Wideband planar array multi-beam forming method and amplitude comparison angle finding method

Abstract

The application discloses a broadband planar array multi-beam forming method and an amplitude ratio angle measurement method. The broadband planar array multi-beam forming method comprises the following steps: in a spatial rectangular coordinate system, a normalized space frequency model is established; uniform frequency sampling is performed on two-dimensional space DFT, and a beam forming coefficient is designed according to the uniform frequency sampling; digital acquisition signals of each array element of the broadband planar array are obtained, and multi-beam forming calculation is performed based on the designed beam forming coefficient; and the multi-beam forming result is subjected to two-dimensional joint detection of space and frequency, and frequency, beam number and adjacent beam amplitude information of the detected signal are output. The amplitude ratio angle measurement method comprises the following steps: an amplitude ratio table corresponding to the normalized space frequency is established based on the beam forming coefficient; the amplitude ratio table is subjected to matching processing according to the amplitude information of the multi-beam detected signal, and the normalized space frequency value is estimated; and the incident two-dimensional angle of the signal is solved based on the normalized space frequency model.

Description

Technical Field

[0001] This invention belongs to the field of passive radar detection technology, and particularly relates to a broadband planar array multi-beamforming method and an amplitude-to-angle measurement method. Background Technology

[0002] Passive radar does not emit electromagnetic signals itself; instead, it detects and identifies targets by intercepting radar signals from the target's radiation source. Because it does not require active energy transmission, passive radar has advantages such as high stealth and good security.

[0003] In order to achieve high-sensitivity interception and high-precision direction finding of radiation sources in a wide bandwidth and wide airspace, broadband digital array systems based on digital multibeamforming and cross amplitude angle measurement technologies are widely used in the field of passive radar.

[0004] Broadband planar arrays for high-precision two-dimensional direction finding often borrow the processing approach of one-dimensional direction finding systems, handling azimuth amplitude comparison and elevation amplitude comparison separately. Chinese Patent Publication No. CN114236465A discloses a search-based two-dimensional high-precision amplitude comparison direction finding method and apparatus, which uses separate azimuth and elevation direction finding antenna arrays. Each array calculates the corresponding one-dimensional angle based on the relationship between the power difference of the direction finding beams at different frequencies and the incident angle (i.e., the amplitude comparison curve). The amplitude comparison curves differ between different frequencies and different directional beams. Chinese Patent Publication No. CN113866709A discloses a phased array cross-beam amplitude comparison direction finding method. This scheme uses digital beamforming (DBF) to construct multiple beams simultaneously in the azimuth direction of the search space. In the elevation direction, it divides the array into left and right halves and uses analog beamforming (ABF) to construct dual beams. It calculates the amplitude difference table between adjacent beams in azimuth and elevation respectively. At the same time, by designing a constant beamwidth beamformer, the array has the same beam pattern for input signals of different frequencies, thereby simplifying the design of the amplitude comparison curve.

[0005] Designing separate azimuth and elevation antenna arrays, the lack of full array data utilization in their respective beamforming processes negatively impacted the system signal gain. Since the beamforming response of a broadband planar array is a function of frequency, azimuth, and elevation, the design of beamforming coefficients and amplitude ratio curves needs to cover processing for different frequencies and beam directions (azimuth and elevation). Patent CN114236465A requires calculating and storing amplitude ratio parameters between beams of different frequencies and directions, resulting in a large data volume. Patent CN113866709A requires designing a set of frequency-varying amplitude weighting coefficients for array elements to ensure the same main lobe width for beams at different frequencies. Therefore, the beamforming coefficient design is more complex, and different array element amplitude weighting coefficients can lead to differences in the detection performance of different beams.

