A waveguide noise source with a low-reflection absorption load mounting structure

Abstract

The application provides a waveguide noise source with a low-reflection absorption load mounting structure. The noise source comprises a rectangular waveguide, a waveguide flange, a fine adjustment flange, a blind plate flange and an absorption load; the waveguide flange is fixedly connected to the input end of the rectangular waveguide; the fine adjustment flange is connected to the waveguide flange through fasteners; the blind plate flange is connected to the fine adjustment flange through fasteners; the fine adjustment flange is provided with a rectangular through hole; the position of the rectangular through hole corresponds to the position of the inner cavity of the rectangular waveguide; one end of the absorption load is fixed in the rectangular through hole; and the rest of the absorption load is arranged in the inner part of the rectangular waveguide. The fine adjustment flange of the application fixes one end of the absorption load, can make the absorption load closely contact with the inner wall of the rectangular waveguide by adjusting the relative position of the fine adjustment flange and the waveguide flange, improves the mounting reliability of the absorption load, and can obtain stable output low-reflection coefficient thermal noise.

Description

Technical Field

[0001] The present invention relates to the technical field of noise measurement, and in particular to a waveguide noise source with a low-reflection absorption load mounting structure. Background Art

[0002] The magnitude of thermal noise depends on the thermodynamic temperature of the object. Thermal noise standard noise sources based on thermodynamic temperature are used for noise parameter measurement and metrological calibration, and are widely used in many fields such as aerospace measurement and control, radio astronomy, radar, microwave remote sensing, electronic countermeasures, and communications. Depending on the temperature, thermal noise standard noise sources are divided into cold sources and hot sources. The cold source's absorption load is placed inside the rectangular waveguide, and the input end of the rectangular waveguide is immersed in liquid nitrogen for cooling. The absorption load outputs standard thermal noise through the output end of the rectangular waveguide at a temperature of 77.3K. The heat source's absorption load is placed inside the rectangular waveguide, and the input end of the rectangular waveguide is immersed in boiling water for heating. The absorption load outputs standard thermal noise through the output end of the rectangular waveguide at a temperature of 100°C.

[0003] Existing technologies use low-temperature adhesive to secure the absorbing load to the sidewalls of the rectangular waveguide cavity, achieving close contact between the absorbing load and the waveguide. The degree of close contact between the absorbing load and the waveguide affects the absorbing load's reflection coefficient. This existing low-temperature adhesive fixation method can easily loosen the absorbing load during use, resulting in low installation reliability and affecting the stable low-reflection-coefficient thermal noise output of the noise source. Summary of the Invention

[0004] An embodiment of the present invention provides a waveguide noise source with a low-reflection absorption load installation structure to solve the problem of low reliability of absorption load installation in the prior art.

[0005] In a first aspect, embodiments of the present invention provide a waveguide noise source with a low-reflection absorption load mounting structure, comprising: a rectangular waveguide, a waveguide flange, a fine-tuning flange, a blind flange, and an absorption load. The waveguide flange is fixedly connected to the input end of the rectangular waveguide. The fine-tuning flange is connected to the waveguide flange via fasteners. The blind flange is connected to the fine-tuning flange via fasteners. The fine-tuning flange is provided with a rectangular through-hole. The position of the rectangular through-hole corresponds to the position of the inner cavity of the rectangular waveguide. One end of the absorption load is fixed within the rectangular through-hole. The remainder of the absorption load is positioned within the rectangular waveguide.

[0006] In one possible implementation, a locating pin is provided on one flange surface of the fine-tuning flange, wherein the flange surface faces the waveguide flange. A locating hole is provided on one flange surface of the waveguide flange, wherein the flange surface faces the fine-tuning flange. The position of the locating hole corresponds to the position of the locating pin. The cross-sectional dimensions of the locating pin are smaller than the cross-sectional dimensions of the locating hole.

[0007] In a possible implementation manner, at least one side surface of the absorption load contacts an inner wall of the rectangular waveguide.

[0008] In one possible implementation, a first central axis of the rectangular waveguide and a second central axis of the rectangular through hole do not coincide with each other. The first central axis is parallel to the length of the rectangular waveguide, and the second central axis is perpendicular to the flange surface of the fine-tuning flange.

