CN108388732A - Plunder extra large Target multipath scattering properties emulated computation method and system - Google Patents
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Abstract
The embodiment of the present invention proposes that one kind plunderring extra large Target multipath scattering properties emulated computation method and system, is related to radar target signature technical field, this method includes：Face element processing is carried out to sea sample；The local sea bin scattering rate of face elementization treated sea sample is calculated by double two time scales approach；Radar electromagnetic wave induced electricity magnetic current caused by the surface of objective body and seamed edge structure is calculated separately by physical optical method and Equivalent currents method；By itself scattering properties of mirror method combining target and sea, the multipath coupling scattering on target sea is calculated.It is provided in an embodiment of the present invention to plunder extra large Target multipath scattering properties emulated computation method and system, it can reflect the locally coupled scattering properties on sea and target in true radar what comes into a driver's, to which accurate simulation plunders the multiple scattering characteristic of extra large target, it can be used for plunderring the remote sensing of extra large target.
Description
Technical Field
The invention relates to the technical field of radar target characteristics, in particular to a sea-sweeping target multipath scattering characteristic simulation calculation method and system.
Background
China has a long coastline, and the goal of low-altitude penetration prevention by sea skimming is one of the main threats faced by the air defense system of China. At present, the advanced cruise missile and anti-ship missile at foreign countries can rush to the sea at a height of as low as 5m, can accurately strike core military targets such as large-scale surface vessels, shore protection facilities, nuclear bases, war factories, command centers and the like, and form great threat to soil defense. When the radar system is used for detecting and tracking the sea-sweeping target, the radar echo is easily interfered by multipath scattering. Referring to fig. 1, fig. 1 shows a schematic diagram of multipath scattering of an ultra-low altitude target of a radar seeker, and the multipath scattering can enter a radar along with a target echo to form severe interference on a radar system, so that abnormal phenomena such as fluctuation of the radar echo, out-of-tracking, false alarm and the like are caused. The multipath interference has strong target-like characteristics, and compared with other radar interference, the multipath interference is difficult to separate and inhibit in the space, time and frequency domains of radar echoes. The method has the advantages that the multi-path scattering characteristics of the sea-sweeping low-flying target and the influence of the multi-path scattering characteristics on a radar and a guidance system are researched, and the method has important significance in evaluating, improving and promoting the ultra-low altitude performance of weapon equipment of an air defense system. However, due to the complexity of the marine environment, the cost for researching the multipath scattering characteristic by adopting an experimental means is high, and the actually measured data is not easy to obtain under a plurality of real and complex conditions, so that the method has certain limitations. In comparison, the digital simulation is carried out by adopting a theoretical model, and the method has the remarkable advantages of low cost, high flexibility, wide application range and the like.
Disclosure of Invention
The invention aims to provide a sea-sweeping target multipath scattering characteristic simulation calculation method and a sea-sweeping target multipath scattering characteristic simulation calculation system, which can reflect local coupling scattering characteristics of a sea surface and a target.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
the embodiment of the invention provides a sea-swept target multipath scattering characteristic simulation calculation method, which comprises the following steps:
performing binning treatment on the sea surface samples;
calculating the local sea surface element scattering rate of the sea surface sample subjected to binning processing by adopting a bin double-scale algorithm;
obtaining induced electromagnetic current generated by radar electromagnetic waves on the surface and edge structures of a target body according to a physical optical algorithm and an equivalent electromagnetic current algorithm;
correcting mirror image radar electromagnetic waves generated by the radar electromagnetic waves on the local sea surface element and mirror image induced electromagnetic currents generated by the mirror image radar electromagnetic waves on the surface and edge structure of the target body according to the scattering rate of the local sea surface element;
and determining the scattered field of the radar electromagnetic wave on the surface and the edge structure of the target body according to the induced electromagnetic flow generated by the radar electromagnetic wave and the corrected image induced electromagnetic flow generated by the image radar electromagnetic wave.
