waveguide

Abstract

The present invention relates to a waveguide (1) consisting of two waveguide parts (11, 12). Each waveguide part (11, 12) has a waveguide body (111, 121) and at least one waveguide channel (10) portion (110, 120), the portions (110, 120) being arranged so that, when the two waveguide parts (11, 12) are joined, they form at least one waveguide channel (10). The opposing surfaces (112, 122) of the two waveguide parts are formed parallel to each other. Recesses (2, 23-26) are formed in the sidewalls (114, 124) of the waveguide channel (10). The width (b) and height (h) of the recesses (2, 23-26) are substantially smaller than half the wavelength of the signal for which the at least one waveguide channel (10) is designed.

Description

[Technical Field]

[0001] The present invention relates to a waveguide consisting of two joined waveguide parts. Each waveguide part has at least one portion of a waveguide channel (i.e., a portion of one waveguide channel or portions of multiple waveguide channels), in particular the upper or lower half of at least one waveguide channel. The waveguide parts are joined by, for example, welding, gluing, screwing, etc. After the waveguide parts are joined, they form at least one waveguide channel. The facing surfaces of the two waveguide parts are formed parallel to each other.

[0002] The present invention further relates to a system comprising a waveguide and a further waveguide or a circuit board. The waveguide has a waveguide channel which is connected at its output to the further waveguide or the circuit board. The connection can be achieved, for example, by welding, gluing or screwing. The surfaces of the waveguide at the outlet of the waveguide channel and the surface of the further waveguide or the circuit board which are connected to each other are formed parallel to each other. [Background technology]

[0003] For example, a waveguide can be produced by forming two waveguide parts and then joining them together. Each waveguide part has a waveguide body, and at least one waveguide channel section is machined into the waveguide body by a method known per se, for example, milling or injection molding. The two waveguide parts are then joined together at their waveguide bodies to create a strong connection. During joining, the at least one waveguide channel section is aligned one above the other and combined into at least one waveguide channel. The joining can be performed by a method such as screwing, gluing, press-fitting, or welding.

[0004] At the joints, leakage of electromagnetic waves transmitted through the waveguide can occur. This is due to the interruption of the current path at the surface due to imperfect galvanic contact. From Montgomery et al., "Principles of Microwave Circuits," Stevenage: IET, 1987, it is known to divide a waveguide at a region where little, ideally no, current flows. In a rectangular waveguide, for example, this region is located in the middle of the longer side with respect to the fundamental mode. When the waveguide is divided at this region, symmetry is largely maintained, and no leakage occurs even if there is imperfect galvanic contact between the two waveguide parts, for example, due to bonding or press-fitting.

[0005] However, this does not completely prevent leakage. Even if the waveguide design were perfectly symmetrical (which is usually not the case due to components such as bends and transistors), small imperfections and manufacturing tolerances will result in a slightly asymmetric waveguide, which will result in at least a small amount of energy leaking between the waveguide parts. However, the smaller the asymmetry, the smaller the leakage, so when the asymmetry is small enough, the leakage can be neglected in some applications.

[0006] Typically, gaps remain between the waveguide bodies. The aligned surfaces of the waveguide bodies run parallel to each other and can be considered parallel plates of a parallel-plate capacitor. Even a small amount of leakage can cause excitation of a parallel-plate mode between the parallel surfaces of the waveguide bodies of a waveguide component. As long as the amount of energy is small enough, the leakage can be ignored. However, excitation can cause resonance within the gap between two waveguide bodies of a waveguide component or between adjacent waveguide channels. Resonance can significantly increase the amount of energy in the parallel-plate mode, resulting in a reduction in the mode propagating within the waveguide. This results in increased leakage and degraded performance of the waveguide (or a waveguide antenna using a waveguide). The occurrence of resonance depends on the frequency used, as well as the geometric boundary conditions of the waveguide and the gap between the waveguide components. This can prevent the use of waveguide-related designs or require welding for joining.