[0009] In a possible implementation, the first central axis of the rectangular waveguide passes through a horizontal symmetry axis or a vertical symmetry axis of a cross section of the rectangular through hole. The cross section of the rectangular through hole is parallel to a flange surface of the fine-tuning flange.

[0010] In a possible implementation, the first central axis of the rectangular waveguide passes through a diagonal line of a cross section of the rectangular through hole, and the cross section of the rectangular through hole is parallel to a flange surface of the fine-tuning flange.

[0011] In one possible implementation, the load absorbing section includes a mounting section and an absorbing section. The mounting section is in the shape of a square column, and the absorbing section is in the shape of a wedge. One end of the mounting section away from the absorbing section is fixed in the rectangular through hole.

[0012] In a possible implementation, the absorption section is shaped like an inclined quadrangular pyramid, wherein two adjacent first side surfaces of the inclined quadrangular pyramid are perpendicular to the bottom surface, and at least one of the first side surfaces contacts the inner wall of the rectangular waveguide.

[0013] In a possible implementation, the material for absorbing the load is carbonyl iron.

[0014] In a possible implementation, sealing rings surrounding the rectangular through hole are respectively provided on both sides of the fine-tuning flange.

[0015] An embodiment of the present invention provides a waveguide noise source with a low-reflection absorption load mounting structure, the noise source comprising a rectangular waveguide, a waveguide flange, a fine-tuning flange, a blind flange, and an absorption load; the waveguide flange is fixedly connected to the input end of the rectangular waveguide; the fine-tuning flange is connected to the waveguide flange via fasteners; the blind flange is connected to the fine-tuning flange via fasteners; a rectangular through hole is provided on the fine-tuning flange; the position of the rectangular through hole corresponds to the position of the inner cavity of the rectangular waveguide; one end of the absorption load is fixed in the rectangular through hole; and the rest of the absorption load is placed inside the rectangular waveguide. The fine-tuning flange of the present application fixes one end of the absorption load, and by adjusting the relative position of the fine-tuning flange and the waveguide flange, the absorption load is brought into close contact with the inner wall of the rectangular waveguide, thereby improving the installation reliability of the absorption load and obtaining stable output of low-reflection coefficient thermal noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 1 is a schematic diagram of a longitudinal cross-section structure of a waveguide noise source with a low-reflection absorption load mounting structure provided by an embodiment of the present invention;

[0018] Figure 2 is a right side view of the fine-tuning flange provided in an embodiment of the present invention;

[0019] Figure 3 1 is a schematic diagram of the longitudinal cross-sectional structure of the absorption load of the waveguide noise source provided by an embodiment of the present invention;

[0020] Figure 4 The waveguide noise source provided by the embodiment of the present invention is Figure 1 Schematic diagram of the cross-sectional structure at AA in the middle;

[0021] Figure 5 Schematic diagram of the inclined quadrangular pyramid absorbing load structure of the waveguide noise source provided by an embodiment of the present invention;

[0022] Figure 6 This is a graph showing the standing wave ratio test results of the absorption load provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] To help those skilled in the art better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of this solution, not all of it. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this solution.

[0024] Throughout the specification, claims, and accompanying figures of this solution, the term "including" and any variations thereof mean "including, but not limited to," and are intended to cover non-exclusive inclusions and are not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish between different objects, not to describe a specific order.

[0025] The following is a detailed description of the implementation of the present invention with reference to the accompanying drawings:

[0026] Thermal noise standard rectangular waveguide noise sources are divided into cold sources and hot sources according to different temperatures. The absorbing load of the cold source is placed inside the rectangular waveguide 1. The input end of the rectangular waveguide 1 is closed by a blind flange and a waveguide flange. The input end of the rectangular waveguide 1 is immersed in liquid nitrogen for cooling, and the absorbing load outputs standard thermal noise through the output end of the rectangular waveguide 1 at a temperature of 77.3K. The existing technology uses low-temperature glue to fix the absorbing load on the side wall of the inner cavity of the rectangular waveguide 1 to achieve close contact between the absorbing load and the rectangular waveguide 1. The degree of close contact between the absorbing load and the rectangular waveguide 1 affects the reflection coefficient of the absorbing load. The existing low-temperature glue fixing method makes the absorbing load easy to loosen during use, and the installation reliability is low, which in turn affects the stable low-reflection coefficient thermal noise output by the noise source.

