Radar radio frequency stealth method and system using spatial low intercept design

Abstract

The present application belongs to the field of radar technology, and relates to a radar radio frequency stealth method and system for low-interception design in space domain beam. The method comprises the following steps: constructing an encoding matrix of array element-pulse domain and a radar ambiguity function; configuring radar array parameters, setting a target direction of radar detection; calculating a basic scanning phase; constructing an expression of a basic low-gain directional diagram; generating a plurality of groups of low-gain directional diagrams of scanning directions; weighting and summing to obtain an expression of a target function of a high-gain directional diagram; and solving a weighting coefficient to obtain an expression of a synthesized high-gain directional diagram. The present application greatly reduces the interception probability of a high-gain beam by an enemy passive reconnaissance while ensuring the detection performance; the spatial distribution of a low-gain beam is naturally adapted to the high-gain synthesis requirement, a mathematical model of a high-gain detection beam and a weight value solving method are constructed through linear combination, the transmission with controllable low-interception risk is realized, and the performance balance of equivalent high-gain detection is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of radar, and in particular, relates to a radar radio frequency stealth method and system for a space domain low-interception design. BACKGROUND

[0002] With the development of electronic countermeasure technology, the survival of radar is facing severe challenges: the radar without radio frequency stealth capability is easy to be intercepted by passive devices such as anti-radiation missiles, radar warning receivers and electronic intelligence systems, therefore, the radio frequency stealth technology can reduce the probability of signal interception while ensuring the radar detection performance.

[0003] In order to counter the increasingly superior passive reconnaissance system, reduce the risk of interception, attack and even destruction of the own side, it is necessary to improve the survival ability of the radar, and it is urgent to develop radar radio frequency stealth technology with high resolution performance and strong anti-interception capability, and the radar waveform as the carrier of the direct confrontation between radar and reconnaissance and jamming is particularly important and more valuable for realizing the balanced waveform design of radar target detection and radio frequency stealth.

[0004] The LPI radar (Low Probability of Intercept Radar) needs to make its maximum detection distance greater than the distance of the enemy interception receiver, the mainstream LFM (Linear Frequency Modulation) - frequency code composite signal increases the difficulty of interception by complex modulation, but there is a problem of high distance sidelobe; the FDA (Frequency Diverse Array) realizes a certain low interception by time-varying pattern, but it is difficult to complete the target coherent accumulation, and the detection capability is weak.

[0005] The MIMO radar (Multiple-Input Multiple-Output Radar) disperses the transmitted energy through orthogonal waveforms, and the low interception is only a by-product, the core is to break through the beam pre-focusing limit of phased array, and the transmit pattern is dispersed without purpose, which is only suitable for low confrontation scenes such as civil remote sensing, and in a strong electronic countermeasure environment, the low interception performance is poor and the coherent accumulation capability is weaker than that of the phased array radar. SUMMARY

[0006] In order to solve the above technical problems, the present application provides a radar radio frequency stealth method and system for a space domain low-interception design.

[0007] In a first aspect, the present application provides a radar radio frequency stealth method for a space domain low-interception design, comprising:

[0008] The weight vector of the array element dimension and the pulse dimension is configured, the encoding matrix of the array element-pulse domain and the radar ambiguity function are constructed, the average side lobe level of the radar ambiguity function is minimized, and the side lobe level is reduced to be less than a set threshold while keeping the main lobe level of the detection angle and the Doppler unit not less than a set threshold;

[0009] The radar array parameters are configured, and the target direction of radar detection is set; the radar array parameters include the number of array elements, the array element spacing and the wavelength;

[0010] The basic scanning phase is calculated, and the expression of the basic low-gain pattern is constructed according to the basic scanning phase;

[0011] The low-gain patterns of a plurality of groups of scanning directions are generated according to the basic low-gain pattern;

[0012] The low-gain patterns of all scanning directions are weighted and summed to obtain the expression of the target function of the high-gain pattern;

[0013] The weighted coefficients are solved to obtain the expression of the synthesized high-gain pattern;

[0014] The transmitting array transmits a pseudo-random low-gain beam associated with the target direction based on the encoding matrix of the array element-pulse domain and the weighted coefficients, the receiving array receives the UAV navigation echo and outputs an echo vector, the echo vector is matched filtered, the high-gain interference beam is synthesized combined with the weighted coefficients and output to the UAV navigation frequency band.

