Low-RCS broadband array antenna based on shaping treatment and wave-absorbing material and design method of low-RCS broadband array antenna

Abstract

The invention discloses a low RCS broadband array antenna based on modification processing and a wave absorbing material and a design method of the low RCS broadband array antenna. The design method comprises the following steps: firstly, designing an ultra-wideband Vivaldi antenna working in an X wave band; then analyzing the radiation and scattering surface current distribution of the antenna in the X wave band, and carrying out shaping processing on the antenna according to a simulation result; performing array design on the designed antenna to form an array antenna; and finally, analyzing the surface current in the radiation and scattering states of the array antenna, covering a higher scattering current area with a wave absorbing material, and reserving a high radiation current area of an antenna slot line area so as to reduce the RCS and reserve the radiation performance of the antenna. The low RCS broadband array antenna is designed by adopting the design method. According to the invention, the design requirements of high gain, high directivity and low RCS of the broadband array antenna are met, the effects of in-band RCS reduction, radiation performance maintenance and multi-angle reduction are considered, and the application of the antenna is expanded.

Description

Technical Field

[0001] This invention relates to the field of array antenna technology, and in particular to a design method for a low RCS broadband array antenna based on shape modification and absorbing materials. Background Technology

[0002] Antennas are widely used in radio systems such as communications, broadcasting, television, radar, and navigation, serving to propagate radio waves and are essential devices for effectively radiating and receiving radio waves. Array antennas are a special type of antenna consisting of at least two antenna elements arranged regularly or randomly and achieving predetermined radiation characteristics through appropriate excitation. Ultra-wideband array antennas play a crucial role in both military and civilian fields due to their unique application characteristics.

[0003] Currently, ultra-wideband array antennas face the following main challenges in the design of low radar cross section (RCS):

[0004] (1) Difficulty in reducing in-band RCS. While pursuing ultra-wideband RCS reduction, it is crucial to maintain broadband impedance matching for antenna radiation performance. For example, although the SSPP transmission array achieves 88.8% relative bandwidth RCS reduction, its 3 dB gain bandwidth only covers 9.7-10.7 GHz, approximately 10% of the bandwidth, indicating a technical bottleneck in the coordinated optimization of broadband radiation and scattering performance. Furthermore, when the Vivaldi antenna achieves RCS reduction through surface current reconstruction, performance differences may occur due to polarization sensitivity, such as inconsistent reduction effects under t-polarization and p-polarization.

[0005] (2) The RCS reduction effect is highly sensitive to the incident angle. RCS reduction methods such as checkerboard structure and SSPP phase modulation are dependent on the polarization and angle of the incident wave. For example, the checkerboard structure based on AMC needs to maintain a phase difference of 180°±37° within 8-20 GHz to achieve wide-angle domain scattering cancellation, but its performance may degrade under oblique incidence in practical applications. The RCS reduction effect of Vivaldi antennas varies significantly under different polarizations, and multi-polarization compatibility needs to be achieved through structural optimization.

[0006] (3) Lack of an integrated radiation and scattering design concept. Existing technologies often sacrifice some radiation performance to achieve RCS reduction. For example, applying a frequency-selective surface (FSS) may cause a decrease in radiation efficiency, and when using mirror array technology for magnetoelectric dipole arrays, it is necessary to ensure that the radiation pattern is not affected by the scattering destructive mechanism. Although some designs reported in the literature have achieved ultra-wideband RCS reduction, their maximum gain and bandwidth are still limited by the radiation-scattering coupling effect. Summary of the Invention

[0007] The purpose of this invention is to provide a low-RCS broadband array antenna with high gain, high directivity, low RCS, and high radiation performance based on shape modification and absorbing materials, and its design method.

[0008] The technical solution to achieve the purpose of this invention is: a low RCS broadband array antenna design method based on shape modification and absorbing materials, comprising the following steps:

[0009] Step 1: Design an ultra-wideband Vivaldi antenna operating in the X-band;

[0010] Step 2: Analyze the radiation and scattering surface current distribution of the antenna in the X-band, and modify the antenna shape based on the simulation results;

[0011] Step 3: Design the antenna into an array to form an array antenna;

[0012] Step 4: Analyze the surface current of the radiation and scattering state of the array antenna, cover the area where the scattering current exceeds the threshold with absorbing material, and retain the area in the antenna slot line region where the radiation current is higher than the set value, so as to reduce RCS and retain the antenna radiation performance.

