JPH0870204A - Radio wave absorbing device - Google Patents

Abstract

PURPOSE: To realize the device offering ease of maintenance by securing an envelope shape by tops of elements without giving damages to the radio wave absorbing elements in the manufacture process. CONSTITUTION: A radio wave absorbing element 1 is joined to a thin metallic base plate 2 to form each of plural absorbing units 3, and each absorption unit 3 is fixed to each hole provided to side walls of a waveguide 4 having an opening at its one end opposite to each other in a manner that the radio absorbing element 1 is directed in the inner direction and the metallic base plate 2 is fixed to the inner face of the hole. Then a curve formed by tying tops of the radio wave absorbing elements 1 forms an envelope to allow a bent of each metallic base plate 2 to be easily corrected thereby securing high shape precesion without a damaged element 1 when the radio wave absorbing element 1 is joined to the metallic base plate 2. Since the performance is confirmed in the state of tentative assembling, a nonreflecting characteristic is obtained with high precision and maintenance is facilitated because the replacement of each absorbing unit 3 is easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave absorber applied to a non-reflective end of a high frequency transmission circuit of a particle accelerator using high frequency power, an acceleration cavity and the like.

[0002]

2. Description of the Related Art A conventional high frequency wave absorber is shown in FIG.
The water loading method shown in FIG. 3A, the method using a sintered solid such as SiC shown in FIGS. 3B and 3C, and FIG.
There is a system using an element such as SiC shown in (d) (Japanese Patent Application No. 04-015737).

In the structure shown in FIG. 3 (a), the water 11 serving as a load in the waveguide 10 is a radio wave passage window (ceramic partition plate) 1
Radio waves are absorbed through 2, but there is a risk that water will enter the three-dimensional circuit system when the window is broken.

FIG. 3 (b) shows a metal waveguide 13
The radio wave absorber 14 is bonded to the absorber 14 to absorb the absorbed power.
The heat generated by is absorbed by the cooling water flowing outside the metal waveguide 13. However, when the absorbed power is large, the difference in thermal expansion between the wave absorber 14 and the metal waveguide 13 causes the absorption of radio waves. Since the body 14 is easily damaged, it was unsuitable for use as a large radio wave absorber.

FIG. 3C shows a metal waveguide 15
Although the structure is such that the shell-shaped absorber 16 is coupled to and the absorber 16 is directly water-cooled, if the ceramic absorber 16 is broken, there is a risk that cooling water may enter the three-dimensional circuit.

In FIG. 3D, a plurality of ceramic wave absorber elements 1 are provided on the inner wall of the waveguide 17.
8 is provided and the outer wall of the waveguide 17 is water-cooled, the electromagnetic wave absorber element 18 can be easily molded, and the element 18 can be securely joined to the inner wall of the waveguide 17. Since it can be performed at any temperature, the heat transfer is surely performed, which is superior to any of the electromagnetic wave absorbers shown in FIGS. 3 (a), (b), and (c).

[0007]

The conventional radio wave absorber provided with the radio wave absorber element shown in FIG. 3 (d) is shown in FIGS. 3 (a), 3 (b) and 3 (c) as described above. It was superior to any radio wave absorber.

However, the wave absorber element made of SiC or the like and the metal waveguide for cooling are joined by brazing. When a silver brazing material is used as the brazing material, the brazing material is heated to about 800.degree. As shown in FIG. 4, during the temperature lowering process, a shearing force acts on the joint surface of the absorber element due to the difference in the thermal expansion coefficient between the ceramic absorber element and the metal waveguide, and the electromagnetic wave absorber element It was easy to crack.

Further, the metal waveguide provided with the electromagnetic wave absorber element is, as shown in FIG. 5 (a), a half waveguide 17a which is divided into two by a dividing line along the axial direction. After the waveguide assembly 19 is manufactured, the waveguide assembly 19 is brazed. During the brazing, since the metal waveguide has rigidity, the absorber joint portion is likely to be cracked.

In order to prevent this, when the plate thickness of the metal waveguide is reduced to reduce the rigidity of the metal waveguide, local bending occurs, and the envelope of the absorber array as shown in FIG. 5 (b) is generated. The line shape could not be secured.

Furthermore, if even one of the disposed absorber elements is damaged (cracked or peeled), the entire reflector becomes unusable due to the loss of its reflection characteristics and must be replaced during use. There was a problem that I could not do it. The present invention is intended to solve the above problems.

[0012]

The radio wave absorber according to the present invention comprises:
A plurality of absorber units which are formed by joining the respective wave absorber elements having radio wave absorption characteristics to the respective metal substrates and have different heights of the respective wave absorber elements, and the plurality of absorber units absorb the radio waves. The body element is inserted inward and the metal substrate is fixed to the side walls, and the holes are provided in the opposite side walls, and one end is open and the other end is closed. It is characterized in that the curve connecting the tops of the radio wave absorber elements of the absorber unit forms an envelope shape.

[0013]

In the above, since the electromagnetic wave absorber element is joined to the thin metal substrate, the shearing force acting on the element at the time of joining is relaxed as compared with the conventional device,
The element is not damaged, and the bending generated in the metal substrate can be easily corrected, and high shape accuracy can be secured.

