Low-frequency-band variable polarization adjustable metasurface unit and application thereof

Abstract

The invention relates to the technical field of microwaves, and discloses a low-frequency-band variable polarization adjustable metasurface unit and application thereof.The low-frequency-band variable polarization adjustable metasurface unit comprises metal layers, dielectric layers, metal columns, variable capacitance diodes and chip inductors, the four metal layers are sequentially arranged in the thickness direction, and every two adjacent metal layers are isolated through the corresponding dielectric layer; the first metal layer comprises a first metal structure and a second metal structure and is used for controlling the phase and polarization of reflected electromagnetic waves; the variable capacitance diode is arranged between the first metal structure and the second metal structure and is used for changing the phase of the reflected electromagnetic wave; the second metal layer is a metal floor and is used for reflecting electromagnetic waves; the third metal layer and the fourth metal layer are feed layers; the metal columns are feed columns and are used for connecting different metal layers; and the chip inductor is positioned on the fourth metal layer and is used for isolating the radio-frequency current. On the basis of realizing miniaturization of a low-frequency band, joint dynamic regulation and control on two key dimensions of phase and polarization of electromagnetic waves are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave technology, in particular, to a low-frequency variable polarization tunable metasurface unit and application thereof. BACKGROUND

[0002] In recent years, intelligent metasurface technology has attracted widespread attention in the field of wireless communication due to its ability to flexibly regulate electromagnetic wave characteristics. Intelligent metasurfaces are usually composed of a large number of tunable metasurface units arranged periodically. By applying control signals to the tunable elements in the units, dynamic regulation of spatial electromagnetic waves can be achieved, including phase, amplitude, polarization, and frequency, thereby constructing a programmable wireless communication environment and significantly improving the performance of communication systems.

[0003] Currently, the design of tunable metasurface units is mainly oriented towards high-frequency communication applications, with a high operating frequency band generally above the L band to meet the high-capacity and high-speed communication requirements. At the same time, to simplify the unit structure and control mechanism, most existing designs only support phase regulation. However, such tunable metasurface units still have obvious limitations in practical applications: on the one hand, their high operating frequency band and relatively large unit size make them unsuitable for emergency communication, tactical communication, and other scenarios that require low-frequency bands (such as below 1000MHz); on the other hand, due to the lack of control over multiple electromagnetic parameters such as polarization, they are difficult to meet the application requirements of anti-interference in complex communication environments, limiting the applicability and performance potential of intelligent metasurfaces in a wider range of wireless systems.

[0004] Therefore, it is urgent to develop a tunable metasurface unit that operates at low frequencies, has a small size, and can simultaneously regulate phase and polarization, to expand the application capabilities of intelligent metasurfaces in low-frequency communication and complex scenarios. SUMMARY

[0005] The present application provides a low-frequency variable polarization tunable metasurface unit and application thereof. By setting multiple layers of metal layers isolated from each other, connecting different metal layers with feed columns, and loading varactor diodes between the first and second metal structures, the electromagnetic response characteristics of the unit structure are dynamically regulated by the change in capacitance value, achieving efficient joint regulation of reflected electromagnetic wave phase and polarization in the low-frequency band below 1000MHz. This effectively solves the technical problems of existing tunable metasurface units, such as high operating frequency band, large size, and inability to adapt to low-frequency communication scenarios, as well as single controllable electromagnetic parameters that make it difficult to meet the complex application requirements of anti-interference.

[0006] According to one aspect of the present application, a low-frequency variable polarization adjustable metasurface unit is provided, comprising a metal layer, a dielectric layer, a metal column, a varactor diode and a patch inductor, the metal layer is arranged in sequence along the thickness direction and has four layers, and the adjacent two layers of metal layers are isolated by the dielectric layer; the first layer of metal layer comprises a first metal structure and a second metal structure, and is used for controlling the phase and polarization of reflected electromagnetic waves; the varactor diode is arranged between the first metal structure and the second metal structure, and is used for changing the phase of reflected electromagnetic waves; the second layer of metal layer is a metal ground plate and is used for reflecting electromagnetic waves; the third layer of metal layer and the fourth layer of metal layer are both feed layers; the metal column is a feed column and is used for connecting different metal layers; and the patch inductor is located on the fourth layer of metal layer and is used for blocking radio frequency current.

[0007] Further, the first metal structure is arranged in the middle of the first layer of metal layer, and the first metal structure is an octagonal metal structure; the second metal structure comprises four fishbone-shaped metal structures, the tail end of the fishbone-shaped metal structure is arranged perpendicular to the edge strip of the octagonal metal structure, and one fishbone-shaped metal structure is arranged on the octagonal metal structure at an interval of one edge strip, and the head end of the four fishbone-shaped metal structures is arranged in sequence and forms a square contour structure.

[0008] Further, the varactor diode is located on the diagonal line of the first layer of metal layer, and two varactor diodes are arranged on each diagonal line of the first layer of metal layer, and there are a total of four varactor diodes.

[0009] Further, the four fishbone-shaped metal structures and the octagonal metal structure are connected through the varactor diode, the negative electrode of the varactor diode is welded on the octagonal metal structure, and the positive electrode of the varactor diode is welded on the fishbone-shaped metal structure; by loading the varactor diode on the angularly symmetrical fishbone-shaped metal structure, the adjustable metasurface unit not only has low working frequency and small size, but also can efficiently and dynamically control the phase and polarization of reflected electromagnetic waves, and realize the joint control effect of multiple electromagnetic parameters.

[0010] Further, the metal column is provided with five metal columns, including one center column located at the center position and four peripheral columns located outside the center column; the center column penetrates through the first layer of metal layer to the second layer of metal layer and is used for grounding; the peripheral column penetrates through the first layer of metal layer to the fourth layer of metal layer and is used for feeding; four circular holes are etched on the second layer of metal layer, the circular holes are arranged one by one corresponding to the peripheral column, and the peripheral column penetrates through the circular hole and isolates the second layer of metal layer from the peripheral column.

[0011] Further, the third layer of metal layer is a metal feed line, which connects two diagonal peripheral columns in the first group; the fourth layer of metal layer is a metal feed line, which firstly connects two diagonal peripheral columns in the second group, and then respectively leads out feed lines from one metal column selected from the two diagonal peripheral columns in the first group and one metal column selected from the two diagonal peripheral columns in the second group, and welds patch inductors on the feed lines, which are used for connecting control circuits and avoiding radio frequency current flowing into control power supply.

