Low-scattering carrier for darkroom background level evaluation test

Abstract

The invention provides a low-scattering carrier for darkroom background level evaluation test, and relates to the technical field of target far-field electromagnetic scattering characteristic test, the low-scattering carrier is a hollow structure formed by seamless connection of an upper surface and a lower surface; the upper surface comprises a plurality of smooth curved surfaces with continuous curvatures, and the lower surface is a smooth plane; the forward direction of the low-scattering carrier is a sharp needle-shaped tip; and the lower surface is provided with a circular truncated cone hole for embedding a two-dimensional rotating top at the top end of the metal bracket and a connecting structure for connecting and fixing the two-dimensional rotating top. The forward direction of the low-scattering carrier provided by the invention is a sharp needle-shaped tip, so that the low-scattering carrier can be ensured to have a low-scattering characteristic in a relatively wide angular domain range in the forward direction, strong RCS scattering of the two-dimensional rotating top can be shielded, the RCS of the metal bracket can be measured more accurately, and a more accurate darkroom background level can be further obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of target far-field electromagnetic scattering characteristic testing, and particularly relates to a low-scattering carrier for darkroom background level evaluation testing. Background Art

[0002] When conducting component RCS (Radar Cross Section) testing in a microwave anechoic chamber, it is necessary to accurately evaluate the anechoic chamber background level. Since the RCS value of the target under test is getting lower and lower, and the RCS of the low-scattering bracket itself is not low enough, a low-scattering carrier with a lower RCS is required to cooperate with the bracket for testing to eliminate the strong RCS scattering of the bracket itself, so as to obtain a more accurate anechoic chamber background level and further more precisely evaluate the RCS of the target under test. Summary of the Invention

[0003] Aiming at one or more problems existing in the prior art, the present invention provides a low-scattering carrier for darkroom background level evaluation testing. The front of the low-scattering carrier provided by the present invention is a pointed needle tip, which can ensure that the front of the low-scattering carrier has low-scattering characteristics within a relatively wide angular range. A two-dimensional rotating top circular hole for embedding the top of the metal bracket is provided on the lower surface of the low-scattering carrier, which can block the strong RCS scattering of the two-dimensional rotating top itself, more accurately measure the RCS of the metal bracket itself, and thus obtain a more accurate anechoic chamber background level.

[0004] A low-scattering carrier for darkroom background level evaluation testing, the low-scattering carrier is a hollow structure formed by seamless connection of an upper surface and a lower surface; the upper surface includes a plurality of smooth surfaces with continuous curvature, and the lower surface is a smooth plane; the front of the low-scattering carrier is a pointed needle tip; a circular hole of a two-dimensional rotating top for embedding the top of the metal bracket and a connection structure for connecting and fixing the two-dimensional rotating top are provided on the lower surface.

[0005] In a possible design, the upper surface at least includes a first smooth surface protruding upward and a second smooth surface recessed downward; the second smooth surface is connected to the lower surface to form a pointed needle tip.

[0006] In a possible design, the roughness of the upper surface and the lower surface is less than 1.6.

[0007] In a possible design, the included angle of the pointed needle tip in the horizontal direction is 5-20°.

[0008] In a possible design, the projection of the rear end in the horizontal direction is an arc angle.

[0009] In a possible design, the arc angle is 30-100°.

[0010] In a possible design, the included angle between the lower surface and the horizontal plane is 0°.

[0011] In a possible design, the lower surface of the two-dimensional rotating top is flush with the lower surface of the low-scattering carrier.

[0012] In a possible design, the length of the low-scattering carrier is 2 - 4 m, the width is 0.8 - 2 m, and the height is 0.3 - 0.5 m.

[0013] In a possible design, the connection structure is a frustum flange interface.

