Bandwidth improving method based on thin-film small antenna, antenna and electronic equipment

Abstract

The invention discloses a bandwidth improving method based on a thin-film small antenna, an antenna and electronic equipment, and the method comprises the steps: carrying out the model construction under the condition that the area of an original thin-film small antenna meets the impedance matching requirement, obtaining an original thin-film small antenna model, introducing a penalty function, and multiplying the material density with a penalty material volume factor, and taking the average material volume factor as a constraint condition, carrying out topological optimization on the original thin film small antenna by using a variable density method of which the difference value type is SIMP, carrying out multiple times of iterative calculation in topological optimization to adjust material distribution, and taking the maximum magnetic layer average stress as a target function until a preset number of iterations is reached to obtain the thin film small antenna after iteration. According to the invention, the thickness and the area of the original thin-film small antenna are not changed and guaranteed, the shape of the original thin-film antenna is subjected to topological optimization by taking the optimal bandwidth as the target to obtain the improved thin-film small antenna, the antenna processing complexity can be reduced, the impedance bandwidth of the antenna is effectively improved, and thus the requirement of a system for the antenna bandwidth is met.

Description

Technical Field

[0001] The present application relates to the technical field of thin-film small antennas, and in particular to a bandwidth enhancement method based on thin-film small antennas, an antenna, and an electronic device. Background Art

[0002] Traditional antenna design is based on the quarter-wavelength resonance theory, which makes the miniaturization of antennas extremely challenging. Even after miniaturization, the size of a typical electrical antenna is usually larger than one-tenth of the wavelength of the electromagnetic wave at its operating frequency. With the in-depth study of the radiation and reception mechanism of electromagnetic waves, a small thin-film antenna that uses a new radiation principle has emerged in recent years.

[0003] This new type of thin film small antenna is mainly composed of a heterogeneous structure composed of piezoelectric material and ferromagnetic material. When an external voltage is applied, the piezoelectric layer will generate acoustic vibrations, which are transmitted to the ferromagnetic layer through the piezoelectric / ferromagnetic interface, thereby stimulating the latter to generate time-varying magnetic currents, thereby realizing the emission of electromagnetic waves; on the contrary, when the antenna receives an external electromagnetic wave signal, the ferromagnetic layer will sense the change in the magnetic field and convert it into a voltage output on the piezoelectric layer. Unlike traditional antennas that rely on the resonant frequency of electromagnetic waves to work, this new type of thin film small antenna uses the mechanical resonance characteristics of acoustic waves to complete energy conversion. Given that the speed of acoustic waves is much lower than that of electromagnetic waves (about 4-5 orders of magnitude lower), under the same operating frequency conditions, this new type of antenna based on acoustic wave resonance can significantly reduce the physical size. While maintaining the original performance, its volume can be reduced by about 10 to 100 times compared with traditional metal antennas. Although the above-mentioned thin film small antenna performs well in size reduction, it also has the problem of extremely narrow bandwidth.

[0004] In order to overcome this limitation, the prior art proposes to enhance the antenna bandwidth by introducing a Bragg reflection layer. However, this method is not only costly, but also has a high implementation process complexity, which greatly limits its practicality. Therefore, how to develop a technical solution that can maintain the advantage of small size while effectively broadening the operating frequency band has become one of the key issues that need to be solved urgently. Summary of the invention

[0005] The purpose of this application is to provide a bandwidth improvement method, antenna and electronic device based on a small thin film antenna in order to overcome the existing technical defects. The shape of the original thin film antenna is topologically optimized with the optimal bandwidth as the goal to obtain an improved small thin film antenna, which can reduce the complexity of antenna processing and effectively improve the impedance bandwidth of the antenna, thereby meeting the system's requirements for antenna bandwidth.

[0006] The purpose of this application is achieved through the following technical solutions:

[0007] In a first aspect, the present application proposes a method for improving bandwidth based on a thin film small antenna, the method comprising:

[0008] The model is constructed under the condition that the area of ​​the original thin film small antenna meets the impedance matching requirement to obtain the original thin film small antenna model;

[0009] A penalty function is introduced into the original thin film small antenna model, and then the material density is multiplied by the penalty material volume factor. The average material volume factor is used as a constraint condition, and the variable density method with the difference type of SIMP is used to perform topology optimization on the original thin film small antenna.

[0010] In the topology optimization, multiple iterative calculations are performed to adjust the material distribution, and the maximum average stress of the magnetic layer is used as the objective function until the preset number of iterations is reached to obtain the iterative thin film small antenna.

[0011] In a possible implementation, during the topology optimization process, it is ensured that the thickness and area of ​​the iterative small thin-film antenna are consistent with those of the original small thin-film antenna.

[0012] In a possible implementation, smoothing is performed after each iteration.