[0013] Furthermore, the design described in step 1 operates on an X-band ultra-wideband Vivaldi antenna, as detailed below:

[0014] S11. Design an ultra-wideband Vivaldi antenna that operates in the X-band. The antenna adopts a coplanar stripline plus microstripline feeding method and includes a top metal layer, a bottom metal layer and a dielectric substrate between the two.

[0015] S12. The top metal layer is the main radiating element of the antenna, which includes a radiating element with a double exponential slot line design, a coplanar strip line for matching, and a ground plane; the bottom metal layer is a microstrip line with a characteristic impedance of 50Ω.

[0016] S13. The antenna is fed through a microstrip line in the bottom metal layer and impedance matched with the radiating element in the X-band via a coplanar strip line.

[0017] S14. In order to optimize the matching effect, the coplanar strip line on the microstrip line feed side was shortened to isolate the ground. That is, the lengths of the coplanar strip lines on both sides are not the same, and the end corresponding to the microstrip line feed is not connected to the ground.

[0018] Furthermore, in step 2, the antenna's radiation and scattering surface current distribution in the X-band is analyzed, and the antenna is reshaped based on the simulation results, as follows:

[0019] S21. Analyze the radiation and scattering surface current distribution of the antenna in the X-band. The high current density region of the antenna in the radiation state is the entire exponential slot line region. The highest density is in the region where the slot line transitions to the vertical region and the coplanar band feed structure, while the current density of the metal layers on both sides is lower. The high current density region of the antenna in the scattering state is also the exponential slot line region and the feed region, but there are also some regions with higher current density in the metal layers on both sides.

[0020] S22. For the exponential groove area, the RCS is reduced by removing the dielectric substrate near the exponential groove that is not covered by a metal layer; for the metal layer areas on both sides, the metal layer is directly reshaped and comb-shaped metal layer is hollowed out on both sides to reduce the scattering current on both sides.

[0021] S23. In order to maintain the antenna's radiation performance during the reshaping process, the antenna's feed section is further optimized. The ground plane of the top metal layer is modified into an isosceles trapezoidal shape, and the microstrip line of the bottom metal layer is modified into an oblique trapezoidal shape, resulting in the final low RCS Vivaldi antenna.

[0022] Furthermore, step 3 involves designing the designed antenna into an array to form an array antenna, as detailed below:

[0023] S31. The simulation data of a single antenna is directly synthesized using simulation software to obtain an approximate array effect. Based on this, the arrangement of the array antenna is obtained, and the optimal element spacing design for a single antenna is 21 mm.

[0024] S32. Since the width of a single antenna is 60 mm, the minimum spacing between antennas placed horizontally along the x-axis is 30 mm. Therefore, the array element antennas are arranged at a 45° angle and the distance between the antennas is controlled at 21 mm, resulting in a horizontal 1×4 one-dimensional linear array.

[0025] S33. Since the array antenna requires a feed network to evenly distribute the feed signal to achieve the array effect, a 1-to-4 Wilkinson power divider is designed for the array elements. By combining the power dividers, the final array antenna is obtained.

[0026] Furthermore, step 4 involves analyzing the surface current of the array antenna's radiation and scattering states, covering areas where the scattering current exceeds a threshold with absorbing material, and preserving areas in the antenna slot region where the radiated current is higher than a set value, in order to reduce the RCS and preserve the antenna's radiation performance, as detailed below:

[0027] S41. Analyze the surface current of the array antenna in the radiation and scattering states. The surface current of the array antenna in the radiation and scattering states is concentrated in the exponential slot line region. The most concentrated areas are the regions where the slot line transitions to the vertical region and the coplanar stripline feed structure. The current density of the metal layers on both sides is relatively low, and there is also a high current density region in the power divider region. The high current density region of the antenna in the scattering state is also in the exponential slot line region and the feed region. There are also some areas with relatively high current density in the metal layers on both sides, and there is also a high scattering current region in the metal part of the power divider region.