[0007] Electromagnetic leakage can also occur when a waveguide is connected to an additional waveguide or circuit board. Here, the waveguide does not necessarily have to consist of two waveguide components as described above. Typically, a gap remains between the waveguide bodies. The surfaces of the waveguide and the additional waveguide or circuit board extend parallel to each other at the connection point, which can be considered parallel plates of a parallel-plate capacitor. Even a small amount of leakage can cause excitation of a parallel-plate mode between the parallel surfaces. As long as the amount of energy is sufficiently small, the leakage can be ignored. However, excitation can cause resonance within the gap between the waveguide and the additional waveguide or circuit board. Resonance can significantly increase the amount of energy in the parallel-plate mode, resulting in a reduction in the mode propagating within the waveguide. This increases leakage and degrades the performance of the waveguide (or a waveguide antenna using a waveguide). The occurrence of resonance depends on the frequency used, as well as the geometric boundary conditions of the waveguide and the gap between the waveguide and the additional waveguide or circuit board. This may preclude the use of waveguide designs or may require welding at the joint. Summary of the Invention

[0008] The waveguide according to the present invention has a recess formed in the sidewall of the waveguide channel. The recess is preferably formed perpendicular to the sidewall, forming a cavity in the sidewall. The recess can have various shapes, such as rectangular, circular, or conical. The width and height of the recess in the sidewall are substantially smaller than half the wavelength of the signal in free space (<<λ0 / 2) for which at least one waveguide channel is designed. The wavelength of the signal in free space corresponds to the wavelength of the parallel-plate mode. For example, the width and height of the recess are each approximately one-quarter of the wavelength of the signal in free space (<λ0 / 2). The position and depth of the recess can essentially be freely selected as long as the condition that the width and height are substantially smaller than half the wavelength of the signal in free space is met. Due to the dimensions of the recess, the propagation mode in the waveguide channel is not affected by or interacts with the recess, and therefore the cutoff frequency associated with the recess is not reached, and the power of the propagation mode remains unchanged.

[0009] According to one embodiment, a recess is provided in a waveguide consisting of two joined waveguide components, where the recess is positioned at the junction, and a parallel plate mode is generated in the gap between the two waveguide bodies of the waveguide components caused by the imperfect joining.

[0010] According to a further aspect, a recess is provided in a system including a waveguide and a further waveguide or circuit board connected to the waveguide. The waveguide in this system can generally be any type of waveguide, i.e., the aforementioned waveguide consisting of two waveguide components, or a one-piece waveguide, and has at least one waveguide channel. The further waveguide or circuit board is connected to this waveguide at the outer surface of the waveguide where the output of the waveguide channel is located. The opening is called the output of the waveguide channel, and through the opening, a signal is decoupled from or coupled to the waveguide. Therefore, the input of the waveguide channel is also considered an output here. Explicitly, openings in portions of the waveguide channel that are closed when joined to form the waveguide channel cannot be considered an outlet. A parallel plate mode occurs in the gap at the connection between the waveguide body of the waveguide and the waveguide body of the further waveguide or circuit board.

[0011] The recesses can also be considered as stubs. As a result, the propagation characteristics of the parallel plate mode at the surface of the waveguide body are changed, thereby shifting the resonant frequency or attenuating the resonance. By controlling the positioning and number of recesses, the resonant frequency of the waveguide body can be controlled and eliminated within the relevant frequency band. As a result, energy leakage from the waveguide is reduced.

[0012] Preferably, the recess is provided on the surface of the waveguide body where the joining or connection is realized to generate the parallel plate mode. When joining waveguide components, the relevant surface of the waveguide body faces the other waveguide component and is the surface on which at least one waveguide channel portion is machined. When connecting to a further waveguide or a circuit board, the relevant surface is the surface that has the exit of the waveguide channel. There, the propagation characteristics of the parallel plate mode can be effectively changed. Furthermore, the surface is easily accessible for external processing.

[0013] When the waveguide is composed of two waveguide parts, recesses are preferably formed in the surfaces of the two waveguide parts. The positions and shapes of the recesses match. When the waveguide parts are joined, the recesses of the two waveguide parts mate with each other, forming a common recess in at least one waveguide channel. This makes it easy to form the recesses during the manufacturing of the waveguide parts. Furthermore, in this case, the recesses are arranged symmetrically within the waveguide channel.

[0014] A plurality of recesses can be formed in the sidewall, the recesses being arranged adjacent to each other and preferably at the same height, which allows for selective and particularly effective suppression of the parallel plate mode.