[0014] The present invention has at least the following beneficial effects compared with the prior art:

[0015] The forward of the low-scattering carrier of the present invention is a sharp needle-shaped tip, which can ensure that the forward of the low-scattering carrier has low-scattering characteristics within a relatively wide angular range. A two-dimensional rotating top frustum hole for embedding the top end of the metal bracket is provided on the lower surface of the low-scattering carrier, which can block the strong RCS scattering of the two-dimensional rotating top itself, more accurately measure the RCS of the metal bracket itself, obtain a more accurate darkroom background level, and further more precisely evaluate the RCS of the target under test. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 is an oblique view of the low-scattering carrier provided by the present invention for darkroom background level evaluation test;

[0018] Figure 2 is a schematic structural diagram of the upper surface of the low-scattering carrier provided by the present invention for darkroom background level evaluation test;

[0019] Figure 3 is a top view of the low-scattering carrier provided by the present invention for darkroom background level evaluation test;

[0020] Figure 4 is a side view of the low-scattering carrier provided by the present invention for darkroom background level evaluation test;

[0021] Figure 5 is an embedding diagram of the low-scattering carrier and the two-dimensional rotating top provided by the present invention for darkroom background level evaluation test.

[0022] Reference numerals:

[0023] 1 - low - scattering carrier; 11 - upper surface; 12 - lower surface; 121 - frustum - shaped hole; 2 - metal bracket. Specific implementation manner

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] A low - scattering carrier for evaluating the background level of a darkroom, as Figure 1 shown, the low - scattering carrier 1 is a hollow structure formed by seamlessly connecting the upper surface 11 and the lower surface 12; the upper surface 11 includes a plurality of smooth curved surfaces with continuous curvature, and the lower surface 12 is a smooth plane; the front of the low - scattering carrier 1 is a sharp - needle - shaped tip; the lower surface 12 is provided with a frustum - shaped hole 121 for embedding the top of the two - dimensional rotating top of the metal bracket 2 and a connecting structure for connecting and fixing the two - dimensional rotating top.

[0026] Considering that after the overall radar cross - section design of the aircraft is completed, it is necessary to evaluate the RCS at the component level. When the pitch angle range of the target under test is large, a support method using a metal bracket is required to support the target under test. Since the RCS value of the target under test is getting lower and lower, and the RCS of the low - scattering bracket itself is not low enough, it is necessary to use a low - scattering carrier with a lower RCS to cooperate with the bracket for testing, eliminate the strong RCS scattering of the bracket itself, obtain a more accurate darkroom background level, and then more accurately evaluate the RCS of the target under test.

[0027] Based on this, the front of the low - scattering carrier of the present invention is a sharp - needle - shaped tip, which can ensure that the front of the low - scattering carrier has low - scattering characteristics within a wide angular range. The lower surface of the low - scattering carrier is provided with a frustum - shaped hole for the two - dimensional rotating top to embed the top of the metal bracket, which can block the strong RCS scattering of the two - dimensional rotating top itself, more accurately measure the RCS of the metal bracket itself, obtain a more accurate darkroom background level, and then more accurately evaluate the RCS of the target under test.

[0028] In some preferred embodiments, the upper surface 11 at least includes a first smooth curved surface that bulges upward and a second smooth curved surface that depresses downward; the second smooth curved surface is connected to the lower surface to form a needle-shaped tip. The part of the upper surface other than the second smooth curved surface is connected to the lower surface to form the middle and rear ends of the cavity of the low-scattering carrier hollow structure. Connecting the upper surface with the above structure to the planar lower surface can form a low-scattering carrier with low-scattering characteristics, without the need to set both the upper and lower surfaces as curved surfaces to ensure the low-scattering characteristics of the carrier, which can greatly reduce the cost of the low-scattering carrier.

[0029] It should be noted that the upward and downward here refer to the Figure 4 up and down in, and the bulge and depression are relative to the cavity of the hollow structure.

