RADAR MEASURING DEVICE

Description

[0001] The present invention relates to a radar measuring device according to the preamble of claim 1.

[0002] Various radar measurement arrangements, radar measuring devices, and methods are known in the prior art. For example, radar measurement arrangements and radar measuring devices are used in the prior art in process automation for level measurement or, more generally, for distance measurement. In order to also be able to detect moving objects, the prior art performs a separate measurement for both distance and speed determination. This can be done either with the same radar sensor or with an additional radar sensor. Corresponding radar devices are described, for example, in EP3696516, EP3693711, or DE102016217614.

[0003] Due to their extensive independence from external influences and the development of higher operating frequencies using novel semiconductor components, modern radar level gauges can reliably obtain very precise measurement results. Known radar level gauges measure the distance to a product and other reflective surfaces, hereinafter also referred to as reflectors, within a container using a pulse-time-of-flight method or an FMCW method (FMCW = Frequency Modulated Continuous Wave).

[0004] In applications in the field of automation technology, mainly optical methods and measuring arrangements are currently used.

[0005] Automation technology is a subfield of engineering that encompasses all measures for operating machines and systems without human intervention. Process automation can be considered the lowest level of automation. The goal of process automation is to automate the interaction of individual components within a plant in industries such as chemicals, petroleum, paper, cement, shipping, or mining. A wide variety of sensors are available for this purpose, specifically adapted to the unique requirements of the process industry, such as mechanical stability, resistance to contamination, and resistance to extreme temperatures and pressures.Measurement data from these sensors are usually transmitted to a control room where process parameters such as fill level, flow rate, pressure or density are monitored and settings for the entire plant can be changed manually or automatically.

[0006] Another subfield of automation technology concerns logistics automation. Using distance and angle sensors, logistics automation automates processes within a building or individual logistics facility. Typical applications for logistics automation systems include baggage and freight handling at airports, traffic monitoring (toll systems), retail, parcel distribution, and building security (access control). What these examples have in common is that the respective application requires presence detection combined with precise measurement of the size and position of an object.Known radar systems are not yet able to meet these requirements, which is why, in the known state of the art, different sensors based on optical measurement methods using lasers, LEDs, 2D cameras or 3D cameras, which detect distances according to the time-of-flight principle (ToF), are used.

[0007] A third subfield of automation technology concerns factory automation. Applications for this can be found in a wide variety of industries, such as automotive manufacturing, food production, pharmaceuticals, and packaging in general. The goal of factory automation is to automate the production of goods using machines, production lines, and / or robots, i.e., to allow it to proceed without human intervention. The sensors used and the specific requirements regarding measurement accuracy for determining the position and size of an object are comparable to those in the previous example of logistics automation. Therefore, sensors based on optical measurement methods are also typically used extensively in factory automation.

[0008] Optical sensors have dominated the fields of logistics automation, factory automation, and safety technology. They are fast and inexpensive, and can reliably determine the position and / or distance to an object due to the relatively easy-to-focus optical radiation on which the measurement is based. However, a significant disadvantage of optical sensors is their increased maintenance requirements. Even in the aforementioned areas, sensor contamination can occur after several thousand operating hours, severely impairing the measurement accuracy. Furthermore, especially when used in production lines, measurements can be affected by oil vapors or other aerosols that form mist, leading to additional contamination of the optical sensors.

[0009] In the process industry, and especially in process automation, radar measuring devices, and in particular radar level measuring devices, are reliably used under harsh conditions such as high and low temperatures, extreme pressures, dusty environments and aggressive media.

[0010] Initially, radar level gauges operating in the C-band (around 6 GHz) became established on the market and are permitted for regulatory approval. These devices have the disadvantage of being large, as the antenna size depends on the wavelength used. Therefore, radar level gauges in the K-band were developed. The K-band refers to the frequency range around 25 GHz. The antenna sizes achievable with this band are significantly reduced compared to those required for the C-band. Since 2016, the first radar level gauges, and in particular a radar level gauge for liquids, have been available that operate in the W-band (around 80 GHz). This allows for very compact antenna designs, which also permit the use of small process connections for integrating the radar level gauges into process environments.

