A fully fabric three-band three-mode co-aperture antenna applied to the wearable field

Abstract

The present invention is a full-fabric triple-band triple-mode co-aperture antenna applied to the wearable field, which includes an NFC antenna (3), a body surface working mode antenna (4) and an off-body working mode antenna (5) on the upper layer, a fabric substrate (1) in the middle layer, and a metal ground (2) made of conductive cloth at the bottom layer; an outer metal via pair (6) and an inner metal via pair (7) are provided in the fabric substrate (1), the metal ground (2) is composed of metal rings, and an annular metal wall (8) is provided between the metal ground (2) and the body surface working mode antenna (4), and the annular metal wall (8) is located in the fabric substrate (1). This co-aperture antenna integrates antennas with three different working modes in the same aperture, and at the same time has the characteristics of single-layer, flexible, breathable, etc., providing an effective solution for future highly integrated wearable devices.

Description

Technical Field

[0001] The present invention relates to the field of wearables, and particularly to a co-aperture antenna with multiple frequency bands and multiple modes, which is applicable to a wearable wireless communication system with high integration requirements that needs to simultaneously implement multiple frequency bands and multiple radiation modes. Background Art

[0002] With the rapid development of wireless communication technology and the wide popularization 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, thus posing higher requirements for the design of antenna systems. The antennas in traditional wearable devices usually have the communication ability of a single frequency band or a single mode, and it is difficult to meet the wireless communication requirements of multiple frequency bands and multiple modes. Existing designs often need to use multiple independent antenna modules when implementing multi-band communication, which not only increases the volume 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 signal transmission of multiple frequency bands and multiple modes in the same aperture and structure, and has the advantages of high integration, light weight 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 the characteristics of multiple frequency bands and multiple modes shows broad application prospects in highly integrated and compact wearable devices. Summary of the Invention

[0004] Technical Problem: In order to overcome the deficiencies in the prior art, the present invention proposes a fully fabric three-band three-mode co-aperture antenna applied to the field of wearables. This co-aperture antenna can achieve three frequency bands on the same aperture plane, corresponding to three modes. At the same time, the antenna is composed of a fully 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 current highly integrated and compact wearable devices.

[0005] Technical Solution: To solve the above technical problem, a fully fabric three-band three-mode co-aperture antenna applied to the field of wearables according to the present invention has a three-layer structure, including three antennas in the upper layer, a fabric substrate in the middle layer, and a metal ground made of conductive cloth at the bottom layer; the three antennas in the upper layer include an NFC antenna, a body surface working mode antenna, and an off-body working mode antenna; there are two pairs of metal vias in the fabric substrate, namely an outer metal via pair and an inner metal via pair. The outer metal via pair are respectively the feeding probes of the body surface working mode antenna and the off-body working mode antenna, and the inner metal via pair are respectively connected to the head and tail of the coil of the NFC antenna; the metal ground is composed of a metal ring, and there is an annular metal wall between the metal ground and the body surface working mode antenna, and this annular metal wall is located in the fabric substrate.

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

[0007] The metal ground described above is composed of metal rings, and the hollowed-out area in the middle can reduce the influence on the NFC antenna; in order to facilitate the connection of the SMA connector during the test of the body surface working mode antenna and the off-body working mode antenna, two circular holes corresponding to the center positions of the outer metal vias are also provided on the metal rings of the metal ground.

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

[0009] The two ends of the coil of the NFC antenna described above are 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, and then connected through a small section of metal wire in the middle of the metal ground.

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

[0011] The off-body working mode antenna described above is located at the notch of the C-shaped ring with a notch in the body surface working mode antenna, operates in the frequency band of 5.69 - 5.97 GHz. This antenna operates in the far field mode and has the characteristic of directional radiation, similar to a traditional microstrip antenna, and is used for communication between body surface sensors and nodes in the environment.

[0012] The outer metal via pair described above is the feeding probe of the body surface working mode antenna and the off-body working mode antenna, and is used for feeding the antenna.

[0013] The inner metal via pair described above connects the head and tail of the NFC antenna coil, and is used for connecting the two ends of the coil to the backend circuit, and a part of the line passes through the bottom metal ground layer.

[0014] The annular metal wall described above is sewn with metal wires, connects the metal ground at the bottom layer and the body surface working mode antenna at the upper layer, forms a semi-closed cavity, and excites the TM01 mode. The annular metal wall is not connected to the off-body working mode antenna, so that the off-body working mode antenna can excite the TM10.

