Frequency adaptive beam amplitude weighted optimization method for broadband microwave photon system

Abstract

The invention discloses a broadband microwave photon system frequency adaptive beam amplitude weighted optimization method, which comprises the following steps: firstly, connecting different array channels of a microwave photon system by using a detector, and obtaining single-channel antenna array directional diagrams of different channels through testing, thereby constructing a broadband microwave photon system comprehensive antenna directional diagram equation; based on a vector network analyzer, amplitude weighting response conditions of each channel amplitude weighting module under different frequencies are obtained, and a broadband amplitude weighting factor function is constructed; according to a beam pointing demand, beam pointing control is realized through optical true delay, and a current antenna pattern amplitude phase equation of each channel is constructed; and finally, according to the antenna beam width and sidelobe level requirements, adaptively constructing a microwave photon system amplitude weighting optimization model of the key concerned frequency, and solving the microwave photon system amplitude weighting optimization model to obtain the optimal amplitude weighting. According to the scheme, free adjustment of the whole wave beam is realized through actually measuring limited sampling data, wave beam amplitude weighting can be adaptively carried out according to the frequency of a key signal, and the performance of the broadband microwave photon array in different directions is improved.

Description

Technical Field

[0001] The present invention belongs to the field of radar microwave photonics, and in particular relates to a frequency adaptive beam amplitude weighted optimization method for a broadband microwave photonic system. Background Art

[0002] With the continuous development of electronic equipment, the density of electromagnetic signals in space continues to increase, and the spectrum space coverage is becoming more and more complete.

[0003] Unlike traditional RF systems, broadband microwave photonic systems have an extremely large instantaneous bandwidth, so the electromagnetic information they can detect is far greater than that of traditional RF systems. Therefore, during the detection process, it is necessary to enhance the precise tracking of the electromagnetic signals of interest.

[0004] However, the beam amplitude weighting method of the current microwave photonic system is the same as that of the traditional RF system, which can only ensure a high-performance beam that meets the use requirements at a specific direction and characteristic frequency point. It is difficult to fully utilize the ultra-large instantaneous bandwidth characteristics of the microwave photonic system to perform higher-performance detection of specific signals within the detection range.

[0005] Therefore, in order to better achieve high-performance tracking and detection of key signals within the detection range, it is necessary to carry out research on frequency-adaptive beam amplitude weighting technology for broadband microwave photonic systems, so as to improve the array beam performance of broadband microwave photonic systems at specific directions and frequencies. Summary of the Invention

[0006] In response to the above problems, the purpose of the present invention is to provide a frequency-adaptive beam amplitude weighted optimization method for a broadband microwave photonic system. Based on the phase amplitude of the antenna pattern of a single-channel antenna array and the frequency response function of the amplitude weighting module, adaptive beam amplitude weighting is performed on all channels of the broadband microwave photonic system according to the frequency and azimuth of the key signals of interest to the broadband microwave photonic system, thereby adaptively adjusting the microwave photonic system array antenna pattern to ensure high-performance tracking of key signals.

[0007] The specific technical solutions for achieving the purpose of the present invention are as follows:

[0008] A method for frequency-adaptive beam amplitude weighted optimization of a broadband microwave photonic system comprises the following steps:

[0009] Step 1: Use a detector to connect different array channels of the microwave photonic system, and obtain the single-channel antenna array patterns of different channels through testing;

[0010] Step 2: Based on the single-channel antenna array pattern, construct the comprehensive antenna pattern equation of the broadband microwave photonic system;

[0011] Step 3: Using a vector network analyzer, obtain the amplitude weighted response of each channel amplitude weighting module at different frequencies and construct a broadband amplitude weighting factor function;

[0012] Step 4: Based on the beam pointing requirements, beam pointing control is achieved through optical true delay, and the amplitude and phase equations of the antenna pattern of each channel are constructed;

[0013] Step 5: Based on the antenna beam width and sidelobe level requirements, an amplitude weighted optimization model of the microwave photonic system at the key frequencies of interest is adaptively constructed and solved to obtain the optimal amplitude weighting.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The present invention uses the phase amplitude of the antenna pattern of a single-channel antenna array and the frequency response function of the amplitude weighting module as a benchmark. According to the frequency and azimuth of the key signal of interest to the broadband microwave photonic system, all channels of the broadband microwave photonic system are adaptively weighted by beam amplitude, thereby adaptively adjusting the antenna pattern of the microwave photonic system array to ensure high-performance tracking of the key signal.

[0016] (2) The solution of the present invention can realize free adjustment of the entire beam through measured limited sampling data, and can adaptively weight the beam amplitude according to the frequency of the key signal, thereby improving the performance of the broadband microwave photonic array under different pointing directions.