[0006] In summary, existing beamforming and two-dimensional amplitude comparison direction finding methods suffer from problems such as insufficient utilization of array data, complex beamforming coefficient or amplitude comparison curve design, and inconsistent detection performance of different beams. These methods cannot fully meet the high-precision two-dimensional amplitude comparison direction finding requirements for wide-bandwidth, multi-beam, and wide-spatial-area coverage. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art by providing a broadband planar array multi-beamforming method and an amplitude comparison angle measurement method, which can simultaneously perform broadband planar array beamforming and two-dimensional amplitude comparison angle measurement for azimuth and elevation.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for forming a broadband planar array multibeamforming includes the following steps:

[0010] In a spatial rectangular coordinate system, determine the position coordinates of each array element, establish a normalized spatial frequency model, and design beamforming coefficients through homogenized frequency sampling analysis of two-dimensional spatial DFT.

[0011] The digital acquisition signals of each element of the broadband planar array are transformed into multiple narrowband amplitude and phase signals. Multi-beamforming processing is completed based on the beamforming coefficients. For the amplitude data of the multi-beamforming, spatial and frequency domain rate joint detection is performed, and relevant information of the detection signal is output. The detection signal is a spatial and frequency domain peak signal with an amplitude exceeding a preset threshold. The relevant information includes frequency, beam number, the beam it belongs to, and the amplitude information of adjacent beams.

[0012] Furthermore, the normalized spatial frequency model expression includes:

[0013]

[0014]

[0015] Where ω is the spatial frequency in the azimuth dimension, and τ is the spatial frequency in the elevation dimension. Let θ be the elevation angle of the incident signal, λ be the azimuth angle of the incident signal, λ be the wavelength of the incident signal, and d be a value not less than half the wavelength of the highest operating frequency.

[0016] Furthermore, the beamforming process is described by homogenized frequency domain sampling using two-dimensional spatial DFT:

[0017]

[0018] Among them, (D) nx D nyLet ω be the position coordinates of array element n, x(n) be the complex signal of array element n at a certain narrowband frequency, and ω be the position coordinates of array element n. m For the homogenized azimuth-dimensional spatial frequency sampling points of the spatial DFT, τ l For the uniform pitch-dimensional spatial frequency sampling points of the spatial DFT, A n Y(ω) is the magnitude weighting coefficient of the array data. m ,τ l () represents the beamforming result.

[0019] Furthermore, the density of the frequency domain sampling of the two-dimensional spatial DFT homogenization determines the density of beam superposition; the amplitude weighting coefficient of each element determines the array gain, main lobe width, and main-to-side lobe ratio of the beam. Using the same amplitude weighting coefficient for each beam can obtain consistent beam index parameters; the phase weighting coefficient of each element is calculated by compensating for the phase difference between the beam pointing and each element.

[0020] Furthermore, the method performs signal detection through joint detection processing of the spatial and frequency dimensions, and outputs relevant information, including the frequency, beam number, beam of the detected signal, and amplitude information of adjacent beams.

[0021] On the other hand, the present invention also provides an amplitude-based angle measurement method, which is used to calculate the two-dimensional angle of the detection signal generated by any of the aforementioned methods, and includes the following steps:

[0022] Based on the multibeams generated by the two-dimensional spatial DFT homogenized frequency sampling, the relationship between the normalized spatial frequency and the amplitude ratio of adjacent beams is calculated, and an amplitude ratio table is established.

[0023] Using the amplitude ratio table and relevant information of the detection signal, the normalized spatial frequency of the detection signal is estimated.

[0024] The radio frequency value corresponding to the signal is determined based on the system frequency transformation relationship, and then the two-dimensional incident angle of the signal is calculated by the normalized spatial frequency estimate according to the normalized spatial frequency model.

[0025] Furthermore, the method stores only one table of amplitude ratios between spatial frequency sampling intervals.

[0026] Furthermore, the process of normalized spatial frequency estimation includes:

[0027] The normalized spatial frequency offset value is determined based on the amplitude ratio table and the relevant information of the detection signal, and the corresponding normalized spatial frequency is calculated from the beam in which the detection signal is located, thereby obtaining the normalized spatial frequency estimate of the radiation source signal.

