A design method for decoupling surfaces of array antennas based on eigenmode analysis

Abstract

The present invention discloses a method for designing a decoupling surface for an array antenna based on characteristic mode analysis, which belongs to the field of designing decoupling surfaces for array antennas. The method first finds the main cancellation mode through characteristic mode analysis; then, in combination with characteristic mode theory, the position of the decoupling surface and the patch are changed to adjust the amplitude and phase of the main cancellation mode to achieve the decoupling requirement, thereby obtaining a decoupling surface that meets the decoupling requirement. Compared with the current decoupling surface design method based on S parameters, the present method (1) combines the characteristic mode theory for design, making the design direction clearer, thereby reducing the number of optimizations and dependence on experience, and improving design efficiency; (2) by analyzing the characteristic modes of the coupling field and the cancellation field, the main cancellation mode is found, thereby improving the design accuracy and the decoupling effect of the designed decoupling surface. In addition, due to the wide applicability of the characteristic mode theory, the method is suitable for the research and development of decoupling surfaces for various array antennas.

Description

Technical Field

[0001] The present invention belongs to the field of array antenna decoupling surface design. Specifically, it provides a design method for array antenna decoupling surfaces based on eigenmode analysis. This method is applicable to the development of decoupling surfaces for various array antennas. Background Art

[0002] Antenna arrays have the characteristics of electronic scanning and pattern reconstruction, so they have been widely used. However, the coupling between units will seriously affect the performance of the antenna array. Subsequently, people have conducted a lot of research on the decoupling technology of antenna arrays. Common decoupling technologies include defective ground structure and electromagnetic bandgap decoupling structure. However, these methods have limitations: defective ground structure will increase back radiation, and adding electromagnetic bandgap decoupling structure between units is not suitable for compact antenna arrays. In order to find a more effective antenna array decoupling method, in 2017, Professor Wu Keli proposed a new decoupling structure: array antenna decoupling surface. This structure will reflect the radiation field of the antenna to obtain a reflection field, which offsets the coupling field between antenna units, thereby reducing coupling. Subsequently, this decoupling structure has been successfully applied to various types of antenna arrays. However, the current decoupling surfaces are all designed based on S parameters, which (1) leads to a high reliance on experience and optimization, limiting the efficiency of decoupling surface design; (2) they are analyzed at the macro level, and the coupling field and cancellation field modes are not specifically analyzed, so it is not known which cancellation mode plays the main cancellation role. This characteristic results in a low accuracy of this design method, which limits the decoupling effect of the designed decoupling surface. Summary of the Invention

[0003] This invention aims to address the shortcomings of current decoupling surface design methods and proposes a design method for array antenna decoupling surfaces based on eigenmode analysis. This method uses eigenmode analysis to design decoupling surfaces for array antennas. First, the primary cancellation modes are identified through eigenmode analysis. Then, in conjunction with eigenmode theory, the position and patches of the decoupling surface are varied to adjust the amplitude and phase of the primary cancellation modes, achieving the desired decoupling. This results in a decoupling surface that meets these requirements.

[0004] The object of the present invention is achieved like this:

[0005] A method for designing a decoupling surface for an array antenna based on characteristic mode analysis specifically comprises the following steps:

[0006] Step 1: Preliminary design of the decoupling surface of the array antenna. The patches of the decoupling surface of the array antenna are in the form of a combination of multiple rectangular patches, and the arrangement direction of the rectangular patches is consistent with the polarization direction of the antenna.

[0007] Step 2: Use the electromagnetic simulation software FEKO to perform characteristic mode analysis on the coupling field between the array elements to obtain the amplitude and phase of each mode of the coupling field; perform characteristic mode analysis on the cancellation field to obtain the amplitude and phase of each mode of the cancellation field;

[0008] Coupled Field Mode of Quantity set to , cancellation field mode of Quantity set to ;pass ;

[0009] Calculate the degree of cancellation of each mode and find the main cancellation mode; among them, 、 , Representing characteristic patterns , Indicates the field 、 、 Quantity, and They represent the coupled field modes of The amplitude and phase of the components, and Represents the cancellation field mode of The amplitude and phase of the components, Indicates the cancellation field mode of Component-pair coupled field pattern of the degree of cancellation caused by weight;

