EP4297181A1 - Dielectric waveguide for propagating high frequency waves - Google Patents

Abstract

The invention relates to a waveguide, in particular a dielectric waveguide (20), for propagating high-frequency waves, and a dielectric waveguide arrangement (28). The dielectric waveguide (20) has a first section (21) with a substantially uniform cross section, and a second section (22) having a larger cross section than the first section (21). The dielectric waveguide arrangement (28) has a waveguide (20) and a holder (25) which at least partially encompasses the dielectric waveguide (20).

Description

Field of invention

The invention relates to a waveguide, in particular a dielectric waveguide, for propagating high-frequency waves, e.g. radar waves, a waveguide arrangement, a manufacturing method and a use.

background

Waveguides are suitable and/or designed to transmit high-frequency waves (HF waves), for example from an HF generator to an antenna. For at least some waveguides - e.g. from a certain length of the waveguide - it may be necessary to arrange one or more holders and/or other support devices on the waveguide, e.g. to support the waveguide. However, in at least some waveguides, e.g. in some types of dielectric waveguides, these mounts can lead to the HF waves escaping from the waveguide and/or to spurious reflections in the HF signal.

Summary

It is the object of the invention to provide a device which can help reduce spurious reflections in the HF signal. This task is solved by the subject matter of the independent patent claims. Further developments of the invention result from the subclaims and the following description.

• einen ersten Abschnitt mit einem im Wesentlichen gleichförmigen Querschnitt, und
• einen zweiten Abschnitt, aufweisend einen größeren Querschnitt als der erste Abschnitt.

One aspect relates to a dielectric waveguide for propagating high frequency waves, the waveguide comprising:

• a first section having a substantially uniform cross section, and
• a second section having a larger cross section than the first section.

The dielectric waveguide can be designed as a plastic filament with a cross-sectional area of basically any shape, which in at least some embodiments can be rectangular or round. The dielectric waveguide can be suitable or designed to transmit a high-frequency signal, in particular to transmit it with low loss. For example, a dielectric waveguide can have a cross-sectional area between 0.25 mm ² and 8 mm ² . The cross-sectional area can depend on the frequency of the waveguide to be transmitted. In general, a dielectric waveguide with a relatively small cross-sectional area - which may correspond to the first section - can have a relatively lower signal attenuation than a waveguide with a relatively larger cross-sectional area. However, a waveguide with a larger cross-sectional area - which can correspond to the second section - can be less sensitive to external influences and objects (such as holders) that are in the immediate vicinity of the waveguide.

Therefore, the dielectric waveguide described here can be designed as a first section with a substantially uniform cross section over a majority of its route, and as a second section or expansion over at least some parts of its route, the second section having a larger cross section than the first section . The second section or the expansion can be particularly suitable for arranging, for example, fastening elements (such as brackets) thereon. As a result, a compromise can advantageously be achieved between low signal attenuation, which particularly characterizes the first section or sections, and low sensitivity to interference, which is typical for the second section. Furthermore, interference from the waveguide holders can be minimized and the radar system can be adjusted in terms of its ringing behavior (interference reflections in the antenna area and/or Close range of the antenna) can be improved. Furthermore, the measurement reliability in close ranges can be increased.

The production of such dielectric waveguides with expansion can be realized using various production processes. For example, production by means of injection molding, in particular plastic injection molding, has proven to be very efficient and/or cost-effective.

In some embodiments, the cross-sectional area of the second section is larger than the cross-sectional area of the first section by a factor of 5 to 80, in particular by a factor of 10 to 50, for example by a factor of 15 to 30. This has proven to be a particularly efficient compromise between low signal attenuation and low interference when arranged with (e.g.) brackets.

In some embodiments, a transition between the first section and the second section is designed to be stepped, oblique and/or rounded. The transition on the left and right sides of the second section can be designed the same. The design of the transition can depend on the manufacturing process chosen.

In some embodiments, the dielectric waveguide has a cross-sectional area between 0.25 mm and 8 mm, in particular between 0.3 mm and 3 mm. The diameter of the cross section can, for example, depend on the frequency and/or the shape of the cross section (e.g. rectangular) as well as on the plastic used.

