A design method of a low profile antenna wall

Abstract

The application belongs to the technical field of surface wave antennas, and relates to a low-profile antenna wall for multi-scene MIMO communication, which is formed by a plurality of impedance unit arrays, each impedance unit comprising an impedance adjusting layer, a dielectric layer and a grounding layer from top to bottom; the impedance adjusting layer array forms an impedance adjusting plate, the dielectric layer array forms a dielectric substrate, and the grounding layer array forms an antenna grounding plate; the impedance adjusting layer has a capacitive resistance, and the impedance of the corresponding unit is adjusted by adjusting the gap; an external port is prefabricated on the lower surface of the antenna grounding plate. A design method thereof is also disclosed, a specific beam control antenna can be designed according to the corresponding scene, the corresponding statistical optimal directivity diagram is obtained, the corresponding surface wave antenna is designed by using artificial impedance, the required optimal directivity diagram distribution is realized through the surface wave antenna, and then the optimal degree of freedom and channel capacity of the entire antenna array surface are obtained, so that optimal MIMO communication can be realized.

Description

Technical Field

[0001] This invention belongs to the field of surface wave antenna technology, specifically relating to a design method for a low-profile antenna wall. Background Technology

[0002] After decades of development, wireless communication technology has permeated all aspects of society and is closely related to modern life. Due to the continuous increase in communication speed and bandwidth, the framework of the Internet of Things is gradually taking shape in human society. Whether in industrial production or daily activities, various mobile communication devices have gradually become the most commonly used tools. As a key transceiver device in wireless communication, the demand for antennas is also increasing with the changing application scenarios. 6G IoT systems emphasize multi-user interconnection and coordinated control, thus placing higher demands on MIMO communication. As a control relay in a scenario, the antenna array must achieve maximum gain to cover the scene and realize optimal MIMO communication. Therefore, it is necessary to increase the main lobe width while ensuring antenna gain, thus placing high demands on the antenna design.

[0003] With current technology, improving scene coverage is simply achieved by increasing the number of antennas. These antennas generally use low-gain, wide main lobes, resulting in overlapping coverage of the same area. This is actually an inefficient design, wasting energy. Furthermore, the more ports there are, the more complex the feeding circuitry and port coupling become. In addition, many antenna array designs only consider the profile or coupling, without studying the correlation between the radiation patterns corresponding to the MIMO antenna ports. Summary of the Invention

[0004] The purpose of this invention is to provide a design method for low-profile antenna walls, which solves the energy waste problem introduced by the overlapping area coverage between conventional MIMO antennas.

[0005] This invention is achieved through the following technical solution:

[0006] A design method for a low-profile antenna wall, wherein the low-profile antenna wall is composed of an array of several impedance elements, each impedance element comprising an impedance adjustment layer (1-2), a dielectric layer (1-5), and a ground layer (1-6) from top to bottom.

[0007] An array of impedance adjustment layers (1-2) forms an impedance adjustment plate (1-7), an array of dielectric layers (1-5) forms a dielectric substrate (1-3), and an array of ground layers (1-6) forms an antenna ground plane (1-4).

[0008] The impedance adjustment layer (1-2) has capacitive resistance, and the corresponding unit impedance is adjusted by adjusting the gap, so as to realize the excitation of surface waves through different impedance units;

[0009] An external port (1-1) is pre-fabricated on the lower surface of the antenna ground plane (1-4).

[0010] The design method for the low-profile antenna wall includes the following steps:

[0011] S1. First, determine the main propagation path of the incoming wave and the angular power distribution of the incoming wave with the main lobe ranging from -90 to 90° when the antenna is used as the receiving end.

[0012] S2. Calculate the reception based on the power distribution of the incoming wave angle, select a basis function system, expand the current distribution on the antenna aperture using the basis function system, analyze the equivalent current distribution corresponding to the low-profile antenna wall, and calculate the expansion coefficient matrix that meets the requirements.

