Double-antenna design method for high-precision positioning

Abstract

The invention discloses a double-antenna design method for high-precision positioning, and belongs to the technical field of high-precision positioning antennas. The radiation unit is used as a radiator, so that the resonant frequency and the radiation characteristic of the antenna are optimized, the radiation unit adopts a winding form, and the physical size and the effective length of the antenna are optimized; meanwhile, the slotting technology is applied, the current distribution and bandwidth of the antenna are optimized, the PCB serves as a reflecting surface, the inner end in the radiation unit is used for grounding and feeding, the resonance characteristic and impedance of the antenna are optimized, the included angle between the two antennas is designed to be 90 degrees, the port isolation degree and the polarization diversity gain are optimized, and therefore the antenna is smaller in size, small in size and high in practicability. In the 2.4 G frequency band, the horizontal radiating surface has good omnidirectivity, the anti-multipath effect is achieved, the occupied area is reduced, meanwhile, the cost is reduced, and the positioning precision is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-precision positioning antennas, and in particular relates to a dual-antenna design method for high-precision positioning. Background Art

[0002] ‌Channel Sounding‌ is a new Bluetooth technology that aims to improve the high-precision positioning and ranging capabilities between Bluetooth devices. It is mainly used in the fields of Internet of Things, smart home, electric vehicles, communications, and asset tracking to meet the needs of these fields for high-precision positioning‌.

[0003] Channel Sounding has the following advantages over traditional RSSI technology and AoA / AoD positioning technology: ‌High Precision‌: Positioning accuracy can reach centimeter level, meeting more high-precision positioning needs.

[0004] ‌Strong anti-interference ability‌: By combining phase measurement and RTT measurement, the anti-interference ability of ranging is improved.

[0005] ‌High security‌: It integrates multiple security mechanisms to effectively prevent attacks such as distance deception.

[0006] During the Channel Sounding test, antennas are needed to send and receive electromagnetic waves, and the high-precision positioning system recommends an antenna path range of 1 to 4. However, the existing single-antenna system has a worse positioning effect than the dual-antenna system due to the multipath effect of electromagnetic wave transmission. The three- and four-antenna systems have disadvantages such as complex algorithms, low antenna isolation, and large occupied area.

[0007] Therefore, the current design method of dual antennas for high-precision positioning has the following problems: it is necessary to comprehensively consider the anti-multipath effect, reduce the footprint and reduce the cost, select appropriate antenna design and layout, and improve positioning accuracy. Summary of the invention

[0008] In view of the problems raised by the above background technology, the purpose of the present invention is to provide a dual-antenna design method for high-precision positioning.

[0009] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows: A dual antenna design method for high-precision positioning, wherein a single antenna comprises a radiating unit, a coaxial feeder and a short-circuit metal sheet, wherein the coaxial feeder and the short-circuit metal sheet are partially connected to the radiating unit, and the design method comprises the following steps: S1: Taking 2.45 GHz as the center frequency, the corresponding free space wavelength is 122 mm according to the formula λ=v / f. The PIFA antenna is a monopole antenna. This type of monopole antenna adopts a quarter-wavelength design, so the total length of the corresponding radiation unit is 30.5 mm. First, adjust the length of the radiation unit in this design to 30 mm. S2: Due to the design requirements of miniaturization, a meandering form is adopted in the design process of the radiation unit, and the radiation unit is bent inward to reduce the aspect ratio of the radiation unit; S3: In order to meet the design requirement of stabilizing the current path balance of a single antenna on a dielectric substrate, a coaxial feed line is arranged at the top of the inner end of the radiation unit, and short-circuit metal sheets are arranged on both sides of the bottom of the inner end of the radiation unit, so that the coaxial feed line and the short-circuit metal sheet at the inner end of the antenna form a stable triangular support structure; S4: Due to the design requirement of increasing the radiation bandwidth, the upper part of the radiating unit after winding is widened, and widening plates are arranged on both sides thereof, thereby increasing the bandwidth of the antenna; S5: Due to the design requirement of impedance matching, a slot is provided at the upper part of the outer end of the radiating element after the meandering, and the depth and width of the slot are reasonably set; S6: the aspect ratio of the radiation unit after the slot design in S5 is adjusted again; S7: A secondary widening and winding design is performed on the upper part of the outer end of the radiating element after the radiating element is bent, so that the antenna can achieve broadband matching at 2.45GHz; S8: To meet the design requirements of antenna isolation and floor space, adjust the antenna spacing and set the angle between the two antennas to 90°.

