WO2020103416A1

WO2020103416A1 - Horn antenna and radar level meter

Info

Publication number: WO2020103416A1
Application number: PCT/CN2019/088586
Authority: WO
Inventors: 周雷
Original assignee: 北京古大仪表有限公司; 周雷
Priority date: 2018-11-21
Filing date: 2019-05-27
Publication date: 2020-05-28

Abstract

Disclosed is a horn antenna, with a guided wave channel being formed inside the horn antenna, the horn antenna comprising a first portion located in a lower portion and a second portion located above the first portion, wherein the first portion and the second portion are hollow inside, and the cross-sectional area, which is enclosed by an outer side wall surface, of the first portion is larger than the cross sectional area, which is enclosed by an outer side wall surface, of the second portion. A radar level meter is further disclosed, comprising the horn antenna and a lens. The lens is fixed to the first portion of the horn antenna.

Description

Horn antenna and radar level meter

Technical field

The embodiments of the present application relate to but are not limited to the field of level gauges, and in particular, to but not limited to a horn antenna and radar level gauge.

Background technique

Radar level gauges usually include a horn antenna, and a tapered guided wave path is provided inside the horn antenna. The lower part of the horn antenna is provided with a connection section for fixed connection with the material tank for level measurement. The thickness of the connection section is thicker, which increases the weight of the radar level meter, and also increases the amount of material and the amount of the radar level meter. manufacturing cost.

Summary of the invention

The following is an overview of the topics detailed in this article. This summary is not intended to limit the scope of protection of the claims.

Embodiments of the present application provide a horn antenna and a radar level gauge with the horn antenna. The horn antenna has a reasonable structure, saves raw materials, and reduces manufacturing costs.

The technical solutions adopted in the embodiments of the present application are as follows:

An embodiment of the present application provides a horn antenna in which a guided wave path is formed, the horn antenna includes a first part located at a lower part and a second part located above the first part, the first part and all The interior of the second portion is hollow, and the cross-sectional area enclosed by the outer sidewall surface of the first portion is greater than the cross-sectional area enclosed by the outer sidewall surface of the second portion.

An embodiment of the present application further provides a radar level gauge, including a horn antenna and a lens. The horn antenna is the aforementioned horn antenna, and the lens is fixed to the first part of the horn antenna.

After reading and understanding the outline of the drawings and the embodiments of the present application, other aspects can be understood.

Brief description of the drawings

1 is a schematic cross-sectional structure diagram of a radar level gauge according to an embodiment of the present application;

2 is an enlarged schematic view of the structure of part A in FIG. 1;

Figure 3 is an enlarged schematic view of the structure of Part B in Figure 1;

4 is a schematic diagram of an exploded structure of a radar level gauge according to an embodiment of the present application;

5 is a schematic cross-sectional structural view of a radar level gauge according to another embodiment of this application;

FIG. 6 is an enlarged schematic view of the structure of part C in FIG. 5;

7 is a schematic diagram of an exploded structure of a radar level gauge according to another embodiment of the present application.

Reference mark:

1-horn antenna, 11-first part, 111-first spherical surface, 112-first air guide channel, 1121-air inlet, 1122-air outlet, 113-fixed groove, 114-step surface, 12-second part , 121-second spherical surface, 13-step surface, 14-waveguide path, 15-metal body, 151-inside wall surface, 16-non-metal housing, 161-projection, 1611-inside wall surface, 2-lens, 21 -Ring-shaped fixing part, 211-ring-shaped air guide groove, 3-mounting flange, 31-first mounting through hole, 32, 33-screw fixing hole, 4-pressure plate, 41-second mounting through hole, 42- avoidance hole , 43-screw fixing hole, 5-purge joint, 6-seal ring, 7-stop ring, 71-fixing protrusion, 8-screw, 9-insulation sheet.

Elaborate

The embodiments of the present application will be described in detail below with reference to the drawings.