[0011] Radio approvals for the aforementioned devices must be obtained worldwide. Various regulatory authorities have established requirements that define regionally under which conditions a radar measuring device may be approved and sold in a given country. For example, in Europe and the USA, regulations permit level-measuring radar devices operating in the C-band, K-band, W-band, and V-band. V-band radar devices operate in a frequency range around 60 GHz.

[0012] The approval process for these radar speed measuring devices considers not only the frequency range used, but also other characteristics of the radar devices, such as the emitted radio frequency power, the orientation of the radar device, and the radiation characteristics of the antenna. Furthermore, a distinction is made between whether a device is used in an enclosed space or in an open field.

[0013] The requirements for a W-band radar system approved for use in open field conditions include, for example, that the antenna must have a beamwidth of ≤8° and be mounted vertically downwards. Furthermore, the sidelobes in the range ≥60° must be attenuated by 38dB relative to the main lobe, i.e., the radiation pattern in the antenna's main direction of radiation.

[0014] A radar measuring device known from the state of the art, in this case a radar level measuring device, is in Figure 1a depicted.

[0015] The in Figure 1a The radar level gauge 100 shown essentially comprises a housing 101, a printed circuit board 106 arranged in the housing 101, and a radio frequency unit (RF unit) 105 arranged on the printed circuit board 106, containing a radar chip. The RF unit 105 includes, for example, a transmitter and receiver for radio frequency signals in the desired band.

[0016] According to the present application, a high-frequency unit is understood to be the part of a radar measuring device that generates, transmits and receives high-frequency signals.

[0017] At the in Figure 1aIn the radar level gauge 100 shown, the RF unit 105 is coupled to a horn antenna 102, at the front end of which, in the main radiation direction H, a dielectric lens 103 is arranged. The length of the horn antenna 102 is crucial for its radiation characteristics and must be designed through calculations and simulations to meet all relevant approval requirements. In particular, the beamwidth defined by the approvals and the prescribed sidelobe suppression must be mentioned. The lens 103 is located at the front of the horn antenna 102 and is designed such that the geometric length of the antenna is shorter compared to a horn antenna without a lens. In the present embodiment, a convex-convex or biconvex lens 103, i.e., a lens with two outwardly curved surfaces, is shown. This allows for a compact design.

[0018] In Figure 1b A further embodiment of a radar level measuring device 100 according to the prior art is shown, wherein, in comparison to the embodiment of the Figure 1a A plano-convex lens 301 is used.

[0019] In addition to a more compact antenna design, lenses 103 and 301 offer the advantage of acting as a barrier to the process and the process medium. The measuring electronics arranged on the circuit board 106, and in particular the RF unit 105, can be protected by lenses 103 and 301 from high and low pressures and temperatures, dust, moisture, and other environmental conditions that are detrimental to the measuring electronics.

[0020] The lenses 103, 301 are often designed to possess additional properties besides good high-frequency characteristics. These include, for example, drip cones or drip edges designed to allow condensation forming on the lens 103, 301 to drip off quickly and efficiently, or to prevent rainwater located at the side of the antenna from running directly in front of the lens.

[0021] It is possible that the horn antenna 102 is located outside the device housing 101 (see Figure 1a ) or also within (see Figure 1b ).

[0022] Another aspect that specifically concerns radar-based level measuring devices in the process industry is explosion protection.

[0023] In industrial plants, gases or dusts can often occur in concentrations that can be ignited by electrical equipment, leading to an explosion. For this reason, devices are designed and built to prevent such ignition or to ensure that ignition occurs only within the enclosure, thus preventing any impact on the surrounding environment. These devices are then classified into so-called explosion protection classes, depending on the explosion protection requirements they meet.

[0024] One way to avoid the risk of ignition within the radar level gauge 100 is in Figure 1bAs shown, the device housing 101 and the electronics contained therein are potted with a potting compound 302. This ensures that all possible cavities within the device housing 101, in which explosive gas mixtures could accumulate, are filled with the potting compound 302. This prevents the accumulation of explosive gas. The base of such a potting compound 302 can be, for example, silicone. It should also be non-conductive and harden to a certain extent after potting.

[0025] Another way to prevent ignition is to limit the power in the area of ​​a cavity to a certain level by means of appropriate circuitry.

[0026] Furthermore, a combination of both concepts is possible.