[0010] It is further defined that in the S2 and S6, the aspect ratio needs to be considered in the design, and the aspect ratio is 0.55 mm. Such a structural design further reduces the footprint of the antenna.

[0011] It is further defined that in S2, according to Richard transformation, the radiation unit part located at the outer end of the coaxial feed line and the short-circuit metal sheet plays the role of equivalent inductance, and this part is designed to be equal in length to the radiation unit part at the inner end after winding. Such a structural design achieves the purpose of miniaturization.

[0012] It is further defined that in said S4, the upper portion of the meandering radiation unit is 8 mm before widening and is 20 mm after the widening plate is provided. Such a structural design further improves the bandwidth of the antenna.

[0013] It is further defined that in said S4, the spacing between the meandering upper portion of the radiation unit and the widening plates on both sides is set to 1.5 mm, and the length of the widening plates is 3.4 mm. Such a structural design makes the overall setting more reasonable.

[0014] It is further defined that in said S5, the bottom of the slot is designed in a rounded structure, and the upper end of the slot is designed in a rectangular structure. Such a structural design facilitates the subsequent matching of the wide band.

[0015] It is further defined that in S5, the depth of the slot is 7.3 mm. Such a structural design satisfies the broadband matching of the subsequent antenna.

[0016] It is further defined that in said S7, both sides of the outer end of the radiation unit are widened inwards, and after widening, the width is 21.5 mm. Such a structural design is convenient for satisfying the design requirements of the antenna.

[0017] It is further defined that, in the S8, the closest end distance between the two antennas is 18.83 mm. Such a structural design enables the two antennas to meet the design requirements of isolation and floor space.

[0018] It is further defined that the structure of the radiation unit between the coaxial feed line and the short-circuit metal sheet is designed in the form of a gradient line. Such a structural design improves the use effect of the antenna.

