Signal orientation estimation method based on multi-channel vector digital beam forming and amplitude comparison

Abstract

The invention discloses a signal orientation estimation method based on multi-channel vector digital beam forming and amplitude comparison, and belongs to the technical field of digital signal processing. The problem that a traditional digital beam forming algorithm cannot be applied to conformal antenna array direction finding is solved. The method specifically comprises the following steps: step 1, arranging a conformal antenna array model composed of conformal antenna array elements; step 2, vector digital beam forming is carried out on the received polarization signals of the conformal antenna array model to form a plurality of beams with different directions; step 3, searching different directional beams formed in the step 2, and searching a polarization parameter and an incident direction corresponding to the maximum beam; and 4, selecting three wave beams according to the polarization parameters and the incident direction searched in the step 3, and comparing the amplitude by using the selected three wave beams to obtain a final incident angle estimation result of the incident electromagnetic wave signal. The method can be applied to signal orientation estimation.

Description

Technical Field

[0001] The invention belongs to the technical field of digital signal processing, and in particular relates to a signal azimuth estimation method based on multi-channel vector digital beamforming and amplitude comparison. Background Art

[0002] In an increasingly complex electromagnetic environment, in response to the application requirements of passive radar seekers, such as widening the frequency coverage range, high sensitivity and anti-interference capabilities, radar seekers mostly use dual-mode or multi-mode composite guidance. However, due to the problem of multiple guidance modes competing for aperture resources in composite guidance, the placement of passive direction finding antennas is limited, which requires the passive radar direction finding system to try to find a more flexible placement method to provide space for other guidance modes. To solve this problem, conformal antennas are often used in passive radar guidance. Conformal antennas can work in an ultra-wide frequency band and fit perfectly with the shape of the carrier, meeting the needs of passive radar seekers in anti-radiation missiles.

[0003] Although the traditional digital beamforming (DBF) algorithm has the advantages of improving system sensitivity, increasing the effective range, enhancing useful signals, improving the zero point control of the main beam and sidelobe patterns, and simultaneously forming multiple low sidelobes to suppress interference and noise, and automatically calibrating the mutual coupling of single elements, the conformal antenna is sensitive to polarization information. In addition to receiving angle information, it also receives polarization information, and the conformal antenna receiving polarization information will cause additional phase difference. Therefore, the traditional digital beamforming algorithm is no longer suitable for the direction finding of conformal antenna arrays. In summary, it is an urgent problem to propose a passive direction finding algorithm suitable for conformal antennas. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the traditional digital beamforming algorithm cannot be applied to conformal antenna array direction finding, and propose a signal direction estimation method based on multi-channel vector digital beamforming and amplitude comparison.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a signal azimuth estimation method based on multi-channel vector digital beamforming and amplitude comparison, the method specifically comprising the following steps:

[0006] Step 1: Arrange a conformal antenna array model composed of conformal antenna array elements, and construct a receiving polarization signal model of the conformal antenna array model;

[0007] Step 2: performing vector digital beamforming on the received polarized signal of the conformal antenna array model to form multiple beams with different directions;

[0008] Step 3: Search the different directional beams formed in step 2 to find out the polarization parameter and incident direction corresponding to the maximum beam;

[0009] Step 4: Select three beams according to the polarization parameters and incident directions searched out in step 3, and use the selected three beams to compare amplitudes to obtain a final incident angle estimation result of the incident electromagnetic wave signal.

[0010] Furthermore, in step 1, an antenna array model composed of conformal antenna elements is arranged, specifically:

[0011] In the xoy plane of the global rectangular coordinate system, a uniform circular array composed of M conformal antenna elements is arranged, and each element is tangent to the circumferential surface of the circular array. The positive direction of the conformal antenna is defined as the right side of the opening protrusion of the conformal antenna, and the pointing angle α of the conformal antenna is defined as the angle between the positive direction of the conformal antenna and the positive semi-axis of the x-axis.

