A radar simulation method and device based on dynamic polarization loss calculation

Abstract

The present application discloses a radar simulation method and device based on dynamic polarization loss calculation. The method calculates the first electric field vector of the electromagnetic wave emitted by the opponent's antenna, which is described in the antenna coordinate system of the opponent's antenna and only considers the polarization characteristics of the opponent's antenna. Calculate the second electric field vector of the electromagnetic wave emitted by our antenna, which is described in the antenna coordinate system of our antenna and only considers the polarization characteristics of our antenna. The first electric field vector is converted to the North Celestial East coordinate system to obtain the third electric field vector. The second electric field vector is converted to the North Celestial East coordinate system to obtain the fourth electric field vector. The dot product calculation is performed on the third electric field vector and the fourth electric field vector to obtain the fifth electric field vector; the dynamic polarization loss is also obtained. The present application fully considers the actual environment in which our antenna and the opponent's antenna may be in motion, calculates a more accurate dynamic polarization loss, and can improve the accuracy of radar simulation.

Description

Technical Field

[0001] The present application relates to a radar simulation technology, and in particular to a radar digital simulation method based on polarization loss calculation. Background Art

[0002] In modern radar systems, polarization is a key parameter that has a significant impact on the detection capability of targets. Polarization describes the vibration mode of electromagnetic waves. The direction of the vibration of the electric field (electromagnetic wave) is the polarization direction of the electromagnetic wave. According to the motion trajectory of the end of the electric field vector, polarization can be divided into three categories: linear polarization, circular polarization, and elliptical polarization. Linear polarization is further divided into horizontal polarization and vertical polarization (the two are orthogonal). Circular polarization is divided into left-hand circular polarization and right-hand circular polarization (the two are orthogonal).

[0003] Assuming that the propagation direction of the electromagnetic wave is z, the transverse electric field E perpendicular to the z direction can be decomposed into the electric field component E in the x direction. x and the electric field component E in the y direction y , the x-direction, y-direction and z-direction form a three-dimensional rectangular coordinate system, that is . , Where E1 and E2 are the amplitudes of the linear polarization waves in the x and y directions respectively; ω represents the angular frequency of the electromagnetic wave, which describes the oscillation frequency of the electromagnetic wave; t represents time; β represents the propagation constant, which defines the phase change of the electromagnetic wave in the propagation direction (here in the z direction); z represents the position coordinate in the propagation direction of the electromagnetic wave; δ represents E y Lag behind E x phase.

[0004] When E y and E x When the phase difference is 0 degree or 180 degrees, E x and E y The phase of the synthetic electric field E is constant, the amplitude changes with time, and the vector end trajectory of the synthetic electric field E is a straight line, so it is called linear polarization.

[0005] When E y and E x When the amplitudes of the two are equal and the phase difference is 90 degrees or -90 degrees, E x and E y The amplitude of the synthetic electric field E is constant, the phase changes with time, and the vector end trajectory of the synthetic electric field E is circular, so it is called circular polarization. y Phase advance E x It is right-hand circular polarization, and vice versa it is left-hand circular polarization.

[0006] When E yand E x When the above two conditions are not met, it is elliptical polarization. Linear polarization and circular polarization can be considered as special cases of elliptical polarization, so elliptical polarization can be used to cover all polarization modes.

[0007] The main polarization refers to the polarization of the radio wave radiated in the direction of the antenna's maximum radiation, which is defined as the trajectory of the movement of the electric field vector endpoint in the direction of the antenna's maximum radiation. Due to the physical structure of the antenna itself and other reasons, the electric field vector of the far field radiated by the antenna not only moves in the required direction, but also has a component in its orthogonal direction. This is the cross-polarization of the antenna.

[0008] The electric field vector in the main polarization direction (assuming it is the x direction) is The mathematical representation of is as follows: .in, represents the amplitude in the main polarization direction; ω represents the angular frequency of the electromagnetic wave; t represents time; Indicates the initial phase angle of the main polarization direction; The unit vector representing the direction of the principal polarization, used to indicate the direction of the electric field component.

[0009] The electric field vector in the cross-polarization direction (assuming it is the y direction) is The mathematical representation of is as follows: .in, represents the amplitude in the cross-polarization direction; ω represents the angular frequency of the electromagnetic wave; t represents time; represents the initial phase angle of the cross-polarization direction; A unit vector representing the cross-polarization direction, which indicates the direction of the electric field component.

[0010] A transmitter can only emit (radiate) electromagnetic waves, and a receiver can only receive electromagnetic waves. Radar is a transmitter and receiver that can both emit and receive electromagnetic waves. Radar is used to detect targets and determine their spatial positions using radio methods. The target refers to a platform that can emit electromagnetic waves. A typical scenario is: the opponent's radar or transmitter is deployed on the target, which is the opponent's aircraft; our radar or receiver is deployed on a moving platform, which is our aircraft.

[0011] Assume that the other party's transmitter is deployed on the other party's aircraft (target), and our radar is used to detect the other party's aircraft. Since the flight attitude of the other party's aircraft changes in real time, the elliptically polarized wave emitted by the detection antenna of the other party's transmitter and the elliptically polarized wave received by the receiving antenna of our radar cannot be consistent at all times. There will be an angle α between the long axis of the elliptically polarized wave emitted by the detection antenna of the other party's transmitter and the elliptically polarized wave received by the receiving antenna of our radar, and the angle α also changes within a certain range as the flight attitude of the other party's aircraft changes.

[0012] When α=0, the polarization direction of the electromagnetic wave received by the receiving antenna of our radar is consistent with the polarization direction of the receiving antenna of our radar, which is called polarization matching. At this time, the polarization direction of the linear polarized wave output by the receiving antenna of our radar through the polarization converter (also called polarization converter) is consistent with the polarization direction required by the receiving waveguide, and the energy of the received wave can all enter the receiving system. Among them, the polarization converter is installed after the receiving antenna feed to convert the elliptically polarized wave into a linearly polarized wave. The receiving waveguide is installed after the polarization converter to perform wave type conversion so as to match the interface of the subsequent receiving unit (such as the receiving high-frequency head). The polarization direction required by the receiving waveguide refers to the specific polarization direction that the receiving waveguide can effectively receive when transmitting electromagnetic waves. In the waveguide, only the polarization component that matches the transmission direction of the waveguide can effectively enter and transmit, while the polarization component orthogonal to it will be reflected or attenuated.

[0013] When α≠0, the polarization direction of the electromagnetic wave received by the receiving antenna of our radar is inconsistent with the polarization direction of the receiving antenna of our radar, which is called incomplete polarization matching or polarization mismatch. At this time, the polarization direction of the linear polarization wave output by the receiving antenna of our radar through the polarization converter is not completely consistent with the polarization direction required by the receiving waveguide. At this time, the orthogonal component of the linear polarization wave output by the polarization converter will be reflected, and the received wave energy cannot enter the receiving system completely, causing loss, which is called polarization error loss, or polarization loss for short.

[0014] In existing radar simulation technology, the calculation of polarization loss is usually based on ideal conditions, while ignoring the various polarization effects that may exist in actual complex environments. This simplified calculation method may lead to a large deviation between the radar simulation results and the actual situation, thus affecting the design and optimization of the radar system.

[0015] In radar modeling, since the position, angle, and speed of an object are defined relative to a reference coordinate system, it is very important to clearly classify and convert coordinate systems. The following is a detailed introduction to various reference coordinate systems and their conversion methods.

[0016] First, the target coordinate system. The important function of radar is to observe the target. Usually the target motion (rigid body motion) characteristics are described in the target coordinate system. Figure 1 , the coordinate origin O of the target coordinate system is at the target mass center, the x-axis points to the east, the y-axis points to the north, and the z-axis points to the sky, satisfying the right-hand coordinate system. Please also refer to Figure 2 The three attitude angles of the target - roll angle, yaw angle, and pitch angle respectively represent the rotation angles around the X-axis, Y-axis, and Z-axis of the target coordinate system.

[0017] Second, the north-north-up coordinate system, also known as the east north up (ENU) coordinate system. This is a common ground coordinate system, with north, sky, and east as the X-axis, Y-axis, and Z-axis, respectively. Figure 3 The North Celestial East coordinate system can be set manually or a point can be randomly selected as the origin of the coordinate system. You only need to ensure that the North Celestial East coordinate system based on the same origin of the coordinate system is used.

[0018] Third, the platform coordinate system. If our radar is on a moving platform, such as an airplane, the motion characteristics of the moving platform are generally described in the platform coordinate system. The attitude angle of the platform coordinate system is defined and described in the North Celestial East coordinate system, so the platform coordinate system can be understood as a North Celestial East coordinate system with the origin of the coordinate system as the center of the moving platform.

[0019] Fourth, the antenna coordinate system. Take the center of the platform where the antenna is located as the coordinate origin of the antenna coordinate system, the X-axis is consistent with the direction of the antenna beam, the Y-axis is perpendicular to the beam direction and upward (vertical axis ratio axis), and the plane formed by the Z-axis and the X and Y axes satisfies the right-hand coordinate system (horizontal axis ratio axis). "Axis ratio axis" is a technical term, usually used to describe the directionality or contrast of a certain axis relative to another axis. "Vertical axis ratio axis" and "horizontal axis ratio axis" mean that in a specific coordinate system, in order to maintain directional consistency, the X-axis, Y-axis, and Z-axis are matched with specific directions of the antenna beam respectively.

[0020] If it is the antenna of our radar (or our receiver) and our radar (or our receiver) is on the ground, then the "center of the platform where the antenna is located" is the center point of our radar (or our receiver).

[0021] If it is the antenna of our radar (or our receiver), and our radar (or our receiver) is on a moving platform (such as an airplane), then the "center of the platform where the antenna is located" is the center point of the moving platform.

[0022] If it is the antenna of an enemy radar (or an enemy transmitter), and the enemy radar (or the enemy transmitter) is on the target (such as an aircraft), then the "center of the platform where the antenna is located" is the center point of the target.

[0023] There are three rotation processes of the right-handed coordinate system, namely, rotation around the X axis, rotation around the Y axis, and rotation around the Z axis. When the right-handed coordinate system rotates, it is usually stipulated that the counterclockwise rotation direction is the positive direction. According to the following three coordinate system rotation methods, the conversion of different reference coordinate systems can be realized, so as to unify the calculation under the North Celestial East coordinate system.

[0024] The rotation matrix of the three-dimensional rectangular right-handed coordinate system is rotated counterclockwise around the X-axis by an angle of θ. for .

[0025] The rotation matrix of the three-dimensional rectangular right-handed coordinate system rotating counterclockwise around the Y axis by an angle of θ and rotating around the y axis by an angle of θ for .

[0026] The rotation matrix of the three-dimensional rectangular right-handed coordinate system rotating counterclockwise around the Z axis by an angle of θ is for .

[0027] If you want to transform from the target coordinate system to the North Celestial East coordinate system, assuming that the azimuth, pitch, and roll angles in the target coordinate system are alpha, beta, and gamma respectively, you can define the rotation matrix G1. Among them, R x (-gamma) represents the rotation matrix of -gamma angle around the x-axis, R y (alpha) represents the rotation matrix of the angle alpha around the y-axis, R z (-beta) represents the rotation matrix of -beta angle around the z-axis. The target coordinate system can be converted to the North Celestial East coordinate system through the rotation matrix G1. The principle of converting the North Celestial East coordinate system to the target coordinate system is the same, which is the inverse process of the above process.

[0028] If you want to convert from the antenna coordinate system to the North Sky East coordinate system, assuming that the antenna beam azimuth angle in the antenna coordinate system (in the North Sky East coordinate system, it is the angle between the projection of the antenna beam on the horizontal plane, that is, the XOY plane, and the X-axis) is zeta, and the antenna beam elevation angle (in the North Sky East coordinate system, it is the angle between the antenna beam and the XOZ plane, that is, the inclination angle of the antenna beam in the vertical direction) is eta, then the rotation matrix G2 can be defined. Among them, R y (zeta) represents the rotation matrix of the zeta angle around the y-axis, R z (-eta) represents the rotation matrix of -eta angle around the z-axis. The antenna coordinate system can be transformed into the North Sky East coordinate system through the rotation matrix G2. The principle of transforming the North Sky East coordinate system into the antenna coordinate system is the same, which is the inverse process of the above process.

[0029] It can be found that the rotation matrix G2 does not contain the roll angle of the antenna beam in the antenna coordinate system. This is because the direction of the antenna beam can be completely described in the North-Sky-East coordinate system through the azimuth and elevation angles. In other words, the azimuth and elevation angles are sufficient to transform the antenna beam from the antenna coordinate system to the North-Sky-East coordinate system. The roll angle usually describes the rotation around the X-axis, which changes the lateral tilt (left and right tilt) of the antenna, but does not affect the pointing of the antenna beam in the horizontal and vertical planes. Therefore, the rotation around the X-axis does not change the direction of the antenna beam in the North-Sky-East coordinate system. Summary of the invention

[0030] The technical problem to be solved by the present application is: how to calculate the polarization loss more accurately, so as to improve the accuracy of radar digital simulation.

[0031] In order to solve the above technical problems, the present application proposes a radar simulation method based on dynamic polarization loss calculation, which includes the following steps. Step S1: According to the main polarization amplitude value A of the electromagnetic wave emitted by the other party's antenna m , main polarization phase value P m , cross-polarization amplitude value A c , cross-polarization phase value P c Calculate the first electric field vector of the electromagnetic wave emitted by the other party's antenna, described in the antenna coordinate system of the other party's antenna, considering only the polarization characteristics of the other party's antenna Step S2: According to the main polarization amplitude value AA of the electromagnetic wave emitted by our antenna m , main polarization phase value PP m , cross polarization amplitude value AA c , cross-polarization phase value PP c Calculate the second electric field vector of the electromagnetic wave emitted by our antenna, which is described in the antenna coordinate system of our antenna and only considers the polarization characteristics of our antenna The order of step S1 and step S2 can be either one before the other or performed simultaneously. Step S3: The first electric field vector Perform coordinate transformation from the antenna coordinate system of the other party's antenna to the North Sky East coordinate system, and obtain the third electric field vector of the electromagnetic wave emitted by the other party's antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of the other party's antenna. . Also the second electric field vector Perform coordinate transformation from the antenna coordinate system of our antenna to the North Sky East coordinate system, and obtain the fourth electric field vector of the electromagnetic wave emitted by our antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of our antenna. Step S4: For the third electric field vector and the fourth electric field vector Perform a dot product calculation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North Celestial East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and our antenna. ; Dynamic polarization loss is also obtained.

[0032] Furthermore, in step S1, the antenna coordinate system of the other party's antenna is based on the center of the platform where the other party's antenna is located as the coordinate origin, the X-axis is consistent with the antenna beam direction, the Y-axis is perpendicular to the beam direction and upward, and the plane formed by the Z-axis and the X- and Y-axes satisfies the right-hand coordinate system. In step S2, the antenna coordinate system of our antenna is based on the center of the platform where our antenna is located as the coordinate origin, the X-axis is consistent with the antenna beam direction, the Y-axis is perpendicular to the beam direction and upward, and the plane formed by the Z-axis and the X- and Y-axes satisfies the right-hand coordinate system.

[0033] Furthermore, in step S1, firstly, according to the main polarization amplitude value A of the electromagnetic wave emitted by the other party's antenna m and the main polarization phase value P m Get the main polarization direction electric field vector of the electromagnetic wave emitted by the other party's antenna ; ; Where ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the main polarization direction of the electromagnetic wave emitted by the other party's antenna. It is also based on the cross-polarization amplitude value A of the electromagnetic wave emitted by the other party's antenna. c and the cross-polarization phase value P c Get the cross-polarization electric field vector of the electromagnetic wave emitted by the other party's antenna ; ; Where ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the cross-polarization direction of the electromagnetic wave emitted by the other antenna. and Perform vector summation to obtain the first electric field vector of the electromagnetic wave emitted by the other party's antenna ; .

[0034] Furthermore, in step S2, firstly, according to the main polarization amplitude value AA of the electromagnetic wave emitted by our antenna m and the main polarization phase value PP m Get the main polarization direction electric field vector of the electromagnetic wave emitted by our antenna ; ; Where ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the main polarization direction of the electromagnetic wave emitted by our antenna. It is also based on the cross-polarization amplitude value AA of the electromagnetic wave emitted by our antenna. c and the cross-polarization phase value PP c Get the cross-polarization electric field vector of the electromagnetic wave emitted by our antenna ; ; Where ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the cross-polarization direction of the electromagnetic wave emitted by our antenna. and Perform vector summation to obtain the second electric field vector of the electromagnetic wave emitted by our antenna ; .

[0035] Furthermore, in step S3, the north, sky and east coordinate system are respectively the X-axis, the Y-axis and the Z-axis.

[0036] Furthermore, in step S3, the antenna coordinate system is converted to the north-east coordinate system. Assuming that the azimuth angle of the antenna beam in the antenna coordinate system is zeta and the elevation angle of the antenna beam is eta, a rotation matrix G2 is defined; ;in, The rotation matrix representing the rotation angle zeta around the y-axis, The rotation matrix represents the rotation of -eta angle around the z-axis; the antenna coordinate system is converted to the north-east coordinate system through the rotation matrix G2. The rotation matrix represents the rotation of the three-dimensional rectangular right-handed coordinate system around the Y-axis by an angle of θ counterclockwise for The rotation matrix of the three-dimensional rectangular right-handed coordinate system rotating counterclockwise around the Z axis by an angle of θ for .

[0037] Furthermore, in step S4, firstly, the fourth electric field vector Decomposed into the electric field component in the main polarization direction and the cross-polarization electric field component , then calculate and ,in Represents the dot product calculation, and we get The amplitude in the main polarization direction and the initial phase angle of the main polarization direction , The amplitude in the cross-polarization direction and the initial phase angle in the cross-polarization direction . . . . .in, Indicates dot product calculation; the abs() function is used to calculate the modulus of a complex number, that is, the absolute value of a complex number; the angle() function is used to calculate the phase angle of a complex number, and the value range is [-π,π]. Then the electric field vector of the main polarization direction of the electromagnetic wave received by our antenna is calculated, which is described in the North Celestial East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna. ; ;in, It represents the unit vector of the main polarization direction of the electromagnetic wave received by our antenna, described in the North-Sky-East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and our own antenna. It also calculates the electric field vector of the cross-polarization direction of the electromagnetic wave received by our antenna, described in the North-Sky-East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and our own antenna. ; ;in, It represents the unit vector of the cross-polarization direction of the electromagnetic wave received by our antenna, described in the North Celestial East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and our antenna. and Perform vector summation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North-East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna. ; .

[0038] Furthermore, in step S4, the dynamic polarization loss , the unit is watt; where the abs() function is used to calculate the modulus of a complex number, that is, the absolute value of a complex number; or, dynamic polarization loss , the unit is dB; the calculated dynamic polarization loss is also described in the North-East coordinate system, taking into account the mutual influence of the polarization characteristics of the opponent's antenna and the polarization characteristics of our antenna.

[0039] Furthermore, the dynamic polarization loss calculated in step S4 is Participate in the subsequent calculations of radar simulation; the receiving power of our radar = the transmitting power of our radar + the transmitting antenna gain of the opponent's radar + the receiving antenna gain of our radar - dynamic polarization loss - Free space path loss - Loss due to weather interference.

[0040] The present application also proposes a radar simulation device based on dynamic polarization loss calculation, including an opponent antenna polarization characteristic description unit, a our antenna polarization characteristic description unit, a coordinate conversion unit, and a description unit for the mutual influence of the polarization characteristics of both antennas. The opponent antenna polarization characteristic description unit is used to calculate the main polarization amplitude value A of the electromagnetic wave emitted by the known opponent antenna. m , main polarization phase value P m , cross-polarization amplitude value A c , cross-polarization phase value P c Calculate the first electric field vector of the electromagnetic wave emitted by the other party's antenna, described in the antenna coordinate system of the other party's antenna, considering only the polarization characteristics of the other party's antenna The said own antenna polarization characteristic description unit is used to calculate the main polarization amplitude value AA of the electromagnetic wave emitted by the known own antenna. m , main polarization phase value PP m , cross polarization amplitude value AA c , cross-polarization phase value PP c Calculate the second electric field vector of the electromagnetic wave emitted by our antenna, which is described in the antenna coordinate system of our antenna and only considers the polarization characteristics of our antenna The coordinate conversion unit is used to convert the first electric field vector Perform coordinate transformation from the antenna coordinate system of the other party's antenna to the North Sky East coordinate system, and obtain the third electric field vector of the electromagnetic wave emitted by the other party's antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of the other party's antenna. ; It is also used to convert the second electric field vector Perform coordinate transformation from the antenna coordinate system of our antenna to the North Sky East coordinate system, and obtain the fourth electric field vector of the electromagnetic wave emitted by our antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of our antenna. The mutual influence description unit of the polarization characteristics of the two antennas is used to describe the third electric field vector and the fourth electric field vector Perform a dot product calculation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North Celestial East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and our antenna. ; Dynamic polarization loss is also obtained.

[0041] The technical effect achieved by this application is: fully considering the actual environment where our antenna and the opponent's antenna may be in motion, calculating more accurate dynamic polarization loss, and applying it to the radar digital simulation platform can improve the radar simulation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the origin and three axes of the target coordinate system.

[0043] Figure 2 It is a schematic diagram of the three attitude angles of the target coordinate system.

[0044] Figure 3 It is a schematic diagram of the North Celestial East coordinate system.

[0045] Figure 4 It is a flow chart of the radar simulation method based on dynamic polarization loss calculation proposed in this application.

