Lens arrangement for a radar antenna, antenna arrangement and radar sensor

Abstract

The present invention relates to a lens arrangement (10) for a radar antenna (28), an antenna arrangement (22) for a radar sensor (23) having a lens arrangement (10), and a radar sensor (23). The lens arrangement (10) has a flange (14) with a gap, in which a lens (12) that is permeable to a radar signal is arranged, which lens is coupled by means of a glass solder (16) in an elastomer-free manner to a mounting section (15) of the flange (14) that surrounds the gap.

Description

[0001] Lens arrangement for a radar antenna, antenna arrangement and radar sensor

[0002] The present invention relates to a lens arrangement for a radar antenna, an antenna arrangement for a radar sensor with a lens arrangement and a radar sensor.

[0003] Radar sensors are widely used today in process automation and sensor technology, for example in level sensors. However, process automation often involves media with high temperatures and / or high pressures. In addition, in some applications, these media can also be chemically aggressive, for example, corrosive or even explosive.

[0004] Existing radar sensors typically require a radio-frequency-transmitting material, such as glass, ceramic, or plastic, to spatially separate and protect the radar source from the medium. Many current approaches use elastomers or graphite for sealing between the radio-frequency-transmitting material and a mounting flange. However, elastomers are generally not designed to reliably prevent diffusion of the medium being detected into or even through the elastomer, at least not for certain media, such as ammonia or halogenated compounds containing halogens like chlorine, bromine, or similar substances.

[0005] In applications where explosion protection is paramount, glass feedthroughs, for example, can be used to create gas-tight connections. This allows the volume containing the radar source to be separated from an external space, such as the one containing the medium to be detected, in an explosion-proof manner, for example, by means of a flameproof enclosure (Ex-d). In these applications, the radio-frequency-transmitting material must have a certain thickness, typically 3 mm or more.

[0006] Previous applications have used methods such as coaxial glass feedthroughs or glass windows to seal the inner volume in which the radar source is located from the volume in which the medium is located.

[0007] Coaxial glass feedthroughs are only practical for radar frequencies up to approximately 40 GHz. If higher frequencies are required, the mechanical dimensions, and consequently the permissible tolerances, become so small that coaxial glass feedthroughs can no longer be manufactured.

[0008] In glass windows, a planar glass element is embedded within a waveguide housing (the metal shrinks onto the glass). Alternatively, so-called matched feedthroughs can be used, in which the glass and the surrounding metal have the same coefficients of thermal expansion. Glass windows in a waveguide housing can still be manufactured for frequencies up to approximately 100 GHz. The diameter of the glass embedment is only a few millimeters. In this case, the glass thickness must be ground with a precision of 5–10 pm to ensure the cancellation of reflections at the interfaces. Otherwise, the radar signal would be attenuated too much by the reflections.

[0009] If radar signals with even higher frequencies are to be used, this results in reduced waveguide dimensions, which then fall into the millimeter range, making the glass melting process increasingly complex. Maintaining the required thickness tolerance of the melted glass is then no longer possible.

[0010] There is therefore a need to eliminate or at least reduce the disadvantages of known lens arrangements for radar applications. In particular, there is a need to create a lens arrangement whose manufacturing costs are reduced compared to existing lens arrangements and whose application possibilities are broadened compared to previous approaches, while simultaneously maintaining a high degree of transmission through the lens.

[0011] The problem is solved by the subject matter of the independent claims. Advantageous embodiments are specified in the dependent claims and the following description, each of which, individually or in (sub-)combination, can represent aspects of the disclosure. According to one aspect, some embodiments of the invention relate to a lens arrangement for a radar antenna. The lens arrangement has a flange with a void in which a lens transparent to a radar signal is arranged and coupled, without elastomers, to a mounting section of the flange surrounding the void by means of a glass solder.

