A flexible antenna for wireless microwave power transmission

Abstract

This invention provides a flexible antenna for wireless microwave power transmission, belonging to the field of communication technology. It includes a dielectric substrate, a patch antenna element, a feed microstrip line, a coplanar waveguide, and a reflective ground plane. This invention solves the problems of high energy transmittance and low receiving efficiency of traditional coplanar waveguide antennas, as well as the low integration density of traditional microstrip antennas.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and in particular relates to a flexible antenna for wireless microwave power transmission. Background Technology

[0002] Microwave receiving antennas and rectifier circuits are important components of microwave power transmission systems. Especially as the receiving end, new types of receiving antennas with high energy harvesting and conversion efficiency, convenient and quick installation methods, easy conformal design with load equipment, and certain self-healing capabilities are of great value for the promotion and application of microwave power transmission. Compared with traditional reflector antennas and planar array antennas, they have greater flexibility and are an inevitable development trend in the future.

[0003] Existing traditional patch antennas are typically fabricated by etching metal patterns onto a rigid substrate. When the rigid substrate is subjected to external forces such as compression and bending, it is prone to deformation or even breakage. Therefore, the application of traditional antennas in various environments and complex scenarios is greatly limited: antenna devices are difficult to conform to design and cannot maintain stable performance after deformation. At the same time, traditional antennas also have problems such as large size and area, which greatly limits the application scenarios and application value of traditional antennas. Summary of the Invention

[0004] To address the aforementioned shortcomings in the existing technology, this invention provides a flexible antenna for wireless microwave power transmission. It achieves the design of a miniaturized, high-gain, high-efficiency, easily conformal flexible patch antenna unit for microwave power transmission that operates at 5.8 GHz and is suitable for use with load devices while also possessing a certain degree of adaptability.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This solution provides a flexible antenna for wireless microwave power transmission, including a dielectric substrate, a patch antenna element, a feed microstrip line, a coplanar waveguide, and a reflective ground plane;

[0007] The patch antenna element, the feed microstrip line, and the coplanar waveguide are all attached to the upper part of the dielectric substrate and in contact with the PI layer of the dielectric substrate. The reflective ground plane is attached to the lower part of the dielectric substrate. The feed microstrip line is led out from the lower part of the patch antenna element and passes through the coplanar waveguide to connect to an external power receiver. The feed microstrip line, the coplanar waveguide, and the reflective ground plane form an equivalent ground.

[0008] Furthermore, the dielectric substrate is composed of a polyimide film (PI).

[0009] Furthermore, the patch antenna unit is made of liquid metal gallium indium alloy.

[0010] Furthermore, the patch antenna unit is formed by slotting a hexagonal metal patch, and an impedance matching network is formed by leading transmission lines out from the bottom of the hexagonal metal patch.

[0011] Furthermore, the feed microstrip line and the coplanar waveguide are used to form a central conductor strip on the upper part of the dielectric substrate, and square conductor planes are formed on both sides of the central conductor strip, with the central conductor strip and the square conductor strip surfaces located in the same plane.

[0012] Furthermore, the reflective ground plane is made of liquid metal.

[0013] Furthermore, the length of the reflective ground plane is the same as the length of the dielectric substrate, the width of the reflective ground plane is the same as the width of the dielectric substrate, and the thickness of the reflective ground plane is less than the thickness of the dielectric substrate but the same as the thickness of the patch antenna element.

[0014] The beneficial effects of this invention are:

[0015] (1) This invention overcomes the shortcomings of traditional antenna elements, such as poor conformality, difficulty in resisting mechanical deformation, and poor environmental adaptability. By using flexible materials and liquid metal for the patch antenna element and the reflective ground plane, this invention enables the antenna to bend and twist according to different environments while maintaining stable performance, thus exhibiting a certain degree of adaptability. This antenna device, when applied to the field of wireless power transmission, features high gain, low loss, and high acquisition efficiency, making it suitable for long-distance microwave wireless power transmission.

[0016] (2) This invention overcomes the disadvantages of large material loss and low energy harvesting and conversion efficiency of flexible antenna units, continuously optimizes the antenna unit structure, and adds a reflector plate compared with traditional coplanar waveguide antennas. This unit obtains higher gain and energy capture rate, and can realize wireless energy transmission over long distances.

[0017] (3) The present invention adopts a coplanar waveguide feeding method, which has the advantages of miniaturization and easy integration, and is suitable for electronic and electrical equipment in various occasions.