[0046] Figure 5 It is a structural schematic diagram of a radar simulation device based on dynamic polarization loss calculation proposed in this application.

[0047] Explanation of the reference numerals in the figure: a polarization characteristic description unit 1 of the other party's antenna, a polarization characteristic description unit 2 of our antenna, a coordinate conversion unit 3, and a mutual influence description unit 4 of the polarization characteristics of both parties' antennas. DETAILED DESCRIPTION

[0048] See also Figure 4 The radar simulation method based on dynamic polarization loss calculation proposed in this application includes the following steps.

[0049] Step S1: The antenna of the enemy radar or the enemy transmitter carried by the target (for example, the enemy aircraft) is called the enemy antenna. The main polarization amplitude value A of the electromagnetic wave emitted by the enemy antenna is known. m , main polarization phase value P m , cross-polarization amplitude value A c , cross-polarization phase value P c These four physical quantities are described in the antenna coordinate system of the other party's antenna, reflecting the polarization characteristics of the other party's antenna. From this, the first electric field vector of the electromagnetic wave emitted by the other party's antenna, which is described in the antenna coordinate system of the other party's antenna and only considers the polarization characteristics of the other party's antenna, is calculated. The first electric field vector The mutual influence between the polarization characteristics of the opponent's antenna and our own antenna is not taken into account.

[0050] First, according to the main polarization amplitude value A of the electromagnetic wave emitted by the other party's antenna m and the main polarization phase value P m Get the main polarization direction electric field vector of the electromagnetic wave emitted by the other party's antenna . . Among them, ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector of the axis ratio axis θ, that is, the unit vector of the main polarization direction of the electromagnetic wave emitted by the other antenna. * indicates multiplication, the same below.

[0051] Also based on the cross-polarization amplitude value A of the electromagnetic wave emitted by the other party's antenna c and the cross-polarization phase value P c Get the cross-polarization electric field vector of the electromagnetic wave emitted by the other party's antenna . . Among them, ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the axis-to-axis φ is also the unit vector representing the cross-polarization direction of the electromagnetic wave emitted by the other antenna.

[0052] In polarization analysis, elliptically polarized waves can usually be decomposed into two mutually orthogonal components. This step uses the unit vectors θ and φ in two orthogonal directions. and They represent the main polarization component and cross polarization component of the electromagnetic wave emitted by the other party's antenna. The θ direction represents the main polarization direction of the electromagnetic wave emitted by the other party's antenna, and the φ direction represents the cross polarization direction of the electromagnetic wave emitted by the other party's antenna. The purpose of decomposing the electromagnetic wave emitted by the other party's antenna in this way is to facilitate the analysis of the impact of different polarization directions on signal reception and matching.

[0053] Then and Perform vector summation to obtain the first electric field vector of the electromagnetic wave emitted by the other party's antenna ; .

[0054] Step S2: The antenna of our radar is called our antenna. The main polarization amplitude value AA of the electromagnetic wave emitted by our antenna is known. m , main polarization phase value PP m , cross polarization amplitude value AA c , cross-polarization phase value PP c These four physical quantities are described in the antenna coordinate system of our antenna, reflecting the polarization characteristics of our antenna. From this, the second electric field vector of the electromagnetic wave emitted by our antenna, which is described in the antenna coordinate system of our antenna and only considers the polarization characteristics of our antenna, is calculated. The second electric field vector The mutual influence between the polarization characteristics of our antenna and the polarization characteristics of the opponent's antenna is not taken into account.

[0055] First, according to the main polarization amplitude value AA of the electromagnetic wave emitted by our antenna m and the main polarization phase value PP m Get the main polarization direction electric field vector of the electromagnetic wave emitted by our antenna . . Among them, ω represents the angular frequency of the electromagnetic wave; t represents time; Indicates the axis ratio The unit vector of the main polarization direction of the electromagnetic wave emitted by our antenna.

[0056] Also based on the cross-polarization amplitude value AA of the electromagnetic wave emitted by our antenna c and the cross-polarization phase value PP c Get the cross-polarization electric field vector of the electromagnetic wave emitted by our antenna . . Among them, ω represents the angular frequency of the electromagnetic wave; t represents time; Represents the unit vector of the axis ratio axis η, that is, the unit vector of the cross-polarization direction of the electromagnetic wave emitted by our antenna.

[0057] This step uses and η are two unit vectors in orthogonal directions and They respectively represent the main polarization component and cross-polarization component of the electromagnetic wave emitted by our antenna. The direction represents the main polarization direction of the electromagnetic wave emitted by our antenna, and the direction η represents the cross-polarization direction of the electromagnetic wave emitted by our antenna. The purpose of decomposing the electromagnetic wave emitted by our antenna in this way is to facilitate the analysis of the impact of different polarization directions on signal reception and matching.

[0058] Then and Perform vector summation to obtain the second electric field vector of the electromagnetic wave emitted by our antenna ; .

[0059] There is no strict restriction on the order of step S1 and step S2, and they can be performed one before the other or simultaneously.

[0060] Step S3: The first electric field vector Perform coordinate transformation from the antenna coordinate system of the other party's antenna to the North Sky East coordinate system, and obtain the third electric field vector of the electromagnetic wave emitted by the other party's antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of the other party's antenna. .

[0061] Also the second electric field vector Perform coordinate transformation from the antenna coordinate system of our antenna to the North Sky East coordinate system, and obtain the fourth electric field vector of the electromagnetic wave emitted by our antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of our antenna. .

[0062] The purpose of this coordinate system conversion is to project the electromagnetic waves emitted by the other party's antenna and our antenna into the same coordinate system.

[0063] Step S4: For the third electric field vector and the fourth electric field vector Perform a dot product calculation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North Celestial East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and our antenna. ; Dynamic polarization loss is also obtained.

[0064] First, the fourth electric field vector Decomposed into the electric field component in the main polarization direction and the cross-polarization electric field component , then calculate and ,in Represents the dot product calculation, and we get The amplitude in the main polarization direction and the initial phase angle of the main polarization direction , The amplitude in the cross-polarization direction and the initial phase angle in the cross-polarization direction .

[0065] .

[0066] .

[0067] .

[0068] .

[0069] in, Indicates dot product calculation; the abs() function is used to calculate the modulus of a complex number, that is, the absolute value of a complex number; the angle() function is used to calculate the phase angle of a complex number, and the value range is [-π,π]. The physical meaning of dot product calculation is to make the polarization characteristics of the other party's antenna interact with the polarization characteristics of our antenna. The four physical quantities obtained are described in the North Celestial East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna.

[0070] Then, the electric field vector of the main polarization direction (x direction) of the electromagnetic wave received by our antenna is calculated, which is described in the North-East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna. . .in, It represents the unit vector of the main polarization direction of the electromagnetic wave received by our antenna, described in the North-East coordinate system, taking into account the mutual influence of the polarization characteristics of the opponent's antenna and our antenna. It is used to indicate the direction of the electric field component.

[0071] The electric field vector of the cross-polarization direction (y direction) of the electromagnetic wave received by our antenna, described in the North-East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna, is also calculated. . .in, The unit vector representing the cross-polarization direction of the electromagnetic wave received by our antenna, described in the North-East coordinate system, taking into account the mutual influence of the polarization characteristics of the opponent's antenna and our antenna, is used to indicate the direction of the electric field component.

[0072] Then and Perform vector summation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North-East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna. . .

[0073] Because the opponent's antenna is deployed on the target, and our antenna is deployed on the ground or on a moving platform, the position and posture between the opponent's antenna and our antenna are different at all times, which will cause the polarization loss to be different at all times, so this is dynamic polarization loss. , in watts. Or, dynamic polarization loss , the unit is dB. and To calculate the dynamic polarization loss, and It is described in the North-Sky-East coordinate system, taking into account the mutual influence of the polarization characteristics of the opponent's antenna and the polarization characteristics of our antenna. Therefore, the calculated dynamic polarization loss is also described in the North-Sky-East coordinate system, taking into account the mutual influence of the polarization characteristics of the opponent's antenna and the polarization characteristics of our antenna.

[0074] The dynamic polarization loss calculated in step S4 is Participate in the subsequent calculations of radar simulation, for example, the receiving power of our radar = the transmitting power of our radar + the transmitting antenna gain of the opponent's radar + the receiving antenna gain of our radar - - Free space path loss - Loss due to weather interference.

[0075] See also Figure 5 The radar simulation device based on dynamic polarization loss calculation proposed in this application includes an opponent antenna polarization characteristic description unit 1, an own antenna polarization characteristic description unit 2, a coordinate conversion unit 3, and a mutual influence description unit 4 of the polarization characteristics of both antennas. Figure 5 The device shown corresponds to Figure 4 The method shown.

[0076] The other party antenna polarization characteristic description unit 1 is used to determine the main polarization amplitude value A of the electromagnetic wave emitted by the other party antenna according to the known main polarization amplitude value A of the electromagnetic wave emitted by the other party antenna. m , main polarization phase value P m , cross-polarization amplitude value A c , cross-polarization phase value P c Calculate the first electric field vector of the electromagnetic wave emitted by the other party's antenna, described in the antenna coordinate system of the other party's antenna, considering only the polarization characteristics of the other party's antenna .

[0077] The said own antenna polarization characteristic description unit 2 is used to calculate the main polarization amplitude value AA of the electromagnetic wave emitted by the known own antenna m , main polarization phase value PP m , cross polarization amplitude value AA c , cross-polarization phase value PP c Calculate the second electric field vector of the electromagnetic wave emitted by our antenna, which is described in the antenna coordinate system of our antenna and only considers the polarization characteristics of our antenna .

[0078] The coordinate conversion unit 3 is used to convert the first electric field vector Perform coordinate transformation from the antenna coordinate system of the other party's antenna to the North Sky East coordinate system, and obtain the third electric field vector of the electromagnetic wave emitted by the other party's antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of the other party's antenna. ; It is also used to convert the second electric field vector Perform coordinate transformation from the antenna coordinate system of our antenna to the North Sky East coordinate system, and obtain the fourth electric field vector of the electromagnetic wave emitted by our antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of our antenna. .

[0079] The mutual influence description unit 4 of the polarization characteristics of the two antennas is used to describe the third electric field vector and the fourth electric field vector Perform a dot product calculation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North Celestial East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and our antenna. ; Dynamic polarization loss is also obtained.

[0080] Compared with the prior art, the present application has the following beneficial effects.

[0081] First, the existing polarization loss calculation method usually uses the polarization of the two antennas in a static state to refer to the polarization of the entire process. This application accurately models the different azimuth, pitch, and roll angles of the two antennas in motion, and calculates the momentary changes of the dynamic polarization loss caused by the relative motion of the two antennas as accurately as possible, thereby reducing the deviation between the radar simulation results and the actual situation.

