Monopole / crossed loop antenna pattern measurement and direction finding error estimation method and system

Abstract

The application discloses a monopole / crossed loop antenna pattern measurement and direction finding error estimation method and system, first, the real distortion pattern is estimated by using the multiple measured patterns of the monopole / crossed loop antenna, the measurement error of the antenna pattern is calculated, then the direction finding error is estimated according to the multiple signal classification algorithm based on the measured antenna pattern and the measurement error. Compared with the existing monopole / crossed loop direction finding error estimation method, the application distinguishes the measured pattern from the real distortion pattern, gives the calculation method of the real distortion pattern and the pattern measurement error, quantifies the influence degree of the pattern measurement error on the azimuth angle estimation, and makes up for the research vacancy of the influence of the pattern measurement error on the antenna direction finding.

Description

Technical Field

[0001] This invention belongs to the field of high-frequency radar azimuth estimation technology, specifically relating to a method and system for measuring the radiation pattern and estimating the direction finding error of a monopole / cross-loop antenna. Background Technology

[0002] High-frequency ground wave radar (HFG) utilizes the characteristic of low attenuation during diffraction propagation of vertically polarized electromagnetic waves over the sea surface, enabling large-scale, all-weather, over-the-horizon, real-time continuous observation of ocean surface dynamic parameters. It is widely used in marine remote sensing and sea surface target detection. Early HFG radars were mostly phased array type, with narrow beams and high azimuth resolution, but they required a large footprint and high maintenance costs. To address these shortcomings, compact HFG radars employ monopole / cross-loop receiving antennas, which have a smaller footprint, lower installation requirements, and are easier to maintain. Furthermore, they achieve higher azimuth measurement accuracy through a multiple signal classification algorithm (MUSIC), making them more popular in the industry. Currently, compact HFG radar systems, such as the SeaSonde system from Codar Corporation in the United States and the OSMAR-S system from Wuhan University, are widely used worldwide.

[0003] In practical applications, the inconsistency of the radar system's own channels and the radiation pattern distortion caused by the surrounding environment can seriously affect the accuracy of azimuth estimation. Currently, the most effective way to solve this problem is to measure the antenna's true distorted radiation pattern to obtain its amplitude and phase responses in different azimuths, and then use this measured radiation pattern to estimate the signal azimuth. Inspired by the above solution, traditional methods use vehicle-mounted, ship-mounted, or manually loaded transponders to move around the antenna to achieve radiation pattern measurement. However, to address the limitation of the transponder's movement trajectory being restricted by the antenna installation environment, Chinese patent CN202010456794.8, entitled "A Linear Frequency Modulation Radar Antenna Radar ...

[0004] As can be seen from the above analysis, in the process of measuring antenna radiation patterns, measurement errors are unavoidable due to the limitations of measurement methods. Most existing studies treat the measured radiation pattern as the true distorted radiation pattern and ignore the impact of measurement errors on the orientation estimation. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and system for measuring the radiation pattern and estimating the direction-finding error of a monopole / cross-loop antenna. The method estimates the true distorted radiation pattern using multiple radiation pattern measurements of the monopole / cross-loop antenna, calculates the measurement error of the radiation pattern, and estimates the direction-finding error based on the measured antenna radiation pattern and its measurement error using a multiple signal classification algorithm.

[0006] To achieve the above objectives, the present invention provides a method for measuring the radiation pattern and estimating the direction finding error of a monopole / cross-loop antenna, comprising the following steps:

[0007] Step 1: Obtain multiple measurement results of the radar antenna pattern in the actual environment, and calculate the average value of the multiple measured results as the true distorted antenna pattern.

[0008] Step 2: Calculate the difference between the measured antenna pattern and the actual distorted antenna pattern of the two-loop channel in a certain measurement to obtain the measurement error of the antenna pattern of the two-loop channel in a certain measurement.

[0009] Step 3: Generate radar received echo signals based on the actual distorted radiation pattern. Using a measured radiation pattern, estimate the azimuth angle of the received echo signals in any direction using a multi-signal classification algorithm.

[0010] Step 4: Calculate the difference between the azimuth angle estimation result of any azimuth echo signal described in Step 3 and the true azimuth angle to obtain the magnitude of the azimuth angle estimation error.