[0027] Figure 1 A schematic diagram of the longitudinal cross-section structure of a waveguide noise source with a low reflection absorption load installation structure provided by an embodiment of the present invention. Figure 1 :

[0028] The noise source includes a rectangular waveguide 1, a waveguide flange 2, a fine-tuning flange 3, a blind flange 4, and an absorbing load 5. The waveguide flange 2 is fixedly connected to the input end of the rectangular waveguide 1. The fine-tuning flange 3 is connected to the waveguide flange 2 via fasteners 6. The blind flange 4 is connected to the fine-tuning flange 3 via fasteners 6. The fine-tuning flange 3 is provided with a rectangular through-hole 31. The position of the rectangular through-hole 31 corresponds to the position of the inner cavity of the rectangular waveguide 1. One end of the absorbing load 5 is fixed within the rectangular through-hole 31. The rest of the absorbing load 5 is located within the interior of the rectangular waveguide 1. The cross-sectional dimensions of the absorbing load 5 are smaller than the cross-sectional dimensions of the inner cavity of the rectangular waveguide 1.

[0029] The rectangular waveguide 1 is a hollow metal waveguide with a rectangular cross-section, designed to provide directionally transmitted electromagnetic waves within the waveguide. An absorbing load 5 is placed within the rectangular waveguide 1 to generate electromagnetic waves at a target temperature. The electromagnetic waves propagate within the rectangular waveguide 1 and are output through the output end of the rectangular waveguide 1. The waveguide flange 2 is fixed relative to the rectangular waveguide 1; that is, the input end of the rectangular waveguide 1 is fixedly connected to the waveguide flange 2. Exemplarily, the waveguide flange 2 is fixedly connected to the input end of the rectangular waveguide 1 by welding.

[0030] Figure 2 This is a right side view of the fine-tuning flange provided by an embodiment of the present invention. Figure 2 :

[0031] The fine-tuning flange 3 is connected to the waveguide flange 2 via fasteners 6. The blind flange 4 is also connected to the fine-tuning flange 3 via fasteners 6. That is, the waveguide flange 2, fine-tuning flange 3, and blind flange 4 are sequentially connected via fasteners 6. The fine-tuning flange 3 is positioned between the waveguide flange 2 and the blind flange 4. Exemplarily, the fasteners 6 may include, but are not limited to, one or more of the following: bolts, nuts, screws, and clamps. The removable fasteners 6 facilitate disassembly and replacement of the load absorber 5.

[0032] Exemplarily, fasteners 6 are bolts and nuts. Corresponding fixing holes are provided on waveguide flange 2, fine-tuning flange 3, and blind flange 4. The inner diameter of the fixing hole in fine-tuning flange 3 is larger than the outer diameter of the bolts. This means that the relative position of fine-tuning flange 3 and fasteners 6 is adjustable in a direction parallel to the flange surfaces.

[0033] The fine-tuning flange 3 is provided with a rectangular through hole 31 connecting the two flange surfaces. The position of the rectangular through hole 31 corresponds to the position of the inner cavity of the rectangular waveguide 1. The rectangular through hole 31 and the inner cavity of the rectangular waveguide 1 are used to place the absorbing load 5.

[0034] One end of the absorbing load 5 is fixed in the rectangular through hole 31, that is, the relative position of one end of the absorbing load 5 and the rectangular through hole 31 of the fine-tuning flange 3 is fixed. The relative position of the absorbing load 5 and the fine-tuning flange 3 is fixed. Exemplarily, the cross-sectional dimension of the end of the absorbing load 5 fixed in the rectangular through hole 31 is the same as the cross-sectional dimension of the rectangular through hole 31. The rest of the absorbing load 5 is placed inside the rectangular waveguide 1, wherein the cross-sectional dimension of the absorbing load 5 is smaller than the cross-sectional dimension of the inner cavity of the rectangular waveguide 1. That is, the absorbing load 5 is placed inside the rectangular waveguide 1, and the absorbing load 5 and the rectangular waveguide 1 can move relative to each other. The position of the absorbing load 5 can be adjusted by adjusting the position of the fine-tuning flange 3, thereby achieving the relative position adjustment of the absorbing load 5 and the rectangular waveguide 1.

