A flexible dual-band and dual-mode common-aperture antenna applied to the wearable field

Abstract

The present invention discloses a flexible dual-band dual-mode common-aperture antenna applied to the wearable field, which includes a body surface working mode antenna (3) and an extracorporeal working mode antenna (4), a flexible substrate (1) in the middle layer, and a metal ground (2) made of a copper film at the bottom layer. The flexible substrate (1) has an outer metal via pair (5) and an inner metal via (6). A metal via (7) distributed in a ring shape is provided between the metal ground (2) and the body surface working mode antenna (3), and the metal via (7) distributed in a ring shape is located in the flexible substrate (1). This common-aperture antenna has a compact structure, integrates antennas of two different working modes in the same aperture, and improves the working bandwidth of its body surface working mode antenna through mode merging, making it more suitable for working on a flexible substrate. This common-aperture antenna provides an effective solution for future highly integrated wearable devices.

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 antennas used in human body area networks (WBANs) have received increasing attention. These devices can be used in various application scenarios such as medical monitoring, personal entertainment activities, sports, military operations, and identification systems. In order to achieve efficient and stable wireless communication in various complex environments, modern wireless communication technology has put forward higher requirements on the design of antenna systems. In order to meet the needs of multi-band and multi-mode wireless communication, existing antenna designs usually use multiple independent antennas when implementing multi-band and multi-mode communications. This not only increases the size and weight of the device, but is also not conducive to the integration of the antenna, nor is it conducive to the bending deformation of the antenna to meet wearable needs.

[0003] The co-aperture antenna design 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 not only significantly reduce the planar size of the antenna, but also usually reduce the profile height and number of layers of the antenna, making the antenna more suitable for wearable fields. 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 flexible dual-band dual-mode co-aperture antenna for use in the wearable field. The co-aperture antenna can realize two frequency bands on the same aperture surface, corresponding to two modes. In addition, the antenna is based on a flexible substrate, has the characteristics of flexibility and high temperature resistance, and is suitable for complex wearable application scenarios. At the same time, the use of mode merging technology greatly broadens the working bandwidth of the antenna, ensuring the electromagnetic performance of the antenna when it is deformed when worn. This 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 adopts a technical solution of a flexible dual-band dual-mode common aperture antenna applied in the wearable field:

[0006] The co-aperture antenna has a three-layer structure, the upper layer is a body surface working mode antenna and an external body working mode antenna, the middle layer is a flexible substrate, and the bottom layer is a metal ground; the flexible substrate is provided with an outer metal via pair, an inner metal via and an annularly distributed metal via, and the metal ground is connected to the body surface working mode antenna through the annularly distributed metal vias.

[0007] In the flexible substrate, the inner metal via is located at the center of the flexible substrate, the outer metal via pair is symmetrically located on the diameter passing through the inner metal via, and the annularly distributed metal vias are located inside the outer metal via pair with the inner metal via as the center.

[0008] The flexible substrate is made of polydimethylsiloxane (PDMS), which has good flexibility and high temperature resistance and is suitable for application scenarios of wearable devices.

[0009] A central via is provided at the center position of the metal ground, and two vias are provided on the diameter line of the central via to form a metal ground via pair; the center position of the central via corresponds to the center position of the inner metal via, and the metal ground via pair corresponds to the outer metal via pair, so as to be connected to the SMA connector during the testing of the in vitro working mode antenna and the surface working mode antenna.

[0010] The surface working mode antenna is symmetrically provided with two openings on its circumference, and the external working mode antenna has two symmetrical parts which are respectively located in the openings on both sides of the surface working mode antenna. The external working mode antenna operates in the 5.8GHz frequency band. The antenna operates in the far-field mode and has the characteristics of directional radiation, similar to the traditional microstrip antenna, and is used for communication between surface sensors and nodes in the environment.

[0011] The body surface working mode antenna is a metal disk with openings on both sides, which works in the 2.4 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.

[0012] The outer metal via pair is used as a feeding probe, with its upper part connected to the external working mode antenna and its lower part connected to the metal ground via pair; the inner metal via is used as a feeding probe, with its upper part connected to the surface working mode antenna and its lower part connected to the center via.

[0013] The surface working mode antenna works in TM02 mode. The lower part of the annularly distributed metal vias is connected to the metal ground, and the upper part is respectively connected to the surface working mode antenna and the upper external working mode antenna to stimulate the TM01 mode. The working bandwidth of the surface working mode is improved by mode merging.

