Three-band circularly polarized flexible microstrip antenna and wearable device

Abstract

The invention belongs to the field of satellite mobile communication, and particularly provides a three-frequency-band circularly polarized flexible microstrip antenna and wearable equipment, used radiation patches are superconducting fabrics, a dielectric substrate is made of flexible felt materials and has the overall flexibility characteristic, so that the wearing comfort is ensured, the mode that two layers of radiation patches are stacked is adopted, and the antenna is more flexible. The upper-layer patch is subjected to special treatment such as branch knot loading and slotting to obtain a dual-band right-handed circularly polarized radiation characteristic, the parasitic patch is introduced to the upper surface of the upper-layer dielectric substrate to enhance the axial ratio bandwidth of the upper-layer patch, and the lower-layer patch is subjected to corner cutting treatment to obtain a left-handed circularly polarized radiation characteristic. And the isolation degree between the two ports is enhanced by introducing the metal short-circuit through hole. And the upper-layer patch and the lower-layer patch are fed by using a coaxial cable. Finally, the section of the antenna is only 0.05 lambda0, and the antenna is simple in structure, convenient to manufacture, good in performance and more convenient to wear on a human body, and meets the performance requirements of a Beidou navigation system.

Description

Technical Field

[0001] The present invention belongs to the field of satellite mobile communication, and particularly relates to a triple-band circularly polarized flexible microstrip antenna and a wearable device. Background Art

[0002] Circularly polarized microstrip antennas are widely used in modern wireless communication scenarios due to their unique advantages such as reducing polarization mismatch, low profile, and easy integration. As is well known, China's Beidou Global Navigation Satellite System (BDS) has been widely used at present. For the working frequency band BDS-1 of the Beidou navigation system, its required uplink frequency is 1.615 GHz and has the characteristic of left-handed circular polarization radiation; while the downlink frequency is 2.492 GHz and has the characteristic of right-handed circular polarization radiation. At the same time, for another working frequency band BDS-3 of the Beidou navigation system, the antenna must also have right-handed circular polarization radiation waves at 1.575 GHz. These requirements pose two severe challenges to the antenna design: The antenna must have three working frequency bands. That is to say, the impedance matching bandwidth of the antenna must cover 1.575 GHz, 1.615 GHz, and 2.492 GHz. At the same time, the antenna must ensure good circular polarization radiation characteristics near these three frequency bands. It should be noted that at least two modes are required to ensure the circular polarization radiation characteristics. Therefore, it is challenging to simultaneously apply six working modes to achieve the circular polarization radiation characteristics of the triple band.

[0003] The low frequency band has two radiation fields with different polarization directions. Near 1.575 GHz and 1.615 GHz, the antenna must have right-handed and left-handed circular polarization radiation characteristics respectively. Due to the too small frequency ratio, it is very challenging to achieve different polarization characteristics.

[0004] In addition, in addition to the above challenges, the Beidou navigation system still has more stringent requirements for the form of the antenna. Since the Beidou navigation system ensures real-time positioning of the human body during field operations or outdoor activities, the antenna usually needs to be worn by the human body. Therefore, the materials used for the antenna not only need to ensure excellent performance, but also need to ensure the comfort and portability of human wearing. Adopting a combination of felt and superconducting fabric to prepare a wearable flexible antenna is a way to meet the wearing requirements. However, in terms of current research work, there is temporarily no design that combines wearability with triple-band circular polarization performance.

[0005] In summary, the above challenges have not been effectively addressed in existing research work. The Chinese patent with the publication number CN111682305A provides a low-profile circularly polarized microstrip antenna for satellite communication, which solves the problem of narrow beamwidth of existing satellite communication antennas. However, it focuses on single-band use. The Chinese patent with the publication number CN108832290A provides a three-arm circularly polarized antenna, which solves the problem of low gain of existing circularly polarized antennas. On the one hand, this patent also only focuses on single-band application. On the other hand, the radiation pattern of this patent presents a bidirectional radiation form, which causes inconvenience to satellite communication. The Chinese patent with the publication number CN112271439A provides a multi-patch circularly polarized microstrip antenna with a feeding network, which solves the problem of narrow half-power beam and axial ratio beam of existing circularly polarized antennas. This patent focuses more on improving radiation performance. However, it does not consider application in multiple frequency bands. In addition, the structural complexity and relatively high profile height make it difficult to be applied to satellite communication. The Chinese patent with the publication number CN110676568A provides a dual circularly polarized microstrip antenna with a back cavity, which solves the problem of low isolation of existing dual circularly polarized antennas. This patent focuses more on enhancing the axial ratio bandwidth and port isolation. However, its profile height is too high and the application frequency band is also single.