[0028] Furthermore, the method also includes obtaining the optimal spatial frequency offset value using an optimized estimation model, wherein the optimized estimation model is:

[0029]

[0030] Where c1, c2, and c3 are the beams (ω) p+1 ,τ q ), (ω p ,τ q+1 ), (ω p+1 ,τ q+1 ) relative to the beam (ω) p ,τ q The amplitude ratio of (Δω,Δτ) represents the spatial frequency offset value, (ω p ,τ q Y(ω) represents the normalized spatial frequency. p ,τ q The beamforming result is represented by , and the normalized spatial frequency estimate is:

[0031]

[0032]

[0033] Furthermore, the process of calculating the two-dimensional incident angle of the signal includes:

[0034] Based on the intermediate frequency of the detected signal, it is converted into a radio frequency value. Then, using the estimated normalized spatial frequency value and the normalized spatial frequency model, the two-dimensional incident angle of the signal is calculated.

[0035] The beneficial effects of this invention are as follows:

[0036] (1) All array elements of the planar array of the present invention participate in digital beamforming calculation, which improves the array gain.

[0037] (2) The beamforming method of the present invention designs uniform amplitude weighting coefficients for each array element for each beam, so that the same array gain and main-side lobe ratio are available for beams of different frequencies and directions, and the gain is the same at the overlap of all adjacent beams, so that the system has relatively consistent detection performance for radiation source signals of various incident angles and frequencies.

[0038] (3) The present invention uses the same array element amplitude weighting coefficient for beamforming processing of different frequencies and directions, while the phase weighting coefficient is easy to calculate based on the phase difference to be compensated according to the beam direction, which simplifies the beamforming coefficient design.

[0039] (4) This invention differs from the traditional direct amplitude comparison angle measurement method. The amplitude ratio table established in this invention is used to estimate the normalized spatial frequency of the incident signal. By sampling the uniform frequency of the two-dimensional spatial DFT, the beam amplitude response is periodic relative to the azimuth and elevation spatial frequencies and is independent of the signal frequency. Only one complete period of amplitude ratio curve needs to be stored to complete the two-dimensional angle measurement of various incident angles and frequency signals, which greatly simplifies the design and storage of amplitude ratio curves.

[0040] (5) The beamforming coefficient and amplitude ratio curve designed in this invention do not have large interpolation approximation processing, which can better guarantee the angle measurement accuracy. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the specific processing flow for broadband planar array multi-beamforming provided in Embodiment 1 of the present invention;

[0042] Figure 2 This is a schematic diagram of the specific processing flow of broadband planar array multi-beam amplitude and angle measurement provided in Embodiment 2 of the present invention;

[0043] Figure 3 This is the overall flowchart of Embodiment 3 of the present invention;

[0044] Figure 4 This is a schematic diagram of the specific processing flow of Embodiment 3 of the present invention;

[0045] Figure 5 This is a diagram showing the element position distribution of a non-uniformly spaced broadband planar array according to Embodiment 3 of the present invention;

[0046] Figure 6 This is embodiment 3 of the present invention. Figure 5 The simulated antenna pattern of the array shown;

[0047] Figure 7 This is Embodiment 3 of the present invention at a frequency of 6GHz. Figure 5 The antenna pattern of the array simulation shown;

[0048] Figure 8 This is Embodiment 3 of the present invention at a frequency of 2.4 GHz. Figure 5 The antenna pattern of the array simulation is shown. Detailed Implementation

[0049] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0050] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Existing beamforming and two-dimensional amplitude comparison direction finding methods suffer from problems such as insufficient utilization of array data, complex beamforming coefficient or amplitude comparison curve design, and inconsistent detection performance of different beams. They cannot fully meet the high-precision two-dimensional amplitude comparison direction finding requirements of wide-band, multi-beam wide-spatial coverage.

[0052] To address the aforementioned technical problems, the following embodiments of the broadband planar array multi-beamforming method and amplitude comparison angle measurement method of the present invention are proposed.

