Microwave transmission arrangement, communication and / or measurement system and radar level gauge system

Abstract

Microwave transmission devices, communication and / or measurement systems, and radar level gauge systems are disclosed. One microwave transmission device includes: a conductive hollow waveguide having a first waveguide portion, a second waveguide portion between the first waveguide portion and a first end of the hollow waveguide, and a conductive transition surface forming a transition between the first and second waveguide portions; and a microwave circuit board including a dielectric carrier and a first conductor pattern on a first side of the dielectric carrier, the first conductor pattern including a patch for radiating or receiving microwave signals within a predefined wavelength range and a first ground plane surrounding the patch, wherein the first ground plane of the microwave circuit board is in conductive contact with the first end of the hollow waveguide and extends into the cross-sectional region of the second waveguide portion to define at least one conductive pocket together with the second waveguide portion of the hollow waveguide and the transition surface.

Description

Technical Field

[0001] This invention relates to microwave transmission devices, communication and / or measurement systems, and radar level gauge systems. Background Technology

[0002] To transmit high-frequency microwaves from and to microwave transceiver circuit systems, a transition from the microwave circuit board to a conductive hollow waveguide is known. Such a transition can be achieved using a so-called quarter-wave reverse short circuit, but this can make it particularly difficult, especially at relatively high frequencies, to integrate the microwave circuit board with lower-frequency circuit boards to accommodate other electronic components such as signal processing circuit systems.

[0003] Therefore, a solution has been proposed that does not require a quarter-wave reverse short circuit, but uses a patch and at least partially around the ground plane of the patch to achieve microwave coupling with the waveguide.

[0004] The aim is to provide this microwave coupling in a manner suitable for use in environments subject to EX restrictions, particularly those relating to so-called intrinsically safe operation. The concept of intrinsically safe operation is defined by relevant specifications and means that even in the worst-case scenario, normal signals or voltages that might occur under fault conditions should not be able to cause ignition. Examples of intrinsically safe specifications are IEC 610079-0 and IEC 610079-11. Applications that could benefit from this include, for example, tank metering and microwave communications in industrial sites or gas stations. Summary of the Invention

[0005] In view of the above, the overall objective of the present invention is to provide an improved microwave transmission device, specifically a microwave transmission device suitable for use in environments subject to EX restrictions.

[0006] Therefore, according to one aspect of the present invention, a microwave transmission device is provided, comprising: a conductive hollow waveguide configured to guide a microwave signal within a predefined wavelength range along a signal propagation path defined by the hollow waveguide in a predefined propagation mode, the hollow waveguide having: a first waveguide portion having a first waveguide cross-sectional area; a second waveguide portion between the first waveguide portion and a first end of the hollow waveguide, the second waveguide portion having a second waveguide cross-sectional area larger than the first waveguide cross-sectional area; and a conductive transition surface of the hollow waveguide forming a transition between the first waveguide portion and the second waveguide portion; and a microwave circuit board including a dielectric carrier and a first conductor pattern on a first side of the dielectric carrier, the first conductor pattern including a patch for radiating or receiving microwave signals within the predefined wavelength range and a first ground plane surrounding the patch, wherein the first ground plane of the microwave circuit board is in conductive contact with the first end of the hollow waveguide and extends into the cross-sectional area of ​​the second waveguide portion to define at least one conductive pocket together with the second waveguide portion of the hollow waveguide and the transition surface.

[0007] The first waveguide cross-section region is a plane perpendicular to the signal propagation path, and the second waveguide cross-section region is located in a plane perpendicular to the signal propagation path.

[0008] The first ground plane extending into the cross-sectional region of the second waveguide portion to define at least one conductive pocket together with the second waveguide portion of the hollow waveguide and the transition surface should be understood to mean that the first ground plane—in addition to being in conductive contact with the first end of the hollow waveguide—also exists in the region of the microwave circuit board on the first side of the hollow waveguide defined by the hollow waveguide at the first end. A gap may exist between the outer periphery of the patch and the edge of the first ground plane, and the first ground plane may extend from this edge and at least to the first end of the hollow waveguide, and at least partially extends beyond the first end of the hollow waveguide.