As shown in FIGS. 1 and 5, the horn antenna 1 provided by the embodiment of the present application has a wave guide path 14 formed therein, and the wave guide path 14 may be tapered. The horn antenna 1 includes a first portion 11 located at a lower portion and a second portion 12 located above the first portion 11, the inner portions of the first portion 11 and the second portion 12 are hollow, and the cross-sectional area surrounded by the outer sidewall surface of the first portion 11 is larger than the second The cross-sectional area surrounded by the outer wall surface of the portion 12.

The horn antenna 1 provided by an embodiment of the present application includes a first portion 11 located at a lower portion and a second portion 12 located above the first portion 11, and the outer wall surface of the first portion 11 is larger in cross-sectional area than the outer wall surface of the second portion 12 The enclosed cross-sectional area. The horn antenna of the embodiment of the present application has a different shape from the horn antenna in the related art. The horn antenna 1 combined with the first part 11 and the second part 12 is used, which saves the use of manufacturing materials, especially the wall thickness of the second part 12 Lower, reduces the use of manufacturing materials, reduces the weight and manufacturing cost of the horn antenna 1, and increases the practicality of the horn antenna 1.

The first part 11 and the second part 12 cooperate to form a connecting section, which is used for fixed connection with the tank to be subjected to the level measurement, because the cross-sectional area enclosed by the outer wall surface of the first part 11 is larger than that of the outer wall surface of the second part 12 The enclosed cross-sectional area is convenient for the mounting flange 3 and the pressing plate 4 to be sleeved outside the first part 11 and the second part 12, respectively, and the mounting flange 3 and the pressing plate 4 are clamped by fixing the mounting flange 3 and the pressing plate 4 Fixed on the horn antenna 1. The mounting flange 3 is fixedly connected to the tank, so that the radar level gauge including the horn antenna 1 measures the height of the level in the tank, and the fixing method of the horn antenna 1 and the tank is simple and reliable.

In some embodiments, as shown in FIGS. 1 and 5, the outer sidewall surface of the first portion 11 may be a first spherical surface 111, and the outer sidewall surface of the second portion 12 may be a second spherical surface 121, and the spherical center of the first spherical surface 111 and The center of the second spherical surface 121 may not coincide.

The first spherical surface 111 and the second spherical surface 121 ensure that the horn antenna 1 meets work requirements such as strength, and facilitates the manufacture of the horn antenna 1. The spherical centers of the two spherical surfaces do not coincide, which is conducive to saving the material amount of the horn antenna 1 and reducing the manufacturing cost.

In other embodiments, the spherical centers of the first spherical surface 111 and the second spherical surface 121 may be arranged to coincide with each other.

It should be understood that the outer wall surface of the first portion 11 and the outer wall surface of the second portion 12 may also be aspherical, such as conical, elliptical, or other arc shapes.

In some embodiments, as shown in FIGS. 1 and 5, the cross-sectional area enclosed by the outer wall surface of the first portion 11 gradually decreases from top to bottom.

In some embodiments, as shown in FIGS. 1 and 5, the cross-sectional area surrounded by the outer wall surface of the second portion 12 gradually increases from top to bottom, or the cross-section surrounded by the outer wall surface of the second portion 12 The area increases from top to bottom and then decreases.

The cross-sectional area surrounded by the outer wall surface of the first part 11 gradually decreases from top to bottom, so that the mounting flange 3 is sleeved out of the first part 11 from below. The cross-sectional area surrounded by the outer wall surface of the second portion 12 gradually increases from top to bottom, or the cross-sectional area surrounded by the outer wall surface of the second portion 12 increases first and then decreases from top to bottom, so that the pressure plate 4 The second part 12 is sleeved from above. After the mounting flange 3 and the pressure plate 4 are fixedly connected, the mounting flange 3 and the pressure plate 4 are clamped and fixed on the horn antenna 1 due to the obstruction of the maximum cross-sectional area of the first portion 11 and the second portion 12, and the mounting flange The fixing method of 3 and the pressure plate 4 is simple and effective.

In some embodiments, as shown in FIGS. 1 and 5, a stepped surface 13 is formed between the first portion 11 and the second portion 12.

A stepped surface 13 is formed between the first portion 11 and the second portion 12 of the horn antenna 1 to avoid waste of extra materials and reduce manufacturing costs. In addition, after the step surface 13 is provided, a purge joint 5 can be provided on the step surface 13 for cleaning the radar level gauge to ensure accurate and reliable operation of the radar level gauge.