[0015] Beneficial effects: The present invention provides a compact triple - band and triple - mode co - aperture antenna, which consists of three different antennas on one aperture plane, 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 the characteristics of flexibility, breathability, etc., making it wearable. The invention provides an effective solution for high - integration and compact wearable devices.

[0016] The present invention has the following outstanding characteristics compared with the existing wearable antennas:

[0017] The present invention has a more compact size, with three frequency bands and three modes in the same aperture, simultaneously realizing a near - field NFC antenna at 13.56 MHz, an omnidirectional body - surface mode antenna at 2.45 GHz, and a directional off - body mode antenna at 5.8 GHz.

[0018] The antenna is composed of a full - fabric substrate, conductive cloth and conductive wires sewn together, which not only maintains good electromagnetic performance, but also has the characteristics of breathability and flexibility, providing a good solution for high - integration and compact wearable devices. Description of the drawings

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 It is a top view of the present invention.

[0021] Figure 3 It is a front view of the present invention.

[0022] Figure 4 It is a bottom view of the present invention.

[0023] Figure 5 It is the simulation parameters of the near - field antenna of the present invention.

[0024] Figure 6 It is the S - parameter of the far - field antenna of the present invention.

[0025] Figure 7 It is the radiation pattern of the far - field antenna of the present invention.

[0026] In the figure: fabric substrate 1, metal ground 2, round hole 2.1, metal wire 2.2, NFC antenna 3, body - surface working mode antenna 4, off - body working mode antenna 5, outer metal via pair 6, inner metal via pair 7, annular metal wall 8. Detailed implementation manners

[0027] The present invention will be further described below with reference to the drawings.

[0028] Such as Figure 1 、 2, as shown in Figures 3 and 4, a triple-band and triple-mode common-aperture antenna made of all-fabric for wearable devices. This common-aperture antenna has a three-layer structure, including three antennas on the upper layer, a fabric substrate 1 in the middle layer, and a metal ground 2 made of conductive cloth at the bottom layer; the three antennas on the upper layer include an NFC antenna 3, a body-surface working mode antenna 4, and an off-body working mode antenna 5; there are two pairs of metal vias in the fabric substrate 1, namely an outer metal via pair 6 and an inner metal via pair 7. The outer metal via pair 6 are respectively the feeding probes of the body-surface working mode antenna 4 and the off-body working mode antenna 5, and the inner metal via pair 7 are respectively connected to the head and tail of the coil of the NFC antenna 3; the metal ground 2 is composed of a metal ring, and the hollowed-out area in the middle can reduce the influence on the NFC antenna; in order to facilitate the connection of the SMA connector during the test of the body-surface working mode antenna 4 and the off-body working mode antenna 5, two circular holes 2.1 corresponding to the center positions of the outer metal via pair 6 are also provided on the metal ring of the metal ground 2; there is an annular metal wall 8 between the metal ground 2 and the body-surface working mode antenna 4, and this annular metal wall 8 is located in the fabric substrate 1; as Figure 1 shown. This common-aperture antenna can work at three frequencies of 13.56 MHz, 2.45 GHz, and 5.8 GHz respectively, corresponding to three modes. Among them, the NFC antenna 3 works in the near-field mode. It is made of an inductance coil and can transfer energy according to the principle of near-field induction. The top view of the coil antenna is as Figure 2 shown in the middle. For the body-surface working mode antenna 4, this antenna works in the far-field mode. It is formed by cutting off a corner from the upper part of a circular-ring antenna to form a C-shaped quasi-circular-ring antenna. This antenna works in the TM01 mode and has an omnidirectional radiation pattern, which is used for communication between body-surface sensors. For the off-body working mode antenna 5, it is a deformation of a traditional microstrip antenna, so it has a directional radiation pattern and can be used for communication with external nodes. The used fabric substrate 1 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 scenario of wearable devices. The outer metal via pair 6 are respectively the feeding probes of the body-surface working mode antenna 4 and the off-body working mode antenna 5, and the inner metal via pair 7 are used for connecting the head and tail of the NFC antenna. The metal ground 2 is composed of a metal ring, and the hollowed-out area in the middle can reduce the influence on the NFC antenna. In order to place 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. After passing through a small section of metal wire 2.2 in the middle of the metal ground 2 (as Figure 4 shown in the middle), and then reaching the upper layer, finally, both ends of the NFC coil antenna are in the upper layer area, which is convenient for the connection of the NFC chip. There is an annular metal wall 8 sewn by metal conductive wires between the metal ground 2 made of conductive cloth and the body-surface working mode antenna 4, as Figure 3 shown, which is used to excite the TM01 mode in the 2.45 GHz frequency band.

