Dual-frequency orthogonal polarization ultra-thin planar huygens super surface lens

Abstract

The application discloses a kind of dual-frequency orthogonal polarized ultra-thin plane Huygens metasurface lens, by parallel double-layer dipole pair Huygens unit, sliding double-layer dipole pair Huygens unit two kinds of metasurface units are integrated in the two sides of same layer dielectric substrate, with convex lens phase arrangement and orthogonal polarization direction.Compared with prior art, the dual-frequency orthogonal polarization Huygens metasurface lens formed has a great frequency ratio;And the length of the sliding double-layer dipole pair Huygens unit of goat horn shape can not only reduce the mutual coupling capacitance of the two kinds of units, but also shorten, provide more space for parallel double-layer dipole pair Huygens unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave technology, in particular to a double-frequency orthogonal polarization ultra-thin planar Huygens super surface lens. BACKGROUND

[0002] The planar lens antenna is a kind of air-fed array antenna, which is composed of a feed source and a planar lens. The lens part is an array of large-scale sub-wavelength units, which mainly compensates the spherical wave of the feed source radiation through resonance phase to make it into a plane wave, so as to achieve the purpose of improving the gain. Unlike phased array antennas using direct feeding, on the one hand, planar lens antennas using air-fed do not need complex feed networks, so there is no line loss of the feed network, and therefore high gain can be more easily achieved. On the other hand, as the frequency increases, the cost of the feed network and T / R components of the phased array also increases significantly, while the planar lens antenna does not need a feed network, and the lens can be manufactured by planar circuit technology, so it can maintain a low manufacturing cost at high frequencies. In addition, the planar lens antenna also has the advantages of light weight, flexible wavefront manipulation, etc. With further research, the planar lens antenna has also realized functions such as frequency modulation, polarization modulation, surface wave modulation, etc. that traditional dielectric lens antennas cannot achieve, and has a wide application prospect in satellite communication, 5G, radar detection, etc.

[0003] In the prior art, the planar ultra-thin Huygens super surface lens can only work at double frequencies at a small frequency ratio. In order to further improve the frequency and polarization control capability of the Huygens super surface lens and meet the frequency requirements of various application scenarios such as satellite communication, radar detection and 5G, a double-frequency orthogonal polarization planar ultra-thin Huygens lens with a larger frequency ratio is urgently needed. SUMMARY

[0004] Therefore, the purpose of the embodiments of the present application is to provide a double-frequency orthogonal polarization planar ultra-thin Huygens super surface lens with a large frequency ratio based on parallel double-layer dipole pair Huygens units and sliding double-layer dipole pair Huygens units, and to reduce the mutual influence when the size of the two units is tuned.

[0005] The present application provides a double-frequency orthogonal polarization ultra-thin planar Huygens super surface lens, which comprises 18x18 parallel double-layer dipole pair Huygens units arranged in a convex lens phase manner, and 36x36 sliding double-layer dipole pair Huygens units; the parallel double-layer dipole pair Huygens units and the sliding double-layer dipole pair Huygens units are integrated on both sides of the same layer of dielectric substrate, arranged in a convex lens phase and orthogonal polarization direction.

[0006] The parallel double-layer dipole pair Huygens unit is composed of three pairs of strip dipole pairs, and the sliding double-layer dipole pair Huygens unit is composed of a pair of horn dipole pairs with the same size but with a certain dislocation between the upper layer and the lower layer.

[0007] Preferably, the parallel double-layer dipole pair Huygens unit is used to generate polarized Huygens resonance, and tune the vertically polarized electromagnetic wave.

[0008] Preferably, the sliding double-layer dipole pair Huygens unit is used to generate polarized Huygens resonance orthogonal to the parallel double-layer dipole pair Huygens unit, and tune the horizontally polarized electromagnetic wave.

[0009] Preferably, the upper and lower dipoles of the sliding double-layer dipole pair Huygens unit slide through dislocation to reduce the interlayer capacitance Cm, so as to move the magnetic resonance to a high frequency.

[0010] Preferably, the unit period size and the substrate thickness of the sliding double-layer dipole pair Huygens unit are greater than those of the parallel double-layer dipole pair Huygens unit.

