Full-fabric three-frequency-band three-mode common-caliber antenna applied to wearable field

Abstract

The invention relates to a full-fabric three-frequency-band three-mode common-caliber antenna applied to the wearable field. The full-fabric three-frequency-band three-mode common-caliber antenna comprises an NFC antenna (3), a body surface working mode antenna (4) and an in-vitro working mode antenna (5) on the upper layer, a fabric substrate (1) on the middle layer and a metal ground (2) made of conductive cloth on the bottom layer. An outer metal via hole pair (6) and an inner metal via hole pair (7) are arranged in the fabric substrate (1), the metal ground (2) is formed by a metal ring, an annular metal wall (8) is arranged between the metal ground (2) and the body surface working mode antenna (4), the annular metal wall (8) is positioned in the fabric substrate (1), and the antenna with the same caliber integrates antennas with three different working modes at the same caliber, so that the antenna with the same caliber can be used as a common-caliber antenna. Meanwhile, the single-layer, flexible, breathable and other characteristics are achieved, and an effective solution is provided for highly-integrated wearable equipment in the future.

Description

Technical Field

[0001] The present invention relates to the field of wearables, and in particular to a multi-band and multi-mode co-aperture antenna, which is suitable for a highly integrated wearable wireless communication system that needs to realize multi-band and multiple radiation modes simultaneously. Background Art

[0002] With the rapid development of wireless communication technology and the widespread popularity of smart wearable devices, wearable devices have gradually become one of the important communication terminals in the Internet of Things (IoT). These devices need to achieve efficient and stable wireless communication in various complex environments, which puts higher requirements on the design of the antenna system. The antennas in traditional wearable devices usually have single-band or single-mode communication capabilities, which are difficult to meet the needs of multi-band and multi-mode wireless communication. Existing designs often require the use of multiple independent antenna modules when implementing multi-band communications, which not only increases the size and weight of the device, but also causes interference problems between antennas, affecting communication performance.

[0003] As a new type of antenna design, the co-aperture antenna can achieve multi-band and multi-mode signal transmission in the same aperture and structure, and has the advantages of high integration, lightweight and high performance. This design can significantly reduce the size of the antenna and improve the reliability and communication efficiency of the system. Therefore, the co-aperture antenna with multi-band and multi-mode characteristics shows broad application prospects in highly integrated and compact wearable devices. Summary of the invention

[0004] Technical problem: In order to overcome the shortcomings of the prior art, the present invention proposes a three-band three-mode all-fabric common-aperture antenna for wearable applications. The common-aperture antenna can realize three frequency bands on the same aperture surface, corresponding to three modes. At the same time, the antenna is composed of a full-fabric substrate and a conductive cloth, which not only ensures good electromagnetic performance of the antenna, but also has wearable characteristics such as flexibility and breathability. The invention provides an effective solution for current highly integrated and compact wearable devices.

[0005] Technical solution: To solve the above technical problems, the present invention discloses a full-fabric three-band three-mode common-aperture antenna applied to the wearable field, which has a three-layer structure, including three antennas on the upper layer, a fabric substrate in the middle layer, and a metal ground made of conductive cloth on the bottom layer; the three antennas on the upper layer include an NFC antenna, an antenna in a surface working mode, and an antenna in an external working mode; the fabric substrate has two pairs of metal vias, namely an outer metal via pair and an inner metal via pair, the outer metal via pairs are respectively feeding probes of the antenna in the surface working mode and the antenna in the external working mode, and the inner metal via pair are respectively connected to the ends of the coil of the NFC antenna; the metal ground is composed of a metal ring, and an annular metal wall is provided between the metal ground and the antenna in the surface working mode, and the annular metal wall is located in the fabric substrate.

[0006] The fabric substrate is made of canvas, has good air permeability and can be bent, and is suitable for application scenarios of wearable devices.

[0007] The metal ground is composed of a metal ring, and the hollow area in the middle can reduce the impact on the NFC antenna; in order to facilitate the connection of the SMA connector when testing the surface working mode antenna and the external working mode antenna, two circular holes corresponding to the center positions of the external metal vias are also provided on the metal ring of the metal ground.

[0008] The NFC antenna is a coil antenna, located in the middle of the antenna in the body surface working mode, operates at 13.56 MHz, and operates in the near field mode.