[0019] The beneficial effects of the present invention are as follows: the present invention optimizes the resonant frequency and radiation characteristics of the antenna by using the radiation unit as a radiator, and the radiation unit adopts a meandering form, which optimizes the physical size and effective length of the antenna; at the same time, the slotting technology is applied to optimize the current distribution and bandwidth of the antenna, and the PCB board is used as a reflection surface, and the inner end of the radiation unit 1 is used for grounding and feeding, which optimizes the resonant characteristics and impedance of the antenna, and the angle between the two antennas is designed to be 90°, which optimizes the port isolation and polarization diversity gain, so that the present invention has a smaller antenna volume, and in the 2.4G frequency band, the horizontal radiation surface has good omnidirectionality, has the advantages of resisting multipath effects, reducing the footprint, reducing costs, and improving positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings; Figure 1 This is a schematic diagram of the axial structure of a high-precision positioning antenna according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the main structure of a high-precision positioning antenna according to an embodiment of the present invention; Figure 3 It is a schematic diagram of the side structure of a high-precision positioning antenna according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the upward structure of a high-precision positioning antenna according to an embodiment of the present invention; Figure 5 This is a design reference diagram of the floor space in the embodiment of the present invention; Figure 6This is a diagram showing the simulation results of the antenna frequency characteristics in an embodiment of the present invention; Figure 7 This is a simulation effect diagram of isolation in an embodiment of the present invention; Figure 8 3D directional diagram of the left antenna at 2.4G in an embodiment of the present invention; Fig. 9 is the xoy plane radiation pattern of the left antenna in the embodiment of the present invention; Fig.10 3D directional diagram of the right antenna at 2.4G in an embodiment of the present invention; Fig.11 is the xoy plane radiation pattern of the right antenna in the embodiment of the present invention; Fig.12 In the embodiment of the present invention Figures 8 to 11 Schematic diagram of the coordinate system; Fig.13 Schematic diagram of the working process of the antenna in an embodiment of the present invention; The main component symbols are described as follows: Radiating unit 1, coaxial feed line 2, short-circuit metal sheet 3, widening plate 4, slot 5. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0022] like Figure 1-4 As shown, a dual antenna design method for high-precision positioning of the present invention, a single antenna includes a radiation unit 1, a coaxial feeder 2 and a short-circuit metal sheet 3, the coaxial feeder 2 and the short-circuit metal sheet 3 are partially connected to the radiation unit 1, and the design method includes the following steps: S1: Taking 2.45 GHz as the center frequency, the corresponding free space wavelength is 122 mm according to the formula λ=v / f. The PIFA antenna is a monopole antenna. This type of monopole antenna adopts a quarter-wavelength design, so the total length of the corresponding radiation unit is 30.5 mm. First, adjust the length of the radiation unit 1 in this design to 30 mm. S2: Due to the design requirement of miniaturization, a meandering form is adopted in the design process of the radiation unit 1, and the radiation unit 1 is meandered inward to reduce the aspect ratio of the radiation unit 1; S3: In order to meet the design requirement of stabilizing the current path balance of a single antenna on a dielectric substrate, a coaxial feed line 2 is arranged on the top of the inner end of the radiation unit 1, and short-circuit metal sheets 3 are arranged on both sides of the bottom of the inner end of the radiation unit 1, so that the coaxial feed line 2 and the short-circuit metal sheets 3 at the inner end of the antenna form a stable triangular support structure; S4: Due to the design requirement of increasing the radiation bandwidth, the upper portion of the radiating unit 1 after winding is widened, and widening plates 4 are arranged on both sides thereof, thereby increasing the bandwidth of the antenna; S5: Due to the design requirement of impedance matching, a slot 5 is provided at the upper part of the outer end of the radiating unit 1 after the meandering, and the depth and width of the slot 5 are reasonably set; S6: the aspect ratio of the radiation unit 1 after the slot 5 is designed in S5 is adjusted again; S7: A secondary widening and winding design is performed on the upper part of the outer end of the radiating element 1 after the winding, so that the antenna can achieve broadband matching at 2.45 GHz; S8: To meet the design requirements of antenna isolation and floor space, adjust the antenna spacing and set the angle between the two antennas to 90°.

[0023] Preferably, in S2 and S6, the aspect ratio needs to be considered in the design, and the aspect ratio is 0.55 mm. Such a structural design further reduces the footprint of the antenna.

[0024] Preferably, in S2, according to Richard transformation, the radiation unit 1 portion located at the outer end of the coaxial feed line 2 and the short-circuit metal sheet 3 plays the role of equivalent inductance, and this portion is designed to be equal in length to the radiation unit portion at the inner end after winding. Such a structural design achieves the purpose of miniaturization.

[0025] Preferably, in S4, the upper portion of the meandering radiation unit 1 is 8 mm before widening, and is 20 mm after the widening plate 4 is provided. Such a structural design further improves the bandwidth of the antenna.

[0026] Preferably, in S4, the spacing between the meandering upper portion of the radiation unit 1 and the widening plates 4 on both sides is set to 1.5 mm, and the length of the widening plates 4 is 3.4 mm. Such a structural design makes the overall setting more reasonable.

[0027] Preferably, in S5, the bottom of the slot 5 is designed to be rounded, and the upper end of the slot 5 is designed to be rectangular. Such a structural design facilitates subsequent broadband matching.