[0011] In the scheme of the present application, the dual-frequency orthogonal polarization ultra-thin planar Huygens metasurface lens includes 18*18 parallel double-layer dipole pair Huygens units arranged in a convex lens phase mode and 36*36 sliding double-layer dipole pair Huygens units; the parallel double-layer dipole pair Huygens units and the sliding double-layer dipole pair Huygens units are integrated on both sides of the same layer of dielectric substrate, arranged in a convex lens phase mode and orthogonal in polarization direction; the upper layer and the lower layer of the parallel double-layer dipole pair Huygens unit are consistent in structure and composed of three pairs of strip dipole pairs; the sliding double-layer dipole pair Huygens unit is composed of a pair of horn dipole pairs with the same size but with a certain dislocation between the upper layer and the lower layer. Compared with the prior art, the dual-frequency orthogonal polarization Huygens metasurface lens composed of the parallel double-layer dipole pair Huygens unit and the sliding double-layer dipole pair Huygens unit integrated on both sides of the same layer of dielectric substrate, arranged in a convex lens phase mode and orthogonal in polarization direction, has a great frequency ratio; and the horn-shaped sliding double-layer dipole pair Huygens unit not only can reduce the mutual coupling capacitance of the two kinds of units, but also can shorten the length of the sliding double-layer dipole pair Huygens unit, so as to provide more space for the parallel double-layer dipole pair Huygens unit. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. Other related drawings can also be obtained by those skilled in the art without creative labor.

[0013] Figure 1 A schematic diagram of the overall structure of the Huygens super surface lens embodiment of the present application;

[0014] Figure 2 A schematic diagram of the TPBDP unit of the present application embodiment;

[0015] Figure 3 A schematic diagram of the GSBDP unit of the present application embodiment;

[0016] Figure 4 A schematic diagram of the equivalent circuit of the TPBDP unit of the present application embodiment;

[0017] Figure 5 A schematic diagram of the equivalent circuit of the GSBDP unit of the present application embodiment;

[0018] Figure 6 A schematic diagram of the variation of the electric resonance frequency and the magnetic resonance frequency of the GSBDP unit of the present application embodiment with sliding distance;

[0019] Figure 7 A frequency response curve of the TPBDP unit of the present application embodiment in Huygens resonance;

[0020] Figure 8 A frequency response curve of the GSBDP unit of the present application embodiment in Huygens resonance;

[0021] Figure 9 A design flow of the dual-frequency orthogonal polarization planar ultra-thin Huygens lens of the present application embodiment;

[0022] Figure 10 A schematic diagram of electromagnetic wave modulation of the dual-frequency orthogonal polarization planar ultra-thin Huygens lens of the present application embodiment considering the placement of the feed source;

[0023] Figure 11 The phase theoretical value of the horizontally polarized GSBDP unit and the vertically polarized TPBDP unit when the dual-frequency orthogonal polarization planar ultra-thin Huygens lens of the present application embodiment considers the placement of the feed source;

[0024] Figure 12 The radiation pattern of the dual-frequency orthogonal polarization planar ultra-thin Huygens lens of the present application embodiment after loading the feed source. DETAILED DESCRIPTION

[0025] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example implementations to those skilled in the art.

[0026] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the technology can be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, devices, implementations, and operations have not been shown or described in detail to avoid obscuring aspects of the application.

[0027] The block diagrams in the drawings show only the functionality of the features and can not imply that the functionality must be implemented in the order shown. Some or all of the features can be implemented in hardware, software, or other functional components or modules, or combinations thereof. The functionality of the features can be combined or distributed in any suitable manner.

[0028] The flow diagrams show the functionality of the features and can not imply a strict logical order to the steps. Some or all of the steps shown can be combined or divided into sub-steps, or some of the steps can be omitted, or some of the steps can be performed in a different order.

[0029] It is noted that "a plurality" refers to two or more.

