Design method of broadband dual-polarization low-scattering array antenna

Abstract

The invention discloses a design method of a broadband dual-polarization low-scattering array antenna, and belongs to the technical field of array antenna stealth design. According to the method, the radiation mode of the reference array antenna and the x-polarization and y-polarization broadband scattering modes are calculated and analyzed based on characteristic mode analysis, and then the design of the scattering cancellation unit / low scattering unit is given. And finally, in the co-polarization direction, array antenna co-polarization RCS reduction is realized through scattering cancellation unit array forming. In the cross polarization direction, array antenna cross polarization RCS reduction is achieved through low scattering unit array forming. Through the arrangement mode of the two polarization directions, a two-dimensional array antenna can be formed, and the two-dimensional array antenna is called as a broadband dual-polarization low-scattering array antenna. Therefore, the design of the broadband dual-polarization low-scattering array antenna is realized. The array antenna designed by the invention has the advantages of integration of radiation and scattering, wide band, dual polarization and low scattering, and can meet the stealth requirement.

Description

Technical Field

[0001] The present invention belongs to the technical field of array antenna stealth design. It utilizes a characteristic mode analysis method to guide the design of low-scattering units and scattering cancellation units of the array antenna, and then utilizes two technical means of low-scattering unit array formation and scattering cancellation unit array formation to realize a dual-polarization wide-band RCS reduction design of the array antenna. The present invention is suitable for the research and development of wide-band dual-polarization low-scattering array antennas for stealth platforms. Background Art

[0002] At present, there are several existing technologies in the field of broadband dual-polarization low-scattering design of array antennas, but they all have certain defects in methods and performance:

[0003] 1. Use traditional array unit shaping technology to design low scattering of array antennas. Based on the total current distribution of array antenna units, the scattering current is cut off by performing slot loading at appropriate locations of the array antenna units to achieve RCS reduction design of array antennas. However, for co-polarization, traditional shaping is difficult to achieve RCS reduction, and usually causes the radiation performance of the array antenna to deteriorate, making it difficult to take into account the integrated radiation and scattering design of the array antenna.

[0004] 2. Use metamaterial absorbers, frequency selective surfaces or electromagnetic metasurfaces and other loading technologies, and lay them around the antenna, on the floor or on the covering through reasonable arrangement. Finally, the RCS reduction design of the array antenna can be achieved. However, the above technologies will increase the cross-section or aperture size of the array antenna, that is, the overall size of the antenna will be increased, and it is difficult to achieve in-band RCS reduction.

[0005] 3. Use the scattering cancellation method to design array antenna scattering reduction. This method is to design two array antenna units so that the two units show scattering cancellation characteristics in the x-polarization and y-polarization directions, thereby achieving dual-polarization scattering reduction effects. There are two problems with the above technology: First, the characteristic mode analysis method is not used to find the important scattering modes at each important frequency point in the wide band, so the RCS reduction in the wide band cannot be achieved, that is, the reduction bandwidth is not wide enough (the current widest working bandwidth is 80%). Second, the characteristic mode analysis method is not used to select the important scattering modes of the two polarizations in the wide band, and then a simple and effective shaping design is given based on the current distribution of the important scattering modes of the two polarizations. Therefore, the shaping design is complicated (two scattering cancellation units need to be designed), and the scattering reduction effect is not ideal. Summary of the invention

[0006] The purpose of the present invention is to avoid the deficiencies in the above-mentioned background technology and to propose a design method for a wideband dual-polarization low-scattering array antenna based on characteristic mode analysis.

[0007] The present invention utilizes the scattering cancellation unit array and low scattering unit array method based on characteristic mode analysis, and performs shaping design on the reference array antenna unit, and then scatters and cancels the reference array antenna unit in the same polarization direction (the same polarization direction as the reference array antenna) to form an array, realizing the same polarization wide-band low scattering design. At the same time, the shaping unit itself has the cross-polarization low scattering characteristic, and forms an array in the cross-polarization direction (orthogonal to the polarization direction of the reference array antenna), realizing the cross-polarization wide-band low scattering design. Finally, an array antenna with integrated radiation scattering and wide-band dual-polarization low scattering performance is realized, meeting the stealth requirements of the array antenna.