[0027] In the Figures 1a and 1bIn the radar level gauge 100 shown, there is a cavity in the horn antenna 102 that must not be filled with the potting compound 302. High-frequency signals transmitted through the horn antenna 102 would be excessively attenuated by the potting compound 302, which would negatively affect the measurement performance of the radar level gauge 100. Furthermore, the lens 103 in the horn antenna 102 would no longer function, as it is designed to be surrounded by air.

[0028] For this reason, the circuitry of the RF unit 105, which is located directly at the input of the horn antenna 102 and thus in an unforgettable area, is designed in such a way that its power is limited and the RF unit 105 only heats up to a certain degree.

[0029] A disadvantage of radar measuring devices known from the state of the art is that, in order to be legally marketed and to deliver satisfactory measurement results, they require a complex design with a horn antenna, and consequently a comparatively elaborate manufacturing process and many different components.

[0030] In the V-band, far fewer requirements are placed on antenna characteristics from a regulatory perspective. This frequency band differs from the other bands mentioned above in that other, non-level-measuring devices can also be approved. Examples include radar-based motion detectors, devices that can be operated via gesture recognition, and distance meters in the consumer electronics sector. These devices fall under the category of Short Range Devices (SRDs).

[0031] In the V-band, highly integrated radar chips are therefore increasingly available for consumer electronics. As these radar chips become more cost-effective, there is a desire to use them in radar measuring devices, and specifically in radar level gauges.

[0032] Due to the less stringent requirements for antenna radiation patterns in the V-band, antennas are used in this frequency range that would not meet the permissible radiation characteristics in other frequency bands. Planar antennas, particularly patch antennas and patch array antennas, are examples of this. These antennas offer particular advantages because they have a very flat design and can therefore be integrated into a "system on a chip," i.e., a radar system integrated on a single substrate.

[0033] Patch antennas consist of metal patches arranged on a dielectric insulating substrate; these patches can have various shapes. Patch array antennas consist of a large number of patch antennas arranged and interconnected at specific intervals. Through appropriate arrangement and control of the patch elements, patch array antennas can exhibit higher directivity compared to standard patch antennas. With a specific control method, patch array antennas are also referred to as phased array antennas. In these antennas, it is possible to modify the antenna's characteristics, and thus, in particular, its main radiation direction, by driving the individual patch elements out of phase.

[0034] Disadvantages of both antenna types include poor sidelobe suppression and still insufficient directivity.

[0035] This is where the present invention comes in.

[0036] The object of the present invention is to provide a radar measuring device with a free-radiating planar antenna.

[0037] This problem is solved by a radar device with the features of claim 1.

[0038] Advantageous embodiments and variants of the invention are described in the dependent claims and the following description. The features listed individually in the dependent claims can be combined with each other and with the features explained in more detail in the following description in any technically sensible manner, and can represent other advantageous embodiments of the invention.

[0039] A radar measuring device according to the invention, comprising a housing at least partially filled with a potting compound, a free-radiating planar antenna arranged in the housing, at least one transmitter and at least one receiver connected to the planar antenna, and a lens arranged in a main radiation direction of the planar antenna with a lens for radiation emitted by the planar antenna, is characterized in that a separating device is arranged in the housing, which is designed and arranged in such a way as to prevent the potting compound from penetrating into an area within the separating device and between the antenna and the lens.

[0040] This type of separating device allows the interior of the housing to be filled with potting compound while simultaneously accommodating a dielectric lens to focus the emitted electromagnetic waves. The area between the radiating elements and the lens, which is crucial for the planar antenna's performance, remains free of potting compound, thus preventing unpredictable fluctuations in the antenna's characteristics in this area, such as those caused by individual areas filled with potting compound.

[0041] In this context, a free-radiating planar antenna is understood to mean planar antennas, specifically patch antennas and patch array antennas, that radiate freely into air, i.e., that they do not couple into a waveguide or dielectric conductor. The electromagnetic radiation radiated by the patch elements thus passes directly into air.

[0042] In a particularly simple and cost-effective version, the separating device can be made of plastic. By designing the separating device from plastic, it can be manufactured simply and inexpensively. Furthermore, the separating device can be easily adapted to radar measuring devices of different sizes. For example, the separating device can be made of a thermoplastic material. In this case, manufacturing can be carried out particularly easily using injection molding or extrusion.

[0043] It is advantageous if the separating device is located on the rear side and surrounds the antenna radially.