[0015] In a second aspect, the present application provides a radar radio frequency stealth system adopting a spatial domain low-interception design, including a first construction unit, a configuration unit, a second construction unit, a generation unit, a third construction unit, a solving unit and an output unit;

[0016] The first construction unit is configured to configure the weight vector of the array element dimension and the pulse dimension, construct the encoding matrix of the array element-pulse domain and the radar ambiguity function, minimize the average side lobe level of the radar ambiguity function, and reduce the side lobe level to be less than a set threshold while keeping the main lobe level of the detection angle and the Doppler unit not less than a set threshold;

[0017] The configuration unit is configured to configure the radar array parameters and set the target direction of radar detection; the radar array parameters include the number of array elements, the array element spacing and the wavelength;

[0018] The second construction unit is configured to calculate the basic scanning phase and construct the expression of the basic low-gain pattern according to the basic scanning phase;

[0019] The generation unit is configured to generate a plurality of groups of low-gain patterns of scanning directions according to the basic low-gain pattern;

[0020] The third building block is used to perform a weighted summation of the low-gain radiation patterns in all scanning directions to obtain the expression for the objective function of the high-gain radiation pattern.

[0021] The solving element is used to solve for the weighting coefficients to obtain the expression for the synthesized high-gain radiation pattern;

[0022] The output unit is used to transmit a pseudo-random low-gain beam correlated with the target direction based on the element-pulse domain coding matrix and weighting coefficients of the transmitting array. The receiving array receives the UAV navigation echo and outputs the echo vector. The echo vector is subjected to matched filtering, and combined with the weighting coefficients to synthesize a high-gain interference beam and output it to the UAV navigation frequency band. Based on the above technical solution, the present invention can also be improved as follows.

[0023] Furthermore, configure the radar array parameters and calculate the basic scanning phase, including setting the number of array elements to be... The basic scanning phase is The basic scan phase is then expressed as: .

[0024] Furthermore, an expression for constructing the basic low-gain pattern based on the basic scanning phase and coding matrix is ​​provided, including: assuming the wavelength is... The spacing between array elements is The number of array elements is , It is a constant. As an auxiliary variable, The auxiliary variable is represented as: , This is the radiation pattern of the array. Since the integer is imaginary, the array radiation pattern is represented as:

[0025] ;

[0026] set up If we consider the basic low-gain radiation pattern, then the basic low-gain radiation pattern is represented as:

[0027] .

[0028] Furthermore, based on the basic low-gain pattern, several sets of low-gain patterns for scanning directions are generated, including:

[0029] set up For the first The weighting factors for the design of each antenna. for The maximum value, The value is an imaginary number, and the spacing between array elements is... , It is a constant. As an auxiliary variable, , the number of array elements is , the basic scanning phase is , , is the low-gain pattern of the first group of scanning directions;

[0030] The basic low-gain pattern scans different directions to obtain the low-gain pattern of the first group of scanning directions, denoted as:

[0031] ;

[0032] The low-gain pattern of the first group of scanning directions is denoted as:

[0033] .

[0034] Further, the low-gain patterns of all scanning directions are weighted and summed to obtain the expression of the objective function of the high-gain pattern, including:

[0035] Let be the weighting coefficient of the low-gain pattern, be the beam number, be the array element number, and the number of array elements is , be the auxiliary variable, and the array element spacing is , be a constant, , be the high-gain pattern, be the low-gain pattern of the first group of scanning directions, and the expression of the objective function of the high-gain pattern is:

[0036] .

