A reconfigurable metasurface unit and low RCS microstrip antenna

Abstract

The present application belongs to the field of metasurface technology, and relates to a reconfigurable metasurface unit and a low RCS microstrip antenna. The reconfigurable metasurface unit is a planar structure, comprising: a first patch and a second patch; the first patch is a rectangular strip structure, the second patch is a rectangular ring structure, the two ends of the first patch are respectively arranged at the midpoints of two sides of the second patch; the midpoints of the other two sides of the second patch are each provided with a variable resistor; and further comprising: four third patches of rectangular strip structure; wherein one corresponding end of two third patches is respectively connected to the two ends of a variable resistor, and the other corresponding end extends perpendicularly in the direction of the first patch and has a gap with the first patch; one corresponding end of the other two third patches is respectively connected to the two ends of another variable resistor, and the other corresponding end extends perpendicularly in the direction of the first patch and has a gap with the first patch. The present application can achieve dynamic and adjustable RCS reduction.

Description

Technical Field

[0001] The present application relates to the field of metasurface technology, and in particular to a reconfigurable metasurface unit and a low RCS microstrip antenna. Background Art

[0002] With increasing informatization, modern warfare is increasingly seeking unilateral battlefield transparency. To reduce the probability of detection by enemy radar, stealth technology is gaining increasing attention worldwide. Radar cross section (RCS) characterizes the scattering characteristics of radar targets, and its reduction is a crucial consideration in stealth technology. Antennas, as crucial tools for transmitting information, must maximize their survivability in electronic warfare. Therefore, minimizing the scattering of incident electromagnetic waves is crucial, making a low RCS particularly important. However, since antennas transmit and receive electromagnetic waves, their scattering characteristics are unique. Reducing RCS requires maintaining stable performance. Therefore, the primary challenge in designing low-RCS antennas is to avoid negatively impacting the antenna's radiation characteristics, such as changes in operating frequency, reductions in operating bandwidth, and reduced antenna gain.

[0003] Traditional rectangular microstrip patch antennas have high RCS radiation, making them difficult to meet the requirements of stealth technology. However, electromagnetic metamaterials, through flexible manipulation of electromagnetic waves, can achieve functions such as frequency selection, wave absorption, and polarization conversion. Combining them with antennas can reduce the antenna's RCS, thereby achieving effective stealth. Absorbing metamaterials primarily reduce RCS by absorbing and consuming electromagnetic wave energy. Through various structures that resonate well with electromagnetic waves, they reduce electromagnetic energy reflection, allowing the metamaterial absorber to absorb and convert the electromagnetic energy into other forms of energy.

[0004] However, the design of RCS-reducing antennas based on electromagnetic metamaterials still faces some challenges. For example, adding a metamaterial coating to the antenna's dielectric plate may increase the antenna's profile; the limited operating bandwidth of the metamaterial can affect the antenna's RCS reduction effectiveness; the polarization sensitivity of the metamaterial can also make the antenna's RCS reduction unstable; and the RCS reduction is not adjustable. Summary of the Invention

[0005] Based on this, it is necessary to provide a reconfigurable metasurface unit and a low RCS microstrip antenna to address the above technical problems, which can achieve dynamic and adjustable RCS reduction.

[0006] A reconfigurable metasurface unit is a planar structure, comprising:

[0007] A first patch and a second patch;

[0008] The first patch is a rectangular strip structure, the second patch is a rectangular ring structure, and the two ends of the first patch are respectively located at the midpoints of two sides of the second patch;

[0009] Variable resistors are provided at the midpoints of the other two sides of the second patch.

[0010] In one embodiment, the invention further comprises: four third patches in rectangular strip-shaped structures;

[0011] One corresponding end of each of the two third patches is connected to two ends of a variable resistor, and the other corresponding end extends perpendicularly toward the first patch and has a gap with the first patch;

[0012] One corresponding end of the other two third patches is connected to two ends of another variable resistor respectively, and the other corresponding end extends perpendicularly toward the first patch and has a gap with the first patch.

[0013] In one embodiment, the invention further comprises: two parasitic branches each having a rectangular strip structure;

[0014] The length directions of the two parasitic branches are both parallel to the length direction of the first patch, and the two parasitic branches are symmetrically spaced on both sides of the second patch.

[0015] In one embodiment, two ends of the first patch extend beyond the edges of corresponding sides of the second patch.

[0016] A low RCS microstrip antenna comprising: a plurality of reconfigurable metasurface units, a radiation patch, a dielectric layer, and a floor layer;

[0017] The reconfigurable metasurface unit and the radiation patch are both arranged on the upper surface of the dielectric layer, and the floor layer is arranged on the lower surface of the dielectric layer.

[0018] In one embodiment, the radiation patch, the dielectric layer, and the floor layer are all rectangular structures;

[0019] The radiation patch coincides with the center of the dielectric layer, and the sides of the radiation patch are parallel to the sides of the dielectric layer in a one-to-one correspondence.

[0020] In one embodiment, a plurality of reconfigurable metasurface unit arrays form a first unit array and a second unit array in a rectangular ring shape, and the first unit array and the second unit array are spaced and arranged around the radiation patch;

[0021] All reconfigurable metasurface units are centrosymmetric about the center of the radiation patch, and all reconfigurable metasurface units are axisymmetric about the symmetry axis of the radiation patch.

[0022] In one embodiment, the length direction of each first patch is parallel to the length direction of the radiation patch.

[0023] In one embodiment, the number of reconfigurable metasurface units in the first unit array is equal to the number of reconfigurable metasurface units in the second unit array.

[0024] In one embodiment, the positions of the reconfigurable metasurface units in the first unit array correspond one-to-one to the positions of the reconfigurable metasurface units in the second unit array.

[0025] The reconfigurable metasurface unit and low RCS microstrip antenna are designed with a first patch, a second patch, and a variable resistor. Reconfigurable technology is employed to electrically reconfigure the antenna and metasurface, dynamically adjusting their operating states and functions. This allows for reconfigurable RCS reduction of the antenna, with a stable reduction effect and more flexible response to meet demand. The antenna's RCS reduction is adjustable by utilizing the dynamic adjustment of the reconfigurable metasurface's ability to absorb electromagnetic waves. By varying the value of the resistor loaded on the metasurface's resonant structure, the frequency of the antenna's RCS reduction changes, thereby achieving reconfigurable adjustment of the antenna's RCS reduction frequency and broadening the RCS reduction bandwidth. Furthermore, by employing an actively adjustable operating frequency band, the same metamaterial absorption structure can be used to achieve RCS reduction for microstrip antennas of different frequency bands. This dynamic RCS reduction is adjustable without affecting the normal operation and original radiation characteristics of the microstrip antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of a reconfigurable metasurface unit in one embodiment;

[0027] Figure 2 1 is a diagram showing the dimensions of a reconfigurable metasurface unit in one embodiment;

[0028] Figure 3 is a three-dimensional schematic diagram of a low RCS microstrip antenna according to an embodiment;

[0029] Figure 4 FIG1 is a top view of a low RCS microstrip antenna according to an embodiment;

[0030] Figure 5 A top view of a reference antenna in one embodiment

[0031] Figure 6 A comparison of S-parameter simulation results of a low RCS microstrip antenna and a reference antenna in one embodiment

[0032] Figure 7 A comparison of the E-plane radiation pattern simulation results of a low RCS microstrip antenna and a reference antenna in an embodiment

[0033] Figure 8 A comparison of the H-plane radiation pattern simulation results of a low RCS microstrip antenna and a reference antenna in an embodiment

[0034] Figure 9 1 is a comparison chart of the monostatic RCS simulation results of a low RCS microstrip antenna at different resistance values ​​in one embodiment and the monostatic RCS simulation results of a reference antenna.

[0035] Radiating patch 1, reconfigurable metasurface unit 2, first patch 21, second patch 22, third patch 23, variable resistor 24, parasitic branch 25, dielectric layer 3, floor layer 4, feeding point 5. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in this application without creative work are within the scope of protection of this application.

[0037] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, the terms "first," "second," and so on, used in this application are for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, and so on, unless otherwise specifically defined.

[0039] In this application, unless otherwise specified or limited, the terms "connect," "fix," etc. should be understood in a broad sense. For example, "fix" can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean internal communication between two elements or an interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0040] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0041] This application provides a reconfigurable metasurface unit, such as Figure 1 As shown, in one embodiment, the reconfigurable metasurface unit is a planar structure, including: a first patch 21 and a second patch 22.

[0042] The first patch 21 is a rectangular strip structure, and the second patch 22 is a rectangular ring structure. The two ends of the first patch 21 are respectively located at the midpoints of two sides of the second patch 22. That is, the first patch 21 and the second patch 22 together form a "sun" structure.

[0043] Variable resistors 24 are provided at the midpoints of the other two sides of the second patch 22, so that the resistance value can be changed as required. Optionally, the variable resistors can also be PIN diodes.

[0044] Preferably, both ends of the first patch 21 extend beyond the edges of corresponding sides of the second patch 22 to better meet the impedance matching characteristics.

[0045] It should be noted that the x direction is the width direction and the y direction is the length direction. Only the case of changing the resistance values ​​of all the resistors loaded on the metasurface units at the same time is analyzed.

[0046] The above-mentioned reconfigurable metasurface unit is designed with a first rectangular strip patch, a second rectangular ring patch and a variable resistor, which improves the overall impedance matching of the antenna. Reconfigurable technology is adopted, and the absorption frequency of the reconfigurable metasurface changes, so that the incident electromagnetic waves in a certain frequency band are absorbed, thereby reducing the RCS of the corresponding frequency band. At the same time, the antenna and metasurface are reconfigured through electrical control, and their working state and function are dynamically adjusted, which can achieve reconfigurable RCS reduction of the antenna, and the reduction effect is stable, which can meet the needs more flexibly. The dynamic adjustment of the reconfigurable metasurface to absorb electromagnetic waves is used to achieve adjustable RCS reduction of the antenna. By changing the resistance value of the resistor loaded on the metasurface resonant structure, the frequency of the antenna RCS reduction is changed, thereby achieving reconfigurable adjustment of the antenna RCS reduction frequency and achieving the effect of widening the RCS reduction bandwidth. Moreover, the active adjustable working frequency band is adopted, and the same metamaterial absorption structure can be used to achieve RCS reduction for microstrip antennas of different frequency bands. The RCS reduction is dynamically adjustable without affecting the normal operation and original radiation characteristics of the microstrip antenna.

[0047] In one embodiment, the invention further comprises: four third patches 23 having rectangular strip structures.

[0048] One corresponding end of two third patches 23 is respectively connected to the two ends of a variable resistor 24, and the other corresponding end extends perpendicularly toward the first patch 21 and has a gap with the first patch 21; one corresponding end of the other two third patches 23 is respectively connected to the two ends of another variable resistor 24, and the other corresponding end extends perpendicularly toward the first patch 21 and has a gap with the first patch 21.

[0049] The third patch in this embodiment can change the absorbing frequency of the antenna by changing its length. Specifically, under the premise that it does not contact the first patch, the absorbing frequency will decrease as the length of the third patch increases.

[0050] In one embodiment, the present invention further comprises: two parasitic branches 25 both in a rectangular strip-shaped structure.

[0051] The length directions of the two parasitic branches 25 are both parallel to the length direction of the first patch 21 , and the two parasitic branches 25 are symmetrically spaced on both sides of the second patch 22 .

[0052] The parasitic branches in this embodiment are a further optimization of the metasurface resonant structure. Their length can be equal to the length of the first patch or the length of the second patch. The parasitic branches can achieve a good impedance match between the equivalent impedance of the metasurface and the impedance of free space, thereby achieving a better wave absorption effect.

[0053] The present application also provides a low RCS microstrip antenna, such as Figure 3 As shown, in one embodiment, it includes: multiple reconfigurable metasurface units 2, radiating patches 1, a dielectric layer 3, and a floor layer 4. The reconfigurable metasurface units 2 and radiating patches 1 are printed on the upper surface of the dielectric layer 3 to form a patch layer, and the floor layer 4 is printed on the lower surface of the dielectric layer 3. The reconfigurable metasurface units 2, radiating patches 1, and floor layer 4 are all made of metal, while the dielectric layer 3 is made of non-metal.

[0054] The radiation patch 1, the dielectric layer 3 and the floor layer 4 are all rectangular structures.

[0055] The center of the radiating patch 1 coincides with the center of the dielectric layer 3, and the edges of the radiating patch 1 are parallel to the edges of the dielectric layer 3 in a one-to-one correspondence. In other words, the four edges of the radiating patch 1 correspond to the four edges of the dielectric layer 3 in a one-to-one correspondence, and the edges of the radiating patch 1 are parallel to the corresponding edges of the dielectric layer 3. Because the shape of the radiating patch 1 is not square, that is, the length and width of the radiating patch 1 are not equal, and the position of the feeding point 5 is not on the symmetry axis (located on the floor layer 4), the antenna has four resonant frequencies, which expands the antenna's operating bandwidth. Of course, other feeding methods in the prior art can also be used.

[0056] Multiple reconfigurable metasurface unit arrays form a first unit array and a second unit array in a rectangular ring shape. The first unit array and the second unit array are spaced apart and arranged around the radiating patch. That is, the first unit array is spaced apart in a rectangular ring shape outside the second unit array, and the second unit array is spaced apart in a rectangular ring shape outside the radiating patch. That is, multiple reconfigurable metasurface units surround the outside of the radiating patch in a "U" shape; all reconfigurable metasurface units are centrosymmetric about the center of the radiating patch, and all reconfigurable metasurface units are axisymmetric about the symmetry axis of the radiating patch. There is no limit on the specific number of reconfigurable metasurface units.

[0057] It should be noted that the feeding mode of the antenna in this embodiment is coaxial feeding.

[0058] The working process of this embodiment is: electromagnetic waves are irradiated onto the metasurface unit, the resistance value of the variable resistor is adjusted, and the absorption frequency of the electromagnetic waves is changed.

[0059] This low-RCS microstrip antenna addresses the issues of strong in-band RCS radiation and narrow operating bandwidth of conventional microstrip antennas after metasurface loading. By utilizing a coplanar structure with the metasurface unit and radiating patch, ultra-wideband RCS reduction is achieved without increasing the existing antenna's profile. Within a resistance adjustment range of 0-500Ω, the frequency range where RCS reduction exceeds 5dB is 4.6-5.65GHz, with a maximum reduction of 12.57dB. This indirectly broadens the antenna's RCS reduction bandwidth without compromising the antenna's radiation performance.

[0060] Preferably, the length direction of each first patch 21 is parallel to the length direction of the radiation patch 1, and the number of reconfigurable metasurface units in the first unit array is equal to the number of reconfigurable metasurface units in the second unit array, so that the adjustment range of RCS corresponds to the adjustment range of the metasurface.

[0061] Further preferably, the positions of the reconfigurable metasurface units in the first unit array correspond one-to-one to the positions of the reconfigurable metasurface units in the second unit array. For example, the eight reconfigurable metasurface units in the first unit array are respectively arranged at the four corners and the midpoints of the sides of the rectangular ring, and the eight reconfigurable metasurface units in the second unit array are also respectively arranged at the four corners and the midpoints of the sides of the rectangle, so as to further make the adjustment range of RCS correspond to the adjustment range of the metasurface, thereby improving the RCS reduction effect and stabilizing the RCS reduction.

[0062] In a specific embodiment, the width direction of the first patch is the x direction, the length direction of the first patch is the y direction, the center coordinate of the radiation patch is (0, 0), and the coordinate of the feeding point is (2.6, 3).

[0063] The size of the radiation patch is 18mm wide × 12.2mm long, the relative dielectric constant of the dielectric layer is 4.4, and the size parameters are 130.5mm wide × 112.5mm long × 2mm thick. The size of the floor layer is 130.5mm wide × 112.5mm long.

[0064] The length lgnd of the reconfigurable metasurface unit is 12.5mm, the width wgnd is 14.5mm, the width w of the second patch is 12mm, the width s1 of the first patch is 0.9mm, the length l of the third patch is 4.5mm, the spacing g between two adjacent third branches is 0.5mm, and the width s2 of the parasitic branch is 0.1mm.

[0065] The number of reconfigurable metasurface units in the first and second unit arrays is 8. The spacing between the reconfigurable metasurface units in the first unit array in both the x and y directions is 3 times the unit size, while the spacing between the reconfigurable metasurface units in the second unit array in both the x and y directions is 1 time the unit size. The spacing between the first and second unit arrays in both the x and y directions is 1 time the unit size, meaning that the spacing between the reconfigurable metasurface units in the first unit array is 3 times the spacing between the reconfigurable metasurface units in the second unit array. Specifically, the spacing between each unit in the first unit array is 3 times the unit size, meaning the spacing in the x direction is 58 mm and the spacing in the y direction is 50 mm. The spacing between each unit in the second unit array is 1 time the unit size, meaning the spacing in the x direction is 29 mm and the spacing in the y direction is 25 mm. The gap between the first and second unit arrays is 1 time the unit size, meaning the spacing between units belonging to different unit arrays in the x direction is 29 mm and the spacing between units belonging to different unit arrays in the y direction is 25 mm.

[0066] Each reconfigurable metasurface unit in the first unit array has a parasitic branch whose edge coincides with the edge of the dielectric layer, that is, the reconfigurable metasurface units in the first unit array are arranged along the edge of the dielectric layer.

[0067] The above embodiment was simulated using finite element simulation software HFSS.

[0068] like Figure 5 The reference antenna shown has dimensional parameters that are exactly the same as those of the embodiment of the present invention. The difference is that the metal patch layer only has an antenna radiation patch and no reconfigurable metasurface unit. The relative dielectric constant of the dielectric layer is 4.4, the size is 130.5mm×112.5mm×2mm, and the size of the radiation patch is 18mm×12.2mm.

[0069] Simulation 1, such as Figure 6As shown, first, the S parameters of the reference antenna are simulated and calculated using HFSS software to obtain the S11 curve. The reference antenna has four operating frequency points, and the frequency bands below -10dB are 3.76-3.88GHz, 5.09-5.37GHz, 6.70-6.84GHz, and 7.26-7.58GHz, respectively. Then, the S parameters of the low RCS antenna of the embodiment of the present invention are simulated and calculated using HFSS software to obtain the S11 curve. Compared with the reference antenna, the S11 curves of the embodiment of the present invention are basically consistent.

[0070] Simulation 2, such as Figure 7 As shown in FIG, HFSS software is used to simulate and calculate the E-plane radiation pattern of the embodiment of the present invention and the reference antenna. Figure 7 It can be seen that, compared with the reference antenna, the E-plane radiation pattern of the embodiment of the present invention has a similar shape, and the gain in the main radiation direction is reduced by 0.6 dB, which has a relatively small impact.

[0071] Simulation 3, such as Figure 8 As shown in FIG, the H-plane radiation pattern of the embodiment of the present invention and the reference antenna is simulated and calculated using HFSS software. Figure 8 It can be seen that, compared with the reference antenna, the H-plane radiation pattern of the embodiment of the present invention has a similar shape, and the gain in the main radiation direction is reduced by 0.6 dB, which has a relatively small impact.

[0072] Simulation 4, such as Figure 9 As shown, the single-station RCS of the reference antenna is first simulated and calculated using HFSS software, and then the single-station RCS of the embodiment of the present invention under different resistance values ​​is simulated and calculated using HFSS software. Figure 9 It can be seen that increasing the resistance value from 0 ohm to 500 ohm shifts the RCS reduction frequency from 4.6 GHz to 5.65 GHz, with a maximum RCS reduction of 12.57 dB. By adjusting the resistance value of the resistor, the embodiment of the present invention achieves an RCS reduction of at least 5 dB within the 4.6-5.65 GHz range. Figure 9 Only five representative resistance values ​​are selected.

[0073] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A reconfigurable metasurface unit, characterized in that: The reconfigurable metasurface unit is a planar structure, comprising: a first patch and a second patch; The first patch is a rectangular strip structure, the second patch is a rectangular ring structure, and the two ends of the first patch are respectively arranged at the midpoints of two opposite sides of the second patch; Variable resistors are provided at the midpoints of the other two opposite sides of the second patch.

2. The reconfigurable metasurface unit according to claim 1, characterized in that Also includes: A third patch of four rectangular strip structures; One corresponding end of each of the two third patches is connected to two ends of a variable resistor, and the other corresponding end extends perpendicularly toward the first patch and has a gap with the first patch; One corresponding end of the other two third patches is connected to two ends of another variable resistor respectively, and the other corresponding end extends perpendicularly toward the first patch and has a gap with the first patch.

3. The reconfigurable metasurface unit according to claim 1 or 2, characterized in that: Also includes: Two parasitic branches, both of which are rectangular strip-like structures; The length directions of the two parasitic branches are both parallel to the length direction of the first patch, and the two parasitic branches are symmetrically spaced on both sides of the second patch.

4. The reconfigurable metasurface unit according to claim 1 or 2, characterized in that: Two ends of the first patch respectively extend beyond the edges of corresponding sides of the second patch.

5. A low RCS microstrip antenna, characterized in that: include: A plurality of reconfigurable metasurface units, radiation patches, dielectric layers, and floor layers according to any one of claims 1 to 4; The reconfigurable metasurface unit and the radiation patch are both arranged on the upper surface of the dielectric layer, and the floor layer is arranged on the lower surface of the dielectric layer.

6. The low RCS microstrip antenna according to claim 5, characterized in that: The radiation patch, the dielectric layer and the floor layer all have rectangular structures; The radiation patch coincides with the center of the dielectric layer, and the sides of the radiation patch are parallel to the sides of the dielectric layer in a one-to-one correspondence.

7. The low RCS microstrip antenna according to claim 6, characterized in that: A plurality of reconfigurable metasurface unit arrays form a first unit array and a second unit array in a rectangular ring shape, wherein the first unit array and the second unit array are spaced apart and arranged around the radiation patch; All reconfigurable metasurface units are centrosymmetric about the center of the radiation patch, and all reconfigurable metasurface units are axisymmetric about the symmetry axis of the radiation patch.

8. The low RCS microstrip antenna according to claim 7, characterized in that: The length direction of each first patch is parallel to the length direction of the radiation patch.

9. The low RCS microstrip antenna according to claim 8, characterized in that: The number of reconfigurable metasurface units in the first unit array is equal to the number of reconfigurable metasurface units in the second unit array.

10. The low RCS microstrip antenna according to claim 9, characterized in that: The positions of the reconfigurable metasurface units in the first unit array correspond one-to-one to the positions of the reconfigurable metasurface units in the second unit array.

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