[0012] The glass solder-based coupling of the lens to the mounting section of the flange allows the lens to be manufactured independently of the flange. This enables the lens surface shape to be adapted to the specific radar radiation intended for use in a simple and efficient manner. Compared to previous approaches using fused glass windows, post-processing in the installed state is eliminated. Instead, the optical properties of the lens can be established and ensured independently of the coupling process before it is connected to the mounting section. The glass solder coupling of the lens to the mounting section then creates an elastomer-free seal. This makes the coupling environmentally friendly, as it eliminates the need for per- and polyfluoroalkyl substances (PFAS-free), and also ensures a durable connection.For example, this can also prevent substances from outgassing from a seal in the direction of the radar source, as is done with previous elastomer-based seals, or from diffusing through the seal in general. This allows the properties of the lens assembly to be ensured with minimal effort, while simultaneously enabling a robust and durable seal.

[0013] Optionally, the flange is designed to be coupled to an external component, such as a waveguide housing. This increases the variability of the lens arrangement with regard to compatibility with external components.

[0014] Preferably, the flange is configured according to a known fastening standard. In some embodiments, the flange may have coupling devices for connecting to external components, for example, receptacles for fasteners such as screws, threads, bolts, or the like.

[0015] In some embodiments, the connection between the lens and the mounting section is gas-tight. This is made possible in particular by the glass solder. The glass solder can preferably be made of a material that is chemically resistant (inert), at least to the intended media to be detected. This increases the tightness of the lens assembly compared to existing approaches, such as elastomer-based seals.

[0016] Preferably, the connection can be resistant to high temperatures and / or high pressures. In particular, the connection can be resistant to temperatures greater than or equal to 150°C, preferably greater than or equal to 200°C, more preferably greater than or equal to 300°C, and more preferably less than or equal to 800°C. In particular, the connection can be resistant to pressure differentials on both sides of the connection of greater than or equal to 300 kPa, more preferably greater than or equal to 700 kPa, more preferably greater than or equal to 1 MPa, more preferably less than or equal to 5 MPa, more preferably less than or equal to 10 MPa, more preferably less than or equal to 20 MPa, and more preferably less than or equal to 16 MPa, for example, for high-pressure applications.

[0017] Optionally, the connection can be diffusion-tight against foreign substances. This means that the ingress or penetration of foreign substances through the connection can be prevented. In particular, this can prevent the flow of substances through the connection. For example, a radar source located on one side of the connection can be protected from contact with a medium located on the other side of the connection.

[0018] The connection is optionally configured to provide explosion protection. Specifically, it is configured to provide explosion protection in the form of a "flameproof enclosure" (Ex-d). Explosion protection in this context means that an internal explosion, for example on one side of the connection, will not ignite an explosive medium located on the other side of the connection.

[0019] Preferably, the lens is made of glass or ceramic. This allows the lens to exhibit various desired material properties, thereby increasing the variability in its optical characteristics. Furthermore, these materials are sufficiently temperature-resistant.

[0020] In some embodiments, the lens is configured to transmit radar signals (high-frequency signals) with a frequency greater than or equal to 40 GHz essentially without reflection, preferably with a frequency greater than or equal to 70 GHz, more preferably with a frequency greater than or equal to 100 GHz, more preferably with a frequency less than or equal to 10 THz, more preferably with a frequency less than or equal to 1 THz, more preferably with a frequency less than or equal to 500 GHz, and more preferably with a frequency less than or equal to 300 GHz. Essentially without reflection here means that the proportion of reflected radar radiation striking the lens is small compared to the proportion of radiation transmitted through the lens. In particular, the proportion of reflected radar radiation is so small that reflection is negligible compared to transmission.The possible application scenarios for the lens arrangement are therefore diverse.

[0021] The lens surfaces can be treated accordingly, for example ground and / or polished, so that the surface roughness is so small that only negligible reflections occur.

[0022] In this context, high frequency refers to the frequency range of radiation that has a frequency greater than or equal to 1 GHz.

[0023] Preferably, the lens, the glass solder, and the mounting section comprise materials whose coefficients of thermal expansion differ from each other by less than 10% of the maximum coefficients of thermal expansion of the materials of the lens, the glass solder, and the mounting section, and more preferably by less than 5%. This prevents thermally induced stresses in the connection. As a result, the connection between the lens and the mounting section is resilient and durable even under potential temperature fluctuations, while simultaneously ensuring a tight seal.

