Fill level measuring device

Abstract

The invention relates to a measuring device neck (12) of a radar-based filling level measuring device (1) for determining a filling level profile (L(a, #)) of a filling substance (2). In this case, the measuring device neck (12) is distinguished in that waveguides (121, 121', 122, 122') for contacting antenna devices (10) are lined up internally along a contour (k1, k2) that surrounds the device neck axis (a) in a radially symmetrical manner and adjoin the device neck (12). This is advantageous first of all in terms of production of the measuring device neck (12), since the waveguides (121, 121', 122, 122') can be made together in a single-piece basic body (123) in order to be thus easily installed in the measuring device neck (12). The arrangement of the waveguides (121, 121', 122, 122') according to the invention in the measuring device neck (12) is also advantageous for the thermal management of the transmitting / receiving electronics (11) of the filling level measuring device (1), since its thermally critical radar modules (10') can be maximally spaced apart from one another.

Description

TECHNICAL FIELD

[0001] The present application relates to a fill level measuring device for determining a three-dimensional fill level profile. BACKGROUND

[0002] Corresponding field devices are applied in process automation technology to record relevant process parameters. For the purpose of recording process parameters of interest in corresponding field devices, suitable measuring principles are implemented in order to record, for example, fill levels, flow rates, pressures, temperatures, pH values, redox potentials or conductivities as process parameters. The most diverse field device types are manufactured and sold by the Endress+Hauser company.

[0003] For fill level measurement of a filling substance in a container, non-contact measurement methods have proven themselves because they are robust and low-maintenance. A further advantage of non-contact measurement methods lies in their capability to measure fill levels virtually continuously. In the field of continuous fill level measurement, radar-based measurement methods are therefore predominantly applied (in accordance with the application, the term "radar" means signals or electromagnetic waves having a frequency of between 0.03 GHz and 300 GHz). In such cases, one established measurement method is FMCW ("Frequency Modulated Continuous Wave"). A fill level measurement method based on FMCW is described, for example, in Offenlegungsschrift DE 10 2013 108490 A1.

[0004] By means of the FMCW method, it is possible to measure the distance or fill level at at least one point. In such cases, the point at which the fill level is measured depends on the orientation of the transmitting / receiving antenna, i.e. the direction of its beam lobe (due to the general reciprocity property of antennas, the characteristics of an antenna or the beam angle of a beam lobe do not depend on whether the antenna is transmitting / receiving or receiving; the term "angle" or "beam angle" means, in the context of the present application, the angle at which the beam lobe has its maximum transmission strength or reception sensitivity).

[0005] In the case of a filling substance which is a homogeneous liquid in its fill level, point-by-point fill level measurement is sufficient. In such cases, the fill level measuring device is oriented such that the beam lobe of the antenna points, for example, vertically downwards towards the filling substance, and the distance from the filling substance is determined. However, in the case of a filling substance of the solid type, such as gravel or grain, the fill level can be inhomogeneous, for example, due to a so-called bulk cargo cone, and the fill level value determined by the fill level measuring device is only limitedly accurate. It is therefore desirable, especially in such cases, to be able to determine the distance or fill level in the form of a three-dimensional fill level profile.

[0006] To do this, it is necessary for the fill level measuring device to be designed in such a way that the incoming radar signals are assigned an associated solid angle. This can be done, for example, by means of the MIMO principle ("Multiple Input Multiple Output"). Such a principle is based on the corresponding operation of an antenna arrangement consisting of a column arrangement of transmitting antennas and a row arrangement of receiving antennas in order to implement a digital beamforming of the resulting radar signals. As hardware of interest, this can be implemented, for example, by means of a correspondingly programmed MMIC ("Monolithic Microwave Integrated Circuit"). MIMO-based radar systems are described in more detail, for example, in "MIMO Radar Signal Processing" (Jian Li), 2009.

[0007] Most importantly, for the explosion protection of the fill level measuring device, a spatial separation between the active, i.e. supplied with current, transmitting / receiving unit and the passive antenna arrangement is generally required. The transmitting / receiving unit is therefore arranged outside the container, while the antenna arrangement must extend into the container and thus be exposed to the process conditions within the container. In order to implement this division, the transmitting / receiving unit is spatially separated from the antenna arrangement by a corresponding measuring device neck. In such a case, the radar signals are guided from / to the antenna arrangement to the transmitting / receiving unit through the measuring device neck. For example, for explosion protection, the measuring device neck also comprises a process seal in the given case, which seals the container opening provided for the fill level measuring device after installation, for example, using a flange.

