Phased-array antenna scattering surface custom control method and system based on impedance modulation

Abstract

The invention discloses a self-defined control method and system for a scattering surface of a phased-array antenna based on impedance modulation, and mainly solves the problem that the scattering characteristic of the phased-array antenna cannot be accurately controlled in the prior art. According to the implementation scheme, the method comprises the following steps: collecting a to-be-solved linear array antenna; calculating an array antenna mode item scattering field under any load by using each unit radiation field in the array, and calculating an array total scattering field and an antenna total scattering field RCS value according to the scattering field and the structure mode item scattering field; constructing a fitness function containing deviation between a target value and an actual scattering value, and iteratively optimizing non-uniform terminal impedance of an array antenna mode item scattering field; and the optimized terminal impedance value is utilized to change a load reflection matrix in an antenna mode item scattering field to modulate the antenna mode item scattering field so as to offset the structure mode scattering field, so that the total scattering field RCS reaches a specified target value, and the impedance is utilized to design an antenna array comprising an impedance matching network. The method can achieve the precise control of the scattering characteristics of the phased-array antenna, and can be used for the control of the radar cross section.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic technology, and specifically relates to a precise and customizable scattering control method and system, which can be used for the control of radar cross section. Background Technology

[0002] Radar cross section (RCS) reduction technology has attracted much attention in equipment such as warships, aircraft, and missiles due to its outstanding stealth performance. As a key device that simultaneously radiates and scatters electromagnetic waves, the antenna array makes a significant contribution to the overall RCS characteristics. How to reduce the RCS of phased arrays while maintaining radiation performance is a research focus. The total scattered field of an antenna includes the structural mode scattered field and the antenna mode scattered field. Traditional methods for suppressing the scattered field of structural modes, such as reducing the metal structure, applying bandpass frequency selective surfaces (FSS), and using electromagnetic absorbers, have been widely used in stealth radome design, but they all have problems such as limited effectiveness, deterioration of radiation performance, or increase in antenna size. As for the suppression of the antenna mode scattered field, it is more difficult to suppress because it is generated by secondary radiation caused by mismatch at the antenna back end. Moreover, the space of the antenna back end structure is limited, making it difficult to effectively modify. In addition, the reciprocity of the antenna means that the antenna mode scattered field will inevitably be generated in the operating frequency band, and its impact on the antenna stealth performance is comparable to that of the structural mode scattered field. Although existing matching network designs can reduce the amplitude of the antenna mode scattered field, they face challenges such as design complexity and the need for additional transmission paths. Furthermore, it is difficult to achieve minimum in-band scattering by a single suppression structure mode or antenna mode scattering field. If multiple methods are combined, it is easy to cause problems such as complex structure, low control accuracy and increased cost.

[0003] Patent document CN202111242709.9 discloses "An In-Band Scattering Reduction Structure and Control Method Based on a Four-Dimensional Antenna Array," which achieves in-band RCS reduction of a phased array antenna by randomly rotating the array elements around the feed point. Specifically, when each array element of the phased array antenna randomly rotates around the feed point, the physical attitude of the array element changes, causing the phase of its scattered electromagnetic waves to change randomly. In the far-field region, the scattered fields of different array elements are difficult to achieve in-phase superposition in the direction of the radar detection main lobe due to the random phase distribution, thus effectively reducing the radar cross section of the antenna in that direction. At the same time, to ensure that the radiation performance is not affected, this scheme compensates for the phase deviation caused by the rotation of the array elements by adjusting the excitation phase of the array elements, ensuring that the radiated beam can still point to the target direction, achieving a preliminary balance between RCS reduction and radiation performance maintenance. However, this method has the following three shortcomings:

[0004] Firstly, due to the special properties of circularly polarized antenna elements, the polarization direction and phase distribution are changed through rotation. Therefore, effective RCS reduction cannot be achieved for other types of antenna elements such as linearly polarized and elliptically polarized antennas whose polarization characteristics are incompatible with the rotation mechanism, which greatly limits the application scope of this technology.

[0005] Secondly, this scheme only considers the ideal case of an infinite array in terms of array model, and conducts theoretical derivation and performance analysis based on periodic boundary conditions and uniform plane wave illumination assumptions. However, the phased array antennas in actual engineering are all finite arrays, which have problems such as edge effects and increased mutual coupling effects. Therefore, the scattering characteristics of finite arrays are significantly different from those of infinite arrays.

[0006] Third, because the scheme does not specifically design and optimize the boundary cells and edge regions of the finite large array, it is difficult to accurately control the scattering distribution of the actual array, and the overall RCS suppression effect of the finite large array is limited, which cannot meet the engineering application requirements in complex electromagnetic environments. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and propose a precise custom method and system for phased array antenna scattering based on impedance modulation. This method balances radiation performance with the mutual coupling between components, improves the overall RCS suppression effect of a finite large array, and precisely controls the total scattering field of the antenna to a specified value at the required angle or angular domain while maintaining radiation performance, thereby achieving precise control of the scattering characteristics of the phased array antenna.

[0008] The technical approach to achieving the objective of this invention is as follows: by establishing an analytical relationship between the array radiation field, the antenna mode term scattering field, and the structure mode term scattering field, the antenna mode term scattering field is modulated to cancel the structure mode term scattering field based on the analytical formula, so as to achieve customization of the total antenna scattering field; by designing a non-uniform terminal impedance network corresponding to the modulated antenna mode term scattering field, the control of the total scattering field and port matching are achieved.

