Outdoor ground object environment electromagnetic characteristic test method

Abstract

The present application relates to the technical field of electromagnetic characteristics, in particular to a kind of outdoor ground object environment electromagnetic characteristic test method.The design method includes: according to antenna directional diagram, the angle of antenna B, E face is determined;Through antenna directional diagram, select angle energy ratio, isometric to determine test echo energy, reflect narrowing measurement area, make antenna near-field spherical wave tend to planar wave measurement data;Through antenna B, E face directional diagram and antenna pitch angle, construct radiation space cone model;The radiation space cone model is formed by innumerable section ellipses distributed along its axis;The axis length of the radiation space cone model is used to represent the section ellipse;The line segment of the intersection of multiple section ellipses and ground is integrated, and the irradiation area of radiation on ground is obtained;Electromagnetic measurement data and the irradiation area are compared, and the ground object backscattering coefficient is obtained.The present application embodiment provides a kind of outdoor ground object environment electromagnetic characteristic test method, and ground object environment electromagnetic characteristics can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic characteristics, in particular to an outdoor ground object environment electromagnetic characteristic testing method. BACKGROUND

[0002] The electromagnetic scattering characteristics of a target represent the electromagnetic properties of the target itself, and the application in electromagnetic countermeasures is becoming mature and widespread. Therefore, the study of a target is inevitably affected by its environment, such as the sky, the ocean and the ground environment. The ground environment has a large number of different ground objects and a complex ground surface. Therefore, by sampling and measuring different ground objects and calculating the electromagnetic scattering backscattering coefficient per unit area, the electromagnetic characteristics of the ground objects can be effectively represented to support the related research of ground targets.

[0003] At the same time, the ground object sample has a large area and is difficult to be shaped independently from the outdoor environment. The antenna radiation range cannot be observed by the naked eye, and the radiation area becomes a key problem for obtaining the electromagnetic backscattering coefficient of the ground object. SUMMARY

[0004] The present application provides an outdoor ground object environment electromagnetic characteristic testing method, which can obtain the electromagnetic characteristics of the ground object environment.

[0005] The present application provides an outdoor ground object environment electromagnetic characteristic testing method, which includes:

[0006] The angles of the antenna B and E surfaces are determined according to the antenna directional diagram;

[0007] The angular energy proportion is selected through the antenna directional diagram, the test echo energy is determined in a proportional manner, the measurement area is narrowed, and the antenna near-field spherical wave tends to be a plane wave measurement data;

[0008] The radiation space cone model is constructed through the directional diagrams of the antenna B and E surfaces and the antenna tilt angle. The radiation space cone model is formed by a large number of cross-sectional ellipses distributed along the axis thereof;

[0009] The cross-sectional ellipses are represented by the axis length of the radiation space cone model;

[0010] The line segments intersected by the ground are integrated, and the irradiation area of the radiation on the ground is obtained;

[0011] The electromagnetic measurement data and the irradiation area are compared, and the ground object backscattering coefficient is obtained.

[0012] In a possible design, the cross-sectional ellipses are represented by the axis length of the radiation space cone model through the following formula:

[0013]

[0014] wherein, taking the straight line where the long axis of the section ellipse is located as the x-axis and the short axis as the y-axis, x and y are respectively the coordinates of the points forming the ellipse, L is the length of the axis of the radiation space cone model, and ∠E and ∠B are respectively the included angles between the axis and the E plane and the B plane.

[0015] In a possible design, the integral of the line segments where the plurality of section ellipses and the ground intersect, to obtain the irradiation area of the radiation on the ground, comprises:

[0016] The integral of the line segments where the plurality of section ellipses and the ground intersect, the plurality of axis lengths of which are not greater than the line-ground distance, to obtain a first area; wherein the line-ground distance is the distance between the starting point of the axis of the radiation space cone model and the intersection point where the axis is incident on the ground;

[0017] The integral of the line segments where the plurality of section ellipses and the ground intersect, the plurality of axis lengths of which are not less than the line-ground distance, to obtain a second area;

[0018] According to the first area and the second area, the irradiation area of the radiation on the ground is obtained.

