Flexible dual-band dual-mode common-aperture antenna applied to wearable field

Abstract

The invention discloses a flexible dual-band dual-mode common-caliber antenna applied to the wearable field, which comprises a body surface working mode antenna (3), an in-vitro working mode antenna (4), a flexible substrate (1) at the middle layer and a metal ground (2) made of a copper film at the bottom layer, and is characterized in that the flexible substrate (1) is internally provided with an outer metal via hole pair (5) and an inner metal via hole (6); annularly-distributed metal through holes (7) are formed between the metal ground (2) and the body surface working mode antenna (3), and the annularly-distributed metal through holes (7) are located in the flexible substrate (1). The common-aperture antenna is compact in structure, two antennas in different working modes are integrated in the same aperture, and the working bandwidth of the antenna in the body surface working mode is improved through mode combination, so that the common-aperture antenna is more suitable for working on a flexible substrate. The common-aperture antenna provides an effective solution 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 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: 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] Beneficial effects: The present invention provides a compact dual-frequency dual-mode common aperture antenna, which is composed of two different antennas on one aperture surface, realizing two frequencies and 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. The invention provides an effective solution for highly integrated and compact wearable devices.

[0015] Compared with the existing wearable antenna, the present invention has the following outstanding features: 1. The present invention has a more compact size, and has two frequency bands and two modes in the same aperture, and simultaneously realizes an omnidirectional surface working mode antenna in the 2.4 GHz frequency band and a directional external working mode antenna in the 5.8 GHz frequency band.

[0016] 2. The antenna is composed of a flexible substrate and a copper film, which not only maintains good electromagnetic properties, but also has the characteristics of flexibility and high temperature resistance, providing an effective solution for highly integrated and compact wearable devices.

[0017] 3. By introducing circularly distributed metal vias to connect the metal ground and the upper surface working mode antenna, the TM01 mode is stimulated and merged with the TM02 mode of the surface working mode antenna itself, thereby improving the working bandwidth of the surface working mode and making the surface working mode antenna still have good omnidirectional radiation characteristics, thereby ensuring the electromagnetic performance of the antenna when it is deformed while being worn. 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 is the S parameter of the antenna of the present invention.

[0023] Figure 6 : S parameters of the antenna of the present invention at different curvature radii.

[0024] Figure 7 is the far-field antenna radiation pattern of the present invention. Figure 7 (a) is the radiation pattern of the xoy plane at 2.4GHz. Figure 7(b) is the radiation pattern of the xoz surface at 2.4GHz. Figure 7 (c) is the radiation pattern of the xoz surface at 5.8GHz. Figure 7 (d) in the figure is the radiation pattern of the yoz plane at 5.8 GHz.

[0025] The figure includes: flexible substrate 1, metal ground 2, metal ground via pair 21, central via 22, surface working mode antenna 3, external working mode antenna 4, outer metal via pair 5, inner metal via 6, and ring-shaped metal vias 7. DETAILED DESCRIPTION

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

[0027] like Figure 1 , 2 As shown in , 3 and 4, the flexible dual-band dual-mode common aperture antenna used in wearable devices has an overall structure including two antennas of different frequencies and modes on the upper layer, a flexible substrate 1 in the middle and a metal ground 2 made of copper film on the bottom; the two antennas are respectively composed of an antenna 3 working in a body surface working mode and an antenna 4 working in a body external working mode, as shown in FIG. Figure 1 As shown. The antennas work in the 2.4 GHz frequency band and the 5.8 GHz frequency band, respectively, corresponding to two modes. For the antenna 4 working in the external working mode, it is a deformation of the traditional microstrip antenna, working in the main mode TM10 mode, so it has a directional radiation mode and can be used to communicate with external nodes. For the antenna 3 working in the body surface working mode, it is composed of a metal disc antenna with openings on both sides. The antenna itself works in the TM02 mode and has an omnidirectional radiation mode, which is used for communication between body surface sensors. At the same time, the introduction of the annularly distributed metal via 7 connects the metal ground 2 and the upper layer of the body surface working mode antenna 3 to stimulate the TM01 mode. This working mode also exhibits omnidirectional radiation characteristics. By combining the two working modes of TM01 and TM02, while ensuring that the antenna produces omnidirectional radiation, the working bandwidth of the antenna is greatly improved, and the electromagnetic performance of the antenna when it is deformed when worn is guaranteed. The flexible substrate 1 used is made of polydimethylsiloxane (PDMS), which has good flexibility and high temperature resistance, and is suitable for the application scenarios of wearable devices. The outer metal via pair 5 and the inner metal via 6 are respectively the feeding probes of the antenna 4 in the external working mode and the antenna 3 in the surface working mode.