[0009] The inventors have found that existing microwave transmission devices—which use patches and a ground plane at least partially surrounding the patches to achieve microwave coupling with a waveguide—fail to combine efficient microwave energy transfer with intrinsic safety. In particular, the inventors have found that the distance between the patch and the hollow waveguide does not become sufficiently large to meet the requirements of relevant standards.

[0010] In view of this discovery, the present invention is based on the understanding that by configuring the hollow waveguide and the first ground plane in such a way that at least one conductive pocket is formed at the transition between the microwave circuit board and the hollow waveguide, a sufficient distance can be achieved between the patch and the hollow waveguide, while simultaneously enabling efficient transfer of microwave energy between the patch and the hollow waveguide. Through a proper configuration of such conductive pockets (or multiple conductive pockets), the distance between the patch and the hollow waveguide can be increased while maintaining acceptable microwave energy transfer capability. The inventors have also surprisingly discovered that the configuration with one or more conductive pockets can be configured in a way that increases the tolerances for positioning the microwave circuit board and the hollow waveguide relative to each other, which facilitates cost-effective mass production of the microwave transmission device according to embodiments of the present invention, as well as systems or devices including the microwave transmission device.

[0011] It should be noted that the exact configuration of one or more conductive bags will generally depend on the layout of the microwave circuit board and / or the wavelength range, and those skilled in the art will be able to obtain the appropriate conductive bag configuration using, for example, readily available simulation tools.

[0012] According to one embodiment, the transition surface of the hollow waveguide can extend in a direction perpendicular to the signal propagation path by a distance corresponding to at least 0.4 times the center wavelength of a predefined wavelength range. This means that the depth of at least one conductive pocket becomes a distance corresponding to at least 0.4 times the center wavelength of the predefined wavelength range.

[0013] Simulations have shown that such a minimum depth of at least one conductive bag may be advantageous for the transmission of microwave signals from the patch to the hollow waveguide.

[0014] Furthermore, the transition surface of the hollow waveguide can advantageously extend in a direction perpendicular to the signal propagation path by a distance less than 0.6 times the center wavelength of the predefined wavelength range. This means that the depth of at least one conductive pocket becomes less than 0.6 times the center wavelength of the predefined wavelength range.

[0015] Simulations have shown that such a maximum depth of at least one conductive bag may be advantageous for the transmission of microwave signals from the patch to the hollow waveguide.

[0016] Various simulation results are in complete agreement with the theory of the so-called half-wavelength choke, and confirm that at least one conductive bag can be configured to act as a virtual short-circuit wall, such that microwave signals propagating from the patch will effectively see the hollow waveguide with the first waveguide cross-section region when they enter the hollow waveguide at the first end of the hollow waveguide.

[0017] According to various embodiments, the microwave transmission device may further include a microwave transceiver circuit system having an output terminal for providing microwave signals generated by the microwave transceiver circuit system and an input terminal for receiving microwave signals; and a patch may be connected to at least one of the output terminal and the input terminal.

[0018] A "transceiver" can be a functional unit capable of transmitting and receiving microwave signals, or it can be a system that includes separate transmitter and receiver units.

[0019] According to an embodiment, the microwave transmission device may be advantageously included in a communication and / or measurement system, which further includes a processing circuit system coupled to and configured to control the microwave transceiver circuit system to provide microwave signals and / or perform signal processing on microwave signals received by the microwave transceiver circuit system.

[0020] According to one particular embodiment, the microwave transmission device may advantageously include a radar level gauge system for determining the fill level of a product in a tank, the radar level gauge system further comprising: an antenna coupled to a hollow waveguide of the microwave transmission device for radiating an electromagnetic emission signal from the microwave transmission device to the surface of the product, and for returning an electromagnetic reflection signal generated by reflection of the electromagnetic emission signal at the surface to the microwave transmission device; and a processing circuit system coupled to a microwave transceiver circuit system included in the microwave transmission device and configured to determine the fill level based on the time relationship between the emitted signal and the reflected signal.