In some embodiments, the dielectric waveguide includes a plurality of second sections, and the second sections are spaced between 10 mm and 300 mm. The distances between the expansions of the dielectric waveguide can be equidistant from one another, but non-uniform distances are also possible. The distances between the expansions can be significantly larger than the length of the expansions. This can advantageously emphasize the low signal attenuation.

In some embodiments, the cross section of the first section and/or the second section is elliptical, in particular round, rectangular, in particular square, and/or polygonal, in particular as an equilateral polygon. The design of the cross section can depend on the selected measurement frequency, the plastic used, the selected manufacturing process and/or on the objects arranged on it (e.g. fasteners or holders).

In some embodiments, the dielectric waveguide has a DK value (relative permittivity ε _r ) between 2 and 5 and/or loss factors tan(δ) between 0.00001 and 0.1.

In some embodiments, the dielectric waveguide consists of or has a plastic, in particular a material from a group including polyetheretherketone, PEEK, polytetrafluoroethylene, PTFE, perfluoroalkoxy, PFA, polyvinylidene fluoride, PVDF, and / or rigid polyethylene (high density polyethylene ), HDPE. The plastics mentioned can in particular tolerate high process temperatures and/or be resistant to a large number of chemicals. In addition, from a high-frequency perspective, these plastics can have small DK values (2 ≤ ε _r ≤ 3.5) and loss factors (0.00001 ≤ tan(δ) ≤ 0.1).

One aspect relates to a method for producing a dielectric waveguide as described above and/or below by means of injection molding, in particular by means of plastic injection molding. This has proven to be very efficient and/or cost-effective.

One aspect relates to a dielectric waveguide assembly that includes a dielectric waveguide as described above and/or below, and a holder that at least partially comprises the dielectric waveguide and/or is otherwise arranged on the waveguide. Alternatively, a combination of a series of dielectric waveguides and waveguides is possible.

In some embodiments, the holder is made of stainless steel, in particular 316L stainless steel, and/or of a plastic, in particular hard polyethylene, HDPE, or has this material. The material of the holder can advantageously have a lower DK value than the dielectric waveguide. Advantageously, less signal is coupled out at the holders and the signal attenuation is not significantly worsened. This can also contribute to a low sensitivity to interference of the waveguide arrangement.

In some embodiments, the holder is connected to the dielectric waveguide by means of a positive, non-positive and/or material connection. The holder can be detachably connected to the dielectric waveguide.

One aspect relates to a use of a dielectric waveguide as described above and/or below or a dielectric waveguide arrangement as described above and/or below for propagating radar waves, in particular for frequencies between 70 GHz and 500 GHz, for example between 100 GHz and 300 GHz.

One aspect relates to a use of a dielectric waveguide as described above and/or below or a dielectric waveguide arrangement as described above and/or below for level measurement, topology determination and/or limit level determination.

It should also be noted that the various embodiments described above and/or below can be combined with one another.

For further clarification, the invention is described using the embodiments shown in the figures. These embodiments are only to be understood as an example and not as a limitation.

Short description of the characters

Fig. 1

schematisch ein Radargerät gemäß einer Ausführungsform;

Fig. 2a - 2e

einen Zusammenhang zwischen Leiterquerschnitten eines Wellenleiters und einer elektrischen Feldverteilung;

Fig. 3a - 3c

schematisch einen Wellenleiter und eine Wellenleiteranordnung gemäß einer Ausführungsform;

Fig. 4a - 4b

schematisch eine Wellenleiteranordnung gemäß einer weiteren Ausführungsform;

Fig. 5a - 5b

schematisch eine Wellenleiteranordnung gemäß einer weiteren Ausführungsform.

This shows:

Fig. 1

schematically a radar device according to one embodiment;

Fig. 2a - 2e

a relationship between conductor cross sections of a waveguide and an electric field distribution;

Fig. 3a - 3c

schematically a waveguide and a waveguide arrangement according to one embodiment;

Fig. 4a - 4b

schematically a waveguide arrangement according to a further embodiment;

Figs. 5a - 5b

schematically a waveguide arrangement according to a further embodiment.

