Method for testing electromagnetic characteristics of outdoor ground object environment

Abstract

The invention relates to the technical field of electromagnetic characteristics, in particular to an outdoor ground object environment electromagnetic characteristic testing method. The design method comprises the following steps: determining angles of H and E surfaces of an antenna according to an antenna pattern; the method comprises the following steps: selecting an angular domain energy ratio through an antenna pattern, determining test echo energy in equal proportion, reflecting a narrowed measurement area, and enabling an antenna near-field spherical wave to tend to plane wave measurement data; constructing a radiation space cone model through the directional diagrams of the H and E surfaces of the antenna and the pitch angle of the antenna; the radiation space cone model is formed by countless tangent plane ellipses distributed along the axis of the radiation space cone model; representing the tangent plane ellipse by using the axis length of the radiation space cone model; integrating a plurality of intersecting line segments of the tangent plane ellipses and the ground to obtain an irradiation area of radiation on the ground; and comparing the electromagnetic measurement data with the irradiation area to obtain the ground object backscattering coefficient. The embodiment of the invention provides an outdoor ground object environment electromagnetic characteristic test method, which can obtain ground object environment electromagnetic characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic characteristics, and in particular to a method for testing the electromagnetic characteristics of an outdoor ground object environment. Background Art

[0002] The electromagnetic scattering characteristics of a target characterize the electromagnetic properties of the target itself, and their application in electromagnetic countermeasures is becoming increasingly mature and widespread. Therefore, when studying a target, it is inevitably affected by its environment, such as the sky, the ocean, and the earth. Compared with other environments, the earth has a wide variety of objects and complex surface conditions. Therefore, by sampling and measuring different objects and calculating their electromagnetic scattering back coefficients per unit area to characterize their electromagnetic characteristics, it can effectively support research related to ground targets.

[0003] At the same time, the area of ​​ground object samples is large, and it is difficult to form them independently of the outdoor environment. The radiation range of the antenna cannot be observed with the naked eye, and the area of ​​its radiation area becomes the key issue in obtaining the electromagnetic backscattering coefficient of the ground object. Summary of the invention

[0004] The embodiment of the present invention provides a method for testing the electromagnetic characteristics of an outdoor ground object environment, which can obtain the electromagnetic characteristics of the ground object environment.

[0005] The embodiment of the present invention provides a method for testing electromagnetic characteristics of an outdoor object environment, comprising:

[0006] Determine the angles of the antenna H and E planes based on the antenna pattern;

[0007] The angular energy ratio is selected through the antenna pattern, and the test echo energy is determined in proportion, which reflects the narrowing of the measurement area and makes the antenna near-field spherical wave approach the plane wave measurement data;

[0008] A radiation space cone model is constructed by using the directional patterns of the antenna H and E planes and the antenna elevation angle; the radiation space cone model is formed by countless sectional ellipses distributed along its axis;

[0009] The section ellipse is represented by the axis length of the radiation space cone model;

[0010] Integrate the line segments where the plurality of tangent ellipses intersect the ground to obtain the irradiated area on the ground;

[0011] The electromagnetic measurement data is compared with the irradiated area to obtain the backscattering coefficient of the ground object.

[0012] In a possible design, the use of the axis length of the radiation space cone model to represent the section ellipse is achieved by the following formula:

[0013]

[0014] Among them, the straight line where the major axis of the section ellipse is located is the x-axis, the minor 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, ∠H and ∠B are the angles between the axis and the H surface and the B surface respectively.

[0015] In a possible design, integrating the line segments where the plurality of tangent ellipses intersect the ground to obtain the irradiation area of ​​the radiation on the ground includes:

[0016] Integrate the line segments where the multiple tangent ellipses and the ground intersect, where the lengths of multiple axis lines are not greater than the line-to-ground distance, to obtain a first area; wherein the line-to-ground distance is the distance between the axis of the radiation space cone model from the starting point to the intersection point where the axis is incident on the ground;

[0017] Integrate the line segments where the plurality of tangent ellipses and the ground intersect, where the plurality of axis lengths are located and the lengths of which are not less than the line-to-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] Among them, S1 is the first area, ∠C is the angle between the lower boundary 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 tangent ellipse intersecting the ground.