[0011] Furthermore, the multiple measurement results of the monopole / cross-loop antenna pattern in the actual environment in step 1 are defined as follows:

[0012] a di (θ)=[1,g 2i (θ)cos(θ+π / 4),g 3i (θ)sin(θ+π / 4)], i=1,2,3,...,N(1)

[0013] In the formula, a di (θ) represents the measured antenna pattern obtained from the i-th measurement, where θ is the azimuth angle, and g 2i (θ) is the distortion factor of the cosine ring in the i-th measurement, i.e., the amplitude and phase difference of the cosine ring channel relative to the first antenna channel, g 3i (θ) is the distortion factor of the sin ring in the i-th measurement, that is, the amplitude and phase difference of the sin ring channel relative to the first antenna channel, π is pi, and N is the total number of antenna pattern measurements.

[0014] The true distortion pattern of a monopole / cross-loop antenna is calculated using the following formula:

[0015]

[0016] In the formula, a r (θ) represents the true distorted antenna pattern, a di (θ) represents the measured antenna pattern obtained from the i-th measurement, where θ is the azimuth angle and N is the total number of antenna pattern measurements.

[0017] Furthermore, in step 2, the true distortion pattern of the two-ring channel, as defined in step 1, is a. rB (θ) and a rA (θ), calculate the difference a between the measured antenna pattern and the actual distorted antenna pattern of the two-loop channel in a certain test. r (θ)-a di If (θ), then the measurement error of the two-ring channel pattern in a certain measurement can be calculated by the following formula:

[0018] g 2i (θ)cos(θ+π / 4)-a rB (θ)=e 2i (θ)g 2i (θ)cos(θ+π / 4) (3)

[0019] g 3i (θ)sin(θ+π / 4)-a rA (θ)=e 3i (θ)g 3i (θ)sin(θ+π / 4) (4)

[0020] In the formula, g 2i (θ) is the distortion factor of the cosine ring in the i-th measurement, g 3i (θ) is the distortion factor of the sin ring in the i-th measurement, e 2i (θ) is the measurement error coefficient of the cosine ring channel pattern in the i-th measurement, e 3i (θ) is the measurement error coefficient of the sin ring channel pattern in the i-th measurement, where θ is the azimuth angle and π is pi. The right side of the equation is the measurement error of the two ring channel patterns in a certain measurement.

[0021] Furthermore, the specific calculation method for generating the radar's received echo signal from the true distorted radiation pattern in step 3 is as follows:

[0022] X(t)=a r (θ0)S(t)+N(t) (5)

[0023] In the formula, X(t)=[x C (t),x B (t),x A (t)] H x C (t), x B(t), x A (t) represent the echo signals received by the monopole C, ring B, and ring A channels, respectively, where θ0 is the true incident azimuth of the signal, and a r (θ0) is the expression for the true distorted radiation pattern at the θ0 azimuth obtained in step 1, S(t) is the single angle-of-arrival incident signal at the θ0 azimuth, and N(t) = [n C (t),n B (t),n A (t)] H For the noise of each antenna channel, [] H This indicates the conjugate transpose operation.

[0024] The covariance matrix of the received echo signal X(t) from the radar is calculated as follows:

[0025]

[0026] In the formula, Let X be the covariance matrix, X = [X(1), X(2), ... X(j), ..., X(L)], and let X(j) be the received signal matrix of the antenna array, X(j) = [x C (j),x B (j),x A (j)] H ,j=1,2,...,L is the sampling time sequence number, T is the sampling time interval, corresponding to time t=jT, L is the number of snapshots of the echo signal, [ ] H This indicates the conjugate transpose operation.

[0027] For covariance matrix Eigenvalue decomposition yields:

[0028]

[0029] In the formula, Σ is the signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. S It is a diagonal matrix composed of the largest eigenvalues. Σ is the noise subspace spanned by the eigenvectors corresponding to the small eigenvalues. N Let be a diagonal matrix composed of small eigenvalues, [ ] H This represents the conjugate transpose operation. Under single-source conditions, all eigenvalues ​​except the largest eigenvalue are small eigenvalues.

[0030] The expression for the MUSIC spectrum is defined as follows:

[0031]

[0032] In the formula, P represents the MUSIC spectrum, a di(θ) represents the measured antenna pattern obtained from the i-th measurement, where θ is the azimuth angle and I is the identity matrix. Let [ ] be the signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. H This indicates the conjugate transpose operation.

[0033] The angle corresponding to the maximum value of the peak in the MUSIC spectrum is the estimated azimuth angle.