[0044] In this application, terms such as "rear" and "front" are always to be understood in relation to the main radiation direction of the planar antenna used. "Rear" thus refers, in relation to the separator device, to the part of the separator device that is oriented towards the radiating radar chip or the antenna. "Front" refers to the part of the separator device that is oriented away from the radar chip or towards the lens.

[0045] The separating device is advantageously designed to radially surround the antenna and preferably completely enclose it. "Radially surrounding" is also understood to mean a situation in which the separating device is positioned away from the substrate in the main radiation direction, for example, by a spacer or seal arranged on the substrate. Crucially, the separating device must have a clear opening at its antenna-oriented end that does not overlap with any surface of the antenna.

[0046] In an advantageous further development, the separating device is designed such that it radially surrounds the lens on its front side. This ensures that the lens surface can be utilized to its maximum extent.

[0047] Advantageously, the separating device extends linearly.

[0048] In particular, the baffle can be designed to widen conically in the main radiation direction. This makes it possible to use a lens with a larger surface area extending perpendicular to the main radiation direction compared to a single surface of the antenna, while simultaneously allowing as much of the housing as possible to be filled with potting compound.

[0049] To prevent the potting compound from penetrating the area between the antenna and the lens, i.e., the interior of the separating device, it may be useful if the separating device in the main radiating device has a front and / or a rear sealing device.

[0050] In particular, the front sealing device can be arranged radially to the separating device. This allows the sealing device to seal against a part of the housing arranged radially to the separating device. This can be advantageous, for example, if the lens is integrally formed with the housing. In this case, the separating device can be positioned within a circumferential step of the housing and clamped there by the sealing device. This prevents the separating device from slipping within the housing.

[0051] Furthermore, it can be advantageous if the rear sealing device is arranged axially to the separating device, particularly between the separating device and the antenna substrate. In this configuration, the sealing device can seal against a surface of the substrate, eliminating the need for an additional sealing surface.

[0052] A particularly simple and cost-effective seal can be achieved if the front and / or rear sealing device is arranged in a groove of the separating device and is preferably designed as an O-ring. By arranging it in a groove, the sealing device can be easily positioned and held in place during assembly. The O-ring design allows the use of readily available and proven standard components.

[0053] In one variant, the separating device can be formed integrally with the housing. This design creates an arrangement in which the separating device is fixed relative to the housing. This prevents, for example, incorrect alignment of the separating device and sealing issues at the transition between the separating device and the housing. This significantly reduces the number of required components and thus simplifies the installation of the radar measuring device.

[0054] In one embodiment, both the separating device and the lens can be formed integrally with the housing.

[0055] To avoid the need for a seal at the transition between the separator device and the antenna support, the separator device can be bonded to the support by a material-bonded connection, in particular by bonding or welding. A welded connection can be produced, for example, by plastic welding, especially with a laser.

[0056] The separator can also be made of an electrically conductive plastic. Such a design ensures that unwanted side lobes of the antenna's characteristic pattern—specifically, side lobes that are not oriented towards the lens and therefore would not be focused by it—are suppressed by the separator. Furthermore, a separator made of conductive plastic attenuates the radiation from electromagnetic fields originating from directions other than the antenna's main radiation direction, thus also improving the antenna's reception.

[0057] The lens can be designed, for example, as a plano-convex lens or a Fresnel lens. A plano-convex lens has the advantage that it can be installed with its flat side facing outwards, i.e., towards the process. This allows the radar measuring device to be manufactured with a largely flat surface.

[0058] By designing the lens as a Fresnel lens, significant material savings can be achieved compared to conventional lenses. The reduced material thickness also minimizes void formation, i.e., the formation of air inclusions within the lens material. Overall, this reduces material costs and manufacturing effort for the lens. Additionally, the reduced thickness of the Fresnel lens allows for a further reduction in the overall height of the radar measuring device.

[0059] The present invention is explained in detail below with reference to exemplary embodiments and the accompanying figures. These show: Figure 1, in sub-Figures 1a and 1b, each shows an embodiment of a radar level gauge with a horn antenna according to the prior art (already discussed); Figure 2, in sub-Figures 2a to 2c, shows embodiments of planar antennas and integrated radar chips as used in consumer electronics; Figure 3 shows a first embodiment of a radar measuring device according to the present application with a conically shaped separating device; Figure 4 shows a second embodiment of a radar measuring device according to the present application with a separating device integrally formed with the housing; and Figure 5 shows a third embodiment of a radar measuring device according to the present application with a conically shaped separating device and a Fresnel lens.