[0037] The beneficial effects of the present application are:

[0038] (1) The present application is based on the synthesis of low-gain beams in different directions to obtain high-gain beams, which breaks through the traditional random dispersion logic of MIMO transmit beams. By designing the phase and direction of the basic low-gain beam to be highly related to the target direction, the spatial distribution of the low-gain beam naturally adapts to the high-gain synthesis requirement, making the seemingly random variation of the low-gain transmission actually a pre-preparation for the accurate aggregation of target echoes at the receiving end. While ensuring the detection performance, the probability of interception of high-gain beams by enemy passive reconnaissance is greatly reduced;

[0039] (2) The linear synthesis and weight solving method of high-low gain beam is adopted, the mathematical model and weight solving method of constructing high gain detection beam by linear combination are proposed based on low gain basic pattern, the linear superposition relationship between high gain pattern and low gain set is established by defining basic pattern and generating scanning set, the weight calculation method based on matrix inversion is derived, the controllable low interception risk transmission is realized, the performance balance of equivalent high gain detection is achieved, and a new technical path is provided for the cooperative design of radar RF stealth and target detection. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A radar RF stealth method for a spatial low interception design is provided for embodiment 1 of the present application.

[0041] Figure 2 A schematic diagram of the weight vector of the array element and pulse dimension is shown.

[0042] Figure 3 A comparison diagram of the basic low gain pattern and the high gain pattern is shown.

[0043] Figure 4 Gain beams in different directions synthesized when the antenna scanning angle is 0°.

[0044] Figure 5 Gain beams in different directions synthesized when the antenna scanning angle is -30°.

[0045] Figure 6 Gain beams in different directions synthesized when the antenna scanning angle is 30°.

[0046] Figure 7 A radar RF stealth system for a spatial low interception design is provided for embodiment 2 of the present application. DETAILED DESCRIPTION

[0047] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Embodiment 1

[0049] As an embodiment, as shown in the accompanying drawings, to solve the above technical problems, the present embodiment provides a radar RF stealth method for a spatial low interception design, which comprises: Figure 1

[0050] ​The weight vector of the array element dimension and the pulse dimension is configured, the encoding matrix of the array element-pulse domain and the radar ambiguity function are constructed, so that the average side lobe level of the radar ambiguity function is minimized, and the side lobe level is reduced to less than a set threshold, while the main lobe level of the detection angle and the Doppler unit is kept not lower than a set threshold;

[0051] The radar array parameters are configured, and the target direction of the radar detection is set; the radar array parameters include the number of array elements, the array element spacing and the wavelength;

[0052] The basic scanning phase is calculated, and the expression of the basic low-gain pattern is constructed according to the basic scanning phase;

[0053] The low-gain patterns of a plurality of groups of scanning directions are generated according to the basic low-gain pattern;

[0054] The low-gain patterns of all scanning directions are weighted and summed to obtain the expression of the target function of the high-gain pattern;

[0055] The weighted coefficients are solved to obtain the expression of the synthesized high-gain pattern;

[0056] The transmitting array transmits a pseudo-random low-gain beam associated with the target direction based on the encoding matrix of the array element-pulse domain and the weighted coefficients, the receiving array receives the UAV navigation echo and outputs an echo vector, the echo vector is matched filtered, the high-gain interference beam is synthesized combined with the weighted coefficients and output to the UAV navigation frequency band. The design principle of the present application is: for the airspace with high interception risk, the radiation power of the pattern is as low as possible; the excess energy is radiated to the relatively safe low-risk airspace; for other unknown airspace, the radiation power is as low as possible. The main optimization parameters are the weight vector of the array element dimension and the pulse dimension, as shown in the attached Figure 2 figure, the horizontal axis is the pulse, and the vertical axis is the array element, represents the number of transmitting array elements, represents the number of pulses transmitted in a CPI (Coherent Processing Interval), is the pulse repetition period, represents that the pulse is the number of transmitting array elements and the array element is the weight vector.

[0057] Optionally, let be a linear frequency modulation signal, be a carrier frequency, be a linear frequency modulation signal bandwidth, be a frequency modulation signal duration, be a pulse transmission interval, when it is a continuous wave signal, is less than , , is the code word transmitted by the th antenna, and the target direction is , , denotes the number of pulses transmitted within a CPI, then the linear frequency modulation signal is

[0058] ;

[0059] The signal of the th transmitting antenna is denoted as

[0060] ;

[0061] Let the transmitting array be a linear array with elements, and the receiving array be a linear array with elements. Let be the transmitting steering vector corresponding to the target direction , and be the receiving steering vector corresponding to the direction , denote the position of the transmitting element as , and the position of the receiving element as , and the wavelength as ;

[0062] ;

[0063] ;

[0064] Let denote the encoding matrix in the element-pulse domain, with the dimension of , then the encoding matrix in the element-pulse domain is denoted as

[0065] .