[0028] S42. Based on the analysis results, cover the shaping areas on both sides of the antenna and the power divider area at the bottom with absorbing material, and retain the high radiation current area of ​​the antenna slot line area to reduce RCS and retain the antenna radiation performance.

[0029] S43. For the array element part of the array antenna, the scattering is reduced by covering the high scattering current and low radiation current areas at the edge with absorbing material; while for the power divider area, the high scattering current area is directly covered in front of it; the absorbing material is 1.5 mm thick.

[0030] A low RCS broadband array antenna based on shape modification and absorbing materials is designed using the aforementioned design method.

[0031] Compared with the prior art, the significant advantages of this invention are:

[0032] (1) The design bandwidth is 8 GHz to 12 GHz, covering the X band, and the gain within the working frequency band is improved through array design. The maximum gain within the working frequency band is 14.5 dBi, which expands the application of the antenna;

[0033] (2) The Vivaldi antenna was modified to have a low RCS, which resulted in an average RCS reduction of 4 dB under the condition of vertical incidence at the end surface. After arraying, an average RCS reduction of 5.8 dB was achieved by loading absorbing material. The RCS of the array antenna in the frequency band from 7 GHz to 13 GHz was controlled to within an average of -24.6 dBsm and a maximum of -19 dBsm. At the same time, the reduction effect can be maintained at multiple incident angles, achieving in-band reduction while maintaining the antenna radiation characteristics.

[0034] (3) It meets the requirements of broadband array antenna design such as high gain, high directivity and low RCS. Compared with the traditional low scattering design of ultra-wideband array antenna, it also takes into account the in-band RCS reduction, radiation performance maintenance and multi-angle reduction effect. Attached Figure Description

[0035] Figure 1This is a flowchart of the low RCS broadband array antenna design method based on shape modification and absorbing materials according to the present invention.

[0036] Figure 2 This is a schematic diagram of the structure of the ultra-wideband Vivaldi antenna unit designed in an embodiment of the present invention.

[0037] Figure 3 This is a diagram showing the radiation and scattering surface current distribution of the ultra-wideband Vivaldi antenna element designed in this embodiment of the invention at different frequencies.

[0038] Figure 4 This is a schematic diagram of the structure of the improved ultra-wideband Vivaldi antenna element designed in this embodiment of the invention.

[0039] Figure 5 This is a schematic diagram of the antenna element array designed in an embodiment of the present invention.

[0040] Figure 6 This is a schematic diagram of the structure of the 1-to-4 Wilkinson power divider for the array antenna designed in this embodiment of the invention.

[0041] Figure 7 This is a schematic diagram of the complete structure of the array antenna designed in an embodiment of the present invention.

[0042] Figure 8 The diagram shows the radiation and scattering surface current distribution of the complete array antenna structure designed in this embodiment of the invention at different frequencies.

[0043] Figure 9 This is a schematic diagram of the structure of the array antenna designed in this embodiment of the invention after being combined with the absorbing material.

[0044] Figure 10 This is a graph showing the electromagnetic parameters of the absorbing material used in the array antenna designed in this embodiment of the invention.

[0045] Figure 11 This is a single-station RCS curve of the array antenna designed in this embodiment of the invention combined with absorbing materials of different thicknesses. Detailed Implementation

[0046] Combination Figure 1 This invention discloses a low RCS broadband array antenna design method based on shape modification and absorbing materials, comprising the following steps:

[0047] Step 1: Design an ultra-wideband Vivaldi antenna operating in the X-band;

[0048] Step 2: Analyze the radiation and scattering surface current distribution of the antenna in the X-band, and modify the antenna shape based on the simulation results;

[0049] Step 3: Design the antenna into an array to form an array antenna;

[0050] Step 4: Analyze the surface current of the radiation and scattering state of the array antenna, cover the area where the scattering current exceeds the threshold with absorbing material, and retain the area in the antenna slot line region where the radiation current is higher than the set value, so as to reduce RCS and retain the antenna radiation performance.

