CN214121337U

CN214121337U - Radar level meter

Info

Publication number: CN214121337U
Application number: CN202120319322.8U
Authority: CN
Inventors: 呼秀山; 夏阳
Original assignee: Beijing Ruida Instrument Co ltd
Current assignee: Beijing Ruida Instrument Co ltd
Priority date: 2021-02-04
Filing date: 2021-02-04
Publication date: 2021-09-03
Anticipated expiration: 2031-02-04

Abstract

The present disclosure provides a radar level gauge for measuring a position of a material within a tank, comprising: a transceiving antenna for transmitting an electromagnetic wave of a predetermined frequency and receiving a reflected echo of the electromagnetic wave reflected by an object to be measured, and an extension antenna having one end connected to the transceiving antenna so that the electromagnetic wave transmitted through the transceiving antenna is outwardly transmitted through the extension antenna and the transceiving antenna receives the reflected echo of the electromagnetic wave transmitted through the extension antenna reflected by the object to be measured; wherein a portion of the extended antenna is located outside the tank, and a portion of the extended antenna is located inside the tank.

Description

Radar level meter

Technical Field

The present disclosure relates to a radar level gauge.

Background

In the prior art, all radar level gauges with the frequency of more than 60ghz are plastic lens antennas, and because the plastic has low temperature resistance, the highest temperature resistance of common plastic is about 200 degrees, the radar level gauges cannot be applied to high-temperature working conditions.

In addition, such radar level gauges are sensitive to solid dust and condensation and are therefore less effective when used in the presence of dust and moisture. However, the measuring solids generally have dust and the measuring liquids are often moist, which also limits the environment in which the radar level gauge can be used.

SUMMERY OF THE UTILITY MODEL

To solve one of the above technical problems, the present disclosure provides a radar level gauge.

According to an aspect of the present disclosure, there is provided a radar level gauge for measuring a position of a material within a tank, comprising:

a transmitting-receiving antenna for transmitting an electromagnetic wave of a predetermined frequency and receiving a reflected echo of the electromagnetic wave reflected by an object to be measured, an

An extension antenna, one end of which is connected to the transceiver antenna, so that the electromagnetic wave transmitted by the transceiver antenna is transmitted outward via the extension antenna, and the transceiver antenna receives a reflected echo of the electromagnetic wave transmitted by the extension antenna reflected by an object to be measured;

wherein a portion of the extended antenna is located outside the tank, and a portion of the extended antenna is located inside the tank.

According to the radar level gauge of at least one embodiment of the present disclosure, said transceiver antenna is a plastic lens transceiver antenna; and/or the extension antenna is a circular tube-shaped extension antenna.

According to at least one embodiment of the present disclosure, the radar level gauge, the extension antenna comprises:

the one end of waveguide portion is connected in send and receive antenna, the other end of waveguide portion is located in the tank body.

According to the radar level gauge according to at least one embodiment of the present disclosure, an end of the waveguide portion remote from the transceiver antenna is formed as a chamfered cut.

According to at least one embodiment of the present disclosure, the radar level gauge, the extension antenna further comprises:

the horn structure, the less one end of diameter of horn structure connect in the waveguide portion is kept away from the one end of receiving and dispatching antenna.

According to the radar level gauge according to at least one embodiment of the present disclosure, said extension antenna is connected to said transceiver antenna by means of a screw fit.

According to the radar level gauge according to at least one embodiment of the present disclosure, the transceiver antenna is formed with an external thread, and the extension antenna is formed with an internal thread, so that the transceiver antenna and the extension antenna are fixed in a manner that the internal thread of the extension antenna is matched with the external thread of the transceiver antenna.

According to at least one embodiment of the present disclosure, the radar level gauge, the transceiver antenna comprises:

and the lens is provided with an external thread on the circumferential wall surface of the lens, so that the receiving and transmitting antenna and the extension antenna are fixed by matching the extension antenna with the external thread.

The radar level gauge according to at least one embodiment of the present disclosure, comprises:

the probe is used for generating electromagnetic waves with preset frequency and transmitting the electromagnetic waves with the preset frequency through the transceiving antenna; and for receiving reflected echoes received via the transceiving antennas.