In addition, since the electromagnetic wave absorption performance of the waveguide in which the absorber unit is arranged can be confirmed in advance in a temporarily assembled state, it is possible to secure a highly accurate antireflection property after the assembly is completed. it can.

Further, since the metal substrate of the absorber unit is joined to the side wall of the waveguide from the outside thereof, it is easy to attach and detach the unit. Even if the part is damaged, it can be easily replaced and maintenance is easy.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In this embodiment shown in FIGS. 1 and 2, a cylindrical electromagnetic wave absorber element 1 made of SiC or the like having an electromagnetic wave absorption characteristic is joined to a metal substrate 2 made of a double disk thin plate having a thickness reducing portion 2a. A plurality of absorber units 3 formed by brazing the portions 1a and having different heights of the respective elements 1 described above, and a plurality of holes are provided in a zigzag shape in two opposing side walls, each hole being in a zigzag shape. The absorber unit 3 is inserted into the waveguide 4, the flange is provided at one end and the other end is closed, and the sidewall of the waveguide 4 is provided outside the sidewall where the absorber unit 3 is provided. And a water cooling jacket 6 through which cooling water 6a flows.

The absorber unit 3 includes the waveguide 4
After inserting the electromagnetic wave absorber element 1 into the respective holes provided in, the respective metal substrates 2 are fitted into the respective holes, and the bottom end of the metal substrate 2 is attached to the waveguide 4. It is joined to the side wall by welding or the like. The curve connecting the tops of the electromagnetic wave absorber elements 1 of the absorber unit 3 arranged in the waveguide 4 forms an envelope shape.

In the above, since the radio wave absorber element 1 is joined to the thin metal substrate 2 by brazing at the joint portion 1a, the shearing force acting on the radio wave absorber element 1 at this joining time is larger than that in the conventional device. Therefore, the element 1 can be prevented from being damaged. In addition, the bending of the metal substrate 2 can be easily corrected, and high shape accuracy can be secured.

Further, the absorber unit 3 formed by joining the radio wave absorber element 1 and the metal substrate 2 is arranged on the side wall of the waveguide 4 to form the absorber assembly 8.
Since the radio wave 7 can be sent from the flange 5 side of the waveguide 4 to check the performance in advance when the absorber assembly 8 is in the temporary assembly state, it is possible to obtain highly accurate anti-reflection characteristics after the assembly is completed.

Further, in the absorber unit 3, the bottom end of the metal substrate 2 is joined to the inner surface of the hole of the side wall of the waveguide 4 by welding or the like. Since it can be easily removed, it can be easily replaced even if some of the plurality of absorber units 3 are damaged during use, and maintenance is easy.

[0021]

In the radio wave absorber of the present invention, the radio wave absorber element is bonded to the thin metal substrate to form a plurality of absorber units, and the absorber units are provided on the opposite side walls of the waveguide having an opening at one end. The absorber unit is inserted into the bored hole with the electromagnetic wave absorber element facing inward, the metal substrate is fixed to the inner surface of the hole, and the curve connecting the tops of the electromagnetic wave absorber elements forms an envelope shape. By
Since the metal substrate is a thin plate, the element is not damaged when the electromagnetic wave absorber element is joined to the metal substrate, and the bending of the metal substrate can be easily corrected to ensure high shape accuracy, and temporary assembly Since the performance can be confirmed in this state, a highly accurate non-reflective characteristic can be obtained, and since the individual absorber units can be easily replaced, a device that can be easily maintained is realized.

[Brief description of drawings]

FIG. 1 is an explanatory view of a radio wave absorber according to an embodiment of the present invention, (a) is a perspective view of an absorber unit, (b) is a side view of the absorber unit, and (c) is an absorber unit. FIG. 3D is a side view of a state where the wave absorber is attached to the waveguide, and FIG.

FIG. 2 is a perspective view of a radio wave absorber according to the above embodiment.

FIG. 3 is an explanatory view of a conventional device, (a) is a water load type, (b) and (c) are types using a sintered solid,
(D) is an explanatory view of a system using a radio wave absorber element.

4A and 4B are explanatory views of the operation of the above-mentioned conventional apparatus, in which FIG. 4A is when an element is installed, FIG. 4B is when heating / bonding, FIG.
(D) is an explanatory view at the time of returning to normal temperature.

FIG. 5 is an explanatory view of assembly of the above-mentioned conventional device, (a)
Is a half waveguide assembly, and (b) is an explanatory diagram of an envelope.

[Explanation of symbols]

 1 Electromagnetic Wave Absorber Element 2 Metal Substrate 3 Absorber Unit 4 Waveguide 5 Flange 6 Water Cooling Jacket 8 Absorber Assembly

Claims (1)

[Claims] 1. A plurality of absorber units formed by joining respective wave absorber elements having radio wave absorption characteristics to respective metal substrates and having different heights of the respective wave absorber elements, and a plurality of the absorber units. The body unit includes a waveguide in which the electromagnetic wave absorber element is inserted inward and the metal substrate is fixed, and the holes are provided in opposite side walls and one end is open and the other end is closed. The electromagnetic wave absorber, wherein a curve connecting the tops of the electromagnetic wave absorber elements of the absorber unit fixed to the side wall of the electromagnetic wave forms an envelope shape.