[0035] The waveguide noise source provided by this embodiment of the present invention secures one end of the absorbing load 5 with a fine-tuning flange 3. Adjusting the relative position of the fine-tuning flange 3 and the waveguide flange 2 ensures close contact between the absorbing load 5 and the inner wall of the rectangular waveguide 1. This improves the installation reliability of the absorbing load 5 and achieves stable output with a low-reflection coefficient thermal noise. Compared to using low-temperature adhesive to secure the absorbing load 5, the fine-tuning flange 3 method offers ease of assembly and disassembly, making it convenient for absorbing load replacement.

[0036] In an optional embodiment, a locating pin 32 is provided on one flange surface of the fine-tuning flange 3, wherein the flange surface faces the waveguide flange 2. A locating hole 21 is provided on one flange surface of the waveguide flange 2, wherein the flange surface faces the fine-tuning flange 3. The position of the locating hole 21 corresponds to the position of the locating pin 32. The cross-sectional dimensions of the locating pin 32 are smaller than the cross-sectional dimensions of the locating hole 21.

[0037] The waveguide noise source provided by the embodiment of the present application can determine the installation direction of the absorbing load 5 through the positioning pin 32, so as to prevent installation errors. Meanwhile, the size of the positioning pin 32 is smaller than the size of the positioning hole 21, so that the relative position of the fine adjustment flange 3 and the waveguide flange 2 can be fine adjusted, and then the relative position of the fine adjustment absorbing load 5 and the rectangular waveguide 1 is fine adjusted, so that the fine adjustment absorbing load 5 is in close contact with the inner wall of the rectangular waveguide 1, and the installation reliability of the fine adjustment absorbing load 5 is improved, and the low reflection coefficient thermal noise with stable output can be obtained.

[0038] Figure 3 Fig. 2 is a longitudinal sectional structure schematic diagram of the absorbing load of the waveguide noise source provided by the embodiment of the present application. Referring to Figure 3

[0039] In an optional embodiment, the absorbing load 5 comprises an installation section 51 and an absorbing section 52. The shape of the installation section 51 is. The shape of the absorbing section 52 is a sharp wedge shape. The end of the installation section 51 away from the absorbing section 52 is fixed in the rectangular through hole 31. The rest of the installation section 51 and the absorbing section 52 are placed in the interior of the rectangular waveguide 1. The bottom surface of the sharp wedge shape is rectangular, and the other four side surfaces connected with the bottom surface are triangular, and the four triangular surfaces share a vertex. Exemplarily, the sharp wedge shape is a regular quadrangular pyramid. Exemplarily, the size of the bottom surface of the sharp wedge shape is the same as the size of the end surface of the above-mentioned square column shape.

[0040] Figure 4 Fig. 3 is a cross-sectional structure schematic diagram of the waveguide noise source provided by the embodiment of the present application at A-A. Referring to Figure 1 Figure 4

[0041] In an optional embodiment, at least one side surface of the absorbing load 5 is in contact with the inner wall of the rectangular waveguide 1. Exemplarily, one of the side surfaces of the installation section 51 of the absorbing load 5 is in contact with the inner wall of the rectangular waveguide 1. Exemplarily, two connected side surfaces of the installation section 51 of the absorbing load 5 are in contact with the inner wall of the rectangular waveguide 1.

[0042] In an optional embodiment, the first central axis of the rectangular waveguide 1 is not coincident with the second central axis of the rectangular through hole 31. The first central axis is a central axis parallel to the length direction of the rectangular waveguide 1; and the second central axis is a central axis perpendicular to the flange surface of the fine adjustment flange 3.

[0043] Exemplarily, the central axis perpendicular to the flange surface of the fine adjustment flange 3 is coincident with the second central axis of the rectangular through hole 31, i.e. the center of the rectangular through hole 31 is at the center of the fine adjustment flange 3. When the absorbing load 5 is installed, the relative position of the fine adjustment flange 3 and the rectangular waveguide 1 is adjusted, so that the absorbing load 5 is in contact with the inner wall of the rectangular waveguide 1.

