Measuring device with cylindrical monopole antenna

Abstract

Measuring device, configured as a level gauge, pressure gauge, temperature gauge, or flow meter for process automation in industrial or private environments, comprising a sensor device for acquiring level, pressure, temperature, or flow measurement data and a cylindrical monopole antenna for transmitting the measurement data to an external receiver. A battery and / or one or more circuit boards are arranged inside the monopole antenna.

Description

Field of the invention

[0001] The present invention relates to measuring instrument technology in industrial and private environments. In particular, the present invention relates to a measuring device with a cylindrical monopole antenna, a cylindrical monopole antenna, and the use of a cylindrical monopole antenna in a measuring device. Technical background

[0002] In measuring devices for process automation in industrial or private environments, and especially in standalone sensors, the arrangement of the antenna inside the housing often results in a reduction in transmission and reception characteristics, resulting in higher energy consumption for wireless communication. In particular, energy storage devices and their cabling, or additional circuit boards, due to their relatively large dimensions, often prove to be disruptive when located close to the antenna, thus impairing its radiation behavior. Furthermore, SMT chip antennas cannot achieve particularly high efficiencies on the lower mobile radio frequencies when the circuit boards are too small or circular. Summary

[0003] Against this background, it is an object of the present disclosure to provide a measuring device which has good transmission properties when transmitting the measurement data to an external receiver.

[0004] This object is achieved by the features of the independent patent claims. Further developments of the invention emerge from the subclaims and the following description of embodiments.

[0005] A first aspect of the present disclosure relates to a measuring device configured as a level measuring device for process automation in industrial or private environments. It comprises a sensor device configured to acquire level measurement data, as well as a cylindrical monopole antenna used to transmit the level measurement data to an external receiver. One or more batteries or charge storage devices and / or a circuit board and / or a radar antenna horn are arranged in the interior of the cylindrical monopole antenna.

[0006] The measuring device can be designed as a field device in automation technology. It can have a plastic housing or a metal housing with a housing opening and an electronics unit arranged inside the housing, including at least one circuit board. The antenna is designed to transmit and receive electromagnetic waves with at least one predetermined wavelength. The antenna is oriented such that it is designed to transmit electromagnetic waves through the housing or the housing opening and to receive electromagnetic waves to be received from the direction of the housing or the housing opening. The antenna can be used to establish a wireless communication connection between the electronics unit and a transmitting / receiving unit arranged outside the housing of the field device.

[0007] The term "process automation in industrial environments" can be understood as a branch of technology that includes measures for operating machines and systems without human intervention. One goal of process automation is to automate the interaction of individual components of a plant in the chemical, food, pharmaceutical, petroleum, paper, cement, shipping, or mining industries. A variety of sensors can be used for this purpose, which are specifically adapted to the specific requirements of the process industry, such as mechanical stability, insensitivity to contamination, extreme temperatures, and extreme pressures. Measured values ​​from these sensors are usually transmitted to a control room, where process parameters such as fill level, limit level, flow rate, pressure, or density are monitored, and settings for the entire plant can be changed manually or automatically.

[0008] A sub-area of ​​process automation in the industrial environment concerns the logistics automation of plants and the logistics automation of supply chains. With the help of distance and angle sensors, processes inside or outside a building, or within a single logistics facility, are automated in the field of logistics automation. 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 the aforementioned examples have in common is that the respective application requires presence detection in combination with precise measurement of the size and location of an object.For this purpose, sensors based on optical measuring methods using lasers, LEDs, 2D cameras or 3D cameras that measure distances according to the time of flight (ToF) principle can be used.

[0009] Another sub-area of ​​process automation in the industrial environment concerns factory / production automation. Applications for this can be found in a wide variety of industries, such as automotive manufacturing, food production, the pharmaceutical industry, 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 run it without human intervention. The sensors used here and the specific requirements regarding measurement accuracy for detecting the position and size of an object are comparable to those in the previous example of logistics automation.

[0010] The terms used in the claims should be construed to give them the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article "a" or "the" in introducing an element should not be construed to exclude a plurality of elements. Similarly, the mention of "or" should be construed to include a plurality of elements, so that the mention of "A or B" does not exclude "A and B" unless it is clear from the context or the preceding description that only one of A and B is intended.Furthermore, the phrase "at least one of A, B, and C" should be understood as one or more elements from a group of elements consisting of A, B, and C, and should not be interpreted as requiring at least one of each of the listed elements A, B, and C, whether A, B, and C are related as categories or otherwise. Furthermore, the mention of "A, B, and / or C" or "at least one of A, B, or C" should be interpreted to include each individual unit of the listed elements, e.g., A, each subset of the listed elements, e.g., A and B, or the entire list of elements A, B, and C.