Detailed Description of Embodiments

Fig. 1 shows schematically a radar device 10, for example for level measurement technology in process or factory automation, according to one embodiment. The radar device 10 has sensor electronics 14 which is arranged in a housing 12. The sensor electronics 14 can, for example, have a generator or transmitter and/or a receiver of high-frequency waves (HF waves). A connection between the sensor electronics 14 and an antenna system 18 for transmitting the HF waves can be realized, for example, by means of a dielectric waveguide 20. This can be particularly advantageous for applications involving high process temperatures, in which a certain spatial distance between sensor electronics 14 and antenna system 18 may be required so that, for example, the electronic components of sensor electronics 14 can be operated in their specified temperature range. The dielectric waveguide 20 may be supported by one or more holders 25. The holder 25 can at least partially include the dielectric waveguide 20. The holder 25 can be connected to the dielectric waveguide 20 by means of a positive, non-positive and/or material connection. The holder 25 can be detachably connected to the dielectric waveguide 20. The dielectric waveguide 20 can form a dielectric waveguide arrangement 28 with the holder 25 and, optionally, with further components - for example a housing 27. The waveguide arrangement 28 can, for example, have a length between 1 cm and 50 cm exhibit. Such a dielectric waveguide arrangement 28 can advantageously have low signal attenuation compared to a waveguide, for example at frequencies >100 GHz. Furthermore, a dielectric waveguide arrangement 28 can be produced relatively easily and inexpensively, for example as a plastic injection molded part. On the other hand, the production of waveguides for frequencies > 100 GHz can be technically demanding, time-consuming and therefore cost-intensive.

The dielectric waveguide 20 may have one or more first sections 21 with a substantially uniform cross section. Furthermore, the dielectric waveguide 20 may have one or more second sections 22. The second section or sections 22 have a larger cross section (or an expansion) than the first section 21. A transition 23 is arranged between the first section 21 and the second section 22, which can be designed, for example, in a step-shaped, oblique and/or rounded manner . The holder(s) 25 are preferably arranged on the second section 22. This can be advantageous because an optimized electric field distribution in and/or on the dielectric waveguide 20 can be achieved. In particular, interference reflections in the HF signal can be reduced when the HF waves are transmitted using the dielectric waveguide 20. As a result, a compromise can advantageously be achieved between low signal attenuation, which particularly characterizes the first section or sections 21, and low sensitivity to interference, which is typical of the second section 22.

Figs. 2a and 2b show a connection between conductor cross sections of a waveguide 20 (see e.g Fig. 1 ) and an electric field distribution in and on the waveguide 20. The scale of Fig. 2c represents an attenuation of the electric field strength. The brighter, the lower the attenuation. The waveguides 20 from Figs. 2a and 2b have - without limiting generality - a rectangular cross section (shown in black). The waveguide 20 points from Fig. 2b a larger cross section than the waveguide 20 of Fig. 2a .

In the representation of Fig. 2a It becomes clear that the waveguide 20 has an (elliptical) maximum of the electric field strength (shown brightly, corresponding to the scale of Fig. 2c ) within the waveguide 20. Furthermore, a maximum of the electric field strength can be determined above and below the waveguide 20, ie outside the waveguide 20. This means that the waveguide 20 can release electrical energy to the environment when one of the areas of high field strength (eg above and below the waveguide 20) is touched by an object or comes close to the waveguide 20. Such an object can be, for example, a holder for the waveguide 20. The release of electrical energy into the environment can, for example, lead to increased attenuation and/or spurious reflections in the HF signal. However, as long as no object touches or comes close to the waveguide 20, a waveguide 20 with a small cross-section has lower signal attenuation than a waveguide 20 with a larger cross-section (such as in Fig. 2b shown). This is particularly true at higher frequencies, for example above 70 GHz or above 100 GHz.