[0024] Optionally, the mounting section includes a metal material. This makes the mounting section particularly resistant to external influences. For example, the mounting section is resistant to many chemical substances, especially the media to be captured.

[0025] According to a further aspect, some embodiments of the present invention also relate to an antenna arrangement for a radar sensor. The antenna arrangement comprises a lens arrangement as previously described. The antenna arrangement includes a radar antenna and a housing adapter. The housing adapter is delimited by the lens arrangement such that an internal volume is separated from an external space by the housing adapter and the lens arrangement. The radar antenna is arranged within this internal volume. The housing adapter is coupled to the glass solder and / or the mounting section of the flange of the lens arrangement. Preferably, the housing adapter is welded to the mounting section of the flange of the lens arrangement. This allows the internal volume of the housing adapter to be separated from an external space, particularly in a gas-tight, diffusion-tight, and / or explosion-proof manner.Therefore, the antenna arrangement is suitable for many different application scenarios, for example operation with / detection of explosive media, especially their fill levels.

[0026] The lens arrangement protects the radar antenna, which is located within the internal volume, from direct contact with the medium being detected. As a result, the characteristics of the radar antenna are prevented from being affected by contact with the medium.

[0027] In some embodiments, the housing adapter is coupled to the glass solder and / or the flange of the lens assembly via a soldered connection. This eliminates the need for an elastomer-based seal when coupling the housing adapter to the glass solder and / or the flange of the lens assembly. This means that the seal between the housing adapter and the glass solder and / or the flange of the lens assembly can be diffusion-tight, gas-tight, and / or explosion-proof (Ex-d). For example, the glass solder can be used simultaneously to couple the lens to the mounting section and to the housing adapter. This further improves the sealing of the antenna assembly with respect to the internal volume from the external environment.

[0028] Preferably, the housing adapter and the mounting section can be made of the same material. This helps to avoid thermal stresses. This also further increases the tightness of the internal volume compared to the external volume.

[0029] Optionally, the housing adapter features an absorber material on one of the inner surfaces facing the radar antenna. This absorber material is designed to attenuate high-frequency signals reflected from the inner surface of the lens, thereby improving the antenna's characteristics. This further enhances the antenna's radiation pattern.

[0030] In some embodiments, the radar antenna is designed in the form of a horn antenna, a planar antenna (for example, a semiconductor component such as a semiconductor chip), a parabolic antenna, a lens antenna, or an array antenna. This allows the antenna arrangement to be varied with regard to the shape of the radar antenna for many different application scenarios.

[0031] Alternatively, the lens can also be positioned adjacent to the radar antenna, at least indirectly, by means of an antenna horn on the housing adapter. The antenna horn can have a desired geometry such that the radar radiation emitted by the radar antenna is directed onto the lens in a radiation-efficient manner.

[0032] Alternatively, the lens can be positioned directly adjacent to the radar antenna. In this case, the antenna horn of the housing adapter can be omitted. This prevents any influence of a material or substance (distinct from the medium being detected) within the housing adapter on the high-frequency characteristics of the radar radiation emitted by the antenna before it reaches the lens. Typically, the lens surfaces can be convex, concave, or planar. This increases the variability of the lens arrangement, and thus the antenna arrangement, with respect to the lens's high-frequency properties.

[0033] Optionally, the lens is positioned relative to the radar antenna such that radar signals emitted by the antenna can be coupled through the lens into a waveguide. Within the waveguide, the radar signals can propagate with virtually no loss. Of course, at certain frequencies, for example, frequencies greater than or equal to 100 GHz, attenuation may still occur in the waveguide. However, "virtually no loss" in this context means that the attenuation is significantly (much) weaker than in comparable arrangements that use a coaxial cable to propagate the radar signals. The lens arrangement, and thus the antenna arrangement as well, enables the radar signal to be coupled into the waveguide even though direct contact between the radar antenna and the waveguide's inner surface is prevented.

[0034] According to a further aspect, some embodiments of the present invention also relate to a radar sensor with an antenna arrangement as described above or with a lens arrangement as described above. The radar sensor can, in particular, be configured as a level sensor.