[0012] Further, the dielectric layer is a common printed circuit board, and the common printed circuit board adopts a microstrip PCB board with a dielectric constant interval of 1-10 and a magnetic permeability of 1; or the dielectric layer is a hard foam layer, and the foam is polystyrene foam.

[0013] Further, the dielectric layer is provided with four layers, the first layer of dielectric layer and the second layer of dielectric layer are arranged between the first layer of metal layer and the second layer of metal layer, the third layer of dielectric layer is arranged between the second layer of metal layer and the third layer of metal layer, and the fourth layer of dielectric layer is arranged between the third layer of metal layer and the fourth layer of metal layer.

[0014] Further, the dielectric layer has a board surface size of 90mm*90mm and a thickness size of 0.2mm-10mm.

[0015] According to another aspect of the present application, there is also provided an application of a low-frequency variable polarization adjustable metasurface unit, which is used for constructing a low-frequency compact intelligent metasurface by periodically arranging the low-frequency variable polarization adjustable metasurface unit, and is used for emergency communication or tactical wireless communication.

[0016] The present application has the following beneficial effects: 1. Realize low-frequency operation and miniaturization: the first layer of metal layer adopts a specific metal structure (such as a combination of fishbone and octagonal structure), which effectively increases the electrical length of the surface current path through its geometric shape, thereby significantly reducing the electromagnetic resonance frequency of the variable polarization adjustable metasurface unit in a limited physical size, enabling it to stably work in a low-frequency band below 1000MHz, while maintaining the miniaturization characteristics of the variable polarization adjustable metasurface unit, solving the problem that existing high-frequency metasurface units cannot adapt to low-frequency application scenarios such as emergency communication.

[0017] 2. Realize joint regulation of phase and polarization: by integrating varactor diodes between diagonally symmetrical metal structures, the continuous variable characteristics of the capacitance value of the varactor diodes can dynamically and reconfigurably adjust the electromagnetic response of the unit structure, enabling the variable polarization adjustable metasurface unit to dynamically regulate a wide range of phases of incident electromagnetic waves, and further enabling flexible manipulation of the polarization state of reflected waves (for example, switching between linear polarization and circular polarization) through control of structural symmetry, thereby overcoming the limitation of existing technologies that mostly only regulate phase but lack polarization control dimension.

[0018] 3. Guarantee the stability of the radio frequency performance and the circuit: The multi-metal layer stack structure is isolated by the dielectric layer, and the matched interconnection relationship between different metal layers is realized through the metal column. It provides a low-loss feeding path for the DC bias circuit, effectively reduces the interference of the DC control line on the high-frequency radio frequency performance, and ensures the stability and reliability of the variable polarization adjustable metasurface unit during the regulation process. The metal floor provides an efficient reflection interface for electromagnetic waves, ensuring the reflection efficiency of the variable polarization adjustable metasurface unit.

[0019] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings that form a part of the present application are used to provide a further understanding of the present application, the schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings: Figure 1 is a structure side view of a low-frequency miniaturized variable polarization adjustable metasurface unit of a preferred embodiment of the present application; it should be noted that this schematic diagram is used to clearly show the structure of the adjustable metasurface unit, and there is no gap between the four metal layers and the four dielectric layers in practice.

[0021] Figure 2 is a top view of the four metal layers of the adjustable metasurface unit of the preferred embodiment of the present application, in which the bright color is metal, the dark gray color is dielectric, and the black color is varactor diode or patch inductor; wherein, Figure 2 (a) is the first metal layer, in which the black color is the varactor diode, and the five circular holes are the positions of the five metal columns; Figure 2 (b) is the second metal layer, in which the bright color circle is the position of the metal column, and the four circular rings are the etched metal to isolate the metal floor and the four metal columns; Figure 2 (c) is the third metal layer, in which one pair of diagonal metal columns of the four metal columns are connected by a metal feeding line; Figure 2 (d) is the fourth metal layer, in which the black square is the patch inductor, and is different from Figure 2 (c) in which the other pair of diagonal metal columns are connected by a metal feeding line, and one metal column is selected from each of the two pairs of diagonal metal columns, and is led out through the metal feeding line after the patch inductor.

[0022] Figure 3 is the performance curve of the adjustable metasurface unit of the preferred embodiment of the present application; wherein Figure 3 (a),Figure 3 (b) are the reflectivity and reflection phase curves of the tunable metasurface unit respectively when the polarization is not transformed; Figure 3 (c), Figure 3 (d) are the reflectivity and reflection phase curves of the tunable metasurface unit respectively when the polarization is transformed orthogonally; Figure 3 (e), Figure 3 (f) are the reflectivity and reflection phase curves of the tunable metasurface unit respectively when the polarization is transformed from linear to circular. 00, 01, 10, 11 in the figure respectively represent four typical unit states, corresponding to four different unit control strategies, to form 2-bit phase control effects under different polarization transformations.

[0023] Legend: 101, first metal layer; 1011, first metal structure; 1012, second metal structure; 102, second metal layer; 1021, circular hole; 103, third metal layer; 104, fourth metal layer; 201, first dielectric layer; 202, second dielectric layer; 203, third dielectric layer; 204, fourth dielectric layer; 301, center column; 302, peripheral column; 400, varactor diode; 500, patch inductor. DETAILED DESCRIPTION

[0024] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following.

