Ultra-wideband stealth antenna with loaded frequency-tiled surface

Abstract

This invention discloses an ultra-wideband stealth antenna with a frequency-spliced ​​surface, comprising: five dielectric substrates arranged sequentially from top to bottom; a PCM layer printed on the upper surface of the first dielectric substrate; the PCM layer employing a polarization-conversion metal patch; an absorbing layer printed on the upper surface of the second dielectric substrate, the absorbing layer employing a multi-resonant metal structure; a third dielectric substrate composed of two dielectric substrates stacked vertically, with a three-layer metal structure having a transparent layer disposed on the upper, between, and lower parts of the two dielectric substrates respectively; the absorbing layer and the transparent layer constitute an ATFSS layer, the ATFSS layer realizing a frequency response of absorption-transmission-absorption; an in-band absorbing layer printed on the upper surface of the fourth dielectric substrate, the in-band absorbing layer employing a metal square ring with a concave structure on each side; and a radiating structure printed on the upper surface of the fifth dielectric substrate, with a metal base plate disposed on the lower surface and coaxial back-feeding. This invention can widen the antenna's RCS and reduce bandwidth, achieving good low-scattering characteristics in various complex electromagnetic environments.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology, specifically relating to an ultra-wideband stealth antenna with a frequency splicing surface, which can be used to reduce the radar cross section of antennas on airborne platforms. Background Technology

[0002] In today's complex and ever-changing military environment, stealth technology remains a crucial element of military operations. Radar cross section (RCS) is an important parameter for evaluating a target's reflection characteristics of incident electromagnetic waves from radar, and a key factor determining the stealth performance of a friendly target. The lower the RCS of a target, the weaker its scattering of incident electromagnetic waves, making it less likely to be detected by enemy radar, and thus exhibiting better stealth performance. According to radar equations, if the radar cross section (RCS) of an airborne platform can be reduced to below 10 dB, the detection range of the airborne platform by a detection radar will be reduced by 50%. Antennas are an indispensable part of wireless communication systems. Meanwhile, antennas need to transmit and receive electromagnetic waves. Traditional methods for reducing RCS, such as reshaping or applying absorbing materials, cannot be used at the antenna installation location, as this would greatly affect the radiation performance of the array antenna. In addition, although low RCS antennas based on circuit analog absorbers can reduce the RCS of bistatic antennas, they will significantly affect the radiation performance of the array antenna. Frequency selective surfaces (FSS) only reduce the single-station RCS of the antenna outside the operating frequency band, and their ability to reduce the RCS of the antenna within the operating frequency band and bistatic antennas is very limited, making them unable to cope with rapidly developing radar detection technologies. Summary of the Invention

[0003] The purpose of this invention is to provide an ultra-wideband stealth antenna with a frequency-spliced ​​surface, so as to ensure normal antenna radiation while widening the antenna's RCS and reducing the bandwidth, thereby achieving good low-scattering characteristics in various complex electromagnetic environments.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] An ultra-wideband stealth antenna with a frequency-spliced ​​surface includes: a first dielectric substrate, a second dielectric substrate, a third dielectric substrate, a fourth dielectric substrate, and a fifth dielectric substrate arranged sequentially from top to bottom; wherein:

[0006] A PCM layer is printed on the upper surface of the first dielectric substrate; the PCM layer adopts a polarization conversion metal patch, which includes a metal strip and a symmetrical double fork arm structure loaded on both sides of the metal strip;

[0007] An absorbing layer is printed on the upper surface of the second dielectric substrate, and the absorbing layer adopts a multi-resonant metal structure.

[0008] The third dielectric substrate is made of two dielectric substrates stacked one on top of the other, and a three-layer metal structure with a wave-transmitting layer set on the top, between and at the bottom of the two dielectric substrates respectively; the wave-absorbing layer and the wave-transmitting layer constitute the ATFSS layer, and the ATFSS layer realizes the frequency response of wave absorption-wave transmission-wave absorption;

[0009] The upper surface of the fourth dielectric substrate is printed with an inner absorbing layer, which is a metal square ring with a concave structure on each side.