[0053] Example 1

[0054] Reference Figure 1 ,like Figure 1 The diagram shown is a schematic representation of the specific processing flow for broadband planar array multi-beamforming provided in this embodiment. The method specifically includes the following steps:

[0055] Step 1, establish a two-dimensional spatial frequency model: In a spatial rectangular coordinate system, based on the actual position coordinates of each element of the broadband planar array, establish a mathematical description of the normalized spatial frequency (including the spatial frequency in the azimuth dimension and the spatial frequency in the elevation dimension).

[0056] Step 2, Beamforming Design Based on Two-Dimensional Spatial DFT: The beamforming process is described using two-dimensional spatial DFT. The homogenized frequency sampling output of the two-dimensional spatial DFT is the beamforming result of each beam. Based on specific application requirements, beamforming coefficients are determined through simulation analysis, and a uniform amplitude weighting coefficient is used for each array data element. The density of the homogenized frequency domain sampling in the two-dimensional spatial DFT determines the beam superposition density; the amplitude weighting coefficient of each array data element determines the array gain, main lobe width, and main-side lobe ratio of the beam. Using the same amplitude weighting coefficient for each beam ensures consistent beam performance parameters. The phase weighting coefficient of each array data element is determined by calculating the phase difference that needs to be compensated for in beam pointing.

[0057] Step 3, Real-time multi-beamforming calculation and processing: The signals acquired by each element of the broadband planar array are converted into multiple narrowband amplitude and phase signals. Based on the beamforming coefficients designed in Step 2, real-time multi-beamforming calculation and processing is performed to generate simultaneous multi-beam amplitude and phase data.

[0058] Step 4: Joint detection and processing of signal in spatial and frequency domains: For the amplitude data of multi-beamforming, joint peak search processing is performed in the spatial and frequency domains (i.e., the effective detection signal must be at the peak value in both the frequency and beam dimensions), and if the amplitude exceeds the preset threshold, a detection signal is generated and relevant information including frequency, beam number, the beam it is in, and amplitude information of adjacent beams is output.

[0059] The broadband planar array multi-beamforming method provided in this embodiment involves all array elements of the planar array participating in digital beamforming calculations, thereby improving array gain. A unified amplitude weighting coefficient is designed for each array element, ensuring the same array gain and main-side lobe ratio for beams of different frequencies and directions. The gain is also identical at the overlap of all adjacent beams, resulting in relatively consistent detection performance for radiation source signals of various incident angles and frequencies. The same array element amplitude weighting coefficients are used for beamforming processing of different frequencies and directions, while the phase weighting coefficients are easily calculated based on the phase difference to be compensated according to the beam direction, simplifying beamforming coefficient design.

[0060] Example 2

[0061] Reference Figure 2 ,like Figure 2 The diagram shown is a schematic of the broadband planar array multi-beam amplitude and angle measurement process provided in this embodiment. This process is used to calculate the two-dimensional angle of the detection signal generated by the aforementioned broadband planar array multi-beamforming method, and specifically includes the following steps:

[0062] Step 1: Establish an amplitude ratio table corresponding to the normalized spatial frequency offset value: Based on the multi-beam design using uniform frequency sampling in two-dimensional spatial DFT, each frequency sampling value corresponds to the normalized spatial frequency of each beam direction. The incident angle of any signal also corresponds to a normalized spatial frequency value. The mapping relationship between the normalized spatial frequency offset value (the offset relative to the normalized spatial frequency value pointed to by the neighboring beam) corresponding to the incident angle and the amplitude ratio of the adjacent beams can be calculated, thereby establishing an amplitude ratio table. The beam amplitude response output by the two-dimensional spatial DFT is periodic relative to the normalized spatial frequency, so only an amplitude ratio table between spatial and frequency sampling intervals needs to be stored.

[0063] Step 2, estimate the normalized spatial frequency value of the signal: Based on the relevant information of the input detected signal and the existing amplitude ratio table, estimate the normalized spatial frequency offset value of the detected signal by looking up the table or by optimizing the estimation method. Combined with the normalized spatial frequency corresponding to the direction of the adjacent beam, estimate the normalized spatial frequency value corresponding to the incident angle.