[0013] S3. Obtain the spatial angle distribution of the statistically optimal radiation pattern based on the expansion coefficient matrix;

[0014] S4. Based on the spatial angle distribution of the optimal radiation pattern, the main lobe distribution of the corresponding port is obtained. Through the holographic mapping relationship of the surface wave antenna, the surface impedance distribution corresponding to the impedance adjustment layer (1-2) is calculated, and a low profile antenna wall is designed.

[0015] Furthermore, the external ports (1-1) are linearly arranged along the horizontal axis of the dielectric substrate (1-3).

[0016] Furthermore, when the external port (1-1) is set to four ports, the distances from the center of the dielectric substrate (1-3) are 40 mm, 24 mm, 24 mm, and 40 mm, respectively.

[0017] Furthermore, S2 specifically refers to:

[0018] First, a basis function system is selected, and the current distribution on the antenna aperture is expanded using the basis function system. Then, the far-field radiation pattern of the current distribution corresponding to the m-th characteristic mode is obtained by integrating with the dyadic Green's function. :

[0019] ;

[0020] in The basis function is used to represent the current distribution corresponding to the m-th characteristic mode. The weight of the expansion For the far-field dyadic Green's function, For solid angles, The source position coordinate vector; For the first Far-field pattern corresponding to each basis function;

[0021] Based on the power distribution of the incoming wave angle The received voltage at the antenna port is obtained. :

[0022] ;

[0023] Based on the received voltage at the antenna port Calculate the covariance matrix of the antenna port voltage. :

[0024] ;

[0025] in The power angular spectrum of the incoming wave. The index of the basis function. Number the antenna ports; It is the first p The current distribution corresponding to each characteristic antenna mode is represented by a basis function. Expanded weighted conjugation;

[0026] Integral expression above for The matrix representation of covariance ;

[0027] Considering the radiated power normalization condition and the gain constraint condition, using express The Column, then we get:

[0028]

[0029]

[0030] in , Let represent the real part of the impedance matrix of the basis function system. Free-space wave impedance;

[0031] Directed matrix Introducing heat loss resistor To limit the gain, let , The total power fed to the antenna array, including radiated power and loss power, is expressed as the expansion coefficient matrix. use Calculations are performed to obtain the optimal solution that satisfies the above two conditions. ;

[0032] in For matrix The largest corresponding eigenvalue decomposition An eigenvector matrix with eigenvalues.

[0033] further, The range is from 1 to 121. The range is 1 to 4.

[0034] Furthermore, S2 specifically refers to:

[0035] The basis function system is chosen to be a square pulse basis function system, which is expressed as:

[0036] ;

[0037] in The rectangular coordinate components of the center of the nth primitive are... .

[0038] Furthermore, S2 specifically refers to:

[0039] In S3, the expansion coefficient matrix obtained in S2 is... Substitution In the middle, we get the first The elevation angle of the radiation pattern corresponding to each antenna And the azimuth angle of the antenna pattern .

[0040] Furthermore, S2 specifically refers to:

[0041] The specific process of S4 is as follows:

[0042] Simulation was performed using electromagnetic simulation software. After setting boundary conditions, the surface wave dispersion curve of the impedance element was obtained by using incident wave phase control. The element phase shift at the corresponding frequency point was obtained using the surface wave dispersion curve, and the corresponding impedance was calculated.

[0043] ;

[0044] in It is free-space wave impedance. At the speed of light, Let be the side length of the unit. The intrinsic frequency, The calculated impedance is given by j, where j is the imaginary sign and Φx is the tangential dispersion phase.

[0045] g is the width of the impedance gap;

[0046] The elevation angle from the antenna pattern And the azimuth angle of the antenna pattern The main lobe distribution of the spatial radiation pattern is obtained, and based on its and From the given values, we can obtain the corresponding beam control formula:

[0047] ;

[0048] in The average impedance, For modulation impedance, For free space wavenumber, This is the unit orientation vector. The equivalent refractive index is given, and x and y are the antenna array coordinate parameters of the corresponding impedance element. The spatial multiplexing of the port beam for the antenna array is constructed using the linear superposition relationship.

