JPH10224101A - Waveguide choke flange - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a choke flange of a waveguide which is smaller and lighter than those of a conventional choke flange and whose production cost is more inexpensive than a conventional choke flange. SOLUTION: In a waveguide choke flange 2, the mechanical dimension of a choke circuit is contracted by arranging a guide body 20 in a space part that forms the choke circuit. The space part that forms the choke circuit is provided as a square slender groove, that is similar to a rectangular waveguide 1, on the outside, of an opening of the rectangular waveguide 1. Further, a gap 5 of a waveguide plane is formed between a recessed plane 7 which is recessedly formed in the direction of the axis of the flange 2, and a projecting plane 8 which is formed so as to be engaged the recessed part 7 of the opposite flange.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a choke flange of a waveguide used for, for example, a heating device using microwave power, a plasma generator, a particle accelerator, and the like.

[0002]

2. Description of the Related Art Conventionally, high-power microwaves of the order of megawatts (hereinafter referred to as "MW") have been mainly used for accelerating an electron beam in a particle accelerator or the like.
For such microwave transmission, a waveguide system, particularly one in which a plurality of rectangular waveguides are connected, is often used.

[0003] A contact-type butt flange generally used for connecting a waveguide needs to have good processing accuracy of a joint surface of the waveguide, and the joint surface has a sufficient tightening force without any gap. Is required. When transmitting large power by microwaves, a large high-frequency current flows through the connection part of the waveguide, so if there is a gap in the joint surface of the flange of the connection part, radio waves may leak, and the high-frequency current flowing into the gap The physical and chemical action of the compound may lead to the formation of a substance that causes discoloration of the flange surface and poor contact. On the other hand, a choke flange that does not directly contact the waveguide surface is suitable for transmission of large microwave power because a large tolerance in mechanical dimensions can be obtained.

[0004] The principle of operation of the choke flange will be described below. The choke flange of the waveguide has a half-wavelength short-circuited series branch circuit between the two waveguides without directly contacting the inner surfaces of the connected waveguides (both flanges). is there. FIG. 3A is a longitudinal sectional view showing an example of a choke flange of a commonly used waveguide.
(B) is a front view of the choke flange. FIG.
In (a) and (b), 11 and 11 are two waveguides to be connected, 12 is a choke flange, and 13 is a flange on the other side.
Narrow gap (gap of waveguide surface) 15 between the choke flange surface of the waveguide connection portion and the mating flange surface
Are formed. This gap 15 communicates with the coaxial waveguide 14 whose edge is provided parallel to the waveguide axis.
In the gap 15 on the waveguide surface, the current distribution forms a radial line, and in the coaxial waveguide 14, the TE ₁₁ mode is mainly transmitted. The tip portion 16 of the coaxial waveguide 14 is a short-circuit surface of the TE ₁₁ mode, and the coaxial waveguide 14 forms a choke circuit together with the gap 15 of the waveguide surface.

[0005] In the gap 15 on the waveguide surface, the distribution of electric field, magnetic field and current forms a radial line having a quarter wavelength. Assuming that the length of the coaxial waveguide 14 is １ ／ wavelength of the TE ₁₁ mode, 先端 that short-circuits the tip 16 thereof
Since the transmission line has a wavelength, almost no current flows across the contact surface 17 of the flange, so that even if the contact is slightly poor, there is almost no effect. Further, there is low the characteristic impedance by narrowing the transmission line of TE ₁₁ mode of the radial line and the coaxial waveguide 14. As a result of these actions, the gap 15 operates as if it were electrically short-circuited. This is the principle of operation of the choke flange.

[0006]

However, the choke flange has a structure of a radial mode or TE of a coaxial waveguide due to its structure.
It requires a quarter wavelength length of ₁₁ modes. Therefore, the structure becomes large, the weight becomes heavy, the layout is restricted, and the handling is not easy. Further, it is inevitable that the manufacturing cost is higher than that of the butt flange.

The present invention has been proposed in view of the above circumstances, and an object of the present invention is to provide a choke flange for a waveguide that is small, lightweight, and not expensive to manufacture.

[0008]

That is, the choke flange of the waveguide according to the present invention is characterized in that the mechanical size of the choke circuit is shortened by arranging a dielectric in a space portion forming the choke circuit. And

The space forming the choke circuit is:
When the waveguide is rectangular, the (coaxial) waveguide is located outside the opening of the rectangular waveguide and has a rectangular shape similar to the rectangular waveguide. The gap of the waveguide surface is provided between a concave surface formed by being depressed in the axial direction of the choke flange and a convex surface formed to be fitted with the depressed portion on the mating flange. Is preferred.

The choke circuit of the choke flange according to the present invention includes a coaxial waveguide (parallel to the axial direction of the waveguide) of 1/4 wavelength of the TE ₁₁ mode short-circuited tip and a 1/4 wavelength of the radial mode.
It is formed by a gap (perpendicular to the axial direction of the waveguide) of the waveguide surface of a wavelength length. In a conventional choke flange, the mechanical portion is necessarily long because the space forming these choke circuits is air. The present invention intends to reduce the mechanical size by arranging a dielectric material in this space portion by the wavelength shortening effect.

In the present invention, the dielectric material arranged in the choke circuit may be filled in the space for forming the choke circuit without any gap or may be partially present, and the gap may be partially formed. You may. If there is some form of dielectric in the space that forms the choke circuit,
This is because the wavelength becomes shorter. When the space is filled with a dielectric without gaps, the wavelength shortening effect is maximized.

