CN113991312A - Dual-polarized 3bit phase independent adjustable reconfigurable intelligent super-surface unit - Google Patents
Dual-polarized 3bit phase independent adjustable reconfigurable intelligent super-surface unit Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/0086—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
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- H01Q1/48—Earthing means; Earth screens; Counterpoises
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/50—Structural association of antennas with earthing switches, lead-in devices or lightning protectors
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- H—ELECTRICITY
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- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
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- H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
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Abstract
The invention discloses a reconfigurable intelligent super-surface unit with independently adjustable dual-polarization 3bit phases, which is of a four-layer structure, wherein a second layer and a third layer are feed layers, and the fourth layer is a metal ground; the first layer comprises four isosceles right triangle metal patches and four cross-shaped metal patches, and each isosceles right triangle is connected with the corresponding cross-shaped metal patch through a varactor; the four isosceles right triangle metal patches are respectively connected with one metal via hole, the x-axis direction metal via hole is connected with the second layer feed layer, and the y-axis direction metal via hole is connected with the third layer feed layer. By adjusting the voltages at two ends of the varactor in two orthogonal polarization directions, the unit realizes 3bit phase modulation within an oblique incidence range of 0-45 degrees in the two orthogonal polarization directions independently, so that the unit realizes a beam scanning function in the two polarization directions in a decoupling manner and is insensitive to an electromagnetic wave incidence angle.
Description
Technical Field
The invention relates to a reconfigurable intelligent super-surface unit.
Background
With the continuous development of wireless communication technology, the information transmission speed of the network reaches a new peak, but the problem also comes to the end. For example, 5G signals are less permeable and have greater energy loss than 4G signals. It is now common to build Ultra Dense Networks (UDNs) to improve system throughput by deploying more dense Base Stations (BSs) or Access Points (APs), but this is accompanied by higher cost and power consumption, and the dense base stations also aggravate network interference. Therefore, it is imperative to find an efficient, reliable, and low-cost signal transmission scheme.
In this context, Reconfigurable Intelligent Surfaces (RIS) are considered as a promising technology. Generally speaking, the propagation process between the transmission of a signal via a transmitter to the reception of a receiver is uncontrollable and random, but the advent of RIS technology has changed this situation. Since the RIS can adjust the state of each unit to control the reflected electromagnetic waves, an intelligent electromagnetic environment is formed. This reduces the complex reflections and diffractions caused by obstacles during signal propagation, which in turn makes the signal propagation controllable to some extent. Compared with the traditional wireless relay, the RIS can realize a full-duplex transmission mode without introducing self-interference, has the characteristics of low cost, light weight, low energy consumption and the like, and generates wide application in wireless communication based on the characteristic, such as reducing the multipath effect of a wireless channel, improving the wireless communication safety, channel estimation and the like.
The main hardware part of the RIS is based on the concept of a super surface, specifically, the super surface is an artificial electromagnetic material, the surface is composed of a large number of low-cost sub-wavelength metal and medium units, the active super surface is further provided with active units such as pin diodes, varactors, MEMS switches and the like on each unit, the amplitude or phase of electromagnetic waves reflected on the RIS can be changed according to actual requirements by adjusting the states of the active units, the purpose of beam forming can be achieved by adjusting the reflection coefficients of the units according to a certain rule, and finally the original static communication environment becomes dynamic and controllable.