[0012] Furthermore, in step 1, the received polarization signal model is:

[0013] Step 1: Assume that the incident direction vector of the far-field electromagnetic wave signal is The azimuth angle of the incident direction vector is θ, the elevation angle is φ, and the plane where the electric field vector E of the incident electromagnetic wave signal lies is parallel to the incident direction vector Vertically, the horizontal direction of the plane where the electric field vector E is located is recorded as The vertical direction of the plane where the electric field vector E lies is recorded as The electric field vector E is in the horizontal direction The component is e h , the electric field vector E is in the vertical direction The component is e v , then the electric field vector E is expressed as:

[0014]

[0015] The polarization auxiliary angle γ is the horizontal amplitude component e of the electric field vector E h and the vertical amplitude component e v The polarization phase difference η is the difference in the initial phase. The polarization auxiliary angle γ and the polarization phase difference η are used to obtain the representation of the electric field vector E in the global rectangular coordinate system:

[0016]

[0017] Where, e is the base of the natural logarithm, j is the imaginary unit, and Z is the elliptical size of the electric field vector polarization ellipse;

[0018] Step 1 and 2: According to the representation of the electric field vector E in the global rectangular coordinate system, the polarization-angle steering vector a of the incident electromagnetic wave signal is obtained.p (θ,φ,γ,η):

[0019]

[0020] Then the received polarization signal model of the conformal antenna array model is:

[0021]

[0022] Where X(t) represents the polarization signal received by the conformal antenna array at time t, S(t) represents the target signal at time t, and n(t) represents the noise signal at time t. Represents the spatial steering vector.

[0023] Furthermore, the calculation method of the ellipse size Z of the electric field vector polarization ellipse is:

[0024] Taking the major axis and minor axis of the electric field vector polarization ellipse as the two right-angled sides of a right triangle, the ellipse size Z is the length of the hypotenuse of the right triangle.

[0025] Furthermore, the specific process of step 2 is as follows:

[0026] The complex weight vector of each conformal antenna array element is denoted as w = [w1, w2, ..., w M ],w1,w2,…,w M Denote the complex weighting coefficients of the first, second, ..., Mth conformal antenna array elements respectively. The signal X(t) is weighted by the complex weighting vector to obtain the beam y(t):

[0027] y(t)=w H X(t)

[0028] Among them, w H represents the conjugate transpose of the complex weight vector w.

[0029] Furthermore, the complex weight vector w is specifically:

[0030]

[0031] in, Indicates the direction The spatial phase factor of the incident electromagnetic wave signal located at the first array element, Indicates the direction The spatial phase factor of the incident electromagnetic wave signal located at the Mth array element, B = [b1 T ,b2 T ,…,b M T ],m=1,2,…,M,b m =[sin(dxm / r)cos(d ym / r)], r is the array radius, d xm and d ym are the coordinate positions of the center projection of the m-th array element on the x-axis and y-axis respectively, Θ and Φ are the sets of azimuth angle and elevation angle, respectively; Υ and Ξ are the sets of polarization auxiliary angle and polarization phase difference, respectively; Indicates azimuth Pitch Angle Polarization auxiliary angle Polarization phase difference The corresponding polarization-angle steering vector;

[0032]

[0033] Wherein, m=1,2,…,M, and λ is the wavelength of the incident electromagnetic wave signal.

[0034] Furthermore, the specific process of step three is:

[0035] Establish the objective function:

[0036]

[0037] Solving the objective function, we get the estimated value of the incident azimuth and the pitch angle estimate That is, the incident direction corresponding to the maximum beam, the estimated value of the polarization auxiliary angle and the polarization phase difference estimate That is the polarization parameter corresponding to the maximum beam.

[0038] Furthermore, the specific process of step 4 is as follows:

[0039] The azimuth angle corresponding to the maximum beam searched in step 3 is recorded as θ i , the pitch angle corresponding to the maximum beam searched in step 3 is recorded as Then the azimuth angle is selected as θ i-1 And the pitch angle is The beam and azimuth angle are θ i+1 And the pitch angle is The beam;

[0040] Will The corresponding beam amplitude is recorded as Will The corresponding beam amplitude is recorded as Will The corresponding beam amplitude is recorded as The final incident azimuth is and the final incident pitch angle They are:

[0041]

[0042] Among them, θ 0.5 is the beamwidth in the azimuth dimension, is the beamwidth in the elevation dimension.

[0043] The beneficial effects of the present invention are:

[0044] Aiming at the problem that the passive radar direction finding system in the radar seeker needs to adapt to both the ultra-wide frequency band and the conformal antenna that is sensitive to polarization information, and at the same time provide space resources for the direction finding systems of other modes, the present invention proposes a multi-channel vector digital beamforming-amplitude comparison algorithm. The method of the present invention utilizes the vector digital beamforming technology to form a beam with a specified direction and polarization parameters, and then performs direction finding on the received signal of the conformal antenna array. Furthermore, on the basis of the vector digital beamforming, a multi-beam amplitude comparison method is adopted to improve the direction finding accuracy.