[0011] A further aspect of the present disclosure relates to a measuring device configured as a pressure measuring device for process automation in industrial or private environments. This device also comprises the elements described above (sensor device, cylindrical monopole antenna).

[0012] A further aspect of the present disclosure relates to a measuring device configured as a temperature measuring device for process automation in an industrial or private environment and comprising a sensor arrangement for acquiring temperature measurement data and the cylindrical monopole antenna described above.

[0013] A further aspect of the present disclosure relates to a measuring device which is configured as a flow measuring device for process automation in an industrial or private environment and which comprises a sensor device for acquiring flow measurement data and the cylindrical monopole antenna described above.

[0014] The cylindrical monopole antenna exhibits greater efficiency than conventional arrangements. By integrating the battery or other components inside the antenna, the impact of interference, reflections, and bulkheading on the antenna's radio characteristics is reduced.

[0015] According to a further embodiment of the present disclosure, the cylindrical monopole antenna tapers conically at its end facing the process and / or at its end facing away from the process.

[0016] According to a further embodiment of the present disclosure, the measuring device comprises a high-frequency circuit board which is arranged outside the cylindrical monopole antenna and which is configured to generate the antenna signal to be radiated.

[0017] According to another embodiment of the present disclosure, the cylindrical monopole antenna is mounted or attached to the RF circuit board.

[0018] According to another embodiment of the present disclosure, the RF circuit board represents the opposite pole of the cylindrical monopole antenna.

[0019] According to a further embodiment of the present disclosure, the inner diameter of the cylindrical monopole antenna corresponds to the outer diameter of the battery or battery pack.

[0020] According to a further embodiment of the present disclosure, the measuring device further comprises a contact pin arranged concentrically to the cylindrical monopole antenna, which connects the positive pole of the battery to the RF circuit board.

[0021] According to a further embodiment of the present disclosure, the measuring device comprises a circuit board arranged in the interior of the cylindrical monopole antenna. The battery may be mounted on this circuit board.

[0022] According to a further embodiment of the present disclosure, the measuring device comprises a plastic housing in which the cylindrical monopole antenna and the sensor device are arranged. Preferably, the plastic housing is closed and sealed.

[0023] A further aspect of the present disclosure relates to a cylindrical monopole antenna, as described above and below, configured to transmit measurement data from a measuring device to an external receiver, wherein a battery and / or one or more circuit boards are arranged in the interior of the cylindrical monopole antenna.

[0024] Another aspect of the present disclosure relates to the use of a cylindrical monopole antenna described above and below in a measuring device for process automation in an industrial or private environment for transmitting measurement data from the measuring device to an external receiver.

[0025] Embodiments of the present disclosure are described below with reference to the figures. Where the same reference numerals are used in the following description of the figures, they denote identical or similar elements. The representations in the figures are schematic and not to scale. Short description of the characters Fig. 1 shows several measuring devices and an external receiver according to one embodiment. Fig. 2 shows a cross-sectional view through a measuring device according to an embodiment. Fig. 3 shows a cross-sectional view through a measuring device according to another embodiment. Fig. 4 shows a front view and a side view of a measuring device according to an embodiment in cross-sectional representation. Fig. 5 shows a top view of a high-frequency circuit board according to an embodiment. Fig. 6 shows the simulation of the achievable adaptation of a cylindrical monopole antenna of a measuring device according to an embodiment. Detailed description of embodiments

[0026] Fig. 1 shows several measuring devices 100, 400 and an external receiver 300 in the form of a display and control unit.

[0027] The external receiver 300 can communicate with the measuring devices 100, 400 via the cloud 500, or directly, and receive measurement data from them.

[0028] The measuring devices are designed, for example, as a level measuring device 100, a flow measuring device 100, a pressure measuring device 400, or a temperature measuring device 100, and all have a cylindrical monopole antenna 200 and a sensor device 101. In the case of a pressure measuring device, the sensor device 101 is a pressure measuring cell; in the case of a level measuring device, for example, it is a radar chip with an antenna; in the case of a temperature measuring device, it is a temperature measuring cell; and in the case of a flow measuring device, it is a flow measuring cell.

[0029] The level measuring device can, for example, be designed as a level radar measuring device and emit a radar signal of 80 GHz or above (or below).