[0030] In some preferred embodiments, the roughness of the upper surface 11 and the lower surface 12 is less than 1.6. The roughness of the upper surface and the lower surface of the low-scattering carrier in this embodiment is less than 1.6 (profile arithmetic mean deviation), which is more conducive to reducing the scattering generated when electromagnetic waves propagate on the carrier. All the seams on the surface of the low-scattering carrier are very fine and there is no step difference on the curved surface.

[0031] In some preferred embodiments, the angle of the needle-shaped tip in the horizontal direction is 5-20°.

[0032] The magnitudes of the forward angle and the backward angle of the low-scattering carrier determine the low-scattering angular domain of the low-scattering carrier. For special requirements for the size of the RCS angular domain, it is extremely important to select an appropriate tip angle. As Figure 2-3 shown, the forward end of the low-scattering carrier in this embodiment is provided with a needle-shaped tip, and the angle of the tip is controlled within the above range to ensure that the low-scattering carrier has low-scattering performance in a relatively wide angular domain forward. The tip of the low-scattering carrier of the present invention can be composed of a straight line or a curve. When composed of a straight line, the angle between the two straight lines is the tip angle; when the tip is composed of a curve, the angle formed by the tangents along the curve forms the tip angle.

[0033] In some more preferred embodiments, the angle of the needle-shaped tip in the horizontal direction is 7°.

[0034] In some preferred embodiments, the projection of the rear end in the horizontal direction is an arc angle.

[0035] In some preferred embodiments, the arc angle is 30-100°

[0036] In some more preferred embodiments, the arc angle is 70°.

[0037] In some preferred embodiments, the angle between the lower surface 12 and the horizontal plane is 0°. As Figure 4As shown, the angle between the plane where the upper surface and the lower surface of the low-scattering carrier in this embodiment meet and the horizontal plane is 0 degree. Since the lower surface is a plane, the plane where the upper surface and the lower surface meet is the plane where the lower surface is located. The first smooth curved surface near the tip of the upper surface of the low-scattering carrier in this embodiment is concave inward with respect to the hollow structure cavity of the low-scattering carrier, and is connected to the lower surface to form a sharp needle-shaped tip. The second smooth curved surface away from the tip of the upper surface is convex upward with respect to the hollow structure cavity of the low-scattering carrier, and is connected to the lower surface to form the middle and rear ends of the hollow structure cavity of the low-scattering carrier.

[0038] In some preferred embodiments, the lower surface of the two-dimensional turntop is flush with the lower surface 12 of the low-scattering carrier. A frustum-shaped hole is provided on the lower surface of the low-scattering carrier in this embodiment, and a connection structure for connecting and fixing the two-dimensional turntop is provided at the position of the frustum-shaped hole. The connection structure matches the flange structure of the two-dimensional turntop. When performing the RCS test, the two-dimensional turntop needs to be embedded at the frustum-shaped hole of the low-scattering carrier and fixedly connected to the low-scattering carrier through the connection structure. After connection, the lower surface of the low-scattering carrier and the lower surface of the two-dimensional turntop are flush at the joint, without a step difference, and the surface curvature is continuous. Aluminum foil is pasted at the small gap between the two. In this way, not only can the strong RCS scattering of the two-dimensional turntop itself be effectively blocked, but also it can be ensured that there will be no echo reflection of surface discontinuity and strong specular reflection source at the joint, improving the accuracy of the RCS measurement of the metal bracket itself, obtaining a more accurate darkroom background level, and then more accurately evaluating the RCS of the target under test.

[0039] In some preferred embodiments, the length of the low-scattering carrier 1 is 2 - 4 m, the width is 0.8 - 2 m, and the height is 0.3 - 0.5 m. The length of the low-scattering carrier of the present invention refers to Figure 3 the maximum distance in the horizontal direction in Figure 3 and the width refers to Figure 4 the maximum distance in the vertical direction in

[0040] In some preferred embodiments, the connection structure is a frustum flange interface. A frustum-shaped hole is provided on the lower surface of the low-scattering carrier in this embodiment, and a connection structure for connecting and fixing the two-dimensional turntop is provided at the position of the frustum-shaped hole. The connection structure matches the flange structure of the two-dimensional turntop. The connection structure is a frustum flange interface, and the two-dimensional turntop is installed on the frustum flange interface through countersunk head screws; after installation, the lower surface of the two-dimensional turntop is flush with the lower surface of the carrier, and the small gap at the joint between the two can be pasted with aluminum foil, which can be used to test the RCS of the metal bracket itself.