[0049] Compared with the prior art, the present invention has the following beneficial technical effects:

[0050] This invention discloses a design method for a low-profile antenna wall. The low-profile antenna wall is composed of an array of impedance elements. Each impedance element includes, from top to bottom, an impedance adjustment layer, a dielectric layer, and a ground layer, forming a three-layer structure design. Compared to conventional high-gain antenna arrays, it has an extremely low profile, effectively improving space utilization. The feeding structure of the antenna wall designed in this invention mainly consists of a ground layer and a feeding port. The structure is simple and has no complex feeding backend, which can effectively reduce costs and improve reliability.

[0051] Based on the corresponding scenario, a specific beam control antenna can be designed. The corresponding statistical optimal radiation pattern is obtained using an algorithm, and a corresponding surface wave antenna is designed using artificial impedance. The required optimal radiation pattern distribution is achieved through the surface wave antenna, thereby obtaining the optimal degrees of freedom and channel capacity of the entire antenna array. This enables optimal MIMO communication, avoids the waste of space energy, improves the working efficiency of the antenna, and can better realize the role of IoT control antenna within a certain space. Furthermore, due to its extremely low profile, it can be placed on an empty wall without taking up too much space, and has good commercial application prospects. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of MIMO communication using an antenna wall in an indoor scenario.

[0053] Figure 2 This is a flowchart of the MIMO antenna array pattern design and optimization process;

[0054] Figure 3 This is a distribution of normalized basis function current weights corresponding to the four antenna statistical optimal operating modes when the number of characteristic modes is limited to four. In the figure, 1, 2, 3, and 4 represent the four independent characteristic current distributions calculated, and the numbers 1, 2, 3, and 4 correspond to ports 1, 2, 3, and 4.

[0055] Figure 4 This refers to the normalized far-field radiation patterns corresponding to the four antenna statistically optimal operating modes when the number of characteristic modes is limited to four; the numbers 1, 2, 3, and 4 represent... Figure 3Antenna patterns at ports 1, 2, 3, and 4 corresponding to the characteristic current distribution in the middle;

[0056] Figure 5 a is a schematic diagram of the layer structure of the surface wave antenna;

[0057] Figure 5 b is a front view of the impedance adjustment plate located at the top layer;

[0058] Figure 5 c is Figure 5 A magnified view of point A in b;

[0059] Figure 5 d is Figure 5 The front and top views of the enlarged partial schematic diagram at point B in b;

[0060] Figure 6 This is a schematic diagram of the optimal MIMO antenna wall degrees of freedom;

[0061] Figure 7 This is a schematic diagram of the optimal MIMO antenna wall channel capacity.

[0062] The components include: 1. Antenna wall; 2. Computer equipment; 3. Refrigeration equipment; 4. Air conditioning equipment; 5. Kitchen equipment.

[0063] 1-1 External port; 1-2 Impedance adjustment layer; 1-3 Dielectric substrate; 1-4 Antenna ground plane; 1-5 Dielectric layer; 1-6 Grounding layer; 1-7 Impedance adjustment plate. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0065] The components described and illustrated in the accompanying drawings and embodiments of this invention can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on the accompanying drawings and embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0066] It should be noted that the terms “comprising,” “including,” or any other variations are intended to cover non-exclusive inclusion, such that a process, element, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to the process, element, method, article, or apparatus.

[0067] like Figure 1 As shown, this invention proposes a low-profile antenna wall for MIMO communication, and proposes a method for calculating and optimizing the statistically optimal radiation pattern for the corresponding scenario, and finally proposes an antenna design method.

