CN102570047A - Edge progressive impedance loading film and edge progressive impedance loading structure - Google Patents

Abstract

An edge gradual impedance loading structure and a preparation method thereof belong to the technical field of electronic materials. The resistance film is provided with progressive periodic square aluminum foil patches and progressive periodic hole units which are complementary with the patches, the side lengths of the progressive square aluminum foil units and the hole units are respectively 8mm, 5mm, 2mm and 10mm, and the unit interval, namely the period is L. The invention can obtain good edge scattering inhibition when the frequency, the polarization mode and the azimuth angle change.

Description

Edge progressive impedance loading film and edge progressive impedance loading structure

technical field

The invention belongs to the technical field of electronic materials, and in particular relates to an electromagnetic scattering suppression mechanism of edge electromagnetic defects and a preparation method thereof.

Background technique

Since World War II, stealth technology related to target electromagnetic backscatter control has become the research focus of countries all over the world. With the rapid development of modern military technology, the detection, tracking, and attack capabilities of the defense systems of major countries in the world are becoming stronger and stronger, making the threats to the penetration weapon systems of various countries more and more serious. technology. The radar system is by far the most effective target detection tool in the military field. It judges the nature of the target based on the scattering of radar waves by the target. The radar cross section (RCS) of a target is an important factor in the characteristic signal of a radar target and a basic indicator to measure the detectability of a target. The core of stealth technology is to reduce the RCS of the target as much as possible, thereby reducing the probability of being discovered by the enemy radar detection system. Improve its penetration ability. Therefore, stealth technology depends to a large extent on the research on the target RCS.

For conventional aircraft, specular scattering sources, corner bodies, and cavities become the main scattering sources. However, for stealth aircraft, the above-mentioned main scattering sources have been effectively controlled, and the electromagnetic scattering of secondary scattering sources such as steps, gaps, and edges has become the main scattering source. The research on its reduction measures has become a very urgent task. At present, the relatively mature edge scattering suppression scheme adopts edge sawtooth, which is a method to effectively reduce the RCS through shaping design. However, when the azimuth angle changes slightly, the edge scattering suppression effect drops obviously, and when the azimuth angle reaches Occasionally there will be large oscillations and far exceed the RCS of an unaliased target. Therefore, it is necessary to re-study the problem of edge scattering control, and it is urgent to obtain a method to suppress edge scattering. When the frequency, azimuth angle and polarization mode are changed, a good edge suppression effect can still be obtained.

Contents of the invention

The technical problem to be solved by the present invention is to provide an edge progressive impedance loading and its preparation method, so that the edge scattering of the loaded target body wave structure can be effectively suppressed in the changing frequency, polarization mode and azimuth angle.

The technical solution adopted by the present invention to solve the technical problem is that the edge progressive impedance loading film is characterized in that aluminum foil patches and hole units are arranged in rows and columns on the impedance film, and each row includes progressive periodic aluminum foil patches and associated with them. Complementary progressive periodic hole units, the arrangement of each row is the same; the shape and size of the aluminum foil patches in each column are the same, the shape and size of the hole units in each column are the same, and the columns are aligned.

Further, both the aluminum foil patch and the hole unit are square. The distance between the center points of adjacent aluminum foil patches is equal, and the distance between the center points of adjacent hole units is equal. From the middle position to both sides, the size of the aluminum foil patch and the hole gradually increases.

Furthermore, from the middle position to both sides, the side lengths of the first-level aluminum foil patch and the first-level hole unit are both 2mm, and the side lengths of the second-level aluminum foil patch and the second-level hole unit are both 5mm. The side lengths of the third-level aluminum foil patch and the third-level hole unit are both 8mm, the distance between the center points of adjacent aluminum foil patches is 10mm, and the distance between the center points of adjacent hole units is 10mm, and the first-level aluminum foil patch The distance from the first-level hole unit is 10mm.

Or, the aluminum foil patch and the hole unit are both circular, from the middle position to both sides, the radius of the first-level aluminum foil patch and the first-level hole unit is 1mm, the second-level aluminum foil patch and the second-level The radius of the hole unit is 2.5mm, the radius of the third-level aluminum foil patch and the third-level hole unit are both 4mm, the distance between the center points of adjacent aluminum foil patches is 10mm, and the distance between the center points of adjacent hole units is 10mm, the distance between the first-level aluminum foil patch and the first-level hole unit is 10mm.

The aforementioned first level, second level, and third level are graded from small to large.

The present invention also provides an edge progressive impedance loading structure with the aforementioned edge progressive impedance loading film, which is characterized in that the edge progressive impedance loading film is close to the straight edge of the target, and the direction is: the aluminum foil patch is close to the straight edge of the target part, the hole unit is away from the straight edge part of the target body.

