An array antenna applied to three-dimensional multi-target arbitrary power distribution wireless energy transmission

Abstract

The application discloses an array antenna applied to three-dimensional multi-target arbitrary power distribution wireless energy transmission, and belongs to the field of wireless energy transmission. The array antenna comprises a transmitting antenna and a receiving antenna, and a plurality of transmitting antenna array units and a plurality of receiving antenna array units are arranged in the transmitting antenna and the receiving antenna respectively. In the transmitting antenna, the distribution of the plurality of transmitting antenna array units is divided into two layers, the transmitting antenna array units in each layer are arranged to form a circle, and an open three-dimensional space is formed. In the receiving antenna, the plurality of receiving antenna array units are distributed on two parallel planes, and the two planes are located at the center of the three-dimensional space formed by the transmitting antenna. The transmitting antenna array unit is a rectangular microstrip patch antenna. The array antenna can meet the application scene of three-dimensional multi-target arbitrary power distribution wireless power transmission.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of wireless energy transmission, and particularly relates to an array antenna applied to three-dimensional multi-target arbitrary power distribution wireless energy transmission. BACKGROUND

[0002] In recent years, wireless energy transmission based on focusing antennas (focusing wireless energy transmission) is a hot research topic, and the technology has been widely applied to communication systems, smart homes and microwave thermal therapy, etc. Microwave energy transmission (MPT) using focusing antennas is a very important energy transmission mode, and has the advantages of flexibility and stability. The research on focusing wireless energy transmission mainly focuses on two aspects: maximizing the system transmission efficiency and increasing the number of energy transmission targets.

[0003] In modern communication and practical applications, inevitably, multiple energy transmission targets will be encountered, and the power distribution of each energy receiving target is inconsistent; for example, wireless charging of multiple power different and dispersed distribution energy receiving devices, microwave thermal therapy of multiple size and position targets, etc. The prior art cannot adjust the power distribution ratio when facing the scene of multiple targets and adjustable power distribution between targets. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the application is to provide an array antenna applied to three-dimensional multi-target arbitrary power distribution wireless energy transmission.

[0005] The purpose of the application can be achieved by the following technical solutions:

[0006] An array antenna applied to three-dimensional multi-target arbitrary power distribution wireless energy transmission, comprising a transmitting antenna and a receiving antenna, and a plurality of transmitting antenna array units and a plurality of receiving antenna array units are arranged in the transmitting antenna and the receiving antenna respectively;

[0007] In the transmitting antenna, the distribution of the plurality of transmitting antenna array units is divided into two layers, the transmitting antenna array units in each layer are arranged in a circle to form an open three-dimensional space; in the receiving antenna, the plurality of receiving antenna array units are distributed on two parallel planes, and the two planes are located at the center position of the three-dimensional space surrounded by the transmitting antenna;

[0008] The transmitting antenna array unit is a rectangular microstrip patch antenna.

[0009] Further, the array antenna comprises a dielectric substrate, a rectangular patch is arranged at the center position of the dielectric substrate, a ground plate is tightly attached to the back of the dielectric substrate, a coaxial line is arranged in the transmitting antenna array unit, the coaxial line passes through the dielectric substrate and connects the rectangular patch and the ground plate.

[0010] Further, the receiving antenna array unit adopts a metal half-wave dipole.

[0011] Further, the material of the medium substrate is FR4_epoxy, the dielectric constant is 4.4, the loss tangent is 0.02, and the thickness is 3mm.

[0012] Further, in the transmitting antenna, 40 transmitting antenna array units are arranged, and the 40 transmitting antenna array units are divided into two layers, 20 transmitting antenna array units in each layer are arranged to form a circle, and an open three-dimensional space is formed.

[0013] Further, the 40 transmitting antenna array units are uniformly arranged on the medium substrate with a spacing of 0.5 wavelengths.

[0014] Further, the receiving antenna is provided with 18 receiving antenna array units, and the 18 receiving antenna array units are respectively distributed on two parallel planes.