[0014] There is a certain gap between the antenna in the body surface working mode and the antenna in the body external working mode to ensure that the two working modes have a high degree of isolation and to suppress the high-order modes excited by the coupling of the antenna in the body external working mode.

[0015] Beneficial effects: The present invention provides a compact dual - frequency and dual - mode common - aperture antenna. This antenna consists of two different antennas on one aperture plane, achieving two frequencies and two modes. Additionally, the antenna is based on a flexible substrate, having characteristics such as flexibility and high temperature resistance, and is suitable for complex wearable application scenarios. Meanwhile, the use of mode - merging technology greatly broadens the working bandwidth of the antenna, ensuring the electromagnetic performance of the antenna when deformed during wearing. This invention provides an effective solution for high - integration and compact wearable devices.

[0016] The present invention has the following prominent features compared with existing wearable antennas:

[0017] 1. The present invention has a more compact size. It has two frequency bands and two modes on the same aperture, simultaneously realizing an omnidirectional body - surface working - mode antenna in the 2.4 - GHz band and a directional off - body working - mode antenna in the 5.8 - GHz band.

[0018] 2. The antenna is composed of a flexible substrate and a copper film, enabling the antenna to not only maintain good electromagnetic performance but also have the characteristics of being bendable and high - temperature resistant, providing an effective solution for high - integration and compact wearable devices.

[0019] 3. By introducing annularly - distributed metal vias to connect the metal ground and the upper - layer body - surface working - mode antenna to excite the TM01 mode, which is merged with the TM02 mode of the body - surface working - mode antenna itself, the working bandwidth of the body - surface working - mode is increased, and the body - surface working - mode antenna still has good omnidirectional radiation characteristics, ensuring the electromagnetic performance of the antenna when deformed during wearing. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 It is a top view of the present invention.

[0022] Figure 3 It is a front view of the present invention.

[0023] Figure 4 It is a bottom view of the present invention.

[0024] Figure 5 It is the S - parameter of the antenna of the present invention.

[0025] Figure 6 It is the S - parameter of the antenna of the present invention under different curvature radii.

[0026] Figure 7 It is the far - field antenna radiation pattern of the present invention. Among them, Figure 7Among them, (a) is the radiation pattern of the xoy plane at 2.4 GHz, Figure 7 Among them, (b) is the radiation pattern of the xoz plane at 2.4 GHz, Figure 7 Among them, (c) is the radiation pattern of the xoz plane at 5.8 GHz, Figure 7 Among them, (d) is the radiation pattern of the yoz plane at 5.8 GHz.

[0027] In the figure: there are flexible substrate 1, metal ground 2, metal ground via pair 21, center via 22, body surface working mode antenna 3, external body working mode antenna 4, external metal via pair 5, internal metal via 6, and annularly distributed metal vias 7. Specific embodiments

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] As Figure 1 , 2 , 3 and 4 show, the flexible dual-band dual-mode common aperture antenna applied to a wearable device, the overall structure includes two antennas with different frequencies and different modes on the upper layer, the flexible substrate 1 in the middle and the metal ground 2 made of copper film at the bottom; the two antennas are respectively composed of the body surface working mode antenna 3 and the external body working mode antenna 4, as Figure 1 shown. The antennas work in the 2.4 GHz band and the 5.8 GHz band respectively, corresponding to two modes. For the external body working mode antenna 4, it is a deformation of a traditional microstrip antenna, working in the main mode TM10 mode, so it has a directional radiation pattern and can be used for communication with external nodes. For the body surface working mode antenna 3, it is composed of a metal disc-shaped antenna with openings on both sides. The antenna itself works in the TM02 mode and has an omnidirectional radiation pattern for communication between body surface sensors. At the same time, an annularly distributed metal via 7 is introduced to connect the metal ground 2 and the upper body surface working mode antenna 3 to excite the TM01 mode, and this working mode also shows an omnidirectional radiation characteristic. By combining the TM01 and TM02 working modes, while ensuring that the antenna generates omnidirectional radiation, the working bandwidth of the antenna is greatly improved, and the electromagnetic performance of the antenna when worn and deformed is ensured. The flexible substrate 1 used is made of polydimethylsiloxane (PDMS), has good flexibility and high temperature resistance, and is suitable for the application scenario of wearable devices. The external metal via pair 5 and the internal metal via 6 are the feeding probes of the external body working mode antenna 4 and the body surface working mode antenna 3 respectively.