[0082] Second, existing radar simulations usually use a platform coordinate system instead of an antenna coordinate system. In this application, the platform coordinate system and the antenna coordinate system are independent of each other, and are further divided into the antenna coordinate system of our antenna and the antenna coordinate system of the opponent's antenna. The independent distinction and conversion of the antenna coordinate system further improves the calculation accuracy of the polarization loss, thereby improving the radar simulation accuracy.

[0083] Third, the method of the present application is used in the radar digital simulation platform to set the parameters and polarization mode of the antennas of both parties, and to calculate the dynamic polarization loss. The calculation results are used in subsequent calculations, and the output of beam alignment under different conditions (for example, by adjusting the pitch angle, azimuth angle, roll angle, scanning angle of both antennas, etc.) is tested.

[0084] Experiments show that when the beam of the other party's antenna is aligned with the beam of our antenna, if the vertical axis ratio axis and the horizontal axis ratio axis of the two beams are aligned respectively, the received main polarization amplitude is the superposition of the two main polarization amplitudes, and the received secondary polarization amplitude is the superposition of the two cross-polarization amplitudes. If the vertical axis ratio axis and the horizontal axis ratio axis of the two beams are cross-aligned, the received main polarization amplitude is the superposition of the main polarization amplitude of our receiving device antenna and the cross-polarization of the other party's antenna, and the received secondary polarization amplitude is the superposition of the secondary polarization amplitude of our receiving device antenna and the main polarization of the other party's antenna.

[0085] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should all be included in the protection scope of the present application.

Claims

1. A radar simulation method based on dynamic polarization loss calculation, characterized in that: The method comprises the following steps: Step S1: According to the main polarization amplitude value A of the electromagnetic wave emitted by the other party's antenna m , main polarization phase value P m , cross-polarization amplitude value A c , cross-polarization phase value P c Calculate the first electric field vector of the electromagnetic wave emitted by the other party's antenna, described in the antenna coordinate system of the other party's antenna, considering only the polarization characteristics of the other party's antenna ; Step S2: According to the main polarization amplitude value AA of the electromagnetic wave emitted by our antenna m , main polarization phase value PP m , cross polarization amplitude value AA c , cross-polarization phase value PP c Calculate the second electric field vector of the electromagnetic wave emitted by our antenna, which is described in the antenna coordinate system of our antenna and only considers the polarization characteristics of our antenna ; The order of step S1 and step S2 may be either first or second, or they may be performed simultaneously; Step S3: The first electric field vector Perform coordinate transformation from the antenna coordinate system of the other party's antenna to the North Sky East coordinate system, and obtain the third electric field vector of the electromagnetic wave emitted by the other party's antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of the other party's antenna. ; Also the second electric field vector Perform coordinate transformation from the antenna coordinate system of our antenna to the North Sky East coordinate system, and obtain the fourth electric field vector of the electromagnetic wave emitted by our antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of our antenna. ; Step S4: For the third electric field vector and the fourth electric field vector Perform a dot product calculation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North Celestial East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and our antenna. ; Dynamic polarization loss is also obtained; Dynamic polarization loss , the unit is watt; where the abs() function is used to calculate the modulus of a complex number, that is, the absolute value of a complex number; or, dynamic polarization loss , the unit is dB; The calculated dynamic polarization loss is also described in the North-East coordinate system, taking into account the mutual influence of the polarization characteristics of the opponent's antenna and the polarization characteristics of our antenna.

2. The radar simulation method based on dynamic polarization loss calculation according to claim 1 is characterized in that: In step S1, the antenna coordinate system of the other party's antenna takes the center of the platform where the other party's antenna is located as the coordinate origin, the X-axis is consistent with the antenna beam direction, the Y-axis is perpendicular to the beam direction and points upward, and the plane formed by the Z-axis and the X- and Y-axes satisfies the right-hand coordinate system; In step S2, the antenna coordinate system of our antenna takes the center of the platform where our antenna is located as the coordinate origin, the X-axis is consistent with the antenna beam direction, the Y-axis is perpendicular to the beam direction and points upward, and the plane formed by the Z-axis and the X- and Y-axes satisfies the right-hand coordinate system.

3. The radar simulation method based on dynamic polarization loss calculation according to claim 1 is characterized in that: In step S1, first, according to the main polarization amplitude value A of the electromagnetic wave emitted by the other party's antenna, m and the main polarization phase value P m Get the main polarization direction electric field vector of the electromagnetic wave emitted by the other party's antenna ; ; Where ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the main polarization direction of the electromagnetic wave emitted by the other party's antenna; Also based on the cross-polarization amplitude value A of the electromagnetic wave emitted by the other party's antenna c and the cross-polarization phase value P c Get the cross-polarization electric field vector of the electromagnetic wave emitted by the other party's antenna ; ; Where ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the cross-polarization direction of the electromagnetic wave emitted by the other party's antenna; Then and Perform vector summation to obtain the first electric field vector of the electromagnetic wave emitted by the other party's antenna ; .

4. The radar simulation method based on dynamic polarization loss calculation according to claim 1 is characterized in that: In step S2, firstly, according to the main polarization amplitude value AA of the electromagnetic wave emitted by our antenna, m and the main polarization phase value PP m Get the main polarization direction electric field vector of the electromagnetic wave emitted by our antenna ; ; Where ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the main polarization direction of the electromagnetic wave emitted by our antenna; Also based on the cross-polarization amplitude value AA of the electromagnetic wave emitted by our antenna c and the cross-polarization phase value PP c Get the cross-polarization electric field vector of the electromagnetic wave emitted by our antenna ; ; Where ω represents the angular frequency of the electromagnetic wave; t represents time; The unit vector representing the cross-polarization direction of the electromagnetic wave emitted by our antenna; Then and Perform vector summation to obtain the second electric field vector of the electromagnetic wave emitted by our antenna ; .

5. The radar simulation method based on dynamic polarization loss calculation according to claim 1 is characterized in that: In step S3, the north, sky and east coordinate system are respectively the X-axis, the Y-axis and the Z-axis of the north, the sky and the east.

6. The radar simulation method based on dynamic polarization loss calculation according to claim 1 is characterized in that: In step S3, the antenna coordinate system is converted to the north-east coordinate system. Assuming that the antenna beam azimuth angle in the antenna coordinate system is zeta and the antenna beam elevation angle is eta, the rotation matrix G2 is defined; G2=R y (zeta)*R z (-eta); where R y (zeta) represents the rotation matrix of the zeta angle around the y-axis, R z (-eta) represents the rotation matrix of -eta angle around the z-axis; the antenna coordinate system is transformed into the North Celestial East coordinate system through the rotation matrix G2; The rotation matrix R of the three-dimensional rectangular right-handed coordinate system rotating counterclockwise around the Y axis by an angle θ y (θ) is ; The rotation matrix R of the three-dimensional rectangular right-handed coordinate system rotating counterclockwise around the Z axis by an angle θ z (θ) is .

7. The radar simulation method based on dynamic polarization loss calculation according to claim 1 is characterized in that: In step S4, firstly, the fourth electric field vector Decomposed into the electric field component in the main polarization direction and the cross-polarization electric field component , then calculate and ,in Represents the dot product calculation, and we get The amplitude in the main polarization direction and the initial phase angle of the main polarization direction , The amplitude in the cross-polarization direction and the initial phase angle in the cross-polarization direction ; ； ； ； ； in, Indicates dot product calculation; the abs() function is used to calculate the modulus of a complex number, that is, the absolute value of a complex number; the angle() function is used to calculate the phase angle of a complex number, and the value range is [-π,π]; Then, the electric field vector of the main polarization direction of the electromagnetic wave received by our antenna is calculated, which is described in the North Celestial East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna. ; ;in, It represents the unit vector of the main polarization direction of the electromagnetic wave received by our antenna, described in the North Celestial East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna; The electric field vector of the cross-polarization direction of the electromagnetic wave received by our antenna, which is described in the North-East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and our antenna, is also calculated. ; ;in, The unit vector representing the cross-polarization direction of the electromagnetic wave received by our antenna, described in the North Celestial East coordinate system, taking into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna; Then and Perform vector summation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North-East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and the polarization characteristics of our antenna. ; .

8. The radar simulation method based on dynamic polarization loss calculation according to claim 1 is characterized in that: The dynamic polarization loss M' calculated in step S4 participates in the subsequent calculation of radar simulation; the receiving power of our radar = the transmitting power of our radar + the transmitting antenna gain of the other radar + the receiving antenna gain of our radar - dynamic polarization loss M' - free space path loss - loss due to weather interference.

9. A radar simulation device based on dynamic polarization loss calculation, characterized in that: It includes a description unit for the polarization characteristics of the other party's antenna, a description unit for the polarization characteristics of our antenna, a coordinate conversion unit, and a description unit for the mutual influence of the polarization characteristics of the two parties' antennas; The other party antenna polarization characteristic description unit is used to determine the main polarization amplitude value A of the electromagnetic wave emitted by the other party antenna according to the known m , main polarization phase value P m , cross-polarization amplitude value A c , cross-polarization phase value P c Calculate the first electric field vector of the electromagnetic wave emitted by the other party's antenna, described in the antenna coordinate system of the other party's antenna, considering only the polarization characteristics of the other party's antenna ; The polarization characteristic description unit of our antenna is used to calculate the main polarization amplitude value AA of the electromagnetic wave emitted by our antenna according to the known main polarization amplitude value AA of the electromagnetic wave emitted by our antenna. m , main polarization phase value PP m , cross polarization amplitude value AA c , cross-polarization phase value PP c Calculate the second electric field vector of the electromagnetic wave emitted by our antenna, which is described in the antenna coordinate system of our antenna and only considers the polarization characteristics of our antenna ; The coordinate conversion unit is used to convert the first electric field vector Perform coordinate transformation from the antenna coordinate system of the other party's antenna to the North Sky East coordinate system, and obtain the third electric field vector of the electromagnetic wave emitted by the other party's antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of the other party's antenna. ; It is also used to convert the second electric field vector Perform coordinate transformation from the antenna coordinate system of our antenna to the North Sky East coordinate system, and obtain the fourth electric field vector of the electromagnetic wave emitted by our antenna described in the North Sky East coordinate system, which only considers the polarization characteristics of our antenna. ; The mutual influence description unit of the polarization characteristics of the two antennas is used to describe the third electric field vector and the fourth electric field vector Perform a dot product calculation to obtain the fifth electric field vector of the electromagnetic wave received by our antenna, which is described in the North Celestial East coordinate system and takes into account the mutual influence of the polarization characteristics of the other party's antenna and our antenna. ; Dynamic polarization loss is also obtained; Dynamic polarization loss , the unit is watt; where the abs() function is used to calculate the modulus of a complex number, that is, the absolute value of a complex number; or, dynamic polarization loss , the unit is dB; the calculated dynamic polarization loss is also described in the North-East coordinate system, taking into account the mutual influence of the polarization characteristics of the opponent's antenna and the polarization characteristics of our antenna.

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