[0015] Further, in the receiving antenna, the 18 receiving antenna array units are respectively and uniformly distributed on the two parallel planes with a spacing of 0.75 wavelengths.

[0016] Further, the transmitting antenna array unit adopts a coaxial feeding feeding mode.

[0017] Further, in the transmitting antenna array unit, the length and width of the medium substrate are 36.53cm, and the length and width of the rectangular patch are 10.68cm, and the distance between the feeding point position and the edge of the rectangular patch is 3.34cm.

[0018] The beneficial effects of the present application are as follows:

[0019] 1. The present application adopts an array antenna optimization design method applied to three-dimensional multi-target wireless power transmission, which can maximize the energy radiated by the transmitting array antenna and concentrate it in the predetermined multiple target areas.

[0020] 2. The present application can generate a desired focused electric field distribution in a three-dimensional space. The number, spatial distribution and power distribution ratio of the focal points are controllable, which can meet the application scenarios of three-dimensional multi-target wireless power transmission with arbitrary power distribution ratio.

[0021] 3. The microstrip patch antenna is used as the antenna array unit, which is uniformly arranged in two rows to form a circle and a semi-open three-dimensional space in the center. The adjacent two units are uniformly arranged on the medium substrate with a spacing of half a wavelength, which can effectively reduce the size of the array antenna, and is easy to process the antenna array and the feeding network, simple to manufacture and low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of the transmitting antenna array unit;

[0024] Figure 2 This is a top view of the transmitting antenna array unit;

[0025] Figure 3 This is a schematic diagram of the structural dimensions of the receiving antenna array unit;

[0026] Figure 4 This is a schematic diagram of the transmitting antenna;

[0027] Figure 5 This is a schematic diagram of the receiving antenna structure;

[0028] Figure 6 This is a simulation image of the focused field.

[0029] Figure 7 This is a picture of the actual transmitting antenna;

[0030] Figure 8 This is a diagram of the experimental environment for measuring the electric field strength.

[0031] Figure 9 This is a diagram of the experimental environment for measuring the received power.

[0032] Figure 10 This is a diagram showing the actual effect of the focused field.

[0033] Figure 11 These are the S-parameter curves of the optimized transmit antenna array element;

[0034] Figure 12 These are the S-parameter curves of the optimized receiving antenna array element;

[0035] Figure 13 This is a screenshot of the interface for exporting the scattering matrix from the simulation software.

[0036] Figure 14 This is a diagram showing the transmit and receive relationship between a typical antenna and its transmitting and receiving antennas.

[0037] Figure 15 It is a planar view of the electric field distribution in simulation software;

[0038] Figure 16 This is a 3D effect diagram of the antenna's electric field focusing;

[0039] Figure 17 It is a top-down view of two planes;

[0040] Figure 18 This is a diagram of the electric field distribution. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] An array antenna for wireless power transmission with arbitrary power distribution to multiple targets in three dimensions includes a transmitting antenna and a receiving antenna, each comprising multiple transmitting antenna array elements and multiple receiving antenna array elements. The specific design steps of this antenna include:

[0043] S1, determine the structural and dimensional parameters of the transmitting antenna array unit;

[0044] like Figure 1 As shown, the transmitting antenna array unit is a rectangular microstrip patch antenna, which includes a dielectric substrate 1, a rectangular patch 2 disposed at the center of the dielectric substrate 1, and a ground plane 3 attached to the back of the dielectric substrate 1. The transmitting antenna array unit adopts a coaxial feeding method. A coaxial line 4 is disposed in the transmitting antenna array unit. The coaxial line passes through the dielectric substrate 1 and connects the rectangular patch 2 and the ground plane 3.

[0045] It is worth mentioning that, in this embodiment, the dielectric substrate 1 is made of FR4_epoxy, which has a dielectric constant of 4.4, a loss tangent of 0.02, and a thickness of 3 mm.