In some embodiments, as shown in FIG. 1, the first portion 11 is provided with a first air guide channel 112.

The first air guide channel 112 is used for ventilation, and its upper end is an air inlet 1121, and the air inlet 1121 is connected to the purge joint 5 provided on the step surface 13; the lower end of the first air guide channel 112 is an air outlet 1122, and The air outlet 1122 is provided on the inner side wall surface of the first part 11, and the air outlet 1122 is connected to the second air guide channel (detailed description below) on the lens 2 to blow the surface of the lens 2 to ensure the surface of the lens 2 is clean and avoid Dust and other impurities affect the work of the radar level gauge.

In some embodiments, as shown in FIGS. 1 and 2, the inner diameter of the lower part of the first part 11 is larger than the inner diameter of the upper part of the first part 11, and between the lower part of the first part 11 and the upper part of the first part 11 The step surface 114 is formed, the lower end of the lens 2 is supported on the stop ring 7, and the upper end is in contact with the step surface 114.

In some embodiments, as shown in FIG. 5, the horn antenna 1 includes a metal body 15 and a non-metallic shell 16. The non-metallic shell 16 is sleeved on the metal body 15, and the metal body 15 is provided with a waveguide 14.

The horn antenna 1 provided in this embodiment includes a metal body 15 and a non-metal casing 16. The non-metal casing 16 is sleeved on the metal body 15. The horn antenna 1 reduces the amount of metal materials and reduces the weight of the horn antenna 1. Since the non-metallic shell 16 covers the outside of the metal body 15, it will not affect the normal conduction of electromagnetic waves in the waveguide 14 inside the metal body 15, and the non-metallic shell 16 can be processed to meet the shape of the horn antenna 1 . Compared with complex contour processing of metal materials, complex contour processing of non-metallic materials is more convenient, the processing efficiency of the antenna 1 is improved, and processing time is saved. Therefore, the horn antenna 1 provided in this embodiment is light in weight, high in processing efficiency, and low in cost.

In a specific example, the non-metal casing 16 and the metal body 15 are fixed by injection molding.

The non-metal casing 16 and the metal body 15 of the horn antenna 1 are fixed by injection molding, the process is simple, the cost is low, and the fixation is reliable, which can meet the working requirements of the radar level meter.

In some embodiments, the material of the metal body 15 may be aluminum alloy or zinc alloy or stainless steel (such as 316L).

Aluminum alloy or zinc alloy or stainless steel not only ensures that electromagnetic waves can pass through the waveguide 14 smoothly, but also has the advantages of light texture, corrosion resistance and low price, which can effectively reduce the weight of the horn antenna 1 and increase the service life of the horn antenna 1 To reduce the overall cost of the radar level gauge.

In some embodiments, the non-metal casing 16 is a plastic casing or a rubber casing.

The plastic shell or the rubber shell has good processing performance, and can be injection molded outside the metal body 15, which is beneficial to reduce the processing time of the horn antenna 1 and improve the processing efficiency of the horn antenna 1.

In a specific example, as shown in FIG. 5, the lower end of the non-metallic housing 16 has a protrusion 161 protruding from the lower end of the metal body 15, and the first portion 11 may include the protrusion 161.

The protruding portion 161 of the non-metallic housing 16 can be used to mount the lens 2 and the retaining ring 7, the retaining ring 7 fixes the lens 2 on the exit side of the waveguide 14 of the antenna 1, the upper end surface of the lens 2 and the lower end surface of the metal body 15 In contact with each other, the lower end surface of the retaining ring 7 and the lower end surface of the non-metallic casing 16 can be substantially flat.

In a specific example, as shown in FIG. 6, the inner wall surface 1611 of the protrusion 161 is recessed from the inner wall surface 151 of the metal body 15.

