WAVE CONDUCTOR ARRANGEMENT AND ANTENNA

Description

Field of invention

[0001] The invention relates to a waveguide arrangement for guiding electromagnetic waves and an antenna for a 3D radar device for detecting bulk material topologies comprising such a waveguide arrangement. Background of the invention

[0002] Electromagnetic waves in the GHz range are typically coupled from the circuit board into a rectangular waveguide via coaxial connectors or directly via a coupling pin. The connection between the IC and the waveguide is established using a stripline on a quartz substrate. This stripline has a waveguide excitation patch on one side and is bonded to the IC on the other. Alternatively, the waveguide excitation patch can be integrated directly onto the IC, eliminating the need for a bond wire. The open waveguide end of a radar or communications module manufactured using this technology can be used with a horn antenna. However, a rotationally symmetrical antenna is fed by a circular waveguide, necessitating a transition from the rectangular to the circular waveguide. This transition introduces insertion and attenuation losses.

[0003] The transition from an unfilled rectangular waveguide to a circular waveguide filled with dielectric material and positioned at a 90° angle requires a suitable coupling.

[0004] Documents EP 1 014 470 A2 and JP 2004 120792 A each describe an arrangement with a dielectric surrounded by conductive plates and projecting into a circular waveguide. Document US 2002 / 030632 A1 describes a three-dimensional dielectric multi-aperture antenna with an extremely wide bandwidth, combining the properties of conical dielectric rod antennas and coaxial waveguide transmission lines. Document US 2 961 658 A describes a steerable leakage wave antenna designed as a series-fed array antenna consisting of dielectric rod radiators, fed in series by a rectangular waveguide, with reflective phase shifters arranged between the rod radiators. These phase shifters are designed as short-circuited circular waveguides filled with a dielectric ferrite material. The publication Delos B. Churchill: "Waveguide Windows for High-Power Microwave Tubes", IEEE International Convention Record, Vol. 11, 25.March 1963, pages 154-161 describes a convexly shaped dielectric window that projects from an end-face circular waveguide opening into a rectangular waveguide. Summary of the invention

[0005] The object of the invention is to create an effective transition from a rectangular waveguide to a circular waveguide.

[0006] The problem is solved by the subject matter of the independent patent claims. Advantageous embodiments are the subject matter of the dependent claims, the following description, and the figures.

[0007] According to a first aspect, a waveguide arrangement for guiding electromagnetic waves is provided, comprising a rectangular waveguide and a circular waveguide. The rectangular waveguide transitions into the circular waveguide at an angle, e.g., a 90° angle. The circular waveguide is filled with a dielectric material that projects into the rectangular waveguide at a transition section. The dielectric filling is beveled at a defined angle in the transition section, forming a transition surface that is inclined at the defined angle relative to the area of ​​the circular waveguide opening and divides the angle of the transition from the rectangular waveguide to the circular waveguide, e.g., a 90° angle.

[0008] The electromagnetic, high-frequency wave is thus guided from the injection point through the rectangular waveguide to the circular waveguide. Before entering the circular waveguide, it encounters a beveled transition surface of the dielectric material filling the circular waveguide, which extends into the rectangular waveguide at this bevel. This bevel reduces reflections, resulting in a low-loss transition with low reflection and attenuation. This, in turn, avoids or at least reduces so-called pseudo-echoes in the radar signal, which occur at the surface of the transition and can distort the measurement.

[0009] The use of a dielectric makes the arrangement more space-saving, as this allows the width of the overall arrangement to be smaller than half the wavelength of the maximum operating frequency range, as would be the case without a dielectric filling material, i.e., relative to air.

[0010] According to another embodiment, the angle of the bevel is preferably between 20° and 40°. Advantageous values ​​with respect to insertion loss and impedance matching are obtained in this range. For example, a very good result was achieved with a bevel angle of 36°. In this case, the beveled end of the dielectric extends 40.4% into the rectangular waveguide. If the circular waveguide is positioned at an angle other than 90° to the rectangular waveguide, other bevel angles may be optimal.

[0011] According to one embodiment, the dielectric filling at the transition section opposite the rectangular waveguide end of the circular waveguide has a lens. The lens protrudes at least partially from the circular waveguide on the side of the dielectric filling facing free space and allows the electromagnetic wave to exit the waveguide and be radiated with minimal reflection.

