Sar complex phase modulation jamming method based on phase-adjustable metasurface

Abstract

The application discloses a SAR composite phase modulation jamming method based on a phase-adjustable metasurface, and relates to the technical field of signal processing.The phase-adjustable metasurface designed by the application adopts a multi-layer metal base and a design of a butterfly-shaped structure unit, so that the whole structure is compact and easy to be integrated into the surface of a protected target, and a varactor diode is introduced as a control element; by changing the voltage applied to the two sides of the first butterfly-shaped structure unit and the second butterfly-shaped structure unit, the equivalent capacitance of the varactor diode can be controlled in real time, and then the continuous change control of the phase of the incident electromagnetic wave is realized; by only designing the first butterfly-shaped structure unit and the second butterfly-shaped structure unit with high matching degree, and simultaneously controlling the equivalent capacitance of the varactor diodes on the first butterfly-shaped structure unit and the second butterfly-shaped structure unit, the continuous phase modulation of the incident electromagnetic wave is realized, and the modulation accuracy of the control metasurface when modulating the electromagnetic wave is greatly improved, so that the effect of jamming the SAR radar is improved.

Description

Technical Field

[0001] This invention relates to the field of signal processing technology, and in particular to a method, apparatus, device, and medium for SAR composite phase modulation interference based on a phase-tunable metasurface. Background Technology

[0002] Synthetic Aperture Radar (SAR) possesses advantages such as all-weather, all-day operation, strong penetration capability, long-range, and high-resolution Earth observation. It can provide rich information on the electromagnetic scattering characteristics of the Earth's surface and is an important component of strategic reconnaissance and battlefield surveillance systems. It plays a vital role in electronic warfare, target reconnaissance, and operational mapping. The development and application of SAR systems pose a serious threat to the military deployment, operational status, and wartime survivability of important friendly targets. Therefore, researching effective jamming and countermeasures against SAR imaging characteristics has become an urgent priority in the field of electronic warfare.

[0003] Depending on the source of the jamming energy, SAR jamming mainly includes active jamming and passive jamming. Active jamming is characterized by high flexibility, multiple jamming patterns, and good jamming effect. According to the different methods of jamming, active jamming is divided into suppression jamming and deception jamming. Suppression jamming refers to transmitting high-power incoherent jamming signals to the SAR system through jammers, which greatly reduces the signal-to-noise power ratio received by the radar. However, this type of method requires high power. Passive jamming mainly relies on reflecting or absorbing enemy electromagnetic waves to form jamming. Therefore, its jamming effect is often limited by a variety of factors. For example, when the frequency, polarization, or intensity of enemy electromagnetic waves changes, passive jamming equipment usually cannot provide an effective jamming effect.

[0004] The emergence and development of electromagnetic metasurfaces have provided new design methods for improving SAR jamming technology. Benefiting from the ability of electromagnetic metasurfaces to flexibly control important parameters such as electromagnetic wave delay, amplitude, phase, and frequency, they only need to modulate the incident electromagnetic wave to achieve jamming. Currently, modulated metasurfaces mainly include transmission phase type, geometric phase type, and circuit structure type. Transmission phase type metasurfaces primarily achieve phase modulation by controlling the dynamic phase during electromagnetic wave propagation. When an electromagnetic wave propagates in a material with a specific dielectric constant and permeability, its dynamic phase changes, thus achieving phase modulation. Geometric phase type metasurfaces generate geometric phase through the rotation of a patterned structure, thereby achieving phase modulation of the electromagnetic wave. Circuit structure type metasurfaces mainly achieve phase modulation of the electromagnetic wave by generating the circuit phase through the equivalent LC resonance of the patterned structure. However, these types of modulated metasurfaces typically require highly complex and well-designed structures to modulate the dynamic and circuit phases during the modulation process. This reduces the modulation accuracy of the modulated metasurface when modulating electromagnetic waves, thus reducing the effectiveness of SAR radar jamming. Summary of the Invention

[0005] This invention provides a SAR composite phase modulation interference method based on a phase-tunable metasurface. This method can solve the problem that existing methods usually require the design of highly compatible and complex structures to achieve modulation of the dynamic phase and circuit phase during the modulation process. This reduces the modulation accuracy of the metasurface when performing electromagnetic wave modulation, thereby reducing the effectiveness of SAR radar interference.