The representation of Fig. 2a shows that with a larger cross section of a waveguide 20, smaller areas of high field strength occur outside the waveguide 20. Therefore, interference from an external object is less than with a waveguide 20 with a smaller cross section. However, the signal attenuation is higher than with a waveguide 20 with a smaller cross section (such as in Fig. 2a shown).

It is therefore particularly advantageous to provide a waveguide 20 which has longer regions with a relatively smaller cross section (first sections 21), for transmission with low signal attenuation, and has dedicated regions with a relatively larger cross section (second sections 22). , which are particularly suitable for arranging brackets on them, for example, with relatively less signal interference from these objects. This advantageously allows a compromise to be achieved between low signal attenuation, which particularly characterizes the first section or sections 21, and low sensitivity to interference, which is typical for the second section 22. The further figures show implementation examples for such a waveguide 20 and/or a waveguide arrangement 28.

The examples of Figs. 2d and 2e show a connection between conductor cross sections of a waveguide 20 (see e.g Fig. 1 ) and the electric field strength along the waveguide center in the horizontal direction in another representation. A distance from a center of the waveguide 20 in the y direction is plotted on the abscissa of the diagrams 51 and 52, and a relative intensity of the electric field strength along the center of the waveguide is plotted on the ordinate. The waveguide has a width (or cross section) b. The areas between the dashed lines describe the electric field strength within the waveguide 20. This illustration also shows that the electric field strength outside the dielectric waveguide with a smaller cross section b (see Fig. 2d ) is significantly higher than a waveguide with a larger cross section b (see Fig. 2e ). This means - as explained above - that the waveguide 20 can release electrical energy to the environment when one of the areas of high field strength (eg to the left and right of the waveguide 20) is touched by an object or comes close to the waveguide 20.

Fig. 3a - 3c schematically show a waveguide 20 and a waveguide arrangement 28 according to an embodiment. The waveguide 20 from Fig. 3a has a plurality of first sections 21 and two widenings or second sections 22. The second sections 22 have a step-shaped transition 23 on both sides. In Fig. 3a Only the pure dielectric waveguide 20 with two cross-sectional expansions 22 is shown. These expansions or second sections 22 can be positioned at a certain distance from one another. The longer the waveguide, the more expansions 22 can be provided.

Fig. 3b shows a cross section through a waveguide arrangement 28, which has a waveguide 20, as shown in, for example Fig. 3a is shown. The waveguide 20 can be made, for example, from hard polyethylene (HDPE). The same reference numbers denote the same or similar components as in Fig. 3a . Furthermore, the waveguide arrangement 28 has the Fig. 3b two holders 25, which are arranged in the area of the second sections 22. These can be used, for example, to properly seal the waveguide in its housing position and hold accordingly. The holders 25 can, for example, advantageously be made of a metallic material, such as stainless steel 316L, and/or of plastics, for example. The material of the holder can advantageously have a lower DK value than the dielectric waveguide. This can contribute to a low sensitivity to interference of the waveguide arrangement.

In one embodiment, the waveguide can be held using (hard) foam, e.g. Rohacell. This can be advantageous for applications with lower requirements for temperature resistance and/or mechanical stability.

Fig. 3c shows a perspective view of a waveguide arrangement 28 as in Fig. 3b . The waveguide arrangement 28 has a waveguide 20 and holders 25 which are arranged in the area of the second sections 22.

4a and 4b show schematically a waveguide arrangement 28 according to a further embodiment, each in a perspective view ( Fig. 4a ) and in cross section ( Fig. 4b ). The waveguide arrangement 28 has a waveguide 20 and three holders 25 which are arranged in the area of the second sections 22. The second sections 22 and the holders 25 are arranged equidistantly; However, other distances are also possible. Like in particular Fig. 4b becomes clear, the transitions 23 are designed obliquely. However, step-shaped and/or rounded designs are also possible. The transitions 23 from the first sections 21 of the waveguide 20 to the widenings 22 at the holding points are realized in this example with suitable tapers (tapers, or a transition, for example a widening, from the small conductor cross-section to the large conductor cross-section). The interference reflections or the influence of the holders can thereby advantageously be reduced again.