[0068] Figure 1 The image shows an indoor application diagram of this antenna wall. Due to its extremely low profile and planar design, the antenna can be placed on an empty wall surface in an indoor space (it can also be placed on a wall surface in outdoor scenarios). It mainly includes the designed four-port antenna wall 1, and the computer equipment 2, refrigeration equipment 3, air conditioning equipment 4, and common kitchen equipment 5 used in the indoor scenario. The designed four-port antenna wall acts as a relay antenna, receiving signals from the computer equipment 2, refrigeration equipment 3, air conditioning equipment 4, and common kitchen equipment 5 to obtain the operating status of each control device. It then transmits control signals according to the instructions from the control terminal, thereby controlling all the above devices to achieve their corresponding functions. The objects in the diagram are all commonly used smart home devices indoors, including some immovable equipment. This illustrates that the location of the devices in the indoor space scene necessitates that the control antenna has specific angular spatial requirements, i.e., the direction of arrival must be within a certain angular spectrum range. By optimizing the algorithm to design the corresponding antenna, higher performance MIMO communication can be achieved.

[0069] The MIMO communication antenna wall in the 30GHz band is 160. 160 mm, bandwidth 20%, antenna profile 1.5 mm.

[0070] The 30GHz MIMO communication antenna wall is composed of impedance elements, with 8080 elements, a dielectric substrate thickness of 1.016 mm, a dielectric constant of 2.2, and a loss tangent of 0.0009. This impedance element includes, from top to bottom, an impedance adjustment layer 1-2, a dielectric layer 1-5, and a ground layer 1-6; as shown... Figure 5 As shown in Figure a, the impedance adjustment layer 1-2 array forms the impedance adjustment plate 1-7, the dielectric layer 1-5 array forms the dielectric substrate 1-3, and the ground layer 1-6 array forms the antenna ground plane 1-4; the impedance adjustment layer 1-2 has capacitive resistance, and the corresponding unit impedance can be adjusted by adjusting the slot width, so the surface wave excitation can be achieved through different impedance units.

[0071] The following description is based on specific examples.

[0072] like Figure 2 As shown, the design method of the low-profile antenna wall includes the following steps;

[0073] The first step is to determine the angle distribution of the incoming wave in the propagation environment.

[0074] In real-world operating environments, the angle of arrival of incoming waves is often not a fixed value, but rather a random variable with certain statistical characteristics. By incorporating the power angle spectrum of the incoming waves into the optimal radiation pattern design, it is possible to obtain the optimal radiation pattern design that achieves statistically best MIMO performance. This is achieved by measuring or estimating the power distribution at the angle of arrival of the incoming waves in the actual operating environment. .

[0075] Step 2: Calculate the optimal radiation pattern:

[0076] First, we need to determine the orthogonal basis function system for the aperture current expansion. Here, we choose the square pulse basis function system.

[0077] The square pulse basis function system can be expressed as follows:

[0078]

[0079] in The rectangular coordinate components of the center of the nth primitive are... .

[0080] The preferred embodiment parameters are: the number of feature patterns equals 4, and the array size is [missing information]. The basis function system is chosen as Square pulse basis function system, wave distribution It is distributed only in the xoy plane and has a mean of The truncated Gaussian distribution.

[0081] The current distribution on the antenna aperture is expanded using this basis function system to obtain the corresponding expansion coefficients. Then, by integrating with the far-field dyadic Green's function, the far-field radiation pattern of the current distribution corresponding to the m-th characteristic mode is obtained.

[0082]

[0083] in The basis function is used to represent the current distribution corresponding to the m-th characteristic mode. The weight of the expansion For the far-field dyadic Green's function, For solid angles, This is the source position coordinate vector. For the first The far-field radiation pattern corresponding to each basis function can be determined based on the power distribution at the incoming wave angle. Received voltage at antenna port

[0084]

[0085] Furthermore, the covariance matrix of the received voltage at the antenna port can be obtained. satisfy:

[0086]

[0087] in The power angular spectrum of the incoming wave. These are the basis function indices, all ranging from 1 to 121. The antenna port numbers range from 1 to 4.