[0006] This invention provides a SAR composite phase modulation interference method based on a phase-tunable metasurface, comprising the following steps:

[0007] A phase-tuning metasurface is designed and installed on the surface of the protected target; the phase-tuning metasurface is composed of multiple periodically arranged metasurface units;

[0008] The metasurface unit includes a metal ground plane, a first metal substrate on the top surface of the metal ground plane, a first butterfly-shaped structural unit on the top surface of the first metal substrate, a second metal substrate on the top surface of the first butterfly-shaped structural unit, and a second butterfly-shaped structural unit on the top surface of the second metal substrate; the first butterfly-shaped structural unit and the second butterfly-shaped structural unit are used to control the phase, amplitude, and polarization of electromagnetic waves incident on the metasurface unit;

[0009] A varactor diode is provided at the intersection of the first butterfly structure unit and the intersection of the second butterfly structure unit. By changing the voltage applied to both sides of the first and second butterfly structure units, the equivalent capacitance of the varactor diode is adjusted in real time to make the phase of the electromagnetic wave incident on the metasurface unit continuously change.

[0010] The phase-modulated metasurface receives the transmitted signal from the SAR radar, performs slow-time cosine phase modulation and slow-time multi-phase segmented modulation on the transmitted signal, and reflects it. The reflected signal is used to deceive and interfere with the SAR radar.

[0011] Preferably, the first butterfly structure unit and the second butterfly structure unit are arranged at a 90-degree angle, and bias lines are provided on both sides of the first butterfly structure unit and the second butterfly structure unit. The bias lines are used to provide DC voltage or current to the metal square ring to change the capacitance value of the varactor diode, so as to dynamically control the electromagnetic wave modulation of the metasurface.

[0012] Preferably, the slow-time cosine phase modulation and slow-time multi-phase segmented modulation of the transmitted signal include:

[0013] When the SAR radar's transmitted signal is incident on the phase-tuning metasurface, the voltages applied to the bias lines on both sides of the first and second butterfly structure units are changed respectively, so that the voltages on both sides of the varactor diodes on the first and second butterfly structure units are changed respectively, thereby controlling the equivalent capacitance of the varactor diodes on the first and second butterfly structure units in real time. The electromagnetic wave incident on the phase-tuning metasurface is subjected to slow-time cosine phase modulation and slow-time multi-phase segmented modulation respectively, and the cosine phase modulation signal and multi-phase segmented modulation signal are obtained respectively.

[0014] The cosine phase modulation signal is:

[0015] p1(t m )=exp[jβcos(2πf1t m )];

[0016] Where: p1(t) m ) represents a cosine phase modulated signal; t m This indicates the slow time; β and f1 represent the modulation index and modulation frequency of the cosine phase modulated signal, respectively.

[0017] The multi-phase segmented modulation signal is:

[0018]

[0019] Where: p2(t) m () represents a multi-phase segmented modulation signal; * represents a convolution operation; τ,T,f2=1 / T,φ p P and N represent the segment duration, modulation period, modulation frequency, modulation phase, number of intra-pulse phase segments, and number of repetitions of the multi-phase segmented modulation signal, respectively.

[0020] The cosine phase modulation signal and the multi-phase segmented modulation signal form a composite phase modulation signal, wherein the composite phase modulation signal is:

[0021] p(t m )=p1(t m )×p2(t m );

[0022] Where: p(t) m ) represents a composite phase modulation signal.

[0023] Preferably, the formation of the reflected signal includes:

[0024] A phase-modulated metasurface on a stationary target receives the transmitted signal from a SAR radar and performs slow-time cosine phase modulation and slow-time multi-phase segmented modulation on the transmitted signal to obtain the cosine phase modulated signal and the multi-phase segmented modulation signal, so as to generate a composite phase modulated signal.

[0025] The spectrum of the composite phase modulation signal in the frequency domain is extracted. The spectrum of the composite phase modulation signal is copied multiple times in the azimuth direction of the protected target. The multiple different copied spectra are used to replace the spectrum of the composite phase modulation signal in turn to form multiple harmonic components of the composite phase modulation signal. The multiple harmonic components are then combined to form a composite phase interference signal, which is a reflected signal.