In order to increase the coverage, most mobile communication base stations use dual-polarized transmitting antennas to improve the performance, which requires the RIS to be dual-polarized, otherwise, polarization loss occurs when the polarization direction of the RIS is not consistent with the polarization direction of the incoming wave, i.e., only one polarized signal can be received, in addition, the polarization of the RIS can also affect the receiving of the user's receiving antenna to the reflected wave, if the RIS and the user's receiving antenna are single-polarized, the signal can be received to the maximum extent only when the polarization directions of the receiving antenna and the RIS are consistent, otherwise, the received signal energy will be greatly reduced, or even the received signal energy can not be received when the polarization directions are orthogonal. Secondly, the oblique incidence stability of the RIS is also crucial, when an incident wave is not vertical incidence, because spatial dispersion often exists inside the RIS unit, the phase response of the RIS unit is extremely sensitive to the incident angle of an incoming wave, and if the problem is not solved, the encoding of the RIS under normal incidence cannot correctly control a reflected beam under oblique incidence. In addition, the number of bits with adjustable phases determines the performance of the RIS, and the higher the number of bits is, the finer the control of the RIS on the electromagnetic waves is. Currently, no RIS unit design capable of simultaneously satisfying the above points appears, which undoubtedly restricts the further application of RIS in communication systems.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the prior art, a reconfigurable intelligent super-surface unit insensitive to an incident angle and independently adjustable in dual-polarization 3bit phase is provided.
The technical scheme is as follows: the reconfigurable intelligent super-surface unit with the dual-polarization 3-bit phase independently adjustable comprises four layers of functional structures, wherein a second layer and a third layer are feed layers, and a fourth layer is a metal ground; the upper surface of the unit is a first layer, the lower surface of the unit is a fourth layer, the upper surface and the lower surface of the unit are both square, and the side lengths are equal, namely the side length of the unit; the first layer comprises four isosceles right triangle metal patches and four cross-shaped metal patches, and each isosceles right triangle is connected with a corresponding cross-shaped metal patch through a varactor; the four isosceles right triangle metal patches are respectively connected with one metal through hole, two metal through holes in the x-axis direction are connected with the second layer of feed layer, and two metal through holes in the y-axis direction are connected with the third layer of feed layer; by adjusting the voltages at two ends of the varactor in two orthogonal polarization directions, the unit realizes 3bit phase modulation within an oblique incidence range of 0-45 degrees in the two orthogonal polarization directions independently, so that the unit realizes beam scanning functions in the two polarization directions in a decoupling manner and is insensitive to electromagnetic wave incidence angles.
Furthermore, the first layer comprises a square metal patch and a square ring metal patch, the square metal patch is positioned in the center of the first layer and is positioned inside the square ring metal patch, and the diagonal line of the square metal patch is superposed with the diagonal line of the square ring metal patch; the first layer also comprises four rectangular metal patches, and each edge of the square-ring metal patch is vertically crossed with one rectangular metal patch to form a cross-shaped structure; dividing the square metal patch and the square ring metal patch along the diagonal line by using a gap, dividing the square metal patch along the diagonal line to form four isosceles right triangle metal patches, and dividing the square metal patch along the diagonal line to form four cross metal patches; each isosceles right triangle metal patch is connected with the nearest cross metal patch by a varactor.
Furthermore, a square annular metal strip serving as a grounding wire is attached to the periphery of the first layer, and the side length of the square annular metal strip is the unit side length; each side of the square annular metal strip is directly connected with one side of the rectangular metal patch in the cross-shaped metal patch.
Further, a rectangular coordinate system is set by taking the first layer as a reference, one side of the square metal patch is taken as the x-axis direction, and the other side of the square metal patch, which is vertical to the x-axis, is taken as the y-axis direction; the second layer is a first square metal feed layer, the side of the first square metal feed layer is parallel to the corresponding side of the square annular metal strip, and the side length is smaller than that of the square annular metal strip; a first metal strip and a second metal strip are respectively arranged on the edge of the first square metal feed layer in the positive and negative directions of the y axis and are used for connecting the square annular metal strips; the third layer is a second square metal feed layer, the side of the second square metal feed layer is parallel to the corresponding side of the square annular metal strip, and the side length is smaller than that of the square annular metal strip; the side lengths of the second square metal feed layer and the first square metal feed layer are equal; and a third metal strip and a fourth metal strip are respectively arranged on the edge of the second square metal feed layer in the positive and negative directions of the x axis and are used for connecting the square annular metal strips.