Figs. 5a - 5b show schematically a waveguide arrangement 28 according to a further embodiment, each in a perspective view ( Fig. 5a ) and in cross section ( Fig. 5b ). The same reference numbers designate the same or similar components as in the previous figures. The waveguide arrangement 28 has one waveguide 20 and three Holders 25 which are arranged in the area of the second sections 22. The second sections 22 and the holders 25 are not arranged equidistantly.

List of reference symbols

10

Radar device

12

Housing

14

Sensor electronics

18

Antenna system

20

dielectric waveguide

21

first section of the waveguide

22

second section of the waveguide

23

crossing

25

bracket

27

Housing

28

dielectric waveguide arrangement

51, 52

Diagrams

Claims (16)

Dielectric waveguide (20) for propagating high-frequency waves, the waveguide (20) comprising: a first section (21) with a substantially uniform cross section, and a second section (22) having a larger cross section than the first section (21). Dielectric waveguide (20) according to claim 1,
wherein the cross-sectional area of the second section (22) is larger by a factor of 5 to 80, in particular by a factor of 10 to 50, for example by a factor of 15 to 30, than the cross section of the first section (21). Dielectric waveguide (20) according to claim 1 or 2,
wherein a transition (23) between the first section (21) and the second section (22) is step-shaped, oblique and / or rounded. Dielectric waveguide (20) according to one of the preceding claims,
wherein the cross section of the first section (21) has a cross sectional area between 0.25 mm and 8 mm, in particular between 0.3 mm and 3 mm. Dielectric waveguide (20) according to one of the preceding claims,
wherein the dielectric waveguide (20) has a plurality of second sections (22), and the second sections (22) have a spacing of between 10 mm and 300 mm. Dielectric waveguide (20) according to one of the preceding claims,
wherein the cross section of the first section (21) and/or the second section (22) is elliptical, in particular round, rectangular, in particular square, and/or polygonal, in particular as an equilateral polygon. Dielectric waveguide (20) according to one of the preceding claims,
wherein the dielectric waveguide (20) has a DK value between 2 and 5, in particular between 2.5 and 3.5, and / or has loss factors between 0.00001 and 0.1. Dielectric waveguide (20) according to one of the preceding claims,
wherein the dielectric waveguide (20) consists of a plastic or has this material, in particular a material from a group which includes polyetheretherketone, PEEK, polytetrafluoroethylene, PTFE, perfluoroalkoxy, PFA, polyvinylidene fluoride, PVDF, and / or rigid polyethylene, HDPE . Method for producing a dielectric waveguide (20) according to one of the preceding claims by means of injection molding. Dielectric waveguide arrangement (28), comprising: a dielectric waveguide (20) according to one of the preceding claims, and a holder (25) which at least partially encompasses the dielectric waveguide (20). Dielectric waveguide arrangement (28) according to claim 10, wherein the holder (25) consists of stainless steel, in particular 316L stainless steel, and/or of a plastic, in particular HDPE, of a foam, in particular Rohacell, or has this material, wherein the material of the holder (25) has a lower DK value than the dielectric waveguide (20). Dielectric waveguide arrangement (28) according to claim 10 or 11, wherein the holder (25) is connected to the dielectric waveguide (20) by means of a positive, non-positive and/or material connection, and/or wherein the holder (25) is detachably connected to the dielectric waveguide (20). Dielectric waveguide arrangement (28) according to claim 10, 11 or 12,
wherein the holder (25) and the dielectric waveguide (20) are arranged in a housing (27). Radar device (10), in particular radar level measuring device, with a dielectric waveguide (20) according to one of claims 1 to 8 or a dielectric waveguide arrangement (28) according to one of claims 10 to 13. Use of a radar device (10) according to claim 14 for level measurement, topology determination and/or limit level determination. Use of a dielectric waveguide (20) according to one of claims 1 to 8 or a dielectric waveguide arrangement (28) according to one of claims 10 to 13 for propagating radar waves, in particular for frequencies between 70 GHz and 500 GHz, for example between 100 GHz and 300 GHz .

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