[0026] Preferably, the composite phase interference signal is:

[0027]

[0028] Among them: J n (β) represents the first-order n-th order Bessel function; f1 represents the modulation frequency of the cosine phase modulated signal; f2 represents the modulation frequency of the multi-phase segmented modulated signal; nf1+mf2 represents the spectral offset of the composite phase interference signal.

[0029] Preferably, the deception jamming of the SAR radar includes:

[0030] SAR radar receives composite phase interference signals and performs range-direction matched filtering, range migration correction, and clutter suppression on the interference signals. It forms a two-way false target string along the azimuth direction of the protected target in the interference image, thereby interfering with the SAR radar.

[0031] The offset of the mn-th false target in the orientation dimension is:

[0032]

[0033] Where: nf1+mf2 represents the spectral offset of the composite phase interference signal; f1 represents the modulation frequency of the cosine phase modulated signal; f2 represents the modulation frequency of the multi-phase segmented modulated signal; and γ represents the Doppler modulation frequency.

[0034] This invention also provides a SAR composite phase modulation jamming device based on a phase-tunable metasurface, comprising:

[0035] The design module is used to design phase-controlled metasurfaces and install them on the surface of the protected target; the phase-controlled metasurface is composed of multiple periodically arranged metasurface units;

[0036] The metasurface unit includes a metal ground plane, a first metal substrate on the top surface of the metal ground plane, a first butterfly-shaped structural unit on the top surface of the first metal substrate, a second metal substrate on the top surface of the first butterfly-shaped structural unit, and a second butterfly-shaped structural unit on the top surface of the second metal substrate; the first butterfly-shaped structural unit and the second butterfly-shaped structural unit are used to control the phase, amplitude, and polarization of electromagnetic waves incident on the metasurface unit;

[0037] A varactor diode is provided at the intersection of the first butterfly structure unit and the intersection of the second butterfly structure unit. By changing the voltage applied to both sides of the first and second butterfly structure units, the equivalent capacitance of the varactor diode is adjusted in real time to make the phase of the electromagnetic wave incident on the metasurface unit continuously change.

[0038] The SAR radar jamming module uses a phase-modulated metasurface to receive the transmitted signal from the SAR radar. It performs slow-time cosine phase modulation and slow-time multi-phase segmented modulation on the transmitted signal and reflects it, thereby deceiving and jamming the SAR radar through the reflected signal.

[0039] This invention also provides an electronic device, including a memory and a processor;

[0040] The memory is used to store computer programs;

[0041] When the processor executes the computer program stored in the memory, it implements the steps of the SAR composite phase modulation interference method based on a phase-tunable metasurface as described above.

[0042] This invention also provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of the SAR composite phase modulation interference method based on a phase-tunable metasurface as described above.

[0043] This invention provides a SAR composite phase modulation interference method based on a phase-tunable metasurface, which has the following advantages compared with the prior art:

[0044] The phase-modulated metasurface designed in this invention employs a multi-layered metal substrate and a butterfly-shaped structural unit design, making the entire structure compact and easy to integrate into the surface of the protected target. A varactor diode is introduced as the modulation element. By changing the voltage applied to both sides of the first and second butterfly-shaped structural units, the equivalent capacitance of the varactor diode can be adjusted in real time, thereby achieving continuous modulation of the phase of the incident electromagnetic wave. This invention achieves continuous phase modulation of the incident electromagnetic wave simply by designing highly compatible first and second butterfly-shaped structural units and simultaneously adjusting the equivalent capacitance of the varactor diodes on both units. This significantly improves the modulation accuracy of the metasurface during electromagnetic wave modulation, thereby enhancing the effectiveness against SAR radar interference.

[0045] Furthermore, the phase-tuned metasurface can receive the transmitted signals of SAR radar and reflect them back after processing the signals through slow-time cosine phase modulation and slow-time multi-phase segmented modulation. This processing method can generate radar images that are different from the real targets, thereby achieving deception and interference against SAR radar. It is also highly efficient and covert, and can effectively protect targets from the threat of radar detection and identification. Attached Figure Description

[0046] Figure 1 A schematic diagram of the overall process of the SAR composite phase modulation interference method based on a phase-tunable metasurface provided in an embodiment of the present invention;

[0047] Figure 2 A schematic diagram of the interference model for the SAR composite phase modulation interference method based on a phase-tunable metasurface provided in an embodiment of the present invention;

[0048] Figure 3 The diagram shows the design of a phase-tunable metasurface for a SAR composite phase modulation interference method based on a phase-tunable metasurface provided in this embodiment of the invention; (a) is a structural diagram of the metasurface; and (b) is a schematic diagram of the metasurface array.