[0045] The algorithm of the present invention takes into account the influence of the spatial polarization characteristics of the receiving antenna and can adapt to the ultra-wide frequency band of 0.8 GHz-18 GHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of a uniform circular array of the present invention;

[0047] Figure 2 A schematic diagram of a receiving antenna direction finding space rectangular coordinate system in the present invention;

[0048] Figure 3 The azimuth angles in the present invention are θ i-1 ,θ i and θ i+1 Schematic diagram of the three beam patterns;

[0049] FIG4( a ) is a 0.8 GHz beam pattern formed using the vector digital beamforming technology of the present invention;

[0050] FIG4( b ) is a 18 GHz beam pattern formed using the vector digital beamforming technology of the present invention;

[0051] Figure 5 It is the angle measurement error of the VDBF algorithm (vector digital beamforming technology) and the VDBF-AC algorithm (vector digital beamforming technology-amplitude comparison) in the present invention under different signal-to-noise ratios;

[0052] Figure 6 It is the angle measurement error of the present invention at the frequency of 0.8 GHz-18 GHz. DETAILED DESCRIPTION

[0053] Specific implementation method 1: This implementation method is a signal direction estimation method based on multi-channel vector digital beamforming and amplitude comparison, and the method specifically includes the following steps:

[0054] Step 1: Arrange a conformal antenna array model composed of conformal antenna array elements, and construct a receiving polarization signal model of the conformal antenna array model;

[0055] Step 2: performing vector digital beamforming (phase shifting) on ​​the received polarized signal of the conformal antenna array model to form multiple beams with different directions;

[0056] Step 3: Search the different directional beams formed in step 2 to find out the polarization parameters and incident direction corresponding to the maximum beam (i.e., obtain the parameter combination corresponding to the maximum beam by traversing and searching each group of parameter combinations);

[0057] Step 4: Select three beams according to the polarization parameters and incident directions searched out in step 3, and use the selected three beams to compare amplitudes to obtain a final incident angle estimation result of the incident electromagnetic wave signal.

[0058] The present invention assumes that the receiving array receives the main beam of the transmitting antenna, and the measurement result is the main polarization of the transmitting antenna. At the same time, the coordinate system of the receiving array is the same as the global coordinate system.

[0059] Specific implementation method 2: Combination Figure 1 This embodiment is different from the first embodiment in that, in step 1, an antenna array model composed of conformal antenna elements is arranged, specifically:

[0060] In the xoy plane of the global rectangular coordinate system, a uniform circular array consisting of M conformal antenna elements is arranged (the value of M in the present invention is 8), and each element is tangent to the circumferential surface of the circular array. The positive direction of the conformal antenna is defined as the right side of the opening protrusion of the conformal antenna, and the pointing angle α of the conformal antenna is defined as the angle between the positive direction of the conformal antenna and the positive semi-axis of the x-axis.

[0061] The other steps and parameters are the same as those in the first embodiment.

[0062] The uniform circular array in the present invention means that the distances between any two adjacent array elements are equal.

[0063] Specific implementation method three: Combination Figure 2 This embodiment is different from the specific embodiment 1 or 2 in that, in step 1, the received polarization signal model is:

[0064] Step 1: Assume that the incident direction vector of the far-field electromagnetic wave signal is The azimuth angle of the incident direction vector is θ, the elevation angle is φ, and the plane where the electric field vector E of the incident electromagnetic wave signal lies is parallel to the incident direction vector Vertically, the horizontal direction of the plane where the electric field vector E is located is recorded as The vertical direction of the plane where the electric field vector E lies is recorded as The electric field vector E is in the horizontal direction The component is e h , the electric field vector E is in the vertical direction The component is e v , then the electric field vector E is expressed as:

[0065]

[0066] The polarization auxiliary angle γ is the horizontal amplitude component e of the electric field vector E h and the vertical amplitude component e v The ratio of the polarization phase difference η is the difference in the initial phase, where γ∈[0,π / 2], η∈[-π,π]; According to the polarization characteristics of the incident electromagnetic wave signal, the polarization auxiliary angle γ and the polarization phase difference η are used to obtain the representation of the electric field vector E in the global rectangular coordinate system:

[0067]

[0068] Where, e is the base of the natural logarithm, j is the imaginary unit, and Z is the elliptical size of the electric field vector polarization ellipse;

[0069] Step 1 and 2: According to the representation of the electric field vector E in the global rectangular coordinate system, the polarization-angle steering vector a of the incident electromagnetic wave signal is obtained. p (θ,φ,γ,η):

[0070]

[0071] Then the received polarization signal model of the conformal antenna array model is:

[0072]

[0073] Where X(t) represents the polarization signal received by the conformal antenna array at time t, S(t) represents the target signal at time t, and n(t) represents the noise signal at time t. Represents the spatial steering vector.

[0074] The other steps and parameters are the same as those in the first or second embodiment.

[0075] Specific implementation method 4: This implementation method is different from any one of specific implementation methods 1 to 3 in that the calculation method of the ellipse size Z of the electric field vector polarization ellipse is:

[0076] Taking the major axis and minor axis of the electric field vector polarization ellipse as the two right-angled sides of a right triangle, the ellipse size Z is the length of the hypotenuse of the right triangle.

[0077] The other steps and parameters are the same as those in Specific Embodiments 1 to 3.

[0078] Z 2 It represents the power of the incident electromagnetic wave signal.

[0079] Specific implementation method 5: This implementation method is different from the specific implementation methods 1 to 4 in that the specific process of step 2 is as follows:

[0080] The complex weight vector of each conformal antenna array element is denoted as w = [w1, w2, ..., w M ],w1,w2,…,w M They represent the complex weighting coefficients of the first, second, …, Mth conformal antenna array elements respectively. The signal X(t) is weighted by the complex weighting vector to obtain the beam y(t). That is, according to the principle of vector digital beamforming, the signal X(t) received by the array element is phase-shifted to obtain the signal matrix after phase shifting:

[0081] y(t)=w H X(t)

[0082] Among them, w H It represents the conjugate transpose of the complex weight vector w. By changing the complex weight coefficient in the complex weight vector w, beams with different directions can be obtained.

[0083] The other steps and parameters are the same as those in Specific Embodiments 1 to 4.

[0084] Vector digital beamforming selects appropriate complex weight vectors to compensate for the phase difference of signals received by different array elements and the additional phase difference caused by the polarization characteristics of the antenna, so that they are added in phase in a specific direction and polarization characteristics to form a beam with a specified direction and polarization characteristics. When the phase shift angle is the same as the direction of the incident signal, and the phase shift polarization tilt angle and polarization ellipse angle are consistent with the actual signal polarization parameters, the amplitude obtained by the phase shift superposition of the signals received by M array elements reaches the maximum, so the approximate range of the azimuth, elevation angle and polarization parameters of the incident signal can be estimated by searching.

[0085] Specific implementation method 6: This implementation method is different from any one of the specific implementation methods 1 to 5 in that the complex weight vector w is specifically:

[0086]

[0087] in, Indicates the direction The spatial phase factor of the incident electromagnetic wave signal located at the first array element, Indicates the direction The spatial phase factor of the incident electromagnetic wave signal located at the Mth array element, B = [b1 T ,b2 T ,…,b M T ],m=1,2,…,M,b m =[sin(d xm / r)cos(d ym / r)], r is the array radius, d xm and d ym are the coordinate positions of the center projection of the m-th array element on the x-axis and y-axis respectively, Θ and Φ are the sets of azimuth angle and elevation angle, respectively; Υ and Ξ are the sets of polarization auxiliary angle and polarization phase difference, respectively; Indicates azimuth Pitch Angle Polarization auxiliary angle Polarization phase difference The corresponding polarization-angle steering vector;

[0088]

[0089] Wherein, m=1,2,…,M, and λ is the wavelength of the incident electromagnetic wave signal.

[0090] The other steps and parameters are the same as those in Specific Implementation Methods 1 to 5.