[0066] Optionally, for a point target, let the Doppler frequency be , be the starting frequency of the radar signal sweep, be the frequency modulation slope of the linear frequency modulation, denote the transmitting steering vector, denote the receiving steering vector, denote the conjugate transpose, and define the diagonal matrix , denote the number of pulses transmitted within a CPI, be the number of antennas, denote the diagonal matrix;

[0067] ;

[0068] Let the target direction be , the target distance be , the Doppler frequency be , and the ambiguity function be , then the ambiguity function is expressed as:

[0069] ;

[0070] Let represent column vectorization, represent the Kronecker product, be a target reflection echo and a reference transmission signal matched filtering output vector, be a signal receiving vector spliced from receiving elements pulses, and be expressed as: ;

[0071] Let be a sampling interval, be the number of sampling points in each frequency modulation signal period, be the speed of light, be a transposed matrix, be an imaginary number, the target distance be , be a frequency modulation slope of the linear frequency modulation, then: ; then: ;

[0072] The dimension of the matrix is , and contains echoes of pulses of an antenna, and is expressed as:

[0073] ;

[0074] Let be the dimension of the matrix containing echoes of pulses of an antenna, and be expressed as: , the ambiguity function is expressed as a function of the distance difference, then:

[0075] ;

[0076] .

[0077] Optionally, let represent a high-risk area that may exist in the receiver, and if no information is available, set to an empty set, to a general area, A safe region for intelligence gathering, A target direction;

[0078] Let be the main lobe peak point of the ambiguity function, denote the i-th column of the encoding matrix, denote the i-th pulse, denote a low intercept performance variable of a high risk region, denote a mean side lobe reduction performance function, denote the main lobe peak point of the ambiguity function, denote a radar target detection performance variable, denote a transmit steering vector, denote the i-th column of the encoding matrix, be a constant, be a constant;

[0079] A weight vector of the array dimension and the pulse dimension is configured, an encoding matrix of the array-pulse domain is constructed, so that the mean side lobe level of the radar ambiguity function is minimized, and the side lobe level is reduced to less than a set threshold, while keeping the main lobe level of the detection angle and the Doppler unit not lower than a set threshold, and is expressed as:

[0080] ;

[0081] .

[0082] A high-gain phased array beam is easily intercepted, and the high-gain beam can be generated by a series of low-gain beams. A high-gain phased array beam is replaced by a series of low-gain beams with constantly changing directions, and processing is performed to maintain consistent performance with the high-gain beam, thereby improving the low-intercept characteristics of the radar.

[0083] Suppose an element linear array, let be a constant, be the array element spacing, be the target direction, and the far-field radiation pattern is:

[0084] .

[0085] Optionally, the radar array parameters are configured, and the basic scanning phase is calculated, including: let the number of array elements be , and the basic scanning phase be , then the basic scanning phase is expressed as: .

[0086] ​​Optionally, an expression for constructing the basic low-gain pattern based on the basic scanning phase and the coding matrix is ​​included, including: assuming the wavelength is... The spacing between array elements is The number of array elements is , It is a constant. As an auxiliary variable, The auxiliary variable is represented as: , This is the radiation pattern of the array. Since the integer is imaginary, the array radiation pattern is represented as:

[0087] ;

[0088] High-gain radiation patterns can be achieved by controlling the modulation phase of array elements, and thus high-gain radiation patterns can be synthesized from a series of low-gain basic radiation patterns.

[0089] ;

[0090] ;

[0091] ;

[0092] Until the Basic scan direction map:

[0093] ;

[0094] If a high-gain scanning pattern can be obtained by linearly combining a series of low-gain base patterns, then the goal of low interception can be achieved.

[0095] set up If we consider the basic low-gain radiation pattern, then the basic low-gain radiation pattern is represented as:

[0096] .