[0049] Figure 4 A schematic diagram of the original SAR imaging result under interference-free conditions for the SAR composite phase modulation interference method based on a phase-tunable metasurface provided in an embodiment of the present invention;

[0050] Figure 5 A schematic diagram of the composite modulation phase distribution of the SAR composite phase modulation interference method based on a phase-tunable metasurface provided in an embodiment of the present invention;

[0051] Figure 6 This is a schematic diagram of the interference imaging results of the SAR composite phase modulation interference method based on a phase-tunable metasurface provided in an embodiment of the present invention. Detailed Implementation

[0052] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0053] See Figure 1 This invention provides a SAR composite phase modulation interference method based on a phase-tunable metasurface, comprising the following steps:

[0054] Step 1: Design of a phase-tunable metasurface.

[0055] Step 2: Establishment of a composite phase modulation signal model based on a phase-tunable metasurface.

[0056] Step 3: Construction of SAR interference signal model based on phase-tunable metasurface.

[0057] Step 4: SAR imaging processing and imaging interference effect analysis.

[0058] The design of the phase-tunable metasurface in step one is as follows:

[0059] First, a double-layer butterfly-shaped metal structure is designed, and lumped elements—varactor diodes—are added between the butterfly-shaped metal gaps. By adjusting the voltage across the varactor diodes, the equivalent capacitance is changed, thereby enabling a continuous change in the phase of the incident electromagnetic wave. The designed electromagnetic metasurface unit structure and array structure are as follows: Figure 3 As shown, the array structure layout is achieved by periodically translating the unit structure in two dimensions, thereby realizing a complete two-dimensional electromagnetic metasurface array structure.

[0060] The establishment of the composite phase modulation signal model in step two is as follows:

[0061] Cosine phase modulation and multi-phase segmented modulation have superior interference effects in traditional active interference methods. This invention utilizes a phase-tunable metasurface to combine cosine phase modulation with multi-phase segmented modulation to generate a composite phase-modulated signal, which can be expressed as:

[0062] p(t m )=p1(t m )×p2(t m );

[0063] Where: t m Indicates slow time; p1(t) m) and p2(t m The following symbols represent the cosine phase modulated signal and the multi-phase segmented modulated signal, respectively, and their expressions are:

[0064] p1(t m )=exp[jβcos(2πf1t m )];

[0065]

[0066] Where: β and f1 represent the modulation index and modulation frequency of the cosine phase modulated signal, respectively; * represents the convolution operation; τ,T,f2=1 / T,φ p P and N represent the segment duration, modulation period, modulation frequency, modulation phase, number of intra-pulse phase segments, and number of repetitions of the multi-phase segmented modulation signal, respectively.

[0067] p(t m The frequency domain expression of ) is:

[0068]

[0069] Among them: J n (β) represents the first kind of nth-order Bessel function; the expression for B(m) is:

[0070]

[0071] As can be seen from the above equation, the spectrum of the composite phase-modulated signal is determined by J. n The "comb-like" spectrum is formed by combining the amplitudes of (β) and B(m).

[0072] Step three involves constructing the SAR interference signal model, specifically as follows:

[0073] SAR imaging interference model based on phase-tunable metasurface, such as Figure 2 As shown; a two-dimensional rectangular coordinate system XOR is established on the SAR data acquisition plane. The SAR system moves from the origin O along the X-axis at a constant speed V, and the direction perpendicular to the flight trajectory to the center of the observation scene is denoted as the R-axis; a phase-tunable metasurface is placed on the surface p of the protected target in the observation scene. t (x0,R0), where (x0,R0) represents the target location; the instantaneous slant range between the SAR system and the protected target can be expressed as:

[0074]

[0075] Where: t m Indicates the direction of time; R B =minR(t) m ).

[0076] Assume the LFM signal transmitted by the SAR system is represented as:

[0077]

[0078] in: Indicates distance in time; T r represents the pulse width; rect(·) represents the rectangular function; f0 represents the center frequency of the transmitted signal; μ represents the modulation frequency of the transmitted LFM signal.