[0006] In summary, although it is possible to attempt to use a broadband antenna to cover three frequency bands. However, the need for circularly polarized radiation fields with two different polarization directions in the low-frequency range cannot be satisfied at this time. In addition, the wearable characteristics of the antenna are not demonstrated in the above work. Summary of the Invention

[0007] To solve the problems existing in the prior art, the present invention provides a three-band circularly polarized flexible microstrip antenna. By stacking radiation patches and using dual-port feeding, the radiation characteristics of three-band circular polarization are achieved. The introduced parasitic patch structure significantly enhances the axial ratio bandwidth at low frequencies. The patches and substrates used are both flexible objects, where the patches are made of superconducting fabric and the substrates are made of felt, which is convenient for human body to wear, thus meeting the working requirements of Beidou antennas.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a triple-band circularly polarized flexible microstrip antenna, comprising an upper patch, an upper dielectric substrate, a lower patch, a lower dielectric substrate, and a metal ground plane arranged in sequence from top to bottom; the upper patch is connected to an upper feeding coaxial cable; the upper dielectric substrate and the lower dielectric substrate are connected by a textile thread; a plurality of metal shorting vias are provided between the lower patch and the metal ground plane; the lower patch is connected to a lower feeding coaxial cable, and the metal ground plane serves as the feeding ground for the upper patch and the lower patch; the upper patch is formed by slitting a square patch and adding stubs; parasitic patches are arranged on the sides of the upper patch, and the parasitic patches are formed by splicing a plurality of different rectangular patches, and the lower patch is a rectangular patch with chamfered corners.

[0009] The upper patch, the parasitic patches, and the lower patch are all made of metal fabric.

[0010] Further, both the upper dielectric substrate and the lower dielectric substrate are made of flexible felt material.

[0011] Further, a first stub, a second stub, a third stub, and a fourth stub are respectively arranged corresponding to the four sides of the upper patch. The first stub, the second stub, the third stub, and the fourth stub are all bent by 90°. The first stub, the second stub, and the fourth stub are bent counterclockwise, and the third stub is bent clockwise. Rectangular open slots are provided between the first stub and the second stub, and between the second stub and the third stub. A rectangular slot is provided in the middle of the upper patch; a fifth stub is provided between the third stub and the fourth stub, and the fifth stub is bent clockwise by 90°. A sixth stub is provided between the fourth stub and the first stub, and the sixth stub is rectangular.

[0012] Further, the upper patch and the lower patch are respectively fed at the bottom by two coaxial cables.

[0013] Further, the inner conductor of the upper feeding coaxial cable passes through the lower dielectric substrate and the upper dielectric substrate and is connected to the upper patch.

[0014] Further, the lower patch is formed by cutting off four corners of a rectangular patch.

[0015] Further, one third metal shorting via hole is provided and located at the center position of the lower patch; the first metal shorting via hole and the three fourth metal shorting via holes are respectively located on both sides of the third metal shorting via hole, and one fifth metal shorting via hole and the fourth metal shorting via holes are located on the same side of the third metal shorting via hole; the three fourth metal shorting via holes are of the same size; the fifth metal shorting via hole is closer to the third metal shorting via hole than the fourth metal shorting via hole; one second metal shorting via hole is provided and located below the parasitic patch; the radii of the third metal shorting via hole, the fourth metal shorting via hole, the third metal shorting via hole, the fourth metal shorting via hole, the second metal shorting via hole, and the first metal shorting via hole decrease in sequence, and the radii of the first metal shorting via hole and the fifth metal shorting via hole are the same.