The inner wall surface 1611 of the protrusion 161 is recessed in the inner wall surface 151 of the metal body 15, that is, the diameter of the inner wall surface 1611 of the protrusion 161 is larger than the diameter of the inner wall surface 112 of the metal body 15, so that the lens 2 can communicate with the waveguide 14 The entire exit corresponds exactly, so that the electromagnetic wave can be emitted through the lens 2 after passing through the waveguide 14 to reduce the scattering of the electromagnetic wave to the surroundings, reduce the reflection of the electromagnetic wave by the protrusion 161, and improve the measurement accuracy of the radar level meter.

In a specific example, as shown in FIG. 6, the non-metallic casing 16 is provided with a first air guide channel 112. The air outlet 1122 of the first air guide channel 112 is provided on the inner wall surface 1611 of the protrusion 161 and The air outlet 1122 communicates with the second air guide channel installed on the lens 2 in the protruding portion 161.

The second air guide channel on the lens 2 communicates with the first air guide channel 112 on the non-metallic housing 16 and is used to sweep the surface of the lens 2 to avoid accumulation of dust on the surface of the lens 2 and affect the normal operation and accuracy of the radar level gauge measuring.

An embodiment of the present application also provides a radar level gauge, as shown in FIGS. 1 and 5, including a horn antenna 1 and a lens 2, the horn antenna 1 is the horn antenna 1 above, and the lens 2 and the horn antenna 1 Part 11 is fixed.

The radar level gauge provided by the embodiment of the present application includes the horn antenna 1 and the lens 2 above, and the lens 2 is fixed in the first part 11 of the horn antenna 1. Using the horn antenna 1 described above greatly reduces the overall weight and manufacturing cost of the radar level gauge.

In some embodiments, as shown in FIGS. 1, 4, 5, and 7, the radar level gauge further includes a mounting flange 3 and a pressure plate 4, the mounting flange 3 is provided with a first mounting through hole 31, The flange 3 is sleeved outside the first portion 11, the pressure plate 4 is provided with a second mounting through hole 41, the pressure plate 4 is sleeved outside the second portion 12 of the horn antenna 1, and the mounting flange 3 and the pressure plate 4 are fixed.

Connect the mounting flange 3 and the pressure plate 4 together, so that the mounting flange 3 and the pressure plate 4 are clamped and fixed on the horn antenna 1. By fixedly connecting the mounting flange 3 to the material tank, the connection and fixing of the radar level gauge and the material tank are realized, and the connection is simple and the fixing is firm and reliable.

In some embodiments, a portion of the inner wall surface of the first mounting through hole 31 in the axial direction contacts the outer wall surface of the first portion 11, and a portion of the inner wall surface of the second mounting through hole 41 in the axial direction contacts the second The outer side walls of the portion 12 are in surface contact.

A portion of the inner wall surface of the first mounting through hole 31 in the axial direction is in contact with the outer wall surface of the first portion 11, that is, a portion of the inner wall surface of the first mounting through hole 31 in the axial direction is not in contact with the outer wall surface of the first portion 11 In contact, there is a gap between this portion and the outer side wall surface of the first portion 11 so that the first portion 11 can swing within the first mounting through hole 31 by an angle. A portion of the inner wall surface of the second mounting through hole 41 in the axial direction is in contact with the outer wall surface of the second portion 12, that is, a portion of the inner wall surface of the second mounting through hole 41 in the axial direction is outside the second portion 12 The wall surface is not in contact, and there is a gap between this portion and the outer side wall surface of the second portion 12 so that the second portion 12 can swing within the second mounting through hole 41 by an angle.

The first part 11 of the horn antenna 1 can swing a certain angle in the first mounting through hole 31, and the second part 12 can swing a certain angle in the second mounting through hole 41, so that the horn antenna 1 can be relative to the mounting flange 3 and the pressure plate 4 Swing a certain angle to adjust the angle of the radar level gauge to better measure the level in the tank.

In a specific example, as shown in FIG. 2, an intermediate portion (annular portion) of the inner wall surface of the first mounting through hole 31 in the axial direction contacts the outer wall surface of the first portion 11, and the inner side of the first mounting through hole 31 Both the upper part and the lower part of the wall surface in the axial direction are not in contact with the outer side wall surface of the first part 11. As shown in FIG. 3, the middle portion (annular portion) of the inner wall surface of the second mounting through hole 41 in the axial direction is in contact with the outer wall surface of the second portion 12, and the inner wall surface of the second mounting through hole 41 in the axial direction The upper and lower parts of the direction are not in contact with the outer wall surface of the second part 12.