[0012] According to another embodiment, the lens has a small shoulder or projection around its circumference at the end opposite the rectangular waveguide at the transition section, i.e., on the side facing the circular waveguide, with which it rests on or against the end of the circular waveguide. This defines a precise penetration depth into the rectangular waveguide.

[0013] According to a further embodiment, the dielectric has an extension along the end face of the rectangular waveguide to define the exact penetration depth. The end face of the rectangular waveguide is the extended side of the circular waveguide extending into the rectangular waveguide, so that, for example, in the assembled state, the dielectric rests against or abuts the side opposite the circular waveguide opening at the transition. Since the dielectric, e.g., the polyetheretherketone material, is only extended along the end face and not across its entire width or circumference, a sufficiently large, free, chamfered transition area remains. This area can receive the waveguide wave and guide it into the circular waveguide without significantly reducing the insertion loss. This embodiment can be used, for example, if the dielectric does not have a lens or if the lens does not have a circumferential step.Furthermore, both variants are possible simultaneously.

[0014] According to another embodiment, the circular waveguide is positioned on the narrow side of the rectangular waveguide. The rectangular waveguide is thus contacted by the circular waveguide in the H-plane of electromagnetic wave propagation, so that the signal is coupled into the circular waveguide via the H-plane, i.e., via the narrow or flat side of the rectangular waveguide. If the waveguide arrangement is used for an antenna array with multiple waveguide assemblies, the width of the narrow side of the rectangular waveguide is decisive for the width of the individual waveguide assemblies, as explained and illustrated again below with reference to the drawings. This embodiment represents a further measure to make the waveguide arrangement, and thus also the antenna array, more compact.While it is technically possible to connect the rectangular waveguide in the E-plane of electromagnetic wave propagation via the circular waveguide, coupling the signal through the wide side of the rectangular waveguide increases the overall width of the assembly. According to another embodiment, the relative permittivity of the dielectric filling lies between 2 and 15. These values ​​have proven particularly advantageous with respect to wave propagation and the wavelength of the operating spectrum relative to the dimensions of the waveguides. Furthermore, the dielectric filling can exhibit an inhomogeneous permittivity.

[0015] According to another embodiment, the dielectric filling consists of the material polyetheretherketone (PEEK), which, due to its melting temperature of about 335°C, can also be used at high temperatures up to about 250°C, and which allows the electromagnetic waves to be conducted with low loss.

[0016] According to another embodiment, the dielectric filling consists of polytetrafluoroethylene (PTFE), which also has a high melting point and even lower losses in the conduction of electromagnetic waves. Due to its high thermal expansion at high temperatures, the most suitable plastic must be considered depending on the application. A combination of PEEK and PTFE can also be used.

[0017] According to another embodiment, the width of the overall arrangement is less than half the wavelength of the maximum operating frequency range of the arrangement. As explained above, this is made possible by the dielectric and the contacting in the H-plane, i.e., the narrow side of the rectangular waveguide.

[0018] A second aspect involves providing an antenna for a 3D radar system for detecting bulk material topologies. This antenna features a waveguide array as described above. Specifically, the antenna can be a column and row array antenna, where each array element corresponds to a waveguide array. In the mechanical design, the width of the waveguide array is a parameter determining the array size. Because the waveguide array is narrow due to H-plane coupling and the dielectric material, the array elements, i.e., the waveguide arrays, can be placed closer together.

[0019] Another aspect concerns the use of a waveguide arrangement described above and below in a radar measuring device, in particular in a 3D radar device, or a level radar measuring device. Brief description of the characters

[0020] In the following, exemplary embodiments of the invention are described in detail with reference to the accompanying figures. Neither the description nor the figures are to be interpreted as limiting the invention. Here, [the following is shown] Fig. 1 a waveguide arrangement with a rectangular waveguide and a circular waveguide according to an embodiment, Fig. 2 a diagram of the waveguide arrangement adaptation, Fig. 3 a diagram of the insertion loss of the waveguide arrangement, Fig. 4 a top view of the waveguide arrangement according to an exemplary embodiment, Fig. 5 an exemplary setup of several of the waveguide arrangements according to an embodiment, Fig. 6 a waveguide arrangement with a rectangular waveguide and a circular waveguide according to an exemplary embodiment.