[0013] In a possible implementation, the mathematical expression of topology optimization is:

[0014] Find:x={x1,x2,...,x n} T

[0015] Maximum:

[0016] Subject to:

[0017] 0 <x min <x i ≤1;

[0018] Where x is the target variable, V is the design volume, T is the average stress of the magnetosphere, σ(x) is the magnetosphere stress at the target variable, V' is the optimized design volume, and x i is the material density within each unit cell, V i For the corresponding x i design volume.

[0019] In one possible implementation, COMSOL Multiphysics is used for model building.

[0020] In a possible implementation manner, the iterative small film antenna is simulated to obtain the S11 curve of the iterative small film antenna.

[0021] In a second aspect, the present application further proposes an antenna, which is manufactured using the bandwidth enhancement method of the first aspect.

[0022] In a third aspect, the present application further proposes an electronic device, comprising the antenna of the second aspect.

[0023] The above-mentioned main scheme of the present application and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection in the present application; and in the present application, (non-conflicting options) options and other options can also be freely combined. After understanding the scheme of the present application, those skilled in the art can understand that there are multiple combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present application, and they are not exhaustively listed here.

[0024] The present application discloses a bandwidth enhancement method, antenna and electronic device based on a thin film small antenna. The model is constructed to obtain the original thin film small antenna model while ensuring that the area of ​​the original thin film small antenna meets the impedance matching requirements. After introducing the penalty function, the material density is multiplied by the penalty material volume factor, and the average material volume factor is used as a constraint condition. The original thin film small antenna is topologically optimized using the variable density method with a difference type of SIMP. Multiple iterative calculations are performed in the topology optimization to adjust the material distribution, and the maximum magnetic layer average stress is used as the objective function until the preset number of iterations is reached to obtain the iterated thin film small antenna. Without changing the thickness and area of ​​the original thin film small antenna, the shape of the original thin film antenna is topologically optimized with the optimal bandwidth as the goal to obtain an improved thin film small antenna, which can reduce the complexity of antenna processing and effectively improve the impedance bandwidth of the antenna, thereby meeting the system's demand for antenna bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic flow chart of a bandwidth enhancement method based on a small thin-film antenna proposed in an embodiment of the present application is shown.

[0027] Figure 2 The original thin film small antenna model shown in the embodiment of the present application is shown.

[0028] Figure 3 The S11 curve of the iterative small film antenna proposed in the embodiment of the present application is shown.

[0029] Figure 4 A topology optimization iterative process diagram proposed in an embodiment of the present application is shown.

[0030] Figure 5 The small film antenna proposed in the embodiment of the present application is shown after 100 iterations.

[0031] Figure 6 The S11 curve of the improved small thin film antenna proposed in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0034] In the prior art, the new thin-film small antenna is mainly composed of a heterostructure composed of piezoelectric materials and ferromagnetic materials. When an external voltage is applied, the piezoelectric layer will generate acoustic vibrations, which are transmitted to the ferromagnetic layer through the piezoelectric / ferromagnetic interface, thereby stimulating the latter to generate time-varying magnetic currents, thereby realizing the emission of electromagnetic waves; conversely, when the antenna receives an external electromagnetic wave signal, the ferromagnetic layer will sense the change in the magnetic field and convert it into a voltage output on the piezoelectric layer.

[0035] Unlike traditional antennas that rely on the resonant frequency of electromagnetic waves to work, this new type of thin-film small antenna uses the mechanical resonance characteristics of sound waves to complete energy conversion. Given that the speed of sound waves is much lower than that of electromagnetic waves (about 4-5 orders of magnitude lower), this new type of antenna based on sound wave resonance can significantly reduce the physical size under the same operating frequency conditions. While maintaining the original performance, its volume can be reduced by about 10 to 100 times compared to traditional metal antennas. Although the above-mentioned thin-film small antenna performs well in reducing size, it also has the problem of extremely narrow bandwidth.

[0036] In order to overcome this limitation, the prior art proposes to enhance the antenna bandwidth by introducing a Bragg reflection layer. However, this method is not only costly, but also has a high implementation process complexity, which greatly limits its practicality. Therefore, how to develop a technical solution that can maintain the advantage of small size while effectively broadening the operating frequency band has become one of the key issues that need to be solved urgently.

[0037] Therefore, in order to solve the problem of narrow bandwidth of existing thin-film antennas, reduce the complexity of antenna processing, and effectively improve the impedance bandwidth of the antenna, thereby meeting the system's demand for antenna bandwidth, the embodiment of the present application proposes a bandwidth enhancement method, antenna and electronic device based on a small thin-film antenna, and improves the design of the small thin-film antenna through topology optimization technology, thereby significantly improving its bandwidth performance, which is explained below.