In some embodiments, the portion of the inner wall surface of the first mounting through hole 31 that contacts the outer wall surface of the first portion 11 may have a certain height in the axial direction, that is, the inner wall surface of the first mounting through hole 31 and the outer side of the first portion 11 There is surface contact between the walls. In other embodiments, the inner side wall surface of the first mounting through hole 31 and the outer side wall surface of the first portion 11 are in line contact.

In some embodiments, the portion of the inner wall surface of the second mounting through hole 41 that contacts the outer wall surface of the second portion 12 may have a certain height in the axial direction, that is, the inner wall surface of the second mounting through hole 41 and the second portion 12 There is surface contact between the outer wall surfaces. In other embodiments, the inner side wall surface of the second mounting through hole 41 and the outer side wall surface of the second portion 12 are in line contact.

In some embodiments, as shown in FIGS. 4 and 7, the mounting flange 3 is provided with three (or other number) screw fixing holes 32, and the pressure plate 4 is provided with three screw fixing holes 43, and the mounting flange 3 And the pressure plate 4 can be fixedly connected by 3 screws 8. The mounting flange 3 is provided with four (or other number) screw fixing holes 33, so that the mounting flange 3 is fixed to the tank by screws.

In some embodiments, as shown in FIGS. 1, 4, 5 and 7, the stepped surface 13 of the horn antenna 1 is fixed with a purge connector 5, and the pressure plate 4 is provided with an escape hole 42 to avoid the purge connector 5 , The escape hole 42 communicates with the second mounting through hole 41.

The step surface 13 is connected and fixed with a purge connector 5 for communicating with the first air guide channel 112 on the first part 11 of the horn antenna 1 and the second air guide channel on the lens 2 to remove the dust on the surface of the lens 2 Wait. The pressure plate 4 is provided with an escape hole 42. The purge joint 5 is fixed on the stepped surface 13 through the escape hole 42. Since the escape hole 42 is close to the second installation through hole 41, the escape hole 42 communicates with the second installation through hole 41 , To facilitate the manufacture and installation of the pressure plate 4.

In some embodiments, as shown in FIGS. 1 and 5, there is a gap between the inner wall surface of the escape hole 42 and the outer wall surface of the purge joint 5. On the one hand, the setting of the gap facilitates the installation and removal of the purge joint 5; on the other hand, when the horn antenna 1 swings at a certain angle relative to the mounting flange 3 and the pressure plate 4, the purge joint 5 swings with it, and the gap The arrangement of the pressure plate 4 does not interfere with the swinging of the purge joint 5, so that the angle adjustment operation of the radar level gauge is smooth.

In some embodiments, as shown in FIGS. 1 and 5, the lens 2 is fixed in the first part 11 by a retaining ring 7. As shown in FIGS. 2 and 6, the inner wall surface of the first portion 11 is provided with a fixing groove 113, and the outer wall surface of the retaining ring 7 is provided with a fixing protrusion 71. The fixing protrusion 71 can be inserted into the fixing groove 113 to The retaining ring 7 is fixed to the first part 11. The lens 2 can be fixed to the first part 11 under the support of the retaining ring 7.

In other embodiments, a fixing protrusion may be provided on the inner wall surface of the first portion 11, and a fixing groove matching the fixing protrusion may be provided on the outer wall surface of the retaining ring 7 to install the retaining ring 7 to the first Part 11.

In some embodiments, a seal is provided between the lens 2 and the first part 11. In a specific example, as shown in FIGS. 2 and 6, two (or other number) sealing rings 6 are provided between the outer side wall surface of the lens 2 and the inner side wall surface of the first portion 11. In another specific example, the seal may be provided between the upper end surface of the lens 2 and the lower end surface of the metal body 15 or the seal may be provided between the upper end surface of the lens 2 and the stepped surface 114 of the first portion 11.