[0021] The drawings are merely schematic and not to scale.

[0022] Generally, identical or similar parts are marked with the same reference symbols. Detailed description of the figures

[0023] Fig. 1 Figure 1 shows a waveguide arrangement 100 comprising a rectangular waveguide 102 and a circular waveguide 104 according to an exemplary embodiment. The rectangular waveguide 102 is positioned at one end on one of its narrow sides 114 at a right angle to the circular waveguide 104. The transition 110 is flush. The circular waveguide 104 has a dielectric filling 116 and transitions flush into the rectangular waveguide 102 at the edge 110, with a portion of the dielectric filling 116 projecting into the rectangular waveguide 102. The angle formed between the surface of the opening 122 and the transition surface 126 of the chamfer of the dielectric 116 is advantageously e.g. 36°, so that the dielectric 116 projects approximately 40% into the rectangular waveguide 102 in relation to the wide side 112 of the rectangular waveguide 102.

[0024] At the outlet of the circular waveguide 104, a lens 106 ensures a transition from the filled waveguide 104 to free space with minimal reflection. The lens 106 has a rim 108 that rests against the end of the circular waveguide 104, thus defining a precise penetration depth of the dielectric filling 116 into the rectangular waveguide 102.

[0025] Fig. 2 Figure 1 shows a diagram of the transition from the rectangular waveguide 102 to the circular waveguide 104, that is, how much energy of the electromagnetic wave is reflected back by the described arrangement 100 consisting of the rectangular waveguide 102 and the circular waveguide 104. As shown in Figure 100. Fig. 2 To be detected, this is less than -15 dB in the range between 73 GHz and 85 GHz, with a minimum of -27 dB at 76 GHz.

[0026] Fig. 3 The diagram shows the insertion loss of the arrangement 100, which is approximately 3 dB at 71.5 GHz and only approximately 1 dB from 74 GHz onwards.

[0027] From the Figuren 2 und 3 The advantage of the presented waveguide arrangement with regard to its electrical properties thus becomes clear. The advantage with regard to the form factor is shown in the following two drawings.

[0028] Fig. 4 Figure 1 shows a top view of the arrangement 100 according to an exemplary embodiment, from which the width 402 of the overall arrangement of the rectangular waveguide 102 and the circular waveguide 104 is evident. It can be seen that the width 408 of the circular waveguide 104 is approximately the same as the narrow side 404 of the rectangular waveguide 102, which allows several such waveguide arrangements 100 to be placed close together, as shown in Figure 1. Fig. 5 This is made clear.

[0029] Fig. 5 Figure 502 shows an exemplary basic structure of an antenna 500 or an antenna array 500 on a circuit board 502, in which several of the waveguide arrangements 100 are located next to each other, and in which the advantage of the waveguide arrangement with regard to the dimensions in the width of an array 500 can be seen.

[0030] For example, the connection of an IC or circuit, e.g., in a housing 504, is made to one of the waveguides 100. The rectangular waveguide 102 receives the wave, which then passes through it into the circular waveguide 104 and is radiated from it.

[0031] While in Fig. 5 For the sake of clarity, only three one-dimensionally arranged elements are shown; a real array can have far more arrangements (100) or elements (100) in two dimensions, where the elements can, for example, be offset, have different lengths, and be packed more densely than in the example. Fig. 5 shown.

[0032] Fig. 6 Figure 1 shows a waveguide arrangement 100 with a rectangular waveguide 102 and a circular waveguide 104 according to a further embodiment. In this example, the penetration depth of the dielectric 116 is determined not by the protruding edge 108 of a lens 106 (see Figure 1). Fig. 1 ) now by an extension 602 of the dielectric 116 along the end face 120 of the rectangular waveguide 102, such that in the assembled state the dielectric 116 rests on, or abuts, the side 124 of the rectangular waveguide 102 that is opposite the opening 122 to the circular waveguide 104. Despite the extension 602, the chamfered transition surface 126 remains sufficiently large to accommodate the waveguide wave from the rectangular waveguide 102 without significant additional insertion loss.