[0064] Step 3, calculate the incident two-dimensional angle of the signal: The signal frequency directly obtained in the signal detection stage is generally the intermediate frequency value. It needs to be converted into the radio frequency value according to the system frequency transformation relationship. Then, according to the normalized spatial frequency model, the true two-dimensional angle (i.e., azimuth and elevation) of the incident signal is calculated.

[0065] The amplitude ratio angle measurement method provided in this embodiment differs from the traditional direct amplitude ratio angle measurement method. The amplitude ratio table established in this invention is first used to estimate the normalized spatial frequency of the incident signal, and then indirectly solves for the two-dimensional spatial angle. Based on the multi-beam design using uniform frequency sampling in two-dimensional spatial DFT, the beam amplitude response exhibits periodicity relative to the azimuth and elevation spatial frequencies, and is independent of the signal frequency. Only one complete cycle of the amplitude ratio curve needs to be stored to complete two-dimensional angle measurement for signals with various incident angles and frequencies, greatly simplifying the design and storage of the amplitude ratio curve. Furthermore, without any interpolation approximation processing, the accuracy of the angle measurement can be guaranteed.

[0066] Example 3

[0067] This embodiment provides a complete implementation flow of a multi-beamforming and amplitude-comparison angle measurement method for broadband planar arrays. Figure 3 This is the overall flowchart of this embodiment.

[0068] Figure 4 This is a flowchart illustrating the specific processing steps of this embodiment, which include the following steps:

[0069] Step 1: Select a reference element as the origin, establish a spatial rectangular coordinate system, and determine the coordinate position P of each element. n (D nx D ny Then, based on the array's operating frequency range, the half-wavelength d of the highest operating frequency is selected as the reference element spacing, thereby establishing a normalized spatial frequency model:

[0070]

[0071]

[0072] Where ω is the spatial frequency in the azimuth dimension, and τ is the spatial frequency in the elevation dimension. Let d be the elevation angle of the incident signal, θ be the azimuth angle of the incident signal, and λ be the wavelength of the incident signal. Clearly, for d ≤ λ / 2, θ ∈ [-π / 2, π / 2], There are -π≤ω≤π and -π≤τ≤π.

[0073] Step 2: Each array element acquires signals, which are then corrected and transformed. Assuming the amplitude and phase signal at a certain frequency is represented as x(n) (where n = 0, 1, 2, ..., N-1, and the planar array has a total of N array elements), the beamforming process of the planar array can be represented by two-dimensional spatial DFT as follows:

[0074] m=0,1,2,…,M-1; l=0,1,2,…,L-1

[0075] ω m =m*2π / M-π,m=0,1,2,…,M-1

[0076] τ l =l*2π / L-π,l=0,1,2,…,L-1

[0077] Where, ω m For the homogenized azimuth-dimensional spatial frequency sampling points of the spatial DFT, τ l For the uniform pitch-dimensional spatial frequency sampling points of the spatial DFT, A n Y(ω) is the magnitude weighting coefficient of the array data. m ,τ l The image shows the beamforming result. Parameters M and L determine the beam density in the azimuth and elevation dimensions, respectively. The denser the beams, the higher the gain at the overlap of adjacent beams. The values ​​of parameters M and L can be determined according to specific application requirements. The amplitude weighting coefficient A for each array data element... n The array gain, main lobe width, and main-to-side lobe ratio of the beam are determined and can be selected through optimization analysis based on system requirements. The calculation of the phase weighting coefficients for each element requires compensating for the phase difference of the beam pointing to each element, which can obviously be calculated using ω. m τ l The coordinates of the array elements are used to determine the position.