[0008] In addition to the explosion protection requirement, the measuring device neck must also fulfill other protection functions: Depending on the application, there can be high temperatures, high pressures or hazardous gases inside the container. The measuring device neck and the flange must therefore provide a pressure seal, a temperature barrier and a gas seal. These functions together with the installation requirements require a significant distance between the transmitting / receiving unit and the antenna arrangement over which the measuring signals must be guided with as little loss as possible. In a point-by-point measuring fill level measuring device, such a distance can be bridged by a single waveguide, wherein, depending on the frequency range, coaxial lines, hollow conductors or dielectric waveguides can be applied.

[0009] In a three-dimensional mapping fill level measuring device working on the basis of digital beamforming, however, the distance between the transmitting / receiving unit and the antenna arrangement must not be for a single radar signal, but instead, as a function of the number of antennas, for a corresponding plurality of radar signals. In the case of technically and economically feasible solutions, this can require more than 200 waveguides. However, this is difficult to implement structurally and from the point of view of manufacture. SUMMARY

[0010] It is therefore an object of the present application to provide a three-dimensional mapping fill level measuring device which is easy to manufacture and which can be used under difficult process conditions.

[0011] The object is achieved by a radar-based fill level measuring device for determining a fill level profile of a filling substance in a container. To this end, the fill level measuring device comprises the following components:

[0012] - an antenna arrangement having

[0013] o a defined number of transmitting antennas by means of which, in each case, a radar signal can be transmitted to the filling substance, and

[0014] o a defined number of receiving antennas by means of which, after reflection of the radar signal on the surface of the filling substance, in each case, a reception signal can be received,

[0015] - a transmitting / receiving unit which is designed to

[0016] o generate the radar signal, for example, in accordance with the MIMO principle, and

[0017] o create a fill level profile on the basis of the reception signal, and

[0018] - a measuring device neck which is arranged between the antenna arrangement and the transmitting / receiving unit along a central device neck axis and which has

[0019] o a plurality of transmitting waveguides which correspond to the plurality of transmitting antennas and which extend in the measuring device neck parallel to the device neck axis and which connect the transmitting antennas to the transmitting / receiving unit in each case, and

[0020] o a plurality of receiving waveguides which correspond to the plurality of receiving antennas and which extend in the measuring device neck parallel to the device neck axis and which connect the receiving antennas to the transmitting / receiving unit in each case.

[0021] In such a case, the transmitting waveguides and / or the receiving waveguides can in principle be designed as hollow conductors, coaxial cables or dielectric waveguides.

[0022] The fill level measuring device according to the application is characterized by the following features, including that the transmitting waveguides are aligned along a first profile, which is preferably radially symmetrical around the device neck axis at regular intervals relative to one another, that the receiving waveguides are likewise aligned along the first profile, or along a second profile, which is likewise radially symmetrical around the device neck axis. In such a case, the receiving waveguides can also be arranged at regular intervals and alternately with the transmitting waveguides, when the receiving waveguides are also arranged along the first profile. For the case in which the receiving waveguides are arranged along the second profile, it is not essential per se whether the transmitting waveguides are arranged outside or inside the receiving waveguides with reference to the device neck axis, i.e. whether the first profile extends outside the second profile. This can depend, for example, on the implementation of the MIMO principle, or on whether more transmitting antennas or more receiving antennas are required for this purpose and the required number of transmitting and receiving waveguides.

[0023] The term "radially symmetrical profile" within the scope of the application means a profile which, with reference to the device neck axis, can be divided into at least two, equal angular segments, wherein the profile has an equal course in each equal angular segment. Radially symmetrical profiles are thus, within the scope of the application, for example, circular, elliptical or rectangular profiles. It is advantageous in this respect if the measuring device neck, the first profile and the second profile have equal radial symmetry, such as, for example, circular symmetry, with respect to the device neck axis. Advantageously, the profiles can be dimensioned with respect to the measuring device neck such that the waveguides adjoin the measuring device neck directly, or the next outwardly placed waveguide base body. In this way, there is further free space in the center of the measuring device neck for additional passages or components of the fill level measuring device.

[0024] The term "unit" in the context of the application when referring to a transmitting / receiving unit, in principle, refers to any electronic circuit which is suitably designed for the envisaged application. Thus, depending on the requirements, the unit can be an analog circuit for generating or processing corresponding analog signals. The unit can also be a digital circuit, such as an FPGA or a storage medium which cooperates with a program. In such a case, the program is designed to carry out the corresponding method steps, or the computer operations required for the application of a specific unit. In this context, different electronic units of the measuring device can potentially also use a shared physical memory, or be operated by means of the same physical, digital circuit, within the scope of the application. In particular, the transmitting / receiving unit for operating the antenna arrangement via the waveguides can be based on, for example, a corresponding number of MMICs ("Monolithic Microwave Integrated Circuits"), since, depending on the design, these MMICs are capable of carrying out the operations required for implementing the MIMO principle, such as, for example, superimposed phase shifts, amplification of signal amplitudes, etc.

