Waveguide

Abstract

The invention relates to a waveguide (1) consisting of two waveguide parts (11, 12). Each waveguide part (11, 12) has a wave guide body (111, 121) and a part (110, 120) of at least one waveguide channel (10) which are arranged such that they form the at least one waveguide channel (10) when the two waveguide parts (11, 12) are joined together. The opposing surfaces (112, 122) of the two waveguide parts are parallel. A recess (2, 23 - 26) is provided in a side wall (114, 124) of a waveguide channel (10). The width (b) and the height (h) of the recess (2, 23 - 26) are substantially smaller than half the wavelength of a signal for which the at least one waveguide channel (10) is designed.

Description

[0001] Description

[0002] title

[0003] Waveguide

[0004] The present invention relates to a waveguide consisting of two waveguide parts that are joined together. Each waveguide part comprises a part of at least one waveguide channel (i.e., a part of a waveguide channel or a part of several waveguide channels), in particular an upper or lower half of the at least one waveguide channel. The waveguide parts are, for example, welded, glued, screwed, or similarly connected. After the waveguide parts are joined together, they form the at least one waveguide channel. Opposing surfaces of the two waveguide parts are parallel.

[0005] The invention also relates to a system comprising a waveguide and a further waveguide or a circuit board. The waveguide has a waveguide channel, which is connected to the further waveguide or the circuit board at its output. The connection is realized, for example, by welding, gluing, or screwing. The surface of the waveguide at the output of the waveguide channel and the surface of the further waveguide or the surface of the circuit board being connected are parallel.

[0006] State of the art

[0007] Waveguides are manufactured, for example, by forming two waveguide parts and then joining them together. Each waveguide part has a waveguide body into which a part of at least one waveguide channel is machined using conventional methods, such as milling or injection molding. The two waveguide parts are then joined together at their waveguide bodies, thus creating a firm connection. During joining, the parts of the at least one waveguide channel are aligned one above the other and combined to form at least one waveguide channel. Joining is achieved, for example, by screwing, gluing, press-fitting, welding, or similar methods.

[0008] Leakage of electromagnetic waves carried within the waveguide can occur at the joint. This results from the interruption of current paths at the surface due to imperfect galvanic contacts. From the publication Montgomery et al.: Principles of Microwave Circuits. Stevenage: I ET, 1987, it is known that the waveguide can be split in a region where only small, or ideally no, currents flow. For example, in a rectangular waveguide, this region for the fundamental mode is in the middle of the longer side. If the waveguide is split in this region, the symmetry is largely maintained and no leakage occurs, even if there is imperfect galvanic contact between the two waveguide sections, for example, due to gluing or a press fit.

[0009] However, even this approach cannot completely eliminate leakage. Even if the waveguide design were perfectly symmetrical, which is usually not the case due to bends and components such as transistors, small defects and manufacturing tolerances will result in a slightly asymmetric waveguide, resulting in at least a small amount of energy leaking between the waveguide sections. However, small asymmetries also lead to smaller leakages, so that if the asymmetry is small enough, depending on the application, the leakage is negligible.

[0010] A gap typically remains between the waveguide bodies. The aligned surfaces of the waveguide bodies run parallel to each other, so they can be thought of as the plates of a parallel plate capacitor. Even the smallest leakage can generate excitation of a parallel plate mode between the parallel surfaces of the waveguide bodies of the waveguide sections. As long as the amount of energy is small enough, the leakage can be neglected. However, the excitation can cause resonance within the gap between the two waveguide bodies of the waveguide sections or between adjacent waveguide channels. Resonance can drastically increase the energy amount of the parallel plate mode, which leads to a reduction in the mode propagating in the waveguide. As a result, the leakage increases and the performance of the waveguide (or of a waveguide antenna using the waveguide) is reduced.The occurrence of resonances depends on the frequency used, the geometric boundary conditions of the waveguide, and the gap between the waveguide sections. This can make waveguide designs unusable or require welding during assembly.