[0010] The upper surface of the fifth dielectric substrate is printed with a radiating structure, and the lower surface is provided with a metal base plate and uses coaxial back-to-back power supply.

[0011] The first dielectric substrate, the second dielectric substrate, the third dielectric substrate, the fourth dielectric substrate, and the fifth dielectric substrate are all separated by air layers.

[0012] Furthermore, the PCM layer is composed of periodically arranged square PCM units, each containing the polarization conversion metal patch; wherein, the metal strip is inclined at 45° relative to the edge of the PCM unit, and the double fork structure includes a set of fork arms spaced apart and symmetrically arranged on the metal strip; each set of fork arms includes two arms of different lengths, which are arranged on both sides of the metal strip and perpendicular to each other, forming a harpoon-like structure together with the metal strip.

[0013] Furthermore, the absorbing layer includes periodically arranged absorbing units, and the multi-resonant metal structure includes a square ring arranged within the absorbing units. At the four vertices of the square ring, a rectangular metal ring with a bent strip is connected by a metal strip to each of the four vertices. The four first lumped resistors are respectively loaded at the center of each side of the square ring. The rectangular metal ring is connected to the metal strip at the middle of its front short side. The bent strip inside the rectangular metal ring starts from the middle of its rear short side, first extending forward for a length L5, then downward for a length L6, then forward for a length L7, then upward for a length L8, then forward for a length L9, then downward for a length L10, then forward for a length L11, and finally extending upward and downward for a total length L12. L8>L6, L8>L10, and L5 and L11 are on a straight line.

[0014] Furthermore, in the three-layer metal structure of the wave-transparent layer, the first and third layers are metal rings, and the second layer is a metal plate with a circular metal disc cut out from the middle.

[0015] Furthermore, the metal rings and the circular holes formed after the metal discs are removed from the three-layer metal structure are arranged coaxially.

[0016] Furthermore, a second lumped resistor is loaded into the concave structure of the fourth dielectric plate.

[0017] Furthermore, the radiating structure includes periodically arranged radiating elements, each containing a microstrip antenna.

[0018] A wireless communication system, wherein the system is equipped with an ultra-wideband stealth antenna on the frequency splicing surface.

[0019] An aerial platform equipped with the aforementioned wireless communication system.

[0020] Compared with the prior art, the present invention has the following technical features:

[0021] 1. The present invention employs a spliced ​​metasurface with electromagnetic wave hybrid effect, which is composed of a transmission-reflection integrated PCM and an ATFSS, and has a frequency response of absorption-transmission-absorption-scattering.

[0022] 2. The integrated transmission-reflection PCM designed in this invention can achieve low insertion loss transmission within the operating frequency band of ATFSS without affecting the operating characteristics of ATFSS. Outside the operating frequency band of ATFSS, it has polarization conversion characteristics, which can convert the main polarized wave into a cross-polarized wave. It can further widen the RCS of the antenna and reduce the bandwidth based on ATFSS.

[0023] 3. The absorbing layer of the present invention adopts a bent structure, thereby realizing the miniaturization of the absorbing layer.

[0024] 4. The in-band absorbing layer of the present invention can absorb incident electromagnetic waves within the operating frequency band, thereby achieving low in-band RCS characteristics of the antenna.