[0028] Preferably, in S5, the depth of the slot 5 is 7.3 mm. Such a structural design satisfies the broadband matching of the subsequent antenna.

[0029] Preferably, in S7, both sides of the outer end of the radiation unit 1 are widened inwards to 21.5 mm after widening. Such a structural design is convenient for meeting the design requirements of the antenna.

[0030] Preferably, in S8, the closest end distance between the dual antennas is 18.83 mm. Such a structural design enables the two antennas to meet the design requirements of isolation and floor space.

[0031] Preferably, the structure of the radiation unit 1 between the coaxial feed line 2 and the short-circuit metal sheet 3 is designed in the form of a gradient line. Such a structural design improves the use effect of the antenna.

[0032] The present invention also has a processed dual-antenna model object and a test result in a microwave darkroom.

[0033] Directivity (simple) diagram obtained from the actual antenna test: like Figure 5 As shown in the figure, this is a schematic diagram of the layout of the left and right antennas on the PCB, with the closest end distance being 18.83 mm.

[0034] like Figure 6 As shown, this figure is the S(1,1) parameter diagram of a single antenna. The S(1,1) parameter is less than -20dBm near 2.45GHz.

[0035] This means that very little signal energy is reflected back from the antenna input port, and most of the signal energy is received or radiated by the antenna.

[0036] like Figure 7 As shown, this figure is the S(2,1) parameter diagram of the two antennas. The S(2,1) parameter is less than -10dBm near 2.45GHz.

[0037] This means that the isolation between the two antennas is high, the antenna mutual coupling is small, and the signal interference is small.

[0038] like Figure 8 As shown in the figure, this is the 3D radiation pattern of the left antenna, which shows some radiation characteristics of the left antenna in the 2.4G frequency band.

[0039] like Fig. 9 As shown, this figure is the xoy radiation pattern of the left antenna, which shows the radiation characteristics of the left antenna in the xoy plane in the 2.4G frequency band.

[0040] like Fig.10 As shown in the figure, this is the 3D radiation pattern of the right antenna, which shows some radiation characteristics of the right antenna in the 2.4G frequency band.

[0041] like Fig.11 As shown, this figure is the xoy radiation pattern of the right antenna, which shows the radiation characteristics of the right antenna in the xoy plane in the 2.4G frequency band.

[0042] like Fig.12 As shown, the figure shows the above Figures 8 to 11 The coordinate system of the test results is the location on the PCB.

[0043] According to the above four figures, it can be concluded that the radiation omnidirectionality of the two antennas is good, and the radiated energy is relatively evenly distributed in all directions in space.

[0044] like Fig.13 As shown, the figure shows the working flow diagram of the antenna.

[0045] The external current signal is received through the antenna's feeding structure, and the external current signal is transmitted to the antenna radiation unit through the coaxial feeding structure, and finally the electromagnetic wave signal is radiated into space through the antenna radiation unit.