The dielectric disposed in the space portion is not particularly limited as long as it has low power loss. Practically, plastics such as polyethylene and polytetrafluoroethylene (tetrafluoroethylene resin) or ceramics such as alumina are used. Any of these substances is conveniently used as a molded article prepared according to the shape and size of the opening of the choke flange.

[0013]

In the present invention, a dielectric is disposed in a space where a choke circuit is formed, and the mechanical size of the choke circuit is shortened by its wavelength shortening effect. Since the characteristic impedance of the choke circuit is reduced by disposing the dielectric, the frequency characteristic of the input impedance as viewed from the gap on the waveguide surface is closer to a short circuit. Therefore, the operation of the choke circuit is further improved as compared with a normal choke circuit. When the dielectric is partially disposed in the choke circuit, the effect of shortening the wavelength is reduced, but it is apparent that the choke circuit operates as a choke circuit by appropriately selecting its mechanical dimensions.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A choke flange according to the present invention will be specifically described based on an embodiment shown in the drawings.
FIG. 1A is a cross-sectional view showing one embodiment of a choke flange used for connecting a rectangular waveguide according to the present invention, and FIG.
Is a front view thereof.

In FIGS. 1 (a) and 1 (b), 1.1
Are waveguides to be connected to each other, and each of the waveguides 1 is a rectangular waveguide having a flat rectangular tube shape in the illustrated example, and a rectangular choke flange is provided at an end of one of the waveguides. 2,
A mating flange 3 fitted with the choke flange 2 is integrally provided at the end of the mating waveguide to be connected by welding or brazing. Its two flanges 2 and 3
Through holes are formed at substantially equal intervals at a plurality of positions in the circumferential direction, and the through holes are provided so as to coincide with each other when the two flanges 2 and 3 face each other as shown in FIG. Have been.

As shown in FIGS. 1A and 1B,
The waveguides 1 to be connected to each other are not in direct contact with each other, but have a concave surface 7 formed by being recessed in the axial direction of the choke flange 2 and a convex surface 8 formed in the mating flange 3 so as to be fitted with the recess. Space portions 4 and 5 forming a choke circuit are provided between them. 4 of this space part is a coaxial waveguide,
Reference numeral 5 denotes a gap on the waveguide surface, and the periphery of the gap 5 is connected to one end of the coaxial waveguide 4. The tip 6 of the coaxial waveguide 4 is a TE ₁₁ mode short-circuit surface, and the coaxial waveguide (part of the choke circuit) 4 which is a TE ₁₁ mode transmission line is formed on the choke flange 2 of the rectangular waveguide 1. Outside the opening, a rectangular narrow groove similar to the rectangular waveguide is provided. The gap 5 on the waveguide surface forms a radial line portion (a part of a choke circuit) during microwave transmission. The space portions 4 and 5 are filled with a molded article of polytetrafluoroethylene as a dielectric. FIG. 2 is a perspective view showing an example of the shape of the filled dielectric 20. In FIG. 2, (21) is a portion that fills the dielectric coaxial waveguide 4, and (22) is a portion that fills the gap 5 of the dielectric waveguide surface. In FIG. 1A, reference numeral 9 denotes a gasket fitted into a groove provided along the opening of the rectangular waveguide 1 in the mating flange 3.

Although the method of connecting the choke flanges with a bolt and a nut has been exemplified, the “waveguide connection device” proposed by the present inventors (application number: Japanese Patent Application No. 359375/1996). ) May be applied. For example, 1) a tapered surface is provided on the opposite side of the joint surface between the choke flange and the mating flange to be connected, and the clamp piece is engaged with the tapered surface, and the clamp piece having a substantially V-shaped cross section, A method of connecting using a connecting clamp comprising a fastening means for pressing against a surface, 2) disposing a tapered surface forming member having a substantially triangular cross section on the surface opposite to the joint surface of the two choke flanges. It is also possible to apply a connection method in which the tapered surface is formed thereby, or 3) a connection method in which the tapered surface forming member having a substantially triangular cross section is connected in advance with a thin sheet-shaped connecting member. It is.

[0018]

As described above, since the choke flange according to the present invention has the above-described structure, the choke flange is small and lightweight, and the external dimensions are such that the thickness of the flange portion of the normal contact type butt flange is slightly increased. And easy to handle. Moreover, since it is a choke flange, it is suitable for high-power microwave transmission, and the processing cost can be lower than that of a normal choke flange. Therefore, the choke flange according to the present invention is extremely effective in a device that connects a large number of waveguides, such as a particle accelerator and a high-power microwave transmission device.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing an example of a choke flange according to the present invention. FIG.

FIG. 2 is a perspective view showing an example of a shape of a dielectric filling a choke circuit.

FIG. 3A is a sectional view showing an example of a conventional choke flange. FIG.

[Explanation of symbols]

 1,11 Rectangular waveguide 2,12 Choke flange 3,13 Mating flange 4,14 Coaxial waveguide 5,15 Gap of waveguide surface 6,16 Tip of coaxial waveguide 7 Concave surface of choke flange 8 Mating Convex surface of flange 17 Contact surface of flange 20 Dielectric

Claims (2)

[Claims] In a choke flange of a rectangular waveguide, a space portion forming a choke circuit has a rectangular thin film similar to the rectangular waveguide formed outside a gap between a waveguide surface and a rectangular waveguide opening. And a waveguide provided as a groove,
A choke flange for a waveguide, wherein a dielectric is disposed in the space. 2. The gap between the waveguide surfaces is provided between a concave surface formed by recessing in the axial direction of the choke flange and a convex surface formed in the mating flange so as to fit into the recess. The choke flange of the waveguide according to claim 1.