[0078] Step 3: Based on the beamforming coefficients determined in Step 2, select a spatial frequency range within one frequency domain sampling interval of the spatial DFT, simulate the incident signal, and calculate the relationship between the normalized spatial frequency offset and the amplitude ratio of adjacent beams; for example, the simulated incident signal spatial frequency ω∈[ω m ,ω m+1 ] and τ∈[τ l ,τ l+1 ] Calculate the amplitude ratio |Y(ω) between adjacent beams m+1 ,τ l)| / |Y(ω m ,τ l )|、|Y(ω m ,τ l+1 )| / |Y(ω m ,τ l )|、|Y(ω m+1 ,τ l+1 )| / |Y(ω m ,τ l )|, thereby establishing its relationship with the spatial frequency shift (Δω=ω-ω m Δτ=τ-ω l The beam amplitude response of the two-dimensional spatial DFT output is periodic relative to the azimuth and elevation spatial frequencies. Therefore, the values ​​of this amplitude ratio table are the same for different beams, and only one copy needs to be stored.

[0079] Step 4: The signals acquired by each element of the broadband planar array are converted into multi-frequency amplitude and phase signals through FFT spectrum calculation and correction. Based on the beamforming coefficients and beam pointing determined in Step 2, multi-beam calculation is completed. Then, peak search is performed along both beam and frequency dimensions. A detection algorithm is used to detect beam signals with large amplitudes and record information such as the frequency (usually the intermediate frequency), beam position, amplitude of the beam, and amplitude of adjacent beams.

[0080] Step 5: Based on the amplitude ratio table established in Step 3 and the relevant information of the detected signal output in Step 4, the normalized spatial frequency offset value (Δω, Δτ) is determined through optimization calculation. Using the beam position of the detected signal output in Step 4, the normalized spatial frequency (ω) corresponding to the beam direction can be calculated. p ,τ q This allows us to obtain the normalized spatial frequency estimate of the radiation source signal.

[0081]

[0082]

[0083] An optimized estimation model for the normalized spatial frequency offset (Δω, Δτ) is as follows:

[0084]

[0085] Where c1, c2, and c3 are the beams (ω) p+1 ,τ q ), (ω p ,τ q+1 ), (ω p+1 ,τ q+1 ) relative to the beam (ω) p,τ q The amplitude ratios of the amplitude ratios are corresponding one-to-one with the normalized spatial frequency offset values ​​(Δω, Δτ) in the amplitude ratio table established in step 3. Based on the aforementioned optimization objective function, the optimal normalized spatial frequency offset values ​​(Δω, Δτ) can be matched by searching the amplitude ratio coefficients c1, c2, and c3.

[0086] Step 6: Based on the detected signal frequency value output in Step 4, and according to the system frequency transformation relationship, obtain its corresponding radio frequency value f. Then, using the normalized spatial frequency estimate output in Step 5, calculate the true two-dimensional angle of the radiation source signal according to the spatial frequency calculation model determined in Step 1.

[0087]

[0088]

[0089] Where c represents the speed of light.