[0088] Integral expression above for The matrix representation of the covariance can be obtained. .

[0089] Considering the normalization condition of radiated power and gain limiting conditions , express The From this, we can obtain:

[0090]

[0091]

[0092] in , Let represent the real part of the impedance matrix of the basis function system. For free-space wave impedance. To the matrix Introducing heat loss resistor It can limit the gain, making , The total power fed to the antenna array, including radiated power and loss power, is expressed as the expansion coefficient matrix. use Calculations can yield the optimal solution that satisfies the above two conditions. .in For matrix The largest corresponding eigenvalue decomposition An eigenvector matrix with eigenvalues.

[0093] Step 3: Obtain the spatial angle distribution of the statistically optimal radiation pattern:

[0094] Expand the coefficient matrix obtained in the second step Substitution The first one can be obtained from the middle. The radiation pattern corresponding to each antenna.

[0095] From the radiation pattern obtained through the above steps, the main lobe information of the four ports can be obtained, that is, the corresponding... and The values ​​are such that antenna design can be carried out based on this information;

[0096] The elevation angle of the antenna pattern. The azimuth angle of the antenna pattern represents the characteristics of the main lobe.

[0097] Step 4: Antenna Design Process

[0098] The first step is the impedance matching process, which can be simulated using electromagnetic simulation software. After setting the boundary conditions, the surface wave dispersion curve of the impedance element can be obtained by using incident wave phase control. The element phase shift at the corresponding frequency (30GHz) obtained from the dispersion curve is then used. The corresponding impedance can be calculated:

[0099]

[0100] in It is free-space wave impedance. At the speed of light, Let be the side length of the unit. The intrinsic frequency, The calculated impedance is given by j, where j is an imaginary number. The phase of the tangential dispersion is denoted by g; g is the impedance gap width.

[0101] The main lobe distribution of the spatial radiation pattern is obtained from the above optimization steps, and based on its... and From the given values, we can obtain the corresponding beam control formula:

[0102]

[0103] in The average impedance, For modulation impedance, For free space wavenumber, This is the unit orientation vector. For the equivalent refractive index, the spatial multiplexing of the port beam for the antenna array can be constructed using the linear superposition relationship. Essentially, there is a holographic mapping relationship between space waves, surface waves, and impedance surfaces. By calculating the beam control formula, the generation of space waves can be obtained, and beams can be applied as needed. and The corresponding beam is generated by the values ​​of the impedance mapping. Therefore, the design of a low-profile antenna wall can achieve a statistically optimal radiation pattern through an impedance mapping relationship.

[0104] The low-profile antenna wall obtained from the simulation is used to evaluate the corresponding MIMO communication performance based on its specific far-field radiation pattern: the degrees of freedom and channel capacity are calculated.

[0105] Degrees of freedom are used to characterize correlation performance. Based on the channel matrix and corresponding correlation coefficient matrix obtained from simulation, this correlation coefficient matrix is ​​mapped to a scalar value, which is the degree of freedom. Therefore, a larger degree of freedom indicates that the MIMO antenna has better overall correlation performance. Channel capacity is obtained by simulating the MIMO channel matrix based on the input antenna pattern and the selected channel model. Then, the MIMO channel is normalized by ensuring that the transmit power of the transmitter remains constant throughout the simulation. Finally, the channel capacity can be calculated based on the given average signal-to-noise ratio and MIMO channel matrix, which can also be used to evaluate the performance of MIMO communication. Therefore, degrees of freedom and channel capacity are used as evaluation parameters.

[0106] Figure 3 and Figure 4 The images show the distribution maps of the normalized weights of the statistical optimal basis functions corresponding to the four feature patterns optimized under the above preferred embodiments, as well as the corresponding normalized far-field orientation maps. Figure 3 Given a truncated Gaussian wave distribution function and a square pulse basis function system, the calculated amplitude weight distribution values ​​are shown. The color intensity represents the weight level. It can be seen that the current modes at the four ports are orthogonal. Similarly, Figure 4 To utilize Figure 3 The far-field radiation pattern obtained by integrating the current distribution through the dyadic Green's function shows that the corresponding main lobes are staggered, achieving an optimal coverage of spatial energy.