[0030] Its structure is specifically as follows: The co-aperture antenna has a three-layer structure. The upper layer is the body surface working mode antenna 3 and the extracorporeal working mode antenna 4. The middle layer is the flexible substrate 1, and the bottom layer is the metal ground 2. The flexible substrate 1 is provided with an external metal via pair 5, an internal metal via 6, and a circularly distributed metal via 7. The metal ground 2 is connected to the body surface working mode antenna 3 through the circularly distributed metal via 7. In the flexible substrate 1, the internal metal via 6 is located at the center of the flexible substrate 1. The external metal via pair 5 is symmetrically located on the diameter passing through the internal metal via 6. The circularly distributed metal via 7 is centered on the internal metal via 6 and is located within the external metal via pair 5. The flexible substrate 1 is made of polydimethylsiloxane PDMS, which has good flexibility and high temperature resistance and is suitable for the application scenario of wearable devices.

[0031] A central via 22 is provided at the center position of the metal ground 2. Two vias are provided on the diameter line of the central via 22 to form a metal ground via pair 21. The center position of the central via 22 corresponds to the center position of the internal metal via 6, and the metal ground via pair 21 corresponds to the external metal via pair 5, so as to connect with the SMA connector during the testing of the extracorporeal working mode antenna 4 and the body surface working mode antenna 3.

[0032] Two openings are symmetrically provided on the circumference of the body surface working mode antenna 3. The extracorporeal working mode antenna 4 has two symmetrical parts and is respectively located in the openings on both sides of the body surface working mode antenna 3. The extracorporeal working mode antenna 4 operates in the 5.8 GHz frequency band. 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. The body surface working mode antenna 3 is a metal disc with openings on both sides and operates in the 2.4 GHz frequency band. This antenna operates in the far-field mode and has the characteristic of omnidirectional radiation and is used for communication between body surface sensors. The body surface working mode antenna 3 operates in the TM02 mode. The lower part of the circularly distributed metal via 7 is connected to the metal ground 2, and the upper parts are respectively connected to the body surface working mode antenna 3 and the upper extracorporeal working mode antenna 4, exciting the TM01 mode, and improving the working bandwidth of the body surface working mode through mode merging. There is a certain gap between the body surface working mode antenna 3 and the extracorporeal working mode antenna 4 to ensure a high isolation degree between the two working modes and suppress the high-order modes excited by coupling of the extracorporeal working mode antenna.

[0033] The external metal via pair 5 serves as a feeding probe. Its upper part is connected to the extracorporeal working mode antenna 4, and its lower part is connected to the metal ground via pair 21. The internal metal via 6 serves as a feeding probe. Its upper part is connected to the body surface working mode antenna 3, and its lower part is connected to the central via 22.

[0034] To facilitate the description of the design process of each structural parameter, given the structural parameters, the overall size of the antenna is 130mm×130mm×2mm. The antenna is designed on a single-layer polydimethylsiloxane (PDMS) substrate with a dielectric constant of 2.9 and a loss tangent angle of 0.001. For the body surface working mode antenna operating in the 2.4GHz band, it is composed of a metal disc-shaped antenna with openings on both sides. The radius of the disc-shaped antenna is 41mm, and the removed angle is 36°. The antenna itself operates in the TM02 mode and has an omnidirectional radiation pattern. The inside of the metal disc is connected to the ground plane by conductive vias, exciting the TM01 mode, which also has an omnidirectional radiation characteristic. By combining the TM01 and TM02 operating modes, while ensuring that the antenna generates omnidirectional radiation, the operating bandwidth of the antenna is greatly improved. For the in vitro working mode antenna in the 5.8GHz band, it is designed at the opening of the body surface working mode antenna, so that the overall structure of the antenna can be basically unchanged while realizing the in vitro working mode in the 5.8GHz band. It should be noted that a certain gap should be ensured between the antennas of the two working modes to reduce the coupling between the two antennas and suppress the high-order modes of the body surface working mode antenna excited by coupling when the in vitro working mode antenna operates.

[0035] Finally, the simulated S-parameters of the two far-field antennas are as Figure 5 shown. Since the in vitro working mode antenna in this invention is a set of symmetric antennas, only one port is simulated here. From Figure 5 it can be seen that the body surface working mode antenna achieves a bandwidth of 180MHz in the range of 2.33 - 2.51GHz, and the in vitro working mode antenna achieves a bandwidth of 200MHz in the range of 5.7 - 5.9GHz. The two antennas achieve isolation degrees of 23dB and 30dB respectively in the two frequency bands. Under different curvature radii, the S11 parameters of the two working modes of this antenna are as Figure 6 shown. It can be observed that as the bending radius decreases, the operating frequency bands of the antennas in both working modes shift to lower frequencies, but the reduction degrees are within an acceptable range.

[0036] Regarding the far-field radiation patterns of the two antennas, as Figure 7 shown, it can be seen from the figure that the antenna in the body surface working mode achieves an omnidirectional radiation characteristic, while the antenna in the in vitro working mode achieves a directional radiation characteristic. The simulation results verify the feasibility of the two antennas in their respective modes.

[0037] High-frequency simulation software such as HFSS from Ansoft Corporation and Microwave Studio CST from CST Corporation are selected. The curves obtained above are obtained under given conditions. Similar curves can also be obtained by changing the structural parameters.

[0038] 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 modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A flexible dual-band dual-mode common aperture antenna for use in the wearable field, characterized in that: The co-aperture antenna has a three-layer structure, wherein the upper layer is a body surface working mode antenna (3) and an external body working mode antenna (4), the middle layer is a flexible substrate (1), and the bottom layer is a metal ground (2); the flexible substrate (1) is provided with an outer metal via pair (5), an inner metal via (6), and an annularly distributed metal via (7); the metal ground (2) and the body surface working mode antenna (3) are connected via the annularly distributed metal via (7); The body surface working mode antenna (3) is symmetrically provided with two openings on its circumference, and the body external working mode antenna (4) has two symmetrical parts which are respectively located in the openings on both sides of the body surface working mode antenna (3); In the flexible substrate (1), the inner metal via (6) is located at the center of the flexible substrate (1), the outer metal via pair (5) is symmetrically located on a diameter passing through the inner metal via (6), and the annularly distributed metal vias (7) are located within the outer metal via pair (5) with the inner metal via (6) as the center.

2. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 1, characterized in that: The flexible substrate (1) is made of polydimethylsiloxane (PDMS), which has good flexibility and high temperature resistance and is suitable for application scenarios of wearable devices.

3. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 1, characterized in that: A central via hole (22) is provided at the center position of the metal ground (2), and two via holes are provided on the diameter line of the central via hole (22) to form a metal ground via hole pair (21); the center position of the central via hole (22) corresponds to the center position of the inner metal via hole (6), and the metal ground via hole pair (21) corresponds to the position of the outer metal via hole pair (5), so that the antenna (4) in the external working mode and the antenna (3) in the surface working mode can be connected to the SMA connector during testing.

4. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 1, characterized in that: The external working mode antenna (4) operates in the 5.8 GHz frequency band. The antenna operates in a far-field mode and has the characteristic of directional radiation. It is used for communication between the body surface sensor and the nodes in the environment.

5. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 1, characterized in that: The body surface working mode antenna (3) is a metal disk with openings on both sides, and operates in the 2.4 GHz frequency band. The antenna operates in a far-field mode and has an omnidirectional radiation characteristic, and is used for communication between body surface sensors.

6. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 1, characterized in that: The outer metal via pair (5) serves as a feeding probe, with its upper portion connected to the external working mode antenna (4) and its lower portion connected to the metal ground via pair (21); the inner metal via (6) serves as a feeding probe, with its upper portion connected to the surface working mode antenna (3) and its lower portion connected to the center via (22).

7. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 1, characterized in that: The body surface working mode antenna (3) works in the TM02 mode. The lower part of the annularly distributed metal vias (7) is connected to the metal ground (2), and the upper part is connected to the body surface working mode antenna (3), so as to stimulate the TM01 mode, thereby increasing the working bandwidth of the body surface working mode through mode merging.

8. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 5, characterized in that: There is a gap between the body surface working mode antenna (3) and the external working mode antenna (4) to ensure isolation between the two working modes and to suppress high-order modes excited by coupling of the external working mode antenna.

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