[0097] The above radiation pattern can be minimized by a set of optimized codes, as shown in the appendix. Figure 3 The diagram shows a comparison between the basic low-gain and high-gain radiation patterns. L1 represents the high-gain pattern, and L2 represents the basic low-gain pattern.

[0098] Optionally, several sets of low-gain radiation patterns for scanning directions are generated based on the basic low-gain radiation pattern, including:

[0099] set up For the first The weighting factors for the design of each antenna. for The maximum value, The value is an imaginary number, and the spacing between array elements is... , It is a constant. As an auxiliary variable, The number of array elements is The basic scan phase is , , For the first Low-gain pattern in the group scan direction;

[0100] The basic low-gain pattern is scanned in different directions to obtain the low-gain pattern of the first set of scan directions, which is represented as:

[0101] ;

[0102] No. The low-gain pattern of the group scan direction is represented as follows:

[0103] .

[0104] This set of directional patterns can be seen as The results obtained from scanning in different directions are all low gain.

[0105] Optionally, a weighted summation of the low-gain radiation patterns across all scanning directions is performed to obtain an expression for the objective function of the high-gain radiation pattern, including:

[0106] set up These are the weighting coefficients for the low-gain radiation pattern. Number the beams. The array elements are numbered, and the number of array elements is . , As an auxiliary variable, the element spacing is , It is a constant. , This is a high-gain radiation pattern. For the first The objective function expressions for the low-gain and high-gain radiation patterns in the group scan direction are:

[0107] Other high-gain beams can be expressed similarly. If the weighting coefficients are used, then the following can be obtained. , until , It can be represented as:

[0108] .

[0109] Optionally, the weighting coefficients can be solved by inverting the inverse matrix, including: setting the number of matrix elements to be... , is an auxiliary variable, and the array element spacing is , is a constant, , the basic scanning phase is , is a high-gain pattern, is a basic low-gain pattern, and the beam weighting coefficient vector is , is the inverse matrix of the weighting coefficient, and the inverse matrix of the weighting coefficient multiplied by the beam weighting coefficient vector obtains a full one vector, and the expression of the high-gain pattern is expanded to obtain a linear equation group:

[0110] ;

[0111] ;

[0112] The weighting coefficient is expressed as:

[0113] .

[0114] A cluster of low-gain basic beams synthesized in different directions is realized, and high-gain beams in different directions are synthesized, as shown in the accompanying drawings Figure 4 - the horizontal axis is the antenna scanning angle, the unit is °, and the vertical axis is the gain, the unit is dB, and the accompanying drawings Figure 6 is the synthesized gain beam in different directions when the antenna scanning angle is 0°, L3 is the synthesized high-gain beam, L4 is the basic low-gain beam set, and the accompanying drawings Figure 4 is the synthesized gain beam in different directions when the antenna scanning angle is -30°, L5 is the synthesized high-gain beam, and the accompanying drawings Figure 5 is the synthesized gain beam in different directions when the antenna scanning angle is 30°, and L6 is the synthesized high-gain beam. Figure 6

[0115] The application is based on the synthesis of low-gain beams in different directions to break through the random dispersion logic of the traditional MIMO transmitting beam, and through the design of the phase and direction of the basic low-gain beam highly related to the target direction, the spatial distribution of the low-gain beam is naturally adapted to the high-gain synthesis requirement, and the seemingly random change of the low-gain transmission is actually a pre-preparation for the accurate aggregation of the target echo at the receiving end, which greatly reduces the interception probability of the high-gain beam by the enemy passive reconnaissance while ensuring the detection performance.

[0116] ​This invention employs a linear synthesis and weighting method for high- and low-gain beams. It proposes a mathematical model and weighting method for constructing high-gain detection beams using a low-gain base pattern as a unit through linear combination. By defining the base pattern and generating a scanning set, a linear superposition relationship between the high-gain pattern and the low-gain set is established. A weighting calculation method based on matrix inversion is derived, enabling controllable transmission with low interception risk and achieving a performance balance of equivalent high-gain detection. This provides a novel technical path for the collaborative design of radar radio frequency stealth and target detection.