[0051] As a specific example, the design of the ultra-wideband Vivaldi antenna operating in the X-band described in step 1 is as follows:

[0052] Design an ultra-wideband Vivaldi antenna capable of operating in the X-band. The antenna employs a coplanar stripline and microstrip line feeding method, comprising two metal layers and a dielectric substrate in the middle. The top metal layer is the main radiating element of the antenna, containing a radiating element with a double-exponential slot design, a coplanar stripline for matching, and a ground plane. The back layer is a microstrip line. The antenna is fed through a 50Ω microstrip line on the back, and impedance matching is performed between the antenna and the coplanar stripline in the X-band. To achieve better matching, the coplanar stripline on the microstrip line feeding side is shortened to isolate it from the ground plane; that is, the lengths of the coplanar striplines on both sides are unequal, and one end is not directly connected to ground.

[0053] As a specific example, step 2 involves analyzing the radiation and scattering surface current distribution of the antenna in the X-band, and then modifying the antenna shape based on the simulation results, as follows:

[0054] Step 2.1: Analysis of the radiation and scattering surface current distribution of the antenna in the X-band shows that the high current density region of the antenna in the radiation state is the entire exponential slot line region, especially the region near the transition of the slot line to the vertical region and the coplanar band feed structure, while the current density of the metal layers on both sides is lower; the main high current density regions of the antenna in the scattering state are also the exponential slot line region and the feed region, but there are also some regions with higher current density in the metal layers on both sides.

[0055] Step 2.2: For the exponential groove area, the RCS is reduced by removing the dielectric substrate near the exponential groove that is not covered by a metal layer; for the metal layer areas on both sides, the metal layer is directly reshaped and comb-shaped metal layer is hollowed out on both sides to reduce the scattering current on both sides.

[0056] Step 2.3: In order to avoid a significant impact on the antenna's radiation performance during the reshaping process, the antenna's feed section is further optimized. The ground metal is modified into an isosceles trapezoidal shape, and the back metal feed line is modified into an oblique trapezoidal shape, resulting in the final low RCS Vivaldi antenna.

[0057] As a specific example, step 3 involves designing the designed antenna into an array to form an array antenna, as detailed below:

[0058] Step 3.1: Use simulation software to directly synthesize the simulation data of a single antenna to obtain an approximate array effect. Use this as a reference to obtain the arrangement of the array antennas and find that the optimal element spacing of a single antenna is 21 mm.

[0059] Step 3.2: Since the width of a single antenna is 60 mm, the minimum spacing between antennas placed horizontally along the x-axis is 30 mm. Therefore, the array element antennas are arranged at a 45° angle and the distance between the antennas is controlled at 21 mm, resulting in a horizontal 1×4 one-dimensional linear array.

[0060] Step 3.3: Since the array antenna requires a feeding network to evenly distribute the feeding signal to achieve the array effect, a 1-to-4 Wilkinson power divider is designed for the array elements. By combining the power dividers, the final array antenna is obtained.

[0061] As a specific example, step 4 involves analyzing the surface current of the radiation and scattering states of the array antenna, covering the region with high scattering current with absorbing material, and retaining the high radiation current region in the antenna slot area to reduce RCS and preserve antenna radiation performance, as detailed below:

[0062] Step 4.1: Analyzing the surface current of the array antenna in the radiation and scattering states reveals that the surface current of the array antenna in the radiation and scattering states is mainly concentrated in the exponential slot line region, especially in the near-vertical region and the region near the coplanar stripline feed structure. The current density of the metal layers on both sides is relatively low, and there is also a high current density region in the power divider region. Similarly, the main high current density regions of the antenna in the scattering state are the exponential slot line region and the feed region. However, there are also some regions with relatively high current density in the metal layers on both sides, and there are also some regions with high scattering current in the metal part of the power divider region.

[0063] Step 4.2: Based on the analysis results, cover the shaping areas on both sides of the antenna and the power divider area at the bottom with absorbing material, and retain the high radiation current area of ​​the antenna slot line area, so as to better achieve the purpose of reducing RCS and preserving the antenna radiation performance.

[0064] Step 4.3: For the antenna elements of the array, the scattering is reduced by covering the high scattering current and low radiation current areas at the edges with absorbing material; while for the power divider area, the high scattering current area is directly covered in front of it; the absorbing material is 1.5 mm thick.

