Disclosure of Invention
The invention aims to design a low radar scattering cross section reflective array antenna based on artificial surface plasmons aiming at the defects in the prior art, so as to improve the frequency band range and the angular domain range of radar scattering cross section reduction on the premise of ensuring good radiation performance of the antenna.
In order to achieve the purpose, the low radar scattering cross section reflective array antenna based on the artificial surface plasmon comprises a feed source 1 and a reflective array surface 2, wherein the reflective array surface 2 is composed of M multiplied by N reflecting units 3 with the same structure and different parameters, and is characterized in that:
the reflection unit 3 adopts a cross structure, namely a three-dimensional artificial surface plasmon structure formed by crisscrossing a first laminated dielectric slab 31 and a second laminated dielectric slab 32;
the first laminated dielectric plate 31 is composed of a first dielectric substrate 311, a second dielectric substrate 312, a first left metal surface 313 and a first right metal surface 314 printed on two sides of the surface of the first dielectric substrate 311, and the metal-printed surface of the first dielectric substrate 311 is adhered to the second dielectric substrate 312;
the second laminated dielectric plate 32 is composed of a third dielectric substrate 321, a fourth dielectric substrate 322, and a second left metal surface 323 and a second right metal surface 324 printed on both sides of the surface of the third dielectric substrate 321, and the metal-printed surface of the third dielectric substrate 321 is adhered to the fourth dielectric substrate 322.
Further, the first dielectric substrate 311, the second dielectric substrate 312, the third dielectric substrate 321 and the fourth dielectric substrate 322 are all rectangular, a first upper rectangular through groove 3111 is formed above the center of the first dielectric substrate 311, and a second upper rectangular through groove 3121 is formed above the center of the second dielectric substrate 312; a first lower rectangular through groove 3211 is formed below the center of the third dielectric substrate 321, and a second lower rectangular through groove 3221 is formed below the center of the fourth dielectric substrate 322;
further, the first upper rectangular through groove 3111 is attached to the second upper rectangular through groove 3121, the first lower rectangular through groove 3211 is attached to the second lower rectangular through groove 3221, and the upper and lower rectangular through grooves are vertically disposed to form a cross structure.
Further, the first left metal surface 313 is composed of upper metal branches 3131, lower metal branches 3132, and metal branches 313;
further, the first right metal surface 314, the second left metal surface 323, the second right metal surface 324 and the first left metal surface 313 are identical in structure and are respectively obtained by rotating the first left metal surface 313 by 180 degrees around the central axis of the cross structure, by 90 degrees clockwise, and by 90 degrees counterclockwise.
Further, the upper metal branch 3131 is composed of three rectangular metal patches with the same size, the three metal patches are arranged in parallel from bottom to top, and the distance between two adjacent patches is the same;
further, the lower metal branch 3132 is located below the upper metal branch 3131, and is formed by five rectangular metal patches with the same size, wherein the five metal patches are arranged in parallel from bottom to top, and the distance between two adjacent metal patches is the same;
further, the metal branch 3133 is a rectangular metal post, and is located at one end of the three metal patches of the upper metal branch 3131 and the five metal patches of the lower metal branch 3132, so as to connect the eight metal patches.
Further, the lengths L of the three metal patches in the upper metal stub 3131 of each reflection unit 3 are determined by the reflection phase value of that reflection unit 3; the size of the five metal patches in the lower metal branch 3132 of each reflection unit 3 is independent of the reflection phase value of the reflection unit 3, i.e. the size of the lower metal branch 3132 in each reflection unit 3 is the same; the size of the metal branch 3133 of each reflection unit 3 is independent of the reflection phase value of the reflection unit 3, i.e. the size of the metal branch 3133 in each reflection unit 3 is the same.
Compared with the prior art, the invention has the following advantages:
first, the invention uses the reflection array plane formed by M multiplied by N reflection units with different reflection phases, within the working frequency band, the spherical electromagnetic wave radiated by the feed source can be reflected into the plane electromagnetic wave, thus ensuring the radiation gain of the reflection array antenna, and outside the working frequency band, the radar detection wave can penetrate through the reflection array plane, thus the reflection array antenna has the characteristic of low radar scattering cross section.
Secondly, the reflection unit of the invention adopts a three-dimensional artificial surface plasmon structure formed by crisscross of two laminated dielectric substrates with the same structure, so that two polarized electromagnetic waves can be regulated and controlled;
thirdly, the laminated dielectric substrate of the invention is provided with four metal surfaces, and each metal surface comprises a lower metal branch and an upper metal branch. Because the lower metal branch can save energy to enable the reflection unit to generate band elimination characteristics, the reflection unit has the characteristic of high reflection coefficient within the working frequency band range, the radiation efficiency of the reflection array antenna is ensured, and the reflection unit has the characteristic of high wave transmission efficiency outside the working frequency band range, so that radar detection wave energy can penetrate through the reflection unit; meanwhile, when the reflection phase of the reflection unit is adjusted, the upper metal branch has small influence on the reflection and transmission characteristics of the reflection unit, so that the reflection units with different reflection phases have high reflection coefficients in a working frequency band and have high transmission coefficients outside the working frequency band.