[0046] A model of the transmitting antenna array element was built in the simulation software HFSS, and its specific parameters were optimized to obtain the optimal result, which was then determined as the element to be used later. The parameters of the transmitting antenna element after optimization by the simulation software are as follows: Figure 2 The dimensional parameters shown include the position parameters of the feed point 5, the dimensional parameters of the dielectric substrate 1, and the dimensional parameters of the rectangular patch 2;

[0047] The S-parameter curves (return loss curves) of the optimized transmit antenna array element are as follows: Figure 11As shown; return loss (S-parameter) is the reflection caused by impedance mismatch in a cable link, expressed as the ratio of incident wave power to reflected wave power at the transmission line port, and the unit is dB; the return loss at the antenna port is often used to measure the matching degree of an antenna. The smaller the return loss, the better the antenna matching degree.

[0048] from Figure 11 As can be seen, the S-parameter (return loss) of this antenna element at 5.8 GHz is -28.73 dB, indicating that the port matching effect is very good (generally, an S-parameter less than -10 dB is considered to be a match).

[0049] S2, determine the dimensional parameters of the receiving antenna array unit;

[0050] In this embodiment, the receiving antenna array unit adopts a metallic half-wave dipole. A model of the receiving antenna array unit is established in the simulation software HFSS, and simulation and parameter optimization are performed. After optimization, the final structural parameters of the receiving antenna array unit are as follows: Figure 3 As shown, the structural parameters include: dipole arm length 12.05mm, power supply port 0.3mm.

[0051] The optimized S-parameter diagram (return loss) of the receiving antenna array element is shown below. Figure 12 As shown, the S-parameter of the receiving antenna element at 5.8 GHz is -15.6 dB, indicating good matching.

[0052] S3, determine the array structure of the transmitting antenna array unit and the receiving antenna array unit;

[0053] In this embodiment, as Figure 4 As shown, the transmitting antenna has 40 transmitting antenna array elements, which are divided into upper and lower layers. The 20 transmitting antenna array elements in each layer are arranged in a circle to form a three-dimensional space that is open at both the top and bottom. These 40 transmitting antenna array elements are evenly arranged on the dielectric substrate at intervals of 0.5 wavelengths (where wavelength refers to the wavelength in air).

[0054] like Figure 5 As shown, the receiving antenna has 18 receiving antenna array elements. The 18 receiving antenna array elements are evenly distributed on two parallel planes with an interval of 0.75 wavelengths. These two planes are located at the center of the three-dimensional space enclosed by the transmitting antenna.

[0055] In this embodiment, to demonstrate the focusing effect of arbitrary power allocation across three-dimensional multi-target systems, two locations were selected as targets to be supplied with energy: target A6 and target B7. Energy was focused at these targets with a power ratio of 2:1. The focusing field simulation effect was then demonstrated.Figure 6 As shown.

[0056] S4. Build a model of the array antenna in the simulation software and simulate the scattering matrix S.

[0057] In the simulation software HFSS, a full-wave simulation of the array antenna model is performed, such as... Figure 13 As shown, after the simulation is completed, the scattering matrix S of the antenna system is exported from the simulation software for later use;

[0058] Here, the meaning of the scattering matrix S is explained as follows:

[0059] like Figure 14 As shown, a typical antenna transceiver system consists of an n antenna that is spaced D apart. t The port's transmitting antenna and an n r The receiving antenna of the port constitutes the entire wireless system; the entire wireless system can be viewed as an n-type antenna. t +n r Port networks can be used with a (n t +n r )×(n t +n r The scattering matrix S is used to represent this:

[0060]

[0061] In the formula, S tt It is the scattering parameter between the transmitting antennas, S tr It is the scattering parameter between the transmitting antenna and the receiving antenna, S rt It is the scattering parameter between the receiving antenna and the transmitting antenna, S rr These are the scattering parameters between the receiving antennas.