[0060] In the figures, unless otherwise indicated, identical reference symbols denote identical or corresponding components with the same function.

[0061] Figure 2 Figures 2a to 2c show novel radar chips 200, as available from major semiconductor manufacturers for applications in consumer electronics in the SDR band. These radar chips 200 are designed such that a ( Figure 2a, 2c ) or several ( Figure 2b The radar chip 200 incorporates radiating patch elements designed as patch antennas 201. Furthermore, a number of other circuit components are integrated into the radar chip 200. Such radar chips can contain complete radar systems, including all circuit elements from the generation of high-frequency signals to the digitization of received signals.

[0062] The radar chips 200 have a package design that allows the chips to be automatically soldered onto a printed circuit board 106. These packages are often designed as surface-mounted devices (SMDs), in form factors such as BGA (Ball Grid Array), LGA (Land Grid Array), or QFN (Quad Flat No Leads Package).

[0063] A contact surface of the radar chip 200, which is soldered to the circuit board 106, is located on the opposite side of the patch antennas 201 integrated into the chip. The radar chips 200 and the patch antennas 201 integrated on them are designed so that the antenna radiates into free space, i.e., a vacuum or a space filled with air.

[0064] Figure 3 shows a first embodiment of a radar measuring device 300 according to the present application.

[0065] The radar measuring device 300 has a housing 306 in which a circuit board 106 with a radar chip 200 mounted on it is arranged. The mounting of the circuit board in the housing 306 is not shown in detail, but can be achieved by conventional means, e.g., slide-in rails, locking mechanisms, or screws.

[0066] For the use of the 200 series radar chips from consumer electronics in level measurement, the integrated 201 patch antennas often have insufficient directivity to achieve good measurement results. In particular, the poor focusing of the main lobe of the antenna characteristic, as well as the side lobes typical of patch antennas, result in measurements that are too unspecific.

[0067] This antenna characteristic, which is insufficient for level measurement, can be improved by using a dielectric lens 301, as described in the Figure 3The illustrated embodiment is improved in the main radiation direction H of the patch antenna 201 arranged on the radar chip 200. The lens 301 focuses the high-frequency energy emitted in the form of electromagnetic radiation, thus improving the directivity of the patch antenna 201. For this purpose, the dielectric lens 301 is arranged at a specific distance d from the patch antenna 201, such that the latter is located at the focal point of the lens 301. This distance d can be precisely determined using modern field simulation programs.

[0068] In contrast to horn antennas 102 with lenses, this method achieves a poorer sidelobe suppression, but a similarly good directivity.

[0069] In the Figure 3In the illustrated embodiment, the lens 301 is formed as an integral part of the housing 306 and is made of the same plastic as the housing 306. For this purpose, the housing 306 and the lens 301 can be manufactured together using an injection molding process. However, the lens 301 can also consist partially of a different plastic and be inserted into the housing 306 as a separate component or overmolded with the housing 306 using a two-component injection molding process. Joining the lens 301 to the housing 306 using a two-component injection molding process has the advantage that a hermetic seal can be achieved without additional seals through a material-bonded connection between the lens 301 and the housing 306.

[0070] The geometry of lens 301 depends on its material and the distance d of the patch antenna 201. Depending on the aforementioned factors and other requirements of the measurement task, lens 301 can be biconvex or plano-convex. Concave designs are also possible.

[0071] To enable use in potentially explosive atmospheres, it is necessary to design the 300 radar measuring device to be explosion-proof. As described above, this can be achieved through various measures, in particular reducing the radiated power and eliminating cavities within the 306 housing as much as possible.

[0072] To prevent the ingress of a potting compound 302 used to reduce cavities in the housing 306 into an area between the patch antenna 201 and the lens 301, the following is provided in the Figure 3In the illustrated embodiment, a separation device 303 is provided. If a radar measuring device 300 with a free-radiating patch antenna 201 and a lens integrated in the housing 306 were potted with the potting compound 302 without additional measures, the potting compound 302 would flow between the lens 301 and the patch antenna 201 and strongly attenuate the radiated RF power. Such a radar measuring device 300 would be severely limited in its measurement performance.

