Tight coupling ultra-wideband antenna applied to wireless energy transmission

Abstract

The invention belongs to but not limited to the technical field of microwave antennas, and discloses a tight coupling ultra-wideband antenna for wireless energy transmission and application thereof. The tight coupling antenna unit is used for improving the bandwidth performance of the antenna; the RFSS is used for absorbing reflected waves from the ground plane to eliminate short-circuit effect points so as to realize ultra-wideband antenna design; the wide-angle matching layer is used for improving the radiation efficiency of the antenna; the tapered line structure is used for realizing conversion between unbalance and balance and is also used for impedance matching; and the power division structure is used for combining the plurality of tightly coupled antenna units into one subunit and completing impedance conversion at the same time. By adding the resistive frequency selective surface (RFSS), the short-circuit effect is eliminated, and the ultra-wideband low-profile performance is realized; the RFSS thin film is vertically integrated on the dielectric substrate, and is suitable for flexible design.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave antennas, and in particular relates to a tightly coupled ultra-wideband antenna used for wireless energy transmission. Background Art

[0002] With the rapid development of wearable devices, the Internet of Things (IoT) and implantable medical devices, the demand for flexible electronic devices continues to increase. The limitations of traditional rigid antennas in these applications are becoming more and more obvious, especially in scenarios that require bending, stretching or deformation. In order to meet these needs, flexible antennas have emerged and have gradually become an important research direction in wireless energy transmission technology. Flexible antennas can maintain good electrical properties under various complex deformation conditions and adapt to different wearing or installation environments. In wireless energy transmission applications, broadband flexible antennas are particularly critical. They not only need to transmit energy over a wide frequency range, but also must maintain efficient energy transmission performance when bent, twisted or even folded. The broadband characteristics ensure that the antenna can adapt to different operating frequency bands and improve the compatibility and adaptability of the system, while the flexible characteristics give the antenna a wider range of application scenarios, such as wearable devices, flexible electronics and implantable medical devices. Therefore, the design of broadband flexible antennas is very necessary.

[0003] At present, most broadband antennas used for wireless energy transmission cannot meet the requirements of broadband and flexibility. In the document "AD Johnson, J. Zhong, SB Venkatakrishnan, EA Alwan and JLVolakis, "Phased array with low-angle scanning and 46:1 bandwidth," in IEEE Trans. Antennas Propag., vol. 68, no. 12, pp. 7833-7841, Dec. 2020.", foreign scholars AD Johnson et al. proposed an ultra-wideband tightly coupled antenna array operating in the frequency range of 0.13-6 GHz, but the antenna uses a resistive frequency selective surface (RFSS) placed parallel to the ground, which cannot be flexibly bent, and the antenna structure is not purely vertically placed, and the structure is complex; in the document "JX Sun, MZ Chen and YJ Cheng," Single-PCB Fabricated, Ultrawideband, and Wide-Scanning Phased Array Antenna With Vertically Integrated Resistive Frequency-Selective Surface," in IEEE Transactions on Antennas and Propagation, vol.72, no.3, pp.2411-2422, March 2024." Sun Jianxu and others from the University of Electronic Science and Technology of China designed an ultra-wideband tightly coupled antenna with a vertically integrated resistive frequency-selective surface. The antenna operates in the frequency range of 0.8-12 GHz, but uses a lumped resistor, which not only requires additional welding, but also cannot be used for flexible bending.

[0004] In view of the above analysis, the technical problems that need to be urgently solved in the prior art are: it is impossible to achieve broadband operation and flexible bending, and the structure is complex. Therefore, it is necessary to design a new tightly coupled ultra-wideband antenna for wireless energy transmission. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes a tightly coupled ultra-wideband antenna for wireless energy transmission, with the aim of achieving ultra-wideband coverage and high gain while realizing a bendable antenna design to meet the needs of wireless energy transmission applications.

[0006] The design concept of the present invention is to eliminate the short-circuit effect by adding a resistive frequency selective surface (RFSS) to achieve ultra-wideband low-profile performance; the RFSS film is used and vertically integrated on a dielectric substrate, which is suitable for flexible design.