[0010] Step 3: Change the position of the array antenna decoupling surface and analyze the degree of cancellation after the position change. If the cancellation degree increases, continue to adjust the position in the same direction, otherwise adjust the position in the opposite direction until the antenna decoupling surface position that meets the decoupling requirements is obtained;

[0011] Step 4: The electromagnetic simulation software FEKO is used to simulate and obtain the eigenvalue of the main cancellation mode, and the eigenvalue is used to determine whether the main cancellation mode stores net electric energy or net magnetic energy. Then, the patch on the decoupling surface of the array antenna is modified to change the ability of the main cancellation mode to store net electric energy / net magnetic energy, thereby changing its eigenvalue and reducing the main cancellation mode. ;

[0012] Step 5: Repeat steps 2 to 4 until the decoupling requirements are met.

[0013] Furthermore, in step 2, the amplitude and phase of each mode of the coupling field and the cancellation field are obtained by the following process:

[0014] Step 201, using electromagnetic simulation software FEKO to simulate the coupling field between array elements, and obtain the amplitude and phase of the mode weight coefficient of each mode of the coupling field, and the amplitude and phase of the characteristic field;

[0015] Step 202: Multiply the mode weight coefficient and the amplitude of the characteristic field and add the phase to obtain the amplitude and phase of each mode of the coupling field;

[0016] Step 203, simulating the cancellation field using electromagnetic simulation software FEKO to obtain the amplitude and phase of the mode weight coefficient of each mode of the cancellation field and the amplitude and phase of the characteristic field;

[0017] Step 204: Multiply the amplitudes of the mode weight coefficients and the characteristic fields and add their phases to obtain the amplitudes and phases of each mode of the cancellation field.

[0018] Furthermore, in step 2, during simulation, the coupling field is the radiation field of one unit at another unit; the cancellation field is the reflection field of the radiation field of the antenna unit at the coupled unit after being reflected by the ADS unit.

[0019] Furthermore, in step 2, the cancellation field mode of Component-pair coupled field patterns of The degree of cancellation caused by weight is defined as:

[0020] ;

[0021] in, Coupled field mode of Quantity, Field cancellation mode of Component. The derivation process of this formula: Complex numbers can be expressed as vectors on the complex plane, so the coupled field mode of Component, cancellation field mode of The components can be expressed as vectors on the complex plane. After cancellation, the coupling field is the vector sum of these two vectors. According to the vector synthesis, That is, the amplitude of the coupled field after cancellation; It is defined as the energy ratio of the original coupling field to the coupling field after cancellation, so we get .

[0022] Furthermore, in step 3, the position of the decoupling surface of the array antenna is obtained by the following process:

[0023] Step 301: Change the position of the array antenna decoupling surface and analyze the degree of cancellation of the main cancellation mode after the position change. changes;

[0024] Step 302: If the cancellation degree increases, continue to adjust the position in the same direction; otherwise, adjust the position in the opposite direction.

[0025] Furthermore, in step 4, the patch on the decoupling surface of the array antenna is obtained through the following process:

[0026] Step 401: Using electromagnetic simulation software FEKO to simulate and obtain the eigenvalues of the main cancellation mode, and judging whether the main cancellation mode stores net electric energy or net magnetic energy based on the eigenvalues;

[0027] Step 402: by modifying the patch on the decoupling surface of the array antenna or adding inductance / capacitance elements, the ability of the main cancellation mode to store net electric energy / net magnetic energy is changed, thereby changing its characteristic value, so that the main cancellation mode Decrease.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention proposes a design method for array antenna decoupling surfaces based on eigenmode analysis: first, the main cancellation mode is found through eigenmode analysis; then, combined with eigenmode theory, the position of the decoupling surface and the patch are changed to adjust the amplitude and phase of the main cancellation mode to achieve the decoupling requirements, thereby obtaining a decoupling surface that meets the decoupling requirements. Compared with the traditional design method based on S parameters, this method (1) combines eigenmode theory for design, making the design direction clearer, thereby reducing the number of optimizations and dependence on experience, and improving design efficiency; (2) by analyzing the eigenmodes of the coupling field and the cancellation field, the main cancellation mode is found, thereby improving the design accuracy and enhancing the decoupling effect of the designed decoupling surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is an axonometric diagram of the antenna unit structure.

[0031] Figure 2 A top view of the antenna unit structure.