[0019] In a possible design, the first area is:

[0020]

[0021] wherein S1 is the first area, ∠C is the included angle between the lower boundary line of the radiation space cone model and the ground, h is the antenna height, and ΔL1 is the distance between the current axis and the axis corresponding to the minimum section ellipse intersecting the ground.

[0022] In a possible design, the second area is:

[0023]

[0024] wherein S2 is the second area, ∠D is the included angle between the upper boundary line of the radiation space cone model and the ground, and ΔL2 is the distance by which the current axis changes relative to the line-ground distance.

[0025] In a possible design, the irradiation area is calculated by the following formula:

[0026]

[0027] wherein, is the overlapping part in the first area and the second area.

[0028] Compared with the prior art, the present application has at least the following beneficial effects:

[0029] The radiation area is obtained by integrating the line segments of the intersection part of the ground and the multiple tangent section ellipses, the electromagnetic measurement data is compared with the radiation area, and the ground object backscattering coefficient is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0031] Figure 1 is a side view of the position relationship between a radiation space cone model and a ground object sample provided by the embodiment of the present application;

[0032] Figure 2 is a top view of the position relationship between a radiation space cone model and a ground object sample provided by the embodiment of the present application;

[0033] Figure 3a is an antenna directional diagram cumulative curve provided by the embodiment of the present application;

[0034] Figure 3b is an antenna directional diagram cumulative curve slope growth change diagram provided by the embodiment of the present application;

[0035] Figure 4 is a first area calculation auxiliary diagram provided by the embodiment of the present application;

[0036] Figure 5 is a second area calculation auxiliary diagram provided by the embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0038] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the terms "first", "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance; unless otherwise specified or stated, the term "multiple" refers to two or more; the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "connection" can be fixed connection, or detachable connection, or integrally connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0039] In the description of the present specification, it should be understood that the "upper", "lower" and the like described in the embodiments of the present application are described with the angle shown in the drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it should also be understood that when referring to one element connected to another element "on" or "below", it can be directly connected to another element "on" or "below", or indirectly connected to another element "on" or "below" through an intermediate element.

[0040] As shown in Figure 1 and Figure 2 The embodiments of the present application provide an outdoor ground object environment electromagnetic characteristic test method, comprising:

[0041] The angles of the antenna B and E surfaces are determined according to the antenna directional diagram;

[0042] The angular energy proportion is selected through the antenna directional diagram, the test echo energy is determined in equal proportion, the measurement area is narrowed, and the antenna near-field spherical wave tends to be planar wave measurement data;

[0043] The radiation space cone model is constructed through the directional diagrams of the antenna B and E surfaces and the antenna tilt angle; the radiation space cone model is formed by numerous cross-sectional ellipses distributed along the axis thereof;

[0044] The cross-sectional ellipses are represented by the axis length of the radiation space cone model;

[0045] The line segments intersected by the multiple cross-sectional ellipses and the ground are integrated to obtain the irradiation area of the radiation on the ground;

[0046] The electromagnetic measurement data and the irradiation area are compared to obtain the ground object backscattering coefficient.

[0047] In the present application, through the integration of the line segments intersected by the ground and the multiple cross-sectional ellipses, the radiation area can be obtained, and the electromagnetic measurement data and the irradiation area are compared to obtain the ground object backscattering coefficient.

[0048] Specifically, a ground object environment meeting the test requirements is selected, an antenna with a suitable directional diagram is selected according to a ground object area and a test height, and an antenna irradiation area meets a target area. The application takes a radar system as a core to form an RCS measurement system. After the high-altitude measurement system is built, the equipment is started and preheated until the system is stable, and relevant frequency bands and polarizations are set. After the equipment is completed, the antenna and related equipment are lifted to the test height, the antenna pitch angle and roll angle are adjusted according to the test requirements, and the test is completed.