[0008] The object of the present invention is achieved in that:

[0009] A design method for a broadband dual-polarization low-scattering array antenna comprises the following steps: Step 1: design a reference array antenna according to the radiation performance requirements, analyze the radiation pattern of the reference array element; sort the radiation patterns according to their amplitudes, select important radiation patterns, and calculate their current distributions; select the high current areas that need to be retained according to the current distributions; Step 2, performing scattering pattern analysis on the reference array element, selecting important scattering modes of co-polarization and cross-polarization according to the scattering pattern amplitude, and calculating their phases and current distributions respectively; Step 3, according to the important scattering mode current distribution under two polarizations of the reference array element, compared with the important radiation mode current distribution in step 1, select the strong current part that can be removed or cut, perform modification design on the reference array element, and obtain the designed array element; Step 4, calculating the amplitude and phase of the important scattering mode of the designed array element in the frequency band, and comparing and analyzing the amplitude and phase of the important scattering mode of the reference array element; Step 5, iteratively obtain the co-polarization scattering cancellation unit, calculate the cross-polarization RCS of the designed array element, and compare it with the cross-polarization RCS of the reference array element to confirm that the designed array element can effectively reduce the wideband cross-polarization RCS; Step 6, in the co-polarization direction, the co-polarization RCS reduction of the array antenna is achieved through the design of the cancellation unit array; in the cross-polarization direction, the cross-polarization RCS reduction of the array antenna is achieved through the design of the low-scattering unit array; a two-dimensional array antenna is formed through the array design of the two-directional arrangement; finally, the dual-polarization wideband RCS performance as well as the transmission and radiation performance of the low-scattering array antenna are calculated until the antenna meets the radiation and scattering requirements.

[0010] Furthermore, the step 1 is specifically as follows: Step 1: Design a reference array antenna according to the radiation performance requirements, and use the electromagnetic simulation software HFSS to calculate its radiation performance, including the reflection coefficient Γ and the radiation pattern; use the electromagnetic simulation software FEKO to perform a pattern analysis on the reference array unit radiation pattern within the operating frequency range, including calculating the amplitude and phase of its pattern weight coefficient, the amplitude and phase of the pattern far field, and the pattern current distribution; calculate the pattern amplitude of the radiation pattern based on the pattern weight coefficient and the pattern far field of the radiation pattern , and sort the radiation modes according to the mode amplitude of the radiation mode to select the important radiation modes; according to the mode current distribution of the important radiation modes of the reference array unit, select the strong current area that needs to be retained.

[0011] Furthermore, the step 2 is specifically as follows: Step 2: Use the electromagnetic simulation software FEKO to perform scattering mode analysis on the reference array unit at important frequencies within a wide bandwidth under the same polarization vertical incident plane wave, including calculating the amplitude and phase of its mode weight coefficient, the amplitude and phase of the mode far field, and the mode current distribution; calculate the mode amplitude of the scattering mode based on the mode weight coefficient and mode far field of the scattering mode , and sort the scattering modes according to the mode amplitude of the scattering mode, select the important scattering mode of the same polarization at the important frequency; calculate the phase of the important scattering mode of the same polarization according to the mode weight coefficient and mode far field of the scattering mode , and calculate the current distribution of important scattering modes; use the electromagnetic simulation software FEKO to analyze the scattering mode of the reference array unit at a wide-band important frequency under cross-polarized vertical incident plane waves, including calculating the amplitude and phase of its mode weight coefficient, the amplitude and phase of the mode far field, and the mode current distribution; calculate the mode amplitude of the scattering mode based on the mode weight coefficient and mode far field of the scattering mode , and sort the scattering modes according to their mode amplitudes. At important frequencies, cross-polarized important scattering modes are selected, and the current distribution of important scattering modes is calculated.

[0012] Furthermore, the step 5 is specifically as follows: Step 5: If the effective scattering phase difference of the important scattering modes of the design array unit and the reference array unit is not within the range of 143° to 217° within the wide frequency band, or the scattering amplitudes of the important scattering modes of the two are greatly different, then repeat steps 3 and 4 for the design array unit; continue to perform scattering pattern analysis at frequencies that do not meet the phase difference and amplitude requirements, and then perform modification design on the design array unit, and iterate repeatedly until the effective phase difference of the wide-band important scattering modes of the reference array unit and the latest design array unit is within the range of 143° to 217°, and the scattering amplitudes of the important scattering modes of the two are approximately equal, that is, a co-polarization scattering cancellation unit is obtained; calculate the cross-polarization RCS of the design array unit in the frequency band, and compare it with the cross-polarization RCS of the reference array unit to confirm that the design array unit achieves effective reduction of the wide-band cross-polarization RCS.