[0032] Figure 3 This is a side view of the antenna unit structure.

[0033] Figure 4 Schematic diagram of the preliminary designed decoupling surface.

[0034] Figure 5 Schematic diagram of the preliminary designed decoupling surface and the binary array of the preliminarily designed decoupling surface composed of two adjacent units.

[0035] Figure 6 is the coupling field and the cancellation field of each mode Component amplitude.

[0036] Figure 7 is the coupling field and the cancellation field of each mode Component amplitude.

[0037] Figure 8 These are the coupling field, cancellation field, and coupling field after cancellation at different decoupling surface heights.

[0038] Figure 9 To shorten the coupling field before and after the patch spacing, the cancellation field, and the coupling field after cancellation.

[0039] Figure 10 To shorten the decoupling surface patch before and after the gap.

[0040] Figure 11 The 8-element linear array before loading the final decoupling surface.

[0041] Figure 12 This is the 8-element linear array after loading the final decoupling surface.

[0042] Figure 13 Scd before and after loading the decoupling surface for normal radiation.

[0043] Figure 14 Scf before and after loading the decoupling surface for normal radiation.

[0044] Figure 15 Active reflection coefficients of units a, b, c, and d before and after loading the final decoupling surface.

[0045] Figure 16 The array pattern at 2.1 GHz before and after loading the final decoupling surface.

[0046] Figure 17 The array pattern at 2.25 GHz before and after loading the final decoupling surface.

[0047] Figure 18 The array pattern at 2.4 GHz before and after loading the final decoupling surface. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] The present invention first performs eigenmode analysis on the coupling and cancellation fields to identify the primary cancellation mode. Next, the influence of the decoupling surface position on the amplitude and phase of this primary cancellation mode is analyzed, further determining the effect of the decoupling surface position on the cancellation effect. The decoupling surface position is designed based on the analysis results. Next, combining eigenmode theory, the influence of the patch on the amplitude and phase of the primary cancellation mode is analyzed to determine the effect of the patch on the cancellation effect. The patch design is then based on the analysis results. Ultimately, a decoupling surface that meets the decoupling requirements is obtained.

[0050] A method for designing a decoupling surface for an array antenna based on characteristic mode analysis comprises the following steps:

[0051] Step 1: Preliminary design of the antenna array decoupling surface. The decoupling surface of the antenna array is composed of multiple rectangular patches, and the arrangement direction of the rectangular patches is consistent with the polarization direction of the antenna.

[0052] Step 2, use characteristic mode analysis to find the main cancellation mode. Use the electromagnetic simulation software FEKO to simulate and obtain the amplitude and phase of the mode weight coefficient of each mode of the coupling field, and the amplitude and phase of the characteristic field. Then, multiply the amplitudes of the two and add the phases to obtain the amplitude and phase of each mode of the coupling field. Use the electromagnetic simulation software FEKO to simulate and obtain the amplitude and phase of the mode weight coefficient of each mode of the cancellation field, and the amplitude and phase of the characteristic field. Then, multiply the amplitudes of the two and add the phases to obtain the amplitude and phase of each mode of the cancellation field. Calculate the degree of cancellation of each mode , find the main cancellation patterns;

[0053] Step 3: Design the position of the array antenna decoupling surface. Change the position of the array antenna decoupling surface and analyze the degree of cancellation of the main cancellation modes after the position change. If the cancellation degree increases, continue to adjust the position in the same direction, otherwise adjust the position in the opposite direction;

[0054] Step 4: Design of the decoupling surface patch of the array antenna. First, the eigenvalue of the main cancellation mode is obtained by FEKO simulation using the electromagnetic simulation software. Based on the eigenvalue, it is determined whether the main cancellation mode stores net electric energy or net magnetic energy. Then, by modifying the patch of the decoupling surface of the array antenna, adding inductor / capacitor elements, etc., the ability of the main cancellation mode to store net electric energy / net magnetic energy is changed, thereby changing its eigenvalue so that the main cancellation mode stores net electric energy / net magnetic energy. reduce;

[0055] Step 5: After completing the above steps, if further coupling reduction is required, repeat steps 2 to 4 until the coupling reduction requirements are met.