[0018] (4) In this invention, the reflective ground plane is printed from liquid metal and the dielectric substrate is made of flexible material. It can withstand a large degree of deformation, has excellent mechanical properties, good conformality and a certain degree of self-adaptability, and can conform well with the load. It can be stretched, bent, twisted and deformed while maintaining its stable performance. Attached Figure Description

[0019] Figure 1 This is a top view of the flexible antenna in this invention.

[0020] Figure 2This is a top view of the patch antenna unit in this embodiment.

[0021] Figure 3 This is a top view of the patch antenna element feed and waveguide in this embodiment.

[0022] Figure 4 This is a top view of the dielectric substrate in this embodiment.

[0023] Figure 5 This is a schematic diagram of the equivalent ground plane in this embodiment.

[0024] Figure 6 This is a cross-sectional view of the left side of the dielectric substrate in this embodiment.

[0025] Figure 7 This is a lower cross-sectional view of the dielectric substrate in this embodiment.

[0026] Figure 8 This is a schematic diagram showing the side length and angle of the hexagonal patch antenna element in this embodiment.

[0027] Figure 9 This is a schematic diagram showing the slot width and depth in the patch antenna unit of this embodiment.

[0028] Figure 10 This is a schematic diagram showing the dimensions and gaps of the coplanar waveguide feed line for the patch antenna in this embodiment.

[0029] Among them, 1-dielectric substrate, 2-patch antenna element, 3-feed microstrip line, 4-coplanar waveguide, 5-reflective ground plane, 6-feed interface. Detailed Implementation

[0030] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0031] Example

[0032] As described in the background art, to overcome the shortcomings of traditional antennas and enhance their application in different scenarios, this invention utilizes liquid metal printing technology and flexible materials to create a liquid metal antenna operating at 5.8 GHz for microwave wireless power transmission. This liquid metal patch antenna fully leverages the advantages of liquid gallium indium metal and flexible dielectric substrates, such as repairability, flexibility, reconfigurability, fatigue resistance, and corrosion resistance. It also combines the advantages of coplanar waveguide feeding, including low cost, high integration, simple manufacturing process, and a wide range of characteristic impedances. Applied to integrated small electronic devices, it enables electromagnetic wave reception while simultaneously miniaturizing, lightening, and integrating the device, and is suitable for long-distance wireless power transmission.

[0033] like Figure 1 As shown, the present invention provides a flexible antenna for wireless microwave power transmission, including a dielectric substrate 1, a patch antenna element 2, a feed microstrip line 3, a coplanar waveguide 4, and a reflective ground plane 5.

[0034] The patch antenna element 2, the feed microstrip line 3, and the coplanar waveguide 4 are all attached to the upper part of the dielectric substrate 1 and are in contact with the PI layer of the dielectric substrate 1. The reflective ground plane 5 is attached to the lower part of the dielectric substrate 1. The feed microstrip line 3 is led out from the lower part of the patch antenna element 2 and passes through the coplanar waveguide 4 to connect to an external power receiver. The feed microstrip line 3, the coplanar waveguide 4, and the reflective ground plane 5 form an equivalent ground.

[0035] In this embodiment, the flexible antenna comprises five parts: a dielectric substrate 1, a patch antenna element 2, a feed microstrip line 3, a coplanar waveguide 4, and a reflective ground plane 5. Based on the dielectric substrate 1, the patch antenna element 2, the feed microstrip line 3, and the coplanar waveguide 4 are tightly attached to the upper part of the dielectric substrate 1 and directly contact the PI layer of the dielectric substrate 1. The reflective ground plane 5 is tightly attached to the lower part of the dielectric substrate 1 and is equivalently grounded. The feed microstrip line 3 is led out from the lower part of the patch antenna element 2, passes through the coplanar waveguide 4, and connects to an external energy receiver, forming an equivalent ground with the coplanar waveguide 4 and the reflective ground plane 5.

[0036] In this embodiment, the dielectric substrate 1 is made of polyimide film PI, which is a flexible material with good mechanical properties, excellent thermal stability, and chemical corrosion resistance. It is usually orange-yellow, has a dielectric constant of 3.5 at microwave frequency, and a dielectric loss of only 0.002 to 0.007.

[0037] In this embodiment, the patch antenna unit 2 is made of liquid metal gallium indium alloy. The patch antenna unit 2 is formed by slotting a hexagonal metal patch, and an impedance matching network is formed by leading transmission lines out from the bottom of the hexagonal metal patch.