[0073] In the present embodiment, the separating device 303 is designed as a separate component that extends conically from the circuit board 106 to the lens 301. The separating device 303 is made of a plastic and is shown in the Figure 3In the illustrated embodiment, the separating device 303 is arranged between the circuit board 106 and the lens 301. On its rear side, the separating device 303 has a seal 304b, which in this case is designed as an O-ring. The O-ring is arranged in a groove on the end face of the separating device 303 and rests against the circuit board 106 in such a way that a transition between the circuit board 106 and the separating device 303 is sealed against the ingress of the potting compound 302.

[0074] On the front side, a seal 304a, designed as an O-ring, is also arranged in a circumferential groove of the separating device 303. The front groove is radially oriented and runs along the outside of the separating device 303. The front seal 304a is thus also arranged radially to the separating device 303 and sits between the separating device 303 and a wall section of the housing 306. In the present embodiment, a transition from the housing 306 to the lens 301 is formed with a forward-projecting step, so that the separating device sits within this step formed circumferentially around the lens 301.

[0075] The separating device thus seals the space between lens 301 and the radar chip 200, in particular the patch antenna 201, both on the front and on the back.

[0076] To ensure operation in potentially explosive atmospheres, it is essential that the circuitry of the RF unit 105, which in this embodiment is implemented by the radar chip 200, is designed such that the supplied power is limited in all cases to prevent the ignition of a potentially ignitable gas mixture in this cavity. For this reason, it is advantageous if the separating device 303 encloses only the absolutely necessary areas and components in the direction of circuit board 106, since, as already mentioned, these must be limited in terms of power and temperature. Ideally, the separating device 303 is thus designed so that the enclosed area on the rear side is minimal. On the front side, the separating device 303 surrounds the lens, which is proportionally larger than the RF unit 105.

[0077] Furthermore, from a mechanical perspective, it is important to ensure that the transitions between the separating device 303 and the circuit board 106 or housing 306 are properly sealed against the potting compound 302. This can be achieved using the O-ring seals 304a, 304b. Alternatively, other seals 304a, 304b can be used, which, for example, can be directly injection-molded onto the separating device 303. The circuit board 106 has a sealing surface so that the separating device 303 can fit tightly against it. No electronic components are located in this area. It should be noted that other electronic components besides the radar chip, e.g., for controlling the radar chip 200 or for downstream signal processing, are not shown in the figures but are nevertheless present.

[0078] The present disconnect device 303 differs from a horn antenna 102, as known from the prior art, in that it can be made entirely of plastic. A horn antenna 102, on the other hand, requires at least one metallic conductive layer. Another difference lies in the signal input. With a horn antenna 102, the high-frequency signal must be fed in a specific way. This is usually done via a metallic or metallized waveguide 104, in which the high-frequency signal generated by the circuit is excited. However, such a signal input cannot be implemented with the radar chips 200 with integrated patch antennas 201 used here, since this would require a direct electrical connection between the antenna horn 102 and a ground plane of the patch element. This is not provided for in the radar chips 200 used.

[0079] In a Figure 4In the alternative embodiment shown, the separating device 401 is designed as an integral part of the housing 402. In this embodiment, the separation point between the housing 402 and the separating device 401 is eliminated, and the front seal 304a can be omitted.

[0080] In a first variant, the isolation device 303 is transparent to high-frequency signals, so that it has no functionality from a high-frequency technical point of view.

[0081] In an alternative version, the separating device 303 is made of a conductive plastic. Besides its primary function of creating a potting compound-free space 305 between the radar chip 200 and the lens 301, this plastic also serves to reduce unwanted side lobes. While these are generally not critical from a regulatory perspective, they can generate interference in the radar signal, impairing measurement reliability. The conductive plastic converts the RF energy radiated towards the separating device 303 into heat, thereby attenuating the side lobes. This also reduces the energy of reflections not originating from the main lobe, thus minimizing their impact on the received signal.

[0082] In another embodiment, as described in Figure 5As shown, lens 301 is not designed as a bi- or plano-convex lens, but as a Fresnel step lens 501, also known as a Fresnel lens 501. Since the refraction of the wavefronts only occurs at the interfaces between air and lens material, the core principle of the Fresnel lens is that the interior of the lens can be segmented and removed, as it theoretically contributes nothing to the functionality of the lens.