[0025] In the use of MMICs, the arrangement of the application works for the transmit and receive waveguides and then advantageously for the transmit / receive units, since the distance between the individual MMICs can be maximized. Since MMICs generally have a comparatively large thermal power loss, by maximizing the distance, the thermal load between the MMICs and the thermal load within the transmit / receive units as a whole is minimized. To this end, the MMICs are arranged above the measurement device neck and along a first profile with respect to the device neck axis, in each case between one of the transmit waveguides and one of the receive waveguides, with the condition that the receive waveguides are aligned alternately with the transmit waveguides along the first profile. When the receive waveguides are not arranged along the first profile as the transmit waveguides, but instead along a second profile, the MMICs are arranged above the measurement device neck and with respect to the device neck axis between the first profile and the second profile.

[0026] The arrangement of the application for the waveguides in the measurement device neck can be implemented constructively and productively easily by means of at least one shared, in particular monolithic, base body. In such a case, the transmit waveguides and, in addition, when the receive waveguides are aligned alternately with the transmit waveguides along the first profile, the receive waveguides can also be embodied monolithically by the first base body, so that in each case a first support structure of the first base body is arranged between the individual waveguides. When the receive waveguides are not aligned along the first profile, but instead along the second profile, the receive waveguides can in turn be embodied within the measurement device neck by means of an additional second base body, so that in each case a second support structure of the second base body is arranged between the individual receive waveguides.

[0027] For the case in which the waveguides are designed as dielectric waveguides, the dielectric waveguides and the first base body or the first support structure can be made as a shared, monolithic molded part. In such a case, the receive waveguides when aligned along the second profile can in turn be embodied as dielectric waveguides, so that the receive waveguides and the second base body are made as a second, monolithic molded part. The monolithic molded part can in particular be made of PTFE, PE or PFA by means of thermoforming, injection molding, 3D printing or extrusion.

[0028] In the case where the waveguides are designed as hollow conductors, these waveguides can be implemented as at least a first basic body, in particular in conjunction with a corresponding inner section of the measuring device neck, forming the interior of the hollow conductor. When the receiving waveguides in this case are not aligned along the first profile, but instead along a second profile, these receiving waveguides in turn can be implemented as hollow conductors, such that at least a second basic body, in particular in conjunction with the outer or inner first basic body, forms the interior of the receiving hollow conductor. Moreover, in the case where the waveguides are designed as hollow conductors, the one or more basic bodies can be designed as a single-piece molded part, which in each case is produced from PTFE, PE or PFA by means of thermoforming, injection molding, extrusion or additive manufacturing, i.e. 3D printing. BRIEF DESCRIPTION OF DRAWINGS

[0029] The application will now be explained in more detail on the basis of the drawings. The drawings show the following:

[0030] Figure 1 is a radar-based filling level measuring device of the application, which is shown mounted on a container,

[0031] Figure 2 is a three-dimensional view of a basic body, by means of which a waveguide can be implemented within a measuring device neck,

[0032] Figure 3 is a first variant of a measuring device neck of a filling level measuring device,

[0033] Figure 4 is a possible arrangement of a transmitting / receiving unit for the first variant of a measuring device neck,

[0034] Figure 5 is a second variant of a measuring device neck,

[0035] Figure 6 is a possible arrangement of a transmitting / receiving unit for the second variant of a measuring device neck,

[0036] Figure 7 is a third variant of a measuring device neck,

[0037] Figure 8 is a fourth variant of a measuring device neck,

[0038] Figure 9 is a fifth variant of a measuring device neck, and

[0039] Figure 10 is a sixth variant of a measuring device neck. DETAILED DESCRIPTION

[0040] In order to illustrate the principle of radar-based filling level measurement, Figure 1A container 3 with filling material 2 is shown, and its filling level L is represented by a three-dimensional filling level distribution curve. The form of the record is as follows. In such cases, container 3 can extend to a height greater than 100m, depending on the type of filling material 2 and the application field. Moreover, the conditions within container 3 depend on the type of filling material 2 and the application field. Thus, for example, in the case of an exothermic reaction, excessively high temperature and pressure loads may occur. In the case of containing dust or flammable materials, the container must meet the corresponding explosion-proof requirements.