[0009] Based on the above ideas, the technical solution of the present invention includes the following:

[0010] 1. A method for customizing the scattering surface of a phased array antenna based on impedance modulation, characterized in that it includes:

[0011] (1) Obtain the S-parameter matrix [S] of the N-element linear array antenna to be solved. NN Scattering field of structural mode terms and the radiation field in each unit array θ is the pitch angle in the measurement space rectangular coordinate system, and φ is the azimuth angle in the measurement space rectangular coordinate system;

[0012] (2) Utilizing the radiation field of each unit in the array Calculate the scattered field of the array antenna mode terms under arbitrary load.

[0013] (3) Based on the scattering field of the array antenna mode term Scattering field with structural mode term Calculate the total scattered field E of the array s (θ,φ) and the RCS value of the total scattered field of the antenna;

[0014] (4) Specify the angle or angle domain for reducing scattering, define the target value σ of the total scattering field RCS at the desired angle or angle domain, and construct a fitness function that includes the deviation between the target value and the actual scattering value.

[0015] (5) Use intelligent optimization algorithms and an elite retention strategy to iteratively optimize the non-uniform terminal impedance of the scattering field of the mode term of the array antenna until the predefined maximum number of iterations is reached.

[0016] (6) Using the optimized non-uniform terminal impedance value, change the load reflection matrix [Γ] in the antenna mode term scattered field. NN The antenna mode scattering field is modulated to cancel the structure mode scattering field, so that the total scattering field RCS reaches the specified target value σ, thereby achieving precise customization of the total scattering field.

[0017] (7) Calculate the transmission line length of the impedance matching network based on the optimized non-uniform termination impedance. and parallel single branch length And design an antenna array that includes an impedance matching network.

[0018] Furthermore, the construction of the fitness function, which includes the deviation between the target value and the actual scattering value, is implemented by:

[0019] Based on the RCS value σ of the total scattered field of the antenna s (θ s ,φ), when the RCS of the total scattered field is at a specified incident angle θ s During scaling down, the fitness function is defined as follows:

[0020]

[0021] Based on the RCS value σ of the total scattered field of the antenna s (θ s When the RCS of the total scattered field decreases within the specified angular domain a ≤ s ≤ b, the fitness function is defined as follows:

[0022]

[0023] Given that the antenna mode term of each array element needs to be propagated twice through the back-end transmission line and its phase needs to be controlled by adding a delay line, the total scattered field of the array is... Represented as:

[0024]

[0025] Adjusting the additional phase φ and load resistance Z l To achieve control over the total scattered field E of the antenna s (θ,φ) control, using load resistance and additional phase as optimization variables, when the RCS of the total scattered field is within the specified angular domain θ a ≤θ s ≤θ b When reducing the internal size, the RCS value σ of the total scattered field of the antenna is used. s (θ s The fitness function is defined as follows:

[0026]

[0027] In the formula θ a and θ b These are the upper and lower boundaries of the sampling angle domain, θ d Let K be the sampling angle, K be the number of sampling angles in the entire angle domain, and σ be the sampling angle. s (θ s ,φ) is the total RCS of the phased array at the sampling angle, and σ(dBsm) is the defined target value.

[0028] Furthermore, the optimized non-uniform termination impedance value Z is used... ln , change the load reflection matrix [Γ] in the scattered field of the antenna mode term NN The modulation of the antenna mode scattering field, its implementation includes:

[0029] When the array is in receiving mode, according to the non-uniform termination impedance value Z ln Determine the load reflection coefficient Γ of the nth element. n ;

[0030] Using the load reflection coefficient Γ of each unit n The load reflection coefficient matrix is ​​composed of: [Γ] NN =diag[Γ1,Γ2...Γ] n ...Γ N ];

[0031] Once the array antenna configuration is fixed, the radiation field of each element, the S-parameter matrix representing mutual coupling, and the matched reception vector are all determined. Only the load reflection coefficient matrix [Γ] remains. NN Uncertain properties alter the load reflection matrix [Γ] in the scattered field of the antenna mode term. NN The terminal load Z of each element for each load reflection coefficient ln This is done by controlling the change in the scattered field of the antenna mode terms of the array, thereby modulating the scattered field of the antenna mode.

[0032] Furthermore, the design includes an antenna array with an impedance matching network, based on the transmission line electrical length. and parallel single-branch electrical length Determine the transmission line length and parallel single stub length of each unit impedance matching network to match the input impedance with the termination impedance, and print it on the back of the antenna array to ensure that the scattering field of the structural mode terms is not affected.

[0033] 2. A custom control system for the scattering surface of a phased array antenna based on impedance modulation, characterized in that it comprises:

[0034] The parameter acquisition module is used to acquire the S-parameter matrix, the scattering field of the structural mode term, and the radiation field in each element of the N-element linear array antenna to be solved.

[0035] The scattered field calculation module is used to establish the analytical relationship between the array radiation field, the antenna mode scattered field, the structure mode scattered field, and the total scattered field.

[0036] The function building module is used to create the objective function so that the optimization iteration process eventually converges to a solution that meets the objective.

[0037] The impedance optimization module is used to combine the optimized non-uniform load impedances to effectively reduce the total field RCS of the array to the expected value at the target angle or angular domain.

[0038] The scattering field modulation module is used to cancel the scattering field of the antenna mode terms modulated by the load reflection matrix with the scattering field of the structure mode terms, thereby reducing the RCS of the total array scattering field at the target angle or in the angular domain.