[0015] The recesses are particularly advantageous in the waveguide channel configuration described below, but may be applied in any configuration. In one embodiment, a waveguide consisting of two waveguide components has a bent or meandered waveguide channel surrounding a region where a resonant cavity can occur within the gap between the two waveguide components. Resonance occurs when one dimension of the resonant cavity corresponds to approximately half (or a multiple of) the free-space wavelength of the signal propagating through the waveguide channel (l ≈ λ0 / 2). A recess is preferably located in this region of the waveguide body of the first waveguide component, surrounded by the bent or meandered waveguide channel. This destroys the resonant cavity and significantly reduces parallel-plate modes within the gap between the waveguide bodies. Generally, any shape of waveguide surrounding such a region where a resonant cavity can occur is relevant here. In particular, a U-shaped waveguide channel, in which the waveguide channels run parallel in two legs, a V-shaped waveguide channel, or an L-shaped waveguide channel, in which the legs are angled relative to each other, are relevant.

[0016] In a further embodiment, a waveguide consisting of two waveguide components has two parallel waveguide channels. In the region of the waveguide body between the two parallel waveguide channels, a resonant cavity may form in the gap between the two waveguide components. Furthermore, unwanted energy coupling may occur between the two waveguide channels. Resonance occurs when the distance between the two parallel waveguide channels corresponds to approximately half (or a multiple of) the free-space wavelength of the signal propagating through the waveguide channels (l ≈ λ0 / 2). This design is particularly advantageous in that it includes multiple recesses positioned adjacent to each other. This destroys the resonant cavity and significantly reduces parallel-plate modes in the gap between the waveguide bodies. Furthermore, this prevents energy coupling between the waveguide channels through the gap.

[0017] The recess is particularly advantageous when the waveguide has a choke at the connection to the further waveguide or circuit board. The choke is used to reduce leakage, especially when the connection is not realized by welding. However, such a choke only works optimally with perfect symmetry. Any misalignment between the waveguide and the further waveguide or circuit board breaks the symmetry and creates a resonance on the surface of the waveguide body between the waveguide channel and the choke. Preferably, a recess is formed in the sidewall of the waveguide channel facing the choke. Preferably, the recess penetrates the sidewall and connects the choke to the waveguide channel. This breaks the resonance between the waveguide channel and the choke.

[0018] Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view of a waveguide joined from two waveguide sections comprising a waveguide channel. [Figure 2] 1 is a cross-sectional view of a recess in a waveguide according to one embodiment of the present invention. [Figure 3]1 is a top perspective view of a waveguide part of an exemplary embodiment of a waveguide according to the present invention, comprising a waveguide channel of a first configuration; [Figure 4] 10 is a top perspective view of a waveguide part of an exemplary embodiment of a waveguide according to the present invention, comprising a second configuration of waveguide channels; FIG. [Figure 5] 10 is a front perspective view of a further exemplary embodiment of a waveguide according to the present invention having a choke at the outlet of the waveguide channel; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] 1 shows a waveguide 1 made up of two waveguide components 11, 12. The first waveguide component 11 has a waveguide body 111 in which a cutout 110 is formed, which in this example has a rectangular cross section and extends in a third direction through the waveguide body 111. Similarly, the second waveguide component 12 has a waveguide body 121 in which a cutout 120 is formed, which in this example has the same shape as the cutout 110 of the first waveguide component 11. The waveguide bodies 111, 121 have opposing surfaces 112 and 122 outside the cutout, which surfaces 112 and 122 extend parallel to each other. To assemble the waveguide 1, the two waveguide parts 11, 12 are joined at their surfaces 112, 122. In addition to welding, adhesive bonding or screwing can also be used as joining methods. By joining, the two recesses 110, 120 come together to form the waveguide channel 10, which is formed as a rectangular hollow tube, through which an electromagnetic signal (not shown) can be transmitted. That is, the recesses 110, 120 are part of the waveguide channel 10, and can be easily formed separately in the waveguide bodies 111, 121, for example by milling or injection molding, to form the waveguide channel 10 when joined. By appropriately forming the recesses 110, 120, waveguide channels of different shapes and also multiple waveguide channels can be formed within the same waveguide 1. For this, see FIGS. 3 and 4. Upon joining, a gap 13 may occur between surfaces 112 and 122, which gap 13 is shown larger than actual scale in the drawings. Because the two surfaces 112 and 122 are parallel to each other, a parallel plate mode may form within gap 13. This results in leakage of electromagnetic energy (indicated by arrow 131) of the signal being transmitted in waveguide channel 10, thereby reducing the energy of the signal within waveguide channel 10.