Furthermore, the fourth layer is a square metal ground, the side of the square metal ground is parallel to the corresponding side of the square annular metal strip, and the side length is equal to the unit side length, namely, each side of the square metal ground is directly connected with the square annular metal strip.
Furthermore, in the x-axis direction and the y-axis direction of the first layer, four isosceles right triangle metal patches are respectively connected with one metal via hole, and the metal via holes are perpendicular to the plane of the first layer and penetrate through the second layer, the third layer and the fourth layer; the two metal through holes in the x-axis direction are connected with the first square metal feed layer of the second layer, and the two metal through holes in the x-axis direction are not connected with the second square metal feed layer of the third layer; the two metal through holes in the y-axis direction are connected with the second square metal feed layer of the third layer, and the two metal through holes in the y-axis direction are not connected with the first square metal feed layer of the second layer; the four metal via holes are not connected with the square metal ground of the fourth layer.
Further, the first dielectric layer between the first layer and the second layer has a relative dielectric constant εr2.65, polytetrafluoroethylene F4B with a loss tangent tan δ of 0.001; the relative dielectric constant of the second dielectric layer between the second layer and the third layer is epsilonr3.7 Rogers RO4450 prepreg with loss tangent tan δ of 0.004; the relative dielectric constant of the third dielectric layer between the third layer and the fourth layer is epsilonrPolytetrafluoroethylene F4B having a loss tangent tan δ of 0.001 was used as 2.65.
Further, the varactor is of the type SMV 1405; when a voltage of 11v is applied to the two sides of the varactor, the equivalent RLC model is that a resistor of 0.36 omega, an inductor of 0.7nH and a capacitor of 0.76pF are connected in series.
Has the advantages that: (1) a pair of variable capacitance tubes is integrated on each unit in the x-axis direction and the y-axis direction respectively, and independent 3-bit phase modulation can be realized in the x-axis direction and the y-axis direction by controlling the two pairs of variable capacitance tubes respectively through direct current feed. (2) The invention can keep higher energy efficiency when the continuous phase change range is larger than 315 degrees by optimizing the unit structure and introducing the low-loss variable capacitance tube. (3) The invention reduces the mutual coupling between the units by reducing the electric size of the units and introducing a mushroom-type EBG feed structure, and can still maintain stable phase response and larger reflected wave amplitude under the oblique incidence of TE and TM polarized electromagnetic waves.
Drawings
FIG. 1 is a schematic structural diagram of a reconfigurable intelligent super-surface unit of the present invention;
FIG. 2 is a schematic diagram of the interlayer dimensions of the reconfigurable intelligent super-surface element of the present invention;
FIG. 3 is a schematic diagram of a first level architecture of a reconfigurable intelligent super-surface unit of the present invention;
FIG. 4 is a schematic diagram of a second layer structure of the reconfigurable intelligent super-surface unit of the present invention;
FIG. 5 is a third level schematic structural view of a reconfigurable intelligent super-surface unit of the present invention;
FIG. 6 is a schematic diagram of a fourth layer structure of a reconfigurable intelligent super-surface unit of the present invention;
FIG. 7 is a surface current plot along the x-axis polarization direction for a reconfigurable intelligent super-surface unit of the present invention;
FIG. 8 is a surface current plot along the y-axis polarization direction for a reconfigurable intelligent super-surface unit of the present invention;
FIG. 9 is a cross-polarization amplitude diagram of a reconfigurable intelligent super-surface unit of the present invention;
FIG. 10 is a reflected wave amplitude diagram of 8 encoding states of the reconfigurable intelligent super-surface unit under x-axis and y-axis polarization respectively;
FIG. 11 is a reflected wave phase diagram of the reconfigurable intelligent super-surface unit of the invention in 8 encoding states under x-axis and y-axis polarization respectively;
FIG. 12 is a reflected wave amplitude diagram for State 4 at oblique incidence for a reconfigurable intelligent super-surface unit of the present invention;
FIG. 13 is a reflected wave phase diagram for State 4 at oblique incidence for the reconfigurable intelligent super-surface unit of the present invention;
FIG. 14 shows the results of beam scanning in the x-axis direction after the array of smart meta-surface elements is reconfigured in accordance with the present invention;
FIG. 15 shows the beam scanning results in the y-axis direction after the array of smart meta-surface elements is reconfigured in accordance with the present invention;
fig. 16 is a 0 ° outgoing directional diagram after the reconfigurable intelligent super-surface cell array according to the invention is obliquely incident at 40 ° in the x-axis direction.