According to the radar level gauge according to at least one embodiment of the present disclosure, a contact position of the extension antenna with the probe is formed with a sealing structure such that the transceiver antenna is located inside the extension antenna.

According to the radar level gauge according to at least one embodiment of the present disclosure, an annular groove is formed at an end of the extension antenna close to the probe, such that a sealing structure is formed at a contact position of the extension antenna and the probe by disposing a sealing ring in the annular groove.

According to at least one embodiment of the present disclosure, the seal ring is an O-ring seal.

According to the radar level gauge according to at least one embodiment of the present disclosure, a lower end of the extension antenna is spaced apart from a surface of the material stored in the tank body.

According to the radar level gauge according to at least one embodiment of the present disclosure, the axis of the extension antenna is parallel to or coincides with the axis of the transceiver antenna.

According to at least one embodiment of the present disclosure, the diameter of the end of the extension antenna connected to the transceiving antenna is larger than the diameter of the transceiving antenna and/or larger than the diameter of the lens of the transceiving antenna.

The radar level gauge according to at least one embodiment of the present disclosure, further comprising:

the angle adjusting device is arranged on the tank body and used for adjusting the angle of the extension antenna relative to the tank body.

According to at least one embodiment of the present disclosure, the radar level gauge, the angle adjustment device comprises:

the mounting flange is arranged on the tank body, and a lower ball socket is formed on the mounting flange; and

a ball structure disposed in the lower socket;

the spherical structure is provided with a containing hole, the extension antenna is slidably arranged in the containing hole of the spherical structure and is guided through the containing hole; and the angle adjustment of the extension antenna relative to the tank body is realized through the sliding of the spherical structure relative to the lower ball socket.

According to the radar level gauge of at least one embodiment of the present disclosure, the angle adjusting device further comprises a fixing plate, wherein the fixing plate is provided with an upper ball socket, and the upper ball socket is matched with the spherical structure so as to fix the spherical structure between the fixing plate and the mounting flange when the fixing plate is fixed to the mounting flange.

According to at least one embodiment of the present disclosure, the radar level gauge, the angle adjustment device further comprises:

and the locking mechanism locks the extension antenna through the locking mechanism after the extension antenna moves to the preset position.

According to at least one embodiment of the present disclosure, the locking mechanism includes a fastening bolt, the spherical structure defines a threaded hole, the fastening bolt is engaged with the threaded hole, and when the fastening bolt is screwed into the threaded hole, one end of the fastening bolt contacts the extension antenna to fix the extension antenna.

According to the radar level gauge according to at least one embodiment of the present disclosure, at least one sealing structure is arranged between the extension antenna and the spherical structure for sealing a gap between the extension antenna and the spherical structure.

According to at least one embodiment of the present disclosure, the sealing structure is a sealing ring.

According to the radar level gauge of at least one embodiment of the present disclosure, an annular groove is opened on an inner wall of the receiving hole of the spherical structure, and the sealing ring is disposed in the annular groove.

According to the radar level gauge according to at least one embodiment of the present disclosure, the annular groove coincides with an axial center line of the receiving hole of the spherical structure.

According to the radar level gauge of at least one embodiment of the present disclosure, the extension antenna is provided with an air inlet hole, so that when gas is fed into the extension antenna through the air inlet hole, the extension antenna is cooled and dedusted.

a purge connection in communication with the air inlet to provide gas into the elongate antenna through the purge connection.

According to the radar level gauge of at least one embodiment of the present disclosure, the transceiver antenna is opened with an air inlet hole to provide air to the extension antenna through the air inlet hole.

According to the radar level gauge according to at least one embodiment of the present disclosure, a heat sink is provided outside the extension antenna to reduce a temperature of the extension antenna.

the valve structure, the one end of valve structure is fixed in the receiving and dispatching antenna, the other end of valve structure set up in the extension antenna to make the axial lead of valve structure, the axial lead of receiving and dispatching antenna and the axial lead of extension antenna are parallel or coincide.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.

FIG. 1 is a schematic structural view of a radar level gauge according to an embodiment of the present disclosure.

Fig. 2 to 4 are schematic structural views of an extended antenna according to an embodiment of the present disclosure.

FIG. 5 is a schematic structural view of a radar level gauge according to an embodiment of the present disclosure.