[0021] For all implementations, it should be noted that the processing circuitry system can be provided as a single device or as several devices working together.

[0022] In summary, the present invention therefore relates to a microwave transmission device comprising: a conductive hollow waveguide having a first waveguide portion, a second waveguide portion between the first waveguide portion and a first end of the hollow waveguide, and a conductive transition surface forming a transition between the first waveguide portion and the second waveguide portion; and a microwave circuit board including a dielectric carrier and a first conductor pattern on a first side of the dielectric carrier, the first conductor pattern including a patch for radiating or receiving microwave signals within a predefined wavelength range and a first ground plane surrounding the patch, wherein the first ground plane of the microwave circuit board is in conductive contact with the first end of the hollow waveguide and extends into the cross-sectional region of the second waveguide portion to define at least one conductive pocket together with the second waveguide portion of the hollow waveguide and the transition surface. Attached Figure Description

[0023] These and other aspects of the invention will now be described in more detail with reference to the accompanying drawings, which illustrate the presently preferred embodiments of the invention, in which:

[0024] Figure 1 An example application of a microwave transmission device according to an embodiment of the present invention is illustrated schematically;

[0025] Figure 2 This is a schematic side view of an example application of a microwave transmission device according to an embodiment of the present invention, in the form of an exemplary radar level gauge system; and

[0026] Figures 3A to 3C A microwave transmission apparatus according to an exemplary embodiment of the present invention is illustrated schematically. Detailed Implementation

[0027] In this detailed description, various embodiments of the microwave transmission device according to the present invention are discussed primarily with reference to a radar level gauge system.

[0028] It should be noted that this does not limit the scope of the invention, which also includes microwave transmission devices for other applications such as communication systems, for example, microwave links that can be used, for example, in 5G communication systems.

[0029] Figure 1 An industrial site 1, such as a processing industry, is schematically illustrated, including a refinery or similar factory. Figure 1 The industrial site 1, schematically illustrated, includes storage tanks 3 and various processing equipment 5. Depending on the type of industry, hazardous environments may exist at the industrial site 1, thus requiring certification of the equipment used at the site 1 according to applicable standards. Appropriately, at least some of the equipment used at the site 1 must meet the relevant intrinsic safety requirements, meaning that the equipment is certified as not capable of causing ignition in hazardous environments. Examples of applicable standards for intrinsic safety are IEC 610079-0 and IEC 610079-11.

[0030] Examples of equipment that can be advantageously configured to meet intrinsic safety requirements at an industrial site 1 may include Figure 1 The microwave link 7 and the radar level gauge system 9 are schematically indicated. Such systems according to embodiments of the invention share the common feature that they each include a microwave transmission device for transmitting microwave signals between the transceiver circuitry and the antenna. As is known to those skilled in the art, various specifications may differ for the devices used in the microwave link 7 and the radar level gauge system 9, respectively. For example, the antenna configuration may be specifically adapted to the environment in which the antenna is positioned. However, the microwave transmission devices used in various applications may have substantially the same configuration.

[0031] Figure 2 This is a schematic side view of an example application of a microwave transmission device according to an embodiment of the present invention, in the form of an exemplary radar level gauge system 9.

[0032] like Figure 2 As conceptually indicated, the radar level gauge system 9 includes a microwave transceiver circuit system 11, a microwave transmission device 13 including a hollow waveguide 15, an antenna 17, a processing circuit system 19, a communication circuit system 21, and a process connection in the form of a flange 23.

[0033] The microwave transceiver circuit system 11 has combined microwave output and input ports 25 for providing microwave signals generated by the microwave transceiver circuit system 11 and for receiving microwave signals. For example... Figure 2 As schematically indicated, the microwave transceiver circuit system 11 also has a measurement data interface 27 coupled to a corresponding measurement data interface 29 of the processing circuit system 19. The processing circuit system 19 further has a communication interface 31 coupled to a corresponding communication interface 33 of the communication circuit system 21.