[0033] The waveguide arrangement 100, 600 thus achieves an effective transition from a rectangular waveguide 102 to a circular waveguide 104, which are positioned at an angle to each other. In this context, "effective" means, in particular, that a transition between the two waveguide types is created that is as broadband and attenuated as possible for high-frequency signals, and that a space-saving arrangement for feeding an antenna array 500 is provided.

[0034] This is achieved by a clever design of the end of the dielectric filling 116 that projects into the rectangular waveguide 102. This filling protrudes into the rectangular waveguide 102 to an advantageously chosen extent and is chamfered at an advantageously chosen angle.

[0035] For the expert, it is self-evident that other variations are also possible. For example, the rectangular waveguide 102 can be contacted in the E-plane by the circular waveguide 104. While this also achieves low insertion loss and good matching due to the beveled shape of the dielectric filling, in this case the contact would have to take place on the wide side 112 of the rectangular waveguide 104, which significantly increases the overall width 402 of the arrangement and thus prevents the realization of space-saving arrays.

[0036] Furthermore, the dielectric filling 116 can also be realized without lens 106, which on the one hand allows for simpler and more cost-effective production, but on the other hand the positive effect regarding the radiation properties of the electromagnetic wave compared to an arrangement with lens 106 is not used.

[0037] Furthermore, the angle between the rectangular waveguide and the circular waveguide can differ from 90°.

Claims

1. A waveguide arrangement (100, 600) for guiding electromagnetic waves, comprising a rectangular waveguide (102) and a circular waveguide (104); wherein the rectangular waveguide (102) has a lateral opening (122) in a narrow or wide side of the rectangular waveguide (102) and transitions at right angles into the circular waveguide (104); the circular waveguide (104) is filled with a dielectric material (116); characterised in that the dielectric material (116) is bevelled at a defined angle in a transition section so that a bevel with a transition surface (126) that is inclined by the defined angle relative to the surface of the opening (122), and the dielectric material with the bevel and with a defined penetration depth protrudes into the rectangular waveguide (102) along an end face of the rectangular waveguide.

2. The waveguide arrangement (100, 600) according to claim 1, wherein the angle of the bevel is between 20° and 40°.

3. The waveguide arrangement (100, 600) according to claim 1 or 2, wherein the dielectric material (116) has a lens (106) at the transition section with the end of the rectangular waveguide (102) opposite the end of the circular waveguide (104).

4. The waveguide arrangement (100, 600) according to claim 3, wherein the lens (106) at the transition section with the end of the circular waveguide (104) opposite the rectangular waveguide (102) has a circumferential projection on which the dielectric material stands up on the end of the circular waveguide (104) and with which the lens (106) is supported on the end of the circular waveguide (104).

5. The waveguide arrangement (100, 600) according to any of the preceding claims, wherein the dielectric material (116) extends along an end face (120) of the rectangular waveguide (102) so that the dielectric material (116) stands up on the side (124) opposite the opening (122) at the transition.

6. The waveguide arrangement (100, 600) according to any of the preceding claims, wherein the transition is characterised in that the circular waveguide (104) stands on the narrow side (114) of the rectangular waveguide (102).

7. The waveguide arrangement (100, 600) according to any of the preceding claims, wherein the relative permittivity of the dielectric material (116) is between 2 and 15.

8. The waveguide arrangement (100, 600) according to any of the preceding claims, wherein the dielectric material (116) consists of polyether ether ketone, PEEK.

9. The waveguide arrangement (100, 600) according to any one of claims 1 to 7, wherein the dielectric material (116) consists of the material polytetrafluoroethylene, PTFE.

10. The waveguide arrangement (100) according to any of the preceding claims, wherein the rectangular waveguide has a narrow side and a wide side, the width (408) of the circular waveguide (104) corresponds approximately to the narrow side of the rectangular waveguide, and wherein the total width (402) of the waveguide arrangement (100) is less than half the wavelength of the maximum operating frequency range of the waveguide arrangement (100).

11. An antenna (500) for a 3D radar device for detecting bulk material topologies, comprising a waveguide arrangement (100) according to any one of claims 1 to 10.

12. Use of a waveguide arrangement (100) according to one of claims 1 to 10 in a radar measuring device.