[0046] In this embodiment, a single antenna is composed of a radiation unit 1, a coaxial feed line 2 and a short-circuit metal sheet 3. The coaxial feed line 2 and the short-circuit metal sheet 3 are connected by a part of the radiation unit 1. With 2.45 GHz as the center frequency, the corresponding free space wavelength is 122 mm according to the formula λ=v / f. The PIFA antenna is a monopole antenna. This type of monopole antenna usually adopts a quarter-wavelength design. Therefore, the total length of the corresponding radiation unit is 30.5 mm. First, the length of the radiation unit 1 in this design is adjusted to 30 mm. Due to the design requirements of miniaturization, the radiation unit 1 is designed in the process of designing the radiation unit 1. The radiation unit 1 is meandered inward in a meandering manner to reduce the aspect ratio of the radiation unit 1, and its aspect ratio is 0.55 mm. According to the Richard transformation, the portion of the radiation unit 1 located at the outer end of the coaxial feed line 2 and the short-circuit metal sheet 3 plays the role of an equivalent inductor. This portion is designed to be equal in length to the radiation unit portion at the inner end after the meandering, so as to achieve the purpose of miniaturization. In order to meet the design requirements of stabilizing the current path balance of a single antenna on a dielectric substrate, a coaxial feed line 2 is arranged at the top of the inner end of the radiation unit 1, and short-circuit metal sheets 3 are arranged on both sides of the bottom of the inner end of the radiation unit 1, so that the coaxial feed line 2 and the short-circuit metal sheet 3 at the inner end of the antenna form a A stable triangular support structure is formed. Due to the design requirement of increasing the radiation bandwidth, the upper part of the radiation unit 1 after winding is widened, and widening plates 4 are set on both sides thereof, thereby increasing the bandwidth of the antenna. The upper part of the radiation unit 1 after winding is 8mm before widening, and is 20mm after the widening plates 4 are set. The spacing between the upper part of the radiation unit 1 after winding and the widening plates 4 on both sides is set to 1.5mm, and the length of the widening plate 4 is 3.4mm. Due to the design requirement of impedance matching, a slot 5 is set on the upper part of the outer end of the radiation unit 1 after winding, and the depth and width of the slot 5 are reasonably set, and the bottom of the slot 5 is rounded. shaped structure design, the upper end of the slot 5 is rectangular structure design, the depth of the slot 5 is 7.3mm, the aspect ratio of the radiation unit 1 after the slot 5 design in S5 is adjusted again, and its aspect ratio is 0.55mm, and the upper part of the outer end of the radiation unit 1 after winding is secondarily widened and meandered, so that the antenna can achieve broadband matching at 2.45GHz, and the outer ends of the radiation unit 1 are widened inward on both sides, and after widening, it is 21.5mm. In order to meet the design requirements of antenna isolation and floor space, the antenna spacing is adjusted, and the angle between the dual antennas is set to 90°, and the nearest end spacing of the dual antennas is 18.83mm.

[0047] Among them, Fig. 9 and Fig.11 In the Xoy directional diagram, the colored lines represent the directional characteristics at different frequencies when theta = 90°. These colored lines are all theta = 90°.

[0048] The antenna's resonant frequency and radiation characteristics are optimized by using the radiation unit 1 as a radiator. The radiation unit 1 adopts a meandering form to optimize the antenna's physical size and effective length. At the same time, the slotting technology is applied to optimize the antenna's current distribution and bandwidth.

[0049] When a single antenna is installed, the radiation unit 1 is connected to the PCB board through the coaxial feed line 2 and the short-circuit metal sheet 3. The PCB board is used as a reflection surface, and the inner end of the radiation unit 1 is used for grounding and feeding, which optimizes the resonance characteristics and impedance of the antenna. The angle between the two antennas is designed to be 90°, which optimizes the port isolation and polarization diversity gain.

[0050] According to the antenna design of this patent, the input impedance of any single antenna is matched to 50 ohms, the input efficiency is greater than 60%, the input standing wave ratio in the 2.4G frequency band is less than 2, it has a fixed propagation group delay and linear propagation phase, and the maximum gain of the antenna is less than 2dB between different channels. The angle between the two antennas is 90°, and the isolation is greater than 18dB.