[0062] The normalized incident wave and transmitted wave of the transmitting antenna and receiving antenna are defined as follows:

[0063]

[0064]

[0065]

[0066]

[0067] Then the scattering matrix is:

[0068]

[0069] S5, based on S4, derive the scattering matrix S, and calculate the optimal excitation distribution a that focuses the energy at the target location. t (WCMMPTE);

[0070] Consider a general MPT system, including m transmitting antennas and n receiving antennas; the normalized incident and reflected waves of the transmitting and receiving antennas are expressed as:

[0071] [a t ] = [a1,a2,···,a m ] T (2)

[0072] [a r ] = [a m+1 ,a m+2 ,···,a n ] T ,

[0073] [b t ] = [b1,b2,···,b m ] T ,

[0074] [b r ] = [b m+1 ,b m+2 ,···,b m+n ] T ,

[0075] In the formula, T represents the matrix transpose.

[0076] By a general definition, the power transfer efficiency (PTE) of an MPT system is defined as the ratio of the power received by the receiving antenna to the total power transmitted by the transmitting antenna, denoted by η, and expressed as:

[0077]

[0078] When there is only one receiving antenna, the maximum efficiency η and the corresponding excitation [a] are obtained. t The process is a simple characteristic equation problem, which is solved in MMPTE (Maximum Transmission Power Efficiency Method). When the number of receiving targets exceeds 1, constraints can be introduced to control the received power of each receiving antenna and adjust the ratio of the received power among multiple receiving antennas. This forms a more complex QCQP (Quadratic Constraint Quadratic Programming) problem.

[0079] In a practical MPT system, there are two types of receiving antennas. One is the target receiving antenna at the location of the target to be powered, and the other is a virtual test receiving antenna. The purpose of this is to suppress the energy density in other non-target areas within the three-dimensional WPT range. The energy radiated by the transmitting antenna is expected to be focused onto those target receiving antennas (the locations of the target to be powered).

[0080] The QCQP problem with inequality constraints is described as follows:

[0081]

[0082] Among them, set P E and P S These represent: the receiving antenna at the energy focusing point (at the target location) and the receiving antenna at the energy suppression point; P E and P S The number of antennas in the set are p and q, respectively, note that p + q = n; obviously, the size of p is the number of targets to be powered; however, the above constraint can only guarantee that the power is focused as much as possible on the defined receiving targets, and the power distribution among these receiving targets cannot be adjusted; therefore, given P E The receiving targets are constrained by equations to precisely control the receiving power allocation ratio among them; expressed as:

[0083] k1|b m+1 | 2 =k2|b m+2 | 2 =k3|b m+3 | 2 =...=k p |b m+p | 2 (5)

[0084] Therefore, the desired arbitrary received power allocation ratio can be achieved by adjusting the weighting coefficients (k1,k2,…,k). p To achieve precise control.

[0085] Note that, compared to equality constraints, the inequality constraints in the previous formula (4) are difficult to apply in practical engineering; furthermore, the power received by the receiving antennas in the PS set is very small, so the differences between them can be ignored; therefore, a large coefficient k is introduced to transform the inequality constraints into equality constraints. Considering the previous formula (5), formula (4) becomes:

[0086]

[0087] Therefore, the maximum transmission efficiency of the system and the power allocation of the receiving target can be guaranteed simultaneously; here, the QCQP problem with equality constraints can be solved by the Lagrange multiplier method; the answer to formula (6) is expressed mathematically as:

[0088] [a t ] = [A] -1 [S rt ] H ([S rt [A] -1 [S rt ] H )-1 [y], (7)

[0089] Where, [A] = [S] rt ] H [S rt ], [S rt ] represents the scattering matrix; the superscript H represents the conjugate transpose of the matrix; [y] is a normalized n-dimensional vector with n weight coefficients, satisfying:

[0090]

[0091] When the ratio between the received power of specific targets is fixed according to actual needs, k1, k2, ..., k p The p weighting coefficients have also been determined.

[0092] In addition, in order to suppress the power at other locations in three-dimensional space, the value of k should be relatively large.