[0017] The present invention will be further described below with reference to specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is a flow chart of the frequency adaptive beam amplitude weighted optimization method for a broadband microwave photonic system of the present invention.

[0019] Figure 2 This is a schematic diagram of a single-channel antenna pattern test according to the present invention.

[0020] Figure 3 Schematic diagram of the frequency domain response test of the amplitude weighting module of the present invention.

[0021] Figure 4 1 is a frequency domain response diagram of the amplitude weighted module with different bit numbers in an embodiment of the present invention.

[0022] Figure 5 This is the antenna pattern without amplitude weighting in the embodiment of the present invention.

[0023] Figure 6 This is the antenna pattern of direct amplitude weighting in the embodiment of the present invention.

[0024] Figure 7This is the antenna pattern after adaptive amplitude weighting in the embodiment of the present invention. DETAILED DESCRIPTION

[0025] Example

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0027] As used in this application and the claims, the words "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural unless the context clearly indicates otherwise. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0028] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0029] Combine Figure 1 , a frequency adaptive beam amplitude weighted optimization method for a broadband microwave photonic system, comprising the following steps:

[0030] Step 1: Use the detector to connect different array channels of the microwave photonic system and obtain the single-channel antenna array patterns of different channels through testing:

[0031] For an N-channel broadband microwave photonic system, the antenna pattern of each channel is tested using a detector;

[0032] Assume that the interval angle during the microwave darkroom test is dθ and the angle sampling is θ p ,θ p=θ0,θ0+dθ,…,θ k , the interval frequency is df, and the frequency sampling is f q , f q =f0,f0+df,…,f k ;

[0033] Then the antenna array pattern function expression of channel i can be obtained as:

[0034]

[0035] like Figure 2 The figure shows a schematic diagram of a single-channel antenna pattern test in this embodiment. The antenna pattern of each channel in the broadband microwave photonic system is tested in a microwave darkroom to obtain antenna pattern functions of different channels.

[0036] Step 2: Based on the single-channel antenna array pattern, construct the comprehensive antenna pattern equation of the broadband microwave photonic system:

[0037]

[0038] Step 3: Using a vector network analyzer, obtain the amplitude weighted response of each channel amplitude weighting module at different frequencies and construct a broadband amplitude weighting factor function:

[0039] The frequency response value of the amplitude weighting module with M bits and N channels in channel i and amplitude weighting bit m is obtained based on the vector network analyzer test: Among them, f a is the sampling value of the vector network analyzer at frequency;

[0040] Set the minimum bit of the amplitude weighted module m min The corresponding amplitude weighted value is dA, then for any amplitude weighted value A d , represented by binary as:

[0041]

[0042] Among them, a m is the corresponding weighted value A d The value of the mth bit of the binary representation value, for example, when A d When the value of is 5, its binary representation is 101, so the corresponding a m 1, 0 and 1 respectively.

[0043] Then for any amplitude weighted bit of channel i, its frequency response is:

[0044]

[0045] like Figure 3As shown in the figure, it is a schematic diagram of the frequency domain response test of the amplitude weighting module in this embodiment, and the following is obtained: Figure 4 The responses of the amplitude weighting module at different frequencies under different control bits are shown.

[0046] Step 4: Based on the beam pointing requirements, beam pointing control is achieved through optical true delay:

[0047]

[0048] Where, Δt i represents the optical delay of channel i, θ s represents the required beam pointing direction, and c represents the speed of light;

[0049] Based on this, the amplitude and phase equations of the antenna patterns of each channel are constructed.

[0050] Step 5: Based on the antenna beamwidth and sidelobe level requirements, adaptively construct an amplitude weighted optimization model for the microwave photonic system at the frequencies of key interest, and solve it to obtain the optimal amplitude weighting:

[0051] Assume the beam points to θ s and the frequency point f c satisfy

[0052] θ p ≤θ s <θ p+1 ,f q ≤f c ≤f q+1

[0053] Then the beam points to θ s and the frequency point f c The amplitude and phase of the i-channel antenna pattern under can be expressed as:

[0054]

[0055] Assume the frequency point f c satisfy:

[0056] f a ≤f c <f a+1

[0057] Then the frequency response of the amplitude weighting module of channel i with amplitude weighting position m is It can be expressed as:

[0058]

[0059] Then for the amplitude weighted value A d , its frequency response can be expressed as

[0060]

[0061] Assume that the amplitude weighted value of channel i is Then the antenna pattern of channel i in the current case can be expressed as:

[0062]