[0044] ​​​For example, the fine adjustment flange 3 is not aligned with the second central axis of the rectangular through hole 31, i.e. the center of the rectangular through hole 31 deviates from the center of the fine adjustment flange 3. After the fine adjustment flange 3 is aligned with the first central axis of the rectangular waveguide 1, the second central axis of the rectangular through hole 31 is not aligned with the first central axis of the rectangular waveguide 1, i.e. the center of the rectangular through hole 31 deviates from the center of the rectangular waveguide 1.

[0045] The waveguide noise source provided by the embodiment of the present application has the rectangular through hole 31 arranged on the fine adjustment flange 3 and deviating from the central axis, and the absorption load 5 is fixed through the rectangular through hole 31. When the absorption load 5 is installed, the absorption load 5 is deviated from the inner wall of the rectangular waveguide 1, the position adjustment of the absorption load 5 is reduced, the installation of the absorption load 5 is facilitated, and the installation efficiency of the absorption load 5 is improved.

[0046] In an optional embodiment, the first central axis of the rectangular waveguide 1 passes through the horizontal or vertical symmetry axis of the cross section of the rectangular through hole 31. The cross section of the rectangular through hole 31 is parallel to the flange surface of the fine adjustment flange 3. That is, one side of the installation section 51 of the absorption load 5 is in contact with the inner wall of the rectangular waveguide 1.

[0047] In an optional embodiment, the first central axis of the rectangular waveguide 1 passes through the diagonal of the cross section of the rectangular through hole 31. The cross section of the rectangular through hole 31 is parallel to the flange surface of the fine adjustment flange 3. That is, two connected sides of the installation section 51 of the absorption load 5 are in contact with the inner wall of the rectangular waveguide 1.

[0048] Figure 5 FIG. 1 is a schematic diagram of a tilted quadrangular pyramid-shaped absorption load structure of a waveguide noise source provided by an embodiment of the present application. Referring to FIG. 1, the waveguide noise source comprises a rectangular waveguide 1 and an absorption load 5. The absorption load 5 is arranged in the rectangular waveguide 1. Figure 5 :

[0049] In an optional embodiment, the absorption section 52 is in the shape of a tilted quadrangular pyramid, wherein two adjacent first sides of the tilted quadrangular pyramid are perpendicular to the bottom surface. At least one first side is in contact with the inner wall of the rectangular waveguide 1. The two adjacent first sides of the tilted quadrangular pyramid are perpendicular to the bottom surface, i.e. one edge of the tilted quadrangular pyramid is perpendicular to the bottom surface of the tilted quadrangular pyramid.

[0050] In an optional embodiment, the material of the absorption load 5 is carbonyl iron. For example, first, a carbonyl iron disc with a thickness of 2 mm is prepared by using diamond wire cutting, and is cut into a cuboid with a size of 2 mm x 1 mm x 30 mm. Then, the absorption load 5 is prepared by using a bench grinding saw blade and cooperating with sandpaper.

[0051] In an alternative embodiment, the total length of the inclined quadrangular pyramid-shaped absorbing load 5 is 20 mm, the length of the mounting section 51 is 3.542 mm, and the length of the absorbing section 52 is 16.458 mm. The rectangular cross-section of the mounting section 51 measures 0.527 mm x 1.085 mm, i.e., the bottom surface of the inclined quadrangular pyramid-shaped absorbing section 52 measures 0.527 mm x 1.085 mm, and the length of one edge of the inclined quadrangular pyramid perpendicular to the bottom surface is 16.458 mm. The material of the absorbing load 5 is carbonyl iron.

[0052] Figure 6 This is a graph showing the standing wave ratio test results of the absorption load provided by an embodiment of the present invention. Figure 6 The horizontal axis is frequency (GHz); the vertical axis is standing wave ratio. The measured standing wave ratio of the inclined quadrangular pyramid absorbing load provided by the embodiment of the present invention is lower than 1.17 across the entire frequency band.

[0053] In the waveguide noise source provided by the present embodiment, the absorbing section 52 of the absorbing load 5 is shaped like an inclined quadrangular pyramid, with at least one first side surface perpendicular to the bottom surface contacting the inner wall of the rectangular waveguide 1. Compared to a quadrangular pyramid with equal edge lengths, the absorbing load 5 has a larger contact surface with the inner wall of the rectangular waveguide 1, resulting in better contact with the rectangular waveguide 1. The inclined quadrangular pyramid-shaped absorbing load 5 only requires grinding on two surfaces, resulting in a simple structure and ease of fabrication.