FIG. 6 is a schematic structural view of a radar level gauge according to an embodiment of the present disclosure.

Fig. 7 is a schematic structural view of an angle adjusting apparatus according to an embodiment of the present disclosure.

Fig. 8 is a schematic structural view of an angle adjusting apparatus according to another embodiment of the present disclosure.

Fig. 9 is a schematic view of a mounting position of a heat sink according to another embodiment of the present disclosure.

FIG. 10 is a schematic view of an installation location of a purge joint according to another embodiment of the present disclosure.

Fig. 11 is a schematic view of an installation position of a valve structure according to another embodiment of the present disclosure.

The reference numbers in the figures are in particular:

100 radar level gauge

110 probe

120 transceiver antenna

121 lens

130 extended antenna

131 waveguide part

132 horn structure

140 angle adjusting device

141 mounting flange

142 spherical structure

143 fixing plate

144 locking mechanism

150 purge joint

160 heat sink

170 valve structure

200 can body.

Detailed Description

The present disclosure will be described in further detail with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not to be construed as limitations of the present disclosure. It should be further noted that, for the convenience of description, only the portions relevant to the present disclosure are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict. Technical solutions of the present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

Unless otherwise indicated, the illustrated exemplary embodiments/examples are to be understood as providing exemplary features of various details of some ways in which the technical concepts of the present disclosure may be practiced. Accordingly, unless otherwise indicated, features of the various embodiments may be additionally combined, separated, interchanged, and/or rearranged without departing from the technical concept of the present disclosure.

The use of cross-hatching and/or shading in the drawings is generally used to clarify the boundaries between adjacent components. As such, unless otherwise noted, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement for a particular material, material property, size, proportion, commonality between the illustrated components and/or any other characteristic, attribute, property, etc., of a component. Further, in the drawings, the size and relative sizes of components may be exaggerated for clarity and/or descriptive purposes. While example embodiments may be practiced differently, the specific process sequence may be performed in a different order than that described. For example, two processes described consecutively may be performed substantially simultaneously or in reverse order to that described. In addition, like reference numerals denote like parts.

When an element is referred to as being "on" or "on," "connected to" or "coupled to" another element, it can be directly on, connected or coupled to the other element or intervening elements may be present. However, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element, there are no intervening elements present. For purposes of this disclosure, the term "connected" may refer to physically, electrically, etc., and may or may not have intermediate components.

For descriptive purposes, the present disclosure may use spatially relative terms such as "below … …," below … …, "" below … …, "" below, "" above … …, "" above, "" … …, "" higher, "and" side (e.g., as in "side wall") to describe one component's relationship to another (other) component as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use, operation, and/or manufacture in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below … …" can encompass both an orientation of "above" and "below". Further, the devices may be otherwise positioned (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, when the terms "comprises" and/or "comprising" and variations thereof are used in this specification, the presence of stated features, integers, steps, operations, elements, components and/or groups thereof are stated but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. It is also noted that, as used herein, the terms "substantially," "about," and other similar terms are used as approximate terms and not as degree terms, and as such, are used to interpret inherent deviations in measured values, calculated values, and/or provided values that would be recognized by one of ordinary skill in the art.

FIG. 1 is a schematic structural view of a radar level gauge 100 according to one embodiment of the present disclosure.

The radar level gauge 100 as shown in FIG. 1, for measuring a position of a material within a tank 200, said radar level gauge 100 comprising:

a transceiving antenna 120, the transceiving antenna 120 for transmitting an electromagnetic wave of a predetermined frequency and receiving a reflected echo of the electromagnetic wave reflected by an object to be measured, an

An extension antenna 130, one end of the extension antenna 130 being connected to the transceiver antenna 120, so that the electromagnetic wave transmitted by the transceiver antenna 120 is emitted outward via the extension antenna 130, and the transceiver antenna 120 receives a reflected echo of the electromagnetic wave transmitted by the extension antenna 130 and reflected by an object to be measured;

wherein, a part of the extension antenna 130 is located outside the tank 200, and a part of the extension antenna is located inside the tank 200.