[0034]

[0035] In the formula, a di (θ) represents the measured antenna pattern (guiding vector) obtained from the i-th measurement, where θ is the azimuth angle and I is the identity matrix. Let [ ] be the signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. H This indicates the conjugate transpose operation.

[0036] Furthermore, the azimuth estimation error in step 4 is the direction finding error, and its calculation method is as follows:

[0037]

[0038] In the formula, θ0 is the estimated azimuth angle of the signal obtained in step 3, where θ0 is the true incident azimuth of the signal.

[0039] The present invention also provides a system for measuring the pattern of a monopole / cross-loop antenna and estimating the direction-finding error, for implementing the method for measuring the pattern of a monopole / cross-loop antenna and estimating the direction-finding error as described above.

[0040] Furthermore, it includes a processor and a memory, the memory being used to store program instructions, and the processor being used to call the program instructions in the memory to execute a monopole / cross-loop antenna pattern measurement and direction finding error estimation method as described above.

[0041] Alternatively, it may include a readable storage medium storing a computer program that, when executed, implements a method for measuring the pattern of a monopole / cross-loop antenna and estimating the direction-finding error as described above.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] 1) Compared with existing antenna pattern measurement methods, this invention further considers the influence of measurement error. It can obtain the magnitude of measurement error without modifying existing measurement methods, and is convenient to operate and is not affected by the pattern measurement method.

[0044] 2) Compared with the azimuth estimation method based on the measured radiation pattern of monopole / cross-loop antenna, this invention distinguishes the definition expression of the measured radiation pattern and the true distorted radiation pattern, and estimates the azimuth based on the measured radiation pattern and its measurement error.

[0045] 3) This invention constructs the entire process of estimating the measurement error based on the measured direction pattern and estimating the direction finding error based on the measurement error, providing a new approach to improving radar direction finding accuracy. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating the implementation method of the present invention.

[0047] Figure 2 shows two measured antenna patterns of a radar station provided in an embodiment of the present invention. Figure 2(a) shows the first measured antenna pattern of a radar station provided in an embodiment of the present invention, and Figure 2(b) shows the second measured antenna pattern of a radar station provided in an embodiment of the present invention.

[0048] Figure 3 The results are actual distortion pattern results provided in the embodiments of the present invention.

[0049] Figure 4 The measurement error coefficient result of a measured radiation pattern provided in an embodiment of the present invention.

[0050] Figure 5 The simulation signal azimuth angle estimation (direction finding) error results provided in the embodiments of the present invention.

[0051] Figure 6 This is a histogram showing the statistical distribution of the azimuth estimation (direction finding) error of the simulated signal provided in an embodiment of the present invention. Detailed Implementation

[0052] This invention provides a method and system for measuring the radiation pattern and estimating the direction finding error of a monopole / cross-loop antenna. The technical solution of this invention will be further described below with reference to the accompanying drawings.

[0053] Example 1

[0054] like Figure 1 As shown, this embodiment of the invention provides a method for measuring the radiation pattern and estimating the direction finding error of a monopole / cross-loop antenna, comprising the following steps:

[0055] Step 1: Obtain multiple measurement results of the radar antenna radiation pattern in the actual environment, and calculate the average value of the multiple measured radiation pattern results as the true distorted antenna radiation pattern.

[0056] In a real-world environment, the results of multiple measurements of the radiation pattern of a monopole / cross-loop antenna are defined as follows:

[0057] a di(θ)=[1,g 2i (θ)cos(θ+π / 4),g 3i (θ)sin(θ+π / 4)], i=1,2,3,...,N (1)

[0058] In the formula, a di (θ) represents the measured antenna pattern obtained from the i-th measurement, where θ is the azimuth angle, and g 2i (θ) is the distortion factor of the cosine ring in the i-th measurement, i.e., the amplitude and phase difference of the cosine ring channel relative to the first antenna channel, g 3i (θ) is the distortion factor of the sin ring in the i-th measurement, that is, the amplitude and phase difference of the sin ring channel relative to the first antenna channel, π is pi, and N is the total number of antenna pattern measurements. In this embodiment, N = 2.

[0059] The true distortion pattern of a monopole / cross-loop antenna is calculated using the following formula:

[0060]

[0061] In the formula, a r (θ) represents the true distorted antenna pattern, a di (θ) represents the measured antenna pattern obtained from the i-th measurement, where θ is the azimuth angle and N is the total number of antenna pattern measurements. In this embodiment, N = 2.