[0054] In an optional embodiment, a sealing ring is provided on each side of the fine-tuning flange 3, surrounding the rectangular through-hole 31. The inner diameter of the sealing ring is greater than the diagonal length of the cross-section of the rectangular through-hole 31. These sealing rings are used to seal the blind flange 4, the fine-tuning flange 3, and the waveguide flange 2, thereby ensuring a sealed state at the input end of the rectangular waveguide 1. Exemplarily, the sealing ring is made of polytetrafluoroethylene.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A waveguide noise source with a low reflection absorption load mounting structure, characterized in that: The noise source includes a rectangular waveguide, a waveguide flange, a fine-tuning flange, a blind flange and an absorbing load; The waveguide flange is fixedly connected to the input end of the rectangular waveguide; the input end of the rectangular waveguide is used to be placed in liquid nitrogen for cooling, so that the absorption load outputs standard thermal noise through the output end of the rectangular waveguide 1 at a temperature of 77.3K; The fine-tuning flange is connected to the waveguide flange via fasteners; The blind flange is connected to the fine-tuning flange via fasteners; A rectangular through hole is provided on the fine-tuning flange; the position of the rectangular through hole corresponds to the position of the inner cavity of the rectangular waveguide; One end of the absorbing load is fixed in the rectangular through hole; the rest of the absorbing load is placed inside the rectangular waveguide; wherein, the degree of close contact between the absorbing load and the inner wall of the rectangular waveguide is adjusted by adjusting the relative position of the fine-tuning flange and the waveguide flange.

2. A waveguide noise source with a low reflection absorption load mounting structure as claimed in claim 1, characterized in that: A positioning pin is provided on a flange surface of the fine-tuning flange, wherein the flange surface faces the waveguide flange; A positioning hole is provided on a flange surface of the waveguide flange, wherein the flange surface faces the fine-tuning flange, and the position of the positioning hole corresponds to the position of the positioning pin; The cross-sectional dimension of the positioning pin is smaller than the cross-sectional dimension of the positioning hole.

3. A waveguide noise source with a low reflection absorption load mounting structure as claimed in claim 1, characterized in that: At least one side surface of the absorbing load is in contact with an inner wall of the rectangular waveguide.

4. A waveguide noise source with a low reflection absorption load mounting structure as claimed in claim 3, characterized in that: The first central axis of the rectangular waveguide does not coincide with the second central axis of the rectangular through hole; The first central axis is a central axis parallel to the length direction of the rectangular waveguide; The second central axis is a central axis perpendicular to the flange surface of the fine-tuning flange.

5. A waveguide noise source with a low reflection absorption load mounting structure as claimed in claim 4, characterized in that: The first central axis of the rectangular waveguide passes through the horizontal symmetry axis or the vertical symmetry axis of the cross section of the rectangular through hole; The cross section of the rectangular through hole is parallel to the flange surface of the fine-tuning flange.

6. A waveguide noise source with a low reflection absorption load mounting structure as claimed in claim 4, characterized in that: The first central axis of the rectangular waveguide passes through a diagonal line of the cross section of the rectangular through hole; The cross section of the rectangular through hole is parallel to the flange surface of the fine-tuning flange.

7. The waveguide noise source with a low reflection absorption load mounting structure according to claim 1, characterized in that: The load absorbing section comprises a mounting section and an absorbing section; the mounting section is in the shape of a square column; the absorbing section is in the shape of a wedge; one end of the mounting section away from the absorbing section is fixed in the rectangular through hole.

8. A waveguide noise source with a low reflection absorption load mounting structure as claimed in claim 7, characterized in that: The shape of the absorption section is an inclined quadrangular pyramid, wherein two adjacent first side surfaces of the inclined quadrangular pyramid are perpendicular to the bottom surface; At least one of the first side surfaces contacts an inner wall of the rectangular waveguide.

9. A waveguide noise source with a low reflection absorption load mounting structure as claimed in claim 8, characterized in that: The material for absorbing the load is carbonyl iron.

10. The waveguide noise source with a low reflection absorption load mounting structure according to claim 1, characterized in that: Sealing rings surrounding the rectangular through hole are respectively provided on both sides of the fine-tuning flange.

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