[0093] By solving formula (7) using MATLAB software, the optimal excitation distribution for the desired focusing effect can be obtained [a] t The system efficiency can also be calculated according to the definition as 23.69%, with the efficiency at the target A6 being 15.79% and the efficiency at the target B7 being 7.89%, resulting in a ratio of 2:1.

[0094] S6. In the simulation software, view the electric field distribution in the target area (i.e., the three-dimensional space enclosed by the transmitting antenna) to verify whether the expected effect has been achieved.

[0095] The specific steps include:

[0096] S61, remove the receiving antenna and place a plane at the target location to observe the electric field distribution;

[0097] To view the electric field distribution of the antenna, the receiving antenna is no longer needed. The purpose of placing the receiving antenna is to focus the energy emitted by the antenna onto the vicinity of the receiving antenna that you want it to focus on. The optimal excitation distribution in this case has already been calculated in S5, so the test antenna is removed from the original antenna model here.

[0098] In HFSS software, to view the electric field distribution at a specific location, you first need to draw a line or plane at that location, and then view the electric field distribution along that line or plane. It's worth noting that these lines and planes are drawn separately for viewing the electric field and are not part of the antenna system itself. A planar representation is shown below. Figure 15 As shown,

[0099] S62, Set the antenna excitation, and apply the obtained three optimal excitation distributions a tInput simulation software;

[0100] Antennas are tools for receiving and transmitting electromagnetic waves. If you want an antenna to transmit electromagnetic waves, you need to input a signal to the antenna. The corresponding operation in the simulation software is to set the amplitude and phase of the input signal to the input port (lumped port) of the transmitting antenna. In this invention, the amplitude and phase values ​​calculated by formula (6) in MATLAB (see Table 1) are input, and the excitation data of 40 transmitting antennas are saved into the HFSS simulation model.

[0101] Table 1

[0102]

[0103]

[0104] S63, view the electric field distribution;

[0105] Use the built-in functions of HFSS software to view the electric field distribution on the plane drawn by S61; see the 3D effect of antenna electric field focusing. Figure 16 See the top-down views of the upper and lower planes. Figure 17 The electric field distribution diagrams for (a) and (b) are shown in the figure. Figure 18 In (a) and (b), it can be seen that the antenna forms two focal points at the target location, and the electric field distribution is uneven, thus achieving the desired effect.

[0106] S7, make the array antenna instance model into a physical object for testing;

[0107] The test is divided into two parts. The first experiment is to measure the electric field intensity distribution within the space enclosed by the transmitting antenna, and the second experiment is to measure the actual received power at the location of the target to be transmitted.

[0108] The specific steps include:

[0109] S71, physical fabrication, actual transmitting antenna as shown Figure 7 As shown.

[0110] S72, Test the electric field intensity distribution within the spatial region enclosed by the transmitting antenna;

[0111] Use such as Figure 8 The three-dimensional near-field test platform and vector network analyzer shown were used to test the antenna. The measured electric field data were input into MATLAB to plot the measured electric field distribution. Figure 10 ,and Figure 6 The simulated electric field distribution diagram is basically consistent.

[0112] S73, measures the actual received power at the location of the target to be transmitted;

[0113] Use such as Figure 9 The spectrum analyzer and printed dipole shown were used to test the actual received power at the target location; the test results and the calculated efficiency and ratio are shown in Table 2. It can be seen that when the printed dipole is placed at the target location, the ratio of the power actually received by the dipole is 2.05:1, which is basically consistent with our expected 2:1.

[0114] Table 2

[0115]

[0116] The physical test results and simulation results are consistent, indicating that our antenna can focus energy on multiple targets in three-dimensional space with arbitrary power distribution ratios, with remarkable effect.