[0062] Step 2: Calculate the difference between the measured antenna pattern and the actual distorted antenna pattern of the two-loop channel in a certain measurement to obtain the measurement error of the antenna pattern of the two-loop channel in a certain measurement.

[0063] Based on the definition in step 1, the true distortion pattern of the two-ring channel is obtained as a. rB (θ) and a rA (θ), calculate the difference a between the measured antenna pattern and the actual distorted antenna pattern of the two-loop channel in a certain test. r (θ)-a di If (θ), then the measurement error of the two-ring channel pattern in a certain measurement can be calculated by the following formula:

[0064] g 2i (θ)cos(θ+π / 4)-a rB (θ)=e 2i (θ)g 2i (θ)cos(θ+π / 4) (3)

[0065] g 3i (θ)sin(θ+π / 4)-a rA (θ)=e 3i (θ)g 3i (θ)sin(θ+π / 4) (4)

[0066] In the formula, g 2i (θ) is the distortion factor of the cosine ring in the i-th measurement, g 3i (θ) is the distortion factor of the sin ring in the i-th measurement, e 2i (θ) is the measurement error coefficient of the cosine ring channel pattern in the i-th measurement, e 3i (θ) is the measurement error coefficient of the sin ring channel pattern in the i-th measurement, where θ is the azimuth angle and π is pi. The right side of the equation is the measurement error of the two ring channel patterns in a certain measurement.

[0067] As mentioned above, based on the mathematical theory of "taking the average of multiple measurements as the true value", the actual true distortion pattern can be obtained from multiple measurements by any pattern measurement method. The difference between the true distortion pattern and the measured pattern is the magnitude of the measurement error. Knowing the true distortion pattern and the measured pattern, the MUSIC algorithm can be used to estimate the azimuth angle, and then the magnitude of the direction finding error can be calculated based on the measurement error.

[0068] Step 3: Generate radar received echo signals based on the actual distorted radiation pattern. Using a measured radiation pattern, estimate the azimuth angle of the received echo signals in any direction using a multi-signal classification algorithm.

[0069] The radar's received echo signal is generated from the true distorted radiation pattern, and the specific calculation method is as follows:

[0070] X(t)=a r (θ0)S(t)+N(t) (5)

[0071] In the formula, X(t)=[x C (t),x B (t),x A (t)] H x C (t), x B (t), x A (t) represent the echo signals received by the monopole C, ring B, and ring A channels, respectively, where θ0 is the true incident azimuth of the signal, and a r (θ0) is the expression for the true distorted azimuth pattern (guidance vector) at the θ0 azimuth obtained in step 1, S(t) is the single angle-of-arrival incident signal at the θ0 azimuth, and N(t) = [n C (t),n B (t),n A (t)] H For the noise of each antenna channel, [] H This indicates the conjugate transpose operation.

[0072] The covariance matrix of the received echo signal X(t) from the radar is calculated as follows:

[0073]

[0074] In the formula, Let X be the covariance matrix, X = [X(1), X(2), ... X(j), ..., X(L)], and let X(j) be the received signal matrix of the antenna array, X(j) = [x C (j),x B (j),x A (j)] H j = 1, 2, ..., L is the sampling time sequence number, T is the sampling time interval, corresponding to time t = jT, and L is the number of snapshots of the echo signal. In this embodiment, L = 300. H This indicates the conjugate transpose operation.

[0075] For covariance matrix Eigenvalue decomposition yields:

[0076]

[0077] In the formula, Σ is the signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. S It is a diagonal matrix composed of the largest eigenvalues. Σ is the noise subspace spanned by the eigenvectors corresponding to the small eigenvalues. N Let be a diagonal matrix composed of small eigenvalues, [ ] H This represents the conjugate transpose operation. Under single-source conditions, all eigenvalues ​​except the largest eigenvalue are small eigenvalues.

[0078] The expression for the MUSIC spectrum is defined as follows:

[0079]

[0080] In the formula, P represents the MUSIC spectrum, a di (θ) represents the measured antenna pattern obtained from the i-th measurement, where θ is the azimuth angle and I is the identity matrix. Let [ ] be the signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. H This indicates the conjugate transpose operation.

[0081] The angle corresponding to the maximum value of the peak in the MUSIC spectrum is the estimated azimuth angle.

[0082]

[0083] In the formula, a di(θ) represents the measured antenna pattern (guiding vector) obtained from the i-th measurement, where θ is the azimuth angle and I is the identity matrix. Let [ ] be the signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. H This indicates the conjugate transpose operation.