[0079] A phase-tunable metasurface on the target surface intercepts the radar-transmitted signal and modulates it with interference. Since the metasurface itself does not actively radiate high-power signals, it avoids the drawbacks of traditional active jamming methods, such as high cost and easy exposure of the target area. Under external bias voltage control, the phase-tunable metasurface can achieve real-time modulation of the phase information of the transmitted signal and forward the modulated signal to the SAR imaging system. The SAR system detects and demodulates the received interference echo signal; its complex baseband interference signal can be expressed as:

[0080]

[0081] in: The expression for an unmodulated echo signal is:

[0082]

[0083] Where: A represents the complex reflection coefficient of the target; T a The time to synthesize the aperture is represented by λ; λ and c represent wavelength and speed of light, respectively.

[0084] The interference signal can be represented in the Doppler frequency domain as:

[0085]

[0086] As shown in the above equation, the spectrum of the interference signal is a multiple spectral copy of the original echo signal spectrum in the azimuth direction, with a spectral offset of nf1 + mf2; simultaneously, the amplitude of each harmonic component is affected by J. n Joint modulation of (β) and B(m).

[0087] Step four, SAR imaging processing and imaging interference effect analysis, are as follows:

[0088] After range-Doppler SAR imaging processing, the interference signal, after range-matched filtering and range migration correction, can be expressed as:

[0089]

[0090] Among them: Br This indicates the bandwidth of the transmitted signal.

[0091] The aforementioned interference signal is subjected to azimuth matched filtering to obtain the final interference SAR image, which is expressed as follows:

[0092]

[0093] in:

[0094] Among them: B a γ represents the Doppler bandwidth of the signal; γ represents the Doppler modulation frequency.

[0095] It can be seen that multiple false targets are generated along the azimuth direction in the jammed SAR image, and the offset of the mn-th false target in the azimuth dimension is:

[0096]

[0097] The specific experiment was as follows:

[0098] One reference target RT and three protected targets PT1-3 are set at the center of the imaging scene; range-Doppler SAR imaging processing is performed on the unmodulated radar echo to obtain the unmodulated raw SAR imaging result, such as... Figure 4 As shown, four targets with high focus quality can be observed in the SAR image.

[0099] Composite phase modulation of the echo signal from the protected target was performed using a phase-tunable metasurface. The modulation parameters were set as β = 1, f1 = 10 Hz, f2 = 37.5 Hz, and φ. p =0,0.2π,0.35π,0.8π, its composite modulation phase is as follows Figure 5 As shown; after range-Doppler imaging processing, the interference imaging result is obtained, as follows. Figure 6 As shown, it can be seen that after composite phase modulation processing based on the phase-tunable metasurface, the protected target PTi, (i=1,2,3) can generate false target strings in the azimuth direction, thereby interfering with subsequent SAR target detection and recognition, and achieving the purpose of deception and interference.

[0100] This invention utilizes a phase-tunable metasurface to perform slow-time phase modulation on radar signals through an external control system to generate SAR composite phase interference signals. By performing range-Doppler imaging processing on the SAR composite phase interference signals, theoretical analysis and experimental results show that this invention generates a string of false targets with flexible and controllable azimuth position and amplitude in the azimuth direction, with high flexibility, high fidelity, and low cost interference imaging effect, and has strong practical application value.