[0065] The present invention also provides a low RCS broadband array antenna based on shape modification and absorbing materials, which is designed using the aforementioned design method.

[0066] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0067] Example

[0068] like Figure 1 As shown, this embodiment provides a low RCS broadband array antenna design method based on shape modification and absorbing materials, including the following steps:

[0069] Step 1: Design an ultra-wideband Vivaldi antenna operating in the X-band, as detailed below:

[0070] Design an ultra-wideband Vivaldi antenna that can operate in the X-band. The designed antenna structure and dimensions are as follows: Figure 2 As shown, Figure 2 (a) in the figure is the front view. Figure 2 (b) in the diagram is the rear view. Figure 2 The values ​​of each parameter are shown in Table 1:

[0071] Table 1

[0072]

[0073] The antenna employs a coplanar stripline and microstrip line feeding method, comprising two metal layers and a dielectric substrate in the middle. The top metal layer is the main radiating element of the antenna, containing a radiating element with a double-exponential slot design, a coplanar stripline for matching, and a ground plane. The back side is a microstrip line. The antenna is fed through a 50Ω microstrip line on the back side, and impedance matching is performed between the antenna and the coplanar stripline in the X-band. To achieve better matching, the coplanar stripline on the microstrip line feeding side is shortened to isolate it from the ground plane; that is, the lengths of the coplanar striplines on both sides are unequal, and one end is not directly connected to ground. Figure 2 In (a), line segment b is slightly larger than line segment c.

[0074] Step 2: Analyze the radiation and scattering surface current distribution of the antenna in the X-band, and modify the antenna shape based on the simulation results, as follows:

[0075] Step 2.1: Analyze the radiation and scattering surface current distribution of the antenna in the X-band, such as... Figure 3 As shown, Figure 3 (a) in the diagram represents the radiation state. Figure 3(b) in the diagram represents the scattering state. It can be seen that the high current density region of the antenna in the radiation state is the entire exponential slot line region, especially the region near the transition of the slot line to the vertical region and the coplanar band line feed structure, while the current density of the metal layers on both sides is lower. The main high current density regions of the antenna in the scattering state are also the exponential slot line region and the feed region, but there are also some regions with higher current density in the metal layers on both sides.

[0076] Step 2.2: For the exponential slot line region, directly modifying the metal region may affect the antenna's radiation performance. In order to reduce the RCS as much as possible, the dielectric substrate near the exponential slot line that is not covered by a metal layer can be removed to reduce the RCS. For the metal layer regions on both sides, the current density is relatively small in the radiation state. The metal layer is directly modified by designing comb-shaped hollow metal layers on both sides to reduce the scattering current on both sides.

[0077] Step 2.3: To avoid significantly impacting the antenna's radiation performance during the reshaping process, the antenna's feed section is further optimized. The ground metal layer is modified into an isosceles trapezoidal shape, and the back metal feed line is modified into an oblique trapezoidal shape, resulting in the final low RCS Vivaldi antenna. Figure 4 As shown, Figure 4 (a) in the figure is the front view. Figure 4 (b) in the diagram is the rear view. Figure 4 The values ​​of each parameter are shown in Table 2:

[0078] Table 2

[0079]

[0080] Step 3: The designed antennas are then arrayed to form an array antenna, as detailed below:

[0081] Step 3.1: Use simulation software to directly synthesize the simulation data of a single antenna to obtain an approximate array effect. Use this as a reference to obtain the arrangement of the array antennas and find that the optimal element spacing of a single antenna is 21 mm.

[0082] Step 3.2: Since the width of a single antenna is 60 mm, the minimum spacing between antennas placed laterally along the x-axis is 30 mm. To achieve this spacing, the array element antennas are arranged at a 45° angle, and the distance between the antennas is controlled at 21 mm. The final 1×4 one-dimensional linear array is as follows: Figure 5 As shown;

[0083] Step 3.3: Since the array antenna requires a feeding network to evenly distribute the feeding signal to achieve the array effect, a 1-to-4 Wilkinson power divider is designed for each array element, such as... Figure 6As shown, where L2 = 60 mm, W2 = 80 mm, a2 = 1.8 mm, b2 = 8 mm, c2 = 2.25 mm, d2 = 2.8 mm, e2 = 3.28 mm, blue represents a 180 Ohm resistor, and red represents a 100 Ohm resistor. Figure 6 (a) in the figure is the front view. Figure 6 (b) in the diagram is a rear view. By combining power dividers, the final array antenna is obtained, as shown below. Figure 7 As shown.