The present invention has the following outstanding advantages:

Compared with the existing impedance film, it is easier to realize, and has a wide range of square resistance; the process is simple, the operability is strong, and the cost is low; when the frequency, polarization mode and azimuth angle change, it can achieve good edge scattering suppression. By properly adjusting the graphic unit size of the aluminum foil patch and the hole, a good edge scattering suppression effect can be obtained. The graphic units of aluminum foil patches and holes can be replaced by other complementary periodic structural units. The structure can be used for suppressing electromagnetic scattering of through-hole gaps without a ground plate.

Description of drawings

Figure 1 is a schematic diagram of the structure of the target body.

Fig. 2 is a structural schematic diagram of the present invention.

FIG. 3 is a schematic structural diagram of a progressive impedance unit along X-X in FIG. 2 . Among them, a, b, and c are the side lengths of the gradient patches and holes, and the period is L.

Fig. 4 is a schematic structural diagram of a progressive impedance unit of a circular periodic complementary unit.

In the figure, 1 is an aluminum foil patch, 2 is a hole unit, and 3 is an impedance film.

Detailed ways

The invention provides an edge progressive impedance loading structure, which is formed by introducing progressive complementary periodic structures on the impedance film. The impedance of the resistive film is 300Ω/◇, and the periodic structure adopts square patches and square holes with complementary structures.

Complementarity referred to in the present invention refers to the same shape and size, and symmetrical positions.

The periodic structure referred to in the present invention means that the center points of any two adjacent units (aluminum foil patches or holes) have the same distance, and both have a period length, which is called L. In particular, at the middle position, the distance between the smallest aluminum foil patch and the center point of the smallest hole unit is also L.

The object processed by the present invention is to cut an aluminum plate with a thickness of 1mm and an area of 400mm×400mm along the diagonal, and then remove the corners to obtain the edge to be processed. Its basic structure is shown in Figure 1.

The edge progressive impedance loading structure of the present invention can be prepared by the following method:

Step 1: Prepare an impedance film with a width w and a length corresponding to the target object, and its impedance is 300Ω/◇. Then, the resistive film is processed by mechanical means, and the side lengths of three periods of square holes counting from one side are a, b and c respectively, and their periods are all 10 mm. Step 2: Prepare aluminum foil with a width of 30mm and a thickness of less than 0.1mm. Then the aluminum foil is engraved by mechanical means, the processing cycle of the three rows is 10mm, and the side lengths of the square patches are a, b and c respectively. The engraved patch and the aluminum foil cannot be separated immediately, so it is ready for the next step of alignment. Step 3: Paste the processed aluminum foil on the other side of the processed hole of the impedance film, which is exactly 30mm wide. The foil patch is then partially glued and excess foil removed. The final progressive impedance film is shown in Figure 2, which includes the coordinate system of electromagnetic wave incident. A schematic diagram of the structure of a progressive impedance unit obtained along X-X is shown in Fig. 3 .

The largest aluminum foil patch of the unit of the present invention is close to the edge of the object, that is, the side with the smaller equivalent impedance is in contact with the loading edge.

The width of the resistance strip of the present invention can be properly extended in the direction of the patch, which is convenient for close connection with the edge of the target body, and the thin resistance film is directly pasted on the metal target body without changing the metal property.

The characterization of the edge scattering suppression of the present invention is characterized by the reduction effect of the radar cross section (RCS) of a single station in the present invention, which is obtained by comparing it with the single station RCS under the condition that the same target body is not loaded.

Example 1:

An edge progressive impedance loading structure is formed by pasting progressive periodic square aluminum foil patches on the impedance film and engraving its complementary progressive periodic hole units. The side lengths of the progressive square aluminum foil unit and the hole unit are a=8mm, b=5mm, c=2mm respectively, and the unit spacing, that is, the period, is L=10mm.