[0034] In the operation of the radar level gauge system 9, the processing circuit system 19 controls the microwave transceiver circuit system 11 to generate and transmit microwave signals. The microwave transmission signals are provided by the microwave transceiver circuit system 11 to the microwave transmission device 13, which then transfers the microwave transmission signals to the antenna 17. (Briefly referenced...) Figure 1 Antenna 17 radiates microwave transmission signal S onto the surface 4 of product 6 in storage tank 3. T Microwave transmission signal S T At least in part as microwave reflected signal S R The microwave signal S is reflected back to antenna 17. R The microwave signal reaches antenna 17 and is guided by hollow waveguide 15, and microwave transmission device 13 transmits the microwave reflected signal S. R The signal guided by the hollow waveguide 15 is converted to the signal by the microwave circuit board ( Figure 2 The signal carried by the stripline (not shown) is returned to the microwave transceiver circuit system 11. Based on the microwave transmitted signal S... T With microwave reflected signal S R Based on the time relationship between the two, the processing circuit system 19 determines the fill level of product 6 in storage tank 3 in a manner known per se. A communication signal indicating the determined fill level is transmitted to an external host by the communication circuit system 21.

[0035] In microwave link 7, distance determination is not required. Instead, data can be encoded on the transmitted signal in a manner known to those skilled in the art, and data can be retrieved by decoding the received signal.

[0036] Figures 3A to 3C A microwave transmission device 13 according to an exemplary embodiment of the present invention is schematically shown. Figures 3A to 3C The microwave transmission device 13 schematically shown in the diagram can be used in various systems, such as Figure 1 The microwave link 7 and radar level gauge system 9 are included.

[0037] First refer to Figure 3A , Figure 3A This is an exploded view of a microwave transmission device 13, which includes a conductive hollow waveguide 15 and a microwave circuit board 34. The hollow waveguide 15 is configured to guide microwave signals within a predefined wavelength range along a signal propagation path defined by the hollow waveguide 15 in a predefined propagation mode. The predefined wavelength range may be, for example, 77 GHz to 81 GHz, and the predefined propagation mode may be, for example, TE 10, but other wavelength ranges and / or propagation modes are feasible and may be advantageous depending on the application.

[0038] like Figure 3A As instructed in the document, but Figure 3B As better illustrated, the hollow waveguide 15 has a first waveguide portion 35 and a second waveguide portion 37. The first waveguide portion 35 has a first waveguide cross-sectional area, and the second waveguide portion 37 has a second waveguide cross-sectional area larger than the first waveguide cross-sectional area. The first waveguide portion 35 and the second waveguide portion 37 are connected by a conductive transition surface 39 of the hollow waveguide 15. Figures 3A to 3C In the example configuration of the microwave transmission device 13, the hollow waveguide 15 has a substantially rectangular cross-section (or more precisely, two different substantially rectangular cross-sections). However, it should be noted that the hollow waveguide 15 may have other cross-sections, such as a circular cross-section or an elliptical cross-section.

[0039] The microwave circuit board 34 includes a dielectric carrier 41 and a first conductor pattern 43 on the first side of the microwave circuit board 34 facing the hollow waveguide 15. For example... Figure 3A As schematically indicated, the first conductor pattern 43 includes a patch 45 and a first ground plane 47 that at least partially surrounds the patch 45. A microwave stripline 46 connects the patch 45 to the microwave circuit system 19. Figure 3A (Not shown in the image) Connection. For example... Figure 3A As schematically indicated, the first ground plane 47 substantially completely surrounds the patch 45 and the microwave stripline 46. A gap 48 exists in the first conductor pattern 43 separating the patch 45 and the first ground plane 47. The patch 45 is shown herein as substantially rectangular because it is adapted to the hollow waveguide 15. As those skilled in the art will understand, other patch configurations may be suitable for other waveguide configurations.

[0040] exist Figure 3A In the example configuration, the microwave circuit board 34 further has a second conductor pattern 49 on a second side of the dielectric carrier 41 opposite to the first side. The second conductor pattern 49 includes a second ground plane 51 arranged opposite to the patch 45 and the first ground plane 47. Figure 3A As schematically shown, the first ground plane 47 and the second ground plane 51 are interconnected by a conductive via 52 extending through the dielectric carrier 41.

