CN114966575A - Method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering - Google Patents
Method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering Download PDFInfo
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Abstract
The invention relates to the technical field of target electromagnetic scattering and acoustic scattering, and discloses a method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering, which comprises the following steps: 1) determining the electromagnetic scattering frequency of a three-dimensional target to be evaluated; 2) determining a three-dimensional target which evaluates the acoustic wave frequency, the acoustic signal pulse width, the sweep frequency bandwidth and the corresponding acoustic properties of acoustic scattering test in electromagnetic scattering through the acoustic scattering of the three-dimensional target; 3) and the three-dimensional target corresponds to the acoustic property and is arranged in the silencing water pool for testing. The method for evaluating the electromagnetic scattering characteristics through the three-dimensional target acoustic scattering comprises the steps of installing a target required by acoustic scattering testing in an underwater acoustic compact range or a conventional water pool to carry out acoustic scattering testing on the target at different angles, collecting and storing acoustic scattering echo signals at different angles, and finally processing the acoustic scattering echo signals by adopting amplitude calculation, pulse compression and an R-D two-dimensional imaging algorithm to obtain a target electromagnetic scattering characteristic result.
Description
Technical Field
The invention relates to the technical field of target electromagnetic scattering and acoustic scattering, in particular to a method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering.
Background
The electromagnetic scattering is electromagnetic waves which are radiated secondarily after induced current is formed on the surface of a target body by incident electromagnetic waves, the scattered electromagnetic waves contain information characteristics of the target and are carriers of target information, the electromagnetic scattering characteristics of the target can be further obtained on the basis of the scattered electromagnetic waves, and the electromagnetic scattering characteristics of the target have important significance in radar detection, stealth design and electronic countermeasure, and especially have indispensable effect in modern radar automatic target identification.
At present, actual tests of target electromagnetic scattering characteristics mainly include a microwave darkroom method, a compact field test method and an external field test method, although the accuracy of the actual tests is high, the test cost is high, the technical difficulty is high, and the requirements on the test environment are high.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering, which has the advantages of higher detection result precision and the like, and solves the problems of higher actual test cost, high technical difficulty and higher requirement on test environment of the target electromagnetic scattering characteristics in the prior art.
(II) technical scheme
In order to achieve the purpose, the invention provides the following technical scheme: a method for assessing electromagnetic scattering characteristics through three-dimensional target acoustic scattering, comprising the steps of:
1) determining the electromagnetic scattering frequency, the corresponding electromagnetic wave frequency, the pulse width, the sweep frequency bandwidth and the three-dimensional target property of the three-dimensional target to be evaluated, and taking the scaling coefficient r 1 ；
2) Determining a three-dimensional target which evaluates the acoustic wave frequency, the acoustic signal pulse width, the sweep frequency bandwidth and the corresponding acoustic properties of acoustic scattering test in electromagnetic scattering through the acoustic scattering of the three-dimensional target;
3) the three-dimensional target corresponding to the acoustic property is arranged in the silencing water pool for testing;
4) when a result of evaluating single-station electromagnetic scattering of a target through three-dimensional target acoustic scattering needs to be obtained, performing single-frequency point acoustic scattering test, and continuing to operate, and when a one-dimensional distance image of the target through three-dimensional target acoustic scattering evaluation and an ISAR result need to be obtained, performing linear frequency sweep acoustic scattering test with a certain bandwidth;
5) the three-dimensional target acoustic scattering single angle test process comprises the steps that a signal source generates a transmitting signal, the signal is transmitted after being amplified, an echo signal scattered by a target is received, and the echo signal is linearly amplified, filtered and stored;
6) according to the step 4, completing the acoustic scattering test of the three-dimensional target in different angle ranges with the required stepping angle;
7) if the single-frequency point acoustic scattering exists, intercepting a target acoustic scattering signal from the acquired callback signal at each angle, and performing FFT (fast Fourier transform algorithm) calculation to obtain a single-station acoustic scattering test result of the three-dimensional target, wherein the result is a result of evaluating single-station electromagnetic scattering of the target through the three-dimensional target acoustic scattering;
8) carrying out pulse compression processing on the acquired callback signals at a single angle to obtain a one-dimensional range profile result of the corresponding angle of the target to be detected, wherein the result is a result of evaluating the electromagnetic scattering one-dimensional range profile of the target through acoustic scattering of the target;
9) and (4) processing the multi-angle scattering echo signals collected in the step (6) by adopting an R-D algorithm to obtain an ISAR imaging result of the target, wherein the result is a result of evaluating electromagnetic scattering two-dimensional imaging of the target through acoustic scattering of the target.
Further, the method for determining the three-dimensional target with the acoustic frequency, the acoustic signal pulse width, the sweep frequency bandwidth and the corresponding acoustic properties of the acoustic scattering test in the electromagnetic scattering evaluation by the acoustic scattering of the three-dimensional target in the step 2) comprises the following steps:
a. when the target is a conductor, the target corresponding to the acoustic test is a rigid graph or an absolute elastic body, and the volume scale is reduced by r 1 Doubling;
b. when the target is a dielectric body, the reflection coefficient of the electromagnetic wave corresponding to the dielectric body is V 1 The material to be tested should be a common elastomer, and its acoustic reflection coefficient must be V 1 While simultaneously reducing the volume scale r 1 Doubling;
c. when the frequency of the electromagnetic wave to be evaluated is (f) e1 -f e2 )(GHz), pulse time T e1 When the frequency of the corresponding sound wave is (f) s1 -f s2 ) (KHz) with a sonic pulse time of T s1 ＝2·10 5 ·T e1 /r 1 Wherein, f s1 ＝5·r 1 ·f e1 ，f s2 ＝5·r 1 ·f e2 When f is e1 ＝f e2 When d is greater than s1 ＝f s2 The test is a single frequency point test.
Further, in the step 7), the test signal acquired at each angle is processed by using a fourier transform method, and S (m, f) ═ FFT n (s r (m, t)), then the amplitude value of the corresponding frequency is intercepted and subjected to amplitude normalization processing, and the single-station acoustic scattering value R (m.DELTA.theta) corresponding to the angle m.DELTA.theta can be obtained as normal (S (m, f) 1 ) And circularly calculating the R (m.delta theta) values of all angles to obtain the calculation result of the target single-station electromagnetic scattering of the target acoustic scattering test evaluation.
Further, the specific method for calculating the one-dimensional range profile of the target by using the pulse compression algorithm in the step 8) is as follows: performing matched filtering processing on the acquired test signal, wherein y (t) IFFT (S (f) H (f) wins), namely the calculation result of the target acoustic scattering evaluation target electromagnetic scattering one-dimensional range profile, wherein S (f) is a received signal s r (t) Fourier transform S (f) FFT(s) r (t))，H(f)＝conj(FFT(s t (t))) is the system's corresponding function s of the transmitted signal t And (t) corresponding functions of the system, namely FFT (-), IFFT (-), and conj (-), are fast Fourier transform, inverse Fourier transform and complex conjugate calculation respectively, and wins is a Hamming window function.
Further, in the step (nine), an R-D algorithm is used as a target electromagnetic scattering two-dimensional imaging calculation method, that is, two-dimensional fourier transform is performed on the distance and the direction respectively, and it is assumed that the originally received measurement data is s r (m, n), where m is the azimuth sampling angle number, n is the distance image sampling number of the time domain, IFFT processing is performed in the distance direction to obtain target distance data IFFT in different azimuths n (s r (m, n)); then FFT processing is carried out in the azimuth direction, and the FFT of the two-dimensional imaging result of the target can be obtained m (IFFT n (s r (m, n))), namely, the target acoustic scattering evaluates the target electromagnetic scattering two-dimensional imaging result.
(III) advantageous effects
Compared with the prior art, the invention provides a method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering, which has the following beneficial effects:
1. the method for evaluating the electromagnetic scattering characteristics through the three-dimensional target acoustic scattering comprises the steps of determining the electromagnetic scattering frequency of a three-dimensional target to be evaluated and the properties of a target medium, then determining the acoustic signal frequency, the pulse width, the sweep frequency width, the properties, the size and the volume of the target and the like required by a target acoustic scattering test according to a scaling relation, then installing the target required by the acoustic scattering test in an underwater acoustic compact field or a conventional water pool to perform the acoustic scattering test of the target at different angles, collecting and storing acoustic scattering echo signals at different angles, and finally processing the acoustic scattering echo signals by adopting amplitude calculation, pulse compression and an R-D two-dimensional imaging algorithm to obtain a target electromagnetic scattering characteristic result.
2. The method for evaluating the electromagnetic scattering characteristics through the three-dimensional target acoustic scattering evaluates the electromagnetic scattering characteristics of the target through simulation and test of the target acoustic scattering characteristics, and the target electromagnetic scattering characteristics comprise: the method is suitable for general underwater acoustic test and underwater acoustic compact field test, can correspond to general point-to-point microwave darkroom and microwave compact field test work in an electromagnetic environment, can effectively reduce the cost and technical difficulty of target electromagnetic scattering characteristic test and expand the technical method of target electromagnetic scattering characteristic evaluation, and inverts the electromagnetic scattering characteristic with higher frequency by using the acoustic scattering characteristic with lower frequency.
Drawings
FIG. 1 is a flow chart of a method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering according to the present invention;
FIG. 2 is a block diagram of a target acoustic scattering test flow of a method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering according to the present invention;
FIG. 3 is a schematic diagram of the measured object in the electromagnetic scattering evaluation according to the method for evaluating electromagnetic scattering characteristics by three-dimensional target acoustic scattering provided by the present invention;
FIG. 4 is a schematic diagram of a received waveform of an acoustic scattering characteristic test according to a method for evaluating electromagnetic scattering characteristics by three-dimensional target acoustic scattering according to the present invention;
FIG. 5 is a schematic diagram of an acoustic scattering signal extraction result of an acoustic scattering characteristic test according to a method for evaluating electromagnetic scattering characteristics by three-dimensional target acoustic scattering provided by the present invention;
fig. 6 is a schematic diagram of a target acoustic scattering test evaluation target single-station electromagnetic scattering result according to the method for evaluating electromagnetic scattering characteristics through three-dimensional target acoustic scattering provided by the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The acoustic wave is a longitudinal wave, like electromagnetic scattering, acoustic scattering also comprises information of size, structure, shape, material and the like of a target object, various information of the target object can be obtained through acoustic scattering measurement of the target object, acoustic scattering is the basis of various acoustic theory research and acoustic detection application technologies, although the electromagnetic wave and the acoustic wave are two waves with completely different properties, comparison of a wave equation, boundary conditions and the like of the two waves shows that the two waves have approximate expression forms under certain conditions, and based on the similarity, common application of some theories and technologies in the fields of crossing the electromagnetic wave and the acoustic wave is widely available, such as a metamaterial technology, a phased array and multi-beam technology, a scattering theory, an imaging technology and the like, and a partial theoretical basis is provided for an acoustic scattering evaluation method of electromagnetic scattering characteristics of the target object.
Referring to fig. 1-6, a method for evaluating electromagnetic scattering characteristics by three-dimensional target acoustic scattering includes the following steps:
1) determining the electromagnetic scattering frequency, the corresponding electromagnetic wave frequency, the pulse width, the sweep frequency bandwidth and the three-dimensional target property of the three-dimensional target to be evaluated, and taking the scaling coefficient r 1 ；
2) Determining a three-dimensional target which evaluates the acoustic wave frequency, the acoustic signal pulse width, the sweep frequency bandwidth and the corresponding acoustic properties of acoustic scattering test in electromagnetic scattering through the acoustic scattering of the three-dimensional target;
3) the three-dimensional target corresponding to the acoustic property is arranged in the silencing water pool for testing;
4) when a result of evaluating single-station electromagnetic scattering of a target through three-dimensional target acoustic scattering needs to be obtained, performing single-frequency point acoustic scattering test, and continuing to operate, and when a one-dimensional distance image of the target through three-dimensional target acoustic scattering evaluation and an ISAR result need to be obtained, performing linear frequency sweep acoustic scattering test with a certain bandwidth;
5) the three-dimensional target acoustic scattering single angle test process comprises the steps that a signal source generates a transmitting signal, the signal is transmitted after being amplified, an echo signal scattered by a target is received, and the echo signal is linearly amplified, filtered and stored;
6) according to the step 4, completing the acoustic scattering test of the three-dimensional target in different angle ranges with the required stepping angle;
7) if the single-frequency point acoustic scattering exists, intercepting a target acoustic scattering signal from the acquired callback signal at each angle, and performing FFT (fast Fourier transform algorithm) calculation to obtain a single-station acoustic scattering test result of the three-dimensional target, wherein the result is a result of evaluating single-station electromagnetic scattering of the target through the three-dimensional target acoustic scattering;
8) carrying out pulse compression processing on the acquired callback signals at a single angle to obtain a one-dimensional range profile result of the corresponding angle of the target to be detected, wherein the result is a result of evaluating the electromagnetic scattering one-dimensional range profile of the target through target acoustic scattering;
9) and (4) processing the multi-angle scattering echo signals collected in the step (6) by adopting an R-D algorithm to obtain an ISAR imaging result of the target, wherein the result is a result of evaluating the electromagnetic scattering two-dimensional imaging of the target through the acoustic scattering of the target.
It should be noted that, the method for determining the three-dimensional target of the acoustic frequency, the acoustic signal pulse width, the sweep frequency bandwidth and the corresponding acoustic properties of the acoustic scattering test in the electromagnetic scattering evaluation by the three-dimensional target acoustic scattering in the step 2) is as follows:
a. when the target is a conductor, the target corresponding to the acoustic test is a rigid graph or an absolute elastic body, and the volume scale is reduced by r 1 Doubling;
b. when the target is a dielectric body, the reflection coefficient of the electromagnetic wave corresponding to the dielectric body is V 1 The material to be tested should be a common elastomer, and its acoustic reflection coefficient must be V 1 While simultaneously reducing the volume scale r 1 Doubling;
c. when the frequency of the electromagnetic wave to be evaluated is (f) e1 -f e2 ) (GHz) pulse time T e1 When the frequency of the corresponding sound wave is (f) s1 -f s2 ) (KHz) with a sonic pulse time of T s1 ＝2·10 5 ·T e1 /r 1 Wherein f is s1 ＝5·r 1 ·f e1 ，f s2 ＝5·r 1 ·f e2 When f is e1 ＝f e2 When f is turned on s1 ＝f s2 The test is a single frequency point test.
Meanwhile, in step 7), the test signal acquired at each angle is processed by using a fourier transform method, and S (m, f) ═ FFT n (s r (m, t)), then intercepting the amplitude value corresponding to the frequency and carrying out amplitude normalization processing, so as to obtain the single-station sound scattering value R (m.delta theta) corresponding to the angle m.delta theta as normal (S (m, f) 1 ) And circularly calculating the R (m.delta theta) values of all angles to obtain the calculation result of the target single-station electromagnetic scattering of the target acoustic scattering test evaluation.
In step 8), calculating the target one-dimensional distance by using a pulse compression algorithmThe specific method of separating the image is as follows: performing matched filtering processing on the acquired test signal, wherein y (t) IFFT (S (f) H (f) wins), namely the calculation result of the target acoustic scattering evaluation target electromagnetic scattering one-dimensional range profile, wherein S (f) is a received signal s r (t) Fourier transform S (f) FFT(s) r (t))，H(f)＝conj(FFT(s t (t))) is the system-dependent function s of the transmitted signal t And (t) corresponding functions of the system, namely FFT (-), IFFT (-), and conj (-), are fast Fourier transform, inverse Fourier transform and complex conjugate calculation respectively, and wins is a Hamming window function.
It should be noted that, in step (nine), an R-D algorithm is used as a target electromagnetic scattering two-dimensional imaging calculation method, that is, two-dimensional fourier transform is performed on the distance and the direction, respectively, and it is assumed that originally received measurement data is s r (m, n), where m is the azimuth sampling angle number, n is the distance image sampling number of the time domain, IFFT processing is performed in the distance direction to obtain target distance data IFFT in different azimuths n (s r (m, n)); then FFT processing is carried out in the azimuth direction, and the FFT of the two-dimensional imaging result of the target can be obtained m (IFFT n (s r (m, n))), namely, the target acoustic scattering evaluates the target electromagnetic scattering two-dimensional imaging result.
In this embodiment, the electromagnetic scattering characteristics of the finite long cylinder are evaluated by using the acoustic scattering characteristics of the finite long cylinder, wherein the finite long cylinder is an acoustic soft body and an electromagnetic metal conductor, and when the finite long cylinder is subjected to an electromagnetic scattering test, the finite long cylinder is covered with an aluminum foil to realize the metal condition, and based on the scattering correspondence criterion, the frequency of an electromagnetic wave is selected to be 4GHz, the wavelength of a sound wave is selected to be 20KHz, and the wavelength of the corresponding electromagnetic wave and the wavelength of the sound wave are selected to be 75 mm.
In the target electromagnetic scattering characteristic evaluation by the target acoustic scattering test, corresponding target and sound wave parameters including target volume size, sound wave frequency, sweep frequency bandwidth and pulse width need to be determined.
It should be noted that when the size of the target dimension is not changed, the scaling factor r is taken 1 When the frequency of the electromagnetic wave to be evaluated is (f) 1 e1 -f e2 ) (GHz) pulse time T e1 When the frequency of the corresponding sound wave is (f) s1 -f s2 ) (KHz) with a sonic pulse time of T s1 ＝2·10 5 ·T e1 / r1 。
Wherein f is s1 ＝5·r 1 ·f e1 ，f s2 ＝5·r 1 ·f e2 When f is e1 ＝f e2 When f is present s1 ＝f s2 For single frequency point test, because the problem of single frequency point scattering in this embodiment is known from the above formula, the frequency of the corresponding sound wave in the test is 20KHz, and the wavelength of the corresponding sound wave is 75mm, for example, fig. 4 and 5 are graphs of the extraction results of the received waveform and the scattering signal in the target sound scattering characteristic test
It should be noted that the target acoustic scattering test evaluation target single-station electromagnetic scattering calculation method is as follows:
(1) the test signals acquired at each angle are processed using fourier transform methods,
S(m，f)＝FFT n (s r (m，t))；
(2) then, intercepting the amplitude value of the corresponding frequency to carry out amplitude normalization processing, and obtaining a single-station sound scattering value corresponding to an angle m & delta theta:
R(m·Δθ)＝normal(S(m，f 1 ))；
(3) the R (m · Δ θ) values at all angles are calculated in a cyclic manner, so as to obtain the target single-station electromagnetic scattering calculation result of the target acoustic scattering test, as shown in fig. 6.
Meanwhile, the calculation method for evaluating the electromagnetic scattering one-dimensional range profile of the target by the acoustic scattering of the target comprises the following steps:
and performing matched filtering processing on the acquired test signals, wherein y (t) IFFT (S (f) H (f) wins), namely the calculation result of the target acoustic scattering evaluation target electromagnetic scattering one-dimensional range profile.
Wherein S (f) is a received signal s r (t) Fourier transform S (f) FFT(s) r (t))， H(f)＝conj(FFT(s t (t))) is the system-dependent function s of the transmitted signal t (t) corresponding functions of FFT (-), IFFT (-), and conj (-), respectively, FFT (-), inverse Fourier transform, and complex conjugateAnd calculating wins as a Hamming window function.
And, the calculation method of the target acoustic scattering evaluation target electromagnetic scattering two-dimensional imaging comprises the following steps:
respectively carrying out two-dimensional Fourier transform on the distance and the direction by using an R-D algorithm as the electromagnetic scattering two-dimensional imaging calculation of the target, and assuming that originally received measurement data is s r (m, n), where m is azimuth sampling, n is range image sampling of time domain, IFFT processing is performed in range direction to obtain target range data IFFT in different azimuth n (s r (m, n)); then FFT processing is carried out in the azimuth direction, and the FFT of the two-dimensional imaging result of the target can be obtained m (IFFT n (sr (m, n))), namely, the target acoustic scattering evaluates the target electromagnetic scattering two-dimensional imaging result.
The invention has the beneficial effects that:
1. the method for evaluating the electromagnetic scattering characteristics through the three-dimensional target acoustic scattering comprises the steps of determining the electromagnetic scattering frequency of a three-dimensional target to be evaluated and the properties of a target medium, then determining the acoustic signal frequency, the pulse width, the sweep frequency width, the properties, the size and the volume of the target and the like required by a target acoustic scattering test according to a scaling relation, then installing the target required by the acoustic scattering test in an underwater acoustic compact field or a conventional water pool to perform the acoustic scattering test of the target at different angles, collecting and storing acoustic scattering echo signals at different angles, and finally processing the acoustic scattering echo signals by adopting amplitude calculation, pulse compression and an R-D two-dimensional imaging algorithm to obtain a target electromagnetic scattering characteristic result.
2. The method for evaluating the electromagnetic scattering characteristics through the three-dimensional target acoustic scattering evaluates the electromagnetic scattering characteristics of the target through simulation and test of the target acoustic scattering characteristics, and the target electromagnetic scattering characteristics comprise: the method is suitable for general underwater acoustic test and underwater acoustic compact field test, can correspond to general point-to-point microwave darkroom and microwave compact field test work in an electromagnetic environment, can effectively reduce the cost and technical difficulty of target electromagnetic scattering characteristic test and expand the technical method of target electromagnetic scattering characteristic evaluation, and inverts the electromagnetic scattering characteristic with higher frequency by using the acoustic scattering characteristic with lower frequency.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. A method for assessing electromagnetic scattering characteristics through acoustic scattering of a three-dimensional target, comprising the steps of:
1) determining the electromagnetic scattering frequency, the corresponding electromagnetic wave frequency, the pulse width, the sweep frequency bandwidth and the three-dimensional target property of the three-dimensional target to be evaluated, and taking the scaling coefficient r 1 ；
2) Determining a three-dimensional target which evaluates the acoustic wave frequency, the acoustic signal pulse width, the sweep frequency bandwidth and the corresponding acoustic properties of acoustic scattering test in electromagnetic scattering through the acoustic scattering of the three-dimensional target;
3) the three-dimensional target corresponding to the acoustic property is arranged in the silencing water pool for testing;
4) when a result of evaluating single-station electromagnetic scattering of a target through three-dimensional target acoustic scattering needs to be obtained, performing single-frequency point acoustic scattering test, and continuing to operate, and when a one-dimensional distance image of the target through three-dimensional target acoustic scattering evaluation and an ISAR result need to be obtained, performing linear frequency sweep acoustic scattering test with a certain bandwidth;
5) the three-dimensional target acoustic scattering single angle test process comprises the steps that a signal source generates a transmitting signal, the signal is transmitted after being amplified, an echo signal scattered by a target is received, and the echo signal is linearly amplified, filtered and stored;
6) according to the step 4, completing the acoustic scattering test of the three-dimensional target in different angle ranges with the required stepping angle;
7) if the single-frequency point acoustic scattering is adopted, a target acoustic scattering signal is intercepted from the acquired callback signal of each angle, FFT calculation is carried out, a single-station acoustic scattering test result of the three-dimensional target can be obtained, and the result is a result of evaluating single-station electromagnetic scattering of the target through the three-dimensional target acoustic scattering;
8) carrying out pulse compression processing on the acquired callback signals at a single angle to obtain a one-dimensional range profile result of the corresponding angle of the target to be detected, wherein the result is a result of evaluating the electromagnetic scattering one-dimensional range profile of the target through target acoustic scattering;
9) and (4) processing the multi-angle scattering echo signals collected in the step (6) by adopting an R-D algorithm to obtain an ISAR imaging result of the target, wherein the result is a result of evaluating electromagnetic scattering two-dimensional imaging of the target through acoustic scattering of the target.
2. The method for evaluating the electromagnetic scattering characteristics through the three-dimensional target acoustic scattering according to claim 1, wherein the method for determining the three-dimensional target for evaluating the acoustic scattering frequency, the acoustic signal pulse width, the sweep frequency bandwidth and the corresponding acoustic properties of the acoustic scattering test in the electromagnetic scattering through the three-dimensional target acoustic scattering in the step 2) is as follows:
a. when the target object is a conductor, the target object corresponding to the acoustic test is a rigid graph or an absolute elastomer, and the volume scale is reduced by r 1 Doubling;
b. when the target is a dielectric body, the reflection coefficient of the electromagnetic wave corresponding to the dielectric body is v 1 The material to be tested should be a common elastomer, and the acoustic reflection coefficient must be v 1 While simultaneously reducing the volume scale r 1 Doubling;
c. when the frequency of the electromagnetic wave to be evaluated is (f) e1 -f e2 ) (GHz) pulse time T e1 When the frequency of the corresponding sound wave is (f) s1 -f s2 ) (KHz) with a sonic pulse time of T s1 ＝2·10 5 ·T e1 /r 1 Wherein f is s1 ＝5·r 1 ·f e1 ，f s2 ＝5·r 1 ·f e2 When f is e1 ＝f e2 When f is present s1 ＝f s2 The test is a single frequency point test.
3. The method for evaluating the electromagnetic scattering characteristics of the three-dimensional target through acoustic scattering according to claim 1, wherein the step 7) uses a fourier transform method to process the test signals collected at each angle, and S (m, f) ═ FFT n (s r (m, t)), then intercepting the amplitude value corresponding to the frequency and carrying out amplitude normalization processing, so as to obtain the single-station sound scattering value R (m.delta theta) corresponding to the angle m.delta theta as normal (S (m, f) 1 ) And circularly calculating the R (m.delta theta) values of all angles to obtain the calculation result of the target single-station electromagnetic scattering of the target acoustic scattering test evaluation.
4. The method for evaluating the electromagnetic scattering characteristics through the acoustic scattering of the three-dimensional target according to claim 1, wherein the specific method for calculating the one-dimensional range profile of the target by using the pulse compression algorithm in the step 8) is as follows: performing matched filtering processing on the acquired test signal, wherein y (t) is IFFT (S (f '). H (f '). wins), namely the target acoustic scattering evaluation target electromagnetic scattering one-dimensional range profile calculation result, and S (f ') is a received signal S r (t) fourier transform S (f') -FFT (S) r (t))，H(f′)＝conj(FFT(s t (t))) is the system-dependent function s of the transmitted signal t And (t) respectively performing FFT (-), IFFT (-), and conj (-) on corresponding functions of the system, namely FFT (-), IFFT (-), and conj (-), and performing complex conjugate calculation, wherein wins is a Hamming window function.
5. The method for evaluating the electromagnetic scattering characteristics of the three-dimensional target through acoustic scattering according to claim 1, wherein in the step (nine), an R-D algorithm is used as a target electromagnetic scattering two-dimensional imaging calculation method, namely, two-dimensional Fourier transform is respectively carried out on the distance and the direction, and the originally received measurement data is assumed to be s r (m, n), where m is the number of azimuth sampling angles and n isIFFT processing is carried out on the distance image sampling number of the time domain in the distance direction, and target distance direction data IFFT in different directions can be obtained n (s r (m, n)); then FFT processing is carried out in the azimuth direction, and the FFT of the two-dimensional imaging result of the target can be obtained m (IFFT n (s r (m, n))), namely, the target acoustic scattering evaluates the target electromagnetic scattering two-dimensional imaging result.
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