[0025] 5. All metal structures in this invention are centrosymmetric and have polarization insensitivity, making them suitable for various complex electromagnetic environments. Attached Figure Description

[0026] Figure 1 This is an overall structural diagram of the ultra-wideband stealth antenna provided by the present invention;

[0027] Figure 2 This is a schematic diagram of the PCM layer unit structure of the antenna of the present invention;

[0028] Figure 3 (a) and (b) are schematic diagrams of the overall and partial structure of the absorbing layer of the antenna of the present invention;

[0029] Figure 4 This is a schematic diagram of the bandpass FSS unit structure of the antenna of the present invention;

[0030] Figure 5 This is a schematic diagram of the in-band absorbing layer structure of the antenna of the present invention;

[0031] Figure 6 This is a schematic diagram of the radiating structure of the antenna of the present invention;

[0032] Figure 7 The S of the antenna and reference antenna of the present invention 11 Comparison chart of reflection coefficient amplitude;

[0033] Figure 8 (a) and (b) are comparison diagrams of the radiation patterns of the antenna of the present invention and the reference antenna at 8.7 GHz in the E-plane and H-plane.

[0034] Figure 9 (a) and (b) are comparison diagrams of the radar cross section (RCS) of the antenna designed in this invention and the reference antenna, where (a) is the case of x-polarized incident wave and (b) is the case of y-polarized incident wave. Detailed Implementation

[0035] The frequency splicing surface is based on the absorptive / transmissive frequency selective surface (ATFSS) and combined with the transmission-reflection integrated polarization conversion metasurface (PCM). It is loaded above the in-band low RCS antenna to form an ultra-wideband stealth antenna system. It can reduce the in-band / out-of-band and mono-site / dual-site RCS of the antenna without affecting the antenna radiation characteristics.

[0036] Reference Figure 1 This invention provides an ultra-wideband stealth antenna with a frequency-stitched metasurface. It combines an ATFSS (Advanced Transmitter-Frequency Synchronous Surface) with a transmission-reflection integrated PCM to achieve the characteristics of an integrated radiation and scattering antenna system. By loading the invented frequency-stitched metasurface structure above a low-RCS antenna within its band, it achieves low scattering characteristics (RCS reduction bandwidth of 2GHz~23GHz) over an ultra-wideband range while ensuring normal antenna radiation. The stealth antenna of this invention includes, from top to bottom, a first dielectric substrate 1, a second dielectric substrate 2, a third dielectric substrate 3, a fourth dielectric substrate 4, and a fifth dielectric substrate 5; wherein:

[0037] A PCM layer 6 is printed on the upper surface of the first dielectric substrate 1; the PCM layer 6 employs a polarization conversion metal patch; the polarization conversion metal patch includes a 45° inclined surface. o The metal strip 62 has symmetrical double fork structure 63 loaded on both sides; the PCM layer 6 converts the main polarization wave outside the ATFSS operating frequency band into a cross-polarization wave through good polarization conversion characteristics, thereby further widening the RCS and reducing the bandwidth on the basis of ATFSS. Within the ATFSS operating frequency band, the insertion loss of the PCM layer is less than -1.5dB, so it does not affect the working performance of ATFSS.

[0038] Reference Figure 2 In this invention, the PCM layer 6 is composed of periodically arranged square PCM units 61, each containing a polarization conversion metal patch. The metal strip 62 is inclined at 45° relative to the edge of the PCM unit 61; for example, the metal strip 62 can be arranged on the diagonal of the PCM unit 61. The double-fork structure 63 includes a set of fork arms spaced apart and symmetrically arranged on the metal strip 62. Each set of fork arms includes two arms 631 of different lengths, which are arranged on both sides of the metal strip 62 and perpendicular to each other, forming a harpoon-like structure together with the metal strip 62. In one embodiment of this invention, the periodicity of the PCM unit... P The length of the metal strip in the PCM unit is 62 mm, which is 7 mm. L 1 is 6.6mm wide W 1 is 0.3mm; one of the support arms in each fork arm is 631mm long. L 2 is 1mm, and the length of the other support arm is 631. L 3 is 0.7mm; the width of the two support arms W Both are 0.3mm.

[0039] The second dielectric substrate 2 has an absorbing layer 7 printed on its upper surface. The absorbing layer 7 adopts a multi-resonant metal structure, which has multiple absorbing resonant points in a wide bandwidth, thereby broadening the absorbing bandwidth.

[0040] Reference Figure 3 The absorbing layer 7 in this invention includes periodically arranged absorbing units. The multi-resonant metal structure includes a square ring 71 arranged within the absorbing units. At each of the four vertices of the square ring 71, a rectangular metal ring 73 with a bent strip 75 and the same structure is connected by a metal strip 72. Four first lumped resistors 74 with a resistance of 120 ohms are respectively loaded at the center of each side of the square ring 71. Figure 3 In the example, the length direction of the rectangular metal ring 73 is defined as the front-to-back direction, and the width direction is defined as the up-to-down direction. The rectangular metal ring 73 is connected to the metal strip 72 at the middle of its short side at the front. The bent strip 75 inside the rectangular metal ring 73 starts from the middle of its short side at the rear, first extending forward for a length L5, then downward for a length L6, then forward for a length L7, then upward for a length L8, then forward for a length L9, then downward for a length L10, then forward for a length L11, and finally extending upward and downward for a total length L12. Among these, L8>L6, L8>L10, and L5 and L11 are on a straight line.

[0041] In one embodiment of the present invention, see Figure 3The absorption unit has a period of 12mm. The inner length L1 of the square ring 71 is 1.8mm, and the width W1 of each side is 0.3mm. The length L2 of each first lumped resistor 74 is approximately 0.5mm, and the width is W1. The length L3 of the metal strip between the square ring 71 and the rectangular metal ring 74 is 0.85mm. The outer length L4 of the long side of the rectangular metal ring 74 is 3.2mm, the outer length W2 of the short side of the rectangular metal ring 74 is 2.6mm, and the thickness W3 of the long and short sides is 0.2mm. The width of the bent strip 75 inside the rectangular metal ring 73 is W3, and the lengths L5, L6, L7, L8, L9, L10, L11, and L12 are 1.6mm.

[0042] The third dielectric substrate 3 is made by stacking two dielectric substrates on top and bottom. A three-layer metal structure with a wave-transmitting layer 8 is set on the top, between and at the bottom of the two dielectric substrates respectively. The first and third layers of the three-layer metal structure are metal rings 81, and the second layer is a metal plate 82. A circular metal disc is cut out in the middle of the metal plate 82. The absorbing layer 7 and the wave-transmitting layer 8 constitute the ATFSS layer. The ATFSS layer realizes the frequency response of absorbing-transmitting-absorbing.

[0043] Reference Figure 4 The wave-transparent layer 8 in this invention includes periodically arranged wave-transparent units, with a three-layer metal structure disposed at the center of the wave-transparent units; the metal rings 81 and the circular holes formed after the metal discs are removed from the three-layer metal structure are arranged coaxially. In one embodiment of this invention, the period of the wave-transparent units is 12mm, the inner diameter d1 of the metal rings in the first and third layers is 6mm, and the difference between the inner and outer diameters is 2.4mm; the diameter d3 of the circular metal discs removed from the center of the metal plate is 5.6mm.

[0044] An in-band absorbing layer 9 is printed on the upper surface of the fourth dielectric substrate 4. The in-band absorbing layer 9 adopts a metal square ring 91 with a concave structure 93 on each side, and a second lumped resistor 92 with a strength of 120 ohms is loaded in the concave structure. The in-band absorbing layer 9 can absorb electromagnetic waves in the operating frequency band and reduce the in-band RCS of the antenna.

[0045] Reference Figure 5 The in-band absorbing layer 9 of this invention includes periodically arranged in-band absorbing units, and a metal square ring 91 with a concave structure 93 is disposed within the in-band absorbing unit; in one embodiment of this invention, the periodicity of the absorbing unit... P The outer side length of the metal square ring is 8mm. L 1 is 6mm, and the height of the concave structure on each side is 93. L 2 is 0.7mm, the length of the concave structure L3 is 1.8mm, the width of the second lumped resistor is 92. W 1 is 0.6mm.

[0046] The upper surface of the fifth dielectric substrate 5 is printed with a radiating structure 10, and the lower surface is provided with a metal base plate 11 and is fed by a coaxial back-to-back current.

[0047] Reference Figure 6 The radiating structure 10 of the present invention includes periodically arranged radiating elements, each containing a microstrip antenna; the length of the radiating element and the metal base plate... L The length of the microstrip antenna is 84mm, the length M is 10.4mm, the distance N between the feed point of the microstrip antenna and its top edge is 3.4mm, and it adopts back-to-back coaxial feeding.

[0048] The first dielectric substrate 1, the second dielectric substrate 2, the third dielectric substrate 3, the fourth dielectric substrate 4, and the fifth dielectric substrate 5 are all separated by air layers. In one embodiment of the present invention, the first dielectric substrate 1 is made of FR4 material with a relative permittivity of 4.4 and a thickness of 0.2 mm; the second dielectric substrate 2 is made of F4B material with a relative permittivity of 3.5 and a thickness of 0.6 mm; the third dielectric substrate 3 all have a relative permittivity of 2.65 and a thickness of 0.8 mm; the fourth dielectric substrate 4 is made of F4B material with a relative permittivity of 2.2 and a thickness of 1.3 mm; and the fifth dielectric substrate 5 has a relative permittivity of 2.2 and a thickness of 1 mm.

[0049] Air layer height between the second dielectric plate 2 and the first dielectric plate 1 h 1 is 4.8mm, the air layer height between the third dielectric plate 3 and the second dielectric plate 2. h 2 is 6mm, the air gap height between the fourth dielectric plate 4 and the third dielectric plate 3. h 3 is 19mm, the air layer height between the fourth dielectric plate 4 and the fifth dielectric plate 5. h 4 represents 1 mm.

[0050] The technical effects of this invention can be further illustrated by the following simulation experiments.

[0051] 1. Simulation conditions

[0052] The antenna of the invention described above was simulated using the commercial simulation software CST Studio Suite 2023.

[0053] 2. Simulation Content

[0054] Simulation 1: The backlash loss of the reference antenna and the invented antenna was simulated and calculated using the commercial simulation software CST Studio Suite 2023. The results are as follows: Figure 7 As shown. From Figure 7It can be seen that the impedance bandwidth of the invented antenna at -10dB is 8.77-8.82GHz, while that of the reference antenna at -10dB is 8.75-8.85GHz. Therefore, it can be seen that the impedance bandwidth of the invented antenna at -10dB is almost unchanged compared with that of the reference antenna.

[0055] Simulation 2: The E-plane and H-plane radiation patterns of the reference antenna and the invented antenna were simulated and calculated using the commercial simulation software CST Studio Suite 2023. The results are as follows: Figure 8 As shown. From Figure 8 As can be seen, compared with the unloaded frequency-stitched metasurface, the radiation gain of the low RCS antenna with the frequency-stitched surface remains almost unchanged, but the direction of maximum radiation changes. This indicates that the antenna of this invention has good radiation performance.

[0056] Simulation 3: Using the commercial simulation software CST Studio Suite 2023, the monostatic radar cross sections of the reference antenna and the invented antenna under two different polarizations of incident wave illumination were simulated and calculated. The results are as follows: Figure 9 As shown. From Figure 9 As can be seen, compared with the reference antenna, the antenna of this invention can achieve in-band / out-of-band monocentric RCS reduction in the range of 2GHz to 23GHz. Under x-polarization and y-polarization, the maximum reduction in monocentric RCS at 17GHz is 35dB.

[0057] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An ultra-wideband stealth antenna with a frequency-spliced ​​surface, characterized in that, include: The first dielectric substrate (1), the second dielectric substrate (2), the third dielectric substrate (3), the fourth dielectric substrate (4), and the fifth dielectric substrate (5) are arranged sequentially from top to bottom; wherein: A PCM layer (6) is printed on the upper surface of the first dielectric substrate (1); the PCM layer (6) adopts a polarization conversion metal patch, which includes a metal strip (62) and a symmetrical double fork arm structure (63) loaded on both sides of the metal strip (62); The upper surface of the second dielectric substrate (2) is printed with an absorbing layer (7), which adopts a multi-resonant metal structure. The third dielectric plate (3) is made by stacking two dielectric plates on top and bottom, and a three-layer metal structure of a wave-transmitting layer (8) is set on the upper part, between and below the two dielectric plates respectively; the wave-absorbing layer (7) and the wave-transmitting layer (8) constitute the ATFSS layer, and the ATFSS layer realizes the frequency response of wave absorption-wave transmission-wave absorption. An inner absorbing layer (9) is printed on the upper surface of the fourth dielectric substrate (4). The inner absorbing layer (9) adopts a metal square ring (91) with a concave structure (93) on each side. A second lumped resistor (92) is loaded in the concave structure (93) of the fourth dielectric substrate (4). The upper surface of the fifth dielectric substrate (5) is printed with a radiating structure (10), and the lower surface is provided with a metal base plate (11) and is fed back along a coaxial line. The first dielectric plate (1), the second dielectric plate (2), the third dielectric plate (3), the fourth dielectric plate (4), and the fifth dielectric plate (5) are all separated by air layers; The PCM layer (6) is composed of periodically arranged square PCM units (61), and the PCM unit contains the polarization conversion metal patch; wherein, the metal strip (62) is inclined at 45° relative to the edge of the PCM unit (61), and the double fork structure (63) includes a set of fork arms spaced apart and symmetrically arranged on the metal strip (62); each set of fork arms includes two support arms (631) of different lengths, the two support arms (631) are arranged on both sides of the metal strip (62) and perpendicular to each other, together with the metal strip (62) to form a harpoon-shaped structure.

2. The ultra-wideband cloaked antenna loading frequency-tiled surfaces of claim 1, wherein, The absorbing layer (7) includes periodically arranged absorbing units. The multi-resonant metal structure includes a square ring (71) arranged inside the absorbing unit. At the four vertices of the square ring (71), a rectangular metal ring (73) with the same structure and a bent strip (75) is connected by a metal strip (72). The four first lumped resistors (74) are respectively loaded at the center of each side of the square ring (71). The rectangular metal ring (73) is connected to the metal strip (72) at the middle of the short side in front. The bent strip (75) inside the rectangular metal ring (73) starts from the middle of the short side in the rear, first extending forward for a length L5, then downward for a length L6, then forward for a length L7, then upward for a length L8, then forward for a length L9, then downward for a length L10, then forward for a length L11, and finally extending upward and downward for a total length L12. L8 > L6, L8 > L10, and L5 and L11 are on a straight line.

3. The ultra-wideband cloaked antenna loading frequency-tiled surfaces of claim 1, wherein, In the three-layer metal structure of the wave-transparent layer (8), the first and third layers are metal rings (81), and the second layer is a metal plate (82), in which a circular metal disc is cut out.

4. The ultra-wideband cloaked antenna loading frequency-tiled surfaces of claim 1, wherein, The metal ring (81) in the three-layer metal structure and the circular hole formed after the metal disc is removed are arranged coaxially.

5. The ultra-wideband cloaked antenna loading frequency-tiled surfaces of claim 1, wherein, The radiating structure (10) includes periodically arranged radiating elements, in which microstrip antennas are arranged.

6. A wireless communication system, characterized by The system is equipped with an ultra-wideband stealth antenna with a frequency-splicing surface as described in any one of claims 1-5.

7. An aerial platform, characterized by, The platform is equipped with the wireless communication system according to claim 6.

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