Method, system and device for constructing multi-domain feature model of plasma sheath coated target broadband radar echo and medium

Abstract

The application discloses a method, system and device for constructing a multi-domain characteristic model of a plasma sheath coated target wideband radar echo, and a medium. ref The method comprises the following steps: calculating a plasma sheath wideband radar reflected electromagnetic wave E(t); establishing a plasma sheath coated target wideband time-domain echo model Echo(t); and establishing a multi-domain characteristic model of a plasma sheath coated target wideband radar echo. The system, the device and the medium are used for implementing the method for constructing the multi-domain characteristic model of the plasma sheath coated target wideband radar echo. The peak value distribution of a plasma sheath coated target wideband radar incident reflection coefficient is obtained through peak value searching, a wideband radar signal incident plasma sheath coupling speed extraction method is proposed, a plasma sheath wideband radar reflection signal is obtained, and the coupling mechanism of the plasma sheath and the radar signal under a large bandwidth system is disclosed. The application provides a model basis for studying the multi-domain characteristic influence law of the plasma sheath on the wideband radar signal, and has the characteristics of high modeling precision and low modeling difficulty.

Description

Technical Field

[0001] This invention relates to the field of broadband radar target detection technology, specifically to a method, system, device, and medium for constructing a multi-domain feature model of broadband radar echoes from a target encased in a plasma sheath. Background Technology

[0002] When a hypersonic vehicle in near space flies at speeds above Mach 10, the air in the direction of the vehicle's flight path is violently compressed at the vehicle's stagnation point, generating a shock wave. Under the extreme conditions of the shock wave, kinetic energy is converted into thermal energy, resulting in extremely high temperatures at the stagnation point. Under high temperature and high pressure conditions, the gas molecules around the vehicle undergo a series of reactions, producing a large number of ions that envelop the surface of the hypersonic vehicle. This non-uniform plasma layer is known as the plasma sheath.

[0003] The dielectric properties of the plasma sheath modulate the incident electromagnetic waves, causing amplitude attenuation and phase distortion. Simultaneously, the flow field parameters vary significantly at different reference positions of the aircraft. Influenced by the high-speed incoming flow, the plasma sheath and the aircraft undergo relative displacement, forming a velocity field within the non-uniform plasma. The velocity field distribution characteristics of this non-uniform plasma result in varying coupling velocities for the echo introduced at different target positions and incident depths. This causes the one-dimensional range image to expand and shift, preventing proper focusing and impacting subsequent target identification and detection.

[0004] The existing approach involves modeling the echo of a plasma sheath using narrowband radar signals, obtaining a one-dimensional range profile of the radar echo through pulse compression, and then performing time-frequency domain analysis on the echo of the target covered by the plasma sheath using algorithms such as WVD. However, this approach is based on multi-domain feature analysis of narrowband radar echoes. Modern high-precision radars use broadband radar signals with a large frequency span and strong differences between frequency components, making them unsuitable for analysis using narrowband models. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a method, system, device, and medium for constructing a multi-domain feature model of broadband radar echoes from targets covered by plasma sheaths. This method obtains the peak distribution of the reflection coefficient of broadband radar signals incident on the plasma sheath from targets covered by plasma sheaths through peak search, proposes a method for extracting the coupling velocity of broadband radar signals incident on the plasma sheath, obtains a broadband time-domain echo model of targets covered by plasma sheaths, establishes a multi-domain feature model of broadband radar echoes from targets covered by plasma sheaths, reveals the influence of the plasma sheath on the multi-domain features of broadband radar signals, supplements existing multi-domain feature analysis of radar echoes from targets covered by plasma sheaths, fills the gap in multi-domain feature analysis of broadband radar echoes from targets covered by plasma sheaths, improves the application scenarios of multi-domain feature analysis of radar echoes from targets covered by plasma sheaths, and features high modeling accuracy.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The method for constructing a multi-domain feature model of broadband radar echoes from targets covered by plasma sheaths includes the following steps:

[0008] Step 1: Calculate the electromagnetic wave E reflected by the broadband radar from the plasma sheath. ref (t);

[0009] Step 2: Based on the broadband radar reflected electromagnetic wave E obtained in Step 1, ref (t), establish a broadband time-domain echo model Echo(t) for the target covered by a plasma sheath;

[0010] Step 3: Based on the broadband time-domain echo model Echo(t) of the plasma sheath-covered target obtained in Step 2, establish a multi-domain feature model of the broadband radar echo of the plasma sheath-covered target.

[0011] Step 1 calculates the broadband radar reflected electromagnetic wave E from the plasma sheath. ref The specific process of (t) is as follows:

[0012] Step 1.1, calculate the termination frequency f of the broadband electromagnetic wave. end The specific formula is as follows:

[0013] f end =f c +B

[0014] In the formula, f c B represents the starting frequency of the broadband electromagnetic wave, and B represents the bandwidth of the broadband electromagnetic wave.

[0015] Step 1.2: Using the non-uniform plasma layering model at the m-th reference position, the electron density n of the n-th plasma layer is determined. e,n(m), calculate the characteristic frequency f of the nth layer plasma at the mth reference position. p,n (m), the specific formula is:

[0016]

[0017] In the formula, m is the reference position number, m = 1, 2, ..., M, M is the total number of reference positions, e represents the input unit charge, and m e ε0 represents the electron mass, and ε0 represents the vacuum permittivity.

[0018] Step 1.3, using the broadband electromagnetic wave termination frequency f obtained in Step 1.1 end The characteristic frequency f of the nth layer plasma at the mth reference position obtained in step 1.2 p,n (m), based on different situations when broadband radar signals are incident on non-uniform plasma, the diversity signal frequency f under different conditions is obtained. i (m);

[0019] Step 1.4, using the diversity signal frequency f obtained in step 1.3 i (m), calculate the frequency f of each diversity signal at the m-th reference position. i (m) corresponds to the coupling Doppler frequency f d,i (m), the specific formula is:

[0020]

[0021] In the formula, v n (m) represents the flow field velocity at the m-th reference position, f i (m) represents the frequency of the diversity signal at the m-th reference position;

[0022] Step 1.5, using the coupling Doppler frequency f obtained in step 1.4 d,i (m), calculate the broadband radar-reflected electromagnetic wave E of the nth layer of plasma in the local plasma sheath at the m-th reference position. R (t,n,m): Assuming the broadband echo signal can be divided into I diversity signals, based on the spatial distribution characteristics of the reflection coefficient of the broadband radar signal within the local plasma sheath, the broadband radar reflected electromagnetic wave E of the nth layer of plasma in the local plasma sheath is solved by vector accumulation. R (t,n,m), the specific formula is:

[0023]

[0024] In the formula, R i,n (m) represents the reflection coefficient of the i-th diversity signal at the n-th layer, |R i,n (m)| represents the amplitude modulation of the i-th diversity signal at the n-th layer. This represents the phase modulation of the i-th diversity signal in the n-th plasma layer;

[0025] Step 1.6: Utilize the broadband radar-reflected electromagnetic wave E of the nth layer plasma of the local plasma sheath obtained in Step 1.5. R (t,n,m), calculate the electromagnetic wave E reflected by the local plasma sheath under the large bandwidth system at the m-th reference position. R (t,m), the specific formula is:

[0026]

[0027] Step 1.7, based on the electromagnetic wave E reflected by the local plasma sheath under the large bandwidth system at the m-th reference position obtained in Step 1.6. R (t,m) represents the vector superposition of locally reflected electromagnetic waves from the plasma sheath at M reference positions under a large bandwidth regime, yielding the broadband radar reflected electromagnetic wave E of the target enveloped by the plasma sheath. R (t), the specific formula is:

[0028]

[0029] Step 1.8, based on the plasma sheath coating of the target broadband radar reflected electromagnetic wave E obtained in Step 1.7. R (t) and the typical peak values ​​of the local plasma sheath reflection coefficient distribution spectrum and the corresponding flow field velocities at each peak position are used to calculate the broadband radar reflected electromagnetic wave E of the plasma sheath. ref (t):

[0030]

[0031] In the formula, M represents the total number of reference positions, Q represents the number of peaks in the reflectance coefficient distribution spectrum at the m-th position, and R... q (m) represents the q-th peak reflectance at the m-th reference position, f q (m) represents the diversity signal frequency corresponding to the q-th peak position, f d,q (m) represents the Doppler frequency generated by the velocity field of the layer where the diversity signal is coupled at the q-th peak position, which is found after simulation.

[0032] The specific process of establishing the broadband time-domain echo model Echo(t) of the plasma sheath-encased target in step 2 is as follows:

[0033] Step 2.1, determine the linear frequency modulated pulse signal radar model s(t), the specific model is as follows:

[0034]

[0035] In the formula, A represents the amplitude of the radar signal, k represents the frequency modulation frequency of the radar signal, and T... p The pulse width of the broadband radar signal is represented by n(t), and the noise signal is represented by n(t).

[0036] Step 2.2, based on the electromagnetic wave E reflected by the local plasma sheath under the large bandwidth system at the m-th reference position obtained in Step 1.6. R Using the linear frequency modulated pulse signal radar model s(t) obtained in step 2.1, a broadband time-domain echo model of the plasma sheath at the m-th reference position is modeled, resulting in the local broadband time-domain echo model Echo(t,m) of the plasma sheath-covered target at the m-th reference position. The specific model is as follows:

[0037]

[0038] In the formula, k represents the frequency modulation frequency of the radar signal, and T p,q (m) represents the pulse width of the diversity signal corresponding to the q-th peak position, r m f represents the m-th reference position of the target covered by the plasma sheath. d,q (m) represents the coupled Doppler frequency corresponding to the diversity signal frequency at the q-th peak position;

[0039] Step 2.3: Calculate the pulse width T of the diversity signal corresponding to the qth peak position at the m-th reference position in the local plasma sheath reflection coefficient distribution spectrum. p,q (m);

[0040] Step 2.4, using the pulse width T obtained in step 2.3 p,q The local broadband time-domain echo model Echo(t,m) obtained in step 2.2 is vector-superimposed on the local broadband time-domain echo models of the plasma sheath at M reference positions to obtain the broadband time-domain echo model Echo(t) of the plasma sheath-enclosed target. The specific model is as follows:

[0041]

[0042] The broadband time-domain echo multi-domain feature model of the target covered by the plasma sheath in step 3 includes a broadband radar one-dimensional range image analysis model, a two-dimensional time-frequency domain analysis model, and a two-dimensional time-delay-Doppler domain analysis model:

[0043] The broadband radar one-dimensional range profile analysis model is specifically as follows: Based on pulse compression processing, a broadband radar echo range domain characterization of a plasma sheath-encased target is obtained:

[0044]

[0045]

[0046] The specific two-dimensional time-frequency domain analysis model is as follows: Based on the Wegener transform, the two-dimensional time-frequency of the broadband radar echo of the plasma sheath-covered target is solved, and characterized as follows:

[0047]

[0048] In the formula, P echo =A 2 ×|R q (m)| 2 The term represents the time-frequency amplitude of the modulated broadband radar signal after the Wegener transform, ct is the sum of all outputs after the Wegener transform, including cross terms and noise terms, and the peak position of the impulse function contains the intra-pulse velocity information coupled with the broadband echo signal.

[0049] The specific two-dimensional time delay-Doppler domain analysis model is as follows: Based on a fuzzy function, the two-dimensional time delay-Doppler frequency of the broadband radar echo from the plasma sheath-encased target is solved, and characterized as follows:

[0050]

[0051] In the formula, τ represents the time delay, and ξ represents the frequency offset, i.e. the intrapulse Doppler frequency. When the fuzzy function processing result is the maximum value, the frequency offset ξ is a series of straight lines related to the intrapulse coupling velocity and the position of each reference position.

[0052] In step 1.3, the diversity signal frequency f under different conditions is obtained based on the different situations when the broadband radar signal is incident on the non-uniform plasma. i (m), specifically:

[0053] (1) When the termination frequency of the incident broadband electromagnetic wave is less than the characteristic frequency of the outermost layer of the non-uniform plasma, i.e., f end <f p,1 When (m), broadband electromagnetic waves are reflected only in the outermost layer of the plasma;

[0054] (2) When the initial frequency of the incident broadband electromagnetic wave is greater than the peak characteristic frequency of the non-uniform plasma, i.e., f pmax (m)<f c At that time, broadband electromagnetic waves completely penetrate the non-uniform plasma, and the broadband electromagnetic waves are reflected on the surface of the aircraft, that is, transparent transmission is generated.

[0055] (3) When the frequency range of the incident broadband electromagnetic wave is f p,1 (m)<f c <f end <f pmaxWhen (m), the broadband electromagnetic wave is incident entirely into the non-uniform plasma, with different frequency components corresponding to different incident depths, according to f i (m)=f p,n (m) Design the diversity signal, where the diversity signal frequency f i (m) represents the characteristic frequencies of each plasma layer within the intersection range of the broadband radar signal frequency range and the plasma characteristic frequency gradient, f p,n (m) represents the characteristic frequency of the nth plasma layer, i represents the carrier frequency sequence number of the diversity signal, i = 0, 1, 2, ..., I, I represents the total number of diversity signals obtained after broadband electromagnetic wave frequency diversity processing, f I (m) represents the maximum diversity frequency obtained after broadband electromagnetic wave frequency diversity processing;

[0056] (4) When the frequency range of the incident broadband electromagnetic wave is f c <f p,1 (m)<f end <f pmax When (m), a broadband electromagnetic wave component is incident into the non-uniform plasma. Different frequency components correspond to different incident depths, according to f i (m)=f p,n (m) Design diversity signals;

[0057] (5) When the frequency range of the incident broadband electromagnetic wave is f p,1 (m)<f c <f pmax (m)<f end When broadband electromagnetic waves are incident on the interior of a non-uniform plasma, some diversity signals penetrate the non-uniform plasma and are transmitted to the target surface, resulting in transparent transmission and electromagnetic shielding effects.

[0058] In step 2.3, the pulse width T of the diversity signal corresponding to the m-th reference position and the q-th peak position in the local plasma sheath reflection coefficient distribution spectrum is... p,q The solution method for (m) is as follows:

[0059] Step 2.3.1, let x be the number of local plasma sheath layers corresponding to the q-th peak at the m-th reference position, where x = 0, 1, 2, ..., N. Then the characteristic frequency difference Δf between two adjacent plasma layers is... p,x (m) is:

[0060] Δf p,x (m)=f p,x+1 (m)-f p,x (m)

[0061] In the formula, f p,x (m) represents the characteristic frequency of the x-th layer plasma at the m-th reference position, fp,x+1 (m) represents the characteristic frequency of the plasma in the (x+1)th layer at the m-th reference position, Δf p,x (m) represents the characteristic frequency difference between two adjacent plasma layers;

[0062] Step 2.3.2, using the characteristic frequency difference Δf between two adjacent plasma layers obtained in step 2.3.1. p,x (m), calculate the pulse width T of the diversity signal corresponding to the q-th peak position. p,q (m):

[0063]

[0064] In the formula, k represents the frequency modulation frequency of the radar signal, and f p,x (m) represents the characteristic frequency of the x-th layer plasma at the m-th reference position, f p,x+1 (m) represents the characteristic frequency of the plasma in the (x+1)th layer at the m-th reference position, Δf p,x (m) represents the characteristic frequency difference between two adjacent plasma layers.

[0065] A system for constructing a multi-domain feature model of broadband radar echoes from targets covered by plasma sheaths includes:

[0066] Plasma sheath broadband radar reflected electromagnetic wave modeling module: used to calculate the electromagnetic wave E reflected by plasma sheath broadband radar. ref (t);

[0067] Plasma sheath-encased target broadband time-domain echo modeling module: Utilizing the broadband radar reflection of electromagnetic waves E by the plasma sheath ref (t), establish a broadband time-domain echo model Echo(t) for the target covered by a plasma sheath;

[0068] Multi-domain feature modeling module for broadband radar echo of plasma sheath-encased target: Using the broadband time-domain echo model Echo(t) of plasma sheath-encased target, a multi-domain feature model of broadband radar echo of plasma sheath-encased target is established.

[0069] The equipment for constructing a multi-domain feature model of broadband radar echoes from targets encased in plasma sheaths includes:

[0070] Memory: Used to store the computer program that implements the method for constructing the multi-domain feature model of the broadband radar echo of the plasma sheath-encased target;

[0071] A processor is used to implement the method for constructing the multi-domain feature model of the broadband radar echo of the plasma sheath-encased target when executing the computer program.

[0072] A computer-readable storage medium comprising:

[0073] The computer-readable storage medium stores a computer program that, when executed by a processor, enables a method for constructing a multi-domain feature model of a broadband radar echo of a target covered by a plasma sheath.

[0074] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0075] 1. In step 1 of this invention, by establishing a broadband radar signal frequency domain diversity model, obtaining the flow field velocity corresponding to the peak position obtained after the superposition of the vectors of each diversity signal incident on the plasma sheath, solving the Doppler frequency of the flow field velocity corresponding to the peak position, and establishing a broadband radar reflection electromagnetic wave model of the plasma sheath-encased target, the gap in broadband radar reflection electromagnetic wave modeling is filled, providing a basis for carrying out calculation of the broadband time domain echo model of the plasma sheath-encased target. Compared with the prior art, it has the characteristics of fast calculation speed and high calculation efficiency.

[0076] 2. In step 2 of the present invention, based on the electromagnetic wave model of the broadband radar reflection of the target covered by the plasma sheath, the expression of the echo signal of the target covered by the plasma sheath is solved, which fills the gap in the modeling of the time domain model of the broadband radar echo of the target covered by the plasma sheath. It provides model support for the extraction of multi-domain features of the echo signal and the revelation of the peak broadening mechanism of the one-dimensional range image. Compared with the prior art, it has the characteristics of low modeling difficulty and high modeling accuracy.

[0077] 3. In step 3 of this invention, the peak interval and peak broadening between domains are extracted through Wegener transform, which provides a research basis for quantitatively studying the influence of different flight altitudes, speeds, carrier frequencies, pulse widths, and bandwidths on the characteristics of broadband radar echoes in each domain, and fills the gap in the modeling of multi-domain feature models for broadband radar.

[0078] In summary, compared with existing technologies, this invention obtains the peak distribution of the incident reflection coefficient of a broadband radar on a target covered by a plasma sheath based on peak search, proposes a method for extracting the coupling velocity of a broadband radar signal incident on a plasma sheath, obtains the reflected electromagnetic wave from the broadband radar of the plasma sheath, and reveals the coupling mechanism between the plasma sheath and the radar signal under a large bandwidth system. This invention models the multi-domain characteristics of the broadband radar echo of a target covered by a plasma sheath, highlighting the influence of the wide parametric nature of the radar signal on the multi-domain characteristics of the echo of the target covered by a plasma sheath, filling the gap in the modeling of the multi-domain characteristics of the broadband radar echo of a target covered by a plasma sheath, and has the characteristics of low modeling difficulty and high modeling accuracy. Attached Figure Description

[0079] Figure 1 This is a flowchart of the method of the present invention.

[0080] Figure 2 This is an electron density distribution diagram of the ion sheath in this invention.

[0081] Figure 3 This is a schematic diagram showing the reference position of the ion sheath in this invention.

[0082] Figure 4 This is a simulation diagram of the one-dimensional range image of the broadband radar in this invention.

[0083] Figure 5 This is a two-dimensional time-frequency domain simulation diagram of the present invention. Detailed Implementation

[0084] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0085] See Figure 1 The method for constructing a multi-domain feature model of broadband radar echoes from targets covered by plasma sheaths includes the following steps:

[0086] Step 1, Solve for the characterization of the electromagnetic waves reflected by the plasma sheath broadband radar. ref (t): Input the layered electron density model of each plasma layer at the m-th reference position of the plasma sheath. e,n (m), unit charge e, electron mass m e Given the vacuum permittivity ε0, solve for the oscillation frequency f of the nth plasma layer. p,n (m); then solve for the diversity signal frequency f. i (m), where i is the carrier frequency sequence number of the diversity signal, i = 0, 1, 2, ..., I, and I represents the total number of diversity signals obtained after broadband electromagnetic wave frequency diversity processing; based on the flow field velocity v of each layer of the local plasma sheath. n (m), solve for the frequencies f of each diversity signal. i (m) Coupled Doppler frequency f d,i (m); The spatial distribution characteristics of the reflection coefficient of the broadband radar signal within the local plasma sheath and the complex reflection coefficient R at the target reference position. i,n (m), to obtain the amplitude attenuation and phase modulation information of the echo signal at each reference position of the target covered by the plasma sheath, and to solve the local plasma sheath broadband radar reflected electromagnetic wave characterization E by vector superposition. R (t,m); The local plasma sheath reflection coefficient, modulation phase, and intrapulse velocity coupling components all exhibit spatial distribution characteristics. The reflection coefficient distribution spectrum has typical peaks. Based on each reflection coefficient peak and the corresponding flow field velocity at each peak position, the broadband radar reflected electromagnetic wave E of the plasma sheath can be obtained. ref (t), the broadband radar-reflected electromagnetic wave of the entire plasma sheath is:

[0087]

[0088] Step 1 is as follows:

[0089] Step 1.1, calculate the termination frequency f of the broadband electromagnetic wave. end The specific formula is as follows:

[0090] f end =f c +B

[0091] In the formula, f c B represents the starting frequency of the broadband electromagnetic wave, and B represents the bandwidth of the broadband electromagnetic wave.

[0092] Step 1.2, input the unit charge e and electron mass m e And the vacuum permittivity ε0, based on the non-uniform plasma layering model at the m-th reference position, the electron density n of the n-th plasma layer. e,n (m), solve for the characteristic frequency f of the nth layer plasma at the mth reference position. p,n (m), the specific formula is:

[0093]

[0094] In the formula, m is the reference position number, m = 1, 2, ..., M, M is the total number of reference positions, e represents the input unit charge, and m e ε0 represents the electron mass, and ε0 represents the vacuum permittivity.

[0095] Step 1.3: Based on the different situations arising when broadband radar signals are incident on non-uniform plasma, obtain the diversity signal frequency f under different conditions. i (m):

[0096] (1) When the termination frequency of the incident broadband electromagnetic wave is less than the characteristic frequency of the outermost layer of the non-uniform plasma, i.e., f end <f p,1 When (m), broadband electromagnetic waves are reflected only in the outermost layer of the plasma;

[0097] (2) When the initial frequency of the incident broadband electromagnetic wave is greater than the peak characteristic frequency of the non-uniform plasma, i.e., f pmax (m)<f c At that time, broadband electromagnetic waves completely penetrate the non-uniform plasma, and are reflected at the surface of the spacecraft, i.e., transparent transmission occurs. pmax (m) represents the maximum characteristic frequency of the stratified plasma at the m-th reference position;

[0098] (3) When the frequency range of the incident broadband electromagnetic wave is f p,1 (m)<f c <f end <f pmaxWhen (m), the broadband electromagnetic wave is incident entirely into the non-uniform plasma, with different frequency components corresponding to different incident depths, according to f i (m)=f p,n (m) Design the diversity signal, where i is the carrier frequency sequence number of the diversity signal, i = 0, 1, 2, ..., I, and I represents the total number of diversity signals obtained after broadband electromagnetic wave frequency diversity processing, f I (m) represents the maximum diversity frequency obtained after broadband electromagnetic wave frequency diversity processing, f p,n (m) represents the characteristic frequency of the nth plasma layer, and the diversity signal frequency f. i This corresponds to the characteristic frequencies of each plasma layer within the intersection range of the broadband radar signal frequency range and the plasma characteristic frequency gradient.

[0099] (4) When the frequency range of the incident broadband electromagnetic wave is f c <f p,1 (m)<f end <f pmax When (m), a broadband electromagnetic wave component is incident into the non-uniform plasma. Different frequency components correspond to different incident depths, according to f i (m)=f p,n (m) Design diversity signals;

[0100] (5) When the frequency range of the incident broadband electromagnetic wave is f p,1 (m)<f c <f pmax (m)<f end When broadband electromagnetic waves are incident on the interior of a non-uniform plasma, some diversity signals penetrate the non-uniform plasma and are transmitted to the target surface, while simultaneously generating transparent transmission and electromagnetic shielding effects.

[0101] In cases (1) and (2), the frequency of the broadband radar signal does not affect the reflection result, so diversity processing is not required. In cases (3), (4), and (5), since plasma has the characteristic of intercepting electromagnetic waves smaller than the plasma's characteristic frequency, according to f i (m)=f p,n (m) Design diversity signal, f p,n (m) represents the characteristic frequency of the nth plasma layer, and the diversity signal frequency f. i (m) corresponds to the characteristic frequencies of each plasma layer within the intersection range of the broadband radar signal frequency range and the plasma characteristic frequency gradient.

[0102] Step 1.4, calculate the Doppler frequencies of the diversity signals coupled at the m-th reference position: input the flow field velocity v of each layer of the local plasma sheath. n Solve for the frequency f of each diversity signal. i (m) corresponds to the coupling Doppler frequency fd,i (m):

[0103]

[0104] In the formula, v n (m) represents the flow field velocity at the m-th reference position, f i (m) represents the frequency of the diversity signal at the m-th reference position;

[0105] Step 1.5: Solve for the broadband radar-reflected electromagnetic wave E of the nth layer of plasma in the local plasma sheath at the m-th reference position. R (t,n,m): Assuming the broadband echo signal can be divided into I diversity signals, based on the spatial distribution characteristics of the reflection coefficient of the broadband radar signal within the local plasma sheath, the broadband radar reflected electromagnetic wave of the nth layer of plasma in the local plasma sheath is solved by vector accumulation as shown below:

[0106]

[0107] In the formula, R i,n (m) represents the reflection coefficient of the i-th diversity signal at the n-th layer, |R i,n (m)| represents the amplitude modulation of the i-th diversity signal at the n-th layer. This represents the phase modulation of the i-th diversity signal in the n-th plasma layer;

[0108] Step 1.6, calculate the electromagnetic wave E reflected by the local plasma sheath under the large bandwidth system at the m-th reference position. R (t,m): Broadband radar-reflected electromagnetic wave E based on the nth layer plasma of the local plasma sheath. R (t,n,m) is used to obtain the electromagnetic wave reflected by the local plasma sheath under a large bandwidth regime, as shown below:

[0109]

[0110] Step 1.7: Perform vector superposition of the electromagnetic waves reflected by the local plasma sheath at M reference positions under the large bandwidth regime to obtain the broadband radar reflected electromagnetic wave E of the target covered by the plasma sheath. R (t):

[0111]

[0112] Step 1.8: Since the reflection coefficient, modulation phase, and intra-pulse velocity coupling components all have spatial distribution characteristics, the reflection coefficient distribution spectrum within the local plasma sheath exhibits typical peaks. Based on each peak and the corresponding flow field velocity at each peak location, the broadband radar-reflected electromagnetic wave E of the entire plasma sheath is obtained. ref (t) is as follows:

[0113]

[0114] In the formula, M is the total number of reference positions, Q is the number of peaks in the reflectance coefficient distribution spectrum at the m-th position, and R... q (m) represents the q-th peak reflectance at the m-th reference position, f q (m) represents the diversity signal frequency corresponding to the q-th peak position, f d,q (m) is the Doppler frequency generated by the velocity field of the layer where the diversity signal is coupled at the qth peak position, which is found after simulation.

[0115] This invention establishes a frequency domain diversity model for broadband radar signals, obtains the flow field velocity corresponding to the peak position after the vector superposition of each diversity signal incident on the plasma sheath, solves the Doppler frequency of the flow field velocity corresponding to the peak position, and establishes a broadband radar reflection electromagnetic wave model of the plasma sheath-encased target, providing a foundation for carrying out calculations of the broadband time domain echo model of the plasma sheath-encased target.

[0116] Step 2, calculate the broadband time-domain echo model Echo(t) of the target covered by the plasma sheath: input radar signal amplitude A, radar signal modulation frequency k, and radar signal pulse width T. P By utilizing the spatial distribution characteristics of the reflection coefficient of broadband radar signals within a local plasma sheath and a linear frequency modulated pulse signal model, and based on the broadband electromagnetic reflection mechanism of a target encased in a plasma sheath, combined with a multi-reference position geometric model, and using numerical calculations of the plasma sheath flow field under typical flight conditions, the broadband time-domain echo Echo(t) of a target encased in a plasma sheath under a broadband linear frequency modulated system is obtained. The expression for the broadband time-domain echo of a target encased in a plasma sheath under a broadband linear frequency modulated system is as follows:

[0117]

[0118] Step 2 is as follows:

[0119] Step 2.1, Input linear frequency modulated pulse radar signal s(t): Input radar signal amplitude A, radar signal modulation frequency k, and broadband radar signal pulse width T. P Given the noise signal n(t), determine the linear frequency modulated pulse signal radar model s(t):

[0120]

[0121] In the formula, A represents the amplitude of the radar signal, k represents the frequency modulation frequency of the radar signal, and T... p The pulse width of the broadband radar signal is represented by n(t), and the noise signal is represented by n(t).

[0122] Step 2.2, Solve the local broadband time-domain echo model of the target covered by the plasma sheath: Model the broadband time-domain echo model of the target covered by the plasma sheath at the m-th reference position to obtain the local broadband time-domain echo model Echo(t,m) of the target covered by the plasma sheath at the m-th reference position. The specific model is as follows:

[0123]

[0124] In the formula, k represents the modulation frequency, and T p,q (m) represents the pulse width of the diversity signal corresponding to the q-th peak position, r m f represents the m-th reference position of the target covered by the plasma sheath. d,q (m) represents the coupled Doppler frequency corresponding to the diversity signal frequency at the q-th peak position;

[0125] Step 2.3: The reflection coefficient, modulation phase, and intra-pulse velocity coupling components have spatial distribution characteristics. The reflection coefficient distribution spectrum within the local plasma sheath exhibits typical peaks, with peak positions located at different plasma layer numbers. Therefore, the pulse width T of the diversity signal corresponding to the m-th reference position and the q-th peak position is... p,q The solution method for (m) is as follows:

[0126] Step 2.3.1: Let x be the number of local plasma sheath layers corresponding to the q-th peak at the m-th reference position, where x = 0, 1, 2, ..., N. Calculate the characteristic frequency difference Δf between two adjacent plasma layers. p,x (m):

[0127] Δf p,x (m)=f p,x+1 (m)-f p,x (m)

[0128] In the formula, f p,x (m) represents the characteristic frequency of the x-th layer plasma at the m-th reference position, f p,x+1 (m) represents the characteristic frequency of the plasma in the (x+1)th layer at the m-th reference position, Δf p,x (m) represents the characteristic frequency difference between two adjacent plasma layers;

[0129] Step 2.3.2: Solve for the pulse width T of the diversity signal corresponding to the q-th peak position. p,q (m):

[0130]

[0131] In the formula, k represents the frequency modulation frequency of the radar signal;

[0132] Step 2.4, Calculate the broadband time-domain echo model of the target covered by the plasma sheath: Perform vector superposition of the broadband time-domain echo models of the M reference positions of the plasma sheath to obtain the broadband time-domain echo model Echo(t) of the target covered by the plasma sheath. The specific model is as follows:

[0133]

[0134] In the formula, k represents the frequency modulation frequency of the radar signal, and T p,q (m) represents the pulse width of the diversity signal corresponding to the q-th peak position, r m f represents the m-th reference position of the target covered by the plasma sheath. d,q (m) represents the coupled Doppler frequency corresponding to the diversity signal frequency at the q-th peak position;

[0135] This invention is based on a broadband radar reflection electromagnetic wave model of a target covered by a plasma sheath, and solves the expression of the echo signal of the target covered by the plasma sheath. This provides model support for extracting multi-domain features of the echo signal and revealing the mechanism of peak broadening of the one-dimensional range image.

[0136] Step 3: Establish a multi-domain characteristic model of the broadband time-domain echo of the target covered by a plasma sheath: Based on the pulse compression processing of the broadband time-domain echo model Echo(t) of the target covered by a plasma sheath, obtain a one-dimensional range image analysis model of the broadband radar; perform characteristic analysis in the time-frequency domain using the Wegener transform method to obtain a two-dimensional time-frequency domain analysis model; perform characteristic analysis in the time-delay-Doppler domain using fuzzy functions to obtain a two-dimensional time-delay-Doppler domain analysis model, and study the influence of the plasma sheath on the radar signal;

[0137] The specific process of establishing a broadband radar one-dimensional range image analysis model is as follows:

[0138] (1) Design the matched filter h(t): based on the pulse width T of the diversity signal corresponding to the qth peak position. p,q (m), the diversity signal frequency f corresponding to the qth peak position q (m) Frequency modulation (k), combined with the form of a linear frequency modulated signal, the matched filter is set as follows:

[0139]

[0140] (2) Based on pulse compression processing, a matched filter is used to perform pulse compression processing on the radar echo signal Echo(t) to obtain a broadband radar echo range domain characterization of the plasma sheath-encased target:

[0141]

[0142]

[0143] In the formula, k represents the frequency modulation frequency of the radar signal, and r m T represents the m-th reference position of the target covered by the plasma sheath. p f represents the pulse width of a broadband radar signal. q (m) represents the diversity signal frequency corresponding to the qth peak position;

[0144] As can be seen from the above equation, the peak position of the sa function is affected by f. q The influence of (m) means that the Doppler frequency corresponding to the coupling velocity at different depths at each reference position will affect the peak position on the one-dimensional range image.

[0145] The specific process of establishing the two-dimensional time-frequency domain analysis model is as follows: Based on the Wegener transform, the two-dimensional time-frequency of the broadband radar echo of the plasma sheath-covered target is solved, and characterized as follows:

[0146]

[0147] In the formula, P echo =A 2 ×R q (m) 2 The term represents the time-frequency amplitude of the modulated broadband radar signal after the Wegener transform, τ represents the delay when the echo signal is autocorrelated, and ct is the sum of all outputs including cross terms and noise terms after the Wegener transform. In the field of radar signal processing technology, δ(t) is the expression of the unit impulse function, and the peak position of the impulse function contains the intra-pulse velocity information of the broadband echo signal coupling.

[0148] The specific process of establishing the two-dimensional time delay-Doppler domain analysis model is as follows: Based on the fuzzy function, the two-dimensional time delay-Doppler frequency of the broadband radar echo of the plasma sheath-covered target is solved, and characterized as follows:

[0149]

[0150] In the formula, τ m ξ represents the time delay, and ξ represents the frequency offset (intra-pulse Doppler frequency). When the fuzzy function processing result is the maximum value, the frequency offset ξ is a series of straight lines related to the intra-pulse coupling velocity and the position of each reference position.

[0151] This invention extracts peak intervals and peak broadening between different domains through Wegener transform, providing a research basis for quantitatively studying the influence of different flight altitudes, speeds, carrier frequencies, pulse widths, and bandwidths on the characteristics of broadband radar echoes in different domains.

[0152] See Figure 2As shown in the figure, the plasma sheath thickness and electron density distribution vary greatly at different locations. The plasma sheath thickness gradually increases from the stagnation point to the tail end, while the peak electron density gradually decreases.

[0153] See Figure 3 ,Depend on Figure 2 It is known that the thickness and electron density distribution of the plasma sheath vary greatly at different locations. When conducting an overall study of the target covered by the plasma sheath, it is necessary to consider the differences between each location and conduct separate analyses to reflect the differences in characteristics between different locations of the target covered by the plasma sheath.

[0154] See Figure 4 As shown in the figure, the broadband radar echo signal contains multiple intra-pulse Doppler frequencies, which causes multiple mismatches in the matched filter, resulting in multiple peaks in the range dimension. This reflects the influence of the large frequency domain span of the broadband radar signal on the one-dimensional range image of the local reference position of the plasma sheath.

[0155] See Figure 5 As shown in the figure, there are multiple sloping straight lines in the time-frequency domain of the broadband radar echo signal, indicating that the echo is coupled with multiple Doppler frequencies. This reflects the influence of the large frequency domain span of the broadband radar signal on the time-frequency analysis of the plasma sheath echo at the local reference position.

[0156] A system for constructing a multi-domain feature model of broadband radar echoes from targets covered by plasma sheaths includes:

[0157] Plasma sheath broadband radar reflected electromagnetic wave modeling module: used to calculate the electromagnetic wave E reflected by plasma sheath broadband radar. ref (t), this module corresponds to step 1;

[0158] Plasma sheath-encased target broadband time-domain echo modeling module: Utilizing the broadband radar reflection of electromagnetic waves E by the plasma sheath ref (t), establish the broadband time-domain echo model Echo(t) of the target covered by the plasma sheath, which corresponds to step 2;

[0159] Multi-domain feature modeling module for broadband radar echo of plasma sheath-encased target: Using the broadband time-domain echo model Echo(t) of plasma sheath-encased target, a multi-domain feature model of broadband radar echo of plasma sheath-encased target is established. This module corresponds to step 3.

[0160] The equipment for constructing a multi-domain feature model of broadband radar echoes from targets encased in plasma sheaths includes:

[0161] Memory: Used to store the computer program that implements the method for constructing the multi-domain feature model of the broadband radar echo of the plasma sheath-encased target;

[0162] A processor is used to implement the method for constructing the multi-domain feature model of the broadband radar echo of the plasma sheath-encased target when executing the computer program.

[0163] A computer-readable storage medium comprising:

[0164] The computer-readable storage medium stores a computer program that, when executed by a processor, enables a method for constructing a multi-domain feature model of a broadband radar echo of a target covered by a plasma sheath.

Claims

1. A method for constructing a multi-domain feature model of broadband radar echoes from targets covered by plasma sheaths, characterized in that, Includes the following steps: Step 1: Calculate the electromagnetic wave E reflected by the broadband radar from the plasma sheath. ref (t); Step 1 calculates the broadband radar reflected electromagnetic wave E from the plasma sheath. ref The specific process of (t) is as follows: Step 1.1, calculate the termination frequency f of the broadband electromagnetic wave. end The specific formula is as follows: f end =f c +B In the formula, f c B represents the starting frequency of the broadband electromagnetic wave, and B represents the bandwidth of the broadband electromagnetic wave. Step 1.2: Using the non-uniform plasma layering model at the m-th reference position, the electron density n of the n-th plasma layer is determined. e,n (m), calculate the characteristic frequency f of the nth layer plasma at the mth reference position. p,n (m), the specific formula is: In the formula, m is the reference position number, m = 1, 2, ..., M, M is the total number of reference positions, e represents the input unit charge, and m e ε0 represents the electron mass, and ε0 represents the vacuum permittivity. Step 1.3, using the broadband electromagnetic wave termination frequency f obtained in Step 1.1 end The characteristic frequency f of the nth layer plasma at the mth reference position obtained in step 1.2 p,n (m), based on different situations when broadband radar signals are incident on non-uniform plasma, the diversity signal frequency f under different conditions is obtained. i (m); Step 1.4, using the diversity signal frequency f obtained in step 1.3 i (m), calculate the frequency f of each diversity signal at the m-th reference position. i (m) corresponds to the coupling Doppler frequency f d,i (m), the specific formula is: In the formula, v n (m) represents the flow field velocity at the m-th reference position, f i (m) represents the frequency of the diversity signal at the m-th reference position; Step 1.5, using the coupling Doppler frequency f obtained in step 1.4 d,i (m), calculate the broadband radar-reflected electromagnetic wave E of the nth layer of plasma in the local plasma sheath at the m-th reference position. R (t,n,m): Assuming the broadband echo signal can be divided into I diversity signals, based on the spatial distribution characteristics of the reflection coefficient of the broadband radar signal within the local plasma sheath, the broadband radar reflected electromagnetic wave E of the nth layer of plasma in the local plasma sheath is solved by vector accumulation. R (t,n,m), the specific formula is: In the formula, R i,n (m) represents the reflection coefficient of the i-th diversity signal at the n-th layer, |R i,n (m)| represents the amplitude modulation of the i-th diversity signal at the n-th layer. This represents the phase modulation of the i-th diversity signal in the n-th plasma layer; Step 1.6: Utilize the broadband radar-reflected electromagnetic wave E of the nth layer plasma of the local plasma sheath obtained in Step 1.

5. R (t,n,m), calculate the electromagnetic wave E reflected by the local plasma sheath under the large bandwidth system at the m-th reference position. R (t,m), the specific formula is: Step 1.7, based on the electromagnetic wave E reflected by the local plasma sheath under the large bandwidth system at the m-th reference position obtained in Step 1.

6. R (t,m) represents the vector superposition of locally reflected electromagnetic waves from the plasma sheath at M reference positions under a large bandwidth regime, yielding the broadband radar reflected electromagnetic wave E of the target enveloped by the plasma sheath. R (t), the specific formula is: Step 1.8, based on the plasma sheath coating of the target broadband radar reflected electromagnetic wave E obtained in Step 1.

7. R (t) and the typical peak values ​​of the local plasma sheath reflection coefficient distribution spectrum and the corresponding flow field velocities at each peak position are used to calculate the broadband radar reflected electromagnetic wave E of the plasma sheath. ref (t): In the formula, M represents the total number of reference positions, Q represents the number of peaks in the reflectance coefficient distribution spectrum at the m-th position, and R... q (m) represents the q-th peak reflectance at the m-th reference position, f q (m) represents the diversity signal frequency corresponding to the q-th peak position, f d,q (m) represents the Doppler frequency generated by the velocity field of the layer where the diversity signal is coupled at the qth peak position, which is found after simulation. Step 2: Based on the broadband radar reflected electromagnetic wave E obtained in Step 1, ref (t), establish a broadband time-domain echo model Echo(t) for the target covered by a plasma sheath; Step 3: Based on the broadband time-domain echo model Echo(t) of the plasma sheath-covered target obtained in Step 2, establish a multi-domain feature model of the broadband radar echo of the plasma sheath-covered target.

2. The method for constructing a multi-domain feature model of a broadband radar echo of a target covered by a plasma sheath according to claim 1, characterized in that, The specific process of establishing the broadband time-domain echo model Echo(t) of the plasma sheath-encased target in step 2 is as follows: Step 2.1, determine the linear frequency modulated pulse signal radar model s(t), the specific model is as follows: In the formula, A represents the amplitude of the radar signal, k represents the frequency modulation frequency of the radar signal, and T... p The pulse width of the broadband radar signal is represented by n(t), and the noise signal is represented by n(t). Step 2.2, based on the electromagnetic wave E reflected by the local plasma sheath under the large bandwidth system at the m-th reference position obtained in Step 1.

6. R Using the linear frequency modulated pulse signal radar model s(t) obtained in step 2.1, a broadband time-domain echo model of the plasma sheath at the m-th reference position is modeled, resulting in the local broadband time-domain echo model Echo(t,m) of the plasma sheath-covered target at the m-th reference position. The specific model is as follows: In the formula, k represents the frequency modulation frequency of the radar signal, and T p,q (m) represents the pulse width of the diversity signal corresponding to the q-th peak position, r m f represents the m-th reference position of the target covered by the plasma sheath. d,q (m) represents the coupled Doppler frequency corresponding to the diversity signal frequency at the q-th peak position; Step 2.3: Calculate the pulse width T of the diversity signal corresponding to the qth peak position at the m-th reference position in the local plasma sheath reflection coefficient distribution spectrum. p,q (m); Step 2.4, using the pulse width T obtained in step 2.3 p,q The local broadband time-domain echo model Echo(t,m) obtained in step 2.2 is vector-superimposed on the local broadband time-domain echo models of the plasma sheath at M reference positions to obtain the broadband time-domain echo model Echo(t) of the plasma sheath-enclosed target. The specific model is as follows:

3. The method for constructing a multi-domain feature model of a broadband radar echo of a target covered by a plasma sheath according to claim 1, characterized in that, The broadband time-domain echo multi-domain feature model of the target covered by the plasma sheath in step 3 includes a broadband radar one-dimensional range image analysis model, a two-dimensional time-frequency domain analysis model, and a two-dimensional time-delay-Doppler domain analysis model: The broadband radar one-dimensional range profile analysis model is specifically as follows: Based on pulse compression processing, a broadband radar echo range domain characterization of a plasma sheath-encased target is obtained: The specific two-dimensional time-frequency domain analysis model is as follows: Based on the Wegener transform, the two-dimensional time-frequency of the broadband radar echo of the plasma sheath-covered target is solved, and characterized as follows: In the formula, P echo =A 2 ×|R q (m)| 2 The term represents the time-frequency amplitude of the modulated broadband radar signal after the Wegener transform, ct is the sum of all outputs after the Wegener transform, including cross terms and noise terms, and the peak position of the impulse function contains the intra-pulse velocity information coupled with the broadband echo signal. The specific two-dimensional time delay-Doppler domain analysis model is as follows: Based on a fuzzy function, the two-dimensional time delay-Doppler frequency of the broadband radar echo from the plasma sheath-encased target is solved, and characterized as follows: In the formula, τ represents the time delay, and ξ represents the frequency offset, i.e. the intrapulse Doppler frequency. When the fuzzy function processing result is the maximum value, the frequency offset ξ is a series of straight lines related to the intrapulse coupling velocity and the position of each reference position.

4. The method for constructing a multi-domain feature model of a broadband radar echo of a target covered by a plasma sheath according to claim 1, characterized in that, In step 1.3, the diversity signal frequency f under different conditions is obtained based on the different situations when the broadband radar signal is incident on the non-uniform plasma. i (m), specifically: (1) When the termination frequency of the incident broadband electromagnetic wave is less than the characteristic frequency of the outermost layer of the non-uniform plasma, i.e., f end <f p,1 When (m), broadband electromagnetic waves are reflected only in the outermost layer of the plasma; (2) When the initial frequency of the incident broadband electromagnetic wave is greater than the peak characteristic frequency of the non-uniform plasma, i.e., f pmax (m)<f c At that time, broadband electromagnetic waves completely penetrate the non-uniform plasma, and the broadband electromagnetic waves are reflected on the surface of the aircraft, that is, transparent transmission is generated. (3) When the frequency range of the incident broadband electromagnetic wave is f p,1 (m)<f c <f end <f pmax When (m), the broadband electromagnetic wave is incident entirely into the non-uniform plasma, with different frequency components corresponding to different incident depths, according to f i (m)=f p,n (m) Design the diversity signal, where the diversity signal frequency f i (m) represents the characteristic frequencies of each plasma layer within the intersection range of the broadband radar signal frequency range and the plasma characteristic frequency gradient, f p,n (m) represents the characteristic frequency of the nth plasma layer, i represents the carrier frequency sequence number of the diversity signal, i = 0, 1, 2, ..., I, I represents the total number of diversity signals obtained after broadband electromagnetic wave frequency diversity processing, f I (m) represents the maximum diversity frequency obtained after broadband electromagnetic wave frequency diversity processing; (4) When the frequency range of the incident broadband electromagnetic wave is f c <f p,1 (m)<f end <f pmax When (m), a broadband electromagnetic wave component is incident into the non-uniform plasma. Different frequency components correspond to different incident depths, according to f i (m)=f p,n (m) Design diversity signals; (5) When the frequency range of the incident broadband electromagnetic wave is f p,1 (m)<f c <f pmax (m)<f end When broadband electromagnetic waves are incident on the interior of a non-uniform plasma, some diversity signals penetrate the non-uniform plasma and are transmitted to the target surface, resulting in transparent transmission and electromagnetic shielding effects.

5. The method for constructing a multi-domain feature model of a broadband radar echo of a target covered by a plasma sheath according to claim 2, characterized in that, In step 2.3, the pulse width T of the diversity signal corresponding to the m-th reference position and the q-th peak position in the local plasma sheath reflection coefficient distribution spectrum is... p,q The solution method for (m) is as follows: Step 2.3.1, let x be the number of local plasma sheath layers corresponding to the q-th peak at the m-th reference position, where x = 0, 1, 2, ..., N. Then the characteristic frequency difference Δf between two adjacent plasma layers is... p,x (m) is: Δf p,x (m)=f p,x+1 (m)-f p,x (m) In the formula, f p,x (m) represents the characteristic frequency of the x-th layer plasma at the m-th reference position, f p,x+1 (m) represents the characteristic frequency of the plasma in the (x+1)th layer at the m-th reference position, Δf p,x (m) represents the characteristic frequency difference between two adjacent plasma layers; Step 2.3.2, using the characteristic frequency difference Δf between two adjacent plasma layers obtained in step 2.3.

1. p,x (m), calculate the pulse width T of the diversity signal corresponding to the q-th peak position. p,q (m): In the formula, k represents the frequency modulation frequency of the radar signal, and f p,x (m) represents the characteristic frequency of the x-th layer plasma at the m-th reference position, f p,x+1 (m) represents the characteristic frequency of the plasma in the (x+1)th layer at the m-th reference position, Δf p,x (m) represents the characteristic frequency difference between two adjacent plasma layers.

6. A system for constructing a multi-domain feature model of a broadband radar echo of a target covered by a plasma sheath based on the method of claim 1, characterized in that, include: Plasma sheath broadband radar reflected electromagnetic wave modeling module: used to calculate the electromagnetic wave E reflected by plasma sheath broadband radar. ref (t); Plasma sheath-encased target broadband time-domain echo modeling module: Utilizing the broadband radar reflection of electromagnetic waves E by the plasma sheath ref (t), establish a broadband time-domain echo model Echo(t) for the target covered by a plasma sheath; Multi-domain feature modeling module for broadband radar echo of plasma sheath-encased target: Using the broadband time-domain echo model Echo(t) of plasma sheath-encased target, a multi-domain feature model of broadband radar echo of plasma sheath-encased target is established.

7. A device for constructing a multi-domain feature model of broadband radar echo of a target covered by a plasma sheath, characterized in that, include: Memory: A computer program for storing the method for constructing the multi-domain feature model of the broadband radar echo of the plasma sheath-encased target according to any one of claims 1-5; A processor, configured to implement, when executing the computer program, the method for constructing a multi-domain feature model of a broadband radar echo of a target covered by a plasma sheath, as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, include: The computer-readable storage medium stores a computer program that, when executed by a processor, enables the construction method of the multi-domain feature model of the broadband radar echo of the target covered by a plasma sheath, as described in any one of claims 1-5.

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