[0013] Furthermore, the high current portion that can be removed or cut in step 3 is specifically selected as follows: cutting off the cross-polarization scattering mode current and retaining the radiation mode current.

[0014] Furthermore, the important frequencies in step 2 are selected at equal intervals in the entire wide frequency band.

[0015] Furthermore, in step 2, the co-polarized vertically incident plane wave refers to a vertically incident plane wave with the same polarization as the reference array antenna; and the cross-polarized vertically incident plane wave refers to a vertically incident plane wave orthogonal to the polarization direction of the reference array antenna.

[0016] Furthermore, in step 4, the mode amplitude of the important scattering mode of the designed array unit in the frequency band is calculated. and Phase , and compared with the pattern amplitude and phase of the important scattering mode of the reference array unit; within this frequency band, if the effective scattering phase difference of the two units is , and at the same time their scattering amplitudes are basically equal, , the designed array unit is called the scattering cancellation unit of the co-polarization reference array unit.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention proposes a design method for a wideband dual-polarization low-scattering array antenna based on characteristic mode analysis. By loading the radiation patch gap, the co-polarization scattering cancellation unit design and the cross-polarization low-scattering unit design can be simultaneously realized. Then, by arranging the scattering cancellation units in the co-polarization direction and the low-scattering units in the cross-polarization direction, the design of a wideband dual-polarization low-scattering array antenna is realized. The RCS reduction design idea is clear, and the design method is simple and efficient.

[0019] 2. Compared with other works, the present invention does not damage the radiation performance, does not increase the overall size of the antenna, and has a wider co-polarization RCS reduction bandwidth (100%, including the antenna operating frequency band) and cross-polarization RCS reduction bandwidth (88%, including the antenna operating frequency band). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is an exploded diagram of the reference array antenna unit.

[0021] Figure 2 It is a top view of the reference array antenna unit (first layer of metal patch).

[0022] Figure 3 is a front view of the reference array antenna unit.

[0023] Figure 4 is a side view of the reference array antenna element.

[0024] Figure 5 Reference array antenna schematic.

[0025] Figure 6 It is the calculation result of the reference array antenna reflection coefficient curve.

[0026] Figure 7 It is the calculated result of the radiation pattern of the reference array antenna at 4.5 GHz.

[0027] Figure 8 is the calculated radiation pattern amplitude of the reference array element.

[0028] Fig. 9 is the calculated result of the radiation mode 2 current of the reference array element.

[0029] Fig.10 is the calculated result of the radiation mode 6 current of the reference array element.

[0030] Fig.11 It is the calculation result of the amplitude of the reference array unit polarization scattering mode at the typical frequency point x.

[0031] Fig.12 are the calculation results of the x-polarized scattering mode 1 and scattering mode 6 currents of the reference array unit.

[0032] Fig.13 It is the calculation result of the y-polarization scattering mode amplitude of the reference array unit at the typical frequency point.

[0033] Fig.14 are the calculation results of the y-polarized scattering mode 1, scattering mode 2, and scattering mode 3 currents of the reference array unit.

[0034] Fig.15It is a schematic diagram of the radiation patch layer structure of the reference array unit.

[0035] Fig.16 It is a schematic diagram of the radiation patch layer structure of the low RCS scattering cancellation unit.

[0036] Fig.17 It is the calculation result of the amplitude of the x-polarization important scattering mode 1 and scattering mode 6 of the reference unit and the cancellation unit.

[0037] Fig.18 It is the calculation result of the phase difference between the x-polarization important scattering mode 1 and scattering mode 6 of the reference unit and the destructive unit.

[0038] Fig.19 It is a schematic diagram of the radiation patch layer structure of a wideband dual-polarization low-scattering array antenna.

[0039] Fig. 20 It is the co-polarization RCS calculation result of the reference array antenna and the wideband dual-polarization low-scattering array antenna.

[0040] Fig.21 It is the cross-polarization RCS calculation result of the reference array antenna and the wideband dual-polarization low-scattering array antenna.

[0041] Fig. 22 It is the calculation result of the reflection coefficient curve of the reference array antenna and the wideband dual-polarization low-scattering array antenna.