[0041] In order to determine the fill level distribution curve independently of the main conditions present in the container A filling level measuring device 1 is installed at a known height h above the filling material 2 at the corresponding opening on container 3. In this case, the filling level measuring device 1 is oriented and fixed so that it transmits / transmits radar signal S from antenna device 10—for example, along a vertically pointing axis a in the direction of the surface of the filling material 2. HF After being reflected off the surface of the filling material, the filling level measuring device 1 then receives the reflected radar signal R via the antenna device 10. HF Under such circumstances, transmitting and receiving radar signals S HF R HF The signal travel time between the two is related to the angular distance between the filling material level measuring device 1 and the filling material 2. The signal travel time can be determined proportionally by the filler level measuring device 1, for example, using the FMCW method or the pulse travel time method. Then, the filler level measuring device 1 can determine the distance d, for example, based on a corresponding calibration of the measured travel time. In this way, when the installation height h is set in the filler level measuring device 1, the filler level measuring device 1 can determine the filler level distribution curve according to the following formula.

[0042] d(α,β)=hL(α,β). .

[0043] Typically, the filler level measuring device 1 is connected to the upper-level unit 4, such as a process control system, via an interface, such as "PROFIBUS", "HART", or "wireless HART". In this way, the filler level distribution curve is obtained. It can be emitted, for example, to control the inflow or outflow rate of container 3 under given conditions. However, other information about the general operating status of the filling level measuring device 1 can also be conveyed.

[0044] Due to filler material 2—such as Figure 1As is schematically shown, for example, in the case of bulk goods, which do not have a planar surface, the fill level measuring device 1 is correspondingly designed to determine the fill level L in the form of a three-dimensional fill level distribution curve using digital beam pivoting . The antenna arrangement 10 thus comprises a plurality of transmitting and receiving antennas, which are arranged, for example, with reference to a substrate in the form of a column and a row at right angles to one another. In such a case, the transmitting antennas of the antenna arrangement 10 serve to transmit radar signals S HF in the direction of the filling substance 2. The corresponding reflected radar signals R HF are received by means of the receiving antennas.

[0045] The antennas of the antenna arrangement 10 are operated by the transmitting / receiving unit 11 of the fill level measuring device 1. In order to implement digital beam pivoting in the transmitting / receiving unit 11, for example, the MIMO principle can be used. In this way, the transmitting / receiving unit 11 can assign the received radar signals R HF to their solid angle a, with reference to a vertical axis a and on this basis create a three-dimensional fill level distribution curve

[0046] As is shown in Figure 1 , the antenna arrangement 10 is arranged inside the container 3, while the transmitting / receiving arrangement 11 is arranged in a separate housing outside the container 3. In order to protect the transmitting / receiving unit 11 from possible thermal loads from the inside of the container, or in order to blast-proofly isolate the inside of the container from the transmitting / receiving unit 11, the housing is spaced apart from the antenna arrangement 10 by means of a measuring device neck 12. In such a case, the device neck axis a of the measuring device neck 12, which is directed perpendicularly to the filling substance 2 and which defines the distance between the transmitting / receiving unit 11 and the container, is designed to be correspondingly long.

[0047] The high-frequency connection of the transmit and receive antennas of the antenna device 10 to the transmit / receive unit 11 takes place via a corresponding number of transmit waveguides 121, 121' and receive waveguides 122, 122', which in each case correspond to the number of transmit and receive antennas and extend parallel to the device neck axis a within the measuring device neck 12. In such a case, the transmit waveguides 121, 121' and / or the receive waveguides 122, 122' can in principle be designed as hollow conductors 121', 122' or can also be designed as dielectric waveguides 121, 122. In order for the antennas of the array arrangement to be connected correctly to the corresponding waveguides 121, 121', 122, 122', the fill level measuring device 1 can comprise a manifold in the form of a lateral redistributor structure (not shown in more detail), which is arranged between the antenna device 10 and the measuring device neck 12. In order to prevent an explosion-proof form closure of the measuring device neck 12, additionally, a gas-tight barrier can be arranged in its interior, which is based on glass or ceramic, for example, and is introduced into the measuring device neck 12 by means of welding.

[0048] In order to be able to achieve an effective angular resolution in the case of fill level measurement, it is necessary for the antenna device 10 to have a minimum number of transmit and receive antennas. In the case of a technically and economically sensible solution, this corresponds to between 16 and 200 transmit and receive channels in order to implement the MIMO principle sufficiently accurately. However, with increasing numbers of antennas, it is difficult to design and manufacture a corresponding number of waveguides 121, 121', 122, 122' which can be easily arranged within the measuring device neck 12 and which occupy as little space as possible.