The seal is provided to ensure the tightness of the lens 2 and the antenna 1, to prevent external dust, corrosive gas, etc. from entering the radar level gauge from the connection, interfere with the normal and accurate operation of the radar level gauge, and affect the service life of the radar level gauge.

In some embodiments, as shown in FIGS. 1, 4, 5 and 7, the upper part of the horn antenna 1 is provided with an insulating sheet 9. The insulating sheet 9 may be made of polytetrafluoroethylene (PTFE).

In some embodiments, the retaining ring 7 is a non-metallic component, for example, the retaining ring 7 may be a plastic retaining ring.

In some embodiments, the lens 2 is made of polytetrafluoroethylene (PTFE).

In some embodiments, the horn antenna 1 is made of stainless steel (such as 316L).

In some embodiments, the lens 2 is provided with a second air guide channel. The second air guide channel includes an annular air guide groove 211 and an air outlet (not shown) communicating with the annular air guide groove 211. The annular air guide groove 211 is disposed on the outer wall surface of the lens 2 and communicates with the air outlet 1122 of the first air inlet channel 112 of the horn antenna 1.

After the lens 2 is mounted on the horn antenna 1, the outer side wall surface of the lens 2 is adjacent to the inner side wall surface of the horn antenna 1, and the annular air guide groove 211 and the air outlet 1122 of the first air guide channel 112 are provided outside the lens 2 The wall surface and the inner side wall surface of the horn antenna 1 make the air outlet 1122 of the first air guide channel 112 adjacent to and face the annular air guide groove 211 to facilitate the communication between the annular air guide groove 211 and the air outlet 1122 of the first air guide channel 112.

When the lens 2 needs to be cleaned, the wind from the purge joint 5 can enter the first air inlet channel 112 from the air inlet 1121, and then enter the annular air guide groove 211 through the air outlet 1122 of the first air inlet channel 112. Flow in the annular air guide groove 211, so that the entire annular air guide groove 211 is filled with wind, so that the wind from the air outlet of the second air guide channel can clean the lens 2 from all sides, blowing away the lens 2 Dust etc.

Since the annular wind guide groove 211 is provided on the lens 2 instead of the horn antenna 1, the electromagnetic wave reflection problem caused by the annular wind guide groove provided on the horn antenna 1 is avoided, and the measurement effect of the radar level gauge is good.

In some embodiments, the first air guide channel 112 has an air outlet 1122.

In other embodiments, the first air guide channel 112 has multiple air outlets 1122, and the multiple air outlets 1122 are evenly distributed along the circumferential direction of the horn antenna 1.

The first air guide channel 112 has a plurality of air outlets 1122, which helps reduce the wind resistance of the wind; the plurality of air outlets 1122 are evenly distributed along the circumferential direction of the horn antenna 1, which helps the wind evenly enter the annular air guide groove 211 , And then clean the lens 2 from all around.

In some embodiments, as shown in FIGS. 1-2, or as shown in FIGS. 5--6, the edge of the lens 2 is provided with an annular fixing portion 21, and the lower end surface of the annular fixing portion 21 is supported on the retaining ring 7, The upper end surface is in contact with the stepped surface 114 or the lower end surface of the metal body 15.

The annular air guide groove 211 may be provided on the outer wall surface of the annular fixing portion 21, and the air outlet hole is provided on the inner wall surface of the annular fixing portion 21.

In some embodiments, the second air guide channel may include a plurality of air outlet holes evenly distributed along the circumferential direction of the lens 2.

The plurality of air outlet holes of the second air guide channel are evenly distributed along the circumferential direction of the lens 2, so that the wind flowing from the plurality of air outlet holes can evenly blow the lens 2 from all around to blow off the dust on the lens 2.

In the descriptions in the embodiments of the present application, it should be noted that the orientation or positional relationship indicated by the terms “upper” and “lower” are based on the orientation or positional relationship shown in the drawings, only to facilitate the description of the implementation of the present application The examples and simplified descriptions do not indicate or imply that the structure referred to has a specific orientation, is constructed and operated in a specific orientation, and therefore cannot be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless otherwise clearly specified and defined, the terms “connection” and “installation” should be understood in a broad sense. For example, the term “connection” may be a fixed connection or a detachable connection, which may be Integrally connected; it can be directly connected, indirectly connected through an intermediate medium, or it can be the connection between two components. Those of ordinary skill in the art can understand the meaning of the above terms in the embodiments of the present application.