[0084] Step 4: Analyze the surface current of the radiation and scattering states of the array antenna, cover the areas with high scattering current with absorbing material, and retain the high radiation current areas in the antenna slot lines to reduce RCS and preserve antenna radiation performance, as detailed below:

[0085] Step 4.1: Analyze the surface current of the array antenna in its radiation and scattering states, such as... Figure 8 The surface current distribution of the array antenna under radiation and scattering conditions is mainly concentrated in the exponential slot line region, especially in the near-vertical region and the region near the coplanar stripline feed structure. The current density of the metal layers on both sides is relatively low, and there is also a high current density region in the power divider region. The main high current density regions of the antenna under scattering conditions are also the exponential slot line region and the feed region, but there are also some regions with relatively high current density in the metal layers on both sides, and there are also some regions with high scattering current in the metal part of the power divider region. From the above analysis, it can be seen that in order to reduce the RCS of the array antenna, it is necessary to control the high scattering current region and avoid the high radiation current region as much as possible.

[0086] Step 4.2: Based on the analysis results, cover the shaping areas on both sides of the antenna and the power divider area at the bottom with absorbing material, and retain the high radiation current area of ​​the antenna slot line area, so as to better achieve the purpose of reducing RCS and preserving the antenna radiation performance.

[0087] Step 4.3: For the antenna elements of the array, scattering is reduced by covering the high-scattering-current and low-radiation-current regions at the edges with absorbing material; while for the power divider region, the high-scattering-current region is directly covered in front of it; for example... Figure 9 The diagram shows a schematic of the antenna covering the absorbing material, where L3 = 32.8 mm, W3 = 70 mm, a3 = 36.3 mm, b3 = 3 mm, and green represents the absorbing material. The parameters of the absorbing material are as follows: Figure 10 As shown, a 1.5mm thick absorbing material was selected. The RCS values ​​of the RAW curves for different thicknesses of absorbing material are compared to those for the material without absorbing material. Figure 11As shown, the RCS reduction performance changes little after the material thickness reaches 1.5 mm. Considering the need to reduce the impact of the absorbing material on the antenna, choosing a 1.5 mm thick absorbing material is a reasonable choice. With a 1.5 mm thick absorbing material, an average RCS reduction of about 5.8 dB can be achieved in the 7 GHz to 13 GHz range, and a maximum RCS reduction of about 12.1 dB can be achieved near 11.4 GHz. Finally, the RCS of the array antenna in the 7 GHz to 13 GHz band is controlled within an average of -24.6 dBsm and a maximum of -19 dBsm.

[0088] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A design method for a low RCS broadband array antenna based on shape modification and absorbing materials, characterized in that, Includes the following steps: Step 1: Design an ultra-wideband Vivaldi antenna operating in the X-band; Step 2: Analyze the radiation and scattering surface current distribution of the antenna in the X-band, and modify the antenna shape based on the simulation results; Step 3: Design the antenna into an array to form an array antenna; Step 4: Analyze the surface current of the radiation and scattering state of the array antenna, cover the area where the scattering current exceeds the threshold with absorbing material, and retain the area in the antenna slot line region where the radiation current is higher than the set value, so as to reduce RCS and retain the antenna radiation performance.

2. The low RCS broadband array antenna design method based on shape modification and absorbing materials according to claim 1, characterized in that, The design described in step 1, operating as an ultra-wideband Vivaldi antenna in the X-band, is as follows: S11. Design an ultra-wideband Vivaldi antenna that operates in the X-band. The antenna adopts a coplanar stripline plus microstripline feeding method and includes a top metal layer, a bottom metal layer and a dielectric substrate between the two. S12, the top metal layer is the main radiating element of the antenna, which includes a radiating element with a double exponential slot line design, a coplanar strip line for matching, and a ground plane; The bottom metal layer is a microstrip line with a characteristic impedance of 50Ω. S13. The antenna is fed through a microstrip line in the bottom metal layer and impedance matched with the radiating element in the X-band via a coplanar strip line. S14. In order to optimize the matching effect, the coplanar strip line on the microstrip line feed side was shortened to isolate the ground. That is, the lengths of the coplanar strip lines on both sides are not the same, and the end corresponding to the microstrip line feed is not connected to the ground.