[0030] The planar lens is generally realized by true time delay line, super surface or metamaterial, etc. To ensure efficient modulation of the wave front of the feed source, each array unit constituting the lens is generally required to achieve full-cycle phase coverage (360°) with high transmission amplitude through size tuning. In 2014, A. H. Abdelrahman of the University of Mississippi, A. Z. Elsherbeni of the Colorado School of Mines and Fan Yang of Tsinghua University jointly published an article entitled "Transmission phase limit of multilayer frequency-selective surfaces for transmitarray designs" in the IEEE Transactions on Antennas and Propagation (vol. 62, no. 2, pp. 690-697, Feb. 2014). The conclusion derived is that the unit constituting the planar lens needs at least 3 metal layers to achieve 360° phase coverage with a transmission loss of less than 3 dB. According to this conclusion, the traditional planar lens needs at least 3 metal layers to meet the performance requirements. However, this condition of three layers of metal reduces the integration of the planar lens, especially in satellite communication or 5G communication and other long-distance mobile communication occasions that require low cost and high integration, the planar lens is difficult to integrate with the platform shell or to design a curved surface.

[0031] In 2013, Carl Pfeiffer of the University of Michigan published an article entitled "Metamaterial Huygens'surfaces: tailoring wave fronts with reflectionless sheets" in the Physical Review Letter (vol. 110, no. 19, pp. 197401, May 2013). A new type of Huygens super surface is proposed. The article points out that when the surface impedance characteristics of the super surface, i.e. the electric admittance (Y es ) and the magnetic impedance (Z ms ) satisfy (1) (η is the wave impedance of free space), the super surface exhibits ideal reflectionless characteristics, and the solution that traverses (1) can achieve 360° phase coverage.

[0032] Z ms / η=Y es η (1)

[0033] Further, in 2019, the Cui Tiejun research group of Southeast University published an article titled "High-transmission ultrathin Huygens' metasurface with 360° phase control by using double-layer transmitarray elements" in the journal Physical Review Applied (vol. 12, no. 2, p. 024012, 2019). In this article, the electric resonance circuit generating electric admittance and the magnetic resonance circuit generating magnetic impedance were integrated on the upper and lower surfaces of the same layer of printed circuit board, and 360° phase coverage was achieved using double-layer metal elements. Since then, a series of Huygens super surface units with double-layer metal structure have been introduced. In 2021, the Zhi Ning Chen research group of the National University of Singapore published an article titled "High Efficiency Metalens Antenna Using Huygens' Metasurface with Glide Symmetric I-shape Metal Strips" in the journal IEEE Transactions on Antennas and Propagation (vol. 69, no. 11, pp. 7394-7403, Nov. 2021). A kind of ultrathin Huygens super surface unit was proposed, which realized high transmission amplitude and 360° phase coverage using a pair of glide symmetric double-layer dipole pairs.

[0034] According to literature reports, there are currently two main ways to achieve Huygens resonance. One is the Huygens super surface unit with anti-symmetric structure, which introduces magnetic resonance through anti-symmetric branches. This unit is thin and has a small unit period, but it is difficult to achieve dual-polarized Huygens resonance; the second is the glide symmetric or chain arrangement of double-layer dipole pair units, which have high transmission amplitude and are easy to achieve dual-polarized Huygens resonance, but the unit period is large and thick. In 2022, we proposed an invention patent titled "A double-layer metal planar ultrathin Huygens super surface unit". This invention takes the number and spacing of double-layer parallel dipole pairs in the unit period as degrees of freedom, achieving a dual-polarized Huygens super surface unit with a smaller period and thinner thickness.

[0035] However, most of the existing ultra-thin Huygens metasurface unit technology can only achieve Huygens resonance at point frequency, and the advantages of electromagnetic wave modulation at wide frequency and multi-frequency are not reflected. In 2022, Chunhua Xue of Guangxi University of Science and Technology published an article entitled "An ultrathin dual-band Huygens' meta-lens antenna with orthogonal linear polarization" in IEEE Antennas and Wireless Propagation Letters, which proposes to arrange two groups of sliding symmetric double-layer dipole pairs orthogonally, and realizes an ultra-thin dual-band orthogonal polarization Huygens metasurface lens with two layers of metal. The Huygens metasurface lens has dual-band orthogonal polarization transmission characteristics, but the two frequencies are not much different, and the frequency ratio is 1.35.

[0036] The embodiment provides an ultra-thin planar Huygens metasurface lens with dual-band orthogonal polarization, which comprises 18x18 parallel double-layer dipole pair Huygens units arranged in a convex lens phase mode and 36x36 sliding double-layer dipole pair Huygens units.