[0091]

[0092] Considering that the signal incident spatial domain is limited and the range of polarization parameter variation is also limited, the exhaustive method can be used to obtain the complete angle set Θ and Φ, which is obtained from the possible incident azimuth angles. and pitch angle Similarly, the sets of polarization auxiliary angles and polarization phase differences Υ and Ξ can be obtained,

[0093] All possible parameter combinations of the present invention are described below:

[0094] The polarization auxiliary angle values ​​are uniformly selected within the range of polarization auxiliary angle variation, and the polarization auxiliary angle values ​​are respectively recorded as γ1, γ2, …, γ A′ ,γ1,γ2,…,γ A′ The polarization auxiliary angle variation range is divided into A′-1 intervals with equal intervals. Each polarization phase difference is uniformly selected within the polarization phase difference variation range, and each polarization phase difference value is recorded as η1, η2, …, ηB′ ,η1,η2,…,η B′ The polarization phase difference variation range is divided into B′-1 intervals with equal intervals. Each azimuth angle is uniformly selected within the azimuth variation range, and each azimuth angle value is recorded as θ1, θ2, …, θ C ,θ1,θ2,…,θ C The azimuth angle variation range is divided into C-1 intervals with equal intervals. Each pitch angle is evenly selected within the pitch angle variation range, and each pitch angle value is recorded as Divide the pitch angle variation range into D-1 intervals with equal intervals; then

[0095] Let γ1, η1, θ1 and As a parameter combination, γ1, η1, θ1 and As a parameter combination, ..., γ1, η1, θ1 and As a parameter combination;

[0096] Let γ1, η1, θ2 and As a parameter combination, γ1, η1, θ2 and As a parameter combination, ..., γ1, η1, θ2 and As a parameter combination;

[0097] …

[0098] Let γ1, η1, θ C and As a parameter combination, γ1, η1, θ C and As a parameter combination, ..., γ1, η1, θ C and As a parameter combination;

[0099] Let γ1, η2, θ1 and As a parameter combination, γ1, η2, θ1 and As a parameter combination, ..., γ1, η2, θ1 and As a parameter combination;

[0100] Let γ1, η2, θ2 and As a parameter combination, γ1, η2, θ2 and As a parameter combination, ..., γ1, η2, θ2 and As a parameter combination;

[0101] …

[0102] Let γ1, η2, θ C and As a parameter combination, γ1, η2, θ C and As a parameter combination, ..., γ1, η2, θ C and As a parameter combination;

[0103] …

[0104] Set γ1, η B′ , θ1 and As a parameter combination, γ1, η B′ , θ1 and As a parameter combination, ..., γ1, η B′ , θ1 and As a parameter combination;

[0105] Set γ1, η B′ , θ2 and As a parameter combination, γ1, η B′ , θ2 and As a parameter combination, ..., γ1, η B′ , θ2 and As a parameter combination;

[0106] …

[0107] Set γ1, η B′ ,θ C and As a parameter combination, γ1, η B′ ,θ C and As a parameter combination, ..., γ1, η B′ ,θ C and As a parameter combination;

[0108] By analogy, all possible combinations are traversed for each polarization auxiliary angle value. According to each group of parameter combinations, vector digital beamforming is performed to obtain a directional beam.

[0109] Specific implementation method 7: This implementation method is different from the specific implementation methods 1 to 6 in that the specific process of step 3 is as follows:

[0110] Establish the objective function:

[0111]

[0112] Solving the objective function, we get the estimated value of the incident azimuth and the pitch angle estimate That is, the incident direction corresponding to the maximum beam, the estimated value of the polarization auxiliary angle and the polarization phase difference estimate That is the polarization parameter corresponding to the maximum beam.

[0113] The other steps and parameters are the same as those in Specific Embodiments 1 to 6.

[0114] Specific implementation method eight: Combination Figure 3 This embodiment is different from the first to seventh embodiments in that the specific process of step 4 is as follows:

[0115] The azimuth angle corresponding to the maximum beam searched in step 3 is recorded as θ i , the pitch angle corresponding to the maximum beam searched in step 3 is recorded as Then the azimuth angle is selected as θ i-1 And the pitch angle is The beam and azimuth angle are θ i+1 And the pitch angle is It should be noted that the selected beam is also estimated from the polarization auxiliary angle. and the polarization phase difference estimate The corresponding beam is selected;

[0116] Among them, θ i-1 ,θ i and θ i+1 They are the i-1th, i-th and i+1th azimuths in the azimuth set respectively; and They are the i-1th, i-th and i+1th pitch angles in the pitch angle set respectively;

[0117] definition and are the beam diagram functions corresponding to the first, second and third beams selected respectively. The corresponding beam amplitude is recorded as Will The corresponding beam amplitude is recorded as Will The corresponding beam amplitude is recorded as By comparing the amplitudes to determine the specific direction of the signal, the final incident azimuth and the final incident pitch angle They are:

[0118]

[0119] Among them, θ 0.5 is the beamwidth in the azimuth dimension, is the beamwidth in the elevation dimension.