[0090] Figure 5 This is a diagram showing the position coordinates of each element in the broadband planar array used in the simulation analysis of Example 3. For example... Figure 5 As shown, the array contains 22 elements. Figure 6 Yes Figure 5 The antenna pattern obtained from array simulation (relative to normalized spatial frequency). For ease of demonstration, the antenna pattern responses of all beams have been maximized. Figure 6 As can be seen, the total amplitude response of different beams varies along the normalized spatial frequency and has periodicity. The main performance characteristics of different beams (including main lobe width, main-to-side lobe ratio, and gain at beam overlap) are exactly the same. Therefore, it is only necessary to store a set of amplitude ratio curves between beams to estimate the normalized spatial frequency, thereby indirectly solving for the azimuth and elevation angles. Figure 7 Yes Figure 5 The antenna pattern (relative to azimuth and elevation angles) was simulated for a 6 GHz incident frequency signal. Figure 8 Yes Figure 5 The antenna pattern (relative to azimuth and elevation angles) was simulated for an incident frequency signal of 2.4 GHz. Figure 7 and Figure 8 For ease of demonstration, the antenna pattern response of all beams has been maximized. For example... Figure 7 and Figure 8As shown, within the broadband range, the antenna patterns calculated relative to the azimuth and elevation angles differ greatly for different incident signal frequencies. Furthermore, the antenna patterns for different directional beams at the same frequency also differ (starting from the center beam, the main lobe of the beams closer to the edge is wider). Therefore, using the traditional direct amplitude comparison angle measurement method, the receiver must store all these different amplitude comparison curves, which is highly complex. However, the amplitude comparison angle measurement method used in this embodiment solves this problem well.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for amplitude-based angle measurement, characterized in that, The amplitude-to-angle measurement method is used to calculate the two-dimensional angle of the detection signal generated by the broadband planar array multi-beamforming method. The broadband planar array multi-beamforming method includes the following steps: determining the position coordinates of each array element in a spatial rectangular coordinate system, establishing a normalized spatial frequency model, and designing beamforming coefficients through homogenized frequency sampling analysis of two-dimensional spatial DFT; transforming the digitally acquired signals of each array element of the broadband planar array into multiple narrowband amplitude and phase signals, completing multi-beamforming processing based on the beamforming coefficients, and performing joint detection of the spatial and frequency dimensions on the amplitude data of the multi-beamformation, outputting relevant information of the detection signal. The detection signal is a spatial-frequency domain peak signal with an amplitude exceeding a preset threshold. The relevant information includes frequency, beam number, the beam it belongs to, and amplitude information of adjacent beams. The amplitude-to-angle measurement method includes: Based on the multibeams generated by the two-dimensional spatial DFT homogenized frequency sampling, the relationship between the normalized spatial frequency offset value and the amplitude ratio of adjacent beams is calculated, and an amplitude ratio table is established. Using the amplitude ratio table and relevant information of the detection signal, the normalized spatial frequency of the detection signal is estimated. The radio frequency value corresponding to the detection signal is determined based on the system frequency transformation relationship. Then, the two-dimensional incident angle of the detection signal is calculated from the normalized spatial frequency estimate according to the normalized spatial frequency model.

2. The amplitude comparison angle measurement method as described in claim 1, characterized in that, The normalized spatial frequency model expression includes: in, For the spatial frequency in the azimuth dimension, For the spatial frequency in the pitch dimension, The elevation angle of the incident signal. The azimuth angle of the incident signal. The wavelength of the incident signal, For reference element spacing, Not greater than half the wavelength of the highest operating frequency.

3. The amplitude comparison angle measurement method as described in claim 1, characterized in that, The beamforming process is described by homogenized frequency domain sampling using two-dimensional spatial DFT: in, For array element Location coordinates, For array element A complex signal at a certain narrowband frequency For the homogenized azimuth-dimensional spatial frequency sampling points of the spatial DFT, For the uniform pitch-dimensional spatial frequency sampling points of the spatial DFT, The magnitude weighting coefficients for the array data. For beamforming results, The reference element spacing is N, where N is the total number of elements in the planar array, and n is the element number.

4. The amplitude comparison angle measurement method as described in claim 3, characterized in that: The density of the frequency domain sampling homogenized by the two-dimensional spatial DFT determines the density of beam superposition; the amplitude weighting coefficient of each element determines the array gain, main lobe width, and main-to-side lobe ratio of the beam. Using the same amplitude weighting coefficient for each beam can obtain consistent beam index parameters; the phase weighting coefficient of each element is calculated by compensating for the phase difference between the beam pointing and each element.

5. The amplitude comparison angle measurement method as described in claim 1, characterized in that, The method stores only one table of amplitude ratios between spatial frequency sampling intervals.

6. The amplitude comparison angle measurement method as described in claim 1, characterized in that, The process of normalized spatial frequency estimation includes: The normalized spatial frequency offset value is determined based on the amplitude ratio table and the relevant information of the detection signal, and the corresponding normalized spatial frequency is calculated from the beam in which the detection signal is located, thereby obtaining the normalized spatial frequency estimate of the radiation source signal.

7. The amplitude comparison angle measurement method as described in claim 1, characterized in that, The process of calculating the two-dimensional incident angle of the signal includes: Based on the intermediate frequency of the detected signal, it is converted into a radio frequency value. Then, using the estimated normalized spatial frequency value and the normalized spatial frequency model, the two-dimensional incident angle of the signal is calculated.

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