CN-121978651-A - RCS near-far field transformation method and system based on synthetic aperture imaging

CN121978651ACN 121978651 ACN121978651 ACN 121978651ACN-121978651-A

Abstract

The invention provides a synthetic aperture imaging-based RCS near-far field conversion method and system, and belongs to the technical field of communication radars. By utilizing the progressive property of Hankel function cylindrical wave expansion under a cylindrical coordinate system and combining near-field scattering data, a strict RCS (radar scattering cross section) near-far field transformation algorithm is established, the problem of errors caused by wave front curvature in near-field measurement is solved, and the echo signal intensity of a target to be measured under far-field conditions can be accurately obtained. Based on the fusion of the multi-angle radar signals and the splicing of the near-far field transformation results, the high-resolution scattering characteristic image of the target to be detected can be synthesized. The method eliminates the distance coupling effect in near-field measurement while retaining the detail characteristics of the target, thereby more truly reflecting the electromagnetic scattering behavior of the target under far-field conditions.

Inventors

YANG MIN
SONG LIUWEI
SONG PENGZHAN
Geng Danfei

Assignees

西安讯昂信息技术有限公司

Dates

Publication Date: 20260505
Application Date: 20260303

Claims (10)

1. The RCS near-far field conversion method based on synthetic aperture imaging is characterized by comprising the following steps of: Acquiring position information of a turntable and a target to be detected, and arranging a plurality of radar antennas around the target to be detected to transmit radar signals; the method comprises the steps that a target to be detected receives radar emission signals, radar receiving signals are generated, two-dimensional imaging of the target to be detected and radar echo signals of the target to be detected are calculated based on the acquired position information of the target to be detected and the radar receiving signals, and an RCS near-far field transformation algorithm is determined based on the radar echo signals of the target to be detected; Under a cylindrical coordinate system, based on an RCS near-far field transformation algorithm, near-field scattering data of a target to be measured are obtained through cylindrical wave expansion of a Hankel function and progressive property measurement of the cylindrical wave expansion, echo signal intensities of the target to be measured on different observation angles of a far field region are calculated based on the near-field scattering data of the target to be measured, and the RCS near-far field transformation algorithm based on the Hankel method is determined through the near-field scattering data of the target to be measured and the echo signal intensities of the far field region; the RCS near-far field transformation algorithm based on the Hankel method is used for obtaining near-far field transformation results of all radar antennas of the target to be detected under different angles, and splicing the obtained near-far field transformation results to synthesize a high-resolution scattering characteristic image of the target to be detected.
2. The RCS near-far field conversion method based on synthetic aperture imaging according to claim 1, wherein the method for determining the RCS near-far field conversion algorithm based on the radar echo signal of the target to be detected is as follows: calculating a two-dimensional image of the target to be detected based on the acquired position information of the target to be detected and the radar receiving signal; Inverting a space reflectivity function of the target to be detected through two-dimensional Fourier transformation based on the two-dimensional imaging of the target to be detected; based on a space linear system theory, introducing a point source green function to describe the propagation characteristics of electromagnetic waves in space; According to the propagation characteristics of electromagnetic waves in space, calculating radar echo signals of the target to be detected under near field conditions and far field conditions by combining the space reflectivity function of the target to be detected; and determining an RCS near-far field transformation algorithm based on radar echo signals of the target to be detected under a near-field condition and a far-field condition.
3. The RCS near-far field transformation method based on synthetic aperture imaging according to claim 2, wherein the formula for calculating the two-dimensional imaging of the target to be detected based on the acquired position information of the target to be detected and the radar receiving signal is as follows: Wherein, the For two-dimensional imaging of an object to be measured, For the space area occupied by the object to be measured, As a function of the spatial reflectivity of the object to be measured, Any point of the target to be measured; For the time-domain signal transmitted by the radar, In order to achieve the light velocity, the light beam is, The time delay of the signal round trip between the target and the observation point is represented by R, which is the distance from the target point to the observation point.
4. The RCS near-far field conversion method based on synthetic aperture imaging according to claim 3, wherein in the step of calculating radar echo signals of the target to be measured under near-field conditions and far-field conditions according to propagation characteristics of electromagnetic waves in space and by combining a spatial reflectivity function of the target to be measured, a radar echo signal formula of the target to be measured under near-field conditions is as follows: The radar echo signal formula of the target to be detected under the far field condition is as follows: Wherein, the As the wave number of the signal, In units of imaginary numbers, Is the included angle between the rotary table and the coordinate axis, Is the source point location vector.