[0051] The present invention is a dual-antenna design for Channel Sounding ranging. This patent has good directionality under high isolation to achieve antenna working states in different scenarios, to adapt to Bluetooth technology requirements such as Channel Sounding and RSSI, and to cope with precise positioning application scenarios such as digital keys, smart tags, asset tracking, and location services. At the same time, a single antenna can be flexibly configured to work independently to adapt to the specific working requirements of radio frequency transmission and reception, thereby expanding business space.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A dual-antenna design method for high-precision positioning, characterized in that: A single antenna comprises a radiation unit (1), a coaxial feed line (2) and a short-circuit metal sheet (3), wherein the coaxial feed line (2) and the short-circuit metal sheet (3) are partially connected to the radiation unit (1), and the design method comprises the following steps: S1: Taking 2.45 GHz as the center frequency, the corresponding free space wavelength is 122 mm according to the formula λ=v / f. The PIFA antenna is a monopole antenna. This type of monopole antenna adopts a quarter-wavelength design, so the total length of the corresponding radiation unit is 30.5 mm. First, adjust the length of the radiation unit (1) in this design to 30 mm. S2: Due to the design requirement of miniaturization, a meandering form is adopted in the design process of the radiation unit (1), and the radiation unit (1) is meandered inwards to reduce the aspect ratio of the radiation unit (1); S3: In order to meet the design requirement of stabilizing the current path balance of a single antenna on a dielectric substrate, a coaxial feed line (2) is arranged at the top of the inner end of the radiation unit (1), and short-circuit metal sheets (3) are arranged on both sides of the bottom of the inner end of the radiation unit (1), so that the coaxial feed line (2) and the short-circuit metal sheets (3) at the inner end of the antenna form a stable triangular support structure; S4: Due to the design requirement of increasing the radiation bandwidth, the upper portion of the radiating unit (1) after winding is widened, and widening plates (4) are arranged on both sides thereof, thereby increasing the bandwidth of the antenna; S5: In order to meet the design requirements for impedance matching, a slot (5) is provided at the upper portion of the outer end of the radiating unit (1) after winding, and the depth and width of the slot (5) are reasonably set; S6: the aspect ratio of the radiation unit (1) designed by slotting (5) in S5 is adjusted again; S7: A secondary widening and winding design is performed on the upper portion of the outer end of the radiating element (1) after the radiating element (1) is bent, so that the antenna can achieve broadband matching at 2.45 GHz; S8: To meet the design requirements of antenna isolation and floor space, adjust the antenna spacing and set the angle between the two antennas to 90°.

2. The dual antenna design method for high-precision positioning according to claim 1, characterized in that: In the S2 and S6, the aspect ratio needs to be considered simultaneously in the design, and the aspect ratio is 0.55 mm.

3. The dual antenna design method for high-precision positioning according to claim 2, characterized in that: In S2, according to Richard transformation, the portion of the radiation unit (1) located at the outer end of the coaxial feed line (2) and the short-circuit metal sheet (3) plays the role of an equivalent inductor, and this portion is designed to be equal in length to the radiation unit portion at the inner end after winding.

4. The dual antenna design method for high-precision positioning according to claim 3, characterized in that: In S4, the upper portion of the radiating unit (1) after winding is 8 mm before widening, and is 20 mm after the widening plate (4) is provided.

5. The dual antenna design method for high-precision positioning according to claim 4, characterized in that: In S4, the spacing between the meandering upper portion of the radiation unit (1) and the widening plates (4) on both sides is set to 1.5 mm, and the length of the widening plates (4) is 3.4 mm.

6. The dual antenna design method for high-precision positioning according to claim 5, characterized in that: In S5, the bottom of the slot (5) is designed to be a rounded structure, and the upper end of the slot (5) is designed to be a rectangular structure.

7. The dual antenna design method for high-precision positioning according to claim 6, characterized in that: In the S5, the depth of the groove (5) is 7.3 mm.

8. The dual antenna design method for high-precision positioning according to claim 7, characterized in that: In S7, both sides of the outer end of the radiation unit (1) are widened inwards to 21.5 mm after widening.

9. The dual antenna design method for high-precision positioning according to claim 8, characterized in that: In the S8, the closest distance between the dual antennas is 18.83 mm.

10. The dual antenna design method for high-precision positioning according to claim 9, characterized in that: The structure of the radiation unit (1) between the coaxial feed line (2) and the short-circuit metal sheet (3) is designed in the form of a gradient line.

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