[0101] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A SAR composite phase modulation interference method based on a phase-tunable metasurface, characterized in that, Includes the following steps: A phase-tuning metasurface is designed and installed on the surface of the protected target; the phase-tuning metasurface is composed of multiple periodically arranged metasurface units; The metasurface unit includes a metal ground plane, a first metal substrate on the top surface of the metal ground plane, a first butterfly-shaped structural unit on the top surface of the first metal substrate, a second metal substrate on the top surface of the first butterfly-shaped structural unit, and a second butterfly-shaped structural unit on the top surface of the second metal substrate; the first butterfly-shaped structural unit and the second butterfly-shaped structural unit are used to control the phase, amplitude, and polarization of electromagnetic waves incident on the metasurface unit; A varactor diode is provided at the intersection of the first butterfly structure unit and the intersection of the second butterfly structure unit. By changing the voltage applied to both sides of the first and second butterfly structure units, the equivalent capacitance of the varactor diode is adjusted in real time to make the phase of the electromagnetic wave incident on the metasurface unit continuously change. The phase-modulated metasurface receives the transmitted signal from the SAR radar, performs slow-time cosine phase modulation and slow-time multi-phase segmented modulation on the transmitted signal and reflects it, and uses the reflected signal to deceive and interfere with the SAR radar. The first butterfly structure unit and the second butterfly structure unit are set at a 90-degree angle, and bias lines are provided on both sides of the first butterfly structure unit and the second butterfly structure unit. The bias lines are used to provide DC voltage or current to the metal square ring to change the capacitance value of the varactor diode, so as to dynamically control the electromagnetic wave modulation of the metasurface. The slow-time cosine phase modulation and slow-time multi-phase segmented modulation of the transmitted signal include: When the SAR radar's transmitted signal is incident on the phase-tuning metasurface, the voltages applied to the bias lines on both sides of the first and second butterfly structure units are changed respectively, so that the voltages on both sides of the varactor diodes on the first and second butterfly structure units are changed respectively, thereby controlling the equivalent capacitance of the varactor diodes on the first and second butterfly structure units in real time. The phase of the electromagnetic wave signal incident on the phase-tuning metasurface is subjected to slow-time cosine phase modulation and slow-time multi-phase segmented modulation respectively, and the cosine phase modulation signal and multi-phase segmented modulation signal are obtained respectively. The cosine phase modulation signal is: ； in: This represents a cosine phase modulated signal; Indicates slow time; and These represent the modulation index and modulation frequency of the cosine phase modulated signal, respectively. The multi-phase segmented modulation signal is: ； in: This indicates a multi-phase segmented modulation signal; This represents the convolution operation; These represent the segment duration, modulation period, modulation frequency, modulation phase, number of intra-pulse phase segments, and number of repetitions of a multi-phase segmented modulated signal, respectively. The cosine phase modulation signal and the multi-phase segmented modulation signal form a composite phase modulation signal, wherein the composite phase modulation signal is: ； in: Indicates a composite phase-modulated signal; The formation of the reflected signal includes: A phase-modulated metasurface on a stationary target receives the transmitted signal from a SAR radar and performs slow-time cosine phase modulation and slow-time multi-phase segmented modulation on the transmitted signal to obtain the cosine phase modulated signal and the multi-phase segmented modulation signal, so as to generate a composite phase modulated signal. The spectrum of the composite phase modulation signal in the frequency domain is extracted. The spectrum of the composite phase modulation signal is copied multiple times in the azimuth direction of the protected target. The multiple different copied spectra are used to replace the spectrum of the composite phase modulation signal in turn to form multiple harmonic components of the composite phase modulation signal. The multiple harmonic components are then combined to form a composite phase interference signal, which is a reflected signal. The composite phase interference signal is: ； in: Indicates the first type n Bessel function of order 1; f 1 represents the modulation frequency of the cosine phase modulated signal; f 2 represents the modulation frequency of the multi-phase segmented modulation signal; This represents the spectral offset of the composite phase interference signal; The deception and jamming of SAR radar includes: SAR radar receives composite phase interference signals and performs range-direction matched filtering, range migration correction, and clutter suppression on the interference signals. It forms a two-way false target string along the azimuth direction of the protected target in the interference image, thereby interfering with the SAR radar. Among them, the first m - n The offset of each false target in the orientation dimension is: ； in: This indicates the spectral offset of the composite phase interference signal; f 1 represents the modulation frequency of the cosine phase modulated signal; f 2 represents the modulation frequency of the multi-phase segmented modulation signal; This indicates the Doppler modulation frequency.

2. A SAR composite phase modulation jamming device based on a phase-tunable metasurface, characterized in that, include: Design module for designing phase-controlled metasurfaces and installing them on the surface of the protected target; The phase-tuning metasurface is composed of multiple periodically arranged metasurface units; The metasurface unit includes a metal ground plane, a first metal substrate on the top surface of the metal ground plane, a first butterfly-shaped structural unit on the top surface of the first metal substrate, a second metal substrate on the top surface of the first butterfly-shaped structural unit, and a second butterfly-shaped structural unit on the top surface of the second metal substrate; the first butterfly-shaped structural unit and the second butterfly-shaped structural unit are used to control the phase, amplitude, and polarization of electromagnetic waves incident on the metasurface unit; A varactor diode is provided at the intersection of the first butterfly structure unit and the intersection of the second butterfly structure unit. By changing the voltage applied to both sides of the first and second butterfly structure units, the equivalent capacitance of the varactor diode is adjusted in real time to make the phase of the electromagnetic wave incident on the metasurface unit continuously change. The SAR radar jamming module uses a phase-modulated metasurface to receive the transmitted signal from the SAR radar, performs slow-time cosine phase modulation and slow-time multi-phase segmented modulation on the transmitted signal, and reflects it. The reflected signal is used to deceive and jam the SAR radar. The first butterfly structure unit and the second butterfly structure unit are set at a 90-degree angle, and bias lines are provided on both sides of the first butterfly structure unit and the second butterfly structure unit. The bias lines are used to provide DC voltage or current to the metal square ring to change the capacitance value of the varactor diode, so as to dynamically control the electromagnetic wave modulation of the metasurface. The slow-time cosine phase modulation and slow-time multi-phase segmented modulation of the transmitted signal include: When the SAR radar's transmitted signal is incident on the phase-tuning metasurface, the voltages applied to the bias lines on both sides of the first and second butterfly structure units are changed respectively, so that the voltages on both sides of the varactor diodes on the first and second butterfly structure units are changed respectively, thereby controlling the equivalent capacitance of the varactor diodes on the first and second butterfly structure units in real time. The phase of the electromagnetic wave signal incident on the phase-tuning metasurface is subjected to slow-time cosine phase modulation and slow-time multi-phase segmented modulation respectively, and the cosine phase modulation signal and multi-phase segmented modulation signal are obtained respectively. The cosine phase modulation signal is: ； in: This represents a cosine phase modulated signal; Indicates slow time; and These represent the modulation index and modulation frequency of the cosine phase modulated signal, respectively. The multi-phase segmented modulation signal is: ； in: This indicates a multi-phase segmented modulation signal; This represents the convolution operation; These represent the segment duration, modulation period, modulation frequency, modulation phase, number of intra-pulse phase segments, and number of repetitions of a multi-phase segmented modulated signal, respectively. The cosine phase modulation signal and the multi-phase segmented modulation signal form a composite phase modulation signal, wherein the composite phase modulation signal is: ； in: Indicates a composite phase-modulated signal; The formation of the reflected signal includes: A phase-modulated metasurface on a stationary target receives the transmitted signal from a SAR radar and performs slow-time cosine phase modulation and slow-time multi-phase segmented modulation on the transmitted signal to obtain the cosine phase modulated signal and the multi-phase segmented modulation signal, so as to generate a composite phase modulated signal. The spectrum of the composite phase modulation signal in the frequency domain is extracted. The spectrum of the composite phase modulation signal is copied multiple times in the azimuth direction of the protected target. The multiple different copied spectra are used to replace the spectrum of the composite phase modulation signal in turn to form multiple harmonic components of the composite phase modulation signal. The multiple harmonic components are then combined to form a composite phase interference signal, which is a reflected signal. The composite phase interference signal is: ； in: Indicates the first type n Bessel function of order 1; f 1 represents the modulation frequency of the cosine phase modulated signal; f 2 represents the modulation frequency of the multi-phase segmented modulation signal; This represents the spectral offset of the composite phase interference signal; The deception and jamming of SAR radar includes: SAR radar receives composite phase interference signals and performs range-direction matched filtering, range migration correction, and clutter suppression on the interference signals. It forms a two-way false target string along the azimuth direction of the protected target in the interference image, thereby interfering with the SAR radar. Among them, the first m - n The offset of each false target in the orientation dimension is: ； in: This indicates the spectral offset of the composite phase interference signal; f 1 represents the modulation frequency of the cosine phase modulated signal; f 2 represents the modulation frequency of the multi-phase segmented modulation signal; This indicates the Doppler modulation frequency.

3. An electronic device, characterized in that, Including memory and processor; The memory is used to store computer programs; When the processor executes the computer program stored in the memory, it implements the steps of the SAR composite phase modulation interference method based on a phase-tunable metasurface as described in claim 1.

4. A computer-readable storage medium, characterized in that, Used to store a computer program, which, when executed by a processor, implements the steps of the SAR composite phase modulation interference method based on a phase-tunable metasurface as described in claim 1.

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