[0030] Fig. 2 shows a cross-sectional view of a measuring device 100, 400 according to one embodiment. The antenna 2 used is a monopole. It is not designed as a wire antenna, but as a cylinder with a sufficient cavity in which components such as batteries or their cabling or circuit boards are accommodated. Because the interior is field-free (Faradey cage), the components located there cannot influence the radiated or received field of the antenna. In order for the antenna to achieve maximum efficiency at the mobile radio frequencies used for e.g., NB-IoT, LTE-M, LPWAN, and LoRaWAN, modifications compared to the classic monopole are necessary.

[0031] As the diameter of the monopole's cylindrical base plate increases, the capacitive loading causes the antenna to detune, especially in the higher frequency bands. Therefore, the lower part of the antenna is designed as a truncated cone, which can also be used as a parameter to improve matching. A short-circuit connection from the antenna housing to the ground of the RF circuit board 10 is also provided, which, as with known PIF antennas, provides an additional option for impedance matching. This ground connection also routes the negative pole of the battery to the RF circuit board without interference. The positive pole of the battery is routed coaxially inside the RF feed and therefore has no noticeable influence.

[0032] An important aspect is the integration of components, such as batteries and circuit boards, into the interior of antenna 2 in order not to disturb the radiation properties of the antenna and to achieve the highest possible efficiency of the antenna.

[0033] In principle, the measuring devices described are self-contained sensors, i.e., battery-operated measuring devices whose recorded values ​​are transmitted to the control center via a radio interface at the desired time interval. The antenna efficiency has a significant influence on battery life, because if the antenna efficiency is too low, significantly more power is required for radio communication.

[0034] Fig. Figure 2 shows a first embodiment of a measuring device in which the required components are housed in a dust- and watertight plastic housing 1. The batteries and their cabling are advantageously integrated in the cylindrical cavity of the antenna 2, as these are exclusively conductive parts with a corresponding influence on the electromagnetic fields of the antenna. In the embodiment shown, five batteries 4 are combined in a battery holder 5 and connected by cable connectors or otherwise to the circuit board 6 resting on the cone rim. Depending on requirements and available height, additional circuit boards 6' can also be installed inside the cylinder. This also applies to the measuring cells 3 and 3' (not described in detail), which can be located inside and / or outside the antenna 2. The measuring cell 3' can, for example, have a radar antenna horn.The batteries can also be arranged in the measuring cell 3, which is located outside the cylindrical cavity. The monopole antenna 2, which tapers to a conical shape due to the capacitive load, is placed in the center of the RF circuit board 10 and is fixed to the RF circuit board by a plastic ring 7 with supports, while simultaneously being supported on the housing 1.

[0035] Fig. Figure 3 shows a minimalist embodiment in which a single D-size battery 4 (monocell) is installed. Advantageously, the diameter of the antenna 2 is designed such that the battery 4 is supported on the cylindrical wall of the monopole 2. A circuit board 8 located inside the antenna receives the positive pole of the battery 4 and conducts the pole, shielded, to the RF circuit board 10 via a contact pin 9. The circuit board 8 can also incorporate simple circuit components such as reverse polarity protection or current limiting, thus reducing malfunctions.

[0036] All components for radio communication are located on the RF circuit board 10. The RF circuit board 10 also represents the opposite pole of the monopole.

[0037] The negative terminal of the battery is connected to the conductive cover 5 via a spring contact 11, which is screwed into the thread of the antenna cylinder, for example, and thus simultaneously clamps the battery in place. Other mounting options are also possible; the electrical contact between battery 4 and antenna 2 is important.

[0038] The antenna 2 is mounted in the center of the RF circuit board 10 via a plastic ring with supports, maintaining a constant distance from the housing 1. This results in a circular antenna pattern in the azimuthal direction.

[0039] On the lower side, the antenna 2 tapers conically toward the RF circuit board 10 to reduce the capacitive load to ground. Varying the lower diameter of the truncated cone can simultaneously improve the matching in the used frequency bands.

[0040] Fig. Figure 4 shows two more detailed views of the connection between the antenna 2 and the RF circuit board 10. The contact pin 9 from the positive terminal 4' of the battery 4 is inserted coaxially through the feed 13 directly into the RF circuit board 10. For insulation from ground, either air is used inside the cylindrical feed 13, or a plastic body 15 is inserted into the cavity of the feed 13. This provides better support for the contact pin 9 and simultaneously hermetically shields the battery 4 inside the antenna against external influences.

[0041] The transmitted signal reaches the antenna via two connection pins 14. A shorting plate 12 is located beneath the conical base of antenna 2, which, similar to conventional PIF antennas, creates a current path to the circuit board's ground. The negative battery terminal is routed to the circuit board via contact pin 16, providing another option for improving antenna tuning.