Therefore, in the radar level gauge 100 of the present disclosure, the probe of the radar level gauge 100 is disposed at a predetermined distance from the tank 200 by the extension antenna 130, and a portion of the extension antenna 130 is disposed inside the tank 200, so that the probe 110 of the radar level gauge 100 is cooled, and the probe 110 of the radar level gauge 100 can be kept away from dust and moisture, and therefore, the radar level gauge 100 of the present disclosure has a wide application range, and can achieve a good technical effect even when being used in a high-temperature, dust and moisture environment.

In the present disclosure, preferably, the transceiver antenna 120 is a plastic lens transceiver antenna; and/or the extension antenna 130 is a circular tube-shaped extension antenna.

In the present disclosure, referring to fig. 2 to 4, the extension antenna 130 includes:

and a waveguide part 131, one end of the waveguide part 131 being connected to the transceiver antenna 120, and the other end of the waveguide part 131 being located inside the tank 200.

More preferably, an end of the waveguide 131, which is away from the transceiving antenna 120, is formed as a chamfered cut, and as an example, an included angle between an inclined plane in which the chamfered cut is located and a horizontal plane may be about 45 °.

In an optional embodiment of the present disclosure, the extension antenna 130 further includes:

a horn structure 132, wherein one end of the horn structure 132 with a smaller diameter is connected to one end of the waveguide portion 131 far away from the transceiving antenna 120.

In the present disclosure, preferably, the lower end of the extension antenna 130 is spaced from the surface of the material stored in the tank 200, so that the extension antenna 130 is not covered by the liquid level or the material level, in other words, the extension antenna 130 is higher than the highest point of the liquid level as a whole.

On the other hand, the material of the extension antenna 130 may be a metal having electromagnetic field shielding performance, such as stainless steel; or may be a non-metallic material having electromagnetic field shielding properties.

FIG. 5 is a schematic structural view of a radar level gauge according to an embodiment of the present disclosure. FIG. 6 is a schematic structural view of a radar level gauge according to an embodiment of the present disclosure.

In an alternative embodiment of the present disclosure, referring to fig. 5 and 6, the extension antenna 130 is connected to the transceiver antenna 120 by a screw-fit.

Preferably, the extension antenna 130 is flanged or screwed to the transceiver antenna 120 of the radar level gauge 100.

In one implementation form, the transceiver antenna 120 is formed with an external thread, and the extension antenna 130 is formed with an internal thread, so that the transceiver antenna 120 and the extension antenna 130 are fixed by matching the internal thread of the extension antenna 130 with the external thread of the transceiver antenna 120.

In an optional embodiment of the present disclosure, the transceiver antenna 120 includes: and a lens 121 having a male screw formed on a circumferential wall surface of the lens 121, wherein the transceiver antenna 120 and the extension antenna 130 are fixed to each other by fitting the male screw of the lens 121 to the female screw of the extension antenna 130.

In an alternative embodiment of the present disclosure, the radar level gauge 100 comprises:

a probe 110, the probe 110 being configured to generate an electromagnetic wave of a predetermined frequency and to cause the electromagnetic wave of the predetermined frequency to be emitted through a transceiving antenna 120; and for receiving reflected echoes received via the transceiving antenna 120.

More preferably, the contact position of the extension antenna 130 and the probe 110 is formed with a sealing structure, and the transceiver antenna 120 is located inside the extension antenna 130, so that the electromagnetic wave (e.g., microwave) passing through the lens can enter the inside of the extension antenna 130 and be further emitted into the tank.

On the other hand, an annular groove is formed at one end of the extension antenna 130 close to the probe 110, and a sealing structure is formed at a contact position of the extension antenna 130 and the probe 110 by arranging a sealing ring in the annular groove; more preferably, the sealing ring may be an O-ring.

In an optional embodiment of the present disclosure, the axis of the extension antenna 130 is parallel to or coincides with the axis of the transceiver antenna 120, for example, the axis of the extension antenna 130 is parallel to or coincides with the axis of the lens of the transceiver antenna 120

In the present disclosure, a diameter of an end of the extension antenna 130 connected to the transceiving antenna 120 is larger than a diameter of the transceiving antenna 120, and/or larger than a diameter of a lens of the transceiving antenna 120.

Fig. 7 is a schematic structural view of an angle adjusting apparatus according to an embodiment of the present disclosure. Fig. 8 is a schematic structural view of an angle adjusting apparatus according to another embodiment of the present disclosure.