[0007] The present invention is implemented as follows: a tightly coupled ultra-wideband antenna for wireless energy transmission, the tightly coupled ultra-wideband antenna comprising:

[0008] Tightly coupled antenna units are used to achieve the broadband performance of the antenna;

[0009] RFSS, used to absorb reflected waves from the ground plane to eliminate short-circuit effect points to achieve ultra-wideband antenna design;

[0010] Wide-angle matching layer to improve antenna radiation efficiency;

[0011] Gradient line structure, used to achieve the conversion between unbalanced and balanced, and also used for impedance matching;

[0012] The power division structure is used to combine multiple tightly coupled antenna units into one sub-unit and complete impedance transformation at the same time.

[0013] Furthermore, the tightly coupled ultra-wideband antenna includes two layers of dielectric substrate and three layers of metal. The main part of the tightly coupled antenna unit is located in the middle metal layer. In order to increase the coupling amount, metal patches are placed on the top and bottom metal layers respectively, and the tightly coupled antenna unit is placed below the wide-angle matching layer and above the RFSS; the RFSS is located on the bottom metal layer; the wide-angle matching layer is located in the middle metal layer; the gradient line structure is located in the middle metal layer; and the power division structure is located on the top metal layer.

[0014] Furthermore, the tightly coupled antenna unit is generally designed as a dipole;

[0015] Further, the RFSS may be designed by using resistive thin film or lumped resistance welding;

[0016] Furthermore, the wide-angle matching layer may be designed as a rectangular patch or a metal strip;

[0017] Furthermore, the gradient line structure can be designed using a linear, exponential or other form of gradient line structure;

[0018] Furthermore, the power division structure is generally designed using a T-junction.

[0019] Another object of the present invention is to provide a method for preparing a tightly coupled ultra-wideband antenna for wireless energy transmission, comprising:

[0020] (1) The tightly coupled antenna unit is set on the middle metal layer, and metal patches are placed on the top and bottom metal layers respectively. The tightly coupled antenna unit is placed below the wide-angle matching layer and above the RFSS.

[0021] (2) The RFSS is set on the metal bottom layer; the wide-angle matching layer is set on the middle metal layer; the gradient line structure is set on the middle metal layer; and the power division structure is set on the metal top layer.

[0022] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0023] First, the present invention eliminates the short-circuit effect by adding a resistive frequency selective surface (RFSS) to achieve ultra-wideband low-profile performance; the present invention adopts an RFSS film and vertically integrates it on a dielectric substrate, which is suitable for flexible design; the present invention does not use a lumped resistor for RFSS design to prevent the lumped resistor from falling off during bending; the antenna proposed by the present invention is placed vertically, there is no structure parallel to the ground, and the structure is simple.

[0024] Second, the expected benefits and commercial value after the transformation of the technical solution of the present invention are as follows: the tightly coupled ultra-wideband antenna proposed in the present invention adopts RFSS film and places it vertically, which is simpler in structure than the traditional wideband tightly coupled antenna, can be flexibly bent, and has a wider range of applications.

[0025] The technical solution of the present invention solves a technical problem that people have been eager to solve but have never been able to solve successfully: the tightly coupled ultra-wideband antenna proposed by the present invention can not only operate in the frequency range of 1-10GHz, but also has the characteristics of flexible bending. This design successfully combines ultra-wideband performance with flexible structure, breaking through the limitations of traditional antennas in broadband response and flexible applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a front view of a two-in-one subunit of a tightly coupled antenna provided in an embodiment of the present invention.

[0027] Figure 2 A schematic rear view of a two-in-one tightly coupled antenna subunit provided in an embodiment of the present invention.

[0028] Figure 3 A flow chart of a method for preparing a tightly coupled ultra-wideband antenna for wireless energy transmission provided in an embodiment.

[0029] Figure 4 A diagram showing simulation results of the standing wave ratio (VSWR) of the tightly coupled antenna subunit provided in the embodiment.

[0030] Figure 5A diagram showing the simulation results of the radiation efficiency and overall efficiency of the tightly coupled antenna subunits provided in the embodiment.

[0031] In the figure: 1. Wide-angle matching layer, 2. RFSS film, 3. Gradient line structure, 4. Tightly coupled dipole antenna unit, 5. Power division structure. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] The embodiment of the present invention provides a tightly coupled ultra-wideband antenna for wireless energy transmission, wherein the tightly coupled ultra-wideband antenna comprises: a tightly coupled antenna unit, an RFSS, a wide-angle matching layer, a gradient line structure, and a power division structure.

[0034] First, by adopting a tight coupling design, the bandwidth performance of the antenna is significantly improved. This design allows the antenna to work effectively in a wider frequency range, while reducing the problem of bandwidth narrowing, ensuring the antenna's efficient transmission capability in the ultra-wideband frequency range.