[0084] Step 4: Calculate the difference between the azimuth angle estimation result of any azimuth echo signal described in Step 3 and the true azimuth angle to obtain the magnitude of the azimuth angle estimation error.

[0085] The azimuth estimation error is the same as the direction finding error, and its calculation method is as follows:

[0086]

[0087] In the formula, θ0 is the estimated azimuth angle of the signal obtained in step 3, where θ0 is the true incident azimuth of the signal.

[0088] Figure 2(a) and Figure 2(b) show the results of two measurements of the antenna pattern of a radar station provided in an embodiment of the present invention. Figure 3 The true distorted antenna pattern obtained using the method proposed in this invention is obtained by averaging the measurement results of Figure 2(a) and Figure 2(b). Figure 4 The measurement error coefficient of a measured radiation pattern obtained using the method proposed in this invention is concentrated between -0.1 and 0.1, with a small number of azimuths approaching ±0.3, indicating that the overall measurement accuracy of the radiation pattern is high and the measurement error is not significant. Figure 5 and Figure 6 This paper presents the estimation (direction finding) errors and their distribution in different azimuths. The distortion factors of the two-ring antenna differ in different azimuths, resulting in varying measurement errors. The impact of these measurement errors on angle estimation varies. When the distortion factor is very small, even a small measurement error can significantly affect angle estimation; conversely, when the distortion factor is large, only a sufficiently large measurement error will have a significant impact. If an angle estimation error of less than 10 degrees is defined as good, this probability is 67.22% in this embodiment. This indicates that the direction finding error is small in most azimuths, but larger in a few azimuths due to the greater influence of measurement errors.

[0089] Example 2

[0090] Based on the same inventive concept, the present invention also provides a monopole / cross-loop antenna pattern measurement and direction finding error estimation system, including a processor and a memory. The memory is used to store program instructions, and the processor is used to call the program instructions in the memory to execute the monopole / cross-loop antenna pattern measurement and direction finding error estimation method as described above.

[0091] Example 3

[0092] Based on the same inventive concept, the present invention also provides a monopole / cross-loop antenna pattern measurement and direction finding error estimation system, including a readable storage medium on which a computer program is stored. When the computer program is executed, it implements the monopole / cross-loop antenna pattern measurement and direction finding error estimation method as described above.

[0093] In specific implementation, the method proposed in the technical solution of this invention can be automatically executed by those skilled in the art using computer software technology. System devices for implementing the method, such as computer-readable storage media storing the corresponding computer program of the technical solution of this invention and computer equipment including the computer program running the corresponding computer program, should also be within the protection scope of this invention.

[0094] The embodiments described herein use two measured radiation pattern results; three or more measurements can yield a more accurate true distortion radiation pattern. The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for estimating the radiation pattern measurement error and direction finding error of a monopole cross-loop antenna, characterized in that, Includes the following steps: Step 1: Obtain multiple measurement results of the radar antenna radiation pattern in the actual environment, and calculate the average value of the multiple measured radiation pattern results as the true distorted antenna radiation pattern. Step 2: Calculate the difference between the measured antenna pattern and the actual distorted antenna pattern of the two-loop channel in a certain measurement to obtain the measurement error of the antenna pattern of the two-loop channel in a certain measurement. Step 3: Generate radar received echo signal based on the actual distorted antenna pattern. Using a measured pattern, estimate the azimuth of the received echo signal in any direction using a multi-signal classification algorithm. Step 4: Calculate the difference between the azimuth angle estimation result of any azimuth echo signal described in Step 3 and the true azimuth angle to obtain the magnitude of the azimuth angle estimation error.

2. The method for estimating the radiation pattern measurement error and direction finding error of a monopole cross-loop antenna as described in claim 1, characterized in that: The results of multiple measurements of the radiation pattern of a monopole / cross-loop antenna in the actual environment in step 1 are defined as follows: （1） In the formula, Indicates the first i The measured antenna pattern obtained from this measurement. It is the azimuth angle. For the first i The distortion factor of the cosine ring in this measurement, i.e., the amplitude and phase difference of the cosine ring channel relative to the first antenna channel. For the first i The distortion factor of the sine ring in this measurement, that is, the amplitude and phase difference of the sine ring channel relative to the first antenna channel. Pi N This represents the total number of antenna pattern measurements.