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

[0023]

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

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

[0026]

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

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

[0029] By integrating the line segments of the intersection of the ground and a plurality of section ellipses, the radiation area can be obtained, and the backscattering coefficient of the ground object can be obtained by comparing the electromagnetic measurement data with the irradiated area. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

[0033] Figure 3a is an antenna pattern accumulation curve diagram provided by an embodiment of the present invention;

[0034] Figure 3b It is a graph showing the growth change of the slope of an antenna pattern accumulation curve provided by an embodiment of the present invention;

[0035] Figure 4 A first area calculation auxiliary graph provided by an embodiment of the present invention;

[0036] Figure 5 A second area calculation auxiliary graph provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected" and "fixed" should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0040] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a method for testing electromagnetic characteristics of an outdoor object environment, comprising:

[0041] Determine the angles of the antenna H and E planes based on the antenna pattern;

[0042] The angular energy ratio is selected through the antenna pattern, and the test echo energy is determined in proportion, which reflects the narrowing of the measurement area and makes the antenna near-field spherical wave approach the plane wave measurement data;

[0043] The radiation space cone model is constructed by the directional patterns of the antenna H and E planes and the antenna elevation angle; the radiation space cone model is formed by countless sectional ellipses distributed along its axis;

[0044] The section ellipse is represented by the axis length of the radiation space cone model;

[0045] Integrate the line segments where multiple tangent ellipses intersect the ground to obtain the irradiation area on the ground;

[0046] By comparing the electromagnetic measurement data with the irradiated area, the backscatter coefficient of the ground object can be obtained.

[0047] In the present invention, the radiation area can be obtained by integrating the line segments of the intersection of the ground and a plurality of section ellipses, and the backscattering coefficient of the ground object can be obtained by comparing the electromagnetic measurement data with the irradiated area.

[0048] Specifically, a terrain environment that meets the test requirements is selected, and an antenna with a suitable directional pattern is selected according to the terrain area and the test height, so that the antenna irradiation area meets the target area. The present invention builds an RCS measurement system with a radar system as the core. After the high-altitude measurement system is built, the equipment is turned on and preheated until the system is stable, and the relevant frequency band and polarization settings are performed. After the equipment is warmed up, the antenna and other 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, according to the terrain area and the test height, an antenna with a suitable radiation pattern is selected so that the antenna irradiation area meets the target area. Figure 3 shows that the energy of the antenna radiation pattern approaches a constant as the angle accumulates. It can be seen that the echo no longer affects the main measurement after exceeding a certain angle. The appropriate irradiation angle is determined by the angles of the antenna H and E planes.

[0050] At the same time, for relatively flat, uniform and non-strong scattering ground samples, the angular energy ratio can be selected through the antenna pattern, and the test echo energy can be determined proportionally, reflecting the test data of narrowing the measurement area to make the antenna near-field spherical wave tend to the plane wave.

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

[0052]

[0053] Among them, the straight line where the major axis of the section ellipse is located is the x-axis, the minor 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, ∠H and ∠B are the axis and the angles between the H surface and the B surface, respectively.

[0054] In some embodiments of the present invention, the line segments where a plurality of tangent ellipses intersect the ground are integrated to obtain the irradiation area of ​​the radiation on the ground, including:

[0055] The first area is obtained by integrating the line segments where the multiple tangent ellipses where the lengths of the multiple axis lines are located and the ground intersect, where the line-ground distance is the distance between the axis line of the radiation space cone model from the starting point to the intersection point where the axis line is incident on the ground;

[0056] The second area is obtained by integrating the line segments where the multiple tangent ellipses where the multiple axis lengths are located and the ground intersect, where the lengths are not less than the line-ground distance;

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

[0058] In this embodiment, the first area and the second area are obtained by integrating the intersecting line segments. The tangent plane ellipse where the line-to-ground distance is located is used as the standard. The line segments obtained by the intersection of the tangent plane ellipse on both sides and the ground are located on both sides of the major axis of the tangent plane ellipse. Therefore, it is necessary to integrate the intersecting line segments in parts.

[0059] Among them, the integral starting point of the first area is: the intersection line segment obtained by the minimum tangent ellipse intersecting the ground, that is, the tangent point, and the integral end point is: the intersection line segment between the tangent ellipse and the ground when the axis is the line-to-ground distance. The integral method is to use the ellipse formula to express the tangent ellipse under different axis lengths, and then substitute the straight line formula into the ellipse formula of the tangent ellipse to find the coordinate of x, which 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 tangent ellipse; the integral starting point of the second area is: the intersection line segment between the tangent ellipse and the ground when the axis is the line-to-ground distance (the integral end point of the first area), and the integral end point is the intersection line segment obtained by the maximum tangent ellipse intersecting the ground. Similarly, the integral method is the same as the first area, which is to use the ellipse formula to express the tangent ellipse under different axis lengths, and then substitute the straight line formula into the ellipse formula of the tangent ellipse to find the coordinate of x, which 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 tangent ellipse.