变化从-45°～45°下进行俯仰角θ扫描，俯仰角θ变化为-90°～90°，其中方位角和俯仰角的定义如图2所示。在10GHz平面波入射，方位角为0°时：水平极化情况下导波前缘在俯仰角θ为30°左右时取得最大RCS减缩为28dB，在后缘俯仰角θ为-30°左右时取得最大RCS减缩为38dB，在整个俯仰角变化范围-90°～90°内都能取得RCS减缩，特别在大角度范围-90°～-30°范围取得很好的RCS减缩效果，后缘减缩效果明显优于前缘；垂直极化情况下导波前缘在俯仰角θ为30°左右时取得最大RCS减缩为35dB，在后缘俯仰角θ为-30°左右时取得最大RCS减缩为30dB。在整个俯仰角变化范围-90°～90°内都能取得RCS减缩，特别在大角度范围30°～90°范围取得很好的RCS减缩效果，前缘减缩效果明显优于后缘。The edge progressive impedance loading structure of this embodiment is mainly aimed at the case of large-angle incidence, and the case of specular scattering is not considered in this design. For both vertical and horizontal polarizations, in azimuth

The pitch angle θ is scanned from -45° to 45°, and the pitch angle θ changes from -90° to 90°. The definitions of the azimuth and pitch angles are shown in Figure 2. When the 10GHz plane wave is incident and the azimuth angle is 0°: in the case of horizontal polarization, the leading edge of the guided wave achieves the maximum RCS reduction of 28dB when the pitch angle θ is about 30°, and the maximum RCS reduction is obtained when the pitch angle θ of the trailing edge is about -30° The maximum RCS reduction is 38dB, and RCS reduction can be achieved in the entire pitch angle range of -90°~90°, especially in the large angle range of -90°~-30°, and the trailing edge reduction effect is very good It is obviously better than the leading edge; in the case of vertical polarization, the leading edge of the guided wave achieves a maximum RCS reduction of 35dB when the pitch angle θ is about 30°, and a maximum RCS reduction of 30dB when the pitch angle θ of the trailing edge is about -30°. RCS reduction can be obtained in the entire pitch angle range of -90° to 90°, especially in the large angle range of 30° to 90°, and the leading edge reduction effect is obviously better than that of the trailing edge.

When the 10GHz plane wave is incident and the azimuth angle is 10°: in the case of horizontal polarization, the leading edge of the guided wave achieves a maximum RCS reduction of 24dB when the pitch angle θ is about 50°, and the RCS reduction effect of the trailing edge is not obvious, but in the whole scanning pitch The RCS reduction effect has been achieved in the angular range, especially in the large angle range of -90°～-45°, and the trailing edge reduction effect is obviously better than that of the leading edge; in the case of vertical polarization, the leading edge and the The RCS reduction effect of the trailing edge is basically the same, the RCS reduction effect of the leading edge is slightly better than that of the trailing edge, and the RCS reduction effect of about 10dB is obtained on average in the range of pitch angle from ±15° to ±90°.

变化从-45°～45°下的其他情况，随着方位角偏离0°，减缩效果逐渐变差，两种极化变化趋势基本一致。垂直极化变化情况小于水平极化。在整个角域都都有一定的RCS减缩效果。不会出现边缘锯齿化结构在方位角偏离0°时出现反减缩情况，而且超过特定值时出现多个旁瓣情况。When the 10GHz plane wave is incident and the azimuth angle is 15°: in the case of horizontal polarization, the leading edge of the guided wave achieves the maximum RCS reduction of 20dB when the pitch angle θ is about 40°, and the RCS reduction effect of the trailing edge is not obvious, but in the whole scanning pitch The RCS reduction effect has been achieved in the angular range, especially in the large angle range of -90°～-40°, and the trailing edge reduction effect is obviously better than that of the leading edge; in the case of vertical polarization, the leading edge and the The RCS reduction effect of the trailing edge is basically the same, and the RCS reduction effect of the trailing edge is slightly better than that of the trailing edge. An average RCS reduction effect of about 10dB is obtained in the range of pitch angles from ±20° to ±90°. in azimuth

In other cases where the variation ranges from -45° to 45°, as the azimuth angle deviates from 0°, the reduction effect gradually becomes worse, and the variation trends of the two polarizations are basically the same. The variation of vertical polarization is smaller than that of horizontal polarization. There is a certain RCS reduction effect in the entire angular field. There will be no anti-shrinkage of the edge sawtooth structure when the azimuth angle deviates from 0°, and multiple side lobes will appear when the azimuth angle exceeds a certain value.

Example 2:

An edge progressive impedance loading structure is formed by pasting progressive periodic circular aluminum foil patches on the impedance film and engraving its complementary progressive periodic hole units. The radii of the progressive circular aluminum foil unit and the hole unit are r1=4mm, r2=2.5mm, r3=1mm respectively, and the unit spacing, that is, the cycle, is L=10mm.