[0035] Secondly, RFSS (reflected wave absorbing structure) plays a key role. It eliminates the point where the short-circuit effect occurs by absorbing the reflected waves from the ground plane. This design ensures that the radiation characteristics of the antenna are not disturbed by the reflected waves, further improving the overall performance of the antenna, and enabling the antenna to maintain a stable working state over a wider frequency range. If RFSS uses resistive film, it will have good flexible bending properties and will be suitable for a wider range of application scenarios.

[0036] Then, the wide-angle matching layer improves the antenna's radiation efficiency by optimizing the match between the antenna and free space. The design of the wide-angle matching layer enables the antenna to radiate effectively over a wider range of incident angles, thereby improving the efficiency of wireless energy transmission. This layer not only improves the antenna's directivity and radiation efficiency, but also allows the antenna to maintain consistent performance at different angles.

[0037] Finally, the gradient line structure and the power splitter structure jointly complete the impedance matching and signal distribution tasks of the antenna. The gradient line structure is responsible for realizing the conversion between imbalance and balance, and through the gradually changing impedance design, a smooth transition from 50Ω to 120Ω is achieved without the need for additional matching circuits. The power splitter structure combines two tightly coupled antenna units into one sub-unit and completes the impedance transformation at the same time, so that the antenna can naturally achieve impedance matching when working in a wide frequency band of 1-10GHz, thereby ensuring stable signal transmission and efficient operation of the antenna.

[0038] Figure 1 and Figure 2 It is the front view and rear view of the overall structure of the embodiment of the present invention. The tightly coupled antenna unit of the embodiment of the present invention adopts a dipole unit; the RFSS is made of resistive thin film material; the wide-angle matching layer adopts a rectangular metal patch; the gradient line structure adopts a linear gradient structure; the power division structure adopts a T-junction, and the input port ① impedance is 50Ω.

[0039] The embodiment of the present invention includes two layers of dielectric substrates and three layers of metal, and different colors represent different metal layers. The two layers of dielectric substrates are both made of Rogers RO3003, with a dielectric constant of 3 and a substrate thickness of 0.254 mm.

[0040] like Figure 3 As shown, the method for preparing a tightly coupled ultra-wideband antenna for wireless energy transmission provided by an embodiment of the present invention includes:

[0041] (1) The tightly coupled antenna unit is set on the middle metal layer, and metal patches are placed on the top and bottom metal layers respectively. The tightly coupled antenna unit is placed below the wide-angle matching layer and above the RFSS film.

[0042] (2) The RFSS film is set on the metal bottom layer; the wide-angle matching layer is set on the middle metal layer; the gradient line structure is set on the middle metal layer; and the power division structure is set on the metal top layer.

[0043] Figure 4 It is shown that when the signal is input from port ① of the power division structure, the standing wave ratio of the tightly coupled antenna subunit is less than 3 in the frequency range of 1-10 GHz, indicating that the present invention realizes the design of ultra-wideband antenna.

[0044] Figure 5 The radiation efficiency and overall efficiency of the tightly coupled antenna subunit are demonstrated when the signal is input from port ① of the power division structure. The radiation efficiency is greater than 51% in the frequency range of 1-10 GHz, and the overall efficiency is greater than 35% in the frequency range of 1-10 GHz, indicating that the present invention can achieve ultra-wideband while also receiving signals more efficiently, which is beneficial to energy reception.

[0045] Example 1: Preparation and testing of tightly coupled ultra-wideband antenna

[0046] 1. Preparation of antenna structure:

[0047] Select the appropriate antenna substrate material, first make a tightly coupled antenna unit on the middle metal layer, and place metal patches on the top and bottom metal layers. The tightly coupled antenna unit is set below the wide-angle matching layer and above the RFSS film to ensure that the design of the tightly coupled antenna structure can achieve wideband transmission.

[0048] The RFSS film is placed on the metal bottom layer to reduce the antenna's surface wave loss and multipath effect, optimizing the antenna's efficiency. The wide-angle matching layer is placed on the middle metal layer to improve the matching performance, allowing the antenna to maintain good impedance matching over a wider frequency band.

[0049] A gradient line structure is set on the middle metal layer to optimize the impedance change of the signal transmission path. The power division structure is set on the top metal layer to distribute the input signal to each tightly coupled antenna unit.