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

[0061]

[0062] Wherein, S1 is the first area, ∠C is the angle between the lower boundary 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 tangent ellipse intersecting the ground.

[0063] For details, please refer to Figure 4 , the step of integrating the line segments where the plurality of tangent ellipses and the ground intersect and where the plurality of axis lengths of which are not greater than the line-to-ground distance are located to obtain the first area comprises:

[0064] Constructing an expression for the smallest tangent ellipse that just intersects the ground;

[0065]

[0066]

[0067]

[0068] Wherein, L2 is the length of the axis corresponding to the smallest tangent ellipse intersecting the ground, L4 is the short axis of the smallest tangent ellipse, L5 is the long axis of the smallest tangent ellipse, ∠C is the angle between the lower boundary of the radiation space cone model and the ground, and h is the antenna height;

[0069] Using a first formula to express a plurality of said section ellipses where the lengths of the plurality of axis lines are located and the lengths of the axis lines are not greater than the line-to-ground distance;

[0070] Δa=(L2+ΔL1)*tanE

[0071] Δb=(L2+ΔL1)*tanB

[0072]

[0073] Wherein, ΔL1 is the distance of the current axis relative to the axis corresponding to the minimum section ellipse, Δa is the major axis of the current section ellipse, Δb is the minor axis of the current section ellipse, and Δx and Δy are the coordinates of the points of the current section ellipse respectively;

[0074] The second formula is used to express the straight line on the ground that intersects the current section ellipse;

[0075]

[0076] Among them, ∠A is the angle between the axis and the ground;

[0077] Substituting the second formula into the first formula, the length of the first line segment of the intersection of the straight line and the tangent ellipse is obtained;

[0078]

[0079] Integrate the first line segment to obtain a first area;

[0080]

[0081] In some embodiments of the present invention, the second area is:

[0082]

[0083] Wherein, S2 is the second area, ∠D is the angle between the upper boundary of the radiation space cone model and the ground, and ΔL2 is the distance of the current axis relative to the line-to-ground distance change.

[0084] In some embodiments of the present invention, the irradiation area is calculated by the following formula:

[0085]

[0086] in, It is the overlapping part of the first area and the second area.

[0087] Please refer to Figure 5 The calculation formula for the second area can be obtained by using the same calculation method as above.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the electromagnetic characteristics of an outdoor object environment, characterized in that: include: Determine the angles of the antenna H and E planes based on the antenna pattern; The angular energy ratio is selected through the antenna pattern, and the test echo energy is determined in proportion, which reflects the narrowing of the measurement area and makes the antenna near-field spherical wave approach the plane wave measurement data; A radiation space cone model is constructed by using the directional patterns of the antenna H and E planes and the antenna elevation angle; the radiation space cone model is formed by countless sectional ellipses distributed along its axis; The section ellipse is represented by the axis length of the radiation space cone model; Integrate the line segments where the plurality of tangent ellipses intersect the ground to obtain the irradiated area on the ground; The electromagnetic measurement data is compared with the irradiated area to obtain the backscattering coefficient of the ground object.

2. The design method according to claim 1, characterized in that: The use of the axis length of the radiation space cone model to represent the section ellipse is achieved by the following formula: Among them, the straight line where the major axis of the section ellipse is located is the x-axis, the minor 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, ∠H and ∠B are the angles between the axis and the H surface and the B surface respectively.

3. The design method according to claim 2, characterized in that: The step of integrating the line segments where the plurality of tangent ellipses intersect the ground to obtain the irradiated area of ​​the radiation on the ground comprises: Integrate the line segments where the multiple tangent ellipses and the ground intersect, where the lengths of multiple axis lines are not greater than the line-to-ground distance, to obtain a first area; wherein the line-to-ground distance is the distance between the axis of the radiation space cone model from the starting point to the intersection point where the axis is incident on the ground; Integrate the line segments where the plurality of tangent ellipses and the ground intersect, where the plurality of axis lengths are located and the lengths of which are not less than the line-to-ground distance, to obtain a second area; According to the first area and the second area, the irradiation area of ​​the radiation on the ground is obtained.

4. The design method according to claim 3, characterized in that: The first area is: Among them, S1 is the first area, ∠C is the angle between the lower boundary 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 tangent ellipse intersecting the ground.

5. The design method according to claim 4, characterized in that: The second area is: Wherein, S2 is the second area, ∠D is the angle between the upper boundary of the radiation space cone model and the ground, and ΔL2 is the distance of the current axis change relative to the line-to-ground distance.

6. The design method according to claim 5, characterized in that: The irradiation area is calculated by the following formula: in, It is the overlapping part of the first area and the second area.

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