[0117] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0118] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. An array antenna for wireless power transmission with arbitrary power distribution to three-dimensional multi-target targets, characterized in that, It includes a transmitting antenna and a receiving antenna, and the transmitting antenna and the receiving antenna are respectively provided with multiple transmitting antenna array units and multiple receiving antenna array units; In the transmitting antenna, the distribution of multiple transmitting antenna array elements is divided into upper and lower layers. The transmitting antenna array elements in each layer are arranged in a circle to form a three-dimensional space that is open at both the top and bottom. In the receiving antenna, multiple receiving antenna array elements are distributed on two parallel planes, and these two planes are located at the center of the three-dimensional space enclosed by the transmitting antenna. The transmitting antenna array unit is a rectangular microstrip patch antenna; The specific details of the three-dimensional multi-target arbitrary power distribution wireless power transmission are as follows: The wireless power transmission problem is transformed into a quadratic constrained quadratic programming model with inequality constraints, as follows: in, For power transmission efficiency; set P E and P S These represent the receiving antennas at the energy focusing point and the receiving antennas at the energy suppression point, respectively; set P E and P S The number of antennas in the array are p and q, respectively. , n This represents the total number of receiving antennas. Given set P E The receiving target is subjected to equation constraints to precisely control the receiving power of each receiving antenna. The equation constraints are as follows: in, m The total number of transmitting antennas; the desired arbitrary receive power allocation ratio is determined by adjusting the weighting coefficients k1, k2, ..., k. p To achieve precise control; Introducing coefficients k The quadratic programming model with inequality constraints is transformed into a quadratic programming model with equality constraints: By solving the above equation constraints using the Lagrange multiplier method, the optimal excitation distribution vector of the plurality of transmitting antenna array elements is obtained. The amplitude and phase of the input signal of each transmitting antenna array element are adjusted according to the optimal excitation distribution vector, so that the energy can be precisely proportionally distributed in the three-dimensional space.

2. The array antenna for arbitrary power distribution wireless power transmission for three-dimensional multi-target applications according to claim 1, characterized in that, The device includes a dielectric substrate, a rectangular patch at the center of the dielectric substrate, a ground plane attached to the back of the dielectric substrate, and a coaxial cable in the transmitting antenna array unit. The coaxial cable passes through the dielectric substrate and connects the rectangular patch and the ground plane.

3. An array antenna for arbitrary power distribution wireless power transmission for three-dimensional multi-target applications according to claim 1, characterized in that, The receiving antenna array unit uses a metallic half-wave dipole.

4. An array antenna for arbitrary power distribution wireless power transmission for three-dimensional multi-target applications according to claim 2, characterized in that, The dielectric substrate is made of FR4_epoxy, with a dielectric constant of 4.4, a loss tangent of 0.02, and a thickness of 3 mm.

5. An array antenna for wireless power transmission with arbitrary power distribution for three-dimensional multi-target applications according to claim 1, characterized in that, The transmitting antenna is equipped with 40 transmitting antenna array units, which are divided into upper and lower layers. The 20 transmitting antenna array units in each layer are arranged in a circle to form a three-dimensional space that is open at both ends.

6. An array antenna for wireless power transmission with arbitrary power distribution for three-dimensional multi-target applications according to claim 5, characterized in that, The 40 transmitting antenna array elements are uniformly arranged on the dielectric substrate at 0.5 wavelength intervals.

7. An array antenna for wireless power transmission with arbitrary power distribution for three-dimensional multi-target applications according to claim 1, characterized in that, The receiving antenna is provided with 18 receiving antenna array elements, which are distributed on two parallel planes, one above the other.

8. An array antenna for wireless power transmission with arbitrary power distribution for three-dimensional multi-target applications according to claim 7, characterized in that, In the receiving antenna, 18 receiving antenna array elements are evenly distributed on two parallel planes with an interval of 0.75 wavelengths.

9. An array antenna for arbitrary power distribution wireless power transmission for three-dimensional multi-target applications according to claim 2, characterized in that, The transmitting antenna array unit adopts a coaxial feeding method.

10. An array antenna for wireless power transmission with arbitrary power distribution for three-dimensional multi-target applications according to claim 9, characterized in that, In the transmitting antenna array unit, the length and width of the dielectric substrate are both 36.53cm, the length and width of the rectangular patch are both 10.68cm, and the distance from the feed point to the edge of the rectangular patch is 3.34cm.

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