[0028] Its structure is specifically as follows: the co-aperture antenna has a three-layer structure, the upper layer is the surface working mode antenna 3 and the external 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 outer metal via pair 5, an inner metal via 6 and an annularly distributed metal via 7, and the metal ground 2 is connected to the surface working mode antenna 3 through the annularly distributed metal via 7. In the flexible substrate 1, the inner metal via 6 is located at the center of the circle of the flexible substrate 1, the outer metal via pair 5 is symmetrically located on the diameter passing through the inner metal via 6, and the annularly distributed metal via 7 is located in the outer metal via pair 5 with the inner metal via 6 as the center. 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.

[0029] A center via 22 is provided at the center position of the metal ground 2, and two vias are provided on the diameter line of the center via 22 to form a metal ground via pair 21; the center position of the center via 22 corresponds to the center position of the inner metal via 6, and the metal ground via pair 21 corresponds to the position of the outer metal via pair 5, so that the in vitro working mode antenna 4 and the surface working mode antenna 3 can be connected to the SMA connector during testing.

[0030] The surface working mode antenna 3 is symmetrically provided with two openings on the circumference, and the external working mode antenna 4 has two symmetrical parts and is respectively located in the openings on both sides of the surface working mode antenna 3. The external working mode antenna 4 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. The surface working mode antenna 3 is a metal disk with openings on both sides, which operates in the 2.4GHz frequency band. The antenna operates in the far-field mode and has the characteristics of omnidirectional radiation, which is used for communication between surface sensors. The surface working mode antenna 3 operates in the TM02 mode, and the lower part of the annularly distributed metal vias 7 is connected to the metal ground 2, and the upper part is respectively connected to the surface working mode antenna 3 and the upper external working mode antenna 4, which excites the TM01 mode, and improves the working bandwidth of the surface working mode by mode merging. There is a certain gap between the surface working mode antenna 3 and the external working mode antenna 4 to ensure that the two working modes have a high degree of isolation and suppress the high-order modes excited by the external working mode antenna.

[0031] The outer metal via pair 5 is used as a feeding probe, with its upper part connected to the external working mode antenna 4 and its lower part connected to the metal ground via pair 21; the inner metal via 6 is used as a feeding probe, with its upper part connected to the surface working mode antenna 3 and its lower part connected to the center via 22.

[0032] In order to explain the design process of each structural parameter, given the structural parameters, the total size of the antenna is 130mm ´ 130mm ´ 2mm, and the antenna is designed on a single-layer polydimethylsiloxane (PDMS) substrate with a dielectric constant of 2.9 and a loss tangent of 0.001. For the on-body working mode antenna working in the 2.4GHz frequency band, it is composed of a metal disc antenna with openings on both sides. The radius of the disc antenna is 41mm, and the removal angle is 36°. The antenna itself works in the TM02 mode and has an omnidirectional radiation mode. The inside of the metal disc is connected to the floor with a conductive via to stimulate the TM01 mode, which also has omnidirectional radiation characteristics. By merging the two working modes of TM01 and TM02, the working bandwidth of the antenna is greatly improved while ensuring that the antenna produces omnidirectional radiation. For the on-body working mode antenna of the 5.8GHz frequency band, it is designed at the opening of the on-body working mode antenna, so that the on-body working mode of the 5.8GHz frequency band can be realized without basically changing the overall structure of the antenna. It is worth noting that a certain gap should be ensured between the antennas of the two working modes to reduce the coupling between the two antennas and to suppress the coupling excitation of the high-order modes of the antenna of the surface working mode when the antenna of the external working mode is working.

[0033] Finally, the simulated S parameters of the two far-field antennas are as follows: Figure 5 As shown. Since the in vitro working mode antenna in the invention is a set of symmetrical antennas, only one of the ports is simulated here. Figure 5 It can be seen that the antenna in the surface working mode achieves a bandwidth of 180MHz at 2.33-2.51GHz, and the antenna in the external working mode achieves a bandwidth of 200MHz at 5.7-5.9GHz. The two antennas achieve 23dB and 30dB isolation in the two frequency bands respectively. At different curvature radii, the S11 parameters of the two working modes of the antenna are as follows: Figure 6 It can be observed that as the bending radius decreases, the working frequency bands of the antennas in both working modes shift toward low frequencies, but the degree of reduction is within an acceptable range.

[0034] The far-field radiation patterns for both antennas are as follows 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 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), and the metal ground (2) and the body surface working mode antenna (3) are connected via the annularly distributed metal via (7).

2. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 1, characterized in that: 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.

3. 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.

4. 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.

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 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).

6. 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.

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) 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.

8. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 2, 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).

9. 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 respectively connected to the body surface working mode antenna (3) and the upper external working mode antenna (4), thereby stimulating the TM01 mode and improving the working bandwidth of the body surface working mode through mode merging.

10. The flexible dual-band dual-mode common aperture antenna for use in the wearable field according to claim 7, 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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