[0016] Further, the parasitic patch includes a first patch, a second patch, a third patch, a fourth patch, a fifth patch, and a sixth patch. The second patch and the third patch are located on both sides of the first patch, the second patch and the third patch are perpendicular to the first patch, and the width of the second patch is smaller than that of the third patch; the second patch and the third patch are connected to the first patch at the same length position, and the third patch, the fourth patch, the fifth patch, and the sixth patch are connected in sequence; the sixth patch is parallel to the edge of the upper patch, the fifth patch is bent clockwise by 90° relative to the sixth patch, the fourth patch is bent clockwise by 90° relative to the fifth patch, and the first patch and the fifth patch are respectively parallel to the two segments of the first stub bent.

[0017] The present invention can also provide a wearable device, including the three-band circularly polarized flexible microstrip antenna as described above.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention enables the proposed microstrip antenna to cover three different frequency bands required by the Beidou Navigation System by means of chamfering, slitting, adding branches, and stacking patches, and each frequency band has circular polarization characteristics. In particular, the parasitic patches used enhance the axial ratio bandwidth in the low-frequency band; the antenna has different circular polarization characteristics at the frequencies of 1.575 GHz and 1.615 GHz. It is worth noting that it is quite challenging to achieve different circular polarization rotation radiations near two very close frequencies. The present invention successfully realizes the circular polarization radiation characteristics with different rotation directions under the condition of an extremely low frequency ratio by using a dual-port method; specifically, the parasitic patches expand the axial ratio bandwidth in the low-frequency range by enhancing the bandwidth of the mode; the lower-layer patch radiates left-handed circularly polarized waves by means of chamfering; the isolation between the upper-layer feeding coaxial cable and the lower-layer feeding coaxial cable is enhanced by metal shorting vias; the upper-layer patch and the lower-layer patch are respectively bottom-fed by two coaxial cables, and radiation waves with two polarization characteristics are realized in the range of close frequencies. In addition, the additionally added parasitic patches can effectively expand the low-frequency axial ratio bandwidth of the antenna; the metal shorting vias under the lower-layer patch can effectively affect the electric field distribution of the patch, thereby significantly reducing the coupling degree between the upper and lower patches; ensuring a high isolation level between ports enables the antenna to operate normally in the adjacent frequency bands.

[0019] Furthermore, the patches used are composed of metal fabrics, and both the upper-layer dielectric substrate and the lower-layer dielectric substrate adopt flexible felt materials, and these two flexible objects ensure the comfort of human body wearing when the antenna operates normally.

[0020] The above four beneficial effects ensure that the present invention is applicable to the Beidou Navigation System. Description of the Drawings

[0021] Figure 1 It is the overall three-dimensional structure diagram of the triple-band circularly polarized flexible microstrip antenna of the present invention.

[0022] Figure 2 It is the top view of the upper-layer dielectric substrate and the radiation patch.

[0023] Figure 3 It is the top view of the lower-layer dielectric substrate and the radiation patch.

[0024] Figure 4 It is the S-parameter curve diagram of the triple-band circularly polarized antenna of the present invention.

[0025] Figure 5 It is the axial ratio parameter curve diagram of the triple-band circularly polarized antenna of the present invention.

[0026] Figure 6 It is the actual gain curve diagram of the triple-band circularly polarized antenna of the present invention.

[0027] Among them, 1 - upper patch, 2 - upper feed coaxial cable, 3 - parasitic patch, 4 - upper dielectric substrate, 5 - lower feed coaxial cable, 61 - first metal shorting via, 62 - second metal shorting via, 63 - third metal shorting via, 64 - fourth metal shorting via, 65 - fifth metal shorting via, 7 - lower patch, 8 - lower dielectric substrate, 9 - metal ground plane. Detailed implementation manners

[0028] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", "one side", "one end", "one side", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0030] The present invention provides a low-profile triple-band circularly polarized flexible microstrip antenna for the Beidou navigation system. Its overall structure and upper and lower layer structures are respectively as Figure 1 、 Figure 2 and Figure 3As shown, it specifically includes: the upper patch 1, the upper feeding coaxial cable 2, the parasitic patch 3, the upper dielectric substrate 4, the lower feeding coaxial cable 5, the lower patch 7, the lower dielectric substrate 8, and the metal floor 9. Among them, a first metal shorting via 61, a second metal shorting via 62, a third metal shorting via 63, a fourth metal shorting via 64, and a fifth metal shorting via 65 are provided between the lower patch 7 and the metal floor 9. The upper patch 1 is pasted on the upper surface of the upper dielectric substrate 4, and the upper feeding coaxial cable 2 is connected to the upper patch 1. The parasitic patch 3 is also pasted on the upper surface of the upper dielectric substrate 4; the lower patch 7 and the metal floor 9 are respectively pasted on the upper surface and the lower surface of the lower dielectric substrate 8; the upper dielectric substrate 4 and the lower dielectric substrate 8 are connected by a textile thread.