Further, the step of binning the sea surface samples includes:
processing the Efouhaily sea spectrum model by adopting a Monte Carlo method according to a random rough surface theory to obtain a sea surface sample;
and performing surface binning treatment on the large-scale contour surface of the sea surface sample.
Further, according to the dual-scale theory, the scattered field of the local sea surface element of the sea surface sample includes a coherent component and an incoherent component, and the scattering rate of the local sea surface element is represented as:
wherein,the scattering coefficient of the coherent component of the scattering field of the local sea surface element is represented and obtained by adopting a Kirhoff approximate algorithm,and (3) representing the scattering coefficient of the incoherent component of the scattering field of the local sea surface element, and obtaining the scattering coefficient by adopting a perturbation method.
Further, after the coherent component is processed by using a Kirhoff approximation algorithm, the scattering rate of the local sea surface element is represented as:
wherein q represents the scattering vector, ΓpqAnd (3) characterizing a coherent polarization scattering coefficient, and prob (-) characterizes a probability density function of sea surface large-scale surface element distribution.
Further, after the incoherent component is processed by using a perturbation method, the scattering rate of the local sea surface element is represented as:
wherein, FpqCharacterisation of incoherent polarised scattering coefficient, Wζ(ql) And characterizing the spectral distribution of the microstructure on the local sea surface element.
Further, the induced electromagnetic current generated by the radar electromagnetic wave on the surface and edge structure of the target body is expressed as:
after the surface of the target body is subdivided by adopting a planar triangular surface element, a scattering field generated by the local sea surface element in a remote area is expressed as follows:
wherein Δ S represents the area of the planar triangular corner element, I represents the phase portion, and
further, the equivalent current J generated by the radar electromagnetic wave on the edge structure of the target bodyeAnd an equivalent magnetic current JmAre respectively:
the expression of the diffraction field generated by the edge structure of the target body in the far zone is as follows:
wherein,tangent vector characterizing the edge structure of the target body, EiAnd HiRespectively representing the incident electric field and the incident magnetic field generated by the radar electromagnetic wave on the edge structure of the target body, βiAnd βsRespectively representing an included angle generated by the incident direction of the radar electromagnetic wave and the edge structure of the target body and an included angle generated by the scattering direction of the radar electromagnetic wave and the edge structure of the target body, DeAnd DmAre diffraction coefficients.
Further, the step of determining a fringe field of the radar electromagnetic wave generated on the surface and edge structure of the target body according to the induced electromagnetic current generated by the radar electromagnetic wave and the mirror image induced electromagnetic current generated by the mirror image radar electromagnetic wave includes:
and taking the result of vector summation of the induced electromagnetic flow generated by the radar electromagnetic wave and the mirror image induced electromagnetic flow generated by the mirror image radar electromagnetic wave as a scattered field generated by the radar electromagnetic wave on the surface and edge structure of the target body.
The embodiment of the invention also provides a sea-swept target multipath scattering characteristic simulation calculation system, which comprises:
the sea surface sample processing module is used for performing binning processing on the sea surface samples;
the scattering rate calculation module is used for calculating the local sea surface element scattering rate of the binned sea surface sample by adopting a binned dual-scale algorithm;
the induced electromagnetic current calculation module is used for obtaining the induced electromagnetic current generated by the radar electromagnetic wave on the surface and the edge structure of the target body according to a physical optical algorithm and an equivalent electromagnetic current algorithm;
the correction module is used for correcting mirror image radar electromagnetic waves generated by the radar electromagnetic waves on the local sea surface element and mirror image induced electromagnetic currents generated by the mirror image radar electromagnetic waves on the surface and edge structure of the target body according to the scattering rate of the local sea surface element;
and the scattered field simulation module is used for determining the scattered field of the radar electromagnetic wave generated on the surface and the edge structure of the target body according to the induced electromagnetic flow generated by the radar electromagnetic wave and the corrected image induced electromagnetic flow generated by the image radar electromagnetic wave.
Further, the surface sample processing module comprises:
the sea surface sample processing unit is used for processing the Efouhailaly sea spectrum model by adopting a Monte Carlo method according to a random rough surface theory so as to obtain a sea surface sample;
and the binning unit is used for binning the large-scale profile surface of the sea surface sample.
Compared with the prior art, the sea grazing target multipath scattering characteristic simulation calculation method and system provided by the embodiment of the invention simulate a real sea profile sample at each quasi-static time by adopting a random rough surface theory and combining a sea spectrum function and a Monte Carlo method, simultaneously perform binning processing on a large-scale sea surface profile, calculate scattering of the sea surface bin through a corrected bin double-scale model, count coupling scattering of a local bin and a target by combining a mirror image method, and perform coherent superposition SAR images, etc.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 shows a radar seeker ultra-low altitude target multipath scattering diagram;
FIG. 2 is a schematic diagram showing the mirror image of an ultra-low-altitude target under radar illumination;
FIG. 3 is a schematic flow chart of a sea-swept target multipath scattering characteristic simulation calculation method according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a sea surface two-scale model and a sea-sweeping target mirror image provided by an embodiment of the invention;
FIG. 5 is a schematic diagram of a sea surface bin model at a wind speed of 3m/s at a height of 10m above sea surface;
FIG. 6 is a diagram showing the mirror scattering coefficients of a sea surface bin VV under polarization;
FIG. 7 illustrates a bin mirroring process diagram;
FIG. 8 is a schematic flow chart of the substeps of step S100 in FIG. 3;
FIG. 9 shows the calculation result of HH polarization in multipath scattering calculation;
fig. 10 shows the calculation result of VV polarization in the multipath scattering calculation;
FIG. 11 shows a high resolution range image of a target volume;
FIG. 12 shows a high-resolution range image of a target above the sea surface at low sea conditions;
FIG. 13 shows a high-resolution range image of a target above a sea surface at high sea conditions;
FIG. 14 SAR imaging of a target volume;
FIG. 15 shows SAR imaging of a target volume above the sea surface at low sea conditions;
FIG. 16 shows SAR imaging of a target volume above the sea surface at high sea conditions;
FIG. 17 is a schematic block diagram of a sea-swept target multipath scattering characteristics simulation calculation system according to an embodiment of the present invention;
fig. 18 is a schematic structural diagram of a sea surface sample processing module of a sea-swerving target multipath scattering characteristic simulation calculation system according to an embodiment of the present invention.
In the figure: 10-sea-swept target multipath scattering characteristic simulation calculation system; 100-sea surface sample processing module; 110-sea surface sample processing unit; 120-binning units; 200-a scattering power calculation module; 300-an induced electromagnetic current calculation module; 400-a correction module; 500-scattered field simulation module.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. 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.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
Some embodiments of the invention are described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
The traditional accurate electromagnetic field full wave numerical simulation method is a scheme for solving the multipath scattering simulation problem. The scheme can obtain a relatively accurate calculation result when calculating the pure target electromagnetic scattering, but is limited by the calculation electrical scale and the calculation complexity when calculating the real sea environment and the target multipath scattering. Analytical methods are another solution, for example, currently most used is the Joel t.johnson at state university in ohio, usa, which proposes a "four-path" model that considers that the multipath scattering of a target on the sea surface can be calculated by superposition of four paths of scattered echoes, including the target, the direct echo of the sea surface, and the coupled scattered echoes that pass through the two paths of the target-surface-radar, surface-target-radar, where the scattering of the sea surface is given by empirical scattering coefficients. The model has simple mechanism and high simulation efficiency, and can roughly calculate the multipath scattering of the sea-sweeping target. However, the model still has limitations in complex sea situations, because the sea surface reflection mechanism is mainly diffuse scattering, and therefore sea surface local scattering and local coupling scattering need to be considered. In complex sea situations, the multipath scattering characteristics are very complex, and have a relationship with the local scattering characteristics of the target and the sea surface, and if the sea surface is regarded as a special 'mirror', each local sea surface generates a mirror image of the target. Referring to fig. 2, fig. 2 is a schematic diagram illustrating a mirror image of an ultra-low-altitude target under radar illumination, the target generates a corresponding independent mirror image for each local bin, and the distribution of the mirror images is related to a large-scale profile rough profile.
Based on the above principle, the inventor proposes a sea-swept target multipath scattering characteristic simulation calculation method in actual work as follows: according to the random rough surface theory, a sea spectrum function is combined with a Monte Carlo method to simulate a real sea profile sample at each quasi-static time, the large-scale sea surface profile is subjected to binning processing, scattering of the sea surface bin is calculated through a corrected bin double-scale model, coupling scattering of each local bin and a target is counted through a mirror image method, and then coherent superposition is carried out, so that the sea grazing target multipath scattering characteristics under various sea conditions can be accurately and efficiently simulated. Referring to fig. 3, fig. 3 is a schematic flow chart of a method for calculating a multipath scattering characteristic simulation of a sea-swept target according to an embodiment of the present invention, where the method includes the following steps:
and S100, performing binning processing on the sea surface samples.
Referring to fig. 4, fig. 4 shows a sea surface dual-scale model diagram provided by the embodiment of the invention, a sea surface capillary wave structure attached to a large surface element can be decomposed into a series of superposition of spatial sine waves, according to the Bragg scattering theory, only along the radar sight direction, and a wave component with a Bragg resonance frequency mainly contributes to sea surface scattering, and the capillary wave component can be simplified into a monochromatic sine wave with a Bragg resonance wavelength, wherein the expression is ξ (r) ═ B (k κ)c)cos(κc·r-ωct)。
Wherein, κcCharacterizing the Bragg harmonic wave number vector, ωcCharacterizing resonant wave angular frequency, r ═ xc,yc) The position coordinates on the characterizing bin,the capillary amplitude characterizing the Bragg scattering caused by this bin, Δ S characterizing the area of the small bin, S (κ)c) The high frequency part of the elfouhailary sea spectrum is characterized.
S200, calculating the local sea surface element scattering rate of the sea surface sample subjected to binning processing by adopting a surface element double-scale algorithm.
Referring again to fig. 4, after the global coordinate system is established on the sea surface, according to the dual-scale theory, the scattering field of the local sea surface element of the sea surface sample includes a coherent component and an incoherent component, and the scattering rate of the local sea surface element can be expressed as
Wherein,the scattering coefficient of the coherent component of the local sea surface element is represented and obtained by using a Kirhoff Approximation algorithm (KA),and (3) representing the scattering coefficient of the incoherent component of the local sea surface element, and calculating by adopting a Perturbation Method (SPM).
Further, after the coherent component is processed by using the Kirhoff approximation algorithm, the scattering rate of the local sea surface element can be further expressed as
Wherein q represents the scattering vector, ΓpqAnd (3) characterizing a coherent polarization scattering coefficient, and prob (-) characterizes a probability density function of sea surface large-scale surface element distribution.
Further, after the incoherent component is processed by the perturbation method, the scattering rate of the local sea surface element is represented as:
wherein, FpqCharacterisation of incoherent polarised scattering coefficient, Wζ(ql) The spectral distribution of the microstructure over the local sea surface element is characterized.
Referring to fig. 5, fig. 5 shows a schematic diagram of a sea surface bin model at a height of 10m above sea surface and a wind speed of 3m/s, wherein the bin size is 1m × 1m in a large-scale sea surface model generated by the monte carlo method according to the Elfouhaily sea spectrum. Referring to fig. 6, fig. 6 shows a schematic diagram of the mirror scattering coefficient of a surface element under the VV polarization condition of a sea surface element, when radar electromagnetic waves are incident at 45 ° along the X-axis direction, and the frequency is 10 GHz.
S300, obtaining induced electromagnetic current generated by radar electromagnetic waves on the surface and edge structures of the target body according to a physical optical algorithm and an equivalent electromagnetic current algorithm.
The surface of the target body is considered as an ideal conductor structure, the radar electromagnetic wave irradiates the surface of the target body to excite induced current on the surface of the target body, diffraction current can be excited on the edge structure, and the induced electromagnetic current generated by the radar electromagnetic wave on the surface of the target body and the edge structure is expressed as:
after the surface of the target body is subdivided by adopting the planar triangular surface element, a scattering field generated by the local sea surface element in a far zone is expressed as follows:
wherein Δ S represents the area of the planar triangular corner element, I represents the phase portion, and
further, assume JeAnd JmRespectively representing the equivalent current and the equivalent magnetic current generated by radar electromagnetic waves at the edge structure of the target body, namely the equivalent current JeAnd an equivalent magnetic current JmAre respectively:
the expression of the diffraction field generated by the edge structure of the target body in the far zone is as follows:
wherein,tangent vector characterizing the edge structure of the target body, EiAnd HiRespectively representing the incident electric field and the incident magnetic field generated by the radar electromagnetic wave on the edge structure of the target body, βiAnd βsCharacterised by the direction of incidence of the radar waves and the target body, respectivelyThe angle between the edge structure and the angle between the scattering direction of the radar waves and the edge structure of the target, DeAnd DmAre diffraction coefficients.
S400, correcting mirror image radar electromagnetic waves generated by the radar electromagnetic waves on the local sea surface element and mirror image induced electromagnetic currents generated by the mirror image radar electromagnetic waves on the surface and edge structure of the target body according to the scattering rate of the local sea surface element.
Referring again to fig. 2, fig. 2 shows the process of mirroring a point target to the sea, and for an actual extended target, each part of the target generates a corresponding mirror image target for a mirror image surface element when the mirror image condition is satisfied, and at the same time, a transmitting source of the radar as a radar electromagnetic valve is also mirrored by the mirror image surface element to generate a corresponding mirror image source, referring again to fig. 4, at this time, the multipath coupling scattering of the target and the sea environment is equal to the superposition of the actual target and the mirror image target.
Referring to fig. 7, fig. 7 is a schematic diagram illustrating a bin mirroring process, where an induced current generated on a surface of a target body by irradiation of radar electromagnetic waves on the target body is J1The incident wave vector generates a mirror image vector for the illuminated sea surface element, and irradiates the original target body to generate induced current distribution J2If a certain point can perform mirror reflection on a sea surface element, a mirror image source J is generated at the mirror image position1image(ri′mage)，J2image(ri′mage) The total scattered field is the superposition of the scattering contributions of the four parts of the current distribution. Thus:
J1image(jximage,jyimage,jzimage)＝ρJ1(jximage,jyimage,jzimage)，
wherein ρ represents a mirror correction factor, and the expression is:
it is worth to be noted that, as can be seen from the expression of the mirror image correction factor, the mirror image correction factor includes the scattering characteristics of the surface element, which is mainly described by a double-scale method of half-definite surface element, and the mirror image scattering contribution is calculated by the mirror image reflection distance; the modulation of the capillary waves, micro-roughness structures, determines the details of the ground and sea surface, and the contribution of diffuse reflection can be calculated by Bragg resonance (Bragg resonance) theory.
S500, determining a scattered field of the radar electromagnetic wave generated on the surface and the edge structure of the target body according to the induced electromagnetic flow generated by the radar electromagnetic wave and the corrected mirror image induced electromagnetic flow generated by the mirror image radar electromagnetic wave.
In this embodiment, the result of vector summation of the induced electromagnetic current generated by the radar electromagnetic wave and the mirror image induced electromagnetic current generated by the mirror image radar electromagnetic wave is used as the fringe field generated by the radar electromagnetic wave on the surface and edge structure of the target body.
Referring to fig. 8, fig. 8 is a schematic flowchart of the sub-steps of step S100 in fig. 3, in the present embodiment, step S100 includes the following sub-steps:
and S110, processing the Efouhailaly sea spectrum model by adopting a Monte Carlo method according to a random rough surface theory to obtain a sea surface sample.
In this embodiment, for the Efouhaily sea spectrum model, a monte carlo method is adopted to perform preprocessing according to a random rough surface theory, so as to obtain a sea surface sample.
And S120, performing surface binning treatment on the large-scale contour surface of the sea surface sample.
In this embodiment, after the sea surface samples are obtained in step S110, the large-scale contours in the obtained sea surface samples are subjected to binning processing, so as to simulate the spatial distribution of the sea surface relief contours.
In a specific embodiment, assuming that the frequency of the radar electromagnetic wave is 10GHz, the target body is a 'battle axe type' cruise missile, and the incident angle of the radar electromagnetic wave on the target body is 45 degrees. Referring to fig. 9, fig. 9 shows the calculation result of HH polarization in the multipath scattering calculation, and referring to fig. 10, fig. 10 shows the calculation result of VV polarization in the multipath scattering calculation. It can be seen that when the target body flies at a low speed, the multipath effect has obvious enhancement effect on the backscattering of the radar; moreover, when the height of the target body is lower, the enhancement effect is more obvious; also, the enhancement of HH polarization is stronger than VV polarization.
To further see the effect of multipath scattering on the scattering properties of the target radar, we continued to simulate the high-resolution range profile of the radar using this method, see fig. 11, 12 and 13, where fig. 11 shows the high-resolution range profile of the target volume, fig. 12 shows the high-resolution range profile of the target volume above the sea surface at low sea conditions, and fig. 13 shows the high-resolution range profile of the target volume above the sea surface at high sea conditions. At this time, a frequency stepping signal form is adopted, the radar bandwidth is 350MHz, the frequency stepping interval is 3.5MHz, and the radar polarization is HH polarization, so that it can be seen that the multipath effect also has a great influence on the range profile of the radar when the target body flies at a low speed. In the distance image of a pure target body, three main strong scattering points with different strengths on the head, the wing and the tail of the cruise missile can be clearly distinguished. In the sea surface under the low sea condition, the wind speed 10m above the sea surface in the sea spectrum function is selected to be 5m/s, and it can be seen that the strength of the multipath interference is higher, most scattering points of a target body can be submerged, and the detection and identification of the target are difficult. In the sea surface under high sea condition, the wind speed is 10m/s, the multipath scattering intensity becomes small, the energy is relatively dispersed, and more scattering points of the original target body can be identified.
To further observe the multipath scattering characteristics, please refer to fig. 14, 15 and 16, fig. 14 is a SAR image of a target body, fig. 15 shows the SAR image of the target body above the sea surface under low sea conditions, fig. 16 shows the SAR image of the target body above the sea surface under high sea conditions, and the SAR adopts an airborne front-side simulation model.
Based on the design, the sea surface object multipath scattering characteristic simulation calculation method provided by the embodiment of the invention simulates a real sea profile sample under each quasi-static time by adopting a random rough surface theory and combining a sea spectrum function and a Monte Carlo method, simultaneously carries out binning processing on a large-scale sea surface profile, the scattering of the sea surface element is calculated by a corrected element double-scale model, and calculates the coupling scattering of a local element and an object by combining a mirror image method and then carries out coherent superposition, so that the sea surface object multipath scattering characteristic above the large-scale sea surface under complex sea condition electricity can be accurately and efficiently simulated SAR images, etc.
Referring to fig. 17, fig. 17 shows a schematic structural diagram of a sea-swerving target multipath scattering characteristic simulation calculation system 10 according to an embodiment of the present invention, in this embodiment, the sea-swerving target multipath scattering characteristic simulation calculation system 10 includes a sea surface sample processing module 100, a scattering rate calculation module 200, an induced electromagnetic current calculation module 300, a correction module 400, and a scattered field simulation module 500. Wherein,
the sea surface sample processing module 100 is used for performing binning processing on the sea surface samples.
The scattering rate calculation module 200 is configured to calculate a local sea surface bin scattering rate of the binned sea surface sample by using a bin dual-scale algorithm.
The induced electromagnetic current calculating module 300 is configured to obtain an induced electromagnetic current generated by the radar electromagnetic wave on the surface and edge structure of the target according to a physical optical algorithm and an equivalent electromagnetic current algorithm.
The correction module 400 is configured to correct, according to the scattering rate of the local sea surface element, a mirror image radar electromagnetic wave generated by the radar electromagnetic wave on the local sea surface element and a mirror image induced electromagnetic current generated by the mirror image radar electromagnetic wave on the surface and edge structure of the target body.
The fringe field simulation module 500 is configured to determine a fringe field generated by the radar electromagnetic wave on the surface and edge structure of the target according to the induced electromagnetic flow generated by the radar electromagnetic wave and the corrected image induced electromagnetic flow generated by the image radar electromagnetic wave.
Referring to fig. 18, fig. 18 shows a schematic structural diagram of a sea surface sample processing module 100 of a sea-swept object multipath scattering characteristic simulation calculation system 10 according to an embodiment of the present invention, in this embodiment, the sea surface sample processing module 100 includes a sea surface sample processing unit 110 and a surface element unit 120. Wherein,
the sea surface sample processing unit 110 is configured to process the Efouhaily sea spectrum model by using a monte carlo method according to a random rough surface theory, so as to obtain a sea surface sample.
The binning unit 120 is configured to bin the large-scale contour surface of the sea surface sample.
In summary, according to the sea-grazing target multipath scattering characteristic simulation calculation method and system provided by the embodiments of the present invention, the random rough surface theory and the sea spectrum function are combined with the monte carlo method to simulate the real sea profile sample at each quasi-static time, the large-scale sea surface profile is subjected to binning processing, the scattering of the sea surface bin is calculated by the modified bin dual-scale model, the coupling scattering of the local bin and the target is calculated by combining the mirror image method and then is subjected to coherent superposition, the multi-path scattering characteristic of the target above the sea surface with the large scale of the complicated sea condition can be accurately and efficiently simulated, compared with the conventional calculation model and method, the local coupling scattering characteristic of the sea surface and the target can be reflected, so that the multi-path scattering of the sea-grazing target can be more accurately and efficiently calculated, and the method and the system can be more easily applied to observe the multi-path scattering of the sea surface target one-, SAR images, etc.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Claims (10)
1. A sea-swept target multipath scattering characteristic simulation calculation method is characterized by comprising the following steps:
performing binning treatment on the sea surface samples;
calculating the local sea surface element scattering rate of the sea surface sample subjected to binning processing by adopting a bin double-scale algorithm;
obtaining induced electromagnetic current generated by radar electromagnetic waves on the surface and edge structures of a target body according to a physical optical algorithm and an equivalent electromagnetic current algorithm;
correcting mirror image radar electromagnetic waves generated by the radar electromagnetic waves on the local sea surface element and mirror image induced electromagnetic currents generated by the mirror image radar electromagnetic waves on the surface and edge structure of the target body according to the scattering rate of the local sea surface element;
and determining the scattered field of the radar electromagnetic wave on the surface and the edge structure of the target body according to the induced electromagnetic flow generated by the radar electromagnetic wave and the corrected image induced electromagnetic flow generated by the image radar electromagnetic wave.
2. The method of claim 1, wherein the step of binning the sea surface samples comprises:
processing the Efouhaily sea spectrum model by adopting a Monte Carlo method according to a random rough surface theory to obtain a sea surface sample;
and performing surface binning treatment on the large-scale contour surface of the sea surface sample.
3. The method of claim 1, wherein the scattered field of the local sea surface bin of the sea surface sample comprises a coherent component and a non-coherent component according to a two-scale theory, and wherein the scattering ratio of the local sea surface bin is represented as:
wherein,the scattering coefficient of the coherent component of the local sea surface element is represented and obtained by adopting a Kirhoff approximate algorithm,and characterizing the scattering coefficient of the incoherent component of the local sea surface element, and obtaining the scattering coefficient by adopting a perturbation method.
4. The method of claim 3, wherein after processing the coherent component using a Kirhoff approximation algorithm, the scattering ratio of the local sea surface bins is expressed as:
wherein q represents the scattering vector, ΓpqAnd (3) characterizing a coherent polarization scattering coefficient, and prob (-) characterizes a probability density function of sea surface large-scale surface element distribution.
5. The method of claim 4, wherein after the perturbation method is used to process the incoherent component, the scattering power of the local sea surface bin is expressed as:
wherein, FpqCharacterisation of incoherent polarised scattering coefficient, Wζ(ql) And characterizing the spectral distribution of the microstructure on the local sea surface element.
6. The method of claim 1, wherein the induced electromagnetic current generated by the radar waves on the surface and edge structure of the target is expressed as:
after the surface of the target body is subdivided by adopting a planar triangular surface element, a scattering field generated by the local sea surface element in a remote area is expressed as follows:
wherein Δ S represents the area of the planar triangular corner element, I represents the phase portion, and
7. the method of claim 6, wherein the radar waves generate an equivalent current J at the edge structure of the targeteAnd an equivalent magnetic current JmAre respectively:
the expression of the diffraction field generated by the edge structure of the target body in the far zone is as follows:
wherein,tangent vector characterizing the edge structure of the target body, EiAnd HiRespectively representing the incident electric field and the incident magnetic field generated by the radar electromagnetic wave on the edge structure of the target body, βiAnd βsRespectively representing an included angle generated by the incident direction of the radar electromagnetic wave and the edge structure of the target body and an included angle generated by the scattering direction of the radar electromagnetic wave and the edge structure of the target body, DeAnd DmAre diffraction coefficients.
8. The method of claim 1, wherein the step of determining the fringe field generated by the radar wave on the surface and edge structure of the target based on the induced electromagnetic current generated by the radar wave and the mirror induced electromagnetic current generated by the mirror radar wave comprises:
and taking the result of vector summation of the induced electromagnetic flow generated by the radar electromagnetic wave and the mirror image induced electromagnetic flow generated by the mirror image radar electromagnetic wave as a scattered field generated by the radar electromagnetic wave on the surface and edge structure of the target body.
9. A sea-swept target multipath scattering characteristics simulation calculation system, the system comprising:
the sea surface sample processing module is used for performing binning processing on the sea surface samples;
the scattering rate calculation module is used for calculating the local sea surface element scattering rate of the binned sea surface sample by adopting a binned dual-scale algorithm;
the induced electromagnetic current calculation module is used for obtaining the induced electromagnetic current generated by the radar electromagnetic wave on the surface and the edge structure of the target body according to a physical optical algorithm and an equivalent electromagnetic current algorithm;
the correction module is used for correcting mirror image radar electromagnetic waves generated by the radar electromagnetic waves on the local sea surface element and mirror image induced electromagnetic currents generated by the mirror image radar electromagnetic waves on the surface and edge structure of the target body according to the scattering rate of the local sea surface element;
and the scattered field simulation module is used for determining the scattered field of the radar electromagnetic wave generated on the surface and the edge structure of the target body according to the induced electromagnetic flow generated by the radar electromagnetic wave and the corrected image induced electromagnetic flow generated by the image radar electromagnetic wave.
10. The system of claim 9, wherein said surface sample processing module comprises:
the sea surface sample processing unit is used for processing the Efouhailaly sea spectrum model by adopting a Monte Carlo method according to a random rough surface theory so as to obtain a sea surface sample;
and the binning unit is used for binning the large-scale profile surface of the sea surface sample.
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