In an alternative embodiment of the present disclosure, referring to FIGS. 7 and 8, the radar level gauge 100 further comprises: the angle adjusting device 140 is disposed on the can 200, and is used for adjusting an angle of the extension antenna 130 relative to the can 200.

As one implementation form, the angle adjusting device 140 includes:

a mounting flange 141, wherein the mounting flange 141 is arranged on the tank 200, and a lower ball socket is formed on the mounting flange 141; and

a ball structure 142, wherein the ball structure 142 is disposed at the lower socket;

the spherical structure 142 is provided with a receiving hole, and the extension antenna 130 is slidably disposed in the receiving hole of the spherical structure 142, and the extension antenna 130 is guided through the receiving hole; and the angle adjustment of the extension antenna 130 relative to the tank 200 is realized through the sliding of the spherical structure 142 relative to the lower ball socket, so as to adjust the wave sending angle and the measuring direction of the radar level gauge 100.

Preferably, the angle adjusting apparatus 140 further includes a fixing plate 143, and the fixing plate 143 defines an upper ball socket, and the upper ball socket is matched with the spherical structure 142, so that when the fixing plate 143 is fixed to the mounting flange 141, the spherical structure 142 is fixed between the fixing plate 143 and the mounting flange 141.

Preferably, the angle adjusting apparatus 140 further includes:

and a locking mechanism 144, for locking the extension antenna 130 by the locking mechanism 144 after the extension antenna 130 moves to a preset position.

In one implementation, the locking mechanism 144 includes a fastening bolt, and the spherical structure 142 defines a threaded hole, and the fastening bolt is engaged with the threaded hole, and when the fastening bolt is screwed into the threaded hole, one end of the fastening bolt contacts the extension antenna 130 to fix the extension antenna 130.

At least one sealing structure is disposed between the extension antenna 130 and the spherical structure 142, and the sealing structure is used for sealing a gap between the extension antenna 130 and the spherical structure 142.

For example, the sealing structure is a sealing ring, and in this case, an annular groove is formed on an inner wall of the receiving hole of the spherical structure 142, and the sealing ring is disposed in the annular groove.

In an alternative embodiment of the present disclosure, the annular groove coincides with the axis of the receiving hole of the spherical structure 142.

In the present disclosure, the extension antenna 130 is provided with an air inlet, so that when air is fed into the extension antenna 130 through the air inlet, the extension antenna 130 is cooled and dedusted.

Fig. 9 is a schematic view of a mounting position of a heat sink according to another embodiment of the present disclosure. FIG. 10 is a schematic view of an installation location of a purge joint according to another embodiment of the present disclosure.

More preferably, with reference to FIG. 10, the radar level gauge 100 further comprises:

a purge connection 150, said purge connection 150 communicating with said air intake to provide gas into said elongated antenna 130 through said purge connection 150.

As another implementation form, the transceiver antenna 120 and/or the probe 110 are provided with an air inlet hole, so as to provide air to the extension antenna 130 through the air inlet hole and use the air to cool and remove dust from the extension antenna 130, and also prevent water vapor or condensed water from being generated inside the extension antenna 130; that is, at this time, the air intake holes of the transceiver antenna 120 and/or the probe 110 communicate with the hollow portion of the extension antenna 130.

On the other hand, referring to fig. 9, a heat sink 160 is provided outside the extension antenna 130 to lower the temperature of the extension antenna 130.

In an alternative embodiment of the present disclosure, referring to FIG. 11, the radar level gauge 100 further comprises: one end of the valve structure 170 is fixed to the transceiver antenna 120, and the other end of the valve structure 170 is disposed on the extension antenna 130, such that the axial line of the valve structure 170, the axial line of the transceiver antenna 120, and the axial line of the extension antenna 130 are parallel or coincident.

In the description herein, reference to the description of the terms "one embodiment/mode," "some embodiments/modes," "example," "specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment/mode or example is included in at least one embodiment/mode or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to be the same embodiment/mode or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments/modes or examples. Furthermore, the various embodiments/aspects or examples and features of the various embodiments/aspects or examples described in this specification can be combined and combined by one skilled in the art without conflicting therewith.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

It will be understood by those skilled in the art that the foregoing embodiments are merely for clarity of illustration of the disclosure and are not intended to limit the scope of the disclosure. Other variations or modifications may occur to those skilled in the art, based on the foregoing disclosure, and are still within the scope of the present disclosure.