[0011] Leakage of electromagnetic waves can also occur when a waveguide is connected to another waveguide or to a circuit board. In this case, the waveguide does not have to consist of two waveguide sections as described above. Typically, a gap remains between the waveguide bodies. The surface of the waveguide and the surface of the other waveguide or the surface of the circuit board run parallel to each other at the connection point, so they can be regarded as the plates of a parallel plate capacitor. Even the smallest leakage can generate an excitation of a parallel plate mode between the parallel surfaces. As long as the amount of energy is small enough, the leakage can be neglected. However, the excitation can lead to resonance within the gap between the waveguide and the other waveguide or the circuit board.Resonance can drastically increase the energy of the parallel-plate mode, leading to a reduction in the propagating mode in the waveguide. As a result, leakage increases and the performance of the waveguide (or a waveguide antenna using the waveguide) decreases. The occurrence of resonances depends on the frequency used, the geometric boundary conditions of the waveguide, and the gap between the waveguide and the other waveguide or circuit board. This can make waveguide designs unusable or require welding during assembly.

[0012] Disclosure of the invention

[0013] The waveguide has a recess formed in a sidewall of a waveguide channel. The recess is preferably formed perpendicular to the sidewall and forms a cavity in the sidewall. The recess can have various shapes, for example, rectangular, round, conical, or similar. The width and height of the recess in the sidewall are substantially smaller than half the wavelength of a free-space signal (<ΔQ / 2) for which the at least one waveguide channel is designed. The wavelength of the free-space signal 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 free-space signal wavelength (<ΔQ / 2). The position and depth of the recess can essentially be freely selected, as long as the condition is met that the width and height are substantially smaller than half the free-space signal wavelength.Due to the dimensions of the recess, the propagation mode in the waveguide channel is neither influenced by the recess nor does it interact, so that the power of the propagation mode is not changed because the cutoff frequency for the recess is not reached.

[0014] According to one aspect, the recess is provided in a waveguide consisting of two joined waveguide parts and is positioned at the joint. The parallel plate mode forms in the gap between the two waveguide bodies of the waveguide parts, which is caused by imperfect joining.

[0015] According to a further aspect, a recess is provided in a system comprising a waveguide and a further waveguide or a circuit board connected to the waveguide. The waveguide of the system can generally be any type of waveguide, i.e., it can be the waveguide described above, which consists of two waveguide parts, or it can be a one-piece waveguide and has at least one waveguide channel. The further waveguide or the circuit board is connected to the waveguide on the outside of the waveguide, where the output of the waveguide channel is located. The output of the waveguide channel is the opening through which the signal is coupled out of or into the waveguide - therefore, an input of the waveguide channel is also considered an output here.Specifically, the opening of a portion of the waveguide channel that is closed when joining to form the waveguide channel is not considered an exit. The parallel plate mode forms at a gap in the junction between the waveguide body of the waveguide and the waveguide body of the other waveguide, or at a coupling point on the printed circuit board. The recess can be considered a stub. As a result, the propagation characteristics of the parallel plate mode at the surface of the waveguide body are changed, shifting the resonant frequency or attenuating the resonance. By positioning and selecting the number of recesses, the resonant frequencies of the waveguide bodies can be controlled and removed within the relevant frequency band. As a result, energy leakage from the waveguide is reduced.

[0016] Preferably, the recess is provided on the surface of the waveguide body through which the joining or connection is realized and on which the parallel plate mode is generated. When joining the waveguide parts, the relevant surface of the waveguide body is the one facing the other waveguide part and into which the part of the at least one waveguide channel is machined. When connecting to another waveguide or a printed circuit board, the relevant surface is the one that has the output of the waveguide channel. There, the propagation properties of the parallel plate mode can be effectively modified. Furthermore, the surface is easily accessible for external processing.

[0017] In the case of a waveguide consisting of two waveguide parts, a recess is preferably formed on the respective surface of each of the two waveguide parts. The positions and shapes of the recesses correspond. When the waveguide parts are joined, the recesses of the two waveguide parts fit together such that they form a common recess in at least one waveguide channel. This allows the recess to be easily provided during the manufacture of the waveguide parts. Furthermore, in this case, the recess is arranged symmetrically in the waveguide channel.

[0018] It is also possible to form several recesses in the sidewall, arranged side by side and preferably at the same height. This allows the parallel plate modes to be selectively and particularly effectively suppressed. The recess is particularly advantageous in the waveguide channel configurations described below, but can be applied to any configuration.