[0009] The two ends of the coil of the NFC antenna are on the same layer, and the inner and outer ends of the NFC antenna are respectively connected to the two holes of the inner metal via pair, and then connected through a short section of metal wire in the middle of the metal ground.

[0010] The body surface working mode antenna is a C-shaped notched ring, which works in the 2.42-2.47 GHz frequency band. The antenna works in the far field mode, has the characteristic of omnidirectional radiation, and is used for communication between body surface sensors.

[0011] The in vitro working mode antenna is located at the gap of the C-shaped notched ring in the surface working mode antenna, and operates in the 5.69-5.97GHz frequency band. The antenna operates in the far-field mode and has directional radiation characteristics, similar to traditional microstrip antennas, and is used for communication between surface sensors and nodes in the environment.

[0012] The external metal via pair is a feeding probe of the antenna in the body surface working mode and the antenna in the body external working mode, and is used for feeding the antenna.

[0013] The inner metal vias connect the ends of the NFC antenna coil and are used to connect the two ends of the coil to the back-end circuit, wherein a portion of the line segments passes through the bottom metal layer.

[0014] The annular metal wall is made of metal wire sewing, connecting the metal ground of the bottom layer and the surface working mode antenna of the upper layer to form a semi-closed cavity to stimulate the TM01 mode. The annular metal wall is not connected to the external working mode antenna so that the external working mode antenna can stimulate TM10.

[0015] Beneficial effects: The present invention provides a compact three-frequency three-mode common aperture antenna, which is composed of three different antennas on one aperture surface, realizing three frequencies and three modes. At the same time, the antenna is composed of a full fabric substrate and conductive cloth, which not only ensures good electromagnetic performance of the antenna, but also has wearable characteristics such as flexibility and breathability. The invention provides an effective solution for highly integrated and compact wearable devices.

[0016] Compared with the existing wearable antenna, the present invention has the following outstanding features: The present invention has a more compact size, has three frequency bands and three modes in the same aperture, and simultaneously realizes a 13.56MHz near-field NFC antenna, a 2.45GHz omnidirectional body surface mode antenna, and a 5.8GHz directional body surface mode antenna.

[0017] The antenna is made of a full fabric base, conductive cloth and conductive thread sewing, so that the antenna not only maintains good electromagnetic performance, but also has the characteristics of breathability and flexibility, providing a good solution for highly integrated and compact wearable devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 It is a top view of the present invention.

[0020] Figure 3 It is a front view of the present invention.

[0021] Figure 4 It is a bottom view of the present invention.

[0022] Figure 5 are the near-field antenna simulation parameters of the present invention.

[0023] Figure 6 is the S parameter of the far-field antenna of the present invention.

[0024] Figure 7 This is the far-field antenna radiation pattern of the present invention.

