Background
In recent years, simulation and test are indispensable links in the development process of modern electronic systems. The field test can obtain the most realistic relevant performance parameters of the electronic system to be tested, and find out some possible problems, and has the highest experimental value. However, the outfield test is generally complicated, involves many aspects, and is thus expensive. In order to better improve the cost performance, a semi-physical radio frequency simulation is often required to be carried out in a microwave darkroom before an external field test is carried out on an electronic system such as a guide head. The semi-physical radio frequency simulation is also called physical in-loop simulation, namely, in a simulation loop, the seeker to be tested exists in physical form and in actual working state. The semi-physical radio frequency simulation has the simulation physical introduced into the simulation loop, so that the simulation result is very similar to the outfield test. However, the cost is greatly reduced. Therefore, the method has higher cost performance. Therefore, the semi-physical radio frequency simulation plays an important role in the research and development of electronic systems such as a guide head, and the semi-physical radio frequency simulation system has become an essential research and development equipment in some countries.
The semi-physical radio frequency simulation system is generally composed of a radiation array, a turntable, a computer control system and the like. In a microwave darkroom, there is a relatively large antenna array on which a plurality of radiating elements are arranged in order. The outer edge of the array surface is generally circular, regular hexagonal or rectangular, etc. The antennas are generally aligned in a regular pattern, and adjacent antennas are generally triangular. The whole antenna array surface faces one turntable, and electronic systems such as a guide head to be tested and the like can be arranged on the turntable. When the semi-physical radio frequency simulation experiment is carried out, every adjacent three radiating units can form a triplet so as to simulate the echo of the point target to be simulated in the triplet triangle. This Triple (TUA) structure was proposed earlier by boeing, and has been adopted by semi-physical radio frequency simulation laboratories in various countries and regions of the world. The three radiating elements of the triplet generally form a regular triangle. The rationality is that better unit utilization can be obtained. The three radiating units can feed simultaneously, electromagnetic waves radiated by the three radiating units are overlapped at the guide head, and the energy flow direction of a composite field at the guide head is exactly the same as the echo energy flow direction of a target of a point to be simulated in real environment space at the guide head. The energy flow direction of the synthesized field is a function of the feed amplitude of the three radiating elements, so that the synthesized electromagnetic energy flow direction can be adjusted and changed by adjusting the feed amplitude of the three radiating elements, thereby achieving the purpose of simulating echoes of point targets in different directions at different moments. On the basis, the simulation of the radio frequency environment under the whole ballistic motion is realized.
In triplet simulation, there is always an important problem, namely the triplet near field effect. Because there is an important formula in the feed coefficient calculation of the triplet, the amplitude center of gravity formula. The formula may represent the direction of the point target at the simulation as a linear combination of the directions of the three radiating elements of the triplet. This is in and out of the actual simulated non-punctuation direction, which is the triplet near field error. The existing method for solving the triplet near field error generally comprises an iteration method and a fitting method. The simulated angle error is obtained by experimental measurements or strict electromagnetic calculations, with which the change of the feed coefficient (which is proportional to the feed amplitude) is driven, so that the simulated angle error is reduced to an acceptable level by iteration, which is used because no strict analytical function expression between the feed coefficient and the simulated direction is obtained. In addition, existing triplet near field correction techniques do not take into account the effects of seeker spin.
Thus, the disadvantages of the prior art are mainly: the feed coefficient of the triplet in the semi-physical radio frequency simulation cannot be rapidly determined, and the universality is poor.
Disclosure of Invention
The embodiment of the invention provides a method for determining the feed coefficient of a triplet in semi-physical radio frequency simulation, which can accurately and rapidly determine the feed coefficient of the triplet in the semi-physical radio frequency simulation. The technical scheme is as follows:
the embodiment of the invention provides a method for determining a triplet feed coefficient in semi-physical radio frequency simulation, which comprises the following steps:
establishing a mathematical coordinate system for the simulation scene;
establishing an azimuth information equivalence equation contained in a field on the port surface of the guide head antenna in simulation according to the established mathematical coordinate system of the simulation scene;
deducing a nonlinear interpolation equation of the triplet simulation according to the established bit information equivalence equation to replace an amplitude gravity center formula;
and determining the feed coefficient of the semi-physical radio frequency simulation triplet according to the derived nonlinear interpolation equation of the triplet simulation.
Further, the establishing a mathematical coordinate system for the simulation scene includes:
establishing an xyz rectangular coordinate system by taking the center point of the antenna port surface of the seeker as a coordinate origin O, wherein two orthogonal base line directions of the antenna array of the seeker are respectively the x direction and the y direction by taking the antenna port surface of the seeker as the xy surface, and the ith spoke in the tripletThe coordinates of the shooting unit are (x i ,y i ,z i ),z i >>x i ,y i I=1, 2,3, the coordinates of the point object are (x, y, z), z>>x, y, the offset angle of the point target and the ith radiating element in the triplet with respect to the z-axis in the x-direction and the y-direction is:
wherein, psi is x 、ψ y The offset angles, ψ, of the point target in the x-direction and y-direction, respectively, relative to the z-axis xi 、ψ yi The offset angles of the ith radiating element of the triplet in the x-direction and the y-direction relative to the z-axis respectively, asin (·) representing an arcsine function;
the position of the turntable is taken as an origin, and the directions of the x axis and the y axis are respectively psi
x Shaft, psi
y The direction of the axis and takes the central point P of the triplet as a pole, and is parallel to the psi
x The direction is the polar axis direction, and the polar angle of the ith radiation unit in the triplet is denoted as alpha
i The polar angle of the point target is alpha, and the polar diameter is psi
r Triplet edge length opening angle is psi
l The angular domain distance from each radiation unit to the P point is
Further, the establishing the azimuth information equivalence equation of the field on the opening surface of the guide head antenna in the simulation according to the established mathematical coordinate system of the simulation scene comprises the following steps:
assuming four antenna units on the aperture surface of the seeker, the seeker has different equivalent phase center points, wherein two antenna units form an interferometer in the x direction, the other two antenna units form an interferometer in the y direction, and the interference base line lengths in the x direction and the y direction are L respectively x 、L y ;
Calibrating the phase of each radiation unit of the triplet according to the distance from each radiation unit to the original point O, so that the fields of each radiation unit at the point O are in phase;
if the antennas 2 and 4 are in the x direction, the radiation fields of the three radiation units of the triplets received by the antennas 2 and 4 are respectively:
wherein A is a constant coefficient, j in exp (·) is an imaginary unit, s 2 、s 4 Representing the radiation fields of three radiation units of the triplets received by the antennas 2 and 4, C i The feed coefficient of the ith radiating element, k is the wave vector, k is the wave number, r i0 Vector line segment from the ith radiation unit of the triplet to the origin point O, r ij Vector line segments from the ith element to the jth antenna of the triplet;
the radiation fields of the point targets received by the antennas 2 and 4 are respectively:
wherein s is t2 、s t4 Radiation fields r representing the point targets received by the antennas 2, 4, respectively t0 Vector line segment from point target to point of origin O, r tj For the point target to the j th dayVector line segments of the line;
according to the fact that the azimuth information is contained in the phase information, and the phase information of the field on the antenna port surface of the receiving antenna in the simulation environment is equal to the phase information of the antenna port surface field in the actual environment, the method comprises the following steps of:
wherein arg (. Cndot.) represents the principal value of the argument.
Further, deriving a non-linear interpolation equation of the triplet simulation according to the established bit information equivalence equation to replace the amplitude barycenter equation comprises:
for a pair of
Solving to obtain a nonlinear interpolation equation:
by using the approximation of sin function under small angle, the method obtains
Expression in polar coordinate system:
and similarly, obtaining:
further, the determining the feed coefficient of the semi-physical radio frequency simulation triplet according to the derived nonlinear interpolation equation of the triplet simulation comprises:
according to
Is->
Obtaining an analytic expression of the feed coefficient;
and according to the analysis expression of the feeding coefficient, the feeding coefficient of the semi-physical radio frequency simulation triplet avoiding the near field error of the triplet is obtained.
Further, the analytical expression of the feed coefficient is:
further, after determining the feed coefficient of the semi-physical radio frequency simulation triplet according to the derived triplet simulated nonlinear interpolation equation, the method further comprises:
and determining the optimal estimation of the analysis expression result of the feed coefficient when the spin gesture of the seeker is unknown, and obtaining the optimal estimation value of the feed coefficient when the spin gesture of the seeker is unknown.
Further, the determining the optimal estimation of the analysis expression result of the feed coefficient when the spin gesture of the seeker is unknown, and obtaining the optimal estimation value of the feed coefficient when the spin gesture of the seeker is unknown includes:
let L x =L y Record kL x /2=kL y And (2) carrying out mathematical expectation on random distribution of spin postures of the seeker by using the analysis expression result of the feed coefficient to obtain that the spin postures of the seeker are in [0,2 pi ]]C when uniformly distributed in i Is a mathematical expectation of:
wherein Γ is a shorthand symbol,
is algebraic quantityExpressed as:
wherein,,
the best estimate of the feed coefficient when the seeker spin attitude is unknown is represented.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
1. when the gesture of the seeker is known, the feeding coefficient avoiding the triplet near field error can be obtained;
2. when the gesture of the seeker is unknown, an optimal feed coefficient estimated value can be obtained;
3. the method for improving the three-tuple feed coefficient in the semi-physical radio frequency simulation provides a quicker and more effective three-tuple feed coefficient method for better improving the semi-physical radio frequency simulation precision, and can accurately and quickly determine the feed coefficient of the three-tuple in the semi-physical radio frequency simulation.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, an embodiment of the present invention provides a method for determining a triplet feed coefficient in a semi-physical radio frequency simulation, including:
s101, establishing a mathematical coordinate system for a simulation scene;
s102, establishing an azimuth information equivalence equation contained in a field on the port surface of a pilot head antenna in simulation according to a mathematical coordinate system of the established simulation scene;
s103, deducing a nonlinear interpolation equation of the triplet simulation according to the established bit information equivalence equation to replace an amplitude gravity center formula;
s104, determining the feed coefficient of the semi-physical radio frequency simulation triplet according to the deduced nonlinear interpolation equation of the triplet simulation.
The method for determining the triple feed coefficient in the semi-physical radio frequency simulation establishes a mathematical coordinate system for a simulation scene; establishing an azimuth information equivalence equation contained in a field on the port surface of the guide head antenna in simulation according to the established mathematical coordinate system of the simulation scene; deducing a nonlinear interpolation equation of the triplet simulation according to the established bit information equivalence equation to replace an amplitude gravity center formula; and determining the feed coefficient of the semi-physical radio frequency simulation triplet according to the derived nonlinear interpolation equation of the triplet simulation. Therefore, the feeding coefficient of the triplet in the semi-physical radio frequency simulation can be accurately and rapidly determined, and the obtained feeding coefficient is the feeding coefficient avoiding the near field error of the triplet, so that the influence of the near field error of the triplet can be overcome, and the accuracy requirement of the semi-physical radio frequency simulation test can be met.
In a specific embodiment of the method for determining a triplet feed coefficient in a semi-physical radio frequency simulation, the establishing a mathematical coordinate system for a simulation scene further includes:
establishing an xyz rectangular coordinate system by taking the center point of the antenna port surface of the seeker as a coordinate origin O, wherein two orthogonal bases of the antenna array of the seeker are taken as xy surfaces by taking the antenna port surface of the seekerThe line directions are the x direction and the y direction respectively, and the coordinate of the ith radiating element in the triplet is (x i ,y i ,z i ),z i >>x i ,y i I=1, 2,3, the coordinates of the point object are (x, y, z), z>>x, y, the offset angle of the point target and the ith radiating element in the triplet with respect to the z-axis in the x-direction and the y-direction is:
wherein, psi is x 、ψ y The offset angles, ψ, of the point target in the x-direction and y-direction, respectively, relative to the z-axis x 、ψ y The direction in which the point target is located is indicated as shown in fig. 2; psi phi type xi 、ψ yi Offset angles, ψ, of the ith radiating element of the triplet in x-direction, y-direction, respectively, relative to the z-axis xi 、ψ yi Indicating the direction in which each radiating element of the triplet is located, asin (·) representing an arcsine function;
let psi be examined
x 、ψ
y The plane of the angle domain takes the position of the turntable as the origin and takes the directions of the x axis and the y axis as psi respectively
x Shaft, psi
y The direction of the axis and takes the central point P of the triplet as a pole, and is parallel to the psi
x The direction is the polar axis direction, and the polar angle of the ith radiation unit in the triplet is denoted as alpha
i The polar angle of the point target is alpha, and the polar diameter is psi
r Triplet edge length opening angle is psi
l The angular domain distance from each radiation unit to the P point is
As shown in fig. 3.
In a specific embodiment of the method for determining a triplet feed coefficient in semi-physical radio frequency simulation, further, the establishing an azimuth information equivalence equation of field implications on an antenna port surface of a pilot head in simulation according to an established mathematical coordinate system of a simulation scene includes:
assuming four antenna units on the aperture surface of the seeker, the seeker has different equivalent phase center points, wherein two antenna units form an interferometer in the x direction, the other two antenna units form an interferometer in the y direction, and the interference base line lengths in the x direction and the y direction are L respectively x 、L y As shown in fig. 4;
calibrating the phase of each radiation unit of the triplet according to the distance from each radiation unit to the original point O, so that the fields (specifically, radiation fields) of each radiation unit at the point O are in phase; wherein each radiation unit in the triplet is in the far field of the caliber of the seeker;
if the antennas 2 and 4 are in the x direction, the radiation fields of the three radiation units of the triplets received by the antennas 2 and 4 are respectively:
wherein A is a constant coefficient, j in exp (·) is an imaginary unit, s 2 、s 4 Representing the radiation fields of three radiation units of the triplets received by the antennas 2 and 4, C i The feed coefficient of the ith radiating element (which is proportional to the feed amplitude), k is the wave vector, k is the wave number, r i0 Vector line segment from the ith radiation unit of the triplet to the origin point O, r ij Vector line segment from the ith element to the jth antenna of the triplet;
The radiation fields of the point targets received by the antennas 2 and 4 are respectively:
wherein s is t2 、s t4 Radiation fields r representing the point targets received by the antennas 2, 4, respectively t0 Vector line segment from point target to point of origin O, r tj Vector line segment from point target to j-th antenna;
according to the fact that the azimuth information is contained in the phase information, and the phase information of the field on the antenna port surface of the receiving antenna in the simulation environment is equal to the phase information of the antenna port surface field in the actual environment, the method comprises the following steps of:
wherein arg (. Cndot.) represents the principal value of the argument.
In a specific embodiment of the foregoing method for determining a triplet feed coefficient in a semi-physical radio frequency simulation, further, deriving a nonlinear interpolation equation of the triplet simulation according to the established bit information equivalence equation, to replace the amplitude barycenter equation includes:
for formula (9):
solving to obtain a nonlinear interpolation equation:
by using the approximation of sin function under small angle, the method obtains
The expression under the polar coordinate system of fig. 3:
and similarly, obtaining:
wherein the small angle is an angle smaller than a preset threshold.
In a specific embodiment of the foregoing method for determining a feeding coefficient of a triplet in a semi-physical radio frequency simulation, further, determining a feeding coefficient of a semi-physical radio frequency simulation triplet according to a derived nonlinear interpolation equation of the triplet simulation includes:
from equations (11) and (12), the analytical expression for the feed coefficient is obtained as:
parameters k, L x .L y ,ψ s ,ψ r ,α,α i Substituting into the formula (13), the feed coefficient of the triplet in the semi-physical radio frequency simulation, which avoids the near field error of the triplet, can be obtained.
In a specific embodiment of the method for determining a triplet feed coefficient in a semi-physical radio frequency simulation, further, after determining a feed coefficient of a semi-physical radio frequency simulation triplet according to a derived nonlinear interpolation equation of the triplet simulation, the method further includes:
determining the seeker spin attitude is unknown (i.e., α i Unknown) and obtaining an optimal estimated value of the feed coefficient when the spin attitude of the seeker is unknown, wherein the method specifically comprises the following steps of:
let L x =L y Record kL x /2=kL y Using the result of equation (13) to make mathematical expectation on random distribution of the spin gesture of the seeker, the spin gesture of the seeker is obtained when [0,2 pi ]]C when uniformly distributed in i Is a mathematical expectation of:
wherein Γ is a shorthand symbol,
the number of generations, expressed as:
parameters k, L
x .L
y ,ψ
s ,ψ
r ,α-α
i Substituting into the blocks (14) and (15) to calculate to obtain the spin gesture of the seeker as [0,2 pi ]]C when uniformly distributed in
i Mathematical expectation of (a)
Namely: the best estimate of the feed coefficient when the seeker spin attitude is unknown.
In the present embodiment, although alpha, alpha i Is unknown, but alpha-alpha i Is known and unchanged.
In the present embodiment, when the seeker posture is unknown, the optimum feed coefficient estimation value can be obtained according to the equations (14), (15).
In summary, aiming at the problems of more iteration times, poor universality and the like, the embodiment of the invention provides a method for determining the triplet feed coefficient in semi-physical radio frequency simulation, which at least has the following advantages:
1. when the gesture of the seeker is known, the feeding coefficient avoiding the triplet near field error can be obtained;
2. when the gesture of the seeker is unknown, an optimal feed coefficient estimated value can be obtained;
3. the method for improving the three-tuple feed coefficient in the semi-physical radio frequency simulation provides a quicker and more effective three-tuple feed coefficient method for better improving the semi-physical radio frequency simulation precision, and can accurately and quickly determine the feed coefficient of the three-tuple in the semi-physical radio frequency simulation.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.