[0063] Then the antenna pattern of the entire microwave photonic system can be expressed as:

[0064]

[0065] According to the beam width θ 0d and sidelobe level requirements SLL min , construct the optimization equation:

[0066] θ d [F(θ s ,f c )]<θ d0 ,SLL[F(θ s ,f c )]<SLL min

[0067] The initial amplitude weighting coefficient is constructed using the optimal array factor Chebyshev array factor or Taylor array factor under ideal conditions: Then assume that the amplitude weighted bits between channels i cannot exceed C i , then the coefficients obtained by the nth Monte Carlo method are:

[0068]

[0069] Then, the optimal amplitude weighting coefficient, that is, the optimal amplitude weighting value, is searched out through traversal, thereby determining the optimal weighting position of the amplitude weighting module and completing the optimization.

[0070] like Figure 5 As shown in the figure, the sidelobe level of a 32-channel system with no beam amplitude weighting and a beam pointing at -10° is about -12dB, which is difficult to meet the actual needs.

[0071] like Figure 6 As shown in the figure, similar to the traditional method, each channel is amplitude-weighted based on the amplitude and phase characteristics of the RF module of each channel. This can ensure that the sidelobe level at the center frequency of 12 GHz is below -23 dB, while the sidelobe level at 16 GHz is around -19 dB.

[0072] Based on the antenna pattern after adaptive amplitude weighting in this scheme, Figure 7As shown, assuming that the electromagnetic signal of interest is at the -10° position and the frequency is 16 GHz, the adaptive beam amplitude weighting method described in the present invention can accurately reduce the sidelobe level at 16 GHz to below -23 dB, which can improve the performance of broadband microwave photonic arrays in different pointing directions.

[0073] The present invention also provides a broadband microwave photonic system frequency adaptive beam amplitude weighted optimization system, comprising the following modules:

[0074] Test module: Use detectors to connect different array channels of the microwave photonic system and obtain the single-channel antenna array patterns of different channels through testing;

[0075] Comprehensive antenna pattern construction module: used to construct the comprehensive antenna pattern equation of the broadband microwave photonic system based on the single-channel antenna array pattern;

[0076] Channel amplitude weighting test module: used to obtain the amplitude weighted response of each channel amplitude weighting module at different frequencies based on a vector network analyzer, and to construct a broadband amplitude weighting factor function;

[0077] Beam pointing control module: used to implement beam pointing control through optical true delay according to beam pointing requirements and construct the amplitude and phase equations of the antenna pattern of each channel;

[0078] Optimization module: It is used to adaptively construct an amplitude-weighted optimization model of the microwave photonic system at the frequencies of key concern based on the antenna beam width and sidelobe level requirements, and solve it to obtain the optimal amplitude weighting.

[0079] The present invention further provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the following steps are implemented:

[0080] Step 1: Use a detector to connect different array channels of the microwave photonic system, and obtain the single-channel antenna array patterns of different channels through testing;

[0081] Step 2: Based on the single-channel antenna array pattern, construct the comprehensive antenna pattern equation of the broadband microwave photonic system;

[0082] Step 3: Using a vector network analyzer, obtain the amplitude weighted response of each channel amplitude weighting module at different frequencies and construct a broadband amplitude weighting factor function;

[0083] Step 4: Based on the beam pointing requirements, beam pointing control is achieved through optical true delay, and the amplitude and phase equations of the antenna pattern of each channel are constructed;

[0084] Step 5: Based on the antenna beam width and sidelobe level requirements, an amplitude weighted optimization model of the microwave photonic system at the key frequencies of interest is adaptively constructed and solved to obtain the optimal amplitude weighting.

[0085] The present invention further provides a computer storable medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the following steps are implemented:

[0086] Step 1: Use a detector to connect different array channels of the microwave photonic system, and obtain the single-channel antenna array patterns of different channels through testing;

[0087] Step 2: Based on the single-channel antenna array pattern, construct the comprehensive antenna pattern equation of the broadband microwave photonic system;

[0088] Step 3: Using a vector network analyzer, obtain the amplitude weighted response of each channel amplitude weighting module at different frequencies and construct a broadband amplitude weighting factor function;

[0089] Step 4: Based on the beam pointing requirements, beam pointing control is achieved through optical true delay, and the amplitude and phase equations of the antenna pattern of each channel are constructed;

[0090] Step 5: Based on the antenna beam width and sidelobe level requirements, an amplitude weighted optimization model of the microwave photonic system at the key frequencies of interest is adaptively constructed and solved to obtain the optimal amplitude weighting.