[0117] Example 2

[0118] Based on the same principle as the method shown in Embodiment 1 of the present invention, as illustrated in the appendix. Figure 7 As shown, embodiments of the present invention also provide a radar radio frequency stealth system with low intercept design in the airspace, including a first construction unit, a configuration unit, a second construction unit, a generation unit, a third construction unit, a solution unit, and an output unit;

[0119] The first construction unit is used to configure the weight vectors of the array element dimension and the pulse dimension, construct the encoding matrix and radar ambiguity function of the array element-pulse domain, so that the average sidelobe level of the radar ambiguity function is minimized and the sidelobe level is reduced to less than a set threshold, while keeping the detection angle and the main lobe level of the Doppler unit not lower than a set threshold.

[0120] The configuration unit is used to configure radar array parameters and set the target direction for radar detection; radar array parameters include the number of array elements, the element spacing, and the wavelength.

[0121] The second construction unit is used to calculate the basic scanning phase and construct an expression for the basic low-gain pattern based on the basic scanning phase.

[0122] The generation unit is used to generate several sets of low-gain radiation patterns for scanning directions based on the basic low-gain radiation pattern.

[0123] The third building block is used to perform a weighted summation of the low-gain radiation patterns in all scanning directions to obtain the expression for the objective function of the high-gain radiation pattern.

[0124] The solving element is used to solve for the weighting coefficients to obtain the expression for the synthesized high-gain radiation pattern;

[0125] The output unit is used to transmit pseudo-random low-gain beams associated with the target direction based on the encoding matrix and weighting coefficients of the array element-pulse domain. The receiving array receives the UAV navigation echo and outputs the echo vector. The echo vector is matched and filtered, and combined with the weighting coefficients to synthesize a high-gain interference beam and output it to the UAV navigation frequency band.

[0126] Optionally, the radar array parameter is configured, and the basic scanning phase is calculated, including: setting the number of array elements as , and the basic scanning phase as , the basic scanning phase is represented as: .

[0127] Optionally, the expression of the basic low-gain pattern is constructed according to the basic scanning phase and the coding matrix, including: setting the wavelength as , the array element spacing as , and the number of array elements as , is a constant, is an auxiliary variable, , the auxiliary variable is represented as: , is the array radiation pattern, is an imaginary number, and the array radiation pattern is represented as:

[0128] ;

[0129] Setting as the basic low-gain pattern, the basic low-gain pattern is represented as:

[0130] .

[0131] Optionally, a plurality of sets of scanning direction low-gain patterns are generated according to the basic low-gain pattern, including:

[0132] Setting as the designed weighting coefficient of the i-th antenna, as the maximum value of , is an imaginary number, and the array element spacing is , is a constant, is an auxiliary variable, , the number of array elements is , the basic scanning phase is , , , is the low-gain pattern of the i-th scanning direction; The basic low-gain pattern scans different directions to obtain the low-gain pattern of the first set of scanning directions, which is represented as:

[0133]

[0134] ; The low-gain pattern of the i-th set of scanning directions is represented as:

[0135]

[0136] ​​ .

[0137] Optionally, a weighted summation of the low-gain radiation patterns across all scanning directions is performed to obtain an expression for the objective function of the high-gain radiation pattern, including:

[0138] set up These are the weighting coefficients for the low-gain radiation pattern. Number the beams. The array elements are numbered, and the number of array elements is . , As an auxiliary variable, the element spacing is , It is a constant. , This is a high-gain radiation pattern. For the first The objective function expressions for the low-gain and high-gain radiation patterns in the group scan direction are:

[0139] .

[0140] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A radar radio frequency stealth method employing a low-intercept design in the airspace, characterized in that, include: Configure the weight vectors of the array element dimension and the pulse dimension, construct the encoding matrix and radar ambiguity function of the array element-pulse domain, so that the average sidelobe level of the radar ambiguity function is minimized and the sidelobe level is reduced to less than the set threshold, while keeping the detection angle and the main lobe level of the Doppler unit not lower than the set threshold. Configure radar array parameters and set the target direction for radar detection; radar array parameters include the number of array elements, the element spacing, and the wavelength. Calculate the basic scanning phase, and construct an expression for the basic low-gain pattern based on the basic scanning phase; Several sets of low-gain radiation patterns for scanning directions are generated based on the basic low-gain radiation pattern. The expression for the objective function of the high-gain pattern is obtained by weighted summation of the low-gain patterns in all scanning directions. Solving for the weighting coefficients yields the expression for the synthesized high-gain radiation pattern; The transmitting array transmits a pseudo-random low-gain beam associated with the target direction based on the element-pulse domain coding matrix and weighting coefficients. The receiving array receives the UAV navigation echo and outputs the echo vector. The echo vector is matched and filtered, and combined with the weighting coefficients to synthesize a high-gain interference beam and output to the UAV navigation frequency band.