[0056] The following is a specific example of designing a decoupling surface for an array antenna:

[0057] The structure of the selected antenna unit is as follows Figures 1 to 3 As shown, the dimensions are W=L=65mm, Wp=Lp=42.5mm, W1=21.7mm, L1=1.8mm, W2=4mm, L2=8mm, R=1.3mm, R1=2.17mm, H1=13mm, H2=4mm, H3=1mm, H4=23.09mm. The operating frequency range of the antenna is 2GHz to 2.5GHz. The preliminary designed array antenna decoupling surface consists of a dielectric plate and four rectangular patches arranged along the polarization direction of the antenna. The size of each patch is 15mm×15mm, and the height of the decoupling surface is set to 19mm, as shown in Figure 1. Figure 4 shown.

[0058] Next, we use the characteristic mode analysis to find the main cancellation mode. Because the coupling between adjacent units is much greater than the coupling between non-adjacent units, we study two adjacent antenna units, which are set as unit a and unit b, as shown in the following example: Figure 5 According to the electromagnetic field boundary conditions, the coupling of the antenna unit is the coupling field Quantity, The components are generated, so only the Quantity, Component. (1) At 2.32GHz, the electromagnetic simulation software FEKO is used to perform characteristic mode analysis on the coupling field of adjacent units. The coupling field selected in the simulation is the radiation field of unit a at unit b. The simulation obtains the amplitude and phase of the mode weight coefficient of each mode of the coupling field, and the amplitude and phase of the characteristic field. Then, the amplitudes of the two are multiplied and the phases are added to obtain the amplitude and phase of each mode of the coupling field. The amplitude is as follows: Figure 6 As shown. (2) At 2.32GHz, the electromagnetic simulation software FEKO is used to perform characteristic mode analysis on the cancellation field. The cancellation field selected in the simulation is the reflected field at the element b obtained by the radiation field of the decoupling surface unit reflection unit a. Using the same method as the coupling field characteristic mode analysis, the amplitude and phase of each mode of the cancellation field are obtained. The amplitude is shown in Figure 7 As shown. (3) According to Figure 6 and Figure 7 It can be seen that the coupling between adjacent units is mainly caused by the modes a, b, c, d, and e of the coupling field. Combining the amplitudes of each mode of the cancellation field, it can be seen that the cancellation is mainly caused by the mode a of the coupling field. Components and cancellation fields of mode a Therefore, the main cancellation effect is the cancellation field mode a Quantity.

[0059] Next, the position of the decoupling surface of the array antenna is designed. The height of the decoupling surface is changed to 23 mm, and the same method as step 2 is used to calculate the cancellation field mode a after the height is changed. The amplitude and phase of the components are shown in Table 1. Component, coupled field mode a Components, coupled fields after cancellation The components are expressed in the complex plane as Figure 8 As shown in Table 1 and Figure 8 , the cancellation degree increases after increasing the height, so the height of the decoupling surface is further adjusted in the direction of increase. Adjust the height of the decoupling surface to 27mm, and cancel the The amplitude and phase of the components, the degree of cancellation, and the magnitude of coupling reduction are shown in Table 1. It can be seen that the degree of cancellation and the magnitude of coupling reduction are further increased, with the degree of cancellation increasing from 7.99% to 12.05% and the magnitude of coupling reduction increasing from 6.22 dB to 9.21 dB.

[0060] Table 1. Cancellation mode a at different heights The amplitude and phase of the components, the degree of cancellation and decoupling

[0061]

[0062] Then, the array antenna decoupling surface patch design is carried out. Considering the cross-sectional height of the antenna, the height of the decoupling surface is selected as 23mm. The eigenvalue of the cancellation mode a is obtained through simulation =-44.06, which is less than 0, so the cancellation mode a stores net electrical energy. The gaps between the metal patches on the decoupling surface act as energy storage, so shortening these gaps can reduce the energy storage capacity of the cancellation mode a, thereby reducing the net energy storage capacity of the cancellation mode a, and thus reducing .