[0042] In order to achieve optimal adaptation of the antenna for, for example, the lower and upper LTE frequency bands, it has proven advantageous to connect the contact pin 16 of the short-circuit plate 12 via a short-circuited line.

[0043] Fig. Figure 5 shows the connection of the antenna to the circuit board separately. It shows a line 17 that is short-circuited to ground holes 19. The length of this line 17 to contact pin 16 determines the effective impedance with which the antenna is matched.

[0044] Alternatively, an inductance can be placed between contact pin 16 and ground and adjustment can be made by varying the inductance value.

[0045] Opposite is a 50-ohm line 18, which carries the high-frequency signals to the antenna. This is done via the two contact pins 14, which are connected to the connecting ring 20. The hole for receiving the contact pin 9 is visible inside the connecting ring 20. If multiple signals are to be routed into the interior of the antenna, this is possible in principle. In this case, an insulating body can be provided that accommodates the connecting pins and is pressed together with them into the feed cylinder.

[0046] Fig. 6 shows a simulation for a Fig. 2, in a closed PTFE housing with a total diameter of 93 mm and a total length of 150 mm, for which the achievable adaptation was calculated using a field simulator. The result of the simulation is the Fig.6, which exhibits a very good S11 value of ≤ -14 dB (VSWR ≤ 1.5) at the band edges. This allows antenna efficiencies of more than 90 percent to be achieved in both bands.

Claims

[1] Measuring device, designed as a level measuring device for process automation in industrial or private environments, comprising: a sensor device (101, 3) arranged to detect fill level measurement data; a cylindrical monopole antenna (2, 200) arranged to transmit the level measurement data to an external receiver (300); wherein a battery (4) and / or a circuit board (6) and / or a radar antenna horn (3') is arranged in the interior of the cylindrical monopole antenna. [2] Measuring device, configured as a pressure measuring device (400) for process automation in an industrial or private environment, comprising: a sensor device (101, 3) arranged to detect pressure measurement data; a cylindrical monopole antenna (2, 200) arranged to transmit the pressure measurement data to an external receiver (300); wherein a battery (4) and / or a circuit board (6) is arranged in the interior of the cylindrical monopole antenna. [3] Measuring device, configured as a temperature measuring device (100) for process automation in an industrial or private environment, comprising: a sensor device (101, 3) arranged to detect temperature measurement data; a cylindrical monopole antenna (2, 200) arranged to transmit the temperature measurement data to an external receiver (300); wherein a battery (4) and / or a circuit board (6) is arranged in the interior of the cylindrical monopole antenna. [4] Measuring device, configured as a flow meter (100) for process automation in an industrial or private environment, comprising: a sensor device (101, 3) arranged to detect flow measurement data; a cylindrical monopole antenna (2, 200) arranged to transmit the flow measurement data to an external receiver (300); wherein a battery (4) and / or a circuit board (6) is arranged in the interior of the cylindrical monopole antenna. [5] Measuring device according to one of the preceding claims, wherein the cylindrical monopole antenna (2, 200) tapers conically at its end facing or facing away from the process. [6] Measuring device according to one of the preceding claims, further comprising: an RF circuit board (10) which is arranged outside the cylindrical monopole antenna (200) and which is configured to generate the antenna signal to be radiated. [7] Measuring device according to claim 6, wherein the cylindrical monopole antenna (2, 200) is placed on the RF circuit board (10). [8] Measuring device according to claim 6 or 7, wherein the RF circuit board (10) represents the opposite pole of the cylindrical monopole antenna (200). [9] Measuring device according to one of the preceding claims, wherein the inner diameter of the cylindrical monopole antenna (2, 200) corresponds to the outer diameter of the battery (4). [10] Measuring device according to one of claims 4 to 7, further comprising: a contact pin (9) arranged concentrically to the cylindrical monopole antenna (2, 200), which connects the positive pole of the battery (4) to the RF circuit board (10). [11] Measuring device according to one of the preceding claims, further comprising: a printed circuit board (6) which is arranged in the interior of the cylindrical monopole antenna (2, 200) and on which the battery rests. [12] Measuring device according to one of the preceding claims, further comprising: a plastic housing (1) in which the cylindrical monopole antenna (2, 200) and the sensor device (101, 3) are arranged. [13] Cylindrical monopole antenna (2, 200), arranged for transmitting measurement data of a measuring device to an external receiver (300), wherein a battery (4) and / or a printed circuit board (6) and / or a radar antenna horn (3') is arranged in the interior of the cylindrical monopole antenna. [14] Use of a cylindrical monopole antenna (2, 200) according to claim 13 in a measuring device for process automation in an industrial or private environment for transmitting measurement data from the measuring device to an external receiver (300).

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