[0107] Figure 5 a is a schematic diagram of the overall low-profile antenna wall. Figure 5 Figure b shows the front view of the designed antenna array, containing 80... An 80° square impedance matching unit; 1-3 in the figure is 160°. 160 A dielectric substrate with a dielectric constant of 2.2 and a size of 1.016 mm is shown. In the figure, 1-4 is the antenna ground plane. The four ports below the antenna ground plane 1-4 are arranged linearly along the horizontal axis, with distances from the center of 40 mm, 24 mm, 24 mm, and 40 mm, respectively. Each port corresponds to a radiation pattern.

[0108] The four antenna feeds below antenna ground planes 1-4 employ a monopole design, with an antenna length of 4.75 mm. Figure 5The outer radius of the medium 1-1 at port c is 0.86 mm, and there is a corresponding connector below it. For example... Figure 5 As shown in Figure d, the impedance element comprises an impedance adjustment layer 1-2, a dielectric layer 1-5, and a ground layer 1-6. The dielectric constant of dielectric layer 1-5 is 2.2, forming the basis of the holographic antenna. Impedance adjustment layer 1-2 has capacitive resistance; by adjusting the slot width, the corresponding element impedance can be adjusted, thereby realizing surface wave propagation and further achieving beam control. The impedance of the impedance element can be calculated using electromagnetic simulation software, and its slot width and corresponding impedance can be mapped one-to-one.

[0109] Figure 6 and Figure 7 This refers to the MIMO communication performance evaluation of the obtained four-port antenna wall, which is obtained through simulation. Figure 5 In this embodiment, the antenna's four-port radiation pattern (center frequency 30GHz) is used to calculate the four-port degrees of freedom of the corresponding MIMO antenna and the overall channel capacity of the antenna. Figure 6 It can be seen that the corresponding four-port antenna has extremely high degrees of freedom, exceeding 3.85 and very close to 4. The radiation patterns of the four modes can be considered spatially orthogonal, and the overall channel capacity also meets the requirements, showing a significant improvement with angle expansion, reaching the system's optimal value. Therefore, this design can effectively improve the degrees of freedom between antennas and the overall channel capacity of the system, thereby achieving the optimal value and meeting the requirements of optimal MIMO communication in the scenario.

[0110] In summary, this application proposes a comprehensive method for low-profile antenna walls and their statistically optimal radiation patterns for multi-scenario MIMO communication, including specific algorithm design and corresponding antenna implementation, which can be applied to future intelligent IoT systems.

[0111] Existing conventional omnidirectional antennas employ omnidirectional beam coverage, but full-space coverage is essentially a waste of energy. Next-generation communication systems strive for more efficient communication connections, especially for control antennas in certain scenarios. Achieving optimal coverage within a specific angular range avoids energy waste across all angles, thereby improving overall system performance. Currently, there are few schemes for statistically optimal radiation pattern design, and even fewer that include specific antenna array implementations. Therefore, this invention guides array design from the statistically optimal angle of the antenna array. It uses the incident wave within a certain angular range as the basis for analysis and proposes the optimal current distribution obtained from this incident wave, similarly yielding the far-field radiation pattern distribution. Based on the specific main lobe information of the obtained statistically optimal radiation pattern, it combines it with a surface wave antenna, introducing surface waves using impedance mapping. Furthermore, since surface waves and space waves have a holographic mapping relationship, the corresponding impedance distribution is further obtained, thus realizing the specific antenna form of the statistically optimal radiation pattern.