[0063] According to the characteristic mode theory, ; ; ; ,in, It is a cancellation mode The mode weight coefficient of yes Phase; It is a cancellation mode The corresponding characteristic magnetic field So, there is

[0064] ;

[0065] ;

[0066] therefore, Smaller Increase and thus Increase; is less than 0, so Becoming smaller Get smaller, Smaller Becoming smaller and causing Therefore, shortening the patch gap will increase , reduce Through simulation and calculation, we can get 、 , so shortening the patch gap will lead to the cancellation of field mode a Component and coupled field mode a The angle between the components increases. The cancellation field pattern a before and after the gap will be shortened. Component, coupled field mode a Components, coupled fields after cancellation The components are expressed in the complex plane as Figure 9 As shown. Figure 9 It can be seen that the degree of cancellation is improved after shortening the gap. In this example, the patch length is changed from 15mm×15mm to 15mm×12mm, and a narrow metal strip is added in the gap between the patches, such as Figure 10 Through simulation, it is found that the degree of decoupling increases from 6.22dB to 8.85dB after shortening the gap.

[0067] The final designed array antenna decoupling surface is loaded on the eight-element linear array composed of antenna units to verify the proposed method. The eight-element linear array before and after loading is as follows: Figure 11 and Figure 12 shown.

[0068] First, the coupling reduction during normal radiation, the change in antenna matching, and the change in array radiation pattern are studied.

[0069] (1) Coupling reduction during normal radiation. Mutual coupling is divided into mutual coupling between adjacent units and mutual coupling between non-adjacent units. Adjacent units select units c and d, and non-adjacent units select units c and f. During normal radiation, Scd and Scf before and after loading the designed coupling reduction surface are obtained through HFSS simulation, as shown in the following figure: Figure 13 and Figure 14As shown in the figure, when radiating in the normal direction, Scd decreases by a maximum of 28.56dB within the frequency band, and Scf decreases by 1.7dB to 7.61dB within the frequency band. This shows that the coupling between adjacent units and non-adjacent units is effectively reduced when radiating in the normal direction.

[0070] (2) The matching changes of the antenna during normal radiation. Units e, f, g, h are symmetrical with units a, b, c, d, so units a, b, c, d can be selected for simulation. During normal radiation, the active reflection coefficients of units a, b, c, d before and after loading the designed decoupling surface are as follows: Figure 15 As shown, it can be seen that the active reflection coefficients of units a, b, c, and d within the frequency band are lower than -12.5 dB after loading the designed decoupling surface, indicating that the antenna is well matched after loading.

[0071] (3) Changes in the array pattern during normal radiation. When the array operates at 2.1GHz, 2.25GHz, and 2.4GHz and is radiating normally, the array pattern before and after loading the designed decoupling surface is as follows: Figures 16 to 18 As shown in the figure, at 2.1 GHz, the array gain decreased from 14.59 dB to 14.48 dB after the decoupling surface was added, a decrease of 0.11 dB. At 2.25 GHz, the array gain decreased from 15.04 dB to 14.94 dB after the decoupling surface was added, a decrease of 0.1 dB. At 2.4 GHz, the array gain increased from 15.27 dB to 15.47 dB after the decoupling surface was added, an increase of 0.2 dB. It can be seen that the array pattern within the frequency band remains basically unchanged after the decoupling surface was added.

[0072] Next, the decoupling and antenna matching during scanning are studied.

[0073] It can be used to characterize the strength of the total coupling received by port m, where is the active reflection coefficient of port m, is the passive reflection coefficient of port m. When the antenna works at 2.32GHz, the antenna under different scanning angles is 、 As shown in Table 2. According to Table 2, it can be seen that: (1) When the scanning angle is -50 degrees, -30 degrees, 0 degrees, 30 degrees, and 50 degrees, the designed decoupling surface reduces , indicating that the designed decoupling surface can play a role in suppressing coupling during the scanning process; (2) As the scanning angle increases This is because the increase in scanning angle will lead to an increase in coupling and thus a deterioration in matching. After loading the designed decoupling surface, The increase in the value of the antenna array is greatly reduced and is lower than that of the original antenna array when scanning at large angles. , so the decoupling surface can improve the antenna matching deterioration problem caused by scanning. (3) When scanning at a large angle (±50 degrees), after loading the designed decoupling surface, It is less than -10dB, while the original antenna is greater than -6dB. Therefore, the designed decoupling surface greatly improves the matching during large-angle scanning.

[0074] Table 2. At 2.32 GHz, the decoupling surface is loaded before and after the design, and the scanning angles are different. 、 ;

[0075] .