[0025] As Figure 1 and Figure 2As shown, the low-frequency variable polarization adjustable metasurface unit of the embodiment includes a metal layer, a dielectric layer, a metal column, a varactor diode 400, and a patch inductor 500. The metal layer is sequentially arranged with four layers along the thickness direction, and the adjacent two metal layers are isolated by the dielectric layer. The first layer metal layer 101 includes a first metal structure 1011 and a second metal structure 1012, which are used to control the phase and polarization of the reflected electromagnetic wave. The varactor diode 400 is arranged between the first metal structure 1011 and the second metal structure 1012, and is used to change the phase of the reflected electromagnetic wave. The second layer metal layer 102 is a metal ground plate, which is used to reflect the electromagnetic wave. The third layer metal layer 103 and the fourth layer metal layer 104 are both feed layers. The metal column is a feed column, which is used to connect different metal layers. The patch inductor 500 is located in the fourth layer metal layer 104, and is used to isolate the radio frequency current. The low-frequency variable polarization adjustable metasurface unit of the present application adopts a specific metal structure (such as a combination of fishbone and octagonal structure) in the first layer metal layer 101, which effectively increases the electrical length of the surface current path, thereby significantly reducing the electromagnetic resonance frequency of the variable polarization adjustable metasurface unit in a limited physical size, enabling it to work stably in the low-frequency band below 1000MHz, while maintaining the miniaturization characteristics of the variable polarization adjustable metasurface unit, solving the problem that the existing high-frequency metasurface unit cannot adapt to emergency communication and other low-frequency application scenarios. By integrating the varactor diode 400 between the diagonally symmetrical metal structures, and utilizing the continuous variable characteristics of its capacitance value with the bias voltage, the electromagnetic response of the unit structure can be dynamically and reconfigurably adjusted, enabling the variable polarization adjustable metasurface unit to dynamically control the phase of the incident electromagnetic wave in a wide range, and further realizing flexible manipulation of the polarization state of the reflected wave (for example, switching between linear polarization and circular polarization), thereby overcoming the limitation of the prior art that most of them can only control the phase but lack polarization control dimension. The multi-metal layer stacking structure isolated by the dielectric layer, and the matched interconnection relationship between different metal layers realized by the metal column, provide a low-loss feed path for the direct current bias circuit, while effectively reducing the interference of the direct current control line on the high-frequency radio frequency performance; the patch inductor 500 located in the bottom feed network acts as a radio frequency choke, effectively isolating the leakage of radio frequency signals to the direct current bias network, ensuring the stability and reliability of the variable polarization adjustable metasurface unit during the control process; the metal ground plate provides an efficient reflection interface for the electromagnetic wave, ensuring the reflection efficiency of the variable polarization adjustable metasurface unit. The low-frequency variable polarization adjustable metasurface unit of the present application realizes the joint dynamic control of the phase and polarization of the electromagnetic wave through multi-layer integrated design, successfully realizing the miniaturization in the low-frequency band, effectively solving the technical problems of the prior art that the working frequency is high and the control dimension is single, and improving the application potential of intelligent metasurfaces in complex low-frequency communication scenarios.

[0026] As Figure 1 and Figure 2 shown, in this embodiment, the first metal structure 1011 is disposed in the middle of the first metal layer 101, and the first metal structure 1011 is an octagonal metal structure; the second metal structure 1012 includes four fishbone-shaped metal structures, the tail end of the fishbone-shaped metal structure is perpendicular to the edge of the octagonal metal structure, and an octagonal metal structure is spaced apart by one edge and has one fishbone-shaped metal structure, and the head end of the four fishbone-shaped metal structures is arranged in sequence and constitutes a square contour structure. The first metal structure 1011 adopts an octagonal metal structure in the middle, and its periphery is connected to four fishbone-shaped metal structures through a varactor 400 at intervals. Through a special geometric shape, the effective path of the surface current is greatly extended in a limited unit plane area, thereby significantly increasing the equivalent electrical length of the structure, so that the resonant frequency is reduced to below 1000 MHz, and the miniaturization design goal of the super surface unit working in the low frequency band is successfully achieved. The four fishbone-shaped metal structures are diagonally symmetrically distributed around the central octagonal structure, and through the arrangement mode of spacing one fishbone-shaped metal structure by one edge, a highly symmetric and independently excitable radiation structure is formed. The symmetric structure design of the first metal structure 1011 provides a physical basis for supporting two orthogonal linear polarization (such as x polarization and y polarization) operations. By independently regulating the varactor 400 at the symmetric position, the symmetry of the structure can be destroyed, thereby creating the necessary conditions for dynamically realizing the phase control and polarization rotation of the reflected wave. The head end of the fishbone-shaped metal structure is arranged in sequence and constitutes an external square contour frame, which not only enhances the mechanical stability of the overall metal structure and reduces the processing error, but more importantly, the frame as a shared current path helps to balance and constrain the current distribution on each symmetric branch, so that the unit can produce more consistent and controllable electromagnetic response when excited by electromagnetic waves with different polarization directions, thereby improving the accuracy of regulation and the consistency of unit performance. The layout of the first metal structure 1011, through the symmetric design of its extended fishbone-shaped metal structure combined with the central octagonal metal structure, not only realizes the key premise of low-frequency resonance and small size, but also constructs the structural basis of independently controllable dual-polarization operation, thereby providing a core structural guarantee for finally realizing flexible and dynamic phase and polarization joint regulation.

[0027] As Figure 1 and Figure 2As shown, in the present embodiment, the fishbone-shaped metal structure includes a main skeleton and branch skeletons, the branch skeletons are right-angle metal structures and are symmetrically arranged about the main skeleton, a plurality of branch skeletons are arranged at equal intervals from the tail end to the head end of the main skeleton, and the length of the branch skeleton gradually increases from the tail end to the head end of the main skeleton. The symmetrically arranged branch skeletons on the main skeleton are arranged at equal intervals and gradually increase in length from the tail end to the head end of the main skeleton, forming a distributed capacitance and inductance structure with a gradual change characteristic, greatly increasing the tortuosity and total length of the current path, thereby maximizing the equivalent electrical length of the structure in a limited physical space, significantly reducing the resonant frequency of the unit, and thereby realizing the high efficiency and miniaturization of the metasurface unit at a low frequency band (<1000 MHz). The length of the branch skeleton gradually increases from the tail end to the head end of the main skeleton, forming an impedance transition structure similar to a tapered line or a tapered structure. This gradual change characteristic helps to achieve better matching from the wave impedance of free space to the impedance of the unit structure, smoothens the current distribution, reduces energy reflection caused by impedance mutation, and thereby improves the operating bandwidth of the unit or reduces the return loss of the resonant point to some extent, and improves the energy reflection efficiency. The branch skeleton arranged at equal intervals and gradually increasing in length provides multiple controllable distribution paths and radiation nodes for the surface current on the main skeleton. By connecting the variable capacitance diode 400 (located between the tail end of the main skeleton and the center octagonal metal structure) at the key position of the structure, the distribution parameters can be more effectively utilized to adjust the resonant characteristics of the overall structure, increasing the sensitivity of the unit to the change in the capacitance value of the variable capacitance diode 400, so that a wider range of phase control capabilities can be obtained when the reflected phase is dynamically adjusted by direct current bias. The specific morphological design of the fishbone-shaped metal structure not only provides an electrical length extension in realizing low-frequency miniaturization, but also optimizes the bandwidth performance of the unit and the response sensitivity to adjustable devices by improving impedance matching and enhancing controllability of current distribution.