[0041] like Figure 3A As schematically indicated, the first end 53 of the conductive hollow waveguide 15 is in conductive contact with the first ground plane 47 of the microwave circuit board 34. Furthermore, as... Figure 3A It can also be seen that the first ground plane 47 extends into the cross-sectional area of ​​the second waveguide portion to define at least one conductive pocket 55a to 55b together with the second waveguide portion 37 (the conductive sidewall of the second waveguide portion 37) of the hollow waveguide 15 and the transition surface 39.

[0042] Specifically, we will now refer to Figure 3B The schematic perspective view in the figure describes the hollow waveguide 15 of the microwave transmission device 13 in more detail.

[0043] Reference Figure 3B This schematically indicates the signal propagation path 57 defined by the hollow waveguide 15. As further mentioned above, the first waveguide portion 35 has a first waveguide cross-sectional area 59 in a cross-section having a plane perpendicular to the signal propagation path 57, and the second waveguide portion 37 has a second waveguide cross-sectional area 61 in a cross-section having a plane perpendicular to the signal propagation path 57.

[0044] The distance along the signal propagation path 57 from the first end 53 of the hollow waveguide 15 to the conductive transition surface 39 of the hollow waveguide 15, or the depth of the second waveguide portion 37, can advantageously be greater than 0.2 mm and less than 2 mm. A minimum depth is selected to ensure that the microwave transmission device 13 meets intrinsic safety requirements, and a maximum depth is selected for efficient transmission of microwave energy between the patch 45 and the first waveguide portion 35 of the hollow waveguide 15.

[0045] Furthermore, the transition surface 39 may advantageously extend a distance d1 in at least one direction perpendicular to the signal propagation path 57, the distance d1 corresponding to 0.4 to 0.6 times the center wavelength of the predefined wavelength range for which the microwave transmission device 13 is configured.

[0046] exist Figure 3BIn the example configuration, the first waveguide portion 35 has a rectangular cross-section having a first side 63 and a second side 65 perpendicular to the first side 63. The second waveguide portion 37 also has a rectangular cross-section having a first side 67 parallel to the first side 63 of the first waveguide portion 35 and a second side 69 parallel to the second side 65 of the first waveguide portion 35.

[0047] In this particular configuration, it has been found that the first side 67 of the second waveguide portion 37 can advantageously be longer than the first side 63 of the first waveguide portion 35 by a distance corresponding to at least 0.8 times the center wavelength of the predefined wavelength range, and the difference between the length of the second side 69 of the second waveguide portion 37 and the length of the second side 65 of the first waveguide portion 35 can be less than a distance corresponding to 0.4 times the center wavelength of the predefined wavelength range. For example, the transition surface 39 can advantageously extend a distance d2 in at least one direction perpendicular to the signal propagation path 57, which corresponds to a distance less than 0.2 times the center wavelength of the predefined wavelength range for which the microwave transmission device 13 is configured. This is done to prevent the formation of additional propagation modes in the microwave transmission device 13. According to an embodiment, the distance d2 can advantageously be close to zero, such that the length of the second side 69 of the second waveguide portion 37 is substantially equal to the length of the second side 65 of the first waveguide portion 35.

[0048] Figure 3C Indicatively Figure 3A The microwave transmission device 13 in the middle along Figure 3A The side view of the section cut by line A-A' in the diagram. Figure 3C The side view in the figure shows more clearly the first conductor pattern 43 and the second conductor pattern 49 of the microwave circuit board 34, as specifically and clearly indicating the first conductive pocket 55a and the second conductive pocket 55b defined by the first ground plane 47, the second waveguide portion 37 of the hollow waveguide 15 and the transition surface 39.

[0049] Those skilled in the art will recognize that the present invention is by no means limited to the preferred embodiments described above. Rather, many modifications and variations are possible within the scope of the appended claims.