[0029] The fabric substrate described above is made of canvas, which not only has good air permeability but can also be bent, enabling it to be well combined with wearable applications.

[0030] The NFC antenna described above operates at 13.56 MHz and in the near-field mode, using the inductive effect to transmit energy and information.

[0031] The body surface operating mode antenna described above operates in the frequency band of 2.42 - 2.47 GHz. This antenna operates in the far-field mode and has the characteristic of omnidirectional radiation, which is used for communication between body surface sensors.

[0032] The off-body operating mode antenna described above operates in the frequency band of 5.69 - 5.97 GHz. This antenna operates in the far-field mode and has the characteristic of directional radiation, similar to a traditional microstrip antenna, which is used for communication between body surface sensors and nodes in the environment.

[0033] The circular metal wall described above is sewn with metal wires, connecting the metal ground and the upper-layer body surface operating mode antenna to form a closed cavity, exciting the TM01 mode to achieve an omnidirectional radiation pattern.

[0034] To facilitate the description of the design process of each structural parameter, given the structural parameters, the total size of the antenna is 50 mm 50 mm 1.28 mm. 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 the conductive fabric, which not only have high conductivity but also have the inherent advantages of the fabric, including excellent wearing comfort. For the NFC antenna composed of coils, in order to be combined with the commercial NFC chip NT3H1101, the inductance value of the coil needs to be designed at 2.75 μH. Using existing coil design software and HFSS, the finally designed coil width is 0.55 mm, the line-to-line spacing is 0.3 mm, and there are 12 turns in total. The simulation results of the imaginary part and inductance value of the coil are as Figure 5As shown in the figure. For the body surface operating mode antenna operating at 2.45 GHz, it is formed by removing an angle from a circular loop antenna to form a C-shaped quasi-circular loop antenna. The inner and outer radii of the quasi-circular loop antenna are 18 mm and 37.2 mm respectively, and the removed angle is 70°. The inside of the body surface operating mode antenna is connected to the metal ground by a circular metal wall. This semi-closed cavity can excite the TM01 mode, and finally an omnidirectional radiation characteristic is achieved. A circle with a radius of 18 mm is hollowed out in the middle of the metal ground. This can reduce the influence of the metal ground on the NFC antenna without affecting the electromagnetic performance of the body surface mode antenna. For the 5.8 GHz off-body operating mode antenna, it is designed at the position vacant from the 2.45 GHz quasi-circular loop antenna, so that the overall structure of the antenna can be basically unchanged while realizing the 5.8 GHz off-body operating mode.

[0035] Finally, the simulated S-parameters of the two far-field antennas are as Figure 6 shown. From Figure 6 it can be seen that the body surface operating mode antenna achieves a 50 MHz bandwidth in the range of 2.42 - 2.47 GHz, and the off-body operating mode antenna achieves a 270 MHz bandwidth in the range of 5.69 - 5.97 GHz. The two antennas achieve isolation degrees of -20 dB and -19 dB respectively in the two frequency bands. For the far-field radiation patterns of the two antennas as Figure 7 shown. From the figure, it can be seen that the body surface operating mode antenna achieves an omnidirectional radiation characteristic, and at the same time, the off-body operating mode antenna achieves a directional radiation characteristic. The simulation results verify the feasibility of the two antennas in their respective modes.

[0036] High-frequency simulation software such as HFSS from Ansoft Corporation and Microwave Studio CST from CST Corporation is selected. The curves obtained above are obtained under given conditions. Similar curves can also be obtained by changing the structural parameters.

[0037] The above are only the preferred embodiments of the present invention. It should be noted that: for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope 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) on a bottom layer made of conductive fabric; 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, and an annular metal wall (8) is provided between the metal ground (2) and the antenna in a body surface working mode (4), and the annular metal wall (8) is located in the fabric substrate (1); The surface working mode antenna (4) is a C-shaped notched ring, 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 the NFC antenna (3) is a coil antenna located in the middle of the surface working mode antenna (4).

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) operates at 13.56 MHz and in 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) operates in the 2.42-2.47 GHz frequency band. The antenna operates 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 in vitro working mode antenna (5) 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. It is used for communication between body 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 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).

9. 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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