[0028] As Figure 1 and Figure 2As shown, in the embodiment, the varactor diodes 400 are located on the diagonals of the first layer of metal layer 101, and two varactor diodes 400 are arranged on each diagonal of the first layer of metal layer 101, a total of four varactor diodes 400. The four varactor diodes 400 are respectively located on two diagonals of the first layer of metal layer 101, and two are arranged on each diagonal, so that each pair of varactor diodes 400 located on the same diagonal can mainly affect the polarization response in a specific direction (for example, the varactor diodes 400 on one diagonal mainly regulate +45° polarization, that is, linear polarization along one diagonal, and the other mainly regulates -45° polarization, that is, linear polarization along the other diagonal). By independently controlling the bias voltage of the two groups of varactor diodes 400, the phase response of the two orthogonal polarization channels (±45° polarization) can be adjusted respectively and independently, which provides a key driving mechanism for realizing dual-polarization independent control, polarization rotation, and dynamic conversion between linear polarization and circular polarization; The varactor diodes 400 are accurately arranged on the diagonals and connected between the central octagonal metal structure and the peripheral fishbone-shaped metal structure. This position is a key node of the surface current distribution in the unit structure. By symmetrically changing the capacitance values of all varactor diodes 400, the symmetric resonant modes of the structure can be simultaneously tuned to achieve a wide range of reflection phase control. By asymmetrically changing the capacitance values of the varactor diodes 400 on different diagonals, the asymmetry of the structure can be intentionally introduced to excite specific asymmetric current modes, thereby effectively changing the polarization state of the reflected wave and realizing dynamic polarization control. The four varactor diodes 400 are completely symmetrically distributed on two diagonals. This highly symmetric arrangement ensures that the electromagnetic response of the unit has good consistency and repeatability when excited by electromagnetic waves with different polarization directions. At the same time, the symmetric layout makes the wiring of the direct current bias network also symmetric, reducing the additional phase error or performance deviation introduced by the asymmetry of the feed line, and ensuring the consistency of the tuning behavior of each unit in large-scale array applications.

[0029] As Figure 1 and Figure 2As shown, in the embodiment, the four fishbone-shaped metal structures and the octagonal metal structure are connected through the varactor diode 400, the negative electrode of the varactor diode 400 is welded on the octagonal metal structure, and the positive electrode of the varactor diode 400 is welded on the fishbone-shaped metal structure; by loading the varactor diode 400 on the angularly symmetrical fishbone-shaped metal structure, the adjustable metasurface unit not only has a low operating frequency band and a small size, but also can efficiently and dynamically control the phase and polarization of the reflected electromagnetic wave, realizing the joint control effect of multiple electromagnetic parameters. The negative electrode of the varactor diode 400 is welded on the central octagonal metal structure, and the positive electrode is welded on the peripheral fishbone-shaped metal structure, so that the varactor diode 400 is directly connected in series on the current main path between the core radiation structure and the external control structure of the unit. This connection mode directly and efficiently introduces the junction capacitance of the varactor diode 400 into the equivalent LC oscillation circuit that determines the resonant frequency of the unit, and significantly changes the equivalent impedance of the circuit by changing the bias voltage, thereby realizing sensitive and accurate dynamic control of the resonant frequency and phase response of the unit. Since the four varactor diodes 400 are connected in an angularly symmetrical manner between the central octagonal metal structure and the four fishbone-shaped metal structures, they physically form two pairs of orthogonal control channels. By independently controlling the bias voltage of the two varactor diodes 400 on each pair of diagonals, the electromagnetic response of the unit in two orthogonal polarization directions (polarized along two diagonals, i.e. ±45° polarization) can be adjusted. This independent controllability enables the unit to dynamically generate the required phase difference, thereby making it possible to flexibly change the polarization state of the reflected wave (such as linear polarization angle rotation or circular polarization generation), and ultimately achieving joint control of multiple electromagnetic parameters such as phase and polarization. The welding direction of the positive and negative electrodes of the varactor diode 400 and its connection relationship with the metal structure, together with the metal column, the feed layer and the patch inductor 500, form a complete DC bias path, ensuring that the DC control signal can be effectively applied to each varactor diode 400. At the same time, in combination with the RF element patch inductor 500 that isolates RF current, RF signal intrusion into the DC feed network can be effectively suppressed, reducing mutual interference and thereby ensuring the stability and reliability of the unit during wide-range tuning. This connection mode not only efficiently integrates the variable capacitance of the varactor diode 400 into the resonant circuit to achieve sensitive phase control, but also forms the basis for independent control of dual-polarization response, ultimately achieving the technical effects of low operating frequency band, small size and joint control of phase and polarization, and fundamentally solving the application limitations of the prior art such as high frequency band and single function.

[0030] As Figure 1 and Figure 2As shown, in the embodiment, five metal columns are provided, including one center column 301 located at the center position and four peripheral columns 302 located at the periphery of the center column 301; the center column 301 penetrates from the first metal layer 101 to the second metal layer 102 for grounding; the peripheral columns 302 penetrate from the first metal layer 101 to the fourth metal layer 104 for feeding; four circular holes 1021 are etched on the second metal layer 102, the circular holes 1021 are arranged one by one corresponding to the peripheral columns 302, and the peripheral columns 302 pass through the circular holes 1021 and isolate the second metal layer 102 from the peripheral columns 302. By providing the center grounding column (center column 301) and the four peripheral feeding columns (peripheral columns 302), independent and symmetrical direct current biasing paths are provided for the four varactor diodes 400; the center column 301 directly connects the first layer radiation structure (first metal layer 101) and the second layer metal floor (second metal layer 102), forming a stable common ground loop, ensuring the stability of the negative potential of the varactor diode 400; the four peripheral columns 302 penetrate to the fourth layer feeding layer (fourth metal layer 104), so that the direct current bias voltage can be independently applied to the anode of each varactor diode 400 from the bottom layer feeding network, so as to realize independent voltage control of each varactor diode 400, and then facilitate independent dual polarization regulation and control. Etching the circular holes corresponding to the peripheral feeding columns (peripheral columns 302) on the second metal layer 102 as the radio frequency ground makes the feeding columns pass through but keep electrical isolation, physically blocking the direct electrical connection between the direct current feeding column and the radio frequency ground, thereby effectively preventing the direct current control signal from interfering with the radio frequency ground potential, and also avoiding the leakage of radio frequency energy into the direct current control network through the feeding column, ensuring the purity of radio frequency performance and the stability of direct current control signal. The five metal columns are symmetrically distributed in the unit, not only as a path for electrical connection, but also play an important mechanical support role, enhancing the overall stability of the multi-layer stacked structure, and the symmetrical support and connection mode helps to reduce the misalignment between the layers, ensuring the consistency and repeatability of the electromagnetic performance of the unit, so as to facilitate the integration and application of large-scale arrays.