[0021] In the further figures, identical components are characterized by identical reference symbols, for the description of which reference is made to the above description. Figure 2 shows a cross section of a waveguide 1 according to the invention, constructed as shown in Figure 1. The waveguide 1 according to the invention has a recess 2 extending vertically from the waveguide channel 10 into the waveguide body 111, 121 and formed symmetrically with respect to the gap 13. The first waveguide part 11 has a rectangular recess 21 on its surface 112 in the side wall 114 of the cutout 110 that forms part of the waveguide channel 10. The second waveguide part 12 has a rectangular recess 22 on its surface 122 in the side wall 124 of the cutout 120 that forms the other part of the waveguide channel 10, the recess 22 corresponding to and located at the same position as the recess 21 of the first waveguide part 12. The joining of the waveguide parts 11, 12 brings the two recesses 21, 22 together to form a common recess 2, which here has a rectangular parallelepiped shape. In other embodiments (not shown here), the recess 2 may have another shape, for example a cylindrical shape. The recess 2 has a height h, which is significantly smaller than the wavelength of the signal in free space (h<<λ), here for example a quarter of the wavelength of the signal in free space (h=λ / 4). Furthermore, the recess has a width d (not shown in FIG. 2 because it extends perpendicular to the plane of the paper; see FIGS. 3 and 4), which is likewise substantially smaller than the wavelength of the signal in free space (d<<λ), here for example a quarter of the wavelength of the signal in free space (b=λ / 4).

[0022] 3 and 4 show exemplary embodiments of a waveguide 1 according to the present invention, each having a different configuration of the waveguide channel 10. Each of Figures 3 and 4 shows a perspective view from above of a first waveguide part 11. A second waveguide part 12, not shown for clarity, is constructed similarly to the first waveguide part 11.

[0023] 3, the waveguide channel 10 is formed in a U-shape, with a base portion 101 and two leg portions 102, 103 extending parallel to one another. The base portion 101 and the leg portions 102, 103 surround a region of the waveguide body 111 on three sides. If the length l of this region of the waveguide body 111 between the leg portions 102, 103, i.e., the distance between the leg portions 102, 103, is close to half the wavelength of the signal in free space (l≈λ / 2), a resonant cavity may form in the enclosed region at the gap 13 between the parallel waveguide bodies 111 and 121, and this resonant cavity amplifies the leakage of electromagnetic energy. In other exemplary embodiments (not shown), the waveguide channel may be formed in a V- or L-shape and may similarly surround a region within which a resonant cavity may form. According to the present invention, a plurality of recesses (four in this example) 23-26 are provided in the sidewall 114 of one leg 102 of the waveguide channel 10 in the direction of the enclosed area. As shown with reference to FIG. 2, these recesses 23-26 form a common recess together with a recess (not shown) in the second waveguide part 12. The recesses 23-26 each have the same width b and the same height h, which are each substantially smaller than half the wavelength of a signal in free space, for example, one-quarter of the wavelength of the signal, and are spaced apart at the same distance d, which corresponds to, for example, approximately half the wavelength of the signal (d≈λ₀ / 2). The recesses 23-26 change the geometric boundary conditions, so that the parallel-plate mode is suppressed and no or only little leakage occurs.

[0024] FIG. 4 shows two waveguide channels 10 and 100 extending parallel to each other. The waveguide channels surround a region of a waveguide body 111 from two opposing sides. If the length l of this region of the waveguide body 111 between the waveguide channels 10 and 100, i.e., the distance between the waveguide channels 10 and 100, is close to half the wavelength of the signal in one of the waveguide channels 10 and 100 (l≈λ0 / 2), a resonant cavity may occur in the surrounded region in the gap 13 between the parallel waveguide bodies 111 and 121, which amplifies the leakage of electromagnetic energy. According to the present invention, a plurality of (here, four) recesses 23-26 are provided in the sidewall 114 of one leg 102 of the waveguide channel 10, facing the other waveguide channel 100 and the surrounded region. 2, these recesses 23-26 form a common recess together with a recess of the second waveguide part 12 (not shown). The recesses 23-26 each have the same width b and the same height h, which are each substantially smaller than half the wavelength of the signal in free space, here for example one-quarter of the wavelength of the signal, and are spaced apart at the same distance d, which here for example corresponds to approximately half the wavelength of the signal (d≈λ0 / 2). The recesses 23-26 change the geometric boundary conditions, so that the parallel-plate modes are suppressed and no or only little leakage occurs.