[0120] The other steps and parameters are the same as those in Specific Embodiments 1 to 7.

[0121] Experimental Section

[0122] In order to verify the beneficial effects of the present invention, a simulation experiment is conducted as follows: a uniform circular array is formed by 8 electric dipole antennas, and the radius r of the circular array is 300 mm. It is assumed that the relative angle between the electromagnetic wave of the transmitting antenna and the receiving array is 0° in azimuth and 0° in elevation. In addition, the polarization of the transmitting antenna is vertical polarization (relative to the ground).

[0123] 4(a) and 4(b) respectively show the beam patterns formed by the present invention using vector digital beamforming technology with an azimuth angle of 0°, an elevation angle of 0°, a vertical polarization, and a frequency of 0.8 GHz and 18 GHz.

[0124] Figure 5 The following is a graph showing the RMSE of the angle information estimated by the algorithm of the present invention and the vector digital beamforming technology without amplitude comparison direction finding at a frequency of 6 GHz. Assume that the angle between the transmitting signal and the receiving array is (14.3°, 3.8°), the polarization parameters (γ, η) of the transmitting antenna are (10°, 0°), and the number of experiments is 100.

[0125] Figure 6 The following is a graph showing the RMSE of the angle information estimated by the algorithm of the present invention as a function of the signal-to-noise ratio at frequencies between 0.8 GHz and 18 GHz. Assume that the angle between the transmitted signal and the receiving array is (14.3°, 3.8°), the polarization parameters (γ, η) of the transmitting antenna are (10°, 0°), and the number of experiments is 100.

[0126] Depend on Figure 5 and Figure 6 It can be seen that the algorithm of the present invention has good direction finding performance in the wide frequency band of 0.8 GHz-18 GHz and can adapt to the polarization characteristics of the conformal antenna.

[0127] In summary, the present invention discloses an eight-channel vector digital beamforming-amplitude comparison algorithm. Based on the digital beamforming technology, the method of the present invention proposes a vector digital beamforming technology to adapt to the polarization-sensitive characteristics of the conformal antenna, form a beam with a specified direction and polarization parameters, and then perform direction finding on the antenna received signal, and can adapt to the ultra-wide frequency band of 0.8GHz-18GHz. On the basis of vector digital beamforming, the multi-beam amplitude comparison method is used to improve the direction finding accuracy. The method of the present invention takes into account the influence of the spatial polarization characteristics of the receiving antenna and the ultra-wide frequency adaptation range, and improves the algorithm direction finding accuracy.

[0128] The above calculation examples of the present invention are only used to explain the calculation model and calculation process of the present invention in detail, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A signal direction estimation method based on multi-channel vector digital beamforming and amplitude comparison, characterized in that: The method specifically comprises the following steps: Step 1: Arrange a conformal antenna array model composed of conformal antenna array elements, and construct a receiving polarization signal model of the conformal antenna array model; Step 2: performing vector digital beamforming on the received polarized signal of the conformal antenna array model to form multiple beams with different directions; Step 3: Search the different directional beams formed in step 2 to find out the polarization parameter and incident direction corresponding to the maximum beam; Step 4: Select three beams according to the polarization parameters and incident directions searched out in step 3, and use the selected three beams to compare amplitudes to obtain a final incident angle estimation result of the incident electromagnetic wave signal.

2. The signal direction estimation method based on multi-channel vector digital beamforming and amplitude comparison according to claim 1, characterized in that: In step 1, an antenna array model consisting of conformal antenna elements is arranged, specifically: In the xoy plane of the global rectangular coordinate system, a uniform circular array composed of M conformal antenna elements is arranged, and each element is tangent to the circumferential surface of the circular array. The positive direction of the conformal antenna is defined as the right side of the opening protrusion of the conformal antenna, and the pointing angle α of the conformal antenna is defined as the angle between the positive direction of the conformal antenna and the positive semi-axis of the x-axis.