[0049] It should be noted that an antenna with a suitable directional diagram is selected according to a ground object area and a test height, and an antenna irradiation area meets a target area. As can be seen from FIG. 3, the energy of the antenna directional diagram tends to a constant with the angle accumulation. It can be seen that the echo beyond a certain angle does not affect the main measurement. The appropriate irradiation angle is determined by judging the B and E plane angles of the antenna.

[0050] Meanwhile, for relatively flat, uniform and strong scattering ground object samples, the angle energy ratio of the antenna directional diagram can be selected to determine the test echo energy in proportion, and the test data reflecting the narrowing of the measurement area to make the antenna near-field spherical wave tend to be a plane wave

[0051] In some embodiments of the application, the use of the axis length of the radiation space cone model to represent the section ellipse is realized by the following formula:

[0052]

[0053] wherein the straight line where the long axis of the section ellipse is located is the x axis, and the short axis is the y axis, x and y are the coordinates of the points forming the ellipse, L is the axis length of the radiation space cone model, and ∠E and ∠B are the angles between the axis and the E plane and the B plane, respectively.

[0054] In some embodiments of the application, the line segments intersecting the ground and formed by a plurality of section ellipses are integrated to obtain the irradiation area on the ground, including:

[0055] The line segments intersecting the ground and formed by a plurality of section ellipses with axis lengths not greater than the line-ground distance are integrated to obtain a first area; wherein the line-ground distance is the distance between the starting point of the axis of the radiation space cone model and the intersection point of the axis on the ground.

[0056] The line segments intersecting the ground and formed by a plurality of section ellipses with axis lengths not less than the line-ground distance are integrated to obtain a second area.

[0057] According to the first area and the second area, the irradiation area on the ground is obtained.

[0058] In the embodiment, the first area and the second area are obtained by integrating the intersection line segments, and the intersection line segments obtained by the intersection of the two side surface ellipses and the ground are located on the two sides of the long axis of the surface ellipse, so that the intersection line segments need to be integrated in parts;

[0059] The integral start point of the first area is the intersection line segment of the minimum surface ellipse intersecting with the ground, that is, the tangent point, and the integral end point is the intersection line segment of the surface ellipse with the axis as the line distance and the ground. The integral method is to express the surface ellipse under different axis lengths by using the ellipse formula, then substitute the straight line formula into the ellipse formula of the surface ellipse, and solve the x coordinate, that is, half the length of the intersection line segment, that is, the length of the intersection line segment, that is, the chord length of the surface ellipse; the integral start point of the second area is the intersection line segment of the surface ellipse with the axis as the line distance and the ground (the integral end point of the first area), and the integral end point is the intersection line segment of the maximum surface ellipse intersecting with the ground. Similarly, the integral method is the same as that of the first area, that is, to express the surface ellipse under different axis lengths by using the ellipse formula, then substitute the straight line formula into the ellipse formula of the surface ellipse, and solve the x coordinate, that is, half the length of the intersection line segment, that is, the length of the intersection line segment, that is, the chord length of the surface ellipse.

[0060] In some embodiments of the application, the first area is:

[0061]

[0062] Wherein, S1 is the first area, ∠C is the angle between the lower boundary line of the radiation space cone model and the ground, h is the antenna height, and ΔL1 is the distance between the current axis and the axis corresponding to the minimum surface ellipse intersecting with the ground.

[0063] Specifically, referring to Figure 4 , the first area is obtained by integrating the intersection line segments of the plurality of surface ellipses with lengths not greater than the line distance and the ground, and the method comprises the following steps:

[0064] constructing an expression of the minimum surface ellipse intersecting with the ground;

[0065]

[0066]

[0067]

[0068] Wherein, L2 is the length of the axis corresponding to the minimum surface ellipse intersecting with the ground, L4 is the minor axis of the minimum surface ellipse, L5 is the major axis of the minimum surface ellipse, ∠C is the angle between the lower boundary line of the radiation space cone model and the ground, and h is the antenna height.