[0019] In one embodiment, the waveguide consisting of two waveguide parts has a bent or kinked waveguide channel surrounding a region in which a resonant cavity can form in the gap between the two waveguide parts. Resonance forms when one dimension of the resonant cavity corresponds approximately to half the free-space wavelength (or a multiple thereof) of the signal propagating through the waveguide channel (I ~ AQ / 2). The recess is preferably arranged in this region of the waveguide body of the first waveguide part surrounded by the bent or kinked waveguide channel. This destroys the resonant cavity and significantly reduces the parallel plate mode in the gap between the waveguide bodies. In general, any waveguide shape surrounding such a region in which a resonant cavity can form can be relevant.The following shapes are particularly relevant: a U-shaped waveguide channel, in which the waveguide channel runs parallel on both legs, a V-shaped waveguide channel or an L-shaped waveguide channel, in which the legs are angled to each other.

[0020] In a further embodiment, the waveguide consisting of two waveguide sections has two parallel waveguide channels. In the region of the waveguide body between the two parallel waveguide channels, a resonant cavity can form in the gap between the two waveguide sections. In addition, unwanted energy coupling can occur between the two waveguide channels. Resonance forms when the distance between the two parallel waveguide channels corresponds approximately to half the free-space wavelength (or a multiple thereof) of the signal propagating through the waveguide channel (I ~ AQ / 2). For this embodiment, several adjacent cutouts are particularly advantageous. This destroys the resonant cavity and significantly reduces the parallel plate mode in the gap between the waveguide bodies. Furthermore, this prevents energy coupling between the waveguide channels across the gap.The recess is also particularly advantageous when the waveguide has a choke at the connection to the further waveguide or the circuit board. The choke is used to reduce leakage, especially when the connection is not made by welding. However, such a choke only works optimally with perfect symmetry. Any misalignment of the waveguide to the further waveguide or to the coupling point of the circuit board destroys the symmetry and causes resonances on the surface of the waveguide body between the waveguide channel and the choke. The recess is preferably formed in the sidewall of the waveguide channel that is located towards the choke. Preferably, the recess penetrates the sidewall and connects the choke to the waveguide channel. This destroys the resonance between the waveguide channel and the choke.

[0021] Short description of the drawings

[0022] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

[0023] Figure 1 shows a sectional view of a waveguide assembled from two waveguide parts with a waveguide channel.

[0024] Figure 2 shows a sectional view of a recess in the waveguide according to an embodiment of the invention.

[0025] Figure 3 shows an isometric view of the top side of a waveguide part of an embodiment of the waveguide according to the invention with a first configuration of a waveguide channel.

[0026] Figure 4 shows an isometric view of the top side of a waveguide part of an embodiment of the waveguide according to the invention with a second configuration of a waveguide channel.

[0027] Figure 5 shows an isometric view of a front side of another embodiment of the waveguide according to the invention with a choke at the exit of the waveguide channel. Embodiments of the invention

[0028] Figure 1 shows a waveguide 1 consisting of two waveguide parts 11, 12. The first waveguide part 11 has a waveguide body 111 in which a recess 110 is formed, which in this example has a rectangular cross-section and extends in the third direction through the waveguide body 111. Similarly, the second waveguide part 12 has a waveguide body 121 in which a recess 120 is formed, which in this example has the same shape as the aforementioned recess 110 of the first waveguide part 11. Outside the recesses, the waveguide bodies 111, 121 have opposing surfaces 112 and 122 that run parallel to each other. To assemble the waveguide 1, the two waveguide parts

[0029] II, 12 are joined together at these surfaces 112 and 122. In addition to welding, gluing or screwing can be used as joining methods. By joining, the two recesses 110 and 120 together form a waveguide channel 10 designed as a rectangular waveguide, in which electromagnetic signals (not shown here) can be guided. This means that the recesses 110, 120 are parts of the waveguide channel 10, which, when separated, can be easily integrated into the waveguide bodies, for example, by milling or injection molding.