[0041] Due to the relatively continuous surface curvature and no concave cavity and other structures, the low-scattering carrier designed above in the present invention has no strong scattering sources such as specular reflection and multiple reflections on the surface, and has a good surface current guiding effect. AsFigure 5 As shown, in actual tests, a two-dimensional rotary top can be embedded at the position of the frustum-shaped hole on the lower surface. The lower surface of the two-dimensional rotary top is flush with the lower surface of the low-scattering carrier at the joint without a step difference, and the surface curvature is continuous. Aluminum foil is pasted at the small gap between the two to ensure that there will be no echo reflection of surface discontinuity and strong specular reflection sources at the connection, and at the same time, the strong RCS scattering of the two-dimensional rotary top itself can be effectively blocked. Due to the low-scattering characteristics of the low-scattering carrier itself, its RCS is much lower than that of the metal bracket itself, which has no influence on the RCS test of the metal bracket, can more accurately measure the RCS of the metal bracket itself, obtain a more accurate darkroom background level, and then more precisely evaluate the RCS of the target under test. The size and weight of the above-mentioned low-scattering carrier are within the test capabilities of most experimental platforms, which is convenient for operation and can be used in most target test fields to accurately test and evaluate the darkroom background level. The low-scattering carrier provided by the present invention is reliable and applicable, easy to promote, and has good economic benefits.

[0042] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; unless otherwise specified or stated, the term "multiple groups" means two or more groups; the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "connection" 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 those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In the description of this specification, it should be understood that the orientation terms such as "upper" and "lower" described in the embodiments of the present invention are described from the angles shown in the drawings and should not be construed 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 "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; 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 invention.

Claims

1. A low scattering carrier for darkroom background level assessment test, characterized in that: The low-scattering carrier is a hollow structure formed by seamlessly connecting the upper surface and the lower surface; the upper surface includes a plurality of smooth curved surfaces with continuous curvature, and the lower surface is a smooth plane; the front of the low-scattering carrier is a sharp needle-shaped tip; The lower surface is provided with a truncated cone hole for embedding the two-dimensional rotating top at the top of the metal bracket and a connecting structure for connecting and fixing the two-dimensional rotating top.

2. The low scattering carrier according to claim 1, characterized in that: The upper surface at least comprises a first smooth curved surface convex upward and a second smooth curved surface concave downward; the second smooth curved surface is connected to the lower surface to form a sharp needle-shaped tip.

3. The low scattering carrier according to claim 1, characterized in that: The roughness of the upper surface and the lower surface is less than 1.

6.

4. The low scattering carrier according to claim 1, characterized in that: The angle of the needle-shaped tip in the horizontal direction is 5 to 20 degrees.

5. The low scattering carrier according to claim 4, characterized in that: The projection of the rear end in the horizontal direction is an arc angle.

6. The low scattering carrier according to claim 5, characterized in that: The arc angle is 30 to 100 degrees.

7. The low scattering carrier according to claim 1, characterized in that: The angle between the lower surface and the horizontal plane is 0°.

8. The low scattering carrier according to claim 1, characterized in that: The lower surface of the two-dimensional rotating top is flush with the lower surface of the low-scattering carrier.

9. The low scattering carrier according to claim 1, characterized in that: The low scattering carrier has a length of 2 to 4 m, a width of 0.8 to 2 m, and a height of 0.3 to 0.5 m.

10. The low scattering carrier according to claim 1, characterized in that: The connection structure is a truncated cone flange interface.

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