[0031] As Figure 1 and Figure 2As shown, in this embodiment, the third layer of metal layer 103 is a metal feed line that connects the first group of two diagonal peripheral pillars 302; the fourth layer of metal layer 104 is a metal feed line that connects the second group of two diagonal peripheral pillars 302, and then one metal pillar is selected from each of the two groups of diagonal metal pillars, and a patch inductor 500 is used to draw the feed line, which is used to connect the control circuit and avoid the flow of radio frequency current into the control power supply. The third layer of metal layer 103 and the fourth layer of metal layer 104 respectively connect the two peripheral pillars 302 arranged in diagonal lines, and each form an independent direct current feeding network, so that the two varactor diodes 400 located on the same diagonal line can be controlled by the same bias voltage at the same time, thereby forming two orthogonal and independent control channels (for example, controlling the linear polarization in two diagonal directions, i.e. ± 45° polarization), which provides a key circuit foundation for realizing independent and joint regulation of two orthogonal polarization states, and is the core guarantee for realizing complex polarization encoding (such as polarization rotation and circular polarization generation); The patch inductor 500 is welded on the feed line drawn from the fourth layer of metal layer 104, and the patch inductor 500 presents high impedance in the radio frequency band, which is equivalent to connecting a radio frequency choke coil in series in the direct current feeding path, effectively blocking the propagation path of the radio frequency current through the peripheral pillar 302 and the feed line to the direct current control power supply direction, preventing the leakage of radio frequency energy to the low-power direct current control circuit, avoiding the potential interference and even damage to the control circuit, and at the same time helping to maintain the stability of the super surface unit itself radio frequency performance; The direct current feeding networks respectively controlling the two diagonal lines are arranged in two different metal layers (the third layer of metal layer 103 and the fourth layer of metal layer 104), and are isolated by space. This vertical stacking wiring method maximizes the parallel wire length between the two groups of direct current feed lines, thereby reducing the electromagnetic coupling and crosstalk between the two control signals, ensuring the independence and accuracy of the control of the two polarization control channels.

[0032] As Figure 1 and Figure 2As shown, in this embodiment, the dielectric layer is a common printed circuit board, which adopts a microstrip PCB board with a dielectric constant interval of 1-10 and a magnetic permeability of 1; or the dielectric layer is a hard foam layer, and the foam is polystyrene foam. The polystyrene foam is used as the dielectric layer, which has a low material density and can effectively reduce the overall weight of the metasurface unit. At the same time, these materials are mature commercial materials, easy to obtain, and simple to process, which is conducive to reducing the manufacturing cost of the unit and facilitating large-scale production and array integration. The common printed circuit board adopts a material with a low dielectric constant (1-10) and a magnetic permeability of 1 (i.e., no magnetism), which can reduce the binding effect of the dielectric on the electromagnetic field and reduce the equivalent capacitance of the unit structure, thereby helping to expand the working bandwidth. In addition, the low dielectric constant makes the electromagnetic field more distributed in the air or the dielectric rather than concentrated on the surface of the metal structure, which enhances the sensitivity to the capacitance change of the varactor diode 400 and is conducive to obtaining a wider phase control range. The common PCB board has high mechanical strength and good temperature stability, which can ensure the flatness and reliability of the multi-layer stacked structure during processing and use. Although the polystyrene foam has low mechanical strength, it is extremely light and low in cost, which is suitable for application scenarios with stringent requirements on weight. The selection of these two materials provides a basic guarantee for the stable operation of the metasurface unit in different application environments.

[0033] As Figure 1 and Figure 2As shown, in the embodiment, four layers of dielectric layers are arranged, the first layer of dielectric layer 201 and the second layer of dielectric layer 202 are arranged between the first layer of metal layer 101 and the second layer of metal layer 102, the third layer of dielectric layer 203 is arranged between the second layer of metal layer 102 and the third layer of metal layer 103, and the fourth layer of dielectric layer 204 is arranged between the third layer of metal layer 103 and the fourth layer of metal layer 104. By arranging four independent dielectric layers, the four metal layers (radiation layer, ground layer, and feed layer) with different functions are effectively isolated, direct electrical short circuit between the metal layers is avoided, and the independence of the direct current bias network and the radio frequency ground network is ensured. At the same time, the dielectric layer provides a solid mechanical support for each metal layer, ensuring the integrity, flatness and stability of the multi-layer structure, which is crucial for ensuring the consistency of the unit performance in a large-scale array. The third layer of metal feed layer (the third layer of metal layer 103) and the fourth layer of metal feed layer (the fourth layer of metal layer 104) are isolated by a separate fourth layer of dielectric layer 204, providing layered wiring space for two independent direct current bias voltage channels (controlling the varactor diodes 400 on two diagonal lines, respectively), which maximizes the parallel wire length between the two direct current feed lines in the vertical direction, thereby reducing the electromagnetic coupling and crosstalk between the two control signals, and ensuring the independence and accuracy of the control of the two orthogonal polarization channels. The first layer of metal layer 101 and the second layer of metal layer 102 (i.e., the radiation layer and the ground layer) are arranged with two layers of dielectric (the first layer of dielectric layer 201 and the second layer of dielectric layer 202), which increases the equivalent distance between the radiation unit and the ground. By selecting the thickness and dielectric constant of the two layers of dielectric, the electromagnetic coupling strength between the radiation unit and the ground can be flexibly adjusted, thereby affecting the key radio frequency performance of the unit, such as the resonant frequency, impedance bandwidth, etc., providing design freedom for optimizing the low frequency response of the unit.