[0031] Reference Figure 3 , where the number of the first metal shorting via 61 is one, the radius is 1 mm, and the distances from the upper edge and the left edge of the lower patch 7 are 24.1 mm and 27 mm respectively; the number of the second metal shorting via 62 is one, the radius is 1.5 mm, and the distances from the upper edge and the right edge of the lower patch 7 are 37.1 mm and 20 mm respectively; the number of the third metal shorting via 63 is one, the radius is 2.5 mm, and it is located at the center position of the lower patch 7; the number of the fourth metal shorting via 64 is three, the radii are all 1.7 mm, and the distance from the lower edge and the left edge of the lower patch 7 of the first metal via counted from left to right is 22.1 mm and 27.2 mm respectively, and the spacing between the three metal vias is 5 mm; the number of the fifth metal shorting via is one, the radius is 1 mm, and the distances from the lower edge and the left edge of the lower patch 7 are 24 mm and 22 mm respectively.

[0032] It should be noted that both the upper patch 1 and the lower patch 7 in the present invention adopt the form of rectangular patches. Among them, the upper patch 1 realizes the right-handed circular polarization radiation in the low-frequency band and the high-frequency band by means of stub loading and slotting. The parasitic patch is used to enhance the axial ratio bandwidth of the low-frequency band of the upper patch, and the lower patch 7 realizes the left-handed circular polarization radiation in the low-frequency band by means of chamfering and slotting. Since two ports are used to feed the upper and lower patches respectively, the isolation between the ports must be considered. A series of metal shorting vias are loaded between the lower patch 7 and the metal floor 9 to significantly enhance the isolation between the ports.

[0033] In the present invention, the structure of the upper antenna radiator is as Figure 2As shown. Among them, the overall size of the upper patch 1 without branches is 39 mm × 39 mm. Adjusting the size of the upper patch 1 can effectively change the operating frequency of the upper patch 1. In order to enhance the axial ratio bandwidth of the upper antenna radiator, a corresponding parasitic patch 3 is added. The overall length of the parasitic patch 3 is 52.1 mm and it is composed of a series of different rectangular patches merged together. The sizes of the upper dielectric substrate 4 and the lower dielectric substrate 8 are both 120 mm × 90 mm × 3 mm. The structure of the lower antenna radiator is as Figure 3 shown. Among them, the size of the lower patch 7 is 63.9 mm × 59.35 mm. It should be noted that a series of metal shorting vias are located below the lower patch 7 to significantly enhance the isolation between the two ports. The size and position of the metal shorting vias are the key parameters affecting the coupling between the ports. The metal ground plane 9 is located on the lower surface of the lower dielectric substrate 8 and serves as the feeding ground for the upper patch 1 and the lower patch 7. Among them, the inner conductor of the upper coaxial cable 2 passes through the metal ground plane 9, the upper dielectric substrate 4 and the lower dielectric substrate 8 and is connected to the upper patch 1; the inner conductor of the lower coaxial cable 5 is directly connected to the lower patch 7, thereby realizing the characteristic of dual-port operation. The antenna itself has a flexible feature, which is convenient for wearing and using.

[0034] The four sides of the upper patch 1 are respectively provided with a first branch, a second branch, a third branch and a fourth branch. The first branch, the second branch, the third branch and the fourth branch are all bent by 90°. The first branch, the second branch and the fourth branch are all bent counterclockwise, and the third branch is bent clockwise. A rectangular opening slot is opened between the first branch and the second branch, and between the second branch and the third branch. A rectangular slot is opened in the middle of the upper patch 1; a fifth branch is provided between the third branch and the fourth branch, and the fifth branch is bent clockwise by 90°. A sixth branch is provided between the fourth branch and the first branch, and the sixth branch is rectangular.