变化从-45°～45°下进行俯仰角θ扫描，俯仰角θ变化为-90°～90°，其中方位角和俯仰角的定义如图2所示。在10GHz平面波入射，方位角为0°时：水平极化情况下导波前缘在俯仰角θ为35°左右时取得最大RCS减缩为20dB，在后缘俯仰角θ为-28°左右时取得RCS减缩峰20dB，在整个俯仰角变化范围-90°～90°内都能取得RCS减缩，特别在大角度范围-90°～-25°范围取得很好的RCS减缩效果，后缘减缩效果明显优于前缘；垂直极化情况下导波前缘在俯仰角θ为50°左右时取得最大RCS减缩为25dB，在后缘俯仰角θ为-58°左右时取得RCS减缩峰20dB。在整个俯仰角变化范围-90°～90°内都能取得RCS减缩，特别在大角度范围25°～90°范围取得很好的RCS减缩效果，前缘减缩效果明显优于后缘。在方位角

变化从-45°～45°下的其他角域，随着方位角偏离0°，减缩效果逐渐变差，两种极化变化趋势基本一致。垂直极化变化情况小于水平极化。在整个角域都都有一定的RCS减缩效果。不会出现边缘锯齿化结构在方位角偏离0°时出现反减缩情况，而且超过特定值时出现多个旁瓣情况。对应情况下的RCS减缩效果不如实施例1。主要原因是圆形单元面积小于方形单元，所构造的渐进阻抗特性不如方形单元。This embodiment is mainly aimed at the case of large-angle incidence, and the case of specular scattering is not considered in this design. For both vertical and horizontal polarizations, in azimuth

The pitch angle θ is scanned from -45° to 45°, and the pitch angle θ changes from -90° to 90°. The definitions of the azimuth and pitch angles are shown in Figure 2. When the 10GHz plane wave is incident and the azimuth angle is 0°: in the case of horizontal polarization, the leading edge of the guided wave achieves the maximum RCS reduction of 20dB when the pitch angle θ is about 35°, and the maximum RCS reduction is obtained when the pitch angle θ of the trailing edge is about -28° The RCS reduction peak is 20dB, and RCS reduction can be obtained in the entire pitch angle range of -90°～90°, especially in the large angle range of -90°～-25°, and the trailing edge reduction effect is obvious It is better than the leading edge; in the case of vertical polarization, the leading edge of the guided wave achieves a maximum RCS reduction of 25dB when the pitch angle θ is about 50°, and a peak RCS reduction of 20dB when the pitch angle θ of the trailing edge is about -58°. RCS reduction can be achieved in the entire pitch angle range of -90° to 90°, especially in the large angle range of 25° to 90°, and the leading edge reduction effect is obviously better than that of the trailing edge. in azimuth

In other angle domains that vary from -45° to 45°, as the azimuth angle deviates from 0°, the reduction effect gradually becomes worse, and the two kinds of polarization change trends are basically the same. The variation of vertical polarization is smaller than that of horizontal polarization. There is a certain RCS reduction effect in the entire angular field. There will be no anti-shrinkage of the edge sawtooth structure when the azimuth angle deviates from 0°, and multiple side lobes will appear when the azimuth angle exceeds a certain value. The RCS reduction effect in the corresponding case is not as good as that of Example 1. The main reason is that the area of the circular unit is smaller than that of the square unit, and the progressive impedance characteristic of the structure is not as good as that of the square unit.

Example 3:

An edge progressive impedance loading structure is formed by pasting progressive periodic square aluminum foil patches on the impedance film and engraving its complementary progressive periodic hole units. The side lengths of the progressive square aluminum foil unit and the hole unit are a=8.5mm, b=5.5mm, c=1.5mm respectively, and the unit spacing, that is, the cycle, is L=10mm.

变化从-45°～45°下进行俯仰角θ扫描，俯仰角θ变化为-90°～90°，其中方位角和俯仰角的定义如图2所示。在10GHz平面波入射，方位角为0°时：水平极化情况下导波前缘在俯仰角θ为35°左右时取得最大RCS减缩为22dB，在后缘俯仰角θ为-35°左右时取得RCS减缩峰28dB，在整个俯仰角变化范围-90°～90°内都能取得RCS减缩，特别在大角度范围-90°～-30°范围取得很好的RCS减缩效果，后缘减缩效果明显优于前缘；垂直极化情况下导波前缘在俯仰角θ为50°左右时取得最大RCS减缩为30dB，在后缘俯仰角θ为-50°左右时取得RCS减缩峰22dB。在整个俯仰角变化范围-90°～90°内都能取得RCS减缩，特别在大角度范围30°～90°范围取得很好的RCS减缩效果，前缘减缩效果明显优于后缘。在方位角变化从-45°～45°下的其他角域，随着方位角偏离0°，减缩效果逐渐变差，两种极化变化趋势基本一致。垂直极化变化情况小于水平极化。在整个角域都都有一定的RCS减缩效果。不会出现边缘锯齿化结构在方位角偏离0°时出现反减缩情况，而且超过特定值时出现多个旁瓣情况。对应情况下的RCS减缩效果不如实施例1。主要原因是第一个方形单元面积减小，而后面两个方向单元面积增大，造成渐进梯度发生改变造成的。The edge progressive impedance loading structure designed by the above method is mainly aimed at the case of large-angle incidence, and the case of specular scattering is not considered in this design. For both vertical and horizontal polarizations, in azimuth