[0039] The antenna array design module is used to design antenna matching networks and achieve target scattering reduction.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] Firstly, this invention establishes an analytical relationship between the array radiation field, the antenna mode term scattering field, and the structure mode term scattering field. By modulating the antenna mode term scattering field to cancel the structure mode term scattering field, it can precisely control the scattering to a preset target value within a specified angle or angle domain through accurate design of the antenna's structural parameters and excitation mode. In achieving this goal, theoretical analysis and simulation verification show that the radiation gain only decreases slightly, and the change is within an acceptable engineering range. This indicates that the invention effectively balances the contradiction between scattering control and radiation performance, providing reliable technical support for antenna systems in complex electromagnetic environments and enabling customized control of the total antenna scattering field.

[0042] Secondly, because the present invention constructs a mathematical model containing multiple parameter variables, it can still show good effectiveness when the numerical difference between the scattering field of the structure mode term and the scattering field of the antenna mode term reaches a significant order of magnitude. Experiments show that the present invention can stably achieve the expected scattering control target when dealing with scattering metrics with large order of magnitude differences, overcoming the limitations of traditional methods under such extreme conditions.

[0043] Thirdly, because the present invention designs a non-uniform terminal impedance network corresponding to the scattering field of the modulated antenna mode terms, there is no need to add complex structural components or auxiliary devices around the antenna body. Through the optimized design and performance mining of the antenna's own structure, the total scattering field control and port matching can be successfully achieved while ensuring the original physical size of the antenna, thereby improving the expected function. At the same time, this design concept is not only conducive to the miniaturization and integration of antennas, but also reduces the complexity and manufacturing cost of the antenna system. Attached Figure Description

[0044] Figure 1 This is a flowchart illustrating the implementation of the custom control method for the scattering surface of a phased array antenna based on impedance modulation according to the present invention.

[0045] Figure 2 This is a structural diagram of the 8-element microstrip array antenna designed in the method of this invention;

[0046] Figure 3 This is a block diagram of the custom control system for the scattering surface of the phased array antenna based on impedance modulation according to the present invention.

[0047] Figure 4 The figures show a comparison of the single-station RCS of the reference array, the ideal optimized load impedance array, and the impedance matching network array of this invention at an incident angle of 0°.

[0048] Figure 5 The graphs show a gain comparison between the reference array and the impedance matching network array of this invention at a 0° incident angle.

[0049] Figure 6 The figures show a comparison of the single-station RCS of the reference array, the ideal optimized load impedance array, and the load impedance matching network array of the present invention at an oblique incidence of -22°.

[0050] Figure 7 The graphs show a gain comparison between the reference array and the impedance matching network array of the present invention at an oblique incidence of -22°.

[0051] Figure 8 The images show a comparison of the monostation RCS of the reference array and the ideal optimized array with additional phase and load resistors at an incident angle of 22°.

[0052] Figure 9The images show a comparison of the single-station RCS of the reference array and the impedance matching network array of the present invention at an incident angle of 22°.

[0053] Figure 10 This is a gain diagram of the impedance matching network array of the present invention when the incident angle is obliquely 22°.

[0054] Figure 11 The figures show a comparison of the single-station RCS when the RCS decreases across the entire angular domain, for the reference array and the ideal optimized load-added phase and load resistor arrays, respectively.

[0055] Figure 12 The figures show a comparison of the single-station RCS of the reference array and the impedance matching network array of the present invention when the RCS decreases throughout the entire angular domain.

[0056] Figure 13 The figures show the gain of the reference array and the impedance matching network array of this invention as the RCS decreases over the entire angular domain. Detailed Implementation

[0057] To enable those skilled in the art to better understand the present invention, the technical solutions and effects of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the present invention and not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative effort should all fall within the protection scope of the present invention.

[0058] Example 1: Custom Control Method for Scattering Surface of Phased Array Antenna Based on Impedance Modulation

[0059] Reference Figure 1 The implementation steps of this example include the following:

[0060] Step 1: Acquire the S-parameter matrix [S] from the N-element linear array antenna to be solved. NN Scattering field of structural mode terms and the radiation field in each unit array

[0061] Reference Figure 2This example uses a microstrip patch antenna array. The patch is printed on the top of the upper substrate with a height of 1.016 mm, and the microstrip line (MSL) is printed on the bottom of the lower substrate with a height of 0.254 mm. The design uses a GNC350T dielectric substrate with a relative permittivity of 3.5 and a loss tangent of 0.0025. The two substrates are bonded together with a prepreg layer of 2.76 relative permittivity and a loss tangent of 0.0018, with a thickness of 0.113 mm. The reference antenna resonates at 10 GHz, and the simulated -10 dB impedance bandwidth is 9.76–10.24 GHz.

[0062] An 8-element microstrip patch linear array is used, with a unit spacing of 13mm. The sampling of its radiation and scattering field data requires a scanning method for regional sampling.

[0063] Existing scanning methods include planar scanning, cylindrical scanning, and spherical scanning. Existing scanning areas include near-field, quasi-far-field, and far-field. This embodiment selects, but is not limited to, planar scanning as the scanning method, and the sampling area is not limited to, the far-field. The parameters are collected as follows:

[0064] Each port is connected to a 50-ohm matched load. Simulating this 8-element microstrip antenna array, with the excitation amplitude of each element set to 1 and the other elements set to 0, the resulting total array field is the radiated field of each element. Where θ is the pitch angle in the measurement space rectangular coordinate system, and φ is the azimuth angle in the measurement space rectangular coordinate system;

[0065] S-parameter matrix [S] NN It can be extracted directly from the simulation software;

[0066] Based on the theory that the scattering field of the structural mode term of an 8-element linear array is equal to the total scattering field of the array when each port is connected to a 50-ohm matched load, the scattering field of the linear array when each port is connected to a 50-ohm load can be calculated using HFSS simulation, and the field data can be extracted as the scattering field of the structural mode term of an arbitrary load array.