[0069] The first formula is used to express the multiple cutting surface ellipses in which the lengths of the multiple axes are not greater than the distance from the line;

[0070]

[0071] wherein, ΔL1 is the distance of the current axis relative to the axis of the minimum cutting surface ellipse, Δa is the long axis of the current cutting surface ellipse, Δb is the short axis of the current cutting surface ellipse, Δx and Δy are the coordinates of the point of the current cutting surface ellipse respectively;

[0072] The second formula is used to express the straight line intersecting the current cutting surface ellipse on the ground;

[0073]

[0074] wherein, ∠A is the angle between the axis and the ground;

[0075] The second formula is substituted into the first formula to obtain the length of the first line segment of the intersection between the straight line and the cutting surface ellipse;

[0076]

[0077]

[0078] The first area is obtained by integrating the first line segment;

[0079]

[0080] In some embodiments of the present application, the second area is:

[0081]

[0082] wherein, S2 is the second area, ∠D is the angle between the upper boundary line of the radiation space cone model and the ground, and ΔL2 is the distance of the current axis relative to the distance from the line.

[0083] In some embodiments of the present application, the irradiation area is calculated by the following formula:

[0084]

[0085] wherein, is the overlapping part of the first area and the second area.

[0086] Please refer to Figure 5 and the same calculation method as described above, that is, the calculation formula of the second area can be obtained.

[0087] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for testing electromagnetic characteristics of an outdoor ground object environment, characterized by, The method comprises the following steps: determining the angles of the antenna B and E planes according to the antenna directional diagram; selecting the angular energy proportion through the antenna directional diagram, determining the test echo energy in equal proportion, reflecting the narrowing of the measurement area, and making the antenna near-field spherical wave tend to be planar wave measurement data; constructing a radiation space cone model through the directional diagrams of the antenna B and E planes and the antenna tilt angle; the radiation space cone model is formed by a large number of cross-section ellipses distributed along the axis of the model; representing the cross-section ellipses by the axis length of the radiation space cone model; integrating the line segments intersected by the cross-section ellipses and the ground to obtain the illumination area on the ground; comparing the electromagnetic measurement data and the illumination area to obtain the ground object backscattering coefficient.

2. The test method of claim 1, wherein, The representation of the cross-section ellipses by the axis length of the radiation space cone model is realized through the following formula: wherein the straight line where the long axis of the cross-section ellipse is located is taken as the x axis, the short axis is taken as the y axis, x and y are the coordinates of the points forming the ellipse, L is the axis length of the radiation space cone model, and ∠E and ∠B are the included angles of the axis and the E plane and the B plane respectively.

3. The test method of claim 2, wherein, The integration of the line segments intersected by the cross-section ellipses and the ground to obtain the illumination area on the ground comprises the following steps: integrating the line segments intersected by the cross-section ellipses and the ground to obtain the first area; wherein the line-ground distance is the distance between the starting point of the axis of the radiation space cone model and the intersection point of the axis on the ground; integrating the line segments intersected by the cross-section ellipses and the ground to obtain the second area; wherein the line-ground distance is the distance between the starting point of the axis of the radiation space cone model and the intersection point of the axis on the ground; obtaining the illumination area on the ground according to the first area and the second area.

4. The test method of claim 3, wherein, The first area is: wherein S1 is the first area, ∠C is the included angle between the lower boundary line of the radiation space cone model and the ground, h is the antenna height, ΔL1 is the distance between the current axis and the axis corresponding to the minimum cross-section ellipse intersecting the ground, and ∠A is the included angle between the axis and the ground.

5. The test method of claim 4, wherein, The second area is: wherein S2 is the second area, ∠D is the included angle between the upper boundary line of the radiation space cone model and the ground, and ΔL2 is the distance by which the current axis changes relative to the line-ground distance.

6. The test method of claim 5, wherein, The illumination area is calculated through the following formula: wherein is the portion of the first area and the second area that overlap.

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