[0038] In this embodiment, a single patch antenna element is obtained by slotting a hexagonal metal patch, and a transmission line is led out from the bottom of the hexagonal element to form an impedance matching network.

[0039] In this embodiment, the feed microstrip line 3 and the coplanar waveguide 4 are used to form a central conductor strip on the upper part of the dielectric substrate 1, and square conductor planes are formed on both sides of the central conductor strip, with the central conductor strip and the square conductor strip surfaces located in the same plane.

[0040] In this embodiment, the fed microstrip line 3 and the coplanar waveguide 4 are fabricated by creating a central conductor strip on the front side of the dielectric substrate 1 (PI) and square conductor planes on both sides adjacent to the central conductor strip. Since the central conductor and the conductor planes are located in the same plane, it is convenient to connect components in parallel on the coplanar waveguide 4. The coplanar waveguide 4 has advantages such as small size, light weight, and planar structure, making it easy to achieve linear polarization, circular polarization, dual polarization, and multi-band operation. Compared with conventional microstrip transmission lines, the coplanar waveguide 4 has advantages such as ease of fabrication, ease of implementing series and parallel connections of passive and active devices in microwave circuits (without needing to drill holes in the substrate), and ease of increasing circuit density. Compared with the symmetrical coplanar waveguide 4, the asymmetrical coplanar waveguide offers greater flexibility when connected to devices at both ends.

[0041] In this embodiment, the reflective ground plane 5 is liquid metal, which is essentially a very thin layer of liquid metal that serves as an equivalent grounding layer. The length of the reflective ground plane 5 is the same as the length of the dielectric substrate 1, the width of the reflective ground plane 5 is the same as the width of the dielectric substrate 1, and the thickness of the reflective ground plane 5 is less than the thickness of the dielectric substrate 1 and the same as the thickness of the patch antenna element 2.

[0042] In this embodiment, as Figures 1-3 As shown, Figure 1 This is a top view of the schematic structure of the flexible antenna device. Figure 2 Figure 3 This is a top view of the patch antenna element 2, the feed microstrip line 3, and the coplanar waveguide 4. In this invention, a coplanar waveguide feeding method is employed, using the front coplanar waveguide 4 and the rear reflective ground plane 5 together as the equivalent ground plane of the device. This significantly improves the antenna's energy capture efficiency while achieving antenna miniaturization and increasing circuit density.

[0043] In this embodiment, as Figures 4 to 5 As shown, Figure 4 The structural dimensions of dielectric substrate 1 are indicated. Figure 4 In the diagram, u represents the x-axis, v represents the y-axis, and w represents the z-axis. The dielectric substrate is composed of a 40mm × 50mm polyimide film. Figure 5This is a schematic diagram of the grounding reflector 5 of the antenna device. The grounding reflector is constructed by printing 40mm × 50mm liquid metal onto the back of a dielectric substrate. In this invention, the dielectric substrate 1 uses a polyimide film, which is a deformable, high-mechanical-strength flexible material. The patch antenna element 2 is made of liquid metal gallium-indium alloy and is printed onto the upper surface of the dielectric substrate 1 using liquid metal printing technology. It is used to receive electromagnetic waves with a frequency of 5.8GHz in the environment.

[0044] In this embodiment, Figure 6 and Figure 7 These are cross-sectional side views of the antenna device from different directions. Figure 7 A schematic diagram of the antenna device's feed interface 6 can also be obtained. For example... Figure 6 and Figure 7 As shown, the cuboid-shaped feed microstrip line 3 passes close to the dielectric substrate 1, passing between the coplanar waveguides 4. Its upper end is directly connected to the patch antenna element 2, and it can be considered as an integral part of the patch antenna element 2. It is also made of liquid gallium indium alloy, and its thickness is much smaller than that of the dielectric substrate 1. When the feed interface 6 is connected to an external SMA interface, it is equivalently grounded together with the coplanar waveguide 4 and the grounding reflector 5. The energy of the patch antenna element 2 is transmitted to the feed interface 6 through the feed microstrip line 3. The microwave energy obtained by the feed interface 6 is transmitted to the next stage through cascading with the next stage structure (mostly a rectifier circuit).