[0067] Step two, utilizing the radiation fields of each unit in the array Calculate the scattered field of the array antenna mode terms under arbitrary load.

[0068] 2.1) Based on the radiation field of each unit The electric field vector matrix is ​​obtained as follows:

[0069]

[0070] 2.2) When the array is in receiving mode, define the load reflection coefficient Γ of the nth element. n for:

[0071]

[0072] Z ln Z0 is the load impedance of the nth element in the array, and Z0 is the characteristic impedance of the transmission line.

[0073] 2.3) According to the reciprocity theorem, the antenna mode term scattering field of the array It can be calculated as follows:

[0074]

[0075] Among them [E] r (θ,φ)] 1×N Let [Γ] be the electric field vector matrix. NN =diag[Γ1,Γ2...Γ] n ...Γ N [I] represents the load reflection coefficient matrix for each unit. NN Let [S] be the identity matrix. NN To characterize the mutually coupled S-parameter matrices, To match the received vector.

[0076] Step 3: Utilizing the scattered field of the array antenna mode term Scattering field with structural mode term Calculate the total scattered field E of the array s (θ,φ) and the RCS value of the total scattered field of the antenna.

[0077] 3.1) Scattering field of structure mode terms Scattered field with antenna mode term By performing vector superposition, the total scattered field E of the antenna is obtained. s (θ,φ):

[0078]

[0079] 3.2) Based on the total scattered field E of the antenna s (θ,φ) Calculate the RCS of the total scattered field of the antenna σ s (θ,φ):

[0080]

[0081] Where R is the distance between the target and the receiver, and E i (θ,φ) is the electric field of the scattered wave at the target.

[0082] Step 4: Construct a fitness function that includes the deviation between the target value and the actual scattering value.

[0083] 4.1) Specify the angle or angle domain used to reduce scattering, and define the target value σ of the total scattered field RCS at the desired angle or angle domain;

[0084] 4.2) Based on the RCS value σ of the total scattered field of the antenna s (θ s ,φ) and the defined target value σ, when the RCS of the total scattered field is at a specified incident angle θ s During scaling down, the fitness function is defined as follows:

[0085]

[0086] Where θ s Let σ(dBsm) represent the desired angle of incidence. s The defined value of the total scattered field RCS, where P is the number of sampling angles, and Z is the total scattered field RCS. ln =R n +jX n R is the terminal impedance of the unit. n X represents resistance. n Indicates reactance;

[0087] 4.3) Based on the RCS value σ of the total scattered field of the antenna s (θ s Given the defined target value σ, and the RCS of the total scattered field decreases within the specified angular domain a ≤ s ≤ b, the fitness function is defined as follows:

[0088]

[0089] In the formula, a and b are the upper and lower boundaries of the sampling angle domain, respectively. When a = 1 and b = N, the desired angle domain covers the entire angle domain.

[0090] 4.4) Considering that the phase of each array element's antenna mode term needs to be controlled by adding a delay line after propagating twice through the back-end transmission line, the total scattered field of the array is... Represented as:

[0091]

[0092] In the formula To add phase excitation, Z l Z is the load resistance, and Z0 is the characteristic impedance of the transmission line. For the scattering field of the structure mode term, The scattered field of the array antenna mode term;

[0093] 4.5) Adjusting the additional phase and load resistance Z l To achieve control over the total scattered field E of the antenna s(θ,φ) control, using load resistance and additional phase as optimization variables, when the RCS of the total scattered field is within the specified angular domain θ a ≤θ s ≤θ b When reducing the internal size, the RCS value σ of the total scattered field of the antenna is used. s (θ s Given the defined target value σ, the fitness function is defined as follows:

[0094]

[0095] In the formula θ a and θ b These are the upper and lower boundaries of the sampling angle domain, θ d Let K be the sampling angle, K be the number of sampling angles in the entire angle domain, and σ be the sampling angle. s (θ s ,φ) is the total RCS of the phased array at the sampling angle, and σ is the defined target value.

[0096] Step 5: Use intelligent optimization algorithms and an elite retention strategy to iteratively optimize the non-uniform terminal impedance of the array antenna mode term scattering field until the predefined maximum number of iterations is reached.

[0097] Existing typical strategies include elite retention, global replacement, steady-state replacement, shared fitness, and migration strategies. The optimization algorithm strategy in this embodiment adopts, but is not limited to, the elite retention strategy, the implementation of which includes:

[0098] 5.1) Generate initial particles, set the number of particles, randomly initialize the velocity and position of each particle, and generate the i-th particle in the p-th iteration. in It is the terminal load impedance of the nth element of the i-th particle in the P-th iteration. When the particle is initialized, p = 1.

[0099] 5.2) For each particle's load impedance value, calculate its corresponding fitness function value. Based on the calculation results and the termination condition (maximum number of iterations), determine whether to terminate the optimization process.

[0100] If the termination condition is met, output the current optimal solution directly and execute 5.4).

[0101] Otherwise, based on the particle's historical best position and the group's best position, adjust the particle's search direction and step size, update the particle, and execute 5.3).

[0102] 5.3) For the updated particles, recalculate their corresponding fitness function values, compare the fitness function values ​​before and after the update, and select the particle positions that are closer to the optimization target as the optimal positions of the population.

[0103] 5.4) When the iteration meets the termination condition, the optimal non-uniform terminal load impedance corresponding to the optimal position of the output group is output. This parameter is the optimal solution obtained by the optimization algorithm and can be used to guide the actual antenna design.