[0035] The disclosure, as well as further advantageous embodiments and developments thereof, are described and explained in more detail below with reference to the examples shown in the drawings. These show:

[0036] Fig. 1 shows a simplified schematic representation of a lens arrangement according to one embodiment, and

[0037] Figures 2 to 6 are simplified schematic representations of an antenna arrangement of a radar antenna with a lens arrangement according to further embodiments.

[0038] The detailed description below, in conjunction with the accompanying drawings, in which identical numbers refer to identical elements, is intended to describe various embodiments of the disclosed subject matter and is not meant to represent the only embodiments. Each embodiment described in this disclosure serves only as an example or illustration and should not be construed as preferable or advantageous over other embodiments. The illustrative examples contained herein do not claim to be exhaustive and do not limit the claimed subject matter to the exact forms disclosed. Various modifications of the described embodiments are readily apparent to the person skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the described embodiments.Therefore, the described embodiments are not limited to the embodiments shown, but have the broadest possible scope of application that is compatible with the principles and features disclosed here.

[0039] All features disclosed below with reference to the exemplary embodiments and / or the accompanying figures can be combined alone or in any sub-combination with features of the aspects of the disclosure, including features of preferred embodiments, provided that the resulting combination of features is meaningful to a person skilled in the art.

[0040] For the purposes of revelation, the phrase "at least one of A, B, and C" means, for example, (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all other possible combinations when more than three elements are listed. In other words, the phrase "at least one of A and B" generally means "A and / or B," namely "A" alone, "B" alone, or "A and B."

[0041] Fig. 1 shows a simplified schematic representation of a lens arrangement 10 according to one embodiment.

[0042] The lens assembly 10 comprises a lens 12. Here, the lens 12 has a glass material suitable for transmitting radar radiation (high-frequency radiation) with a frequency of 40 GHz or higher. Other lens materials are, of course, also possible. The lens 12 has two opposing surfaces 13A, 13B, which in this embodiment have convex surface contours. In other embodiments, the surfaces 13A, 13B can also be planar or concave. Additionally, the surfaces 13A, 13B can also have different shapes.

[0043] In this case, the lens 12 is arranged such that radar radiation enters the lens 12, in particular through the first surface 13A, and exits the lens 12 through the second surface 13B (see Figs. 2 to 6). Of course, other arrangements are also conceivable.

[0044] The lens assembly 10 also has a flange 14 with a mounting section 15. In this case, the flange 14 is made of stainless steel.

[0045] Mounting section 15 is located adjacent to lens 12. Lens 12 is thus positioned in a void of flange 14. A connection is formed between lens 12 and mounting section 15 of flange 14 by means of a glass solder 16. The glass solder 16 extends from an interface 18 of mounting section 15 to a side surface 20 of lens 12. This connection between flange 14 and lens 12, via the glass solder 16, ensures a diffusion-tight and elastomer-free coupling between lens 12 and flange 14. The connection is resistant to (most) chemical substances, at least those that may come into contact with the connection during normal operation of the lens assembly 10. Furthermore, the connection between lens 12 and flange 14 meets the explosion protection standard of "flameproof enclosure" (Ex-d).The elastomer-free nature of the compound ensures that substances cannot escape (outgas) from a corresponding sealing material. In other words, the glass solder 16 is an inert material.

[0046] Figures 2 to 6 show simplified schematic representations of an antenna arrangement 22 of a radar antenna 28 with a lens arrangement 10 according to further embodiments. Only the differences between the embodiments are discussed in each case.

[0047] The antenna assembly 22 has a housing adapter 24. According to this embodiment (Fig. 2), the housing adapter 24 is coupled to the mounting section 15 of the flange 14. An internal volume 26 is formed by the connection between the lens 12 and the flange 14, as well as by the coupling of the flange 14 to the housing adapter 24.

[0048] The radar antenna 28 is arranged within the internal volume 26. Parts of the radar antenna 28 may also be arranged outside the internal volume 26. However, at least one emission element of the radar antenna 28 (front element) is arranged within the internal volume 26.

[0049] According to this embodiment (Fig. 2), the radar antenna 28 is arranged such that its radiation direction is opposite the first surface 13A of the lens 12. As a result, radar signals emitted by the radar antenna 28 strike the first surface 13A of the lens 12.