The pitch angle θ is scanned from -45° to 45°, and the pitch angle θ changes from -90° to 90°. The definitions of the azimuth and pitch angles are shown in Figure 2. When the 10GHz plane wave is incident and the azimuth angle is 0°: in the case of horizontal polarization, the leading edge of the guided wave achieves the maximum RCS reduction of 22dB when the pitch angle θ is about 35°, and the maximum RCS reduction is achieved when the pitch angle θ of the trailing edge is about -35° The RCS reduction peak is 28dB, and the RCS reduction can be obtained in the entire pitch angle range of -90°～90°, especially in the large angle range of -90°～-30°, and the trailing edge reduction effect is obvious Better than the leading edge; in the case of vertical polarization, the leading edge of the waveguide achieves a maximum RCS reduction of 30dB when the pitch angle θ is about 50°, and a peak RCS reduction of 22dB when the pitch angle θ of the trailing edge is about -50°. RCS reduction can be obtained in the entire pitch angle range of -90° to 90°, especially in the large angle range of 30° to 90°, and the leading edge reduction effect is obviously better than that of the trailing edge. in azimuth In other angle domains that vary from -45° to 45°, as the azimuth angle deviates from 0°, the reduction effect gradually becomes worse, and the two kinds of polarization change trends are basically the same. The variation of vertical polarization is smaller than that of horizontal polarization. There is a certain RCS reduction effect in the entire angular field. There will be no anti-shrinkage of the edge sawtooth structure when the azimuth angle deviates from 0°, and multiple side lobes will appear when the azimuth angle exceeds a certain value. The RCS reduction effect in the corresponding case is not as good as that of Embodiment 1. The main reason is that the area of the first square unit decreases, while the area of the units in the following two directions increases, resulting in a gradual change in the gradient.

The preparation methods of the edge progressive impedance loading structures described in the above three specific embodiments are the same as those described in the summary of the invention, and will not be repeated here.

Claims (6)

1. Edge progressive impedance loading film is characterized in that aluminum foil patches and hole units are arranged in rows and columns on the impedance film, and each row includes progressive periodic aluminum foil patches and progressive periodic hole units complementary to it. The cloth is the same; the shape and size of the aluminum foil patches in each column are the same, the shape and size of the hole units in each column are the same, and the columns are aligned. 2. The edge progressive resistance loading structure according to claim 1, characterized in that, both the aluminum foil patches and the hole units are square. 3. The edge progressive impedance loading film as claimed in claim 1, characterized in that, the distances between the center points of adjacent aluminum foil patches are equal, the distances between the center points of adjacent hole units are equal, from the middle position to both sides, the aluminum foil patch with a gradual increase in hole size. 4. The edge progressive impedance loading film as claimed in claim 2, characterized in that, from the middle position to both sides, the side lengths of the first-level aluminum foil patch and the first-level hole unit are both 2mm, and the second-level aluminum foil patch The side lengths of the sheet and the second-level hole unit are both 5mm, the side lengths of the third-level aluminum foil patch and the third-level hole unit are both 8mm, the distance between the center points of adjacent aluminum foil patches is 10mm, and the adjacent holes The center point distance of the unit is 10mm, and the distance between the first-level aluminum foil patch and the first-level hole unit is 10mm. 5. The edge progressive resistance loading film as claimed in claim 1, characterized in that, the aluminum foil patch and the hole unit are all circular, from the middle position to both sides, the first-level aluminum foil patch and the first-level hole The radius of the unit is 1mm, the radius of the second-level aluminum foil patch and the second-level hole unit is 2.5mm, the radius of the third-level aluminum foil patch and the third-level hole unit is 4mm, and the adjacent aluminum foil patch The distance between the center points of the aluminum foil patch and the first-level hole unit is 10mm, the distance between the center points of adjacent hole units is 10mm, and the distance between the first-level aluminum foil patch and the first-level hole unit is 10mm. 6. The edge progressive impedance loading structure with the edge progressive impedance loading film according to claim 1, characterized in that, the edge progressive impedance loading film is close to the straight edge of the target body, and the direction is: the aluminum foil patch is close to the straight edge of the target body part, the hole unit is away from the straight edge part of the target body.

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