3. The method for estimating the radiation pattern measurement error and direction finding error of a monopole cross-loop antenna as described in claim 2, characterized in that: The true distorted antenna pattern of the monopole / cross-loop antenna in step 1 is calculated by the following formula: （2） In the formula, This is the actual distorted antenna pattern. Indicates the first i The measured antenna pattern obtained from this measurement. It is the azimuth angle. N This represents the total number of antenna pattern measurements.

4. The method for estimating the radiation pattern measurement error and direction finding error of a monopole cross-loop antenna as described in claim 1, characterized in that: In step 2, the true distorted antenna pattern of the two-ring channel is obtained according to the definition in step 1. and Calculate the difference between the measured antenna pattern and the actual distorted antenna pattern of the two-loop channel for each measurement. The measurement error of the two-ring channel orientation pattern in a certain measurement can be calculated by the following formula: （3） （4） In the formula, For the first i The distortion factor of the cosine ring in this measurement. For the first i The distortion factor of the sine ring in this measurement. For the first i The measurement error coefficient of the cosine ring channel pattern in this measurement. For the first i The measurement error coefficient of the sin loop channel pattern in this measurement. It is the azimuth angle. Let π be the value of a circle, and the right side of the equation represents the measurement error of the two-ring channel orientation pattern in a certain measurement.

5. The method for estimating the pattern measurement error and direction finding error of a monopole cross-loop antenna as described in claim 1, characterized in that: In step 3, the radar's received echo signal is generated from the actual distorted antenna pattern. The specific calculation method is as follows: （5） In the formula, , , , These are the echo signals received by the monopole C, ring B, and ring A channels, respectively. This represents the true incident direction of the signal. To utilize the results obtained in step 1 The expression for the true azimuth distortion antenna pattern. for Single angle of arrival incident signal in azimuth, For the noise of each antenna channel, This indicates the conjugate transpose operation.

6. The method for estimating the radiation pattern measurement error and direction finding error of a monopole cross-loop antenna as described in claim 5, characterized in that: Step 3 calculates the radar's received echo signal. The covariance matrix is: （6） In the formula, Let covariance matrix be the variance matrix. For the antenna array receiving signal matrix, This is the sampling time sequence number. The sampling time interval is [time value], corresponding to the time [time value]. , L The number of snapshots of the echo signal. This represents the conjugate transpose operation; For covariance matrix Eigenvalue decomposition yields: （7） In the formula, The signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. It is a diagonal matrix composed of the largest eigenvalues. The noise subspace spanned by the eigenvectors corresponding to the small eigenvalues. It is a diagonal matrix composed of small eigenvalues. This represents the conjugate transpose operation. Under single-source conditions, all eigenvalues ​​except the largest eigenvalue are small eigenvalues.

7. The method for estimating the radiation pattern measurement error and direction finding error of a monopole cross-loop antenna as described in claim 6, characterized in that: In step 3, the expression for the MUSIC spectrum is defined as follows: （8） In the formula, P represents the MUSIC spectrum. Indicates the first i The measured antenna pattern obtained from this measurement. It is the azimuth angle. I It is the identity matrix. The signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. This represents the conjugate transpose operation; The angle corresponding to the maximum value of the peak in the MUSIC spectrum is the estimated azimuth angle. : （9） In the formula, For the first i The measured antenna pattern obtained from this measurement. It is the azimuth angle. I It is the identity matrix. The signal subspace spanned by the eigenvectors corresponding to the largest eigenvalue. This indicates the conjugate transpose operation.

8. The method for estimating the radiation pattern measurement error and direction finding error of a monopole cross-loop antenna as described in claim 1, characterized in that: In step 4, the azimuth estimation error is the direction finding error, and its calculation method is as follows: （10） In the formula, The azimuth angle estimate of the signal obtained in step 3 is... This represents the true incident direction of the signal.

9. A system for measuring the radiation pattern and estimating the direction finding error of a monopole / cross-loop antenna, characterized in that, It includes a processor and a memory, the memory being used to store program instructions, and the processor being used to call the program instructions in the memory to execute the method for measuring the pattern of a monopole / cross-loop antenna and estimating the direction finding error as described in any one of claims 1-8.

10. A system for measuring the radiation pattern and estimating the direction finding error of a monopole / cross-loop antenna, characterized in that, The device includes a readable storage medium on which a computer program is stored, and when the computer program is executed, it implements a method for measuring the pattern of a monopole / cross-loop antenna and estimating the direction-finding error as described in any one of claims 1-8.

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