Although the embodiments disclosed in the present application are as above, the content described is only the embodiments adopted to facilitate understanding of the present application, and is not intended to limit the present application. Any technical person in the field to which this application belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in this application, but the patent protection scope of this application must still be The scope defined by the appended claims shall prevail.

Claims

A horn antenna in which a guided wave path is formed, wherein: the horn antenna includes a first part located at a lower part and a second part located above the first part, the first part and the second part Is hollow, and the cross-sectional area enclosed by the outer sidewall surface of the first portion is greater than the cross-sectional area enclosed by the outer sidewall surface of the second portion.
The horn antenna according to claim 1, wherein the outer wall surface of the first portion is a first spherical surface, and the outer wall surface of the second portion is a second spherical surface.
The horn antenna according to claim 2, wherein: the spherical center of the first spherical surface and the spherical center of the second spherical surface do not coincide;

Alternatively, the spherical center of the first spherical surface and the spherical center of the second spherical surface coincide.
The horn antenna according to any one of claims 1 to 3, wherein: the cross-sectional area surrounded by the outer wall surface of the first portion gradually decreases from top to bottom;

The cross-sectional area surrounded by the outer wall surface of the second portion gradually increases from top to bottom, or the cross-sectional area surrounded by the outer wall surface of the second portion increases from top to bottom and then decreases.
The horn antenna according to any one of claims 1 to 4, wherein the horn antenna includes a metal body and a non-metal casing, the non-metal casing is sleeved on the metal body, and the metal body is provided with The guided wave path.
The horn antenna according to claim 5, wherein the non-metal casing and the metal body are fixed by injection molding.
The horn antenna according to claim 5 or 6, wherein: the material of the metal body is aluminum alloy or zinc alloy or stainless steel;

The non-metal casing is a plastic casing or a rubber casing.
The horn antenna according to any one of claims 5-7, wherein: the lower end of the non-metallic housing has a protrusion protruding from the lower end of the metal body, and the first portion includes the protrusion , The inner wall surface of the protruding portion is recessed from the inner wall surface of the metal body.
The horn antenna according to any one of claims 1-8, wherein: a first air guide channel is provided on the first part, and an air outlet of the first air guide channel is provided inside the first part Wall surface.
The horn antenna according to any one of claims 1-9, wherein a stepped surface is formed between the first portion and the second portion.
A radar level gauge includes a horn antenna and a lens, wherein: the horn antenna is the horn antenna according to any one of claims 1-10, and the lens is fixed to the first part of the horn antenna.
The radar level gauge according to claim 11, wherein the radar level gauge further comprises a mounting flange and a pressure plate, the mounting flange is provided with a first mounting through hole, and the mounting flange is sleeved on Outside the first part, a second mounting through hole is provided on the pressure plate, the pressure plate is sleeved outside the second part of the horn antenna, and the mounting flange and the pressure plate are fixed.
The radar level gauge according to claim 12, wherein: a part of the inner wall surface of the first mounting through hole in the axial direction is in contact with the outer wall surface of the first portion, and the inner side of the second mounting through hole A part of the wall surface in the axial direction is in contact with the outer side wall surface of the second part.
The radar level gauge according to claim 12 or 13, wherein: a purge joint is fixed on the step surface formed between the first part and the second part of the horn antenna, and the pressure plate is provided with The escape hole of the purge joint is avoided, the escape hole communicates with the second installation through hole, and there is a gap between the inner side wall surface of the escape hole and the outer side wall surface of the purge joint.
The radar level gauge according to any one of claims 11-14, wherein: a second wind guide channel is provided on the lens, the second wind guide channel includes an annular wind guide groove and the annular wind guide An air outlet communicating with the air groove, the annular air guide groove is provided on the outer wall surface of the lens, and communicates with the air outlet of the first air guide channel of the horn antenna.