[0076] Combining the above results, we can see that (1) during normal radiation, after loading the designed decoupling surface, the Scd decreases by a maximum of 28.56 dB and the Scf decreases by a maximum of 7.61 dB within the frequency band. The coupling is effectively suppressed regardless of whether it is adjacent or non-adjacent units; (2) the designed decoupling surface can play a role in suppressing mutual coupling during the scanning process, and can also improve the matching deterioration problem caused by scanning and the matching situation during large-angle scanning.

[0077] The present invention first finds the main cancellation mode through characteristic mode analysis. Then, combined with characteristic mode theory, the position of the decoupling surface and the patch are changed to adjust the amplitude and phase of the main cancellation mode to achieve the decoupling requirements, and a decoupling surface that meets the decoupling requirements is obtained. Compared with the traditional S-parameter-based array antenna decoupling surface design method, this method (1) combines the characteristic mode theory for design, making the design direction clearer, thereby reducing the number of optimizations and dependence on experience, and improving design efficiency; (2) by analyzing the characteristic modes of the coupling field and the cancellation field, the main cancellation mode is found, thereby improving the design accuracy and enhancing the decoupling effect of the designed decoupling surface.

[0078] It should be noted that the above description is only a preferred application example of the present invention and is not intended to limit the scope of protection of the present invention. Any technical solution that adopts equivalent replacement or equivalent transformation is within the scope of protection of the present invention.

Claims

1. A method for designing decoupling surfaces for array antennas based on characteristic mode analysis, characterized in that: The specific steps include: Step 1: Preliminary design of the array antenna decoupling surface; The patches on the decoupling surface of the array antenna are in the form of a combination of multiple rectangular patches, and the arrangement direction of the rectangular patches is consistent with the polarization direction of the antenna; Step 2: Use the electromagnetic simulation software FEKO to perform characteristic mode analysis on the coupling field between the array elements to obtain the amplitude and phase of each mode of the coupling field; perform characteristic mode analysis on the cancellation field to obtain the amplitude and phase of each mode of the cancellation field; Coupled Field Mode of Quantity set to , cancellation field mode of Quantity set to ;pass ； Calculate the degree of cancellation of each mode and find the main cancellation mode; among them, 、 , Representing characteristic patterns , Indicates the field 、 、 Quantity, and They represent the coupled field modes of The amplitude and phase of the components, and Represents the cancellation field mode of The amplitude and phase of the components, Indicates the cancellation field mode of Component-pair coupled field pattern of the degree of cancellation caused by weight; Step 3: Change the position of the array antenna decoupling surface and analyze the degree of cancellation after the position change. If the cancellation degree increases, continue to adjust the position in the same direction, otherwise adjust the position in the opposite direction until the antenna decoupling surface position that meets the decoupling requirements is obtained; Step 4: The electromagnetic simulation software FEKO is used to simulate and obtain the eigenvalue of the main cancellation mode, and the eigenvalue is used to determine whether the main cancellation mode stores net electric energy or net magnetic energy. Then, the patch on the decoupling surface of the array antenna is modified to change the ability of the main cancellation mode to store net electric energy / net magnetic energy, thereby changing its eigenvalue and reducing the main cancellation mode. ; Step 5: Repeat steps 2 to 4 until the decoupling requirements are met.

2. The method for designing a decoupling surface for an array antenna based on characteristic mode analysis according to claim 1, wherein: In step 2, the amplitude and phase of each mode of the coupling field and the cancellation field are obtained by the following process: Step 201, using electromagnetic simulation software FEKO to simulate the coupling field between array elements, and obtain the amplitude and phase of the mode weight coefficient of each mode of the coupling field, and the amplitude and phase of the characteristic field; Step 202: Multiply the mode weight coefficient and the amplitude of the characteristic field and add the phase to obtain the amplitude and phase of each mode of the coupling field; Step 203, simulating the cancellation field using electromagnetic simulation software FEKO to obtain the amplitude and phase of the mode weight coefficient of each mode of the cancellation field and the amplitude and phase of the characteristic field; Step 204: Multiply the amplitudes of the mode weight coefficients and the characteristic fields and add their phases to obtain the amplitudes and phases of each mode of the cancellation field.

3. The method for designing a decoupling surface for an array antenna based on characteristic mode analysis according to claim 1, wherein: In step 2, during simulation, the coupling field is the radiation field of one unit at another unit; the cancellation field is the reflection field of the radiation field of the antenna unit at the coupled unit after being reflected by the ADS unit.

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