[0104] Step Six: Using the optimized non-uniform terminal impedance value, change the load reflection matrix [Γ] in the antenna mode term scattered field. NN The antenna mode scattering field is modulated to cancel the structure mode scattering field, so that the total scattering field RCS reaches the specified target value σ, thereby achieving precise customization of the total scattering field.

[0105] 6.1) When the array is in receiving mode, according to the non-uniform termination impedance value Z ln Define the load reflection coefficient Γ of the nth element. n for:

[0106]

[0107] Z ln Z0 is the load impedance of the nth element in the array, and Z0 is the characteristic impedance of the transmission line.

[0108] 6.2) Utilizing the load reflection coefficient Γ of each unit n The load reflection coefficient matrix is ​​composed of: [Γ] NN =diag[Γ1,Γ2...Γ] n ...Γ N ];

[0109] 6.3) Once the array antenna configuration is fixed, the radiation field in each element, the S-parameter matrix representing mutual coupling, and the matched receiver vector are all determined. Only the load reflection coefficient matrix [Γ] remains. NN Uncertain properties alter the load reflection matrix [Γ] in the scattered field of the antenna mode term. NN The terminal load Z of each element for each load reflection coefficient ln This is achieved by changing the scattered field of the antenna mode terms of the control array, thereby modulating the scattered field of the antenna mode.

[0110] Step 7: Calculate the transmission line length of the impedance matching network based on the optimized non-uniform termination impedance. and parallel single branch length And design an antenna array that includes an impedance matching network.

[0111] 7.1) Based on the impedance transformation principle, the normalized input admittance through the transmission line is... Represented as:

[0112]

[0113] Among them, g′ inFor the input conductance, b′ in For input susceptance, Represents the normalized resistance. Represents normalized reactance;

[0114] 7.2) Based on the optimized normalized termination impedance of each unit According to the principle of single-branch matching, t can be calculated as:

[0115]

[0116] in, Represents the normalized resistance. Represents normalized reactance;

[0117] 7.3) Calculate the electrical length of the transmission line based on t.

[0118]

[0119] 7.4) Based on t and the optimized normalized termination impedance of each unit The input susceptance b′ is calculated using formula 7a). in ;

[0120] 7.5) According to b′ in Calculate the length of a single parallel branch.

[0121]

[0122] 7.6) Based on the electrical length of the transmission line and parallel single-branch electrical length The transmission line length and parallel single stub length of each unit impedance matching network are determined to match the input impedance with the termination impedance, and printed on the back of the 8-element microstrip antenna array to ensure that the scattering field of the structural mode terms is not affected.

[0123] The flowchart representations or method representations of the above embodiments can be understood as representing modules, segments, or portions of code comprising one or more executable instructions configured to implement a specific logical function or process. This invention is not limited to the disclosed preferred embodiments, and its implementation may not follow the order shown or discussed. That is, the step numbers in the specification and claims are only for clear description and understanding of the embodiments of the invention, and their order is not limited.

[0124] Example 2: Customized Control Device for Scattering Surface of Phased Array Antenna Based on Impedance Modulation

[0125] Reference Figure 3This example includes: parameter acquisition module 1, scattered field calculation module 2, function construction module 3, impedance optimization module 4, scattered field modulation module 5, and antenna array design module 6. The scattered field modulation module 5 includes a load reflection matrix submodule 51, an array total scattered field submodule 52, and a scattering cancellation submodule 53. The working principle of the entire system is as follows:

[0126] The parameter acquisition module 1 is used to acquire the S-parameter matrix, the scattering field of the structural mode term and the radiation field in each element array from the N-element linear array antenna to be solved, and transmit the acquired parameters to the function construction module 2.

[0127] The scattering field calculation module 2 is used to establish the analytical relationship between the array radiation field, the antenna mode scattering field, the structure mode scattering field and the total scattering field based on the collected parameters, and transmit the calculated scattering field values ​​to the impedance optimization module 3.

[0128] The function construction module 3 is used to establish an objective function based on each scattering field value so that the optimization iteration process eventually converges to a solution that meets the objective, and transmits the constructed objective function to the impedance optimization module 4;

[0129] The impedance optimization module 4 is used to optimize the non-uniform load impedance through a genetic algorithm, so as to effectively reduce the total RCS of the array to the expected value at the target angle or angular domain, and transmit the optimized load impedance to the scattering field modulation module 5 and the antenna array design module 6.

[0130] The scattering field modulation module 5 is used to cancel the scattering field of the antenna mode terms modulated by the load reflection matrix with the scattering field of the structure mode terms, thereby reducing the RCS of the total array scattering field at the target angle or in the angular domain. The load reflection matrix submodule 51 is used to convert the optimized non-uniform terminal impedance into a load reflection coefficient matrix and transmit the matrix to the total array scattering field submodule. The total array scattering field submodule 52 is used to establish the analytical relationship between the scattering field of the antenna mode terms and the scattering field of the structure mode terms and transmit it to the scattering cancellation submodule. The scattering cancellation submodule is used to change the terminal impedance value of each array element to modulate the scattering field of the antenna mode terms, cancel the scattering field of the antenna mode terms with the scattering field of the structure mode terms, and reduce the RCS of the total array scattering field.

[0131] The antenna array design module 6 is used to design the antenna matching network and achieve target scattering reduction effect.

[0132] It should be noted that the above functional modules can be implemented, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, they can be implemented, in whole or in part, as program instruction products. A program instruction product includes one or a set of program instructions. When the program instructions are loaded and executed on a computer, the described process or function is generated, in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The program instructions can be stored in a computer-readable and writable storage medium, or transferred from one computer's readable and writable storage medium to another.