[0030] III, 121 can be formed and, when joined together, form the waveguide channel 10. By means of appropriately designed recesses 110, 120, different shapes of waveguide channels and also multiple waveguide channels can be formed in the same waveguide 1. Reference is made to Figures 3 and 4 for this purpose. During joining, a gap 13 can arise between the surfaces 112 and 122, which is shown disproportionately large in the present figures. Since the two surfaces 112 and 122 are parallel to one another, a parallel plate mode can form in the gap 13. This leads to a leakage, represented by the arrows 131, of electromagnetic energy of the signals guided in the waveguide channel 10, whereby the energy of the signal in the waveguide channel 10 decreases.

[0031] In the other figures, identical components are identified by identical reference numerals and reference is made to the above description for an explanation thereof. Figure 2 shows a section of the waveguide 1 according to the invention, which is constructed as shown in Figure 1. The waveguide 1 according to the invention has a recess 2 which extends perpendicularly from the waveguide channel 10 into the waveguide bodies 111, 121 and is formed symmetrically to the gap 13. The first waveguide part 11 has a rectangular recess 21 on its surface 112 in a side wall 114 of the waveguide channel 10 - ie the recess 110 which represents the part of the waveguide channel 10. The second waveguide part 12 has a side wall 124 of the waveguide channel 10 - iethe recess 120, which represents the other part of the waveguide channel 10 - has a rectangular cutout 22 on its surface 122, which corresponds to the cutout 21 in the first waveguide part 12 and is arranged in the same position. By joining the waveguide parts 11, 12, the two cutouts 21 and 22 together form the common cutout 2, which here has a cuboid shape. In other embodiments not shown here, the cutout 2 can also take on other shapes, for example a cylindrical shape. The cutout 2 has a height h that is significantly smaller than the wavelength of the signal in free space (h « Ao) and here, for example, is a quarter of the wavelength of the signal in free space (h = AQ / 4).In addition, the recess has a width d (this is not shown in Figure 2 because it extends into the plane of the sheet; see Figures 3 and 4), which is also considerably smaller than the wavelength of the signal in free space (d « Ao) and here, for example, is also a quarter of the wavelength of the signal in free space (b = AQ / 4).

[0032] Figures 3 and 4 each show exemplary embodiments of the waveguide 1 according to the invention with different configurations of the waveguide channel 10. Figures 3 and 4 each show an isometric view from above of the first waveguide part 11. The second waveguide part 12 is not shown for reasons of clarity, but is designed identically to the first waveguide part 11.

[0033] In Figure 3, the waveguide channel 10 is U-shaped and has a base section 101 and two parallel leg sections 102, 103. The base section 101 and the leg sections 102 and 103 surround a region of the waveguide body 111 on three sides. If the length I of this region of the waveguide body 111 between the leg sections 102, 103, i.e. the distance between the leg sections 102, 103, is close to half the wavelength of the signal in free space (I ~ KJ2), a resonant cavity can form in the gap 13 between the parallel waveguide bodies 111 and 121 in the surrounding region, which amplifies the leakage of the electromagnetic energy. In other embodiments not shown, the waveguide channel may be V-shaped or L-shaped and may also surround an area in which a resonant cavity may form.

[0034] According to the invention, a plurality of cutouts (here four) 23 to 26 are provided in the side wall 114 of one leg section 102 of the waveguide channel 10 in the direction of the surrounding area. As shown with reference to Figure 2, these cutouts 23 to 25, together with the cutouts of the second waveguide part 12 (not shown), form common cutouts. The cutouts 23 to 26 each have the same width b and the same height h, which are each significantly smaller than half the wavelength of the signal in free space and here, for example, amount to a quarter of the wavelength of the signal, and they are each arranged at the same distance d, which here, for example, corresponds approximately to half the wavelength of the signal (d ~ Ao / 2). The cutouts 23 to 26 change the geometric boundary conditions so that the parallel plate mode is suppressed and no or only minimal leakage occurs.