[0050] Radar antenna 28 is configured to emit radar signals at a desired frequency. In this case, radar antenna 28 is configured to emit radar signals at a frequency greater than or equal to 40 GHz.

[0051] According to this embodiment (Fig. 2), the radar antenna 28 is configured in the form of a horn antenna. Other antenna shapes for the radar antenna 28 are of course also possible.

[0052] Even though the housing adapter 24 is coupled to the mounting section 15 of the flange 14 in this case, other orientations are also possible.

[0053] According to the embodiment shown in Fig. 3, the housing adapter 24 is arranged such that its side walls are directly adjacent to the lens 12, particularly to its side surfaces 20. The coupling of the housing adapter 24 to the lens assembly 10 can also be achieved by means of the glass solder 16, as described in this embodiment. This ensures that the coupling between the housing adapter 24 and the lens assembly 10 via the glass solder 16 is diffusion-tight and elastomer-free.

[0054] The inner walls of the housing adapter 24 (typically made of metal) can also include an absorber material 30 designed to attenuate high-frequency signals reflected from the inner surface of the lens 12 (Fig. 4). This improves the antenna characteristics of the radar antenna 28. In this case, the absorber material 30 is arranged with respect to its coupling to the lens assembly 10 such that it contacts the side surfaces 20 of the lens 12.

[0055] Optionally, the housing adapter 24 can also include an antenna horn 32, which is formed between the radar antenna 28 and the lens 12 (Fig. 5). The antenna horn 32 acts as a signal guide between the radar antenna 28 and the lens 12. In particular, the antenna horn 32 ensures a defined propagation of the radar signals generated and emitted by the radar antenna 28. This improves the signal quality.

[0056] The antenna horn 32 can be integrally formed with the housing adapter 24 or can be arranged as a separate component within the housing adapter 24. The end sections of the antenna horn 32 facing the lens 12 are flush with the side surfaces 20 of the lens 12.

[0057] Of course, the radar antenna 28 can also have other forms. For example, the radar antenna 28 can be designed in the form of a semiconductor component (Fig. 6). The semiconductor component can be operated electronically in such a way that it generates radar signals which are emitted in the direction of the lens 12.

[0058] The connection between the lens 12 and the flange 14 within the lens assembly 10, and the coupling between the housing adapter 24 and the lens assembly 10, effectively isolates the internal volume 26 from the outside and from any space beyond the lens 12. This isolation can be gas-tight and / or designed as an explosion-proof enclosure (Ex-d). This prevents contact between the radar antenna 28 and any medium located beyond the lens 12, as viewed from the radar antenna 28. As a result, the radar antenna 28 is protected from all external influences and is therefore particularly durable. Advantageously, elastomers are not required for sealing, which could otherwise allow substances to diffuse out.

[0059] The lens arrangement 10, the antenna arrangement 22, and the radar sensor 23 enable, in particular, an advantageous coupling of the radar antenna 28 with a waveguide, of which the flange 14 can be a part or with which the flange 14 enables coupling. The flange 14 can therefore have corresponding coupling devices such as receptacles for connecting elements.

[0060] Naturally, the radar sensor 23 may have additional (not shown here) electronic supply circuits for the radar antenna 28 for its operation.

[0061] This revelation may refer to quantities and numbers. Unless expressly stated otherwise, such quantities and numbers are not to be considered limiting, but rather examples of the possible quantities or numbers in connection with the revelation. In this context, the term "plural" may also be used in the revelation to refer to a quantity or number. In this context, "plural" means any number greater than one, e.g., two, three, four, five, etc. The terms "about," "approximately," "near," etc., mean plus or minus 5% of the stated value.

[0062] Although the disclosure has been presented and described in relation to one or more embodiments, the person skilled in the art will be able to make equivalent changes and modifications after reading and understanding this description and the accompanying drawings.