[0025] The figure includes: fabric substrate 1, metal ground 2, circular hole 2.1, metal wire 2.2, NFC antenna 3, surface working mode antenna 4, external working mode antenna 5, external metal via pair 6, internal metal via pair 7, and annular metal wall 8. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] like Figure 1 , 2, 3 and 4, a three-band three-mode co-aperture antenna for all-fabric wearable devices, the co-aperture antenna has a three-layer structure, including three antennas on the upper layer, a fabric substrate 1 on the middle layer, and a metal ground 2 made of conductive cloth on the bottom layer; the three antennas on the upper layer include an NFC antenna 3, a surface working mode antenna 4 and an external working mode antenna 5; the fabric substrate 1 has two metal via pairs, namely an outer metal via pair 6 and an inner metal via pair 7, the outer metal via pair 6 is respectively a feeding probe of the surface working mode antenna 4 and the external working mode antenna 5, the inner metal via pair 7 is respectively connected to the coil head and tail of the NFC antenna 3; the metal ground 2 is composed of a metal ring, and the hollow area in the middle can reduce the impact on the NFC antenna; in order to facilitate the connection of the SMA connector when testing the surface working mode antenna 4 and the external working mode antenna 5, the metal ring of the metal ground 2 is also provided with two circular holes 2.1 corresponding to the center position of the outer metal via pair 6; an annular metal wall 8 is provided between the metal ground 2 and the surface working mode antenna 4, and the annular metal wall 8 is located in the fabric substrate 1; as shown Figure 1 As shown. The common aperture antenna can work at three frequencies, 13.56MHz, 2.45GHz and 5.8GHz, corresponding to three modes. Among them, NFC antenna 3 works in near field mode. It is made of an inductor coil and can transfer energy according to the near field induction principle. The top view of the coil antenna is shown in Figure 2 As shown in the middle. For the antenna 4 in the body surface working mode, this antenna works in the far field mode. It is formed by cutting off a corner of the upper part of a circular ring antenna to form a C-shaped quasi-circular ring antenna. The antenna works in the TM01 mode and has an omnidirectional radiation pattern, which is used for communication between body surface sensors. For the antenna 5 working in the body external working mode, it is a deformation of the traditional microstrip antenna, so it has a directional radiation pattern and can be used to communicate with external nodes. The fabric substrate 1 used is made of canvas material. This material not only has good air permeability, but also can be bent, which is very suitable for the application scenarios of wearable devices. The outer metal via pair 6 is the feeding probe of the antenna 4 in the body surface working mode and the antenna 5 in the body external working mode, and the inner metal via pair 7 is used to connect the NFC antenna end to end. The metal ground 2 is composed of a metal ring, and the hollow area in the middle can reduce the impact on the NFC antenna. In order to put the two ends of the NFC coil antenna on the same layer, the inner and outer ends of the NFC antenna are respectively connected to the two holes of the inner metal via pair 7, and a small section of metal wire 2.2 in the middle of the metal ground 2 is passed (as shown in FIG. Figure 4 The NFC coil antenna is finally located at both ends of the upper layer, which facilitates the connection of the NFC chip. There is a ring-shaped metal wall 8 sewn by metal conductive wire between the metal ground 2 made of conductive cloth and the body surface working mode antenna 4, as shown in the middle. Figure 3 As shown, it is used to stimulate the TM01 mode in the 2.45 GHz frequency band.

[0028] The fabric base is made of canvas, which not only has good air permeability but is also bendable and can be well combined with wearable applications.

[0029] The NFC antenna operates at 13.56 MHz, works in near field mode, and utilizes the inductance effect to transmit energy and information.

[0030] The body surface working mode antenna operates in the 2.42-2.47 GHz frequency band. The antenna operates in the far field mode, has the characteristic of omnidirectional radiation, and is used for communication between body surface sensors.

[0031] The in vitro working mode antenna operates in the 5.69-5.97 GHz frequency band. The antenna operates in a far-field mode and has a directional radiation characteristic, similar to a traditional microstrip antenna, and is used for communication between a body surface sensor and a node in the environment.

[0032] The annular metal wall is sewn with metal wires, connected to the metal ground and the upper surface working mode antenna to form a closed cavity, stimulate the TM01 mode, and realize an omnidirectional radiation mode.

[0033] In order to explain the design process of each structural parameter, the total size of the antenna is 50mm. 50mm 1.28mm, the antenna is designed on a single-layer canvas substrate with a dielectric constant of 1.65 and a loss tangent of 0.013. Tungsten copper nickel alloy and polyester fiber are the basic components of conductive fabrics. They not only have high conductivity, but also have the inherent advantages of fabrics, including excellent wearing comfort. The NFC antenna is composed of a coil. In order to combine with the commercial NFC chip NT3H1101, the inductance value of the coil needs to be designed at 2.75uH. Using the existing coil design software and HFSS, the final designed coil width is 0.55mm, the line spacing is 0.3mm, and there are 12 turns in total. The imaginary part of the coil and the simulation results of the inductance value are as follows Figure 5As shown. For the surface working mode antenna working at a frequency of 2.45GHz, it is a C-shaped quasi-circular ring antenna formed by removing an angle from a circular ring antenna. The inner and outer radii of the quasi-circular ring antenna are 18mm and 37.2mm respectively, and the angle of removal is 70°. The inside of the surface working mode antenna is connected to the metal ground with a circular metal wall. This semi-enclosed cavity can excite the TM01 mode and finally achieve an omnidirectional radiation characteristic. A circle with a radius of 18mm is hollowed out in the middle of the metal ground. This can reduce the impact of the metal ground on the NFC antenna without affecting the electromagnetic performance of the surface mode antenna. For the 5.8GHz in vitro working mode antenna, it is designed in the vacant position of the 2.45GHz quasi-circular ring antenna, so that the 5.8GHz in vitro working mode can be achieved while basically not changing the overall structure of the antenna.