[0050] 2. Test results:

[0051] The signal is input through port ① of the power splitter structure to perform a VSWR test. The test results show that within the frequency range of 1-10GHz, the VSWR of the antenna is less than 3, indicating that the antenna has good matching performance within this frequency band.

[0052] The radiation efficiency of the antenna was tested and it was found that the radiation efficiency of the antenna in the range of 1-10GHz was greater than 51%, and the overall efficiency was greater than 35%. These test results show that the antenna not only achieves ultra-wideband transmission, but also has a high energy receiving efficiency, which is suitable for wireless power transmission applications.

[0053] Example 2: Preparation of tightly coupled ultra-wideband antenna with optimized gradient line structure

[0054] 1. Optimization and preparation of antenna structure:

[0055] A gradient line structure is designed on the metal intermediate layer so that the impedance change can be effectively controlled and the reflection loss can be reduced during the signal transmission from the power division structure to the tightly coupled antenna unit.

[0056] Select low-loss RFSS film materials and place them on the metal bottom layer to ensure that the film can suppress surface waves and improve the radiation efficiency of the antenna. Metal patches are placed on the top and bottom metal layers to further enhance the antenna's structural stability and broadband transmission performance.

[0057] A wide-angle matching layer is placed above the antenna unit to enhance the broadband matching characteristics of the antenna, enabling it to cover a wider frequency band.

[0058] 2. Performance testing and result analysis:

[0059] The standing wave ratio of the input signal of the antenna was tested, and it was found that the standing wave ratio was maintained at a level less than 3 in the frequency range of 1-10GHz, proving that the broadband matching characteristics of the antenna have been effectively improved.

[0060] By testing the radiation efficiency and overall efficiency of the antenna, it was found that the radiation efficiency remained above 53% within the frequency range, and the overall efficiency was increased to above 37%. These results show that the antenna's signal transmission is more efficient and can achieve a higher wireless energy transmission effect.

[0061] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A tightly coupled ultra-wideband antenna for wireless energy transmission, characterized in that: The tightly coupled ultra-wideband antenna comprises: Tightly coupled antenna units are used to improve the bandwidth performance of the antenna; RFSS, used to absorb reflected waves from the ground plane to eliminate short-circuit effect points to achieve ultra-wideband antenna design; Wide-angle matching layer to improve antenna radiation efficiency; Gradient line structure, used to achieve the conversion between unbalanced and balanced, and also used for impedance matching; The power division structure is used to combine multiple tightly coupled antenna units into one sub-unit and complete impedance transformation at the same time.

2. The tightly coupled ultra-wideband antenna for wireless energy transmission according to claim 1, characterized in that: The tightly coupled ultra-wideband antenna comprises two layers of dielectric substrates and three layers of metal; the main part of the tightly coupled antenna unit is located in the middle metal layer, metal patches are placed on the top and bottom metal layers respectively, and the tightly coupled antenna unit is placed below the wide-angle matching layer and above the RFSS; The RFSS is located at the bottom metal layer; the wide-angle matching layer is located at the middle metal layer; the gradient line structure is located at the middle metal layer; and the power division structure is located at the top metal layer.

3. The tightly coupled ultra-wideband antenna for wireless energy transmission according to claim 1, characterized in that: The tightly coupled antenna unit adopts a dipole.

4. The tightly coupled ultra-wideband antenna for wireless energy transmission according to claim 1, characterized in that: The RFSS is welded using resistive film or lumped resistance.

5. The tightly coupled ultra-wideband antenna for wireless energy transmission according to claim 1, characterized in that: The wide-angle matching layer is in the form of a rectangular patch or a metal strip.

6. The tightly coupled ultra-wideband antenna for wireless energy transmission according to claim 1, characterized in that: The gradient line structure adopts a linear gradient line structure or an exponential gradient line structure.

7. The tightly coupled ultra-wideband antenna for wireless energy transmission according to claim 1, characterized in that: The power division structure adopts a T-shaped structure.

8. A method for preparing a tightly coupled ultra-wideband antenna for wireless energy transmission according to any one of claims 1 to 7, comprising: (1) The tightly coupled antenna unit is set on the middle metal layer, and metal patches are placed on the top and bottom metal layers respectively. The tightly coupled antenna unit is placed below the wide-angle matching layer and above the RFSS film. (2) The RFSS film is set on the metal bottom layer; the wide-angle matching layer is set on the middle metal layer; the gradient line structure is set on the middle metal layer; and the power division structure is set on the metal top layer.

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