[0112] The first challenge of this invention lies in introducing the concept of statistically optimal radiation pattern design. Most design schemes are limited to single-antenna optimization or related radiation pattern design. Many passive antenna arrays can only be designed for specific directions, resulting in fixed directions, which are low-cost but functionally limited. Active antenna arrays can control beam scanning but are more expensive. Therefore, this invention proposes an antenna array optimization design algorithm for incident waves with a power angle spectrum within a specific spatial range. The incident wave is randomly incident within a spatial angle range as the initial design condition. Based on the incident wave, the corresponding spatial distribution basis function is obtained. Using the basis function, the current distribution under the statistically optimal design condition is obtained, and the far-field radiation pattern of different antenna ports can be derived. The resulting array port radiation pattern can be considered spatially orthogonal, meaning the degrees of freedom between antenna ports are optimal, thereby improving the overall antenna array performance. This invention is the first to incorporate statistically optimal radiation pattern design into array considerations. Due to its significant improvement in array degrees of freedom, it is well-suited for MIMO communication in specific scenarios, enabling the channel capacity of the local system to reach statistical optimization. Statistically optimal radiation pattern design is the core idea of ​​this invention and the first major technical means that distinguishes it from other antenna design patents.

[0113] The second challenge of this invention concerns the antenna configuration for achieving the optimal radiation pattern. Traditional antenna design for statistically optimal arrays typically employs a single dipole as the unit, controlling the feed network to achieve a specific radiation pattern. However, this approach is limited to ideal algorithmic scenarios and does not consider the actual implementation of the antenna. For an ideal dipole array, coupling factors, according to the design, become an obstacle to implementation. Furthermore, the antenna array formed by the dipole and its feed network has significant space requirements, making this solution commercially unviable considering many future applications. Therefore, this invention, based on the proposed statistically optimal radiation pattern design method, adopts a low-profile antenna wall as the implementation. The advantages of this design approach are:

[0114] (1) Low profile, lightweight antenna structure, suitable for installation on empty wall surfaces, reducing the complexity of physical space layout, and has good commercial application prospects;

[0115] (2) The feed network is simple, so the antenna is easier to fabricate. Only the PCB process and ports need to be considered, without the need for complex feed network design.

[0116] (3) Beamforming is relatively easy to implement because the antenna pattern generated by the statistical optimization algorithm is a major problem. The conventional antenna configuration is very complex to implement, but it can be more easily implemented using a surface wave antenna. Therefore, after considering the algorithm requirements and the actual application requirements, the surface wave antenna combined with the statistical optimal pattern is taken as the main design scheme of this invention. It has good theoretical basis, and the antenna structure is very suitable for the control antenna requirements of the Internet of Things in future communication systems, and has good market demand.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method of designing a low profile antenna wall, characterized by, The low-profile antenna wall is composed of an array of impedance elements, each of which includes an impedance adjustment layer (1-2), a dielectric layer (1-5), and a ground layer (1-6) from top to bottom. An array of impedance adjustment layers (1-2) forms an impedance adjustment plate (1-7), an array of dielectric layers (1-5) forms a dielectric substrate (1-3), and an array of ground layers (1-6) forms an antenna ground plane (1-4). The impedance adjustment layer (1-2) has capacitive resistance, and the corresponding unit impedance can be adjusted by adjusting the gap, so as to realize the excitation of surface waves through different impedance units. An external port (1-1) is pre-fabricated on the lower surface of the antenna ground plane (1-4). The design method for the low-profile antenna wall includes the following steps: S1. First, determine the main propagation path of the incoming wave and the angular power distribution of the incoming wave with the main lobe ranging from -90 to 90° when the antenna is used as the receiving end. S2. Calculate the reception based on the power distribution of the incoming wave angle, select a basis function system, expand the current distribution on the antenna aperture using the basis function system, analyze the equivalent current distribution corresponding to the low-profile antenna wall, and calculate the expansion coefficient matrix that meets the requirements. S3. Obtain the spatial angle distribution of the statistically optimal radiation pattern based on the expansion coefficient matrix; S4. Based on the spatial angle distribution of the optimal radiation pattern, the main lobe distribution of the corresponding port is obtained. Through the holographic mapping relationship of the surface wave antenna, the surface impedance distribution corresponding to the impedance adjustment layer (1-2) is calculated, and a low profile antenna wall is designed.