3. The signal direction estimation method based on multi-channel vector digital beamforming and amplitude ratio according to claim 2, characterized in that: In the step 1, the received polarization signal model is: Step 1: Assume that the incident direction vector of the far-field electromagnetic wave signal is The azimuth angle of the incident direction vector is θ, the elevation angle is φ, and the plane where the electric field vector E of the incident electromagnetic wave signal lies is parallel to the incident direction vector Vertically, the horizontal direction of the plane where the electric field vector E is located is recorded as The vertical direction of the plane where the electric field vector E lies is recorded as The electric field vector E is in the horizontal direction The component is e h , the electric field vector E is in the vertical direction The component is e v , then the electric field vector E is expressed as: The polarization auxiliary angle γ is the horizontal amplitude component e of the electric field vector E h and the vertical amplitude component e v The polarization phase difference η is the difference in the initial phase. The polarization auxiliary angle γ and the polarization phase difference η are used to obtain the representation of the electric field vector E in the global rectangular coordinate system: Where, e is the base of the natural logarithm, j is the imaginary unit, and Z is the elliptical size of the electric field vector polarization ellipse; Step 1 and 2: According to the representation of the electric field vector E in the global rectangular coordinate system, the polarization-angle steering vector a of the incident electromagnetic wave signal is obtained. p (θ,φ,γ,η): Then the received polarization signal model of the conformal antenna array model is: Where X(t) represents the polarization signal received by the conformal antenna array at time t, S(t) represents the target signal at time t, and n(t) represents the noise signal at time t. Represents the spatial steering vector.

4. The signal direction estimation method based on multi-channel vector digital beamforming and amplitude comparison according to claim 3 is characterized in that: The calculation method of the ellipse size Z of the electric field vector polarization ellipse is: Taking the major axis and minor axis of the electric field vector polarization ellipse as the two right-angled sides of a right triangle, the ellipse size Z is the length of the hypotenuse of the right triangle.

5. The signal direction estimation method based on multi-channel vector digital beamforming and amplitude ratio according to claim 4, characterized in that: The specific process of step 2 is as follows: The complex weight vector of each conformal antenna array element is denoted as w = [w1, w2, ..., w M ],w1,w2,...,w M Denote the complex weighting coefficients of the first, second, ..., Mth conformal antenna array elements respectively. The signal X(t) is weighted by the complex weighting vector to obtain the beam y(t): y(t)=w H X(t) Among them, w H represents the conjugate transpose of the complex weight vector w.

6. The signal direction estimation method based on multi-channel vector digital beamforming and amplitude comparison according to claim 5, characterized in that: The complex weight vector w is specifically: in, Indicates the direction The spatial phase factor of the incident electromagnetic wave signal located at the first array element, Indicates the direction The spatial phase factor of the incident electromagnetic wave signal located at the Mth array element, B = [b1 T ,b2 T ,...,b M T ],m=1,2,…,M,b m =[sin(d xm / r)cos(d ym / r)], r is the array radius, d xm and d ym are the coordinate positions of the center projection of the m-th array element on the x-axis and y-axis respectively, Θ and Φ are the sets of azimuth angle and elevation angle, respectively; Υ and Ξ are the sets of polarization auxiliary angle and polarization phase difference, respectively; Indicates azimuth Pitch Angle Polarization auxiliary angle Polarization phase difference The corresponding polarization-angle steering vector; Wherein, m=1,2,…,M, and λ is the wavelength of the incident electromagnetic wave signal.

7. The signal direction estimation method based on multi-channel vector digital beamforming and amplitude comparison according to claim 6, characterized in that: The specific process of step three is: Establish the objective function: Solving the objective function, we get the estimated value of the incident azimuth and the pitch angle estimate That is, the incident direction corresponding to the maximum beam, the estimated value of the polarization auxiliary angle and the polarization phase difference estimate That is the polarization parameter corresponding to the maximum beam.

8. The signal direction estimation method based on multi-channel vector digital beamforming and amplitude comparison according to claim 7, characterized in that: The specific process of step 4 is as follows: The azimuth angle corresponding to the maximum beam searched in step 3 is recorded as θ i , the pitch angle corresponding to the maximum beam searched in step 3 is recorded as Then the azimuth angle is selected as θ i-1 And the pitch angle is The beam and azimuth angle are θ i+1 And the pitch angle is The beam; Will The corresponding beam amplitude is recorded as Will The corresponding beam amplitude is recorded as Will The corresponding beam amplitude is recorded as The final incident azimuth is and the final incident pitch angle They are: Among them, θ 0.5 is the beamwidth in the azimuth dimension, is the beamwidth in the elevation dimension.

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