[0038] Please refer to Figure 1 , Figure 1 A schematic flow chart of a method for improving bandwidth based on a thin film small antenna proposed in an embodiment of the present application is shown, including:

[0039] Step S1, constructing a model to obtain an original thin film small antenna model while ensuring that the area of ​​the original thin film small antenna meets the impedance matching requirement;

[0040] Step S2, introducing a penalty function into the original thin film small antenna model, then multiplying the material density by the penalty material volume factor, taking the average material volume factor as a constraint condition, and using a variable density method with a difference type of SIMP to perform topology optimization on the original thin film small antenna;

[0041] Step S3, performing multiple iterative calculations in the topology optimization to adjust the material distribution, taking the maximum magnetic layer average stress as the objective function, until a preset number of iterations is reached to obtain an iterated thin film small antenna.

[0042] SIMP (Solid Isotropic Material with Penalization) variable density method is used for topology optimization. A penalty function is introduced to multiply the material density by the penalty material volume factor, and the average material volume factor is used as a constraint to ensure that the optimized structure does not have an intermediate density value and avoid gray areas. During the optimization process, the thickness and area of ​​the final film antenna must be consistent with the original antenna. The initial shape is a small circular film antenna. Through multiple iterative calculations, the material distribution is adjusted until the preset maximum number of iterations is reached or other stop conditions are met.

[0043] Specifically, the maximum average stress of the magnetic layer is taken as the optimization target, so that the maximum average stress of the magnetic layer of the thin film antenna is minimized under the working state. The variable density method is adopted, especially the SIMP model. By introducing the penalty factor dtopo1.theta_p and multiplying it with the material density, the solution can be pushed to a discrete value between 0 and 1, so as to be closer to the state of whether the material exists or not under actual manufacturing conditions. In order to ensure that the optimized small antenna can still meet the area invariance, the volume constraint is set. Although the shape of the optimized structure may change, the total volume (or the area covered) remains constant, which is the same as the original circular thin film small antenna. The thin film small antenna is composed of two materials: terbium dysprosium iron and aluminum nitride, and the thickness of each material is 20 microns. When an electric field is applied, some areas will undergo displacement changes of about 10 nanometers.

[0044] The entire optimization process is as follows: the initial settings include defining the problem boundary, selecting appropriate parameters, etc. Then, an iterative solution is performed, and the material distribution within each unit is adjusted in each iteration to gradually approach the optimal solution. The iteration is stopped after reaching the predetermined number of times or reaching the convergence standard. Finally, the obtained design is smoothed to remove unnecessary details or noise. After completing the above steps, finite element analysis is also needed to evaluate the performance of the new design, such as checking the change in the reflection coefficient, to verify whether the modifications have indeed improved the performance of the original design.

[0045] Model building using COMSOL Multiphysics. Figure 2 The original thin film small antenna model shown in the embodiment of the present application is shown. For example, the magnetostrictive material in the thin film small antenna is terbium dysprosium iron, and the piezoelectric material is aluminum nitride; the radius of the thin film small antenna disk is 450um, and the area is about 0.6362mm 2 The thickness of magnetostrictive material and piezoelectric material are both 20um, and the total thickness is 40um.

[0046] During the topology optimization process, it is ensured that the thickness and area of ​​the iterative small film antenna are consistent with the original small film antenna.

[0047] Smoothing is performed after each iteration to remove non-ideal features such as jagged boundaries.

[0048] The mathematical expression of topology optimization is:

[0049]

[0050] Where x is the target variable, V is the design volume, T is the average stress of the magnetosphere, σ(x) is the magnetosphere stress at the target variable, V' is the optimized design volume, and xi is the material density within each unit cell, V i For the corresponding x i design volume.

[0051] σ(x) is the stress distribution of the material at different positions, which can be obtained through simulation and reflects the stress of the material at different densities. By integrating the entire volume, the total magnetic layer stress can be obtained, and the integral is actually a weighted sum of the stress of all cells. V = 0.6V' ensures that the optimized design volume is 60% of the original volume. If the total area needs to remain unchanged, this ratio can be adjusted to 100%. 0 <x min <x i ≤1 ensures that the material density within each cell is within a reasonable range. This means that the material density cannot be zero (i.e. no gaps) nor exceed a fully filled state.

[0052] Figure 4 The topology optimization iterative process diagram proposed in the embodiment of the present application is shown, the horizontal axis represents the number of iterations, and the curve in the chart represents the change of the parameter value as the number of iterations increases. The curve starts from the lower left corner, gradually rises, and finally stabilizes. The four illustrations correspond to different numbers of iterations and parameter values. When the number of iterations is 10 times, the shape is a ring structure, in which the thickness of the ring structure remains unchanged at 40um, the outer diameter of the ring structure is 650um, and the inner diameter is 469um, then the area is the same as the original thin film small antenna model to ensure impedance matching.