[0035] Figure 4 shows two waveguide channels 10 and 100 that run parallel to each other. The waveguide channels enclose a region of the waveguide body 111 from two opposite sides. If the length I of this region of the waveguide body 111 between the waveguide channels 10, 100, i.e., the distance between the waveguide channels 10, 100, is close to half the wavelength of the signal in one of the waveguide channels 10, 100 (I ~ KJ2), a resonant cavity can form in the gap 13 between the parallel waveguide bodies 111 and 121 in the surrounding region, which amplifies the leakage of electromagnetic energy. According to the invention, several recesses (here four) 23 to 26 are provided in the side wall 114 of one leg section 102 of the waveguide channel 10 in the direction of the other waveguide channel 100 and the surrounding region.As shown in Figure 2, these recesses 23 to 26, together with the recesses of the second waveguide part 12 (not shown), form common recesses. The recesses 23 to 26 each have the same width b and the same height h, which are each significantly smaller than half the wavelength of the signal in free space and here, for example, amount to a quarter of the wavelength of the signal, and they are each arranged at the same distance d, which here, for example, corresponds approximately to half the wavelength of the signal (d ~ Ao / 2). The recesses 23 to 26 change the geometric boundary conditions so that the parallel plate mode is suppressed and no or only minimal leakage occurs.

[0036] Figure 5 shows a view of the front side of a waveguide 3. The waveguide 3 can be the waveguide 1 described above, consisting of two waveguide parts. In general, the waveguide 3 can also be formed in a different way, e.g., in one piece. The waveguide 3 has a waveguide body 31 and, within this, a waveguide channel 30 designed as a rectangular hollow guide. The output of the waveguide channel 30 is located on the surface 32 of the waveguide body 31 facing the front side. The waveguide 3 is connected via this surface 32 to another waveguide (not shown here) or to a circuit board (likewise not shown), so that signals are coupled into or out of the further waveguide or a coupling point on the circuit board via the output of the waveguide channel 30.At the exit of the waveguide channel 30, a choke 4 is provided, which surrounds the waveguide channel 30. According to the invention, two recesses 27 and 28 are provided in the side wall 34 of the waveguide channel 30 on the surface 32, which are opposite one another and arranged parallel to one another. In this example, the recesses 27, 28 are each formed on the long sides of the rectangular waveguide channel 30. In other, not shown, embodiments, a different number and arrangement of the recesses is provided; for example, two recesses can be provided on each of the long sides and two recesses on each of the short sides. The recesses 27, 28 penetrate the side wall 34 and thus connect the waveguide channel 30 and the choke 4.As a result, a resonance that would form between the waveguide channel 30 and the choke 4 in the gap between the surface 32 of the waveguide body 32 of the waveguide 3 and the further waveguide or the circuit board is interrupted and no or only a slight leakage occurs.

Claims

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

2. Waveguide (1) according to claim 1, characterized in that the recess (2, 23 - 26) is formed perpendicular to the side wall (114, 124) in the latter.

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

4. Waveguide (1) according to claim 3, characterized in that in each waveguide part (11, 12) a recess (21, 22) is formed on the respective surface (112, 122) and that the positions of the recesses (21, 22) correspond so that in the assembled state of the waveguide (1) the recesses (21, 22) fit together so that they form a common recess (2).

5. Waveguide (1) according to one of the preceding claims, characterized in that a waveguide part (11, 12) has a plurality of recesses (23 - 26) which are arranged next to one another. Waveguide (1) according to one of the preceding claims, wherein the waveguide (1) has a bent or kinked waveguide channel (101, 102, 103) surrounding a region, characterized in that the recess (2, 23-26) is formed in the region of the waveguide body (111, 121) surrounded by the bent or kinked waveguide channel (101, 102, 103). Waveguide (1) according to one of the preceding claims, wherein the waveguide (1) has two parallel waveguide channels (10, 100), characterized in that the recess (2, 23-26) is formed in the side wall (114) of one waveguide channel (10) in the direction of the other waveguide channel (100).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 to the further waveguide or to the circuit board at the output, characterized in that a recess (27, 28) is formed in a side wall (34) of the at least one waveguide channel (30), wherein the width (b) and the height (h) of the recess (27, 28) are smaller than half the wavelength of a signal for which the at least one waveguide channel (30) is designed. System according to claim 8, characterized in that the recess (27, 28) is formed in the side wall (34) perpendicular to the latter. System according to claim 8 or 9, characterized in that the recess (27, 28) is formed on the surface (32) of the waveguide body (31).System according to one of claims 8 to 10, characterized in that the waveguide (1) has a plurality of recesses (27, 28). System according to one of claims 8 to 11, wherein the waveguide (1) has a choke (4), characterized in that the recess (27, 28) 28) is formed in the side wall (34) of the waveguide channel (30) towards the throttle (4).

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