[0133] The direct coupling or communication connections between the modules shown or discussed in this embodiment can be achieved through indirect coupling or communication connections via interfaces, devices, or modules. The various functional modules and sub-modules in this embodiment can dynamically reside within a single processing unit, or each module can exist physically independently, or two or more modules can dynamically reside within a single processing unit. When these dynamic components are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable and writable storage medium. This storage medium can be a memory, disk, or optical disc, etc.

[0134] The technical effects of the present invention will be further illustrated below with reference to simulation experiments:

[0135] 1. Experimental environment:

[0136] Experimental software: Ansys HFSS2021

[0137] Experimental conditions: The array antenna to be solved was modeled and simulated using Ansys HFSS simulation software. A microstrip patch antenna was used as the antenna element of the array antenna. A 1*8 element planar array was established in the Cartesian coordinate system (xyz coordinate system) as the array antenna for acquiring the scattered field. The antenna elements were uniformly arranged, with a y-axis element spacing of 13mm and an operating frequency of 10GHz. Sampling parameters were set, with a spatial elevation angle θ of -90° to 90° and a spatial azimuth angle of... To acquire the scattered and radiated field data of the array antenna within a 90° range.

[0138] Reference array: An array in which each unit is connected to a matched load.

[0139] 2. Experiment Content:

[0140] Experiment 1: Under the above experimental conditions, the incident plane wave angle was set to 0°, and the scattering optimization target was defined as -60dBsm. The impedance of each element was optimized. Array A with the ideal optimized load impedance as the terminal load and array B with the ideal optimized load replaced by the corresponding impedance matching network were set up. The monostatic RCS of the reference array, array A, and array B at an incident angle of 0° were simulated respectively. The results are as follows: Figure 4 As shown. From Figure 4 As can be seen, at an incident angle of 0°, compared with the reference array, the peak value of the total scattered field at a single station of array A and array B is reduced to -60dBsm.

[0141] Experiment 2: Under the above experimental conditions, the incident plane wave angle was set to 0°, and the scattering optimization target was defined as -60dBsm. The impedance of each element was optimized. The impedance matching network array of this invention was set as B, and the gains of the reference array and array B at an incident angle of 0° were simulated respectively. The results are as follows: Figure 5 As shown, from Figure 5 As can be seen, compared with the reference array, the wide-side gain of the array of the present invention is only reduced by 0.32dB, and the wide-angle scan still covers ±60°.

[0142] Experiment 3: Under the above experimental conditions, the incident plane wave angle was set to -22°, and the scattering optimization target was defined as -60dBsm. The impedance of each element was optimized. Array A was set up with the ideal optimized load impedance as the terminal load, and array B was replaced with the corresponding impedance matching network. The monostatic RCS of the reference array, array A, and array B at an incident angle of -22° was simulated respectively. The results are as follows: Figure 6 As shown. From Figure 6 As can be seen, at an incident angle of -22°, compared with the reference array, the total scattered field RCS of array B at a single station decreases from -37.75dBsm to -60dBsm.

[0143] Experiment 4: Under the above experimental conditions, the incident plane wave angle was set to -22°, and the scattering optimization target was defined as -60dBsm. The impedance of each element was optimized. The impedance matching network array of this invention was set as B, and the array gain of the reference array and array B at an incident angle of -22° was simulated respectively. The results are as follows: Figure 7 As shown. From Figure 7 As can be seen, at an incident angle of -22°, the wide-side gain of the array of the present invention is reduced by only 0.21dB compared with the reference array.

[0144] Experiment 5: Under the above experimental conditions, the incident plane wave angle was set to 22°, and the scattering optimization target was defined as -50dBsm. The additional phase and load resistance of each element were optimized. Array A was set up with an ideal optimized phase delay line and load resistance as the termination. The monostatic RCS of the reference array and array A at an incident angle of 22° were simulated respectively. The results are as follows: Figure 8 As shown, from Figure 8 As can be seen, at an incident angle of -22°, compared with the reference array, the total scattered field RCS of array A at a single station decreased from -37.45dBsm to -49.8dBsm.

[0145] Experiment 6: Under the above experimental conditions, the incident plane wave angle was set to 22°, and the scattering optimization target was defined as -50dBsm. The additional phase and load resistance of each element were optimized. The impedance matching network array of this invention was set as B. The monostatic RCS of the reference array and array B at an incident angle of 22° were simulated respectively. The results are as follows: Figure 9 As shown. From Figure 9 As can be seen, at an incident angle of 22°, compared with the reference array, the total scattered field RCS of array B at a single station decreases from -36.01 dBsm to -51.30 dBsm.

[0146] Experiment 7: Under the above experimental conditions, the incident plane wave angle was set to 22°, and the scattering optimization target was defined as -50dBsm. The additional phase and load resistance of each element were optimized. The impedance matching network array B of this invention was then set up, and the gain of array B at an incident angle of 22° was simulated. The results are as follows: Figure 10 As shown, from Figure 10 It can be seen that the gain drops by less than 0.4 dB on the wide side and less than 0.85 dB on the wide-angle scan.

[0147] Experiment 8: Under the experimental conditions described above, the angular deviation step size for the entire angular domain was set to 1°. The optimized additional phase and load resistance required for each element to reduce the RCS across the entire angular domain were calculated. Array A was set up with an ideal optimized phase delay line and load resistance as the terminals. The single-station RCS of the reference array and array A during RCS reduction across the entire angular domain were simulated respectively. The results are as follows: Figure 11 As shown. From Figure 11 It can be seen that, across the entire angular domain, compared to the reference array, the peak RCS of array A drops below -39.34 dBsm, achieving a reduction of 17.63 dB.