[0049] In order to achieve this objective, the transmit waveguides 121, 121' according to the application are aligned at regular intervals relative to one another along a first profile k1, which is radially symmetrical around the device neck axis a of the measuring device neck 12. Likewise, the receive waveguides 122, 122' are either arranged alternately with the transmit waveguides 121, 121' along the first profile k1 or the receive waveguides 122 are arranged aligned along a second profile k2, which likewise is radially symmetrical around the device neck axis a. In such a case, the first profile k1 and in the given case the second profile k2 ideally follow the cross-sectional shape of the measuring device neck 12. This means that, in the case of a circular cross-section of the measuring device neck 12, the first profile k1 and in the given case the second profile k2 are circular.

[0050] For the manufacture, this arrangement of waveguides 121, 121', 122, 122' within the measuring device neck 12 of the application offers the advantage that the waveguides 121, 121', 122, 122' can be embodied together in a first basic body 123 and in the given case supplemented by a second basic body 124, such asFigure 2 are shown in the three-dimensional view in Figure 2 Two base bodies 123, 124 are shown in each case circularly embodied with respect to the device neck axis a along the contour k1, k2, such that the base bodies 123, 124 in each case have a cylindrical basic form along the device neck axis a. In such a case, the base bodies 123, 124 in each case have as a single-piece component alternating thickening sections 1231', 1241' and narrowing sections 1231, 1241 at regular intervals along the contour k1, k2, which define the number, positioning and geometry of the individual waveguides 121, 121', 122, 122'.

[0051] For the case in which the waveguides 121, 121', 122, 122' are dielectric waveguides 121, 122, the dielectric waveguides 121, 122 are formed by the thickening sections 1231', 1241' of the base bodies 123, 124 along the contour k1, k2. In order to be able to function as dielectric waveguides 121, 122, the base bodies 123, 124 are correspondingly produced from an electrically insulating material having a dielectric constant of at least 2. For this purpose it is possible to utilize, for example, plastics such as PTFE, PE or PFA. In the case of dielectric waveguides, the narrowing sections 1231, 1241 in each case form a support structure between the individual dielectric waveguides 121, 122.

[0052] When the waveguides 121, 121', 122, 122' are embodied as hollow conductors 121', 122', they exhibit exactly the opposite with respect to the sections 1231, 1231', 1241, 1241'. The thickening sections 1231', 1241' of the base bodies 123, 124 form in the contour k1, k2 support structure between the hollow conductors 121', 122', wherein the actual hollow conductors in the contour k1, k2 are defined by the surface of the base bodies 123, 124 in the region of the narrowing sections 1231, 1241. The hollow conductors 121', 122' are thus actually embodied as a negative of the narrowing sections 1231', 1241' in the base bodies 123, 124. In the case of such a design of the waveguides 121, 121', 122, 122' as hollow conductors 121', 122', it is necessary for the base bodies 123, 124 to have an electrically conductive surface at least in the region of the narrowing sections 1231', 1241'. For this purpose, the base bodies 123, 124 can be produced, for example, from plastic and provided with an electrically conductive coating, for example by means of sputtering or PECVD ("plasma-enhanced chemical vapor deposition"). Otherwise, the base bodies 123, 124 can be made, for example, entirely from metal.

[0053] In the three-dimensional view in Figure 2In the case of the embodiment shown in the figures, and in the case of the embodiments not yet described for the measuring device neck 11, the basic bodies 123, 124 are designed such that the waveguides 121, 121', 122, 122' have a rectangular cross section. Conversely, however, it is within the scope of the present application that there is also the option of designing the illustrated variants of the measuring device neck 11 such that the waveguides 121, 121', 122, 122' have, for example, a circular cross section.

[0054] The plastic basic bodies 123, 124 are advantageous with regard to their production in that they can be produced as a yard of goods, for example, by means of extrusion and cutting to the desired length and profile k1, k2. The basic bodies 123, 124 are then formed by winding the custom-made plastic yard of goods in the measuring device neck 12. In such a case, the measuring device neck 12 can serve as a support for at least the outer first basic body 123 in the given case, such that (depending on whether the transmitting waveguide 121, 121' or the receiving waveguide 122, 122' is placed outwardly with regard to the device neck axis a when not all waveguides 121, 121', 122, 122' are aligned on the shared profile k1) the corresponding waveguide 121, 121', 122, 122' abuts the inner side of the measuring device neck 12. The second basic body 124 and the waveguide 122, 122' are aligned along the second profile k2 in the given case and then abut the inner side of the first basic body 123.

