A cascaded broadband choke for drive shafts in waveguides

Abstract

This invention relates to the field of microwave transmission technology and provides a cascaded broadband choke device for a drive shaft in a waveguide. The device includes a drive shaft and a waveguide wall. The waveguide wall has a hollow, cylindrical structure. The drive shaft penetrates the waveguide wall longitudinally without contacting it. At least one interlayer is disposed inside the waveguide wall, which sequentially divides the interior of the waveguide wall into multiple cavities along the axial direction of the drive shaft. The drive shaft penetrates the interlayer without contacting it. A dielectric sheet is disposed within each cavity, with its outer wall in close contact with the inner wall of the cavity. The drive shaft penetrates the dielectric sheet without contacting it. The choke device provided by this invention uses an interlayer to divide the interior of the waveguide wall into multiple different cavities, and a dielectric sheet is disposed separately in each cavity. This allows the choke device to form a cascaded, multi-layered choke structure, improving the choke effect while widening the operating frequency band of the choke device.

Description

Technical Field

[0001] This invention relates to the field of microwave transmission technology, and more specifically, to a cascaded broadband choke device for a drive shaft in a waveguide. Background Technology

[0002] For systems such as array antennas and radar, the interconnection between the feed system and various components inevitably causes microwave leakage. Suppressing microwave leakage is a crucial issue for ensuring the stable operation of the entire system. Chokes are devices that prevent microwave leakage and are widely used in the interconnection of microwave antenna feed systems and rotating joints in mechanically scanned radar antennas. Different applications place different demands on the design of chokes.

[0003] With the development and in-depth research of mechatronics, mechanical transmission devices are increasingly used in microwave systems, with the introduction of drive shafts into waveguides being a common example. In this case, a certain gap needs to be left between the drive shaft and the waveguide wall to ensure proper rotation of the drive shaft. However, these gaps can lead to discontinuities in the waveguide structure, resulting in microwave leakage problems that severely impact the waveguide's standing wave ratio, loss, and power capacity.

[0004] Currently, there are very few choke devices applicable to drive shafts in waveguides. Zhang Jianqiong et al. first proposed a choke device for mechanical drive shafts. The inner wall of the choke device forms two quarter-wavelength transmission lines between the outer shell and the drive shaft, respectively. After impedance transformation through these two transmission lines, an electrical short circuit is formed at the top of the choke device's outer shell, thereby suppressing microwave leakage [Zhang Jianqiong, Liu Qingxiang, Li Xiangqiang, Zhao Liu, A Small Broadband Choke Device for Drive Shafts in Waveguide Systems, Sichuan: CN101702456A, 2010]. However, due to the limitation of the quarter-wavelength length requirement, its size is difficult to reduce, thus limiting its application in situations with strict size requirements. To address this, Li Xiangqiang et al. designed an ultra-miniature choke device that effectively reduces its size by using dielectric filling in the impedance section [Li Xiangqiang, Zhang Jianqiong, Liu Qingxiang, Liu Qing, An Ultra-Miniature Choke Device for Drive Shafts in Waveguides, Sichuan: CN205657149U, 2016]. However, its relative bandwidth for leakage loss less than -30dB is only 10.4%, and its relative bandwidth for leakage loss less than -40dB is only 3.2%, which cannot meet the wide bandwidth requirements of microwave transmission. Therefore, it is of great significance to study a broadband choke device for drive shafts in waveguides. Summary of the Invention

[0005] The purpose of this invention is to provide a cascaded broadband choke device for drive shafts in waveguides. It effectively solves the problem of microwave leakage at the drive shaft inlet after the drive shaft enters the waveguide, and has the characteristics of being cascadeable, having a wide bandwidth, small size, easy to process, and low microwave leakage.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A cascaded broadband choke device for a drive shaft in a waveguide includes a drive shaft and a waveguide wall, wherein the waveguide wall has a hollow cylindrical structure, and the drive shaft penetrates the waveguide wall longitudinally without contacting the waveguide wall.

[0008] The waveguide wall has at least one interlayer inside, which is used to divide the interior of the waveguide wall into multiple accommodating cavities along the axial direction of the drive shaft. The drive shaft passes through the interlayer but does not contact the interlayer.

[0009] A medium sheet is disposed inside the accommodating cavity, the outer wall of the medium sheet is in close contact with the inner wall of the accommodating cavity, and the drive shaft passes through the medium sheet but does not contact the medium sheet.

[0010] The working principle of this invention is as follows: a dielectric sheet located in the accommodating cavity forms a radial impedance segment, while the gap between the dielectric sheet, the interlayer, and the drive shaft forms an axial impedance segment. After impedance transformation of the two impedance segments, an electrical short circuit can be formed at the microwave leakage point, thereby suppressing microwave leakage. In other words, according to the impedance transformation principle, a dielectric sheet and an interlayer form a choke structure. By using the dielectric sheet and the interlayer alternately, multiple dielectric sheets and interlayers form a cascade of multiple choke structures, which can effectively improve the choke effect of the choke device and broaden the operating frequency band of the choke device.

[0011] It should be noted that the outer diameter of each dielectric layer in the choke device can be the same or different. By changing the outer diameter of the dielectric layer, the operating frequency of each choke structure can be changed. Specifically, when the outer diameter of each dielectric layer is the same, each choke structure operates at the same frequency, which can effectively improve the choke performance of the choke device. When the outer diameter of each dielectric layer is different, each choke structure operates at a different frequency, which can effectively broaden the operating frequency band of the choke device.

[0012] In some possible embodiments, the number of the interlayer is one, which sequentially divides the interior of the waveguide wall along the axial direction of the drive shaft into two accommodating cavities of the same size.

[0013] In some possible embodiments, there are two interlayers, which sequentially divide the interior of the waveguide wall along the axial direction of the drive shaft into three accommodating cavities of the same size.

[0014] In some possible embodiments, the waveguide wall has an abutment step inside, and there is one interlayer. The upper surface of the interlayer is in close contact with the lower surface of the abutment step. The interlayer divides the interior of the waveguide wall into two accommodating cavities, one smaller at the top and one larger at the bottom, along the axial direction of the drive shaft.

[0015] In some possible embodiments, the dielectric sheet is made of an insulating medium with a high dielectric constant, preferably, the dielectric sheet is made of 95% alumina ceramic with a dielectric constant of 9.0.

[0016] In some possible embodiments, the waveguide wall includes a housing and a base, the bottom of the housing having an open structure, the base being stepped and having a positioning groove, and the bottom of the housing being embedded in the positioning groove.

[0017] In some possible embodiments, the top of the housing has a first circular hole for the drive shaft to pass through, the base has a second circular hole for the drive shaft to pass through, the interlayer has a third circular hole for the drive shaft to pass through, and the medium sheet has a fourth circular hole for the drive shaft to pass through. The housing, base, interlayer, medium sheet and drive shaft are coaxially arranged.

[0018] In some possible embodiments, the first, second, third, and fourth circular holes have the same diameter.

[0019] In some possible embodiments, the drive shaft, housing, base, and interlayer are all made of metal.

[0020] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0021] 1. The choke device provided by the present invention divides the interior of the waveguide wall into multiple different accommodating cavities by using a sandwich structure, and separately sets a dielectric sheet in each accommodating cavity, so that the choke device can form a cascaded multi-layer choke structure, which improves the choke effect of the choke device and widens the operating frequency band of the choke device.

[0022] 2. The choke device provided by the present invention has a simple structure and is easy to manufacture and implement. In practical applications, only the material and size of the dielectric sheet need to be changed to make the choke device suitable for different operating frequency bands and occasions. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of the choke device provided in Embodiment 1 of the present invention;

[0024] Figure 2 This is a cross-sectional view of the choke device from Example 1 used in a radial line feed system introduced into a drive shaft.

[0025] Figure 3 This is a microwave leakage loss diagram of one of the coupling outlets when the choke device in Example 1 is used in a radial line feed system introduced into a drive shaft.

[0026] Figure 4 This is a cross-sectional view of the choke device provided in Embodiment 2 of the present invention;

[0027] Figure 5 This is a microwave leakage loss diagram of one of the coupling outlets when the choke device in Example 2 is used in a radial line feed system introduced into a drive shaft.

[0028] Figure 6 This is a cross-sectional view of the choke device provided in Embodiment 3 of the present invention;

[0029] Figure 7 This is a microwave leakage loss diagram of one of the coupling outlets when the choke device in Example 3 is used in a radial line feed system introduced into a drive shaft.

[0030] Icons: 1-Drive shaft, 2-Waveguide wall, 21-Housing, 21a-First circular hole, 21b-Abutting step, 22-Base, 22a-Positioning groove, 22b-Second circular hole, 3-Interlayer, 3a-Third circular hole, 4-Dielectric sheet, 4a-Fourth circular hole, 41-First dielectric sheet, 42-Second dielectric sheet, 5-Radial line feed system, 5a-Top plate, 5b-Bottom plate, 6-Output coaxial. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following examples.

[0032] Please refer to Figures 1 to 7 This invention provides a cascaded broadband choke device for a drive shaft in a waveguide, comprising a drive shaft 1 and a waveguide wall 2, wherein the waveguide wall 2 has a hollow cylindrical structure, and the drive shaft 1 extends longitudinally through the waveguide wall 2 without contacting it. Specifically, as shown... Figure 1 , Figure 4 or Figure 6 As shown, the waveguide wall 2 includes a housing 21 and a base 22. The bottom of the housing 21 has an open structure, and the base 22 is stepped and has a positioning groove 22a. The bottom of the housing 21 is embedded in the positioning groove 22a to achieve reliable positioning of the housing 21. The top of the base 22 extends into the interior of the housing 21 to press the bottom dielectric sheet 4 against it.

[0033] Understandably, in order for the drive shaft 1 to penetrate the waveguide wall 2 longitudinally without contacting it, the following steps are continued... Figure 1 , Figure 4 or Figure 6The top of the housing 21 has a first circular hole 21a for the transmission shaft 1 to pass through, and the base 22 has a second circular hole 22b for the transmission shaft 1 to pass through. The first circular hole 21a and the second circular hole 22b are respectively located at the center of the top of the housing 21 and the center of the base 22, so that the transmission shaft 1, the housing 21 and the base 22 are coaxially arranged. Preferably, the diameters of the first circular hole 21a and the second circular hole 22b are the same.

[0034] At this point, in order to achieve the formation of a cascaded multi-layer choke structure within waveguide wall 2, combined with Figure 1 , Figure 4 or Figure 6 As shown, the waveguide wall 2 has at least one interlayer 3 inside. The interlayer 3 is used to divide the interior of the waveguide wall 2 into multiple accommodating cavities along the axial direction of the drive shaft 1. Specifically, at least one interlayer 3 is horizontally disposed inside the housing 21 to divide the interior of the housing 21 into multiple accommodating cavities along the axial direction of the drive shaft 1. At this time, the drive shaft 1 passes through the interlayer 3 and does not contact the interlayer 3.

[0035] Meanwhile, each accommodating cavity separated by the interlayer 3 is individually equipped with a dielectric sheet 4, and the outer wall of the dielectric sheet 4 is in close contact with the inner wall of the accommodating cavity (i.e., the dielectric sheet 4 fills the entire accommodating cavity). At this time, the drive shaft 1 passes through the dielectric sheet 4 but does not contact it. It should be noted that the dielectric sheet 4 is made of an insulating medium with a high dielectric constant. Preferably, the dielectric sheet 4 is made of 95% alumina ceramic with a dielectric constant of 9.0. By using an insulating medium with a high dielectric constant to make the dielectric sheet 4, the microwave transmission distance can be shortened, thereby further reducing the size of the choke device.

[0036] Understandably, in order for the drive shaft 1 to longitudinally penetrate the interlayer 3 and the medium sheet 4 without contacting them, the following reference is continued. Figure 1 , Figure 4 or Figure 6 The interlayer 3 and the medium sheet 4 are also cylindrical structures. Specifically, the interlayer 3 has a third circular hole 3a for the transmission shaft 1 to pass through, and the medium sheet 4 has a fourth circular hole 4a for the transmission shaft 1 to pass through. The third circular hole 3a and the fourth circular hole 4a are respectively located at the center of the interlayer 3 and the center of the medium sheet 4, so that the housing 21, the base 22, the interlayer 3, the medium sheet 4 and the transmission shaft 1 are coaxially arranged. Preferably, the diameter of the third circular hole 3a and the fourth circular hole 4a is the same as the diameter of the first circular hole 21a and the second circular hole 22b. The housing 21, the base 22, the interlayer 3 and the transmission shaft 1 are all made of metal.

[0037] The working principle of the choke device provided in this embodiment is as follows: a dielectric sheet 4 located in the accommodating cavity forms a radial impedance segment, while the gap between a dielectric sheet 4, a sandwich layer 3 and the drive shaft 1 forms an axial impedance segment. By transforming the impedance of the two impedance segments, an electrical short circuit can be formed at the microwave leakage point, thereby suppressing microwave leakage. In other words, according to the impedance transformation principle, a dielectric sheet 4 and a sandwich layer 3 form a choke structure. By using the dielectric sheet 4 and the sandwich layer 3 alternately, multiple dielectric sheets 4 and sandwich layers 3 form a cascade of multiple choke structures, which can effectively improve the choke effect of the choke device and broaden the operating frequency band of the choke device.

[0038] It should be noted that the outer diameter of the dielectric sheet 4 in each layer of the choke device can be the same or different. By changing the outer diameter of the dielectric sheet 4, the operating frequency of each choke structure can be changed. Specifically, when the outer diameter of each dielectric sheet 4 is the same, each choke structure operates at the same frequency, which can effectively improve the choke performance of the choke device. When the outer diameter of each dielectric sheet 4 is different, each choke structure operates at a different frequency, which can effectively broaden the operating frequency band of the choke device.

[0039] To provide a clearer and more intuitive understanding of the choke device provided by the present invention, the following will further elaborate on the choke device in conjunction with different embodiments.

[0040] Example 1

[0041] In this embodiment, combined with Figure 1 As shown, there is one interlayer 3 inside the housing 21. The interlayer 3 divides the interior of the waveguide wall 2 housing 21 into two accommodating cavities of the same size along the axial direction of the drive shaft 1. At this time, the dielectric sheet 4 in the two accommodating cavities is the same size, so that the choke device forms a cascaded double-layer choke structure with the same frequency.

[0042] Figure 2 The diagram shows a cross-sectional view of the choke device used in a radial feed system 5 with a drive shaft 1. Only one coupling outlet is shown in the diagram: microwaves are transmitted in the radial feed system 5, which consists of a top plate 5a and a bottom plate 5b. In the radial feed system 5, the drive shaft 1 driven by a motor passes through the radial feed system 5 and forms a coupling outlet with the outer wall of the output coaxial 6, thereby outputting microwaves. The choke device is fitted at the junction of the drive shaft 1 and the bottom plate 5b of the radial feed system 5, so that the upper surface of the shell 21 of the cylindrical waveguide wall 2 is fixed to the bottom plate 5b, thereby fixing the choke device and the radial feed system 5 together.

[0043] When the microwave operating frequency is 12.5GHz, the specific dimensions of the drive shaft 1, the interlayer 3, and the dielectric sheet 4 in this embodiment are as follows: the diameter of the drive shaft 1 is 2.5mm, the outer diameter of the interlayer 3 is 8mm, the height of the interlayer 3 is 0.5mm, the diameter of the third circular hole 3a (i.e., the inner diameter of the interlayer 3) on the interlayer 3 is 3mm, the outer diameter of the dielectric sheet 4 is 8mm, the height of the dielectric sheet 4 is 1.5mm, and the diameter of the fourth circular hole 4a (i.e., the inner diameter of the dielectric sheet 4) on the dielectric sheet 4 is 3mm.

[0044] like Figure 3 As shown, numerical simulation results indicate that the leakage loss is less than -40dB and the relative bandwidth is 13.2% in the 11.72-13.37GHz frequency band required by the radial feed system 5; and less than -60dB and the relative bandwidth is 4.24% in the 12.14-12.67GHz frequency band required by the radial feed system 5. This demonstrates that the choke device has a good effect on suppressing microwave leakage in the wide frequency band of the radial feed system 5.

[0045] Example 2

[0046] In this embodiment, combined with Figure 4 As shown, there are two interlayers 3 inside the housing 21. The two interlayers 3 divide the interior of the waveguide wall 2 housing 21 into three accommodating cavities of the same size along the axial direction of the drive shaft 1. At this time, the dielectric sheets 4 in the three accommodating cavities are of the same size, so that the choke device forms a cascaded three-layer choke structure with the same frequency.

[0047] Meanwhile, the choke device is used in the same manner as in Example 1 in a radial line power supply system 5 introduced into the drive shaft 1.

[0048] When the microwave operating frequency is 12.5GHz, the specific dimensions of the drive shaft 1, the interlayer 3, and the dielectric sheet 4 in this embodiment are as follows: the diameter of the drive shaft 1 is 2.5mm, the outer diameter of the interlayer 3 is 8mm, the height of the interlayer 3 is 0.5mm, the diameter of the third circular hole 3a (i.e., the inner diameter of the interlayer 3) on the interlayer 3 is 3mm, the outer diameter of the dielectric sheet 4 is 8mm, the height of the dielectric sheet 4 is 1.5mm, and the diameter of the fourth circular hole 4a (i.e., the inner diameter of the dielectric sheet 4) on the dielectric sheet 4 is 3mm.

[0049] like Figure 5As shown, numerical simulation results indicate that the leakage loss is less than -60dB within the 11.75-12.97GHz frequency band required by the radial feed system 5, with a relative bandwidth of 9.76%; the leakage loss at the center frequency of 12.5GHz is -95dB. It can be seen that the choke device has a significantly improved choke effect compared to the choke device with a cascaded double-layer choke structure provided in Example 1.

[0050] Example 3

[0051] In this embodiment, combined with Figure 6 The contents shown also have one interlayer 3 inside the housing 21. The difference from embodiment 1 is that the housing 21 of the waveguide wall 2 is provided with an abutting step 21b, and the upper surface of the interlayer 3 is in close contact with the lower surface of the abutting step 21b, so that the housing 21 of the waveguide wall 2 is divided into two accommodating cavities with a smaller upper cavity and a larger lower cavity along the axial direction of the transmission shaft 1 by the interlayer 3. At this time, the dielectric sheet 4 in the two accommodating cavities is different in size. Specifically, the outer diameter of the dielectric sheet 4 in the two accommodating cavities is different, so that the choke device forms a cascaded double-layer choke structure with different frequencies.

[0052] Meanwhile, the choke device is used in the same manner as in Embodiment 1 in a radial line power supply system 5 introduced into the drive shaft 1. For ease of explanation, in this embodiment, the dielectric sheet 4 disposed in the upper and smaller accommodating cavity is named the first dielectric sheet 41, and the dielectric sheet 4 disposed in the lower and larger accommodating cavity is named the second dielectric sheet 42.

[0053] When the microwave operating frequency is 12.5GHz, the specific dimensions of the drive shaft 1, interlayer 3, first dielectric sheet 41, and second dielectric sheet 42 in this embodiment are as follows: the diameter of the drive shaft 1 is 2.5mm, the outer diameter of the interlayer 3 is 8mm, the height of the interlayer 3 is 0.5mm, the diameter of the third circular hole 3a (i.e., the inner diameter of the interlayer 3) on the interlayer 3 is 3mm, the outer diameter of the first dielectric sheet 41 is 7.9mm, the height of the first dielectric sheet 41 is 1.5mm, the diameter of the fourth circular hole 4a (i.e., the inner diameter of the first dielectric sheet 41) on the first dielectric sheet 41 is 3mm, the outer diameter of the second dielectric sheet 42 is 8mm, the height of the second dielectric sheet 42 is 1.5mm, and the diameter of the fourth circular hole 4a (i.e., the inner diameter of the second dielectric sheet 42) on the second dielectric sheet 42 is 3mm.

[0054] like Figure 7As shown, numerical simulation results indicate that the leakage loss is less than -40dB and the relative bandwidth is 13.6% in the 11.80-13.50GHz frequency band required by the radial feed system 5; and the leakage loss is less than -60dB and the relative bandwidth is 4.8% in the 12.22-12.82GHz frequency band required by the radial feed system 5. It can be seen that the operating frequency band of this choke device is further widened compared with the choke device with cascaded double-layer same-frequency choke structure provided in Example 1.

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cascaded broadband choke device for a drive shaft in a waveguide, comprising a drive shaft and a waveguide wall, wherein the waveguide wall has a hollow cylindrical structure, and the drive shaft extends longitudinally through the waveguide wall without contacting it, characterized in that, The waveguide wall has at least one interlayer inside, which is used to divide the interior of the waveguide wall into multiple accommodating cavities along the axial direction of the drive shaft. The drive shaft passes through the interlayer but does not contact it. The waveguide wall also has an abutting step inside. There is one interlayer, and the upper surface of the interlayer is in close contact with the lower surface of the abutting step. The interlayer divides the interior of the waveguide wall into two accommodating cavities, one smaller at the top and one larger at the bottom, along the axial direction of the drive shaft. A medium sheet is disposed inside the accommodating cavity, the outer wall of the medium sheet is in close contact with the inner wall of the accommodating cavity, and the drive shaft passes through the medium sheet but does not contact the medium sheet; Both the drive shaft and the interlayer are made of metal.

2. The cascaded broadband choke device for a drive shaft in a waveguide according to claim 1, characterized in that, The dielectric sheet is made of 95% alumina ceramic with a dielectric constant of 9.

0.

3. The cascaded broadband choke device for a drive shaft in a waveguide according to claim 1, characterized in that, The waveguide wall includes a housing and a base. The bottom of the housing has an open structure, and the base is stepped and has a positioning groove. The bottom of the housing is embedded in the positioning groove.

4. The cascaded broadband choke device for a drive shaft in a waveguide according to claim 3, characterized in that, The top of the housing has a first circular hole for the drive shaft to pass through, the base has a second circular hole for the drive shaft to pass through, the interlayer has a third circular hole for the drive shaft to pass through, and the medium sheet has a fourth circular hole for the drive shaft to pass through. The housing, base, interlayer, medium sheet and drive shaft are coaxially arranged.

5. The cascaded broadband choke device for a drive shaft in a waveguide according to claim 4, characterized in that, The first, second, third, and fourth circular holes have the same diameter.

6. The cascaded broadband choke device for a drive shaft in a waveguide according to claim 3, characterized in that, Both the housing and the base are made of metal.

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