[0083] One advantage of this design is the reduced lens volume. This makes it easier to manufacture using a plastic injection molding process. A problem with bulky, solid injection-molded plastic parts is the formation of voids. These cavities, also known as shrinkage cavities, form as the molded material cools and have a significant negative impact on the lens's high-frequency functionality. The high-frequency signals are refracted unevenly at these cavities, leading to defocusing and thus performance losses. The risk of shrinkage cavities increases with the volume-to-surface area ratio of the injection-molded object. This risk is significantly reduced in a Fresnel lens because the volume-to-surface area ratio is considerably lower compared to a conventional 301 convex lens.

[0084] Another advantage of a Fresnel lens is that the device housing 502 can be made flatter overall. The height of the housing 502 is defined, among other things, by the thickness of the lens and the distance d between the lens and the radar chip 200. The reduced height of the Fresnel lens 501 compared to a convex lens therefore has a significant impact on the overall height h of the device. Compact designs have proven advantageous in practice. A further benefit is reduced material costs.

[0085] The present invention relates not only to radar level gauges operating in the V-band, but can also be applied to other radar measuring devices in the V-band. Furthermore, there are other frequency bands that permit such a technique, for example in the range around 122 GHz. Reference symbol list

[0086] 100, 300 Radar measuring device 101, 306, 402 Housing 102 Horn antennas 103, 301 Lens 104 Waveguide 105 High-frequency unit 106 Circuit board, PCB 200 radar chip, 201 patch antenna 302 Potting compound 303, 401 Separating device 304a Seal 304b Seal 305 Potting compound-free space 501 Fresnel lens 502 Device housing dDistance hBuilding height HMain radiation direction

Claims

1. Radar measuring device (100, 300) with a housing (101, 306, 402) at least partially filled with a potting compound (302), a general-diffuse planar antenna arranged in the housing (101, 306, 402), at least one transmitter and at least one receiver that are connected to the planar antenna, and a lens (103, 301) arranged in a main emission direction H of the planar antenna [for] radiation emitted from the planar antenna, characterized in that a separating apparatus (303, 401) is arranged in the housing (101, 306, 402) and is designed and arranged in such a way that a penetration of the potting compound (302) into an area within the separating apparatus (303, 401) and between the antenna and the lens (103, 301) is prevented.

2. Radar measuring device (100, 300) according to Claim 1, characterized in that the separating apparatus (303, 401) is made from a plastic.

3. Radar measuring device (100, 300) according to any of the preceding claims, characterized in that the separating apparatus (303, 401) is designed to radially surround the planar antenna at the rear.

4. Radar measuring device (100, 300) according to any of the preceding claims, characterized in that the separating apparatus (303, 401) is designed to radially surround the lens (103, 301) at the front.

5. Radar measuring device (100, 300) according to any of the preceding claims, characterized in that the separating apparatus (303, 401) is designed to widen conically in the main emission direction H.

6. Radar measuring device (100, 300) according to any of the preceding claims, characterized in that the separating apparatus (303, 401) has a front and / or a rear sealing apparatus in the main emission [direction].

7. Radar measuring device (100, 300) according to Claim 6, characterized in that the front sealing apparatus is arranged radially to the separating apparatus (303, 401).

8. Radar measuring device (100, 300) according to Claim 6 or 7, characterized in that the rear sealing apparatus is arranged axially to the separating apparatus (303, 401), in particular between the separating apparatus (303, 401) and a carrier for the antenna.

9. Radar measuring device (100, 300) according to any of the Claims 6 to 8, characterized in that the front sealing apparatus and / or the rear sealing apparatus is arranged in a groove of the separating apparatus (303, 401) and is preferably designed as an O-ring.

10. Radar measuring device (100, 300) according to any of the Claims 1 to 5, characterized in that the separating apparatus (303, 401) is designed integrally with the housing (101, 306, 402).

11. Radar measuring device (100, 300) according to any of the preceding claims, characterized in that the separating apparatus (303, 401) is sealingly connected, in particular glued, to a carrier for the antenna.

12. Radar measuring device (100, 300) according to any of the preceding claims, characterized in that the separating apparatus (303, 401) is made from an electrically conductive plastic.

13. Radar measuring device (100, 300) according to any of the preceding claims, characterized in that the lens (103, 301) is designed as a plano-convex lens or as a Fresnel lens (501).