[0055] Figure 3 This way of filling the housing neck 12 with waveguides 121, 122 is shown in a plan view of the housing neck 12 in the direction of the neck axis a. In the illustrated embodiment, the first basic body 123 forms a transmitting waveguide 121 as a dielectric waveguide, and the second basic body 124 forms a dielectric receiving waveguide 122. In such a case, the first profile k1 extends with regard to the device neck axis a outside the second profile k2, such that the first basic body 123 with the dielectric transmitting waveguide 121 is arranged with regard to the device neck axis a after assembly outside the second basic body 124 and outside the receiving waveguide 122. In such a case, the housing neck 12, the first basic body 123, i.e. the first profile k1, and the second basic body 124, i.e. the second profile k2, have a circular, radial symmetry. In such an arrangement, in which the waveguides 121, 122 are arranged outwardly and abut the inner side of the housing neck 12, it is advantageous for the fill level measuring device 1 that there is free space in the center of the measuring device neck 12 along the device neck axis a, which can then be used for possible further passageways and installed objects of the fill level measuring device 1.

[0056] Figure 4It is shown that the arrangement of the application with respect to the waveguides 121, 121', 122, 122' is also advantageous for the layout of the transmit / receive unit 11. Thus, in order to operate the antenna device 10 via the waveguides 121, 121', 122, 122', the transmit / receive unit 11 comprises high-frequency components, preferably MMICs 10', because by means of the high-frequency components, depending on the design, a plurality of radar signals S HF , R HF can be processed separately from one another. For example, by means of the MMICs 10', a defined phase shift can be applied per antenna and per waveguide 121, 121', 122, 122', the signal amplitude can be amplified, and / or the received radar signals R HF can be converted into electrical signals, etc. The MIMO principle can be implemented, for example, within the transmit / receive unit 11 in order to perform a beam steering of the transmitted radar signals S HF . The individual waveguides 121, 121', 122, 122' can be connected via suitable input coupling structures at their upper end region, for example, in the form of waveguide 121, 121', 122, 122' conical pointing towards the MMICs 10', for high-frequency transmission. Likewise towards the antenna device 10, the waveguides 121, 121', 122, 122' can be provided with corresponding input coupling structures on their lower end region.

[0057] In addition to this, in order to achieve a sufficient angular resolution for the beam steering, the number of antennas exceeds the available number of transmit and receive channels per MMIC 10' by a multiple, so that a corresponding plurality of MMICs 10' is associated with the transmit-receive unit 10. However, with increasing number of MMICs 10', the danger of an excessive thermal loading of the MMICs 10' with respect to one another increases, since each individual MMIC 10' generates a considerable thermal power loss. By the arrangement of the MMICs 10' as shown in Figure 4 above the measuring device neck 12, the mutual thermal loading of the MMICs 10' is minimized, since the possible distance between the individual MMICs 10' is maximized. As shown in Figure 4 , the MMICs 10' are arranged for this purpose between a first profile k1 and a second profile k2 with respect to the device neck axis a. Thus, the MMICs 10' are uniformly and maximally spaced apart from one another along the profiles k1, k2. For the sake of clarity, Figure 4 only one MMIC 10' is shown along the profiles k1, k2.

[0058] A second possible embodiment of the measuring device neck 12 is shown in Figure 5 . The variant shown here differs from the measuring device neck 12 described with reference to Figure 3 only the arrangement of the dielectric waveguides 121, 122. In contrast to Figure 3 ,Figure 5 The measuring device neck 12 of the embodiment shown in

[0059] The embodiment shown in Figure 4 , Figure 5 The embodiment shown in Figure 6 The MMICs 10’ in this case can be arranged in the measuring device neck 12 above the transmitting / receiving unit 11, as shown in Figure 6 In

[0060] The embodiment shown in Figure 3 and Figure 5 In contrast to the examples of the embodiments of the measuring device neck shown in Figures 7 to 10 An embodiment that differs therefrom is shown in

[0061] In the case of the embodiment in Figure 7 In this case, the first basic body 123 and the first profile k1 are embodied in such a way with respect to the measuring device neck 12 that the hollow conductors 121’, 122’ directly adjoin the inner side of the measuring device neck 12 with respect to the device neck axis a. Since the hollow conductors 121’, 122’ are embodied only by the first basic body 123, both the transmitting waveguide 121’ and the receiving waveguide 122’ are arranged alternately along the first profile k1.

[0062] Figure 8 The embodiment of the measuring device neck 12 of the application shown in Figure 7The variant shown in Fig. 3 corresponds to that shown in Fig. 2, except that in this case the receiving hollow conductor 122' is arranged on the inside of the first base body 123 and on the inside of the transmitting hollow conductor 121'. To this end, the second base body 124 is arranged on the inside of the first base body 123, such that the second base body 124, in combination with the first base body 123, forms the inner wall of the rectangular receiving hollow conductor 122'. As Figure 8 Correspondingly, in the embodiment shown in Fig. 3, three of the sides of the rectangular cross-section hollow conductor interior of the receiving hollow conductor 122' are formed by the second base body 124, while the fourth, outer side of the hollow conductor, relative to the device neck axis a, is formed by the corresponding segment of the first base body 123.

[0063] Furthermore, Figure 9 The embodiment shown in Fig. 3 corresponds to that shown in Fig. 2, except that in this case the receiving hollow conductor 122' is arranged on the inside of the first base body 123 and on the inside of the transmitting hollow conductor 121'. To this end, the second base body 124 is arranged on the inside of the first base body 123, such that the second base body 124, in combination with the first base body 123, forms the inner wall of the rectangular receiving hollow conductor 122'. As Figure 7 The variant of the measuring device neck 12 of the application shown in Fig. 3 corresponds to that shown in Fig. 2, except that the hollow conductors 121', 122' do not directly adjoin the inside of the measuring device neck 12 relative to the device neck axis a. Rather, the hollow conductors 121', 122' are embodied as a complete negative of the first base body 123. In particular in the case of this design variant, it is possible to provide the hollow conductors 121', 122' with a non-rectangular inner cross-section, such as, for example, a circular inner cross-section, in a production-friendly manner. In the case of the present embodiment, the second base body 124 is not provided. In the case of the variant of the measuring device neck 12 of the application shown in Fig. 3, the first base body 123 is embodied as a complete negative of the hollow conductor 121', 122'. In the case of the variant of the measuring device neck 12 of the application shown in Fig. 3, the first base body 123 is embodied as a complete negative of the hollow conductor 121', 122'. In the case of the variant of the measuring device neck 12 of the application shown in Fig. 3, the first base body 123 is embodied as a complete negative of the hollow conductor 121', 122'. In the case of the variant of the measuring device neck 12 of the application shown in Fig. 3, the first base body 123 is embodied as a complete negative of the hollow conductor 121', 122'. In the case of the variant of the measuring device neck 12 of the application shown in Fig. 3, the first base body 123 is embodied as a complete negative of the hollow conductor 121', 122'. Figure 9 It is advantageous in the embodiment shown in Fig. 3 that the hollow conductors 121', 122' cannot form a gap between the base bodies 123, 124 or with the interior of the measuring device neck 12, so that the high-frequency properties are not thereby degraded.

[0064] In addition to this, for cases in which the material production technology does not allow Figure 9 for the hollow conductors 121', 122' to be formed as a complete negative of the first base body 123, Figure 10 Another design variant of the measuring device neck 12 of the application is shown in Fig. 4. In this case, both the transmitting hollow conductor 121 and the receiving hollow conductor 122' are arranged along the first contour kl. In this case, however, the hollow conductors 121', 122' are formed by both the first base body 123 and the second inner base body 124. To this end, the base bodies 123, 124 are oriented relative to one another such that their narrowed segments 1231, 1241 coincide with one another and in each case have a corresponding cross-section, in order to establish the hollow conductor cross-sections accordingly.

[0065] List of reference signs

[0066] 1 filling level measuring device

[0067] 2 filling substance

[0068] 3 container

[0069] 4 superior unit

[0070] 10 antenna device

[0071] 11 transmitting / receiving unit

[0072] 12 measuring device neck

[0073] 121 transmitting waveguide

[0074] 122 receiving waveguide

[0075] 123 first base body

[0076] 124 second base body

[0077] 1231 first support structure 1241 second support structure a device neck axis d distance h installation height k1 first profile k2 second profile fill level profile R HF reflected radar signal S HF transmitted radar signal a, solid angle

Claims

1. Radar-based filling level measuring device for determining a filling level profile (L(a, β)) of a filling substance (2), comprising: - an antenna arrangement (10) having o a defined number of transmitting antennas by means of which, in each case, a radar signal (S HF ) can be transmitted to the filling substance (2), and o a limited number of receiving antennas, by means of which the radar signals (S HF ) reflected after the surface of the filling substance, in each case, a receiving signal (R HF ), - a transmitting / receiving unit (11) designed to o generating a radar signal (S HF ), and o creating the fill level profile curve (L(a, b)) on the basis of the received signals (R HF ) and - a measuring device neck (12) arranged between the antenna arrangement (10) and the transmitting / receiving unit (11) along a central device neck axis (a) and having o a plurality of transmitting waveguides (121, 121') corresponding to a plurality of transmitting antennas and extending within the measuring device neck (12) parallel to the device neck axis (a) and connecting the transmitting antennas to the transmitting / receiving unit (11) in each case, and o a plurality of receiving waveguides (122, 122') corresponding to a plurality of receiving antennas and extending within the measuring device neck (12) parallel to the device neck axis (a) and connecting the receiving antennas to the transmitting / receiving unit (11) in each case, characterized in that o the transmitting waveguides (121, 121') are aligned along a first profile (kl) which is radially symmetrical around the device neck axis (a), and o the receiving waveguides (122, 122') are aligned along the first profile (kl) or along a second profile (k2) which is likewise radially symmetrical around the device neck axis (a).