[0063] Reference sign

[0064] 10 lens arrangement

[0065] 12 lenses

[0066] 13A first surface

[0067] 13B second surface

[0068] 14 flange

[0069] 15 Assembly section

[0070] 16 Glass solder

[0071] 18 Interface

[0072] 20 side surface

[0073] 22 Antenna arrangement

[0074] 23 radar sensor

[0075] 24 Housing adapters

[0076] 26 internal volume

[0077] 28 radar antenna

[0078] 30 Absorber material

[0079] 32 antenna horn

Claims

Patent claims 1. Lens arrangement (10) for a radar antenna (28), wherein the lens arrangement (10) has a flange (14) with a void in which a lens (12) transparent to a radar signal is arranged, which is coupled without elastomer by means of a glass solder (16) to a mounting section (15) of the flange (14) surrounding the void.

2. Lens arrangement (10) according to claim 1, characterized in that a connection between the lens (12) and the mounting section (15) is gas-tight.

3. Lens arrangement (10) according to claim 2, characterized in that the compound is diffusion-tight towards foreign substances.

4. Lens arrangement (10) according to claim 2 or 3, characterized in that the connection is configured to provide explosion protection, in particular explosion protection by means of a “pressure-resistant encapsulation”.

5. Lens arrangement (10) according to one of the preceding claims, characterized in that the lens (12) comprises a glass or a ceramic material.

6. Lens arrangement (10) according to one of the preceding claims, characterized in that the lens (12) is configured to transmit radar signals with a frequency of greater than or equal to 40 GHz substantially without reflection, preferably with a frequency of greater than or equal to 70 GHz, further preferably with a frequency of greater than or equal to 100 GHz, further preferably with a frequency of less than or equal to 10 THz, further preferably with a frequency of less than or equal to 1 THz, further preferably with a frequency of less than or equal to 500 GHz, further preferably with a frequency of less than or equal to 300 GHz, further preferably with a frequency of less than or equal to 200 GHz.

7. Lens arrangement (10) according to one of the preceding claims, characterized in that the lens (12), the glass solder (16) and the The assembly section (15) shall consist of materials whose coefficients of thermal expansion differ from each other by less than 10% of the maximum coefficients of thermal expansion of the materials of the lens (12), the glass solder (16) and the assembly section (15).

8. Lens arrangement (10) according to one of the preceding claims, characterized in that the assembly section (15) comprises a metal material.

9. Antenna arrangement (22) for a radar sensor (23) with a lens arrangement (10) according to one of the preceding claims, characterized in that the antenna arrangement (22) comprises a radar antenna (28) and a housing adapter (24) which is limited by the lens arrangement (10) in such a way that an internal volume (26) is delimited from an external space in which the radar antenna (28) is arranged by the housing adapter (24) and the lens arrangement (10), and that the housing adapter (24) is coupled to the glass solder (16) and / or the mounting section (15) of the flange (14) of the lens arrangement (10), preferably wherein the housing adapter (24) is welded to the mounting section (15) of the flange (14) of the lens arrangement (10).

10. Antenna arrangement (22) according to claim 9, characterized in that the housing adapter (24) is coupled to the glass solder (16) and / or the flange (14) of the lens arrangement (10) by means of a soldered connection.

11. Antenna arrangement (22) according to claim 9 or 10, characterized in that the housing adapter (24) has an absorber material (30) on an inner surface facing the radar antenna (28), wherein the absorber material (30) is configured to attenuate high-frequency signals reflected at the inner surface of the lens (12).

12. Antenna arrangement (22) according to one of claims 9 to 11, characterized in that the radar antenna (28) is designed in the form of a horn antenna, a planar antenna, a parabolic antenna, a lens antenna, or an array antenna.

13. Antenna arrangement (22) according to one of claims 9 to 12, characterized in that the lens (12) is arranged at a distance from the radar antenna (28), or that the lens (12) is arranged at least indirectly by means of an antenna horn (32) adjacent to the radar antenna (28), or that the lens (12) is arranged directly adjacent to the radar antenna (28).

14. Antenna arrangement (22) according to one of claims 9 to 13, characterized in that the lens (12) is arranged with respect to the radar antenna (28) such that radar signals emitted by the radar antenna (28) can be coupled into a waveguide through the lens (12).

15. Radar sensor (23) with an antenna arrangement (22) according to one of claims 9 to 14 or with a lens arrangement (10) according to one of claims 1 to 8.

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