Detailed Description
The invention is further explained below with reference to the drawings.
A reconfigurable intelligent super-surface unit insensitive to an incident angle and capable of independently adjusting a dual-polarized 3bit phase adopts a unit resonance structure shown in figures 1 and 2 in order to realize independent adjustment and control of electromagnetic waves under orthogonal polarized incident waves. The unit comprises four functional structures, namely a first layer, a second layer, a third layer and a fourth layer, wherein dielectric layers are arranged among the layers. The upper surface of the unit is a first layer, the lower surface of the unit is a fourth layer, the upper surface and the lower surface of the unit are both square, and the side lengths are equal, namely the side length p of the unit.
As shown in fig. 3, the first layer comprises a side length l1Square metal patch and an outer side length l2Width of w2The square metal patch is located in the center of the first layer and inside the square metal patch, and the diagonal of the square metal patch coincides with the diagonal of the square metal patch. The first layer further comprises four layers having a width w1Each side of the square ring metal patch is vertically crossed with one rectangular metal patch to form a cross structure. Along the diagonal with a width g2The gap of (2) separates square metal patches and square ring metal patches, divides the square metal patches into four isosceles right triangle metal patches along the diagonal line, and divides the square metal patches into four cross metal patches along the diagonal line. The distance between each isosceles right triangle metal patch and the nearest cross metal patch is g1Connected by varactors, four in totalA varactor.
As shown in fig. 1 and 2, a square annular metal strip serving as a ground line is further attached to the periphery of the first layer, and the outer side of the square annular metal strip is p, and the width of the square annular metal strip is t; each side of the square annular metal strip is directly connected with one side of the rectangular metal patch in the cross-shaped metal patch.
And setting a rectangular coordinate system by taking the first layer as a reference, and taking one side of the square metal patch as the x-axis direction, and taking the other side perpendicular to the x-axis in the square metal patch as the y-axis direction.
As shown in FIG. 4, the second layer is a first square metal feed layer, the side of the first square metal feed layer is parallel to the corresponding side of the square annular metal strip, and the side length is l3. The edge of the first square metal feed layer is respectively provided with a length l in the positive and negative directions of the y axis4Width of w3For connecting the square metal feed layer. In the middle of the first square metal feed layer, two semi-axes with radius r are respectively arranged on the positive half shaft and the negative half shaft of the y-axis1The circular hole of (2).
As shown in fig. 5, the third layer is a second square metal feed layer, the side of the second square metal feed layer is parallel to the corresponding side of the square annular metal strip, and the side length is l3(ii) a The second square metal feed layer and the first square metal feed layer are equal in side length. The edge of the second square metal feed layer is respectively provided with a length l in the positive and negative directions of the x axis4Width of w3For connecting the square metal feed layer. In the middle of the first square metal feed layer, there are two circular holes with radius r1 on the positive and negative half-axes of the x-axis.