[0053] Figure 5 The diagram shows a small thin film antenna after 100 iterations proposed in an embodiment of the present application. The area of ​​the small thin film antenna of this shape is the same as the area of ​​the initial small thin film antenna, and the thicknesses of terbium dysprosium iron and aluminum nitride are both 20um. The curve after 100 iterations tends to be nearly flat.

[0054] The iterative small film antenna is simulated to obtain the S11 curve of the iterative small film antenna to verify its bandwidth performance. Figure 3 The S11 curve of the iterative small thin film antenna proposed in the embodiment of the present application is shown, where the horizontal axis represents frequency (unit: MHz), the vertical axis represents S parameter (dB), the peak position is at 172.0772197 MHz, and the peak S parameter value is about -10dB. It can be seen that the operating frequency of the iterative small thin film antenna is 172 MHz, and the -10dB bandwidth is 0.077 MHz, indicating that the original antenna has achieved impedance matching, and its thickness and area need to be kept unchanged in the subsequent topology optimization process.

[0055] Figure 6The S11 curve of the improved thin film small antenna proposed in the embodiment of the present application is shown. The improved operating frequency is 172 MHz, and the -10dB bandwidth is 0.128 MHz. Compared with the S11 curve of the original thin film small antenna, the bandwidth of the improved thin film small antenna is further improved.

[0056] Therefore, the embodiment of the present application can maintain the thickness and area of ​​the original thin-film small antenna, and perform topological optimization on the shape of the original thin-film antenna with the optimal bandwidth as the goal to obtain an improved thin-film small antenna, which can reduce the complexity of antenna processing and effectively improve the impedance bandwidth of the antenna, thereby meeting the system's requirements for antenna bandwidth.

[0057] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0058] First, through topology optimization, the bandwidth of the small thin-film antenna has been significantly improved, by about 66%.

[0059] Second, the SIMP variable density method is used for topology optimization, combined with advanced simulation technology, to make the design process more scientific, reasonable and easy to implement.

[0060] Third, the optimization results are verified through simulation to ensure the feasibility and superiority of the new structure in practical applications.

[0061] The specific type of the antenna according to the bandwidth improvement method proposed in the embodiment of the present application is not particularly limited. For example, a 5G antenna, an NFC antenna, etc., those skilled in the art can make corresponding selections based on the actual use requirements of the antenna, which will not be repeated here.

[0062] The electronic device with an antenna proposed in the embodiment of the present application includes an antenna made by the above-mentioned embodiment. The specific type of the electronic device is not particularly limited, such as mobile phones, tablet computers, smart watches, etc. Those skilled in the art can make corresponding choices according to the specific use of the electronic device, which will not be repeated here. It should be noted that in addition to the above-mentioned antenna, the electronic device also includes other necessary components and structures. Taking a mobile phone as an example, such as a display device, a processor, a memory, a battery, a circuit board, a camera, etc., those skilled in the art can design and supplement accordingly according to the specific type of the electronic device, which will not be repeated here.

[0063] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A bandwidth enhancement method based on a thin film small antenna, characterized in that: The method comprises: The model is constructed under the condition that the area of ​​the original thin film small antenna meets the impedance matching requirement to obtain the original thin film small antenna model; A penalty function is introduced into the original thin film small antenna model, and then the material density is multiplied by the penalty material volume factor. The average material volume factor is used as a constraint condition, and the variable density method with the difference type of SIMP is used to perform topology optimization on the original thin film small antenna. In the topology optimization, multiple iterative calculations are performed to adjust the material distribution, and the maximum average stress of the magnetic layer is used as the objective function until the preset number of iterations is reached to obtain the iterative thin film small antenna.

2. The bandwidth improvement method according to claim 1, characterized in that: During the topology optimization process, it is ensured that the thickness and area of ​​the iterative small film antenna are consistent with the original small film antenna.

3. The bandwidth improvement method according to claim 1, characterized in that: Smoothing is performed after each iteration.

4. The bandwidth improvement method according to claim 1, characterized in that: The mathematical expression of topology optimization is: Find:x={x1,x2,...,x n } T 0<x min <x i ≤1 Where x is the target variable, V is the design volume, T is the average stress of the magnetosphere, σ(x) is the magnetosphere stress at the target variable, V' is the optimized design volume, and x i is the material density within each unit cell, V i For the corresponding x i design volume.

5. The bandwidth improvement method according to claim 1, characterized in that: The model was constructed using COMSOL Multiphysics.

6. The bandwidth improvement method according to claim 1, wherein: The iterative small film antenna is simulated to obtain the S11 curve of the iterative small film antenna.

7. An antenna, characterized in that: It is manufactured by using the bandwidth improvement method described in any one of claims 1 to 6.

8. An electronic device, characterized in that: Comprising the antenna as claimed in claim 7.

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