Detailed Description
The following describes in detail specific embodiments and effects of the present invention with reference to the drawings.
Referring to fig. 1, four examples are given as follows:
example 1
The embodiment comprises a feed source 1 and a reflection array surface 2, wherein the beam width of the feed source 1 is 40 degrees, the reflection array surface 2 is positioned right below the feed source 1, the distance f between the reflection array surface 2 and the phase center of the feed source 1 is 165.0mm, and the reflection array surface 2 is composed of 14 multiplied by 14 reflection units 3 with the same structure and different parameters. Each of the reflecting units 3 is cross-shaped by a first laminated dielectric plate 31 and a second laminated dielectric plate 32 to constitute a three-dimensional artificial surface plasmon structure, as shown in fig. 2.
The reflection phase of each reflection cell 3 in the reflection front 2 is determined by the following formula:
wherein phi isiIs the reflection phase of the ith reflection unit 3, wherein i is from 1 to 14 x 14, the operating wavelength λ in free space is 30.0mm, RiIs the distance from the phase center of the feed 1 to the center of the i-th reflection unit 3, riIs a vector pointing from the center of the reflection array 2 to the center of the ith reflection unit 3, and is a unit vector r along the radiation direction of the reflection array antenna0=(0,0,0),φ0Take 0.
Referring to fig. 3, the first laminated medium 31 of each reflection unit 3 is composed of a first medium substrate 311, a second medium substrate 312, and a first left metal surface 313 and a first right metal surface 314 printed on both sides of the surface of the first medium substrate 311, and the metal-printed surface of the first medium substrate 311 is adhered to the second medium substrate 312; the second laminated dielectric plate 32 of each reflecting unit 3 is composed of a third dielectric substrate 321, a fourth dielectric substrate 322, and a second left metal face 323 and a second right metal face 324 printed on both sides of the surface of the third dielectric substrate 321, and the metal-printed face of the third dielectric substrate 321 is adhered to the fourth dielectric substrate 322.
The first right metal surface 314, the second left metal surface 323, the second right metal surface 324 and the first left metal surface 313 are all the same in structure, that is, the first right metal surface 314 is formed by rotating the first left metal surface 313 by 180 degrees around the central axis of the crisscross structure, the second left metal surface 323 is formed by rotating the first left metal surface 313 by 90 degrees clockwise around the central axis of the crisscross structure, and the second right metal surface 324 is formed by rotating the first left metal surface 313 by 90 degrees counterclockwise around the central axis of the crisscross structure;
the first dielectric substrate 311, the second dielectric substrate 312, the third dielectric substrate 321 and the fourth dielectric substrate 322 are all rectangular, a first upper rectangular through groove 3111 is formed above the center of the first dielectric substrate 311, and a second upper rectangular through groove 3121 is formed above the center of the second dielectric substrate 312; a first lower rectangular through groove 3211 is formed below the center of the third dielectric substrate 321, and a second lower rectangular through groove 3221 is formed below the center of the fourth dielectric substrate 322;
the first upper rectangular through groove 3111 is attached to the second upper rectangular through groove 3121, and the first lower rectangular through groove 3211 is attached to the second lower rectangular through groove 3221; the two attached upper rectangular through grooves and the two attached lower rectangular through grooves are vertically arranged, and finally a cross structure as shown in fig. 2 is formed.
The first dielectric substrate 311, the second dielectric substrate 312, the third dielectric substrate 321 and the fourth dielectric substrate 322 are all rectangular plates with a relative dielectric constant of 2.2, the thickness t of each rectangular plate is 0.5mm, the length w of each rectangular plate is 17.0mm, and the height h of each rectangular plate is 8.0 mm; in fig. 3, the first upper rectangular through groove 3111, the second upper rectangular through groove 3121, the first lower rectangular through groove 3211, and the first lower rectangular through groove 3221 are all 4.0mm in height by 0.5 × h, and 1.0mm in width by 2 × t.
Referring to fig. 4, first left metal surface 313 is composed of upper metal branch 3131, lower metal branch 3132, and metal stem 3133; wherein the upper metal branch 3131 is composed of three rectangular metal patches with the same size, the three metal patches are arranged in parallel from bottom to top, and the distance between two adjacent patches is the same; the lower metal branch 3132 is located below the upper metal branch 3131 and is formed by five rectangular metal patches with the same size, the five metal patches are arranged in parallel from bottom to top, and the distance between two adjacent patches is the same; the metal branch 3133 is a rectangular metal post, and is located at one end of the three metal patches of the upper metal branch 3131 and the five metal patches of the lower metal branch 3132, so as to connect the eight metal patches.
The distances g between the three metal patches in the upper metal branch 3131 are all 0.5mm, the width b of each metal patch is 0.5mm, the lengths L are all equal, and the lengths L of the three metal patches are determined by the reflection phase of the reflection unit 3 to obtain each reflection sheetPhi is a unitiLength L of upper metal branch of four metal surfacesiAnd its reflection phase phiiIs shown as a solid line in fig. 5.
The distances g between the five metal patches in the lower metal branch 3132 are all 0.5mm, the width b of each metal patch is 0.5mm, the length a of each metal patch is 6.0mm, and the size of the five metal patches in the lower metal branch 3132 of each reflection unit 3 is independent of the reflection phase value of the reflection unit 3, i.e. the size of the lower metal branch 3132 in each reflection unit 3 is the same; the distance g between the lower metal branch 3132 and the upper metal branch 3131 is 0.5 mm;
the width b and height 8 xb +7 xg of the metal branch 3133 are 0.5mm and 7.5mm, respectively. And the size of the metal branch 3133 of each reflection unit 3 is independent of the reflection phase value of the reflection unit 3, i.e. the size of the metal branch 3133 in each reflection unit 3 is the same.
Example 2
The present embodiment has the same structure as embodiment 1, and only the following parameters are adjusted: the beam width of the feed source 1 is 35 °, the distance f from the phase center of the feed source 1 to the reflective front surface 2 is 188.0mm, the widths of the three metal patches of the upper metal branch 3131 and the widths b of the five metal patches of the lower metal branch 3132 are 0.7mm, the pitch of the three metal patches of the upper metal branch 3131, the pitch of the five metal patches of the lower metal branch 3132, and the pitch g of the upper metal branch 3131 and the lower metal branch 3132 are 0.7mm, the width b and the height 8 × b +7 × g of the metal branch 3133 are 0.7mm and 10.5mm, the heights h of the first dielectric substrate 311, the second dielectric substrate 312, the third dielectric substrate 321, and the fourth dielectric substrate 322 are 11.2mm, and the heights h of the first upper rectangular through groove 3111, the second upper through groove 3121, the first lower rectangular through groove 3211, and the first lower rectangular through groove 3221 are 5.6 mm.
The reflection phase of each reflection unit is determined according to the formula<1>And (4) calculating. Obtaining the lengths L of the upper metal branches of the four metal surfaces of each reflection unit i through simulationiAnd its reflection phase phiiThe relationship of (a) is shown by the dashed line in fig. 5.
Example 3
The present embodiment has the same structure and parameters as those of embodiment 1, and only a metal plate with dimensions of 238mm × 238mm is added below the reflection front 2 of embodiment 1, and the metal plate is closely attached to the reflection front 2.
Example 4
The present embodiment has the same structure as embodiment 1, and only the following parameters are adjusted: wherein:
the beam width of the feed source 1 is 30 °, the distance f from the phase center of the feed source 1 to the reflective front surface 2 is 220.0mm, the widths of the three metal patches of the upper metal branch 3131 and the widths b of the five metal patches of the lower metal branch 3132 are 0.3mm, the pitch of the three metal patches of the upper metal branch 3131, the pitch of the five metal patches of the lower metal branch 3132, and the pitch g between the upper metal branch 3131 and the lower metal branch 3132 are 0.3mm, the width b and the height 8 × b +7 × g of the metal branch 3133 are 0.3mm and 4.5mm, respectively, the height h of the first dielectric substrate 311, the second dielectric substrate 312, the third dielectric substrate 321, and the fourth dielectric substrate 322 is 4.8mm, and the heights h of the first upper rectangular through groove 3111, the second upper rectangular through groove 3121, the first lower rectangular through groove 3211, and the first lower rectangular through groove 3221 are 2.4 mm.
The reflection phase of each reflection unit is determined according to the formula<1>And (4) calculating. Obtaining the lengths L of the upper metal branches of the four metal surfaces of each reflection unit i through simulationiAnd its reflection phase phiiThe relationship of (a) is shown by a chain line in fig. 5.
The effects of the present invention can be further illustrated by the following simulations:
firstly, simulation software:
commercially available Ansoft HFSS 15.0 software.
Secondly, simulating contents:
simulation 1, azimuth at a frequency of 10.0GHz
The results of the simulation of the radiation patterns of the first three embodiments of the present invention when the pitch angle θ is-180 ° to 180 ° are shown in fig. 6, in which the solid line is the radiation pattern of
embodiment 1, and the dotted line is the radiation pattern of embodiment 2The pattern, the dotted line, is the radiation pattern of example 3.
As can be seen from fig. 6, the radiation pattern of example 1 has a maximum gain of 25.2dB and a side lobe of less than-18 dB; the maximum gain of the radiation pattern of the embodiment 2 is 24.3dB, and the side lobe is less than-16 dB; the radiation pattern of example 3 has a maximum gain of 25.6dB and a side lobe of less than-18 dB.
Simulation 2, azimuth at a frequency of 10.0GHz
When the pitch angle θ is-180 ° to 180 °, the radiation patterns of the first three embodiments of the present invention are simulated, and the result is shown in fig. 7, where the solid line is the radiation pattern of
embodiment 1, the dotted line is the radiation pattern of
embodiment 2, and the dot-dash line is the radiation pattern of
embodiment 3.
As can be seen from FIG. 7, the maximum gain of the radiation pattern of the embodiment 1 is 25.2dB, and the side lobe is less than-17 dB; the maximum gain of the radiation pattern of the embodiment 2 is 24.3dB, and the side lobe is less than-15 dB; the radiation pattern of example 3 has a maximum gain of 25.6dB and a side lobe of less than-19 dB.
From the simulation results of fig. 6 and 7, it is shown that the difference in the feed and reflection unit parameters will affect the maximum gain and side lobe of the antenna radiation pattern, and the maximum gain of example 1 is only reduced by 0.4dB compared to example 3 with a metal plate.
Simulation 3, setting azimuth angle in the frequency band range of 8.5GHz to 11.5GHz
When the pitch angle θ is 0 °, the gains of the
embodiments 1 and 3 according to the present invention are simulated, and the results are shown in fig. 8, where the solid line is the result of the simulation of the gain of the
embodiment 1, and the dotted line is the result of the simulation of the gain of the
embodiment 3, and as can be seen from fig. 8, the operating band range in which the maximum gain of the
embodiment 1 is reduced within the range of 1dB is 9.5 to 10.8GHz, the corresponding 1dB operating bandwidth is 12.8%, the operating band range in which the maximum gain of the
embodiment 3 is reduced within the range of 1dB is 9.5 to 11.1GHz, the corresponding 1dB operating bandwidth is 15.5%, and compared with the
embodiment 3 in which the metal plate is provided, the results are shown in fig. 8The 1dB operating bandwidth of example 1 drops by only 2.7%.
Simulation 4, in the frequency band range of 1.0GHz to 22.0GHz, set the azimuth angle
The results of simulation of the radar scattering cross section when the x-polarized wave was perpendicularly incident on each of examples 1 and 3 of the present invention with the pitch angle θ being 0 ° are shown in fig. 9. Wherein, the solid line is the simulation curve of the radar scattering cross section of the
embodiment 1, and the dotted line is the simulation curve of the radar scattering cross section of the
embodiment 3, which can be obtained from fig. 9, and the
embodiment 1 has the effect of reducing the radar scattering cross section compared with the
embodiment 3 within the frequency band range of 1.0 to 9.5GHz and 12.5 to 22.0 GHz.
Simulation 5, in the frequency band range of 1.0GHz to 22.0GHz, set the azimuth angle
The results of simulation of the radar scattering cross section when the x-polarized wave was obliquely incident at 20 ° in examples 1 and 3 of the present invention with a pitch angle θ of-20 ° are shown in fig. 10. Wherein, the solid line is the simulation curve of the radar scattering cross section of the
embodiment 1, and the dotted line is the simulation curve of the radar scattering cross section of the
embodiment 3, as can be obtained from fig. 10, the
embodiment 1 has the effect of reducing the radar scattering cross section compared with the
embodiment 3 within the frequency band range of 1.0 to 9.5GHz and 12.5 to 22.0 GHz.
Simulation 6, in the frequency band range of 1.0GHz to 22.0GHz, set the azimuth angle
The results of simulation of the radar scattering cross section when the x-polarized wave was obliquely incident at 40 ° in examples 1 and 3 of the present invention with a pitch angle θ of-40 ° are shown in fig. 11. Wherein, the solid line is the simulation curve of the radar scattering cross section of the
embodiment 1, and the dotted line is the simulation curve of the radar scattering cross section of the
embodiment 3, as can be obtained from fig. 11, the
embodiment 1 has the effect of reducing the radar scattering cross section compared with the
embodiment 3 within the frequency band range of 1.0 to 9.5GHz and 12.5 to 22.0 GHz.
By combining the simulation results, compared with embodiment 3, embodiment 1 realizes the reduction of the scattering cross section of the broadband and wide-angle-range radar under the conditions of less reduction of the maximum gain and the 1dB working bandwidth.
The foregoing description is only four embodiments of the present invention and is not intended to limit the present invention, and it will be apparent to those skilled in the art that various modifications and variations in form and detail can be made without departing from the principle and structure of the present invention after understanding the present general inventive concept, but the modifications and variations are still within the scope of the appended claims and the protection scope of the present invention.