[0034] In this embodiment, the plate size of the dielectric layer is 90mm x 90mm, and the thickness size is 0.2mm-10mm. The plate size of the dielectric layer is set to 90mm x 90mm, which matches the size of the first layer metal layer 101 radiation structure, and together defines the physical boundary of a single metasurface unit; this size is much smaller than the size of the traditional low-frequency antenna unit, ensuring the miniaturization of the unit, and at the same time, the size forms a certain proportional relationship with the working wavelength (for example, below 1000MHz frequency band, wavelength greater than 300mm), which is one of the key geometric parameters to realize the required electromagnetic resonance (such as the resonance required for phase control) of the unit in the low frequency band; the thickness of the dielectric layer is set in the range of 0.2mm to 10mm, which can meet the processing technology requirements of the multi-layer metal structure stack, and a specific thickness selection (such as the thickness of the dielectric between the radiation layer and the ground layer) directly affects the equivalent capacitance and inductance value of the unit structure, and then affects its resonance frequency and impedance characteristics; in addition, sufficient interlayer thickness (such as between the third layer metal layer 103 and the fourth layer metal layer 104) provides the necessary space for the layout of the direct current feeding line, avoiding electrical short circuit or excessive coupling between different networks. The thickness range of 0.2mm to 10mm covers different needs from light and thin flexibility to rigid support, and selecting the appropriate thickness can control the overall thickness and weight of the unit as much as possible under the premise of ensuring that the multi-layer structure has sufficient mechanical strength and stability, so as to facilitate the large-scale array integration and deployment of the metasurface.

[0035] The application of the low-frequency polarized variable adjustable metasurface unit of this embodiment adopts the periodic arrangement of the above-mentioned low-frequency polarized variable adjustable metasurface unit to construct a low-frequency compact intelligent metasurface, and is used for emergency communication or tactical wireless communication.

[0036] In implementation, a low-frequency miniaturized polarized variable adjustable metasurface unit is provided, which is composed of four metal layers, four dielectric layers, five metal columns, four varactor diodes 400 and two patch inductors 500. The four varactor diodes 400 are symmetrically distributed on the diagonal line of the first layer metal layer 101, the second layer metal layer 102 is a metal ground plate, the third layer metal layer 103 and the fourth layer metal layer 104 are feeding structures, the two patch inductors 500 are located on the feeding line of the fourth layer metal layer 104, the four dielectric layers isolate the four metal layers, and the five metal columns pass through the dielectric layers to form a communication relationship between different metal layers. The adjustable metasurface unit provided by the present application works near 600MHz, the size is less than 0.2 wavelength, the reflection efficiency of electromagnetic waves is more than 70%, and the polarization and phase of the reflected electromagnetic waves can be adjusted.

[0037] More specifically, by loading varactor diodes 400 on the angularly symmetric fishbone-shaped metal structures, the tunable metasurface unit can not only work in a low frequency band (less than 1000 MHz) and have a small size, but also efficiently dynamically control the phase and polarization of the reflected electromagnetic waves, realizing the joint control effect of multiple electromagnetic parameters.

[0038] The first layer of metal 101 in the four layers of metal is angularly symmetrically arranged around the octagonal metal structure by four fishbone-shaped metal structures, which is used to adjust the phase and polarization of the reflected electromagnetic waves; the second layer of metal 102 is a metal floor containing vias (for non-contact passing of the peripheral column 302), which is used to reflect electromagnetic waves; the third layer of metal 103 and the fourth layer of metal 104 are metal feed lines, which are used for feeding of the varactor diodes 400; the four layers of dielectric are foam or ordinary printed circuit boards; the five metal columns are conductive metal columns (feed columns), which are used to connect structures between different metal layers; the four varactor diodes 400 are located on the diagonal lines of the first layer of metal 101, and are simultaneously located between the four fishbone-shaped metal structures and the octagonal metal structure of the first layer of metal 101, which are used to change the phase of the reflected electromagnetic waves; the two patch inductors 500 are located on the fourth layer of metal 104, which are used to isolate radio frequency currents.

[0039] In some embodiments, the first layer of metal 101 is angularly symmetrically arranged around the octagonal metal structure by four fishbone-shaped metal structures, forming a square profile structure, and the four fishbone-shaped metal structures and the octagonal metal structure are connected by varactor diodes 400.

[0040] In some embodiments, the second layer of metal 102 is a metal floor for reflecting electromagnetic waves, and four circular holes are etched on the metal floor for isolating metal columns; the third layer of metal 103 is a metal feed line connecting the first pair of diagonal metal columns; the fourth layer of metal 104 is a metal feed line connecting the second pair of diagonal metal columns, and one metal column is selected from each of the latter two pairs of diagonal metal columns to lead out the feed line for connecting the control circuit.

[0041] In some embodiments, the four layers of dielectric are foam or ordinary printed circuit boards, the size of the four layers of dielectric is 90mm x 90mm, the thickness is in the interval 0.2mm-10mm, the foam is polystyrene foam, and the ordinary printed circuit board is a microstrip PCB board with a dielectric constant in the interval 1-10 and a magnetic permeability of 1.

[0042] In some embodiments, the five metal columns are conductive metal columns (feed columns), and the metal column at the center of the structure penetrates from the first layer of metal 101 to the second layer of metal 102 for grounding, and the remaining four metal columns penetrate from the first layer of metal 101 to the fourth layer of metal 104 for feeding.

[0043] In some embodiments, four varactor diodes 400 are located on the diagonal of the first layer of metal layer 101, and are interposed between the four fishbone-shaped metal structures and the octagonal metal structure of the first layer of metal layer 101, for changing the phase of the reflected electromagnetic wave; two patch inductors 500 are located on the metal feed line of the fourth layer of metal layer 104, for blocking the radio frequency current.