[0148] Experiment 9: Under the above experimental conditions, the angular deviation step size for the entire angular domain was set to 1°. The optimized additional phase and load resistance of each element required for RCS reduction across the entire angular domain were calculated. The impedance matching network array B of this invention was set up, and the single-station RCS of the reference array and array B during RCS reduction across the entire angular domain were simulated respectively. The results are as follows: Figure 12 As shown, from Figure 12 As can be seen, across the entire angular domain, the peak RCS of array B is reduced to below -35.55 dBsm compared to the reference array.

[0149] Experiment 10: Under the above experimental conditions, the angular deviation step size for the entire angular domain was set to 1°. The required additional phase and load resistance of each element to reduce RCS across the entire angular domain were calculated. The gain of the impedance matching network array B of this invention was simulated, and the results are as follows: Figure 13 As shown, Figure 13 Gain plots were plotted for the RCS reduction of the impedance matching network array across the entire angular domain. The results show that the gain decreases by less than 0.4 dB on the wide side and less than 0.85 dB on the wide-angle scan.

[0150] The simulation results above show that, while maintaining radiation performance, the array of the present invention can precisely control the total scattering field of the antenna to a specified value at the required angle or in the angular domain, thereby achieving precise control of the scattering characteristics of the phased array antenna.

Claims

1. A method for customizing the scattering surface of a phased array antenna based on impedance modulation, characterized in that, include: (1) Obtain the S-parameter matrix [S] of the N-element linear array antenna to be solved. NN Scattering field of structural mode terms and the radiation field in each unit array θ is the pitch angle in the measurement space rectangular coordinate system, and φ is the azimuth angle in the measurement space rectangular coordinate system; (2) Utilizing the radiation field of each unit in the array Calculate the scattered field of the array antenna mode terms under arbitrary load. (3) Based on the scattering field of the array antenna mode term Scattering field with structural mode term Calculate the total scattered field E of the array s (θ,φ) and the RCS value of the total scattered field of the antenna; (4) Specify the angle or angle domain for reducing scattering, define the target value σ of the total scattering field RCS at the desired angle or angle domain, and construct a fitness function that includes the deviation between the target value and the actual scattering value. (5) Use intelligent optimization algorithms and an elite retention strategy to iteratively optimize the non-uniform terminal impedance of the scattering field of the mode term of the array antenna until the predefined maximum number of iterations is reached. (6) Using the optimized non-uniform terminal impedance value, change the load reflection matrix [Γ] in the antenna mode term scattered field. NN The antenna mode scattering field is modulated to cancel the structure mode scattering field, so that the total scattering field RCS reaches the specified target value σ, thereby achieving precise customization of the total scattering field. (7) Calculate the transmission line length of the impedance matching network based on the optimized non-uniform termination impedance. and parallel single branch length And design an antenna array that includes an impedance matching network.

2. The method according to claim 1, characterized in that, In (2), the radiation field of each unit in the array is utilized. Calculate the scattered field of the array antenna mode terms under arbitrary load. The formula is as follows: in Let Γ be the matrix composed of the radiation fields of each element in the array. NN Let [I] be the load reflection coefficient matrix for each unit. NN Let [S] be the identity matrix. NN To characterize the mutually coupled S-parameter matrices, To match the received vector.

3. The method according to claim 1, characterized in that, The scattering field based on the array antenna mode term in (3) Scattering field with structural mode term Calculate the total scattered field E of the array s (θ,φ) and the total scattered field RCS of the antenna are realized by: 3a) Scattered field of the array antenna mode term Scattering field with structural mode term Vector addition yields the total scattered field of the array. Calculation of the total scattered field E of the array is also performed. s (θ,φ): 3b) Based on the total scattering field E of the array s (θ,φ) Calculate the RCS value σ of the total scattered field of the antenna. s (θ,φ): Where R is the distance between the target and the receiver, and E i (θ,φ) is the electric field of the scattered wave at the target.

4. The method according to claim 1, characterized in that, The fitness function constructed in (4) that includes the deviation between the target value and the actual scattering value is implemented as follows: 4a) Based on the RCS value σ of the total scattered field of the antenna s (θ s ,φ), when the RCS of the total scattered field is at a specified incident angle θ s During scaling down, the fitness function is defined as follows: Where θ s Let σ(dBsm) represent the desired angle of incidence. s The defined value of the total scattered field RCS, where P is the number of sampling angles, and Z is the total scattered field RCS. ln =R n +jX n R is the terminal impedance of the unit. n X represents resistance. n Indicates reactance; 4b) Based on the RCS value σ of the total scattered field of the antenna s (θ s When the RCS of the total scattered field decreases within the specified angular domain a ≤ s ≤ b, the fitness function is defined as follows: In the formula, a and b are the upper and lower boundaries of the sampling angle domain, respectively. When a = 1 and b = N, the desired angle domain covers the entire angle domain. 4c) Given that the antenna mode term of each array element needs to be propagated twice through the back-end transmission line and its phase needs to be controlled by adding a delay line, the total scattered field E of the array is... s (θ,φ)| Zl It can be represented as: In the formula For additional phase, Z l Z is the load resistance, and Z0 is the characteristic impedance of the transmission line. For the scattering field of the structure mode term, The scattered field of the array antenna mode term; 4d) Modulation of additional phase and load resistance Z l To achieve control over the total scattered field E of the antenna s (θ,φ) control, using load resistance and additional phase as optimization variables, when the RCS of the total scattered field is within the specified angular domain θ a ≤θ s ≤θ b When reducing the internal size, the RCS value σ of the total scattered field of the antenna is used. s (θ s The fitness function is defined as follows: In the formula θ a and θ b These are the upper and lower boundaries of the sampling angle domain, θ d Let K be the sampling angle, K be the number of sampling angles in the entire angle domain, and σ be the sampling angle. s (θ s ,φ) is the total RCS of the phased array at the sampling angle, and σ(dBsm) is the defined target value.