3. The low RCS broadband array antenna design method based on shape modification and absorbing materials according to claim 1, characterized in that, Step 2 involves analyzing the radiation and scattering surface current distribution of the antenna in the X-band. Based on the simulation results, the antenna is reshaped as follows: S21. Analyze the radiation and scattering surface current distribution of the antenna in the X-band. The high current density region of the antenna in the radiation state is the entire exponential slot line region. The highest density is in the region where the slot line transitions to the vertical region and the coplanar band feed structure, while the current density of the metal layers on both sides is lower. The high current density region of the antenna in the scattering state is also the exponential slot line region and the feed region, but there are also some regions with higher current density in the metal layers on both sides. S22. For the exponential groove area, the RCS is reduced by removing the dielectric substrate near the exponential groove that is not covered by a metal layer; for the metal layer areas on both sides, the metal layer is directly reshaped and comb-shaped metal layer is hollowed out on both sides to reduce the scattering current on both sides. S23. In order to maintain the antenna's radiation performance during the reshaping process, the antenna's feed section is further optimized. The ground plane of the top metal layer is modified into an isosceles trapezoidal shape, and the microstrip line of the bottom metal layer is modified into an oblique trapezoidal shape, resulting in the final low RCS Vivaldi antenna.

4. The low RCS broadband array antenna design method based on shape modification and absorbing materials according to claim 1, characterized in that, Step 3 involves designing the designed antenna into an array to form an array antenna, as detailed below: S31. The simulation data of a single antenna is directly synthesized using simulation software to obtain an approximate array effect. Based on this, the arrangement of the array antenna is obtained, and the optimal element spacing design for a single antenna is 21 mm. S32. Since the width of a single antenna is 60 mm, the minimum spacing between antennas placed horizontally along the x-axis is 30 mm. Therefore, the array element antennas are arranged at a 45° angle and the distance between the antennas is controlled at 21 mm, resulting in a horizontal 1×4 one-dimensional linear array. S33. Since the array antenna requires a feed network to evenly distribute the feed signal to achieve the array effect, a 1-to-4 Wilkinson power divider is designed for the array elements. By combining the power dividers, the final array antenna is obtained.

5. The low RCS broadband array antenna design method based on shape modification and absorbing materials according to claim 1, characterized in that, Step 4 involves analyzing the surface current of the array antenna's radiation and scattering states, covering areas where the scattering current exceeds a threshold with absorbing material, and preserving areas in the antenna slot region where the radiated current is higher than a set value, in order to reduce the RCS and preserve the antenna's radiation performance. Specifically, the steps are as follows: S41. Analyze the surface current of the array antenna in the radiation and scattering states. The surface current of the array antenna in the radiation and scattering states is concentrated in the exponential slot line region. The most concentrated areas are the regions where the slot line transitions to the vertical region and the coplanar stripline feed structure. The current density of the metal layers on both sides is relatively low, and there is also a high current density region in the power divider region. The high current density region of the antenna in the scattering state is also in the exponential slot line region and the feed region. There are also some areas with relatively high current density in the metal layers on both sides, and there is also a high scattering current region in the metal part of the power divider region. S42. Based on the analysis results, cover the shaping areas on both sides of the antenna and the power divider area at the bottom with absorbing material, and retain the high radiation current area of ​​the antenna slot line area to reduce RCS and retain the antenna radiation performance. S43. For the array element part of the array antenna, the scattering is reduced by covering the edge high scattering current and low radiation current regions with absorbing material. For the power divider area, the high scattering current area is directly covered in front of it; the absorbing material is 1.5 mm thick.

6. A low RCS broadband array antenna based on shape modification and absorbing materials, characterized in that, The low RCS broadband array antenna is designed using the design method described in any one of claims 1 to 5.

Images