[0091] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A frequency-adaptive beam amplitude weighted optimization method for a broadband microwave photonic system, characterized in that: The following steps are involved: Step 1: Use a detector to connect different array channels of the microwave photonic system, and obtain the single-channel antenna array patterns of different channels through testing; Step 2: Based on the single-channel antenna array pattern, construct the comprehensive antenna pattern equation of the broadband microwave photonic system; Step 3: Using a vector network analyzer, obtain the amplitude weighted response of each channel amplitude weighting module at different frequencies and construct a broadband amplitude weighting factor function; Step 4: Based on the beam pointing requirements, beam pointing control is achieved through optical true delay, and the amplitude and phase equations of the antenna pattern of each channel are constructed; Step 5: Based on the antenna beam width and sidelobe level requirements, an amplitude weighted optimization model of the microwave photonic system at the key frequencies of interest is adaptively constructed and solved to obtain the optimal amplitude weighting.

2. The frequency adaptive beam amplitude weighting method for a broadband microwave photonic system according to claim 1, characterized in that: The step 1 of obtaining the single-channel antenna array pattern of different channels is specifically as follows: For an N-channel broadband microwave photonic system, the antenna pattern of each channel is tested using a detector; Assume that the interval angle during the microwave darkroom test is dθ and the angle sampling is θ p ,θ p =θ0,θ0+dθ,…,θ k , the interval frequency is df, and the frequency sampling is f q , f q =f0,f0+df,…,f k ; Then the antenna array pattern function expression of channel i can be obtained as:

3. The frequency adaptive beam amplitude weighting method for a broadband microwave photonic system according to claim 2, characterized in that: The broadband microwave photonic system integrated antenna pattern equation in step 2 is:

4. The frequency adaptive beam amplitude weighting method for a broadband microwave photonic system according to claim 2, characterized in that: The broadband amplitude weighting factor function in step 3 is specifically: The frequency response value of the amplitude weighting module with M bits and N channels in channel i and amplitude weighting bit m is obtained based on the vector network analyzer test: Among them, f a is the sampling value of the vector network analyzer at frequency; Set the minimum bit of the amplitude weighted module m min The corresponding amplitude weighted value is dA, then for any amplitude weighted value A d , represented by binary as: Among them, a m is the corresponding weighted value A d The value of the mth bit of the binary representation value of ; Then for any amplitude weighted bit of channel i, its frequency response is:

5. The frequency adaptive beam amplitude weighting method for a broadband microwave photonic system according to claim 1, characterized in that: The beam pointing control is achieved by optical true delay in step 4: Where, Δt i represents the optical delay of channel i, θ s represents the required beam pointing direction, and c represents the speed of light.

6. The frequency adaptive beam amplitude weighting method for a broadband microwave photonic system according to claim 4, characterized in that: The step 5 of obtaining the optimal amplitude weighting is specifically as follows: According to the beam width θ 0d and sidelobe level requirements SLL min , construct an amplitude-weighted optimization model for microwave photonic systems with a focus on frequency: θ d [F(θ s ,f c )]<θ d0 ,SLL[F(θ s ,f c )]<SLL min Among them, θ s represents the required beam pointing, f c Indicates the frequency point of focus, F(θ s ,f c ) represents the antenna pattern of the microwave photonic system under this condition, represents the initial amplitude weighting coefficient under ideal conditions, C i represents the amplitude weighted bit threshold between channels i, F i (θ s ,f c ), They represent the beam pointing direction θ s and the frequency point f c The amplitude and phase of the antenna pattern of channel i under ; The constructed amplitude weighted optimization model is traversed to obtain the optimal amplitude weighting coefficient, that is, the optimal amplitude weighting value, so as to determine the optimal weighting position of the amplitude weighting module and complete the optimization.

7. A frequency-adaptive beam amplitude weighted optimization system for a broadband microwave photonic system, characterized in that: Includes the following modules: Test module: Use detectors to connect different array channels of the microwave photonic system and obtain the single-channel antenna array patterns of different channels through testing; Comprehensive antenna pattern construction module: used to construct the comprehensive antenna pattern equation of the broadband microwave photonic system based on the single-channel antenna array pattern; Channel amplitude weighting test module: used to obtain the amplitude weighted response of each channel amplitude weighting module at different frequencies based on a vector network analyzer, and to construct a broadband amplitude weighting factor function; Beam pointing control module: used to implement beam pointing control through optical true delay according to beam pointing requirements and construct the amplitude and phase equations of the antenna pattern of each channel; Optimization module: It is used to adaptively construct an amplitude-weighted optimization model of the microwave photonic system at the frequencies of key concern based on the antenna beam width and sidelobe level requirements, and solve it to obtain the optimal amplitude weighting.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer storable medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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