5. The method according to claim 1, characterized in that, The implementation of (5) involves iteratively optimizing the non-uniform terminal impedance of the array antenna mode term scattering field using an intelligent optimization algorithm and an elite retention strategy. 5a) Generate initial particles, set the number of particles, randomly initialize the velocity and position of each particle, and generate the i-th particle in the p-th iteration. in It is the terminal load impedance of the nth element of the i-th particle in the P-th iteration. When the particle is initialized, P = 1. 5b) For each particle's load impedance value, calculate its corresponding fitness function value. Based on the calculation results and the termination condition (maximum number of iterations), determine whether to terminate the optimization process. If the termination condition is met, output the current optimal solution directly and execute step 5d). Otherwise, based on the particle's historical best position and the group's best position, adjust the particle's search direction and step size, update the particle, and execute 5c). 5c) For the updated particles, recalculate their corresponding fitness function values, compare the fitness function values ​​before and after the update, and select the particle positions that are closer to the optimization goal as the optimal positions of the population. 5d) When the iteration meets the termination condition, output the optimal non-uniform terminal load impedance corresponding to the optimal position of the population. This parameter is the optimal solution obtained by the optimization algorithm and can be used to guide actual antenna design.

6. The method according to claim 1, characterized in that, The optimized non-uniform termination impedance value Z obtained in (6) ln , change the load reflection matrix [Γ] in the scattered field of the antenna mode term NN The modulation of the antenna mode scattering field, its implementation includes: 6a) When the array is in receiving mode, according to the non-uniform termination impedance value Z ln Define the load reflection coefficient Γ of the nth element. n for: Z ln Z0 is the load impedance of the nth element in the array, and Z0 is the characteristic impedance of the transmission line. 6b) Utilizing the load reflection coefficient Γ of each unit n Composition of the load reflection coefficient matrix: [C] NN =diag[Γ1,Γ2...Γ n ...C N ]; 6c) Once the array antenna configuration is fixed, the radiation field in each element, the S-parameter matrix representing mutual coupling, and the matched receiver vector are all determined. Only the load reflection coefficient matrix [Γ] remains. NN Uncertain properties alter the load reflection matrix [Γ] in the scattered field of the antenna mode term. NN The terminal load Z of each element for each load reflection coefficient ln This is achieved by changing the scattered field of the antenna mode terms of the control array, thereby modulating the scattered field of the antenna mode.

7. The method according to claim 1, characterized in that, In step (7), the transmission line electrical length of the impedance matching network is calculated based on the optimized non-uniform termination impedance. and parallel single-branch electrical length Its implementation includes: 7a) Based on the impedance transformation principle, the normalized input admittance through the transmission line is... Represented as: Among them, g′ in For the input conductance, b′ in For input susceptance, Represents the normalized resistance. Represents normalized reactance; 7b) Normalize the termination impedance of each unit based on the optimized result. According to the principle of single-branch matching, t can be calculated as: in, Represents the normalized resistance. Represents normalized reactance; 7c) Calculate the electrical length of the transmission line based on t 7d) Based on t and the optimized normalized termination impedance of each unit The input susceptance b′ is calculated using formula 7a). in ; 7e) According to b′ in Calculate the length of a single parallel branch.

8. The method according to claim 1, characterized in that, The antenna array design in (7) that includes an impedance matching network is based on the electrical length of the transmission line. and parallel single-branch electrical length Determine the transmission line length and parallel single stub length of each unit impedance matching network to match the input impedance with the termination impedance, and print it on the back of the antenna array to ensure that the scattering field of the structural mode terms is not affected.

9. A custom control device for the scattering surface of a phased array antenna based on impedance modulation, characterized in that, include: The parameter acquisition module is used to acquire the S-parameter matrix, the scattering field of the structural mode term, and the radiation field in each element of the N-element linear array antenna to be solved. The scattered field calculation module is used to establish the analytical relationship between the array radiation field, the antenna mode scattered field, the structure mode scattered field, and the total scattered field. The function building module is used to create the objective function so that the optimization iteration process eventually converges to a solution that meets the objective. The impedance optimization module is used to optimize the non-uniform load impedance through a genetic algorithm, so as to effectively reduce the total field RCS of the array to the expected value at the target angle or angular domain. The scattering field modulation module is used to cancel the scattering field of the antenna mode terms modulated by the load reflection matrix with the scattering field of the structure mode terms, thereby reducing the RCS of the total array scattering field at the target angle or in the angular domain. The antenna array design module is used to design antenna matching networks and achieve target scattering reduction.

10. The apparatus according to claim 9, characterized in that, The scattering field modulation module includes: The load reflection matrix submodule is used to convert the optimized non-uniform termination impedance into a load reflection coefficient matrix. The array total scattering field submodule is used to establish the analytical relationship between the antenna mode scattering field and the structure mode term scattering field; The scattering cancellation submodule is used to change the terminal impedance value of each array element to modulate the scattering field of the antenna mode terms, cancel the scattering field of the antenna mode terms with the scattering field of the structural mode terms, and reduce the total scattering field RCS of the array.

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