2. The fill level measuring apparatus of claim 1, wherein, For the case that the receiving waveguides (122, 122') are arranged along the second profile (k2), the transmitting waveguides (121, 121') are arranged outside the receiving waveguides (122, 122') with respect to the device neck axis (a).

3. The fill level measuring apparatus of claim 1, wherein, The measuring device neck (12), the first profile (kl) and the second profile (k2) have an equal radial symmetry with respect to the device neck axis (a).

4. The fill level measuring apparatus of claim 3, wherein, The measuring device neck (12), the first profile (kl) and the second profile (k2) have a circular symmetry with respect to the device neck axis (a).

5. The fill level measuring apparatus of claim 1, wherein, For operating the antenna arrangement (10) via the waveguides (121, 121', 122, 122'), the transmitting / receiving unit (11) comprises a corresponding number of MMICs (10'), wherein, when the receiving waveguides (122, 122') are alternately aligned with the transmitting waveguides (121, 121') along the first profile (kl), the MMICs (10') are arranged above the measuring device neck (12) and are arranged between one of the transmitting waveguides (121, 121') and one of the receiving waveguides (122, 122') in each case along the first profile (kl) with respect to the device neck axis (a), or wherein, when the receiving waveguides (122, 122') are alternately aligned with the transmitting waveguides (121, 121') along the second profile (k2), the MMICs (10') are arranged above the measuring device neck (12) and are arranged between one of the receiving waveguides (122, 122') and one of the transmitting waveguides (121, 121') in each case along the second profile (k2) with respect to the device neck axis (a). wherein the MMIC (10') is arranged above the measuring device neck (12) and between the first profile (k1) and the second profile (k2) with respect to the device neck axis (a) when the receiving waveguide (122, 122') is arranged along the second profile (k2).

6. The fill level measuring apparatus according to one of the claims 1-5, wherein, The transmitting waveguide (121, 121') and / or the receiving waveguide (122, 122') is designed as a hollow conductor (121', 122') or a dielectric waveguide (121, 122).

7. The fill level measuring apparatus according to one of the claims 1-5, wherein, The transmitting waveguide (121, 121') and the receiving waveguide (122, 122') when the receiving waveguide (122, 122') is aligned along the first profile (k1) alternatingly to the transmitting waveguide (121, 121') are embodied in a first base body (123) such that in each case a first support structure (1231, 1231') of the first base body (123) is arranged between the individual waveguides (121, 121', 122, 122').

8. The fill level measuring apparatus according to claim 7, wherein The waveguides (121, 121', 122, 122') are embodied as dielectric waveguides (121, 122) such that the dielectric waveguides (121, 122) and the first base body (123) are produced as a single-piece molded part, wherein the single-piece molded part is produced from PTFE, PE or PFA by means of thermoforming, injection molding, extrusion or additive manufacturing.

9. The fill level measuring apparatus of claim 7, wherein, The waveguides (121, 121', 122, 122') are embodied as hollow conductors (121', 122') such that at least the first base body (123) forms an interior of the hollow conductors (121', 122') in conjunction with a corresponding interior section of the measuring device neck (12).

10. The fill level measuring apparatus according to claim 8 or 9, wherein The first base body (123) is designed in terms of geometry such that the waveguides (121, 121', 122, 122') aligned along the first profile (k1) adjoin the measuring device neck (12).

11. The fill level measuring apparatus of claim 7, wherein, The receiving waveguide (122) when the receiving waveguide (122) is aligned along the second profile (k2) is embodied within the measuring device neck (12) by at least a second base body (124) such that a second support structure (1241, 1241') of the second base body (124) is arranged between the individual receiving waveguides (122, 122').

12. The fill level measuring apparatus of claim 11, wherein, The receiving waveguide (121) is embodied as a dielectric waveguide (121, 122) such that the receiving waveguide (121, 122) and the second base body (124) are produced as a single-piece molded part, wherein the single-piece molded part is produced from PTFE, PE or PFA by means of thermoforming, injection molding, extrusion or additive manufacturing.

13. The fill level measuring apparatus of claim 11, wherein, The receiving waveguide (122, 122') is embodied as a hollow conductor (122') such that at least the second base body (124) forms an interior of the receiving hollow conductor (122') in conjunction with the first base body (123).

14. The fill level measuring apparatus according to one of claims 11-13, wherein, The second base body (124) is designed in a geometric shape such that the receiving waveguides (122, 122') aligned along the second contour (k2) adjoin the first base body (123).

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