[0025] FIG. 5 shows a front view of the waveguide 3. The waveguide 3 may be the aforementioned waveguide 1, which is made up of two waveguide components. In general, the waveguide 3 may also be constructed in another form, for example in one piece. The waveguide 3 has a waveguide body 31 and a waveguide channel 30 configured as a rectangular hollow tube within the waveguide body 31. The outlet of the waveguide channel 30 is located on a surface 32 of the waveguide body 31 facing the front. The waveguide 3 is connected via this surface 32 to a further waveguide (not shown) or a circuit board (not shown), so that signals are coupled to or decoupled from a coupling point of the further waveguide or the circuit board via the output of the waveguide channel 30. At the outlet of the waveguide channel 30, a choke 4 is provided, surrounding the waveguide channel 30. According to the invention, the side wall 34 of the waveguide channel 30 at the surface 32 is provided with two recesses 27 and 28, which are arranged opposite each other and parallel to each other. In this example, recesses 27, 28 are formed on each long side of rectangular waveguide channel 30. In other embodiments (not shown), a different number and arrangement of recesses may be provided, e.g., two recesses on each long side and two recesses on each short side. Here, recesses 27, 28 penetrate sidewall 34, thus connecting waveguide channel 30 and choke 4. This breaks resonances that form between waveguide channel 30 and choke 4 in the gap between surface 32 of waveguide body 32 of waveguide 3 and another waveguide or circuit board, resulting in little or no leakage.

Claims

1. A waveguide (1) consisting of two waveguide parts (11, 12), each of which has a waveguide body (111, 121) and a portion (110, 120) of at least one waveguide channel (10), said portions (110, 120) being arranged to form said at least one waveguide channel (10) when said two waveguide parts (11, 12) are joined, and opposing surfaces (112, 122) of said two waveguide parts are formed parallel to one another. A recess (2, 23-26) is formed in the sidewall (114, 124) of the waveguide channel (10), the width (b) and height (h) of said recess (2, 23-26) being substantially smaller than half the wavelength of the signal for which said at least one waveguide channel (10) is designed. A waveguide (1) characterized in that

2. 2. A waveguide (1) according to claim 1, characterized in that the recesses (2, 23-26) are formed in the side walls (114, 124) perpendicular to the side walls (114, 124).

3. Waveguide (1) according to claim 1 or 2, characterized in that the recesses (2, 23-26) are formed in the surface (112, 122) of the waveguide body (111, 121).

4. 4. The waveguide (1) according to claim 3, characterized in that in each of the waveguide parts (11, 12), recesses (21, 22) are formed in the respective surfaces (112, 122), the positions of the recesses (21, 22) correspond to each other, and in the joined state of the waveguide (1), the recesses (21, 22) mate with each other to form a common recess (2).

5. 5. A waveguide (1) according to any one of claims 1 to 4, characterized in that the waveguide parts (11, 12) have a plurality of recesses (23-26) arranged adjacent to one another.

6. 6. The waveguide (1) according to any one of claims 1 to 5, characterized in that in the waveguide (1) having a bent or meandered waveguide channel (101, 102, 103) surrounding a region, the recesses (2, 23-26) are configured in a region of the waveguide body (111, 121) surrounded by the bent or meandered waveguide channel (101, 102, 103).

7. 7. The waveguide (1) according to claim 1, characterized in that in the waveguide (1) having two waveguide channels (10, 100) extending parallel to each other, the recesses (2, 23-26) are formed in the side wall (114) of one of the waveguide channels (10) toward the other waveguide channel (100).

8. 1. A system comprising a waveguide (3) having at least one waveguide channel (30) and a further waveguide or a circuit board, wherein the at least one waveguide channel (30) is connected at an output to the further waveguide or the circuit board, characterized in that recesses (27, 28) are formed in the side walls (34) of the at least one waveguide channel (30), the width (b) and height (h) of the recesses (27, 28) being smaller than half the wavelength of a signal for which the at least one waveguide channel (30) is designed.

9. 9. The system according to claim 8, wherein the recesses (27, 28) are formed in the side walls (34) perpendicular to the side walls (34).

10. 10. A system according to claim 8 or 9, characterized in that the recesses (27, 28) are formed in the surface (32) of the waveguide body (31).

11. 11. A system according to any one of claims 8 to 10, characterized in that the waveguide (1) has a number of recesses (27, 28).

12. 12. The system according to claim 8, wherein the waveguide (1) comprises a choke (4), and the recesses (27, 28) are formed in the side walls (34) of the waveguide channel (30) towards the choke (4).

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