2. The method of designing a low profile antenna wall of claim 1, wherein, The external ports (1-1) are arranged linearly along the horizontal axis of the dielectric substrate (1-3).

3. The method of designing a low profile antenna wall according to claim 2, wherein, When the external port (1-1) is set to four ports, the distances from the center of the dielectric substrate (1-3) are 40 mm, 24 mm, 24 mm and 40 mm respectively.

4. The method of designing a low profile antenna wall of claim 1, wherein, S2 specifically refers to: Firstly, the base function system is selected, and the current distribution on the antenna aperture is expanded by the base function system, and the far field pattern corresponding to the current distribution of the mth characteristic mode is obtained by integrating with the dyadic Green's function : ； in The basis function is used to represent the current distribution corresponding to the m-th characteristic mode. The weight of the expansion For the far-field dyadic Green's function, For solid angles, The source position coordinate vector; For the first Far-field pattern corresponding to each basis function; Based on the power distribution of the incoming wave angle The received voltage at the antenna port is obtained. : ； Based on the received voltage at the antenna port Calculate the covariance matrix of the antenna port voltage. : ； in The power angular spectrum of the incoming wave. The index of the basis function. Number the antenna ports; It is the first p The current distribution corresponding to each characteristic antenna mode is represented by a basis function. Expanded weighted conjugation; Integral expression above for The matrix representation of covariance ; Considering the radiated power normalization condition and the gain constraint condition, using express The Column, then we get: in , Let represent the real part of the impedance matrix of the basis function system. Free-space wave impedance; Directed matrix Introducing heat loss resistor To limit the gain, let , The total power fed to the antenna array, including radiated power and loss power, is expressed as the expansion coefficient matrix. use Calculations are performed to obtain the optimal solution that satisfies the above two conditions. ; in For matrix The largest corresponding eigenvalue decomposition An eigenvector matrix with eigenvalues.

5. The design method for a low-profile antenna wall according to claim 4, characterized in that, The range is from 1 to 121. The range is 1 to 4.

6. The design method for a low-profile antenna wall according to claim 1, characterized in that, S2 specifically refers to: The basis function system is chosen to be a square pulse basis function system, which is expressed as: ； in The rectangular coordinate components of the center of the nth primitive are... .

7. The design method for a low-profile antenna wall according to claim 4, characterized in that, S2 specifically refers to: In S3, the expansion coefficient matrix obtained in S2 is... Substitution In the middle, we get the first The elevation angle of the radiation pattern corresponding to each antenna And the azimuth angle of the antenna pattern .

8. The design method for a low-profile antenna wall according to claim 7, characterized in that, S2 specifically refers to: The specific process of S4 is as follows: Simulation was performed using electromagnetic simulation software. After setting boundary conditions, the surface wave dispersion curve of the impedance element was obtained by using incident wave phase control. The element phase shift at the corresponding frequency point was obtained using the surface wave dispersion curve, and the corresponding impedance was calculated. ； in It is free-space wave impedance. At the speed of light, Let be the side length of the unit. The intrinsic frequency, The calculated impedance is given by j, where j is the imaginary sign and Φx is the tangential dispersion phase. g is the width of the impedance gap; The elevation angle from the antenna pattern And the azimuth angle of the antenna pattern The main lobe distribution of the spatial radiation pattern is obtained, and based on its and From the given values, we can obtain the corresponding beam control formula: ； in The average impedance, For modulation impedance, For free space wavenumber, This is the unit orientation vector. The equivalent refractive index is given, and x and y are the antenna array coordinate parameters of the corresponding impedance element. The spatial multiplexing of the port beam for the antenna array is constructed using the linear superposition relationship.

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