Claims

1. A radar level gauge for measuring a position of a material in a tank, comprising:

2. The radar level gauge according to claim 1, wherein said transceiver antenna is a plastic lens transceiver antenna; and/or the extension antenna is a circular tube-shaped extension antenna.

3. The radar level gauge according to claim 2, wherein said extension antenna comprises:

4. The radar level gauge according to claim 3, wherein an end of said waveguide remote from said transceiving antenna is formed as a chamfered cut.

5. The radar level gauge according to claim 3, wherein said extension antenna further comprises:

6. The radar level gauge according to claim 2, wherein said extension antenna is connected to said transceiver antenna by means of a screw fit.

7. The radar level gauge according to claim 6, wherein said transceiver antenna is formed with an external thread and said extension antenna is formed with an internal thread, such that the fixation of the transceiver antenna and the extension antenna is achieved by means of the matching of the internal thread of the extension antenna with the external thread of the transceiver antenna.

8. The radar level gauge according to claim 7, wherein said transceiving antenna comprises:

9. The radar level gauge according to claim 6, wherein said radar level gauge comprises:

10. The radar level gauge according to claim 9, wherein the contact position of said extension antenna with said probe is formed with a sealing structure such that said transmitting and receiving antenna is located inside said extension antenna.

11. The radar level gauge according to claim 10, wherein an end of said extension antenna near said probe is formed with an annular groove, such that a sealing structure is formed at a contact position of said extension antenna with the probe by means of a sealing ring arranged in said annular groove.

12. The radar level gauge according to claim 11, wherein said sealing ring is an O-ring.

13. The radar level gauge according to claim 2, wherein the lower end of said extension antenna is spaced from the surface of the material stored in the tank body.

14. The radar level gauge according to claim 2, wherein the axis of said extension antenna is parallel to or coincides with the axis of said transceiver antenna.

15. The radar level gauge according to claim 2, wherein the end of said extension antenna connected to the transceiving antenna has a diameter larger than the diameter of said transceiving antenna and/or larger than the diameter of the lens of said transceiving antenna.

16. The radar level gauge according to claim 2, further comprising:

17. The radar level gauge according to claim 16, wherein said angle adjustment means comprises:

a ball structure disposed in the lower socket;

18. The radar level gauge according to claim 17, wherein said angle adjustment means further comprises a fixing plate defining an upper ball socket, said upper ball socket cooperating with said spherical structure to secure said spherical structure between said fixing plate and said mounting flange when said fixing plate is secured to said mounting flange.

19. The radar level gauge according to claim 17, wherein said angle adjustment means further comprises:

20. The radar level gauge according to claim 19, wherein said locking mechanism comprises a fastening bolt, said spherical structure defining a threaded hole, said fastening bolt cooperating with said threaded hole, one end of said fastening bolt contacting said extension antenna when the fastening bolt is screwed into said threaded hole to secure said extension antenna.

21. The radar level gauge according to claim 17, wherein at least one sealing structure is provided between said extension antenna and said spherical structure for sealing a gap between said extension antenna and said spherical structure.

22. The radar level gauge according to claim 21, wherein said sealing structure is a sealing ring.

23. The radar level gauge according to claim 22, wherein an annular groove is defined in an inner wall of the receiving bore of the spherical structure, and wherein the sealing ring is disposed in the annular groove.

24. The radar level gauge according to claim 23, wherein said annular groove coincides with the axis of said receiving hole of said spherical structure.

25. The radar level gauge according to claim 2, wherein said extended antenna is provided with an air inlet hole for cooling and dust removal of said extended antenna after gas is fed into said extended antenna through said air inlet hole.

26. The radar level gauge according to claim 25, further comprising:

27. The radar level gauge according to claim 2, wherein said transceiver antenna is provided with an air inlet for providing air to said extension antenna through said air inlet.

28. The radar level gauge according to claim 2, wherein a heat sink is provided on the outside of said extension antenna to reduce the temperature of said extension antenna.

29. The radar level gauge according to claim 2, further comprising: