Antenna device and ZigBee module

Abstract

The present invention provides an antenna device and a ZigBee module. The antenna device includes a feed source and a radiator. The radiator includes a first radiating portion and a second radiating portion. The first radiating portion is connected to the feed source. The first radiating portion has a first gap. The second radiating portion is connected to the first radiating portion, and the second radiating portion and the first radiating portion are arranged along an arc. The second radiating portion includes a first sub-radiating portion and a second sub-radiating portion that are connected to each other. The end of the first sub-radiating portion facing away from the second sub-radiating portion is connected to the first radiating portion, and a second gap is formed between the first radiating portion, the first sub-radiating portion, and the second sub-radiating portion. The second gap and the first gap are located on opposite sides of the radiator, and the second gap is located on the side of the radiator facing away from the center of the arc. In this way, the antenna device can operate in a specified frequency band, and while reducing the physical size of the antenna device, the antenna device has a higher antenna gain and better radiation efficiency, thereby improving the performance of the antenna device.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to an antenna device and a ZigBee module. Background Art

[0002] With the development of wireless communication technology, ZigBee technology has been widely accepted due to its low power consumption, low cost and low complexity. However, the performance of the antenna devices in most current ZigBee modules is poor and cannot meet the usage requirements. Summary of the Invention

[0003] An embodiment of the present invention provides an antenna device to improve at least one of the above problems.

[0004] The embodiments of the present invention achieve the above-mentioned objectives through the following technical solutions.

[0005] In a first aspect, an embodiment of the present invention provides an antenna device. The antenna device includes a feed source and a radiator. The radiator includes a first radiating portion and a second radiating portion. The first radiating portion is connected to the feed source. The first radiating portion has a first gap. The second radiating portion is connected to the first radiating portion, and the second radiating portion and the first radiating portion are arranged along an arc. The second radiating portion includes a first sub-radiating portion and a second sub-radiating portion that are connected to each other. An end of the first sub-radiating portion facing away from the second sub-radiating portion is connected to the first radiating portion, and a second gap is formed between the first radiating portion, the first sub-radiating portion, and the second sub-radiating portion. The second gap and the first gap are located on opposite sides of the radiator, and the second gap is located on the side of the radiator facing away from the center of the arc.

[0006] In some embodiments, the first radiating portion is provided with a first convex portion and a second convex portion on one side toward the arc center, wherein the first convex portion is connected to the feed source, and the second convex portion is connected to the first sub-radiating portion and forms a first gap with the first convex portion.

[0007] In some embodiments, the distance between the first protrusion and the second protrusion is 1.4 to 3.1 mm.

[0008] In some embodiments, the first sub-radiating portion is arc-shaped, and a wiring width of the first sub-radiating portion is 1.4-1.5 mm.

[0009] In some embodiments, the second sub-radiating portion includes a first radiating segment and a second radiating segment. One end of the first radiating segment is connected to an end of the first sub-radiating portion away from the first radiating portion, and the other end of the first radiating portion is connected to the second radiating segment. The wiring width of the second radiating segment along the arc is greater than the wiring width of the first radiating segment along the arc.

[0010] In some embodiments, the wiring width of the first radiation segment along the arc direction is 0.9-1.1 mm, and the wiring width of the second radiation segment along the arc direction is 1.9-2.1 mm.

[0011] In some embodiments, the wiring length of the first radiation segment along the radial direction of the arc is 1.9 to 2.1 mm. The wiring length of the second radiation segment along the radial direction of the arc is 2.9 to 3.1 mm.

[0012] In some embodiments, the feed source, the first radiating portion, and the second radiating portion are arranged sequentially along an arc.

[0013] In some embodiments, the feed source includes a gold-plated layer, and the length of the gold-plated layer along the radial direction of the arc is 5.9 to 6.1 mm, and the width of the gold-plated layer along the direction of the arc is 2.9 to 3.1 mm.

[0014] Embodiments of the present invention also provide a ZigBee module. The ZigBee module includes a circuit board and an antenna device according to any of the aforementioned embodiments. The circuit board is provided with a first positioning hole. The antenna device is mounted on the circuit board. The first radiating portion is provided with a second positioning hole, the second positioning hole being coaxially arranged with the first positioning hole.

[0015] An antenna device and a ZigBee module are provided in accordance with an embodiment of the present invention. The antenna device includes a feed source and a radiator, wherein the feed source feeds a current signal into the radiator so that the radiator operates in a specified frequency band. The radiator includes a first radiating portion and a second radiating portion, wherein the first radiating portion is connected to the feed source, and the first radiating portion has a first gap, which is beneficial for reducing the frequency of the antenna device. The first radiating portion is connected to the first radiating portion, and the second radiating portion and the first radiating portion are arranged along an arc. The end of the first sub-radiating portion facing away from the second sub-radiating portion is connected to the first radiating portion, and a second gap is formed between the first radiating portion, the first sub-radiating portion, and the second sub-radiating portion. The second gap and the first gap are located on opposite sides of the radiator, and the second gap is located on the side of the radiator facing away from the center of the arc, so that the second sub-radiating portion can operate in a specified frequency band, and while reducing the physical size of the antenna device, the antenna device has a higher antenna gain and better radiation efficiency, thereby improving the performance of the antenna device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 A schematic structural diagram of an antenna device provided in an embodiment of the present invention is shown.

[0018] Figure 2 A schematic diagram showing the dimensions of an antenna device provided in an embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram showing the position of the antenna device provided in an embodiment of the present invention in a spatial rectangular coordinate system is shown.

[0020] Figure 4 Shown Figure 3 Schematic diagram of the radiation direction of the antenna device at 2400 MHz.

[0021] Figure 5 Shown Figure 4 Schematic diagram of the H-plane radiation direction of the antenna device at 2400 MHz.

[0022] Figure 6 Shown Figure 4 Schematic diagram of the E1 radiation direction of the antenna device at 2400 MHz.

[0023] Figure 7 Shown Figure 4 Schematic diagram of the E2 radiation direction of the antenna device at 2400 MHz.

[0024] Figure 8 Shown Figure 3 Schematic diagram of the radiation direction of the antenna device at 2450 MHz.

[0025] Figure 9 Shown Figure 8 Schematic diagram of the H-plane radiation direction of the antenna device at 2450MHz.

[0026] Figure 10 Shown Figure 8 Schematic diagram of the E1 radiation direction of the antenna device at 2450 MHz.

[0027] Figure 11 Shown Figure 8 Schematic diagram of the E2 radiation direction of the antenna device at 2450 MHz.

[0028] Figure 12 Shown Figure 3 Schematic diagram of the radiation direction of the antenna device at 2500 MHz.

[0029] Figure 13 Shown Figure 12 Schematic diagram of the H-plane radiation direction of the antenna device at 2500MHz.

[0030] Figure 14 Shown Figure 12Schematic diagram of the E1 radiation direction of the antenna device at 2500 MHz.

[0031] Figure 15 Shown Figure 12 Schematic diagram of the E2 radiation direction of the antenna device at 2500 MHz.

[0032] Figure 16 A schematic structural diagram of a ZigBee module provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0035] ZigBee is a low-power local area network protocol based on the IEEE 802.15.4 standard. It features low power consumption, low cost, low complexity, strong anti-interference capabilities, and large network capacity. It supports a variety of network topologies, including mesh, star, and tree networks. ZigBee uses three different operating frequency bands: 2.4 GHz, 868 MHz, and 433 MHz, with 2.4 GHz being the mainstream operating frequency band.

[0036] In actual research, the inventors of this application have found that the operating frequency, efficiency, and antenna gain of the antenna radiation can be effectively adjusted by adjusting the wiring method of the antenna device 10. Therefore, designing the wiring spacing and length of the antenna device 10 is an important factor in whether the antenna performance can be improved.

[0037] In view of this, the present invention provides an antenna device 10 that can be used in a ZigBee module 20 to generate a 2.4 GHz operating frequency band. The following embodiments primarily illustrate the use of the antenna device 10 in a ZigBee module 20. Other implementations requiring the antenna device 10 can be referenced accordingly.

[0038] See also Figure 1The antenna device 10 includes a feed source 100 and a radiator 200. The feed source 100 can be electrically connected to a radio frequency circuit, so that the feed source 100 can feed a current signal to the radiator 200, so that the radiator 200 operates in a specified frequency band. The performance of the antenna device 10 can be improved by adjusting the position of the feed source 100 and the radiator 200, as well as adjusting the shape of the radiator 200.

[0039] In this embodiment, the overall shape of the feed source 100 and the radiator 200 is roughly arc-shaped, which is conducive to matching the operating frequency band required by the ZigBee module 20, and allows the antenna device 10 to be routed along the edge of the ZigBee module 20, thereby reducing the physical device of the antenna device 10, reducing the space occupied by the antenna device 10, facilitating the reception and transmission of signals, and enabling the antenna device 10 to have a higher antenna gain and better radiation efficiency, thereby improving the performance of the antenna device.

[0040] Please also refer to Figure 1 and Figure 2 The feed source 100 includes a gold-plated layer 101. The gold-plated layer 101 can enhance the conductive characteristics between the feed source 100 and the radiator 200, which is beneficial for better anti-oxidation and not easily corroded by air, and is also beneficial for reducing signal interference and loss. In this embodiment, the gold-plated layer 101 is along the arc (for Figure 1 The radial length of the gold-plated layer 101 (the dashed line with an arrow in the middle) is L1, where L1 ranges from 5.9 to 6.1 mm, for example, L1 can be 6 mm. The width of the gold-plated layer 101 along the arc is L2, where L2 ranges from 2.9 to 3.1 mm, for example, L2 can be 3 mm. This reduces the area of ​​the feed source 100, reducing its occupied space and facilitating the transmission of electrical signals from the feed source 100 to the radiator 200.

[0041] The radiator 200 includes a first radiating portion 210 and a second radiating portion 220. The first radiating portion 210 is connected between the feed source 100 and the second radiating portion 220. For example, the first radiating portion 210 and the second radiating portion 220 can be arranged along an arc, so that the antenna device 10 can be matched and installed on the ZigBee module 20, thereby enabling the antenna device 10 to better match the operating frequency band of the ZigBee module 20 (for example, the 2.4 GHz operating frequency band), thereby improving the performance of the antenna device 10.

[0042] The first radiating portion 210 has a generally concave shape. The first radiating portion 210 has a first gap 201 disposed between the feed source 100 and the second radiating portion 220. This gap 201 facilitates increasing the length of the first radiating portion 210 and reducing the wiring area of ​​the first radiating portion 210, thereby reducing the footprint of the antenna device 10 and lowering the frequency of the antenna device 10, thereby facilitating matching the antenna device 10 with a suitable operating frequency.

[0043] The first radiating portion 210 may be provided with a first protrusion 211 and a second protrusion 212 on the side facing the center of the arc. The first protrusion 211 is connected to the feed 100, and the second protrusion 212 is connected to the second radiating portion 220 and is opposite the first protrusion 211. The first protrusion 211 and the second protrusion 212 are separated to form the aforementioned first gap 201, which helps increase the routing length of the first radiating portion 210 and reduce the wiring area of ​​the first radiating portion 210, thereby reducing the footprint of the antenna device 10 and lowering the frequency of the antenna device 10, thereby facilitating matching the antenna device 10 with a suitable operating frequency. In this embodiment, the spacing between the first protrusion 211 and the second protrusion 212 is L3, where L3 ranges from 2.9 to 3.1 mm, for example, L3 can be 3 mm. This facilitates adjusting the routing of the first radiating portion 210 by the first protrusion 211 and the second protrusion 212, thereby adjusting the footprint of the first radiating portion 210.

[0044] The second radiating portion 220 includes a first sub-radiating portion 221 and a second sub-radiating portion 222 connected to each other. The end of the first sub-radiating portion 221 facing away from the second sub-radiating portion 222 is connected to the first radiating portion 210, so that the first radiating portion 210 and the second radiating portion 220 are arranged along an arc, which is beneficial to the routing of the antenna device 10 in the ZigBee module 20 and makes it easy to match the antenna with a suitable operating frequency.

[0045] Furthermore, a second gap 202 is formed between the first radiating portion 210, the first sub-radiating portion 221, and the second sub-radiating portion 222. The second gap 202 and the first gap 201 are located on opposite sides of the radiator 200, and the second gap 202 is located on the side of the radiator 200 that is away from the center of the arc. Thus, the presence of the first gap 201 and the second gap 202 contributes to the area of ​​the radiator 200, increases the length of the routing, and reduces the frequency, thereby reducing the space occupied by the antenna device 10 and improving the gain of the antenna device 10.

[0046] The first sub-radiating portion 221 is arranged in an arc shape, which facilitates the arrangement of the first radiating portion 210 and the second radiating portion 220 along the arc, thereby arranging the feed source 100 and the radiator 200 along the arc. In this embodiment, the wiring width of the first sub-radiating portion 221 is L4, where L4 ranges from 1.4 to 1.6 mm, for example, L4 can be 1.5 mm. This facilitates matching the antenna device 10 to the appropriate frequency, improving the efficiency and gain of the antenna device 10.

[0047] The second radiating portion 220 includes a first radiating segment 222a. One end of the first radiating segment 222a is connected to the end of the first sub-radiating portion 221 away from the first radiating portion 210, and the other end of the first radiating segment 222a extends away from the first sub-radiating portion 221. The wiring width of the first radiating segment 222a along the arc is L5, where L5 ranges from 0.9 to 1.1 mm, for example, L5 can be 1 mm. The wiring length of the first radiating segment 222a along the radial direction of the arc is L6, where L6 ranges from 1.9 to 2.1 mm, for example, L6 can be 2 mm. This helps the antenna device 10 match the appropriate frequency and improves the efficiency and gain of the antenna device 10.

[0048] The second radiating portion 220 also includes a second radiating segment 222b, which is connected to the end of the first radiating segment 222a away from the first sub-radiating portion 221. The wiring width of the second radiating segment 222b along the arc is greater than the wiring width of the first radiating segment 222a along the arc. The wiring width of the second radiating segment 222b along the arc is L7, where L7 has a value range of 1.9 to 2.1 mm, for example, L7 can be 2 mm. The wiring length of the second radiating segment 222b along the radial direction of the arc is L8, where L8 has a value range of 2.9 to 3.1 mm, for example, L8 can be 3 mm. This helps the antenna device 10 match the appropriate frequency and improves the efficiency and gain of the antenna device 10.

[0049] Please refer to Table 1. According to the antenna device 10 of the above embodiment, the gain and efficiency corresponding to different frequencies in actual tests are shown in Table 1.

[0050] Table 1

[0051]

[0052] The test data in Table 1 shows that in the 2400 to 2500 GHz frequency band, the gain is between 3.0 dB and 3.5 dB, and the radiation efficiency is between 62.14% and 64.15%. Therefore, the radiation efficiency of the antenna device 10 in this embodiment of the present application is greater than 62% when transmitting and receiving in the 2.4 GHz frequency band, indicating that the gain and radiation efficiency of the antenna device 10 are significantly higher.

[0053] Please refer to Table 2, which shows the frequencies and standing wave ratio values ​​of the antenna device 10 of the above embodiment at multiple measurement points obtained through network analyzer testing.

[0054] Table 2

[0055] Frequency (MHZ) 2400 2500 Standing Wave Ratio 1.46 1.31

[0056] Currently, most board-mounted antenna devices 10 used in 2.4 GHz have a standing wave ratio (SWR) value in the range of 1.5 to 1.6. Therefore, the antenna device 10 according to the embodiment of the present application has the advantage of a low SWR value.

[0057] See also Figure 3 , Figure 3 A schematic diagram of the position of a line device provided by an embodiment of the present application in a spatial rectangular coordinate system is shown. In the spatial rectangular coordinate system O-xyz, the antenna device 10 is located on the xOz coordinate plane, and the origin of the coordinate axis is roughly located in the middle of the antenna device 10, which is conducive to the detection of the antenna device.

[0058] See also Figures 4 to 7 , Figure 4 The figure shows the radiation pattern of the antenna device 10 provided by the embodiment of the present application at 2400MHz in a spatial rectangular coordinate system. The center point of the figure represents the position of the antenna. The farther away from the center point, the greater the gain. The darker the color, the greater the gain of the antenna. Figure 5 is the radiation pattern of the H plane (the H plane is the plane where the magnetic field and the maximum radiation direction are located), Figure 6 is the radiation pattern of the E1 plane (the E plane is the plane with the maximum radiation direction and the electric field), Figure 7 It is the radiation pattern of the E2 plane (the E plane is the plane with the maximum radiation direction and the electric field). Figures 4 to 7 The radiation patterns shown all extend in a certain direction and have a high gain. That is to say, in the plane where the antenna device 10 is located and in the plane perpendicular to the antenna device 10, the gain and efficiency of the antenna device 10 are high, and directional radiation can be achieved. Therefore, the position of the antenna device 10 can be reasonably set according to actual needs to improve practicality.

[0059] See also Figures 8 to 11 , Figure 8 The figure shows the radiation pattern of the antenna device 10 provided by the embodiment of the present application at 2450MHz in a spatial rectangular coordinate system. The center point of the figure represents the position of the antenna. The farther away from the center point, the greater the gain. The darker the color, the greater the gain of the antenna. Figure 9 is the radiation pattern of the H plane (the H plane is the plane where the magnetic field and the maximum radiation direction are located), Figure 10is the radiation pattern of the E1 plane (the E plane is the plane with the maximum radiation direction and the electric field), Figure 11 It is the radiation pattern of the E2 plane (the E plane is the plane with the maximum radiation direction and the electric field). Figures 9 to 11 The radiation patterns shown all extend in a certain direction and have a high gain. That is to say, in the plane where the antenna device 10 is located and in the plane perpendicular to the antenna device 10, the gain and efficiency of the antenna device 10 are high, and directional radiation can be achieved. Therefore, the position of the antenna device 10 can be reasonably set according to actual needs to improve practicality.

[0060] See also Figures 12 to 15 , Figure 12 The figure shows the radiation pattern of the antenna device 10 provided by the embodiment of the present application at 2500MHz in a spatial rectangular coordinate system. The center point of the figure represents the position of the antenna. The farther away from the center point, the greater the gain. The darker the color, the greater the gain of the antenna. Figure 13 is the radiation pattern of the H plane (the H plane is the plane where the magnetic field and the maximum radiation direction are located), Figure 14 is the radiation pattern of the E1 plane (the E plane is the plane with the maximum radiation direction and the electric field), Figure 15 It is the radiation pattern of the E2 plane (the E plane is the plane with the maximum radiation direction and the electric field). Figures 13 to 15 The radiation patterns shown all extend in a certain direction and have a high gain. That is to say, in the plane where the antenna device 10 is located and in the plane perpendicular to the antenna device 10, the gain and efficiency of the antenna device 10 are high, and directional radiation can be achieved. The position of the antenna device 10 can be reasonably set according to actual needs.

[0061] See also Figure 16 The present invention also provides a ZigBee module 20, which includes a circuit board 300 and the antenna device 10 described in the above embodiment. The specific structure of the antenna device 10 is similar to that described in the above embodiment. The ZigBee module 20 can be used, for example, in a gateway device. Because the ZigBee module 20 utilizes all the technical solutions of all the above embodiments, it also possesses all the beneficial effects of the technical solutions of the above embodiments of the antenna device 10, and therefore will not be further elaborated here.

[0062] In some embodiments, the circuit board 300 is provided with a first positioning hole 301, the antenna device 10 is arranged on the circuit board 300, and the first radiating portion 210 is provided with a second positioning hole 302. The second positioning hole 302 is coaxially arranged with the first positioning hole 301, which is conducive to positioning the ZigBee module 20 and further facilitates the installation of the ZigBee module 20.

[0063] In this disclosure, unless otherwise specified or limited, terms such as "mounted" and "connected" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, integral connections, or transmission connections; they can be direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on the specific circumstances.

[0064] In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as a specific reference or special structure. The description of the term "some embodiments" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In the present invention, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present invention and the features of the different embodiments or examples, unless they are contradictory.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. An antenna device, characterized in that: include: Feed; as well as A radiator, the radiator comprising a first radiating portion and a second radiating portion, the first radiating portion being connected to the feed, the first radiating portion having a first gap, the second radiating portion being connected to the first radiating portion, and the second radiating portion and the first radiating portion being arranged along an arc, the second radiating portion comprising a first sub-radiating portion and a second sub-radiating portion connected to each other, an end of the first sub-radiating portion facing away from the second sub-radiating portion being connected to the first radiating portion, a second gap being formed between the first radiating portion, the first sub-radiating portion, and the second sub-radiating portion, the second gap being located on opposite sides of the radiator from the first gap, and the second gap being located on a side of the radiator facing away from the center of the arc; The first radiating portion is provided with a first convex portion and a second convex portion on one side toward the center of the arc, the first convex portion is connected to the feed source, the second convex portion is connected to the first sub-radiating portion, and forms the first gap opposite to the first convex portion; the second gap spacing is larger than the first gap spacing, and the first sub-radiating portion is arc-shaped; The second sub-radiating portion includes a first radiating segment and a second radiating segment, one end of the first radiating segment is connected to an end of the first sub-radiating portion away from the first radiating portion, and the other end of the first radiating segment is connected to the second radiating segment, and the wiring width of the second radiating segment along the direction of the arc is greater than the wiring width of the first radiating segment along the direction of the arc; the wiring width of the first sub-radiating portion is greater than the wiring width of the first radiating segment, and smaller than the wiring width of the second radiating segment.

2. The antenna device according to claim 1, wherein The distance between the first convex portion and the second convex portion is 2.9-3.1 mm.

3. The antenna device according to claim 1, wherein The wiring width of the first sub-radiating portion is 1.4-1.6 mm.

4. The antenna device according to claim 1, wherein The wiring width of the first radiation section along the direction of the arc is 0.9-1.1 mm, and the wiring width of the second radiation section along the direction of the arc is 1.9-2.1 mm.

5. The antenna device according to claim 4, wherein: The wiring length of the first radiation section along the radial direction of the arc is 1.9-2.1 mm, and the wiring length of the second radiation section along the radial direction of the arc is 2.9-3.1 mm.

6. The antenna device according to claim 1, wherein The feed source, the first radiating portion, and the second radiating portion are arranged in sequence along the arc.

7. The antenna device according to claim 6, wherein: The feed source includes a gold-plated layer, the length of the gold-plated layer along the radial direction of the arc is 5.9-6.1 mm, and the width of the gold-plated layer along the direction of the arc is 2.9-3.1 mm.

8. A ZigBee module, characterized in that: include: A circuit board, wherein the circuit board is provided with a first positioning hole; The antenna device according to any one of claims 1 to 7, wherein the antenna device is arranged on the circuit board, the first radiating portion is provided with a second positioning hole, and the second positioning hole is coaxially arranged with the first positioning hole.

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