As shown in fig. 6, the fourth layer is a square metal ground, the side of the square metal ground is parallel to the corresponding side of the square ring-shaped metal strip, and the side length is p. The middle of the square metal ground is provided with 4 positive and negative half shafts with the radius r on the x axis and the y axis respectively1Round hole of
The first dielectric layer between the first layer and the second layer has a thickness h1Has a relative dielectric constant of ∈r2.65 and a loss tangent tan δ of 0.001, in polytetrafluoroethylene F4B. The second dielectric layer between the second layer and the third layer has a thickness h2Has a relative dielectric constant of ∈r3.7 and a loss tangent tan δ of 0.004. The third dielectric layer between the third layer and the fourth layer adopts the thickness h3Has a relative dielectric constant of ∈r2.65 and a loss tangent tan δ of 0.001, in polytetrafluoroethylene F4B.
In the x-axis direction and the y-axis direction of the first layer, four isosceles right triangle metal patches are respectively connected with one metal patch with the radius of r2The metal via holes are connected, are vertical to the plane of the first layer and penetrate through the second layer, the third layer and the fourth layer. The two metal through holes in the x-axis direction penetrate through the two round holes of the second square metal feed layer in the third layer and are not connected with the two round holes; the two metal through holes in the y-axis direction are connected with the second square metal feed layer of the third layer, and the two metal through holes in the y-axis direction penetrate through the two round holes of the first square metal feed layer of the second layer and are not connected with the two round holes; the four metal vias pass through and are not connected to the 4 circular holes of the square metal ground of the fourth layer.
In the unit structure, the feed voltage of the varactor in the x-axis direction and the y-axis direction is respectively adjusted through the first metal strip, the second metal strip, the third metal strip and the fourth metal strip, so that the capacitance value of the varactor is continuously changed, and the resonant frequency in the x-axis direction and the resonant frequency in the y-axis direction are independently regulated and controlled.
In this embodiment, the varactor is of the type SMV 1405; when 11v of voltage is applied to two sides of the varactor, the equivalent RLC model is formed by connecting a resistor of 0.36 omega, an inductor of 0.7nH and a capacitor of 0.76pF in series, the dual-polarized independent adjustable unit realizes decoupling between polarizations, and the units independently perform phase regulation and control in two polarization directions respectively. When the capacitance value of the varactor changes continuously, the dual-polarized unit has 8 phase coding states with the phase interval of about 45 degrees, and then 3bit coding is realized.
The double-layer feed structures of the second layer and the third layer are used for feeding the varactor in the polarization directions of the x axis and the y axis respectively; the first square metal feed layer of the second layer is connected with the second metal strip through the first metal strip in the y-axis direction, the metal strips are equivalent to inductance and are isolated from alternating current and direct current, and the RIS unit is controlled in the y-axis direction due to the fact that the first square metal feed layer is simultaneously connected with two metal through holes in the x-axis direction to form a phase gradient in the x-axis direction so as to achieve beam scanning in the x-axis direction; the second square metal feed layer of the third layer is connected with the fourth metal strip through the third metal strip in the x-axis direction, the metal strips are equivalent to inductance and are isolated from alternating current and direct current, and the second square metal feed layer is also connected with the two metal through holes in the y-axis direction at the same time, so that the RIS unit is controlled in the x-axis direction to form a phase gradient in the y-axis direction, and beam scanning in the y-axis direction is realized. The amplitude of the RIS unit is only changed in size without frequency deviation when the RIS unit is obliquely incident, so that the phase difference is small, and the angle stability of the RIS unit under TE and TM polarized oblique incidence is improved.
In fig. 1 to 6, the structural parameters of the dual-polarized 3-bit phase-independent adjustable reconfigurable intelligent super-surface unit insensitive to the incident angle are determined in table 1.