[0044] The low-frequency miniaturized variable polarization adjustable metasurface unit has the following advantages: compared with the conventional adjustable metasurface unit, the low-frequency miniaturized variable polarization adjustable metasurface unit has a size of less than 0.2 wavelengths (calculated at a center frequency of 600 MHz), high reflection efficiency (a reflection rate of higher than 70% near 600 MHz), 2-bit phase control effect on reflected electromagnetic waves, and polarization of the reflected electromagnetic waves that can be controlled from linear polarization to orthogonal polarization and circular polarization. The low-frequency miniaturized variable polarization adjustable metasurface unit has a small size, high efficiency, simple processing, good performance, and wide application prospects in low-frequency wireless communication.

[0045] As shown in Figure 2 The adjustable metasurface unit is composed of four layers of metal layers, four layers of dielectric layers, five metal columns, four varactor diodes 400, and two patch inductors 500. The four layers of metal layers are a first layer of metal layer 101, a second layer of metal layer 102, a third layer of metal layer 103, and a fourth layer of metal layer 104, and the thickness of the metal layers is 0.036 mm. The dielectric layer has a size of 90 mm x 90 mm, a thickness of 0.5 mm to 10 mm, and a relative dielectric constant of 1 to 10. The dielectric layer is foam or a general printed circuit board, and the magnetic permeability is 1. The metal column has a diameter of 1 mm, and the metal column at the center of the unit structure penetrates through the first layer of metal layer 101 to the second layer of metal layer 102, and the other four metal columns penetrate through the first layer of metal layer 101 to the fourth layer of metal layer 104. In addition, the four varactor diodes 400 are located on the first layer of metal layer 101, and the two patch inductors 500 are located on the fourth layer of metal layer 104.

[0046] As shown in Figure 2 The first layer of metal layer 101 is the core structure of the adjustable metasurface unit, which is composed of four fishbone-shaped metal structures arranged in angular symmetry around an octagonal metal structure, forming a square outline structure, and the four fishbone-shaped metal structures and the octagonal metal structure are connected by four varactor diodes 400. Figure 1As shown by the black square in (a). The four varactor diodes 400 are located diagonally on the first metal layer 101. The positive terminals of the varactor diodes 400 are all soldered to a herringbone-shaped metal structure. A feed metal pillar is soldered to the center of the tail of two adjacent herringbone-shaped metal structures, extending to the fourth metal layer 104, and finally connected to the control power supply through the feed line of the fourth metal layer 104. The negative terminals of the varactor diodes 400 are all soldered to an octagonal metal structure. A metal pillar is soldered to the center of the octagonal metal structure, and the other end of the metal pillar is soldered to the second metal layer 102. The second metal layer 102 is a metal ground plane, as shown... Figure 2 As shown in (b), corresponding Figure 2 The second metal layer 102 is connected to the negative terminal of the varactor diode 400 and to the ground wire of the control power supply to form a reference voltage, typically 0V. Additionally, to prevent the varactor diode 400 from being short-circuited, in... Figure 1 In (b), on the second metal layer 102, the metal around the four feed metal pillars is etched away to prevent the metal ground plane from contacting the four feed metal pillars. The third metal layer 103 is the feed wire, such as... Figure 2 As shown in (c), corresponding Figure 1 The third metal layer 103 is simply a 1mm wide metal connecting line connecting the first pair of diagonally opposite feed metal pillars. The fourth metal layer 104 is the feed layer, as shown below. Figure 2 As shown in (d), corresponding Figure 2 The fourth metal layer 104 first connects the remaining second pair of diagonal metal pillars via a pair of 1mm wide metal connecting lines, ensuring that the control voltage of each pair of diagonal varactor diodes 400 is completely consistent. Then, one metal pillar from each of the two sets of diagonal metal pillars is selected to lead out a feed line, and both feed lines are ultimately connected to the control power supply. To prevent RF current from flowing into the control power supply, in... Figure 2 (d) On each of the two feed lines, a 500mm surface mount inductor is soldered. Figure 3 As shown by the black square in (d), the inductance of the surface mount inductor 500 is 22uH.

[0047] pass Figure 3 As can be seen from the unit feeding mode, the control voltage of each pair of diagonal varactor diodes 400 in the adjustable metasurface unit is consistent.

[0048] Phase control process when non-polarization conversion: connect two pairs of diagonal varactor diodes 400 to the same control voltage, at this time the states of the four varactor diodes 400 are completely consistent, and since the unit is completely symmetrical in the horizontal and vertical directions, the electromagnetic characteristics of the unit under horizontal polarization (x polarization) and vertical polarization (y polarization) wave illumination are completely consistent, and the unit does not have the function of polarization conversion. Based on this, the unit is irradiated with a horizontally polarized (x polarized) wave, and the electromagnetic simulation of the unit is performed, and the control voltage of the varactor diode 400 is adjusted to adjust the capacitance value of the varactor diode 400 to achieve phase regulation of the reflected wave. Four typical capacitance values C1, C2, C3, C4 are selected, with a value range of 2pF-10pF, so that the reflection phase of the adjustable metasurface unit at 600MHz decreases by 90 degrees, forming a 2-bit phase control effect. Figure 3 (a) and Figure 3 (b) are the reflectivity and reflection phase curves of the adjustable metasurface unit corresponding to the selected four capacitance values, respectively, wherein C1, C2, C3, C4 capacitance values correspond to curves 00, 01, 10, 11, respectively. It can be seen that the reflectivity of the adjustable metasurface unit is always maintained above 70% near 600MHz, while the change range of the reflection phase covers 270 degrees, and the phase interval of every two curves is 90 degrees, forming a 2-bit phase modulation effect on the reflected wave near 600MHz.

[0049] Phase control process when orthogonal polarization conversion: Since the states of each pair of diagonal varactor diodes 400 are consistent, the capacitance values of the four varactor diodes 400 have only two variables. Connect the two groups of diagonal varactor diodes 400 to different control voltages, so that the capacitance values of the two pairs of diagonal varactor diodes 400 are (C1, C3), (C2, C4), (C3, C1), and (C4, C2), respectively. At this time, the performance curves obtained by simulation are numbered 00, 01, 10, and 11. Set the horizontally polarized (x polarized) wave to irradiate, Figure 3 (c) and Figure 3 (d) are the reflectivity and reflection phase curves of the orthogonal polarization reflected wave of the adjustable metasurface unit corresponding to the selected four groups of capacitance values. It can be seen that under the condition of orthogonal polarization conversion, the designed adjustable metasurface unit can still maintain a reflectivity of more than 70% and a 2-bit phase control effect near 600MHz.