[0035] The parasitic patch 3 includes a first patch, a second patch, a third patch, a fourth patch, a fifth patch and a sixth patch. The second patch and the third patch are located on both sides of the first patch. The second patch and the third patch are perpendicular to the first patch, and the width of the second patch is less than the width of the third patch; and the second patch and the third patch are connected to the same length position of the first patch. The third patch, the fourth patch, the fifth patch and the sixth patch are connected in sequence; the sixth patch is parallel to the edge of the upper patch 1, the fifth patch is bent clockwise by 90° relative to the sixth patch, the fourth patch is bent clockwise by 90° relative to the fifth patch, and the first patch and the fifth patch are respectively parallel to the two sections of the first branch bent; the distance between the sixth patch and the edge of the upper patch 1 is 1.5 mm, and the distances between the first patch and the fifth patch and the first branch are 2 mm.

[0036] The above-mentioned low-profile triple-band circularly polarized microstrip antenna is simulated and tested, and the results are as Figure 4 、Figure 5 and Figure 6 as shown. The simulation results show that the final size of the antenna is 1λ0×0.75λ0×0.05λ0, where λ0 is the wavelength in free space at the highest operating frequency. Refer to Figure 4 , the bandwidths of the reflection coefficient of port 1 less than -10 dB are 1.558 - 1.592 GHz and 2.471 - 2.51 GHz respectively. For port 2, it is 1.602 - 1.644 GHz. Within the operating ranges of the three frequency bands, the isolation between port 1 and port 2 exceeds 13 dB, indicating that the decoupling effect between ports has been achieved. Refer to Figure 5 , when port 1 is excited, the 3 dB axial ratio bandwidths of the antenna are 1.568 - 1.579 GHz and 2.49 - 2.506 GHz respectively. It can be seen that there are two minimum axial ratio points near 1.575 GHz, which benefits from the introduction of parasitic patches. When port 2 is excited, the 3 dB axial ratio bandwidth of the antenna is 1.611 - 1.621 GHz. Generally speaking, the circular polarization characteristics of the antenna are good, meeting the requirements of the Beidou navigation system. Refer to Figure 6 , when port 1 is excited, the maximum right - hand circular polarization gains of the antenna around 1.575 GHz and 2.492 GHz can reach 8.1 dBic and 9.4 dBic respectively. When port 2 is excited, the maximum left - hand circular polarization gain of the antenna around 1.615 GHz can reach 10.6 dBic. It should be noted that when port 1 is excited, the gain near 1.575 GHz decreases slightly because the folded structure of parasitic patch 3 causes the mutual cancellation of currents flowing in different directions, reducing the lateral radiation ability of the antenna and thus resulting in a decrease in gain.

[0037] Based on the above embodiments, the present invention can also provide a wearable device, including the three - band circularly polarized flexible microstrip antenna as described above.

[0038] In summary, for the three - band circularly polarized flexible microstrip antenna provided by the present invention, the radiation patch used is a superconducting fabric, and the dielectric substrate is made of flexible felt material, generally having the characteristic of flexibility, thus ensuring the wearing comfort. The present invention adopts the form of stacking two layers of radiation patches, and the upper - layer patch is subjected to special treatments such as loading stubs and slits to obtain the right - hand circular polarization radiation characteristics in two frequency bands. Parasitic patches are introduced on the upper surface of the upper - layer dielectric substrate to enhance the axial ratio bandwidth of the upper - layer patch. The lower - layer patch is chamfered to obtain the left - hand circular polarization radiation characteristics, and metal short - circuit vias are introduced to enhance the isolation between the two ports. The upper - layer dielectric substrate and the lower - layer dielectric substrate are connected by textile threads and fed by coaxial cables. The cross - section of the present invention is only 0.05λ0, with a simple structure, easy to manufacture, good performance, and more convenient to be worn on the human body, meeting the performance requirements of the Beidou navigation system.

[0039] The above are only specific embodiments of the present invention. Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or alternative features with similar purposes; all the disclosed features, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any manner.

Claims

1. A triple-band circularly polarized flexible microstrip antenna, characterized in that The invention comprises an upper patch (1), an upper dielectric substrate (4), a lower patch (7), a lower dielectric substrate (8) and a metal floor (9) which are arranged in sequence from top to bottom; the upper patch (1) is connected to an upper feeding coaxial cable (2); the upper dielectric substrate (4) and the lower dielectric substrate (8) are connected by a textile thread; a plurality of metal short-circuit through holes are provided between the lower patch (7) and the metal floor (9); the lower patch (7) is connected to a lower feeding coaxial cable (5), and the metal floor (9) serves as a feeding ground for the upper patch (1) and the lower patch (7); the upper patch (1) is formed by slotting a square patch and adding branches; a parasitic patch (3) is provided on the side of the upper patch (1), and the parasitic patch (3) is formed by splicing a plurality of different rectangular patches, and the lower patch (7) is a rectangular patch with cut corners.

2. The triple-band circularly polarized flexible microstrip antenna according to claim 1, wherein The upper patch (1), the parasitic patch (3) and the lower patch (7) are all made of metal fabric.

3. The triple-band circularly polarized flexible microstrip antenna according to claim 1, wherein The upper dielectric substrate (4) and the lower dielectric substrate (8) are both made of flexible felt.

4. The triple-band circularly polarized flexible microstrip antenna according to claim 1, characterized in that The four sides of the upper patch (1) are respectively provided with a first branch, a second branch, a third branch and a fourth branch. The first branch, the second branch, the third branch and the fourth branch are all bent 90 degrees. The first branch, the second branch and the fourth branch are all bent counterclockwise, and the third branch is bent clockwise. A rectangular opening groove is provided between the first branch and the second branch, and between the second branch and the third branch. A rectangular groove is provided in the middle of the upper patch (1); a fifth branch is provided between the third branch and the fourth branch, and the fifth branch is bent 90 degrees clockwise. A sixth branch is provided between the fourth branch and the first branch, and the sixth branch is rectangular.

5. The triple-band circularly polarized flexible microstrip antenna according to claim 1, characterized in that, The upper patch (1) and the lower patch (7) are bottom-fed by two coaxial cables respectively.

6. The triple-band circularly polarized flexible microstrip antenna according to claim 1, characterized in that The inner conductor of the upper feeding coaxial cable (2) passes through the lower dielectric substrate (8) and the upper dielectric substrate (4) and is connected to the upper patch (1).

7. The triple-band circularly polarized flexible microstrip antenna according to claim 1, wherein The lower patch (7) is formed by cutting off the four corners of a rectangular patch.

8. The triple-band circularly polarized flexible microstrip antenna according to claim 1, characterized in that, A third metal short-circuit through hole (63) is provided and is located at the center of the lower patch (7); the first metal short-circuit through hole (61) and the three fourth metal short-circuit through holes (64) are respectively located on both sides of the third metal short-circuit through hole (63); a fifth metal short-circuit through hole (65) and the fourth metal short-circuit through hole (64) are located on the same side of the third metal short-circuit through hole (63); the three fourth metal short-circuit through holes (64) are of the same size; relative to the fourth metal short-circuit through hole (64), the fifth metal short-circuit through hole (65) is closer to the fourth metal short-circuit through hole (64). Near the third metal short-circuit through hole (63), a second metal short-circuit through hole (62) is opened, and the second metal short-circuit through hole (62) is located below the parasitic patch (3). The radii of the third metal short-circuit through hole (63), the fourth metal short-circuit through hole (64), the third metal short-circuit through hole (63), the fourth metal short-circuit through hole (64), the second metal short-circuit through hole (62), and the first metal short-circuit through hole (61) decrease in sequence, and the radii of the first metal short-circuit through hole (61) and the fifth metal short-circuit through hole (65) are the same.

9. The triple-band circularly polarized flexible microstrip antenna according to claim 1, characterized in that, The parasitic patch (3) includes a first patch, a second patch, a third patch, a fourth patch, a fifth patch, and a sixth patch. The second patch and the third patch are located on both sides of the first patch. The second patch and the third patch are perpendicular to the first patch, and the width of the second patch is less than the width of the third patch. Moreover, the second patch and the third patch are connected to the same length position of the first patch. The third patch, the fourth patch, the fifth patch, and the sixth patch are connected in sequence. The sixth patch is parallel to the edge of the upper-layer patch (1). The fifth patch is bent clockwise by 90° relative to the sixth patch, and the fourth patch is bent clockwise by 90° relative to the fifth patch. The first patch and the fifth patch are respectively parallel to the two segments of the first branch bent.

10. A wearable device, characterized in that, It includes the triple-band circularly polarized flexible microstrip antenna according to any one of claims 1-9.

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