[0042] Fig.23 It is the calculated radiation pattern result of the reference array antenna and the wideband dual-polarization low-scattering array antenna at 4.5 GHz. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0044] A broadband dual-polarization low-scattering array antenna design method based on characteristic mode analysis includes the following steps:

[0045] Step 1: Design a reference array antenna according to the radiation performance requirements, and use the electromagnetic simulation software HFSS to calculate its radiation performance, including the reflection coefficient Γ and the radiation pattern. Use the electromagnetic simulation software FEKO to perform a pattern analysis on the reference array unit radiation pattern within the operating frequency range, including calculating the amplitude and phase of its pattern weight coefficient, the amplitude and phase of the pattern far field, and the pattern current distribution; calculate the pattern amplitude of the radiation pattern based on the pattern weight coefficient and pattern far field of the radiation pattern , and sort the radiation modes according to the mode amplitude of the radiation mode to select the important radiation mode; according to the mode current distribution of the important radiation mode of the reference array unit, select the strong current area that needs to be retained;

[0046] Step 2, using electromagnetic simulation software FEKO, the co-polarization scattering mode analysis (the plane wave incident condition is vertical incidence, and the polarization form is the same as the reference array antenna polarization, referred to as co-polarization) of the important frequencies (the important frequencies in the present invention are selected at equal intervals within the entire wide band) in the reference array unit wide band, including calculating the amplitude and phase of its mode weight coefficient, the amplitude and phase of the mode far field, and the mode current distribution; according to the mode weight coefficient and mode far field of the scattering mode, the mode amplitude of the scattering mode is calculated , and sort the scattering modes according to the mode amplitude of the scattering mode, and select the co-polarization important scattering mode at the important frequency. According to the mode weight coefficient of the scattering mode and the mode far field, calculate the phase of the co-polarization important scattering mode ; Using the electromagnetic simulation software FEKO, the cross-polarization scattering pattern of the wide-band important frequency of the reference array unit is analyzed (the plane wave incident condition is vertical incidence, and the polarization form is orthogonal to the polarization of the reference array antenna, referred to as cross-polarization), including calculating the amplitude and phase of its mode weight coefficient, the amplitude and phase of the mode far field, and the mode current distribution; according to the mode weight coefficient and mode far field of the scattering mode, the mode amplitude of the scattering mode is calculated , and sort the scattering modes according to their mode amplitudes, and select cross-polarized important scattering modes at important frequencies;

[0047] Step 3: According to the mode current distribution of important scattering modes under two polarizations (co-polarization and cross-polarization) of the reference array unit, compare the mode current distribution of important radiation modes in step 1, select the strong current part that can be removed or cut (cut off the cross-polarization scattering mode current and retain the radiation mode current), perform a modification design on the reference array unit, and obtain the designed array unit.

[0048] Step 4: Calculate the amplitude of the important scattering mode of the designed array unit in this frequency band and Phase (Plane wave incident conditions are vertical incidence, co-polarization), and compared with the mode amplitude and phase of the important scattering mode of the reference array unit. In this frequency band, if the effective scattering phase difference of the two units is , and at the same time their scattering amplitudes are basically equal, , then the designed unit is called the scattering cancellation unit of the co-polarization reference array unit; in this wide band, if the effective scattering phase difference of the important scattering modes of the two units is not within the range of 143°~217°, or the scattering amplitudes of the two important scattering modes are greatly different, then repeat steps 3 and 4 for the designed unit, continue to analyze the scattering mode at the frequency that does not meet the phase difference and amplitude requirements, and then perform modification design on the designed unit, and iterate repeatedly until the effective phase difference of the broadband important scattering modes of the reference array unit and the latest designed unit is within the range of 143°~217°, and the scattering amplitudes of the two important scattering modes are approximately equal, then the co-polarization scattering cancellation unit can be obtained. Calculate the RCS of the designed array unit in this frequency band (the plane wave incident condition is vertical incidence, cross-polarization), and compare it with the RCS of the reference array unit to confirm that the designed array unit can achieve effective reduction of broadband cross-polarization RCS. Therefore, the designed unit can achieve both scattering field cancellation of the co-polarization and reference array units and cross-polarization RCS reduction.

[0049] Step 5. In the co-polarization direction, the co-polarization RCS reduction of the array antenna is achieved by the array design of the cancellation units (reference array units and design array units); in the cross-polarization direction, the cross-polarization RCS reduction of the array antenna is achieved by the array design of the low-scattering units (design array units). By designing the array in the above-mentioned co-polarization and cross-polarization directions, a two-dimensional array antenna can be formed, which is called a wide-band dual-polarization low-scattering array antenna. Finally, the dual-polarization wide-band RCS performance and the transmission and radiation performance (including the reflection coefficient Γ, gain and radiation pattern, etc.) of the low-scattering array antenna are calculated until the antenna meets the radiation and scattering requirements.

[0050] Here is a specific example of broadband dual-polarization low-scattering array antenna design:

[0051] First, a schematic diagram of the reference array unit structure is given, as shown in Figures 1 to Figure 5As shown, it includes a radiation patch, a dielectric substrate, a metal floor layer, a floor gap, a metal feed microstrip line, and a coaxial feed structure. The radiation patch is printed on the upper surface of the dielectric substrate, and the metal bottom plate is printed on the lower surface, and the metal floor is etched with a gap; the metal feed microstrip line is in the middle of the dielectric substrate; and the L-shaped feeding structure is used to excite the antenna radiation. The dielectric plate has a side length of L1 and a thickness of H. The radiation patch is circular with a diameter of D1. The side length of the metal floor is L1. The geometric center of the coupling aperture is consistent with the geometric center of the metal floor, with a length of L2 in the Y direction and a width of W2 in the X direction. The coaxial metal column is located on the X axis, with a distance of X1 from the geometric center of the metal floor, a diameter of D2, and a height of H / 2. The microstrip feed line is located in the middle of the dielectric plate, with a length of L3 and a width of D2. The reference array antenna was calculated using the electromagnetic simulation software HFSS, and the results showed that the antenna has good transmission performance and radiation performance. In the frequency range of 3.0GHz-9.0GHz, the calculated curve of the reflection coefficient of the reference array antenna is shown in Figure 6, where the horizontal axis represents the frequency in GHz. The vertical axis is the reflection coefficient Γ in dB. The figure shows the calculation results of the reference array antenna Γ, which shows that the reflection coefficient of the reference array antenna is better than -10 dB in the 4.12GHz-5.78GHz band, and has good transmission performance. The radiation pattern calculated at 4.5GHz by the reference array antenna is shown in Figure 7, where the horizontal axis represents the angle in deg. The vertical axis is the actual gain in dBi. The black solid line in the figure is the radiation pattern calculated by the reference array antenna on the phi=0° plane, and the red dotted line is the radiation pattern calculated by the reference array antenna on the phi=90° plane. The results show that the reference array antenna has good radiation performance at 4.5GHz, with a normal gain of 15.9dBi. The radiation pattern of the reference array unit was analyzed using the electromagnetic simulation software FEKO. The radiation pattern amplitude of the reference array unit at 4.5 GHz is shown in Figure 8, where the horizontal axis represents the mode number and the vertical axis represents the mode amplitude in units of 10. -3 v / m. It can be seen that the reference array unit has 12 radiation modes, among which the mode amplitudes of radiation mode 2 and radiation mode 6 are much larger than those of other radiation modes, that is, the heavy radiation modes of the reference array unit are mode 2 and mode 6. Then the current distribution of the main radiation modes 2 and 6 is calculated, and the results are shown in Figures 9 and Fig.10As shown in the figure, the red arrow indicates the direction of current flow, and the color indicates the current distribution intensity, in A / m. From the calculation results, it can be seen that the upper part shows the current distribution of the main radiation modes 2 and 6 on the radiation patch. The distribution is strong on the left and right sides of the patch and flows along the x direction. Therefore, the reference array antenna radiation electric field of the present invention is in the x-polarization direction, that is, the reference array antenna polarization is x-polarization. Therefore, when performing the reference array unit scattering pattern analysis and low scattering / scattering destructive design below, the x-polarized plane wave incident is the same polarized plane wave incident, and the y-polarized plane wave incident is the cross-polarized plane wave incident.

[0052] Next, the scattering pattern of the reference array element is analyzed, and then a broadband dual-polarization low-scattering design is performed:

[0053] According to the requirements of broadband dual-polarization stealth, the electromagnetic simulation software FEKO is used to analyze the scattering patterns of the reference array elements in x-polarization and y-polarization at broadband important frequencies (3GHz, 4 GHz, 5 GHz, 6 GHz, 7 GHz, 8 GHz and 9 GHz), including the amplitude and phase of its mode weight coefficient, the amplitude and phase of the mode far field, and the mode current distribution; the mode amplitude of the scattering mode is calculated based on the mode weight coefficient and mode far field of the scattering mode , and sort the scattering modes according to their mode amplitudes, and select important scattering modes at important frequencies (3 GHz, 4 GHz, 5 GHz, 6 GHz, 7 GHz, 8 GHz, and 9 GHz). As shown in Figure 11, the x-polarized scattering mode amplitude calculation results of the reference array unit at important frequencies (3 GHz, 4 GHz, 5 GHz, 6 GHz, 7 GHz, 8 GHz, and 9 GHz) are shown, where the x-axis is the incident frequency in GHz. The y-axis is the mode number. The z-axis is the mode amplitude in 10 -3 v / m. According to the calculation results, scattering mode 1 is an important scattering mode in the low frequency range of 3 GHz-4 GHz, and scattering mode 6 is an important scattering mode in the high frequency range of 5 GHz-9 GHz. The current distribution of x-polarized scattering mode 1 and mode 6 is calculated below. The results are as follows: Fig.12 The red arrow in the current diagram indicates the direction of current flow, and the color indicates the current distribution intensity in A / m.

[0054] As shown in Figure 13, the calculation results of the y-polarized scattering mode amplitude of the reference array element at important frequencies (3 GHz, 4 GHz, 5 GHz, 6 GHz, 7 GHz, 8 GHz and 9 GHz) are shown, where the x-axis is the incident frequency in GHz. The y-axis is the mode number. The z-axis is the mode amplitude in 10 -3v / m. According to the calculation results, it can be seen that scattering mode 1 is an important scattering mode in the low-frequency region of 3GHz-4 GHz, scattering mode 2 is an important scattering mode in the medium-frequency region of 4 GHz-5 GHz, and scattering mode 3 is an important scattering mode in the high-frequency region of 6 GHz-9 GHz. The current distribution of y-polarized scattering mode 1, scattering mode 2 and scattering mode 3 is calculated below, and the results are shown in Figure 14. The red arrow in the current diagram indicates the direction of current flow, and the color indicates the current distribution intensity, in units of A / m. According to the current distribution of x-polarized scattering mode 1, mode 6 and y-polarized scattering mode 1, scattering mode 2 and scattering mode 3 in various parts of the antenna, compare the mode current distribution of important radiation mode 2 and mode 6 in step 1, select the current part that can be removed or cut (cut off the y-polarized scattering mode current and retain the radiation mode current), and perform a reshaping design on the antenna. Make the following reshaping design:

[0055] On the first layer of radiation patches, three straight slots are loaded along the x-axis direction to introduce an effective phase difference with the x-polarized scattering field of the reference array unit (reducing the x-polarized RCS through scattering cancellation) and to cut off the y-polarized scattering mode current (reducing the y-polarized RCS). The structure of the reference array unit and the low RCS / scattering cancellation unit is shown in Figure 15- Fig.16 As shown, (a) is the reference array element, and (b) is the low RCS / scattering cancellation element. Figure 17 further shows the amplitudes of the x-polarized scattering modes 1 and 6 of the reference array element and the low RCS / scattering cancellation element, where the black solid line is the amplitude calculation result of the mode 1 of the reference array element, the red dashed line is the amplitude calculation result of the mode 1 of the low RCS scattering cancellation element, the blue dashed line is the amplitude calculation result of the mode 6 of the reference array element, and the pink dashed line is the amplitude calculation result of the mode 6 of the low RCS scattering cancellation element. The results show that within the frequency band of 3 GHz-4 GHz, the amplitudes of the x-polarized scattering mode 1 of the reference array element and the low RCS / scattering cancellation element are almost equal and are the main scattering mode. Within the frequency band of 4 GHz-9 GHz, the amplitudes of the x-polarized scattering mode 6 of the reference array element and the low RCS / scattering cancellation element are almost equal and are the main scattering mode. Figure 18 shows the calculated results of the mode phase difference of the x-polarization scattering mode 1 and mode 6 of the reference array unit and the low RCS scattering / destruction unit, where the blue solid line is the calculated result of the phase difference of mode 1, and the red dotted line is the calculated result of the phase difference of mode 6. The results show that within 4 GHz-4.5 GHz, the x-polarization scattering mode 1 of the reference array unit and the low RCS scattering / destruction unit achieves an effective phase difference, and within 4.5 GHz-9 GHz, the x-polarization scattering mode 6 of the reference array unit and the low RCS scattering / destruction unit achieves an effective phase difference.

[0056] Finally, the reference array unit and the low RCS scattering / destruction unit are reasonably arranged and designed. In the x-polarization direction, the reference array unit and the destructive unit form an array to achieve the co-polarization RCS reduction of the array antenna; in the y-polarization direction, the low scattering array is used to form an array to achieve the cross-polarization RCS reduction of the array antenna. By forming an array in the above-mentioned x and y directions, a two-dimensional array antenna can be formed, thereby obtaining a wide-band dual-polarization low-scattering array antenna, and its radiation patch layer structure schematic diagram is shown in Figure 19.

[0057] Through the modification design of the reference array unit radiation patch and the reasonable array design, a broadband dual-polarization low-scattering array antenna was finally realized. The broadband x-polarization RCS calculation results of the broadband dual-polarization low-scattering array antenna and the reference array antenna are shown in Fig. 20 The calculation results of the broadband y-polarization RCS of the broadband dual-polarization low-scattering array antenna and the reference array antenna are shown in Figure 21. The calculation results of the reflection coefficient curve of the broadband dual-polarization low-scattering array antenna are shown in Figure 22. The calculation results of the radiation pattern of the broadband dual-polarization low-scattering array antenna at 4.5 GHz are shown in Figure 23.

[0058] Based on the above calculation results, it can be seen that the mode analysis is based on the characteristic mode theory, the mode amplitude is used to select the important scattering mode, and the current distribution of the important radiation mode and the wideband x-polarization and y-polarization scattering mode is compared to determine the slot position and size. With the help of slot loading, the x-polarization (co-polarization) scattering cancellation and y-polarization (cross-polarization) scattering mode suppression can be achieved, which can effectively achieve the wideband dual-polarization RCS reduction of the array antenna. Compared with the reference array antenna, the wideband dual-polarization low-scattering array antenna can achieve the x-polarization RCS reduction bandwidth (100%, including the antenna working band) and the y-polarization RCS reduction bandwidth (88%, including the antenna working band), the average co-polarization reduction value is 8.0 dB, the average cross-polarization reduction value is 7.6 dB, and the average in-band RCS reduction is 19 dB. And the radiation performance of the array antenna remains good. And from the calculation results in Figures 22 and 23, compared with the reference array antenna, the transmission performance and radiation performance of the wideband dual-polarization low-scattering array antenna remain good, without significant changes.

[0059] In summary, the present invention realizes the separation of radiation mode and scattering mode based on characteristic mode analysis, ensures that the radiation mode is not affected, performs scattering analysis on typical frequency points within the dual-polarization wide-band range, and selects x-polarization wide-band important scattering mode and y-polarization wide-band important scattering mode according to the scattering mode amplitude. Then, the important radiation mode current and the x-polarization wide-band important scattering mode and y-polarization wide-band important scattering mode current are compared, and the x-polarization scattering cancellation unit and y-polarization low scattering unit design are realized simultaneously through slot loading, and then the reference array unit and scattering cancellation unit array design are realized in the x-polarization (co-polarization) direction, and the low scattering unit array design is realized in the y-polarization (cross-polarization) direction, so as to realize the design of broadband dual-polarization low scattering array antenna.

[0060] It should be noted that the above description is only a preferred application example of the present invention and is not intended to limit the protection scope of the present invention. Any technical solution using equivalent replacement or equivalent transformation is within the protection scope of the present invention.

Claims

1. A design method for a broadband dual-polarization low-scattering array antenna, characterized in that: The specific steps include: Step 1: design a reference array antenna according to the radiation performance requirements, analyze the radiation pattern of the reference array element; sort the radiation patterns according to their amplitudes, select important radiation patterns, and calculate their current distributions; select the high current areas that need to be retained according to the current distributions; Step 2, performing scattering pattern analysis on the reference array element, selecting important scattering modes of co-polarization and cross-polarization according to the scattering pattern amplitude, and calculating their phases and current distributions respectively; Step 3, according to the important scattering mode current distribution under two polarizations of the reference array element, compared with the important radiation mode current distribution in step 1, select the strong current part that can be removed or cut, perform modification design on the reference array element, and obtain the designed array element; Step 4, calculate the amplitude and phase of the important scattering mode of the designed array element in the wide frequency band, and compare and analyze them with the amplitude and phase of the important scattering mode of the reference array element; Step 5, iteratively obtain the co-polarization scattering cancellation unit, calculate the cross-polarization RCS of the designed array element, and compare it with the cross-polarization RCS of the reference array element to confirm that the designed array element can effectively reduce the wideband cross-polarization RCS; Step 6, in the co-polarization direction, the co-polarization RCS reduction of the array antenna is achieved through the design of the cancellation unit array; in the cross-polarization direction, the cross-polarization RCS reduction of the array antenna is achieved through the design of the low-scattering unit array; a two-dimensional array antenna is formed through the array design of the two-directional arrangement; finally, the dual-polarization wideband RCS performance as well as the transmission and radiation performance of the low-scattering array antenna are calculated until the antenna meets the radiation and scattering requirements.

2. The design method of a broadband dual-polarization low-scattering array antenna according to claim 1, characterized in that: The step 1 is specifically as follows: Step 1, design a reference array antenna according to the radiation performance requirements, and use electromagnetic simulation software HFSS to calculate its radiation performance, including reflection coefficient Γ and radiation pattern; Using electromagnetic simulation software FEKO, the radiation pattern of the reference array unit is analyzed within the operating frequency range, including the calculation of the amplitude and phase of its mode weight coefficient, the amplitude and phase of the mode far field, and the mode current distribution; Based on the mode weight coefficient of the radiation mode and the mode far field, the mode amplitude of the radiation mode is calculated , and sort the radiation modes according to the mode amplitude of the radiation modes, and select the important radiation modes; According to the mode current distribution of the important radiation mode of the reference array unit, the strong current area to be retained is selected.

3. The design method of a broadband dual-polarization low-scattering array antenna according to claim 1, characterized in that: The step 2 is specifically as follows: Step 2, using electromagnetic simulation software FEKO, under co-polarized vertical incident plane waves, the scattering pattern analysis of the reference array unit is performed at important frequencies within a wide band, including calculating the amplitude and phase of its mode weight coefficient, the amplitude and phase of the mode far field, and the mode current distribution; The mode amplitude of the scattering mode is calculated based on the mode weight coefficient and mode far field of the scattering mode. , and sort the scattering modes according to the mode amplitude of the scattering mode, select the important scattering mode of the same polarization at the important frequency; calculate the phase of the important scattering mode of the same polarization according to the mode weight coefficient and mode far field of the scattering mode , and calculate the current distribution of important scattering modes at the same time; using the electromagnetic simulation software FEKO, under cross-polarized vertical incident plane waves, the scattering mode analysis of the reference array unit is performed at important frequencies in a wide bandwidth, including calculating the amplitude and phase of its mode weight coefficient, the amplitude and phase of the mode far field, and the mode current distribution; The mode amplitude of the scattering mode is calculated based on the mode weight coefficient and mode far field of the scattering mode. , and sort the scattering modes according to their mode amplitudes. At important frequencies, cross-polarized important scattering modes are selected, and the current distribution of important scattering modes is calculated.

4. The design method of a broadband dual-polarization low-scattering array antenna according to claim 1, characterized in that: The step 5 is specifically as follows: Step 5: If the effective scattering phase difference of the important scattering modes of the design array unit and the reference array unit is not within the range of 143° to 217° within the wide frequency band, or the scattering amplitudes of the important scattering modes of the two are greatly different, then repeat steps 3 and 4 for the design array unit; continue to perform scattering pattern analysis at frequencies that do not meet the phase difference and amplitude requirements, and then perform modification design on the design array unit, and iterate repeatedly until the effective phase difference of the wide-band important scattering modes of the reference array unit and the latest design array unit is within the range of 143° to 217°, and the scattering amplitudes of the important scattering modes of the two are approximately equal, that is, a co-polarization scattering cancellation unit is obtained; calculate the cross-polarization RCS of the design array unit in the wide frequency band, and compare it with the cross-polarization RCS of the reference array unit to confirm that the design array unit achieves effective reduction of the wide-band cross-polarization RCS.

5. The design method of a broadband dual-polarization low-scattering array antenna according to claim 1, characterized in that: The high current portion that can be removed or cut in step 3 is specifically selected as follows: cutting off the cross-polarization scattering mode current and retaining the radiation mode current.

6. The design method of a broadband dual-polarization low-scattering array antenna according to claim 1, characterized in that: The important frequencies in step 2 are selected at equal intervals throughout the wide frequency band.

7. The design method of a broadband dual-polarization low-scattering array antenna according to claim 1, characterized in that: In step 2, the co-polarized vertically incident plane wave refers to a vertically incident plane wave with the same polarization as the reference array antenna; the cross-polarized vertically incident plane wave refers to a vertically incident plane wave orthogonal to the polarization direction of the reference array antenna.

8. The design method of a broadband dual-polarization low-scattering array antenna according to claim 1, characterized in that: In step 4, the amplitude of the important scattering mode of the designed array element in this wide frequency band is calculated. and Phase , and compared with the mode amplitude and phase of the important scattering mode of the reference array unit; within this wide frequency band, if the effective scattering phase difference of the two units is , and at the same time their scattering amplitudes are basically equal, , the designed array unit is called the scattering cancellation unit of the co-polarization reference array unit.

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