[0050] Phase control process when linear polarization to circular polarization conversion: connect two pairs of diagonal varactor diodes 400 to different control voltages, so that the capacitance values of the two groups of diagonal varactor diodes 400 are (C1, C2), (C2, C3), (C3, C4), and (C4, C1), respectively. At this time, the performance curves obtained by simulation are numbered 00, 01, 10, and 11. Set the horizontally polarized (x polarized) wave to irradiate, ​(e) and ​ (f) are the reflectivity and reflection phase curves of the circularly polarized reflected wave corresponding to the four groups of capacitance values respectively.

[0051] In summary, the low-frequency miniaturized polarization conversion tunable metasurface unit of the present application not only realizes miniaturized design (less than 0.2 wavelength) in the low-frequency band (around 600MHz), but also realizes efficient (reflectivity higher than 70%) electromagnetic wave phase and polarization control effect. The low-frequency miniaturized polarization conversion tunable metasurface unit of the present application can be constructed into a low-frequency compact intelligent metasurface by periodic arrangement, and has wide application prospect in the field of low-frequency communication such as emergency communication, tactical wireless communication, etc.

[0052] The remaining matters of the present application are known technologies.

[0053] The technical features of the above embodiments can be combined arbitrarily, and in order to make the description simple, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0054] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the protection scope of the present application.

[0055] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A low-band metapolarizable tunable metasurface unit, characterized in that, The application relates to a metal layer, a dielectric layer, a metal column, a varactor diode (400) and a patch inductor (500), four layers of the metal layer are arranged in sequence along the thickness direction, and the adjacent two layers of metal layers are isolated by the dielectric layer; The first layer of metal layers (101) comprises a first metal structure (1011) and a second metal structure (1012) and is used for controlling the phase and polarization of reflected electromagnetic waves; The varactor diode (400) is arranged between the first metal structure (1011) and the second metal structure (1012) and is used for changing the phase of reflected electromagnetic waves; The second layer of metal layers (102) is a metal floor and is used for reflecting electromagnetic waves; The third layer of metal layers (103) and the fourth layer of metal layers (104) are both feed layers; The metal column is a feed column and is used for connecting different metal layers; The patch inductor (500) is located on the fourth layer of metal layers (104) and is used for cutting off radio frequency current.

2. The low-band varactor metasurface unit of claim 1, wherein, The first metal structure (1011) is arranged at the middle of the first layer of metal layers (101) and is an octagonal metal structure; The second metal structure (1012) comprises four fishbone-shaped metal structures, the tail ends of the fishbone-shaped metal structures are arranged perpendicularly to the edge strips of the octagonal metal structure, one fishbone-shaped metal structure is arranged on the octagonal metal structure at an interval of one edge strip, and the head ends of the four fishbone-shaped metal structures are arranged in sequence and form a square contour structure.

3. The low-band varactor metasurface unit of claim 2, wherein, The varactor diode (400) is located on the diagonal lines of the first layer of metal layers (101), two varactor diodes (400) are arranged on each diagonal line of the first layer of metal layers (101), and a total of four varactor diodes (400) are arranged.

4. The low-band metapolarizable metasurface unit of claim 3, wherein, The four fishbone-shaped metal structures and the octagonal metal structure are connected through the varactor diode (400), the negative electrode of the varactor diode (400) is welded on the octagonal metal structure, and the positive electrode of the varactor diode (400) is welded on the fishbone-shaped metal structure; by loading the varactor diode (400) on the angularly symmetrical fishbone-shaped metal structure, the adjustable metasurface unit not only has low working frequency and small size, but also can efficiently and dynamically control the phase and polarization of reflected electromagnetic waves, and realizes the joint control effect of multiple electromagnetic parameters.

5. The low-band metapolarizable metasurface unit of any one of claims 1 to 4, wherein, The metal column is provided with five metal columns, including a center column (301) located at the center position and four peripheral columns (302) located outside the center column (301); The center column (301) penetrates through the first layer of metal layers (101) to the second layer of metal layers (102) and is used for grounding; The peripheral column (302) penetrates through the first layer of metal layers (101) to the fourth layer of metal layers (104) and is used for feeding; Four circular holes (1021) are etched on the second layer of metal layers (102), the circular holes (1021) are arranged in one-to-one correspondence with the peripheral columns (302), the peripheral columns (302) pass through the circular holes (1021) and isolate the second layer of metal layers (102) from the peripheral columns (302).

6. The low-band varactor metasurface unit of claim 5, wherein, The third layer of metal layers (103) is a metal feed line and connects the first group of two peripheral columns (302) arranged diagonally. The fourth layer metal layer (104) is a metal feed line, which firstly connects the second group of two diagonal outer columns (302), then selects one metal column in the first group of two diagonal outer columns (302) and one metal column in the second group of two diagonal outer columns (302) to draw out the feed line, and welds a patch inductor (500) on the feed line, which is used for connecting the control circuit and avoiding the radio frequency current flowing into the control power supply.

7. The low-band metapolarizable metasurface unit of any one of claims 1 to 4, wherein, The dielectric layer is a common printed circuit board, and the common printed circuit board adopts a microstrip PCB board with a dielectric constant interval of 1-10 and a magnetic permeability of 1. The dielectric layer is a hard foam layer, and the foam is polystyrene foam.

8. The low-band metapolarizable metasurface unit of claim 7, wherein, The dielectric layer is provided with four layers, the first layer dielectric layer (201) and the second layer dielectric layer (202) are arranged between the first layer metal layer (101) and the second layer metal layer (102), the third layer dielectric layer (203) is arranged between the second layer metal layer (102) and the third layer metal layer (103), and the fourth layer dielectric layer (204) is arranged between the third layer metal layer (103) and the fourth layer metal layer (104).

9. The low-band metapolarizable metasurface unit of claim 8, wherein, The dielectric layer has a plate size of 90mmx90mm and a thickness size of 0.2mm-10mm.

10. Use of a low-band metasurface unit of variable polarization, characterized in that, The low-frequency variable polarization adjustable metasurface unit periodical arrangement of any one of claims 1-9 is used to construct a low-frequency compact intelligent metasurface for emergency communication or tactical wireless communication.

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