[0037] Specifically, the overall structure of the dual-band orthogonal polarization ultra-thin planar Huygens metasurface lens of the embodiment is as shown in Figure 1 , wherein the lens is composed of 18x18 vertically polarized parallel double-layer dipole pair Huygens units (denoted as TPBDP units), 36x36 horizontally polarized sliding double-layer dipole pair Huygens units (denoted as GSBDP units). The structure diagram of the TPBDP unit is as shown in Figure 2 , and the structure diagram of the GSBDP unit is as shown in Figure 3 . The plate material of the Huygens metasurface lens medium substrate is Rogers RO4350B, the relative dielectric constant ε r = 3.66, the loss tangent tan δ = 0.0037, and the thickness is 1.524 mm.

[0038] Further, the parallel double-layer dipole pair Huygens units and the sliding double-layer dipole pair Huygens units are integrated on both sides of the same layer of medium substrate, arranged in a convex lens phase and orthogonal polarization direction.

[0039] As shown in Figure 2 , the upper layer and the lower layer structure of the parallel double-layer dipole pair Huygens unit (TPBDP unit) are consistent, which is composed of 3 pairs of strip dipole pairs; as shown in Figure 3 , the sliding double-layer dipole pair Huygens unit (GSBDP unit) is composed of a pair of size consistent but with a certain offset of the upper layer and the lower layer of the goat horn-shaped dipole pair.

[0040] Preferably, the parallel double-layer dipole pair Huygens unit is used to generate a polarized Huygens resonance, which is tuned to vertical polarized electromagnetic waves.

[0041] Specifically, in this embodiment, the TPBDP unit generates a polarized Huygens resonance (in this case, vertical polarization), which is tuned to vertical polarized electromagnetic waves, as shown in Figure 4 Compared with the single parallel double-layer dipole pair unit, the three parallel double-layer dipole pairs increase the same-layer capacitance Ce, so that the electric resonance frequency moves to the same frequency as the magnetic resonance, thus eliminating the need for thickness tuning or increasing the unit period, thereby realizing a smaller unit.

[0042] Preferably, the sliding double-layer dipole pair Huygens unit is used to generate a polarized Huygens resonance that is orthogonal to the parallel double-layer dipole pair Huygens unit, which is tuned to horizontal polarized electromagnetic waves.

[0043] Preferably, the upper and lower dipoles of the sliding double-layer dipole pair Huygens unit are offset to slide to reduce the interlayer capacitance Cm, so that the magnetic resonance moves to a high frequency.

[0044] Specifically, in this embodiment, the GSBDP unit generates a polarized Huygens resonance (in this case, horizontal polarization) that is orthogonal to the TPBDP unit, which is tuned to horizontal polarized electromagnetic waves, as shown in Figure 5

[0045] Unlike the TPBDP unit, the upper and lower dipoles of the GSBDP unit need to be offset to slide to reduce the interlayer capacitance Cm, so that the magnetic resonance moves to a high frequency, as shown in Figure 6 , so that the electric resonance is at the same frequency as the magnetic resonance.

[0046] Preferably, the unit period size and substrate thickness of the sliding double-layer dipole pair Huygens unit are greater than those of the parallel double-layer dipole pair Huygens unit.

[0047] Specifically, in this embodiment, according to the Nyquist sampling law, to ensure effective tuning of electromagnetic waves, the unit period cannot be greater than half the wavelength, so the substrate thickness should be increased to reduce Cm while the dipole pairs are sliding. That is, the unit period size and substrate thickness required for the GSBDP unit to achieve Huygens resonance are greater than those of the TPBDP unit.

[0048] In addition, this embodiment further proposes a design process of a dual-frequency orthogonal polarization ultra-thin planar Huygens metasurface lens, and a process flowchart thereof is shown in Figure 9

[0049] Step 1: Develop a TPBDP unit design.

[0050] ​​Specifically, in this embodiment, the TPBDP unit is designed to be vertically polarized. If designed to be horizontally polarized, the steps are the same, just rotate the unit on the dielectric plate by 90 degrees.

[0051] In this step, the working frequency of the TPBDP unit should be determined first, such as Figure 2 As shown, the unit is composed of three pairs of double-layer dipoles, and full-wave simulation software CST is used to simulate under the boundary conditions of the unit cell combined with the frequency domain solver. By tuning the dipole lengths L1, L2 and the dipole spacing s, the electric resonance frequency f e and the magnetic resonance frequency f m are tuned to achieve the same frequency at the design target frequency. Further, fine-tune the above parameters to avoid mutual coupling between the electric resonance and the magnetic resonance, and achieve Huygens resonance. In this embodiment, the Huygens resonance frequency of the TPBDP unit is designed to be 8.8 GHz.