5. The RCS near-far field transformation method based on synthetic aperture imaging according to claim 4, wherein the method for determining the RCS near-far field transformation algorithm based on the Hankel method based on the near-field scattering data of the target under test and the echo signal intensity of the far field region at different observation angles of the target under test based on the near-field scattering data of the target under test and the echo signal intensity of the far field region by using the cylindrical wave expansion of the Hankel function and the progressive property measurement thereof under the cylindrical coordinate system is as follows: Establishing a near field scattering model under a cylindrical coordinate system, and calculating a near field scattering echo signal received by a target to be detected; Integrating the near field scattered echo signals through a two-dimensional free space Green function, and expanding the integrated near field scattered echo signals into superposition of cylindrical wave modes by utilizing a Hankel function addition theorem to obtain expansion of the near field scattered echo signals; under the condition that the measurement distance is far greater than the target size, performing far-field approximation on an amplitude term in the expansion of the near-field scattering echo signal to obtain a far-field scattering echo signal; And determining an RCS near-far field transformation algorithm based on a Hankel method based on the near-field scattered echo signal and the far-field scattered echo signal.
6. The RCS near-far field transformation method based on synthetic aperture imaging according to claim 5, wherein a near-field scattering model is built under a cylindrical coordinate system, and a formula for calculating a near-field scattering echo signal received by a target to be detected is as follows: Wherein, the Is a scattering density function of the object to be measured.
7. The RCS near-far field transformation method based on synthetic aperture imaging according to claim 6, wherein the formula for obtaining the far-field scattered echo signal is expressed as follows, under the condition that the measurement distance is far greater than the target size, by performing far-field approximation on the amplitude term in the expansion of the near-field scattered echo signal: Wherein, the Is a second type of hanker function; For the order of the number of steps, To at the same time Azimuth of the observation point.
8. The RCS near-far field transformation method based on synthetic aperture imaging according to claim 7, wherein the formula of the RCS near-far field transformation result of the Hankel method at the mth radar antenna is expressed as follows, wherein the RCS near-far field transformation result of each radar antenna of the target to be detected is obtained under different angles, the obtained near-far field transformation results are spliced, and the RCS near-far field transformation is performed based on the Hankel method in the step of synthesizing the high resolution scattering characteristic image of the target to be detected: Wherein, the Is azimuth angle Is used as a weight function of the (c), Is the pattern cut-off number.
9. An RCS near-far field conversion system based on synthetic aperture imaging, comprising: The data acquisition and radar emission module is used for acquiring the position information of the turntable and the target to be detected, and a plurality of radar antennas are arranged around the target to be detected to emit radar signals; The first algorithm determining module is used for receiving radar transmitting signals through the target to be detected, generating radar receiving signals, calculating two-dimensional imaging of the target to be detected and radar echo signals of the target to be detected based on the acquired position information of the target to be detected and the radar receiving signals, and determining an RCS near-far field transformation algorithm based on the radar echo signals of the target to be detected; The second algorithm determining module is used for obtaining near field scattering data of the target to be detected through cylindrical wave expansion and progressive property measurement of the cylindrical wave expansion of the Hankel function under a cylindrical coordinate system based on the RCS near-far field transformation algorithm, calculating echo signal intensities of the target to be detected on different observation angles of a far field region based on the near field scattering data of the target to be detected, and determining the RCS near-far field transformation algorithm based on the Hankel method through the near field scattering data of the target to be detected and the echo signal intensities of the far field region; the near-far field transformation module is used for acquiring near-far field transformation results of each radar antenna of the target to be detected under different angles based on an RCS near-far field transformation algorithm of the Hankel method, and splicing the acquired near-far field transformation results to synthesize a high-resolution scattering characteristic image of the target to be detected.
10. An electronic device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of the synthetic aperture imaging-based RCS near-far field transformation method of any one of claims 1 to 8.

Description

RCS near-far field transformation method and system based on synthetic aperture imaging Technical Field The invention belongs to the technical field of communication radars, and particularly relates to an RCS near-far field conversion method and system based on synthetic aperture imaging. Background Radar cross section (Radar Cross Section, RCS) testing is the core foundation in stealth technology and target electromagnetic property research. RCS testing technology plays a vital role in stealth design, performance evaluation and countermeasure research of targets such as aircrafts, ships, ground equipment and the like in the military and civil fields. The method is not only an important means for analyzing the electromagnetic scattering mechanism of the target, verifying a theoretical model and carrying out numerical simulation, but also a necessary technical support for developing a stealth weapon system with low observable characteristics and improving the outburst prevention and the viability of equipment. The stealth technology is essentially to effectively control the electromagnetic scattering characteristics of a target to realize low observability, and the main approaches include outline stealth design, namely guiding an incident electromagnetic wave to a non-threat direction through a specific geometric configuration, radar wave absorbing material technology, passive cancellation technology, active cancellation technology and active cancellation technology, wherein reflection energy is reduced by using the loss characteristics of the material to the electromagnetic wave, mutual cancellation of scattering fields is realized through ingenious design of a structure or the material, and active radiation signals are adopted to cancel scattering echoes of the target. In order to achieve accurate assessment of the stealth performance of a target, it is necessary to acquire its scattering data in a real or simulated electromagnetic environment through reliable and accurate RCS testing. Conventional RCS testing is typically performed in a test field (e.g., outdoor far field, compact field, etc.) that satisfies far field conditions, requiring the target to be under the irradiation of an incident plane wave to satisfy the measurement assumption of far field scattering. However, due to practical site size, testing environment, security requirements, and cost, it is difficult in many cases to establish a testing environment that meets stringent far field conditions, especially for large targets or high frequency testing scenarios. At this time, the RCS measurement performed is often obtained over a distance that does not satisfy far field conditions, which is a near field scatterometry. How to accurately acquire the far-field RCS of the target based on the near-field measurement data becomes a key problem in the test technology. By referring to the mature antenna near-field scanning and far-field pattern transformation theory in the antenna measurement field, near-field transformation research on radar target scattering characteristics is generated. The theory aims at establishing a mathematical relationship between the measured response of the target and the far-field scattering response thereof under the near-field irradiation and receiving conditions, so that the far-field RCS meeting the plane wave irradiation assumption is calculated through close-range scanning measurement. The method has important engineering application value in the aspects of realizing far-field equivalent test in a limited space, developing near-field detection characteristic research of the radar seeker, predicting response of the radar seeker in the near field based on the known far-field characteristic of the target and the like. Therefore, a near-far field RCS transformation algorithm and technology with high precision and high efficiency are developed, accurate reconstruction of the far-field RCS based on near-field scattering measurement is realized, and error sources in the transformation process are analyzed, evaluated and corrected, so that the method becomes an important research direction in the technical field of current RCS testing. In order to fundamentally solve the above problems, a novel near-far field conversion method and processing system which are compatible with high precision and high efficiency are needed. Disclosure of Invention The invention aims to overcome the defects and provide an RCS near-far field conversion method and system based on synthetic aperture imaging. In order to achieve the above purpose, the invention adopts the following technical scheme: In a first aspect, the invention provides an RCS near-far field conversion method based on synthetic aperture imaging, comprising the following steps: Acquiring position information of a turntable and a target to be detected, and arranging a plurality of radar antennas around the target to be detected to transmit radar signals; the method comprises the st