TABLE 1
Through adjusting the feed voltage of the varactor in the directions of the x axis and the y axis, the capacitance value of the varactor is continuously changed, and the resonant frequency of the equivalent resonant cavity in the directions of the x axis and the y axis is independently regulated and controlled. The equivalent reactance of the dual-polarization 3-bit phase-independent adjustable reconfigurable intelligent super-surface unit insensitive to the incident angle is determined by the characteristics of the varactor, so that a proper varactor needs to be selected to meet the design requirement. Finally, varactor SMV1405 from Skyworks corporation was selected for its high Q, low series resistance, low phase noise, and other advantages. When a reverse bias of 0-30V is applied across the capacitor, the parasitic inductance and resistance are stabilized at 0.7nH and 0.36 Ω, and the capacitance changes from 1.74pF to 0.58 pF.
The main technical difficulty of the dual-polarized 3-bit phase-independent adjustable RIS unit is decoupling between polarizations, namely when the states of the first varactor and the second varactor in the x polarization direction are changed, the amplitude phase of a reflected wave in the y polarization direction is not influenced, and vice versa. To further illustrate this, the operating mode of its individual polarization is full-wave simulated in the electromagnetic simulation software CST. When a voltage of 11v is applied to two sides of the varactor, the equivalent RLC model is that a resistance of 0.36 Ω, an inductance of 0.7nH and a capacitance of 0.76pF are connected in series, and by analyzing the surface current diagrams, as can be seen from fig. 7 and 8, when an electric field is polarized and distributed along the x-axis direction, the surface current is mainly distributed on copper sheets on two sides of the varactor along the x-axis direction, and almost no surface current is distributed on two sides of the varactor along the y-axis direction, and a similar conclusion can be obtained when the electric field is polarized and distributed along the y-axis direction. This shows that the varactors are decoupled in two polarization directions, electromagnetic waves on one polarization do not affect the varactors on the other polarization, and are reflected on cross polarization, for example, fig. 9 is a cross polarization amplitude diagram of the dual-polarization 3-bit phase independently adjustable reconfigurable intelligent super-surface unit insensitive to the incident angle, and it can be seen that the cross polarization in the diagram is less than-30 dB, so that the unit can independently perform phase control on two polarizations.
In order to research the specific performance of the structure of the dual-polarized 3-bit phase independently adjustable reconfigurable intelligent super-surface unit insensitive to the incident angle, full-wave simulation software CST is utilized to simulate the structure, FIG. 10 is a reflected wave amplitude diagram of 8 coding states of the dual-polarized 3-bit phase independently adjustable reconfigurable intelligent super-surface unit insensitive to the incident angle under the x-axis polarization and the y-axis polarization respectively, and FIG. 11 is a reflected wave phase diagram of 8 coding states of the dual-polarized 3-bit phase independently adjustable reconfigurable intelligent super-surface unit insensitive to the incident angle under the x-axis polarization and the y-axis polarization respectively. As can be seen from fig. 10 and 11, at 2.55GHz, the amplitudes and phases of the reflected waves under the two polarizations are consistent, the amplitude of each state is greater than-3 dB, and the maximum adjustable range of the phase also satisfies 315 ° required for 3-bit phase encoding. In addition, since the capacitance of the varactor is continuously varied, 8 phase-encoded states with a phase interval of about 45 ° can be easily found, and the equivalent capacitance parameters of the varactor are shown in table 2.
TABLE 2
| Status of state | Equivalent capacitance | x-polarization reflection phase | Phase of y- |
| 0 | 1.740pF | -184° | -184° |
| 1 | 0.850pF | -139° | -139° |
| 2 | 0.798pF | -95° | -96° |
| 3 | 0.774pF | -49° | -52° |
| 4 | 0.756pF | -2° | -7° |
| 5 | 0.737pF | 44° | 40° |
| 6 | 0.716pF | 87° | 84° |
| 7 | 0.636pF | 132° | 131° |
Taking the state 4 as an example, fig. 12 is a reflected wave amplitude diagram of the state 4 under oblique incidence of the dual-polarized 3-bit phase independently adjustable reconfigurable intelligent super-surface unit insensitive to the incidence angle, and fig. 13 is a reflected wave phase diagram of the state 4 under oