An analog reconfigurable transmissive metasurface for beam control in the C-band

Abstract

The present invention discloses an analog reconfigurable transmissive metasurface for beam control in the C-band. The metasurface is composed of a number of sub-wavelength scale metasurface units. The first metal layer (1) and the third metal layer (7) of the metasurface unit structure both include a slotted metal patch (1.1) and a varactor diode (1.2). The second metal layer (3) is composed of a metal plane with a central hole. The feed network layer (5) is composed of 8 feed lines (5.1). Each feed line is connected in series with the varactor diodes on 8 metasurface units. The anode of the varactor diode (1.2) is connected to the second metal layer (3) through the first metallized via (A), and the cathode is connected to the feed network layer (5) through the second metallized via (B). This metasurface has a simple structure and low cost, and can be mass-produced using printed circuit board and chip technology.

Description

Technical Field

[0001] The present invention relates to an analog reconfigurable transmissive metasurface for beam control in the C - band, belonging to the technical field of novel artificial electromagnetic materials. Background Art

[0002] A metasurface is an artificially designed electromagnetic structure formed by periodic or aperiodic extension on a two - dimensional plane at a sub - wavelength scale. Once a traditional metasurface is designed, its structure and electromagnetic characteristics remain fixed. In recent years, with the development of reconfigurable technologies, active circuit devices (such as PIN diodes, varactor diodes, MEMS, etc.) have been introduced into traditional metasurface units. By changing the bias voltage of the circuit devices, the electromagnetic response of the metasurface units can be controlled at will. According to the array theory, by reasonably controlling the electromagnetic response of the metasurface units, the customization of the metasurface functions can be achieved, and then beam control technologies such as multi - beam, beam scanning, flat - top beam, and cosine beam can be realized.

[0003] Phased - array antennas are the mainstream technology for beam control. They achieve the control of the amplitude and phase of electromagnetic waves by using a large number of expensive active devices to construct an extremely complex feeding network, and finally achieve the purpose of beam control. However, due to the integration of a large number of active devices in its feeding network, there are many problems in terms of power consumption, heat dissipation, etc.

[0004] Reconfigurable metasurfaces use spatial feeds and integrate phase - adjustable device technologies. Compared with traditional phased - array antennas, they do not require a complex and expensive feeding network and attract the attention of researchers with the advantages of simple structure and low cost. Currently, a large amount of work focuses on the research of digital metasurfaces. The 1 - bit digital reconfigurable metasurface can provide two discrete phase states with a phase difference of 180° due to the loading of PIN diodes and can be used to complete beam control, but it cannot avoid the error caused by phase quantization. Summary of the Invention

[0005] Technical Problem: In order to overcome the deficiencies of digital metasurfaces, the purpose of the present invention is to provide an analog reconfigurable transmissive metasurface for beam control in the C - band. By integrating two varactor diodes on the metasurface unit, it can achieve an analog reconfiguration of the transmission phase from 0° to 180°. In addition, it has the advantages of simple structure and low cost.

[0006] Technical solution: An analog reconfigurable transmissive metasurface for beam control in the C-band according to the present invention is characterized in that the metasurface is composed of a number of sub-wavelength scale metasurface units; the structures of the metasurface units from top to bottom are a first metal layer, a first dielectric layer, a second metal layer, a prepreg layer, a feeding network layer, a second dielectric layer, and a third metal layer; the first metal layer and the third metal layer both include slotted metal patches and varactor diodes; the second metal layer is composed of a metal plane with a central hole; the feeding network layer is composed of N feed lines, and each feed line is connected in series with the varactor diodes on N metasurface units (for a metasurface with N*N units, N feed lines are required, and each feed line is connected in series with N varactor diodes. For an 8*8 unit metasurface, 8 feed lines are required; for a 10*10 unit metasurface, 10 feed lines are required, and each feed line is connected in series with the varactor diodes on 10 metasurface units), the anode of the varactor diode is connected to the second metal layer through a first metallization via, and the cathode is connected to the feeding network layer through a second metallization via, and N is a natural number.

[0007] The first metal layer and the third metal layer have the same structure, both being a slotted metal patch in the middle, and the anodes and cathodes of the varactor diodes are respectively connected to the metal patches on both sides of the slot.

[0008] A large round hole is opened in the center of the second metal layer, and a small round hole is opened beside the large round hole. The diameter of the small round hole is larger than the diameter of the second metallization via, so that the second metallization via passes through the small round hole without being connected to the second metal layer, and the second metal layer is connected to the anodes of all varactor diodes through the first metallization via.

[0009] The feeding network layer is composed of N feed lines, and each feed line is connected to the cathodes of the varactor diodes of a column of metasurface units through a second metallization via.

[0010] For the first metal layer and the third metal layer, the metal patches are circular, with a diameter of 18 mm, and the width of the slots in the patches is 0.65 mm.

[0011] For the second metal layer, the shape of the central hole is circular, and the diameter of the round hole is 8.5 mm.

[0012] The first dielectric layer, the prepreg layer, and the second dielectric layer all adopt microwave circuit boards.

[0013] The microwave circuit boards adopted by the first dielectric layer and the second dielectric layer have a dielectric constant of 3.48, a loss tangent of 0.0037, and a thickness of 1.524 mm.

[0014] The microwave circuit board adopted by the prepreg layer has a dielectric constant of 3.52, a loss tangent of 0.004, and a thickness of 0.1 mm.

[0015] The varactor diode model is MA46H120, and the capacitance value change range is 0.14 to 1.2 pF.

[0016] Beneficial effects:

[0017] 1. The transmissive analog metasurface is mainly composed of three metal layers and two dielectric layers. The multi-layer stacked structure design enables a larger transmission phase coverage range of the metasurface unit.

[0018] 2. The transmissive analog metasurface can achieve beam control by adjusting the reverse bias voltage of two varactor diodes and reasonably controlling the phase of each metasurface unit.

[0019] 3. The transmissive analog metasurface combines the advantages of a microstrip array antenna with a small volume and a traditional parabolic antenna with a high gain, and has the advantages of easy transportation and installation.

[0020] 4. The transmissive analog metasurface adopts the space feed technology. While using a horn antenna irradiation as the feed, it integrates the phase adjustment device varactor diode. Therefore, there is no need for a complex and expensive feed network composed of numerous phase shifters, couplers, and attenuators. Thus, it has low cost and a simple structure, and there is no need to consider power consumption problems such as heat dissipation.

[0021] 5. The transmissive analog metasurface is composed of microwave circuit boards and patch diodes, and can be produced using mature printed circuit board technology and chip technology. The production difficulty is small, it is easy to process in batches, and the cost is also reduced.

[0022] 6. The transmissive analog metasurface adopts the reconfigurable technology. Without changing its physical structure, it can dynamically regulate the phase of the metasurface unit by controlling the external voltage, so as to customize the characteristics of the metasurface as desired to achieve functions including but not limited to beam deflection, multi-beam, flat-top beam, electromagnetic wave focusing, etc.

[0023] 7. The transmissive analog metasurface does not need to worry about the problem of feed blockage existing in the reflective metasurface, has a high aperture efficiency and a low scattering cross-section, and has important applications in satellites, radars, etc. Description of the drawings

[0024] Figure 1 It is a structural diagram of the metasurface array,

[0025] Figure 2 It is a laminated structure diagram of the metasurface unit,

[0026] Figure 3 It is Figure 1 a perspective view of the metasurface unit in

[0027] Figure 4 For Figure 1 Structural diagrams of the first metal layer and the third metal layer of the metasurface unit

[0028] Figure 5 For Figure 1 Structural diagram of the second metal layer of the metasurface unit

[0029] Figure 6 For Figure 1 Schematic diagram of the equivalent second - order band - pass filter of the metasurface unit

[0030] Figure 7 For Figure 1 Results of the transmission amplitude and phase of the metasurface unit varying with the capacitance value at 5.8 GHz

[0031] Figure 8 For Figure 1 Near - field results of 30° beam control of the metasurface array

[0032] Among them are: the first metal layer 1, the first dielectric layer 2, the second metal layer 3, the prepreg layer 4, the feeding network layer 5, the second dielectric layer 6, and the third metal layer 7; the slotted metal patch 1.1, the varactor diode 1.2, the large round hole 3.1, the small round hole 3.2, the feeder 5.1, the first metallized via A, and the second metallized via B Specific implementation manners

[0033] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention

[0034] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance

[0035] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations

[0036] These and other aspects of the embodiments of the present invention will be apparent from the following description and the accompanying drawings. In these descriptions and drawings, specific embodiments of some of the embodiments of the present invention are specifically disclosed to represent some ways of implementing the principles of the embodiments of the present invention, but it should be understood that the scope of the embodiments of the present invention is not limited thereto. On the contrary, the embodiments of the present invention include all variations, modifications, and equivalents that fall within the spirit and scope of the appended claims.

[0037] The present invention will be described below with reference to the accompanying drawings.

[0038] An embodiment of the present invention provides a reconfigurable transmissive analog metasurface for beam control in the C band. As Figure 1 shown, the metasurface is composed of 8×8 cells, and the varactor diodes in a column of cells along the y direction are serially connected together by a feeder.

[0039] In an embodiment of the present invention, as Figure 2 shown, the metasurface is composed of a number of sub-wavelength-scale metasurface cells; the metasurface cell structure from top to bottom is the first metal layer 1, the first dielectric layer 2, the second metal layer 3, the prepreg layer 4, the feeding network layer 5, the second dielectric layer 6, and the third metal layer 7; both the first metal layer 1 and the third metal layer 7 include a slotted metal patch 1.1 and a varactor diode 1.2; the second metal layer 3 is composed of a metal plane with a central hole; the feeding network layer 5 is composed of 8 feeders 5.1, and each feeder serially connects the varactor diodes on 8 metasurface cells. The anode of the varactor diode 1.2 is connected to the second metal layer 3 through the first metallization via A, and the cathode is connected to the feeding network layer 5 through the second metallization via B. The first metal layer 1 and the third metal layer 7 have the same structure, both being a middle-slotted metal patch, and the anodes and cathodes of the varactor diodes are respectively connected to the metal patches on both sides of the slot. The second metal layer 3 has a large round hole 3.1 in the center, and a small round hole 3.2 is opened beside the large round hole. The diameter of the small round hole 3.2 is larger than the diameter of the second metallization via B, so that the second metallization via B passes through the small round hole 3.2 without connecting to the second metal layer 3, and the second metal layer 3 is connected to the anodes of all varactor diodes through the first metallization via A. The feeding network layer 5 is composed of 8 feeders 5.1, and each feeder is connected to the cathodes of the varactor diodes in a column of metasurface cells through the second metallization via B.

[0040] In an embodiment of the present invention, as Figure 4As shown, the period p of the metasurface unit is 20 mm. The structures of its first metal layer and third metal layer are the same, and each is composed of a slotted circular patch and a patch diode soldered in the middle of the slot. Among them, the diameter w3 of the circular patch is 18 mm, the width w1 of the slot is 0.65 mm, and the model of the varactor diode is MA46H120. This layer of metal is equivalent to a variable capacitor for x-polarized incident electromagnetic waves.

[0041] In an embodiment of the present invention, as Figure 2 shown, the anodes of the varactor diodes in the first and third metal layers are connected to the second metal layer through the first metallized via A, and the cathodes are connected to the feeder layer through the second metallized via B.

[0042] In an embodiment of the present invention, the diameters l1 of the first metallized via A and the second metallized via B are 0.6 mm, and the distance between them is w2 = 12 mm. However, the parameters of the vias are not limited to this.

[0043] In an embodiment of the present invention, as Figure 5 shown, the second metal layer is composed of a copper layer with a circular hole dug in the center. The diameter l2 of the circular hole is 8.5 mm. This layer of metal is equivalent to an inductor for x-polarized incident electromagnetic waves. However, the shape and parameters of the dug hole are not limited to this.

[0044] In an embodiment of the present invention, both the first dielectric layer and the second dielectric layer use Rogers RO4350B plates, with a dielectric constant of 3.48, a tangent loss angle of 0.0037, and a thickness of 1.524 mm. However, the dielectric substrate is not limited to these electromagnetic parameters.

[0045] In an embodiment of the present invention, the prepreg layer uses Rogers RO4450F plates, with a dielectric constant of 3.52, a loss tangent of 0.004, and a thickness of 0.1 mm. However, the prepreg is not limited to these electromagnetic parameters..

[0046] In an embodiment of the present invention, the three metal layers of the metasurface unit are equivalent to a second-order band-pass filter as Figure 6 shown. When the capacitance value of the varactor diode is changed, the transmission performance of the metasurface unit will change. Its amplitude and phase at 5.8 GHz change with the capacitance value as Figure 7 shown. It can be seen that this metasurface can achieve a 180° analog phase change, and the transmission amplitude is within -3 dB.

[0047] In an embodiment of the present invention, the distance between the feed horn and the center of the metasurface is 100 mm. However, the position of the feed horn relative to the metasurface is not limited to this.

[0048] In an embodiment of the present invention, as Figure 8As shown, since the feed horn emits spherical waves, the amplitude and phase of the electromagnetic waves received by each unit of the metasurface are different. According to the array theory, by reasonably controlling the compensation phase of the metasurface units, the electromagnetic waves passing through the metasurface can be controlled.

[0049] For the transmissive analog metasurface of the present invention, since the adjustable range of the unit transmission phase is 180°, perfect compensation can be achieved for the compensation phase in the range of -90° to 90°. For the compensation range of -180° to -90°, compensation is performed at -90°, and for the compensation range of 90° to 180°, compensation is performed at 90°.

[0050] In an embodiment of the present invention, as Figure 8 shown, the near-field distribution at 30° beam deflection is given. It can be seen that the metasurface converts the spherical waves incident on the horn antenna into quasi-plane waves in the 30° direction. However, the beam angles that the metasurface can control are not limited to 30°.

[0051] Matters not covered in the present invention are well-known techniques.

[0052] The above embodiments are only used to illustrate the technical concept and features of the present invention, and their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly. It should not be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. An analog reconfigurable transmissive metasurface for beam control in the C-band, characterized in that, the metasurface is composed of a number of sub-wavelength scale metasurface units; the structure of the metasurface unit from top to bottom is the first metal layer (1), the first dielectric layer (2), the second metal layer (3), the prepreg layer (4), the feeding network layer (5), the second dielectric layer (6) and the third metal layer (7); the first metal layer (1) and the third metal layer (7) both include slotted metal patches (1.1) and varactor diodes (1.2); the second metal layer (3) is composed of a metal plane with a central hole; the feeding network layer (5) is composed of N feed lines (5.1), and each feed line is connected in series with the varactor diodes on N metasurface units. The anode of the varactor diode (1.2) is connected to the second metal layer (3) through the first metallization via hole (A), and the cathode is connected to the feeding network layer (5) through the second metallization via hole (B), where N is a natural number; the first metal layer (1) and the third metal layer (7) have the same structure, both being middle-slotted metal patches, and the anodes and cathodes of the varactor diodes are respectively connected to the metal patches on both sides of the slot.

2. The analog reconfigurable transmissive metasurface for beam control in the C-band according to claim 1, characterized in that, a large round hole (3.1) is opened in the center of the second metal layer (3), and a small round hole (3.2) is opened beside the large round hole. The diameter of the small round hole (3.2) is larger than the diameter of the second metallization via hole (B), so that the second metallization via hole (B) passes through the small round hole (3.2) without being connected to the second metal layer (3), and the second metal layer (3) is connected to the anodes of all varactor diodes through the first metallization via hole (A).

3. The analog reconfigurable transmissive metasurface for beam control in the C-band according to claim 1, characterized in that, the feeding network layer (5) is composed of N feed lines (5.1), and each feed line is connected to the cathodes of the varactor diodes of a column of metasurface units through the second metallization via hole (B).

4. The analog reconfigurable transmissive metasurface for beam control in the C-band according to claim 1, characterized in that, for the first metal layer (1) and the third metal layer (7), the metal patches are circular with a diameter of 18 mm, and the width of the slot in the patch is 0.65 mm.

5. The analog reconfigurable transmissive metasurface for beam control in the C-band according to claim 1, characterized in that, for the second metal layer (3), the shape of the central hole is circular with a diameter of 8.5 mm.

6. The analog reconfigurable transmissive metasurface for beam control in the C-band according to claim 1, characterized in that, the first dielectric layer (2), the prepreg layer (4), and the second dielectric layer (6) all adopt microwave circuit boards.

7. The analog reconfigurable transmissive metasurface for beam control in the C-band according to claim 6, characterized in that, The dielectric constant of the microwave circuit board used for the first dielectric layer (2) and the second dielectric layer (6) is 3.48, the tangent of the loss angle is 0.0037, and the thickness is 1.524 mm.

8. The analog reconfigurable transmissive metasurface for beam control in the C-band according to claim 6, characterized in that, the dielectric constant of the microwave circuit board used for the prepreg layer (4) is 3.52, the tangent of the loss angle is 0.004, and the thickness is 0.1 mm.

9. The analog reconfigurable transmissive metasurface for beam control in the C-band according to claim 1, characterized in that, the varactor diode model is MA46H120, and the capacitance value change range is 0.14~1.2 pF.

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