Claims

1. A microwave transmission arrangement, comprising: a conductive hollow waveguide configured to guide microwave signals in a predefined wavelength range in a predefined propagation mode along a signal propagation path defined by the hollow waveguide, the hollow waveguide having a first waveguide portion having a first waveguide cross-sectional area, a second waveguide portion between a first end of the hollow waveguide and the first waveguide portion, the second waveguide portion having a second waveguide cross-sectional area larger than the first waveguide cross-sectional area, and a conductive transition surface of the hollow waveguide forming a transition between the first waveguide portion and the second waveguide portion; and a microwave circuit board comprising a dielectric carrier and a first conductor pattern on a first side of the dielectric carrier, the first conductor pattern comprising a patch for radiating or receiving microwave signals in a predefined wavelength range and a first ground plane surrounding the patch, wherein the first ground plane of the microwave circuit board is in conductive contact with the first end of the hollow waveguide and extends into the second waveguide portion cross-sectional area such that the first ground plane is present within an area of the first side of the microwave circuit board at the first end of the hollow waveguide confined by the hollow waveguide such that the first ground plane together with the conductive side walls of the second waveguide portion and the transition surface of the hollow waveguide define at least one conductive pocket. A minimum distance between the patch and the conductive transition surface of the hollow waveguide is at least 0.2 mm.

2. The microwave transmission device of claim 1, wherein, The second waveguide portion extends along the signal propagation path from the first end of the hollow waveguide by more than 0.2 mm and less than 2 mm.

3. The microwave transmission device of claim 2, wherein, The transition surface extends in a direction perpendicular to the signal propagation path by a distance corresponding to at least 0.4 times a center wavelength of the predefined wavelength range.

4. The microwave transmission device according to claim 1 or 2, wherein The transition surface extends in a direction perpendicular to the signal propagation path by a distance corresponding to less than 0.6 times a center wavelength of the predefined wavelength range.

5. The microwave transmission device according to claim 1 or 2, wherein 6. The microwave transmission arrangement according to claim 1 or 2, wherein: the first waveguide portion has a rectangular cross-section having a first side and a second side perpendicular to the first side; and the second waveguide portion has a rectangular cross-section having a first side parallel to the first side of the first waveguide portion and a second side parallel to the second side of the first waveguide portion.

7. The microwave transmission arrangement according to claim 6, wherein: the first side of the second waveguide portion is longer than the first side of the first waveguide portion by a distance corresponding to at least 0.8 times a center wavelength of the predefined wavelength range; and a difference between a length of the second side of the second waveguide portion and a length of the second side of the first waveguide portion is less than a distance corresponding to 0.4 times a center wavelength of the predefined wavelength range. the length of the second side of the second waveguide portion is equal to the length of the second side of the first waveguide portion.

8. The microwave transmission device of claim 7, wherein, ​ 9. The microwave transmission device according to claim 1 or 2, wherein The microwave circuit board has a second conductor pattern on a second side of the dielectric carrier opposite the first side, the second conductor pattern comprising a second ground plane arranged opposite the patch and the first ground plane, wherein the first and second ground planes are interconnected by a conductive via extending through the dielectric carrier.

10. The microwave transmission device of claim 1 or 2, wherein: The microwave transmission device further comprises microwave transceiver circuitry having an output for providing a microwave signal generated by the microwave transceiver circuitry and an input for receiving a microwave signal; and The patch is connected to at least one of the output and the input.

11. A communication and / or measurement system comprising: a microwave transmission device according to claim 10; and processing circuitry coupled to the microwave transceiver circuitry and configured to control the microwave transceiver circuitry to provide a microwave signal and / or to perform signal processing on a microwave signal received by the microwave transceiver circuitry.

12. A radar level gauge system for determining a fill level of a product in a tank, comprising: a microwave transmission device according to claim 10; an antenna coupled to the hollow waveguide of the microwave transmission device for radiating an electromagnetic transmit signal from the microwave transmission device towards a surface of the product and for returning an electromagnetic reflected signal resulting from a reflection of the electromagnetic transmit signal at the surface back to the microwave transmission device; and processing circuitry coupled to microwave transceiver circuitry comprised in the microwave transmission device and configured to determine a fill level based on a temporal relationship between the transmit signal and the reflected signal. ​

Images