[0052] Step 2, carry out GSBDP unit design.

[0053] Specifically, in this embodiment, the GSBDP unit is designed to be horizontally polarized. If designed to be vertically polarized, the steps are the same, just rotate the unit on the dielectric plate by 90 degrees, which is orthogonal to the polarization of the TPBDP unit.

[0054] As shown in Figure 3 , the spacing between the upper and lower layers of the GSBDP unit is determined by the thickness of the substrate of the TPBDP unit designed in the first step. The same as the simulation setting of the TPBDP unit, by tuning the dipole length LH, phi1 and the sliding distance d, Huygens resonance is achieved. It should be noted that the period of the GSBDP unit should not be greater than the spacing s of the dipoles of the TPBDP unit. In this embodiment, the Huygens resonance frequency of the GSBDP unit is designed to be 30 GHz.

[0055] Step 3, carry out Huygens metasurface lens design.

[0056] Further, arrange the two kinds of units with the phase distribution of formula (2) respectively

[0057]

[0058] where k0 is the wave number in free space, R MN is the position of the (m, n)th unit of the lens from the focal point (feed source), is the position vector of the (m, n)th unit of the lens, is the beam pointing, is the reference phase.

[0059] In this embodiment, as shown in Figure 10XB-HA112-10K and XB-HA34-10S type 10-dB standard gain horn as the feed source, the focal ratio is 0.5, and the overall size of the Huygens super surface lens is 180x180x1.5mm 3 Two feed horns use a bias feed design, and the lens phase is also designed to be defocused to compensate for the gradient spatial phase generated by the bias feed, so that the beam is directed to the edge direction. The unit phase arrangement of the lens is as shown in Figure 11 The lens radiation pattern at 8.8GHz and 30GHz is shown in Figure 12 (a) and Figure 12 (b), respectively.

[0060] Those skilled in the art can realize that the units and steps of the examples described in combination with the embodiments disclosed herein can be realized in electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in the above description in general terms. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0061] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or software functional unit.

[0062] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A dual-frequency orthogonally polarized ultrathin planar Huygens metasurface lens, characterized in that, The lens includes 18×18 parallel double-layer dipole pair Huygens units arranged in a convex lens phase configuration, and 36×36 sliding double-layer dipole pair Huygens units; the parallel double-layer dipole pair Huygens units and the sliding double-layer dipole pair Huygens units are integrated on both sides of the same dielectric substrate, arranged in a convex lens phase configuration, and their polarization directions are orthogonal. The upper and lower layers of the parallel double-layer dipole pair Huygens unit have the same structure and consist of 3 pairs of strip dipole pairs; the sliding double-layer dipole pair Huygens unit consists of a pair of ram's horn-shaped dipole pairs with the same size but with a certain misalignment between the upper and lower layers. The parallel double-layer dipole pair Huygens unit is used to generate vertically polarized Huygens resonance and tune vertically polarized electromagnetic waves. The sliding double-layer dipole pair Huygens unit is used to generate Huygens resonance with polarization orthogonal to the parallel double-layer dipole pair Huygens unit, and to tune horizontally polarized electromagnetic waves. The parallel double-layer dipole pair Huygens unit and the sliding double-layer dipole pair Huygens unit are respectively arranged with the phase distribution of the following formula: Where k0 is the wave number of free space, R MN It represents the position of the (m,n)th element of the lens from the focal point. It is the position vector of the (m,n)th unit of the lens. φ0 is the beam direction and φ0 is the reference phase.

2. The dual-frequency orthogonally polarized ultrathin planar Huygens metasurface lens according to claim 1, characterized in that, The sliding double-layer dipole reduces the interlayer capacitance Cm by misaligning the upper and lower layer dipoles of the Huygens unit, thereby shifting the magnetic resonance to a higher frequency.

3. The ultrathin planar Huygens metasurface lens with dual-frequency orthogonal polarization according to claim 2, characterized in that, The cell period size and substrate thickness of the sliding double-layer dipole pair Huygens cell are greater than those of the parallel double-layer dipole pair Huygens cell.

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