2. The radar radio frequency stealth method for employing a low-intercept design in the airspace, as described in claim 1, is characterized in that... Configure radar array parameters and calculate the basic scanning phase, including setting the number of array elements as follows: The basic scanning phase is The basic scan phase is then expressed as: .

3. The radar radio frequency stealth method for employing a low-intercept design in the airspace, as described in claim 1, is characterized in that... The expression for constructing the basic low-gain pattern based on the basic scanning phase and coding matrix includes: assuming the wavelength is... The spacing between array elements is The number of array elements is , It is a constant. As an auxiliary variable, The auxiliary variable is represented as: , This is the radiation pattern of the array. Since the integer is imaginary, the array radiation pattern is represented as: ； set up If we consider the basic low-gain radiation pattern, then the basic low-gain radiation pattern is represented as: 。 4. The radar radio frequency stealth method for employing a low-intercept design in the airspace, as described in claim 1, is characterized in that... Several sets of low-gain radiation patterns for scanning directions are generated based on the basic low-gain radiation pattern, including: set up For the first The weighting factors for the design of each antenna. for The maximum value, The value is an imaginary number, and the spacing between array elements is... , It is a constant. As an auxiliary variable, The number of array elements is The basic scanning phase is , , For the first Low-gain pattern in the group scan direction; The basic low-gain pattern is scanned in different directions to obtain the low-gain pattern of the first set of scan directions, which is represented as: ； No. The low-gain pattern of the group scan direction is represented as follows: 。 5. The radar radio frequency stealth method for employing a low-intercept design in the airspace, as described in claim 1, is characterized in that... The low-gain radiation patterns of all scanning directions are weighted and summed to obtain the expression for the objective function of the high-gain radiation pattern, including: set up These are the weighting coefficients for the low-gain radiation pattern. Number the beams. The array elements are numbered, and the number of array elements is . , As an auxiliary variable, the element spacing is , It is a constant. , This is a high-gain radiation pattern. For the first The objective function expressions for the low-gain and high-gain radiation patterns in the group scan direction are: 。 6. A radar radio frequency stealth system employing a low-intercept design in the airspace, characterized in that, It includes a first construction unit, a placement unit, a second construction unit, a generation unit, a third construction unit, a solution unit, and an output unit; The first construction unit is used to configure the weight vectors of the array element dimension and the pulse dimension, construct the encoding matrix and radar ambiguity function of the array element-pulse domain, so that the average sidelobe level of the radar ambiguity function is minimized and the sidelobe level is reduced to less than a set threshold, while keeping the detection angle and the main lobe level of the Doppler unit not lower than a set threshold. The configuration unit is used to configure radar array parameters and set the target direction for radar detection. Radar array parameters include the number of array elements, the spacing between array elements, and the wavelength; The second construction unit is used to calculate the basic scanning phase and construct an expression for the basic low-gain pattern based on the basic scanning phase. The generation unit is used to generate several sets of low-gain radiation patterns for scanning directions based on the basic low-gain radiation pattern. The third building block is used to perform a weighted summation of the low-gain radiation patterns in all scanning directions to obtain the expression for the objective function of the high-gain radiation pattern. The solving element is used to solve for the weighting coefficients to obtain the expression for the synthesized high-gain radiation pattern; The output unit is used to transmit pseudo-random low-gain beams associated with the target direction based on the encoding matrix and weighting coefficients of the array element-pulse domain. The receiving array receives the UAV navigation echo and outputs the echo vector. The echo vector is matched and filtered, and combined with the weighting coefficients to synthesize a high-gain interference beam and output it to the UAV navigation frequency band.

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