[0034] Finally, the simulated S parameters of the two far-field antennas are as follows: Figure 6 As shown, from Figure 6 It can be seen that the antenna in the surface working mode achieves a bandwidth of 50MHz at 2.42-2.47GHz, and the antenna in the external working mode achieves a bandwidth of 270MHz at 5.69-5.97GHz. The two antennas achieve -20 and -19dB isolation in the two frequency bands respectively. For the far-field radiation patterns of the two antennas, Figure 7 As shown in the figure, it can be seen that the antenna in the surface working mode realizes an omnidirectional radiation characteristic, while the antenna in the external working mode realizes a directional radiation characteristic. The simulation results verify the feasibility of the two antennas in their respective modes.

[0035] The simulation software is selected such as HFSS of Ansoft, Microwave Studio CST of CST and other high frequency simulation software. The above curves are obtained under given conditions, and similar curves can be obtained by changing the structural parameters.

[0036] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A fully fabric three-band three-mode common aperture antenna for wearable applications, characterized by: The common aperture antenna has a three-layer structure, comprising three types of antennas on an upper layer, a fabric substrate (1) on an intermediate layer, and a metal ground (2) made of conductive fabric on a bottom layer; the three types of antennas on the upper layer include an NFC antenna (3), an antenna in a body surface working mode (4), and an antenna in an external body working mode (5); the fabric substrate (1) has two metal via pairs, namely an outer metal via pair (6) and an inner metal via pair (7); the outer metal via pair (6) is a feeding probe of the antenna in a body surface working mode (4) and the antenna in an external body working mode (5), respectively, and the inner metal via pair (7) is connected to the ends of the coil of the NFC antenna (3); the metal ground (2) is composed of a metal ring; an annular metal wall (8) is provided between the metal ground (2) and the antenna in a body surface working mode (4); the annular metal wall (8) is located in the fabric substrate (1).

2. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 1, characterized in that: The fabric base (1) is made of canvas and should have good air permeability and be bendable, so as to be suitable for application scenarios of wearable devices.

3. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 1, characterized in that: The metal ground (2) is composed of a metal ring, and the hollowed-out area in the middle can reduce the impact on the NFC antenna; in order to facilitate the SMA connector connection when testing the surface working mode antenna (4) and the external working mode antenna (5), two circular holes (2.1) corresponding to the center position of the external metal via hole pair (6) are provided on the metal ring of the metal ground (2).

4. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 1, characterized in that: The NFC antenna (3) is a coil antenna, located in the middle of the body surface working mode antenna (4), operates at 13.56 MHz, and operates in a near field mode.

5. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 4, characterized in that: The two ends of the coil of the NFC antenna (3) are located in the same layer, and the inner and outer ends of the NFC antenna (3) are respectively connected to the two holes of the inner metal via hole pair (7), and then connected through a short section of metal wire (2.2) in the middle of the metal ground (2).

6. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 1, characterized in that: The body surface working mode antenna (4) is a C-shaped notched ring, which works in the 2.42-2.47 GHz frequency band. The antenna works in the far field mode and has the characteristic of omnidirectional radiation, and is used for communication between body surface sensors.

7. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 1 or 6, characterized in that: The external working mode antenna (5) is located at the notch of the C-shaped notched ring in the surface working mode antenna (4), and operates in the 5.69-5.97 GHz frequency band. The antenna operates in a far-field mode and has the characteristic of directional radiation, and is used for communication between surface sensors and nodes in the environment.

8. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 1, characterized in that: The external metal via pair (6) is a feeding probe of the antenna (4) in the body surface working mode and the antenna (5) in the body external working mode, and is used for feeding the antenna.

9. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 1, characterized in that: The inner metal via pair (7) connects the ends of the NFC antenna (3) coil and is used to connect the two ends of the coil to the back-end circuit, wherein a portion of the line segment passes through the bottom metal layer (2).

10. The all-woven three-band three-mode common aperture antenna for wearable applications according to claim 1, characterized in that: The annular metal wall (8) is made by sewing metal wires, connecting the metal ground (2) at the bottom layer and the body surface working mode antenna (4) at the top layer, forming a semi-closed cavity, and exciting the TM01 mode. The annular metal wall (8) is not connected to the body surface working mode antenna (5), so that the body surface working mode antenna (5) can excite TM10.

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