[0045] In this embodiment, as Figures 8 to 10 As shown, Figures 8 to 10 This is a schematic diagram showing the structure and parameters of the patch antenna element, the feed transmission line, and the coplanar waveguide. Figure 8 In the middle, the patch antenna element has a hexagonal side length of 10.4mm and angles of 60° & 120°. Figure 9 In the patch antenna element, the slot depth is 9.9mm, the width is 0.2mm, and the slot spacing is 1.1mm. Figure 10In the antenna element 2, the coplanar waveguide is symmetrically composed of symmetrical 18.5mm × 14.1mm cuboids; the coplanar waveguide feed line is 15.2mm long and 2mm wide, with a 0.5mm gap between it and the coplanar waveguide grounding structure; the feed line forms a 150° angle with the patch element. In patch antenna element 2, the hexagonal patch resonates with electromagnetic waves of multiple frequencies in the environment, generating electric field energy, with the 5.8GHz electromagnetic wave energy being most concentrated in the middle section of patch antenna element 2. By slotting the hexagonal patch at the 5.8GHz electromagnetic wave energy resonance point, the antenna operating frequency is stabilized at 5.8GHz, while a transmission line is used to transmit energy. The reason for choosing to combine the coplanar waveguide 4 with the feed microstrip line 3 to form a coplanar waveguide structure and ground the feed interface 6 is to better obtain the antenna's linear polarization and reduce its size, thereby increasing circuit density. The use of the grounding reflector 5 is to achieve common grounding with the coplanar waveguide 4 while simultaneously achieving high antenna gain and reducing the antenna's electromagnetic wave energy transmittance, thus significantly improving the antenna's energy reception efficiency, which is a significant advantage over traditional coplanar waveguide patch antennas. Because the antenna material is liquid gallium indium alloy, and the antenna dielectric substrate 1 is made of polyimide film, this patch antenna has flexible and conformal characteristics, which is a significant advantage over traditional rigid material patch antennas. The high flexibility of the liquid metal and polyimide ensures that the antenna maintains stable performance under large deformations, while also adapting well to environmental changes and exhibiting good self-adaptability.

Claims

1. A flexible antenna for wireless microwave power transmission, characterized in that, It includes a dielectric substrate (1), a patch antenna element (2), a feed microstrip line (3), a coplanar waveguide (4), and a reflective ground plane (5); The patch antenna unit (2), the feed microstrip line (3), and the coplanar waveguide (4) are closely attached to the upper part of the dielectric substrate (1) and in contact with the PI layer of the dielectric substrate (1). The reflective ground plane (5) is closely attached to the lower part of the dielectric substrate (1). The feed microstrip line (3) is led out from the lower part of the patch antenna unit (2) and passes through the coplanar waveguide (4) to connect to an external energy receiver. The feed microstrip line (3), the coplanar waveguide (4), and the reflective ground plane (5) form an equivalent ground. The feed microstrip line (3) and the coplanar waveguide (4) form a central conductor strip on the upper part of the dielectric substrate (1), and square conductor planes are formed on both sides of the central conductor strip, and the central conductor strip and the square conductor strip are located in the same plane. The patch antenna unit (2) is formed by slotting a hexagonal metal patch, and an impedance matching network is formed by leading a transmission line out from the bottom of the hexagonal metal patch; the antenna operating frequency is stabilized at 5.8GHz by slotting the hexagonal metal patch at the 5.8GHz electromagnetic wave energy resonance point, and the energy is transmitted by the transmission line; the coplanar waveguide (4) and the feed microstrip line (3) are combined to form a coplanar waveguide structure so that the feed interface (6) is grounded, thereby obtaining the linear polarization of the antenna and reducing the size of the antenna; the grounding reflector (5) is used to achieve common grounding with the coplanar waveguide (4) while achieving high antenna gain and reducing the electromagnetic wave energy transmittance of the antenna.

2. The flexible antenna for wireless microwave power transmission according to claim 1, characterized in that, The dielectric substrate (1) is composed of a polyimide film (PI).

3. The flexible antenna for wireless microwave power transmission according to claim 1, characterized in that, The patch antenna unit (2) is made of liquid metal gallium indium alloy.

4. The flexible antenna for wireless microwave power transmission according to claim 1, characterized in that, The reflective ground plane (5) is liquid metal.

5. The flexible antenna for wireless microwave power transmission according to claim 4, characterized in that, The length of the reflective ground plane (5) is the same as the length of the dielectric substrate (1), the width of the reflective ground plane (5) is the same as the width of the dielectric substrate (1), the thickness of the reflective ground plane (5) is less than the thickness of the dielectric substrate (1), and the same as the thickness of the patch antenna unit (2).

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