage of specific strong noise radio waves such as harmonics generated from a magnetron.

[Background of the invention]

High-frequency devices such as microwave ovens are required to suppress leakage of noise radio waves to a level below a specified value in order to eliminate interference with wireless communications.

However, recent advances in communication technology have made it possible to communicate with much less power, and there has been a movement to further tighten regulations on noise levels.

On the other hand, during operation of the magnetron, harmonics including the magnetron's fundamental oscillation frequency as well as VHF and UHF band waves are radiated to the outside through its input and output sections. For this reason, the magnetron has a noise of 1! radiated from its input or output section. It is equipped with a noise-cancelling filter that attenuates and eliminates waves and eliminates their influence on radio, television, wireless communications, etc. This is because suppressing noise radio waves as much as possible within the magnetron makes it easier to take measures against radio wave leakage in the entire device. In recent years, countries have been considering setting even stricter regulation values, and in some cases this has been implemented, and countermeasures against radio wave leakage have become an inevitable issue even for magnetrons alone.

This type of filter generally has a filter structure in which a choke coil and a feedthrough capacitor are combined and connected to the input side terminal of the magnetron, and multiple chokes are connected to the output side antenna of the magnetron. Individual filter structures are known.

Note that a filter structure in which a plurality of channels are provided on the output side of the magnetron is disclosed in, for example, Japanese Utility Model Application Publication No. 54-125564.
It is described in detail in Japanese Utility Model Application Publication No. 58-910, etc.

FIG. 5 is a sectional view of a main part showing the output structure of a nine-magnetron equipped with this type of filter structure. In the figure, 1 is a metal seal hermetically sealed to the input side of the magnetron main body which has a known internal structure and outputs high-frequency energy, and 2 is a metal output ring bonded to the outer surface of the opening side of the seal 1. , 3 is a metal cylindrical choke bonded to the inner surface of the opening side of the seal 1, 4 is an insulating cylindrical ceramic body bonded to the opening end of the cylindrical choke 3, and 5 is a metal cylindrical choke bonded to the opening side inner surface of the seal 1; A metallic exhaust pipe support 6 is joined to the open end of the exhaust pipe support 5, and 6 is a metal exhaust pipe joined to the open end of the exhaust pipe support 5. Although the end of the exhaust pipe 6 is not shown, there is an antenna 7. The tip is placed on the tip by holding the tip of the tip, and the inside is hermetically sealed. In addition, antenna 1
Although not shown, the other end is joined to one of the bays arranged radially within the magnetron main body.

However, when a magnetron having such a filter structure is attached to a microwave oven and operated, the fundamental frequency (2450 MHz band) at which the magnetron oscillates and outputs changes as the load impedance changes. At this time, harmonics are also output at the same time, and the frequency and level of the harmonics change non-uniformly with respect to the fundamental wave. Furthermore, as harmonics, the second to seventh harmonics have been confirmed, but
Due to the recent development of satellite communication, fi, 11.7~12.7
Since the GHz frequency band is used, the amount of leakage of the fifth harmonic (12.25 GHz) that is output from the magnetron has become a problem. Therefore, in the conventional filter structure in which the frequency band and attenuation amount to be attenuated are set for VHF and UHF TV broadcast bands and harmonics below the 4th harmonic, the above-mentioned @5 high wave protection cannot be achieved. It was structurally impossible to achieve sufficiently large attenuation cancellation.

[Purpose of the invention]

An object of the present invention is to provide a magnetron output structure that can efficiently attenuate and eliminate the fifth harmonic of the fundamental frequency.

[Summary of the invention]

In order to achieve such an object, the present invention provides a cylindrical choke having a flange portion inside a metal seal hermetically sealed on the output side of the magnetron main body.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 1 is a sectional view of a main part of the output structure of a magnetron according to the present invention, and the same parts as in FIG. 5 are given the same reference numerals. In the figure, a cylindrical part 101 is integrally formed at one open end of a metal seal 1 that is hermetically sealed on the output side of the magnetron body, and a 7-run 9 part 10b is integrally formed at the other open end. A cylindrical chalk 10 formed in
The cylindrical portion 10m is directed toward the ceramic body 4, and the flange portion 10b is multi-jointed by silver soldering.

This choke 10 has an inner diameter D = 9 to 10 mm and a height H = 4.
．． It has a dimension shape of 0 to 5.5 nsm, and its cylindrical part 1
0. The dimension L between the tip and the ceramic body 4 is set within a range of ±1 mm, and the seven runs 9 portion 10b is inscribed and bonded to the inner stepped portion of the metal seal 1. In this case, the inner diameter of the metal seal 1 on the tip opening side is approximately 1
The inner diameter of the cylindrical ceramic body 4 is approximately 13 mm.

As a result of measuring the leakage amount of the fifth harmonic by attaching the magnetron equipped with the output structure configured in this way to a microwave oven, we found that the height H of the choke 10 was
．． 0 to 5.5 myn, as shown in Figure 3, the inner diameter of the choke 10 is Dt - 10 mm or less, and as shown in Figure 4, the tip of the choke 10 can be installed within ±1 mm. The 5th harmonic leakage amount is 90, which is the value of the conventional configuration.
It was possible to significantly reduce the d@PW to 504B PW or less. In this case, the inner diameter of the choke 10 is as small as 10 m5 or less, which is good, but if it is less than 9 mm, the antenna IK may approach or come into contact with the antenna IK, which is undesirable, so a range of 9 to 10 mm is preferable.

〔Effect of the invention〕

As explained above, according to the present invention, a cylindrical choke having 7 links is fixedly arranged inside a metal seal disposed on the output side of the magnetron body, thereby efficiently suppressing the g5 harmonic. Since the attenuation can be eliminated and the amount of leakage can be significantly reduced, a magnetron with high quality and reliability can be obtained, which is an extremely excellent effect.

Brief Explanation of Page 9 FIG. 1 is a cross-sectional view of essential parts showing an example of the output structure of a magnetron according to the present invention, FIG. 2 is a diagram showing the relationship between choke height H and fifth harmonic leakage amount, and FIG. Figure 3 is a diagram showing the relationship between the inner diameter of the choke and the amount of fifth harmonic leakage, Figure 4 is a diagram showing the relationship between the choke tip position and the amount of fifth harmonic leakage, and Figure 5 is a diagram showing the relationship between the choke's inner diameter and the amount of fifth harmonic leakage. FIG.

, 1Φ...Seal, 2---Output link, 4...
War/Ceramic body, 5...Exhaust pipe support, 6/Φ
...Exhaust pipe, 7.Bone-antenna, 10..Choke, 10a..Cylindrical part, 10b..-Fist 7 lunge part.

Figure 1 Figure 2 +Boot height H (mm) 1-F country I 10 (mm)

Claims (1)

[Scope of Claims] 1. In the output structure of a magnetron, in which a seal surrounding an antenna, a ceramic body, and an exhaust pipe are sequentially bonded to the output side of a magnetron main body that outputs high-frequency energy, and the inside is hermetically sealed. An output structure for a magnetron, characterized in that a cylindrical choke having a flange portion is fixedly arranged inside. 2. The magnetron output structure according to claim 1, wherein the height of the choke is set in a range of 4.0 to 5.5 mm. 3. The magnetron output structure according to claim 1, wherein the inner diameter of the choke is set in a range of 9 to 10 mm. 4. The magnetron output structure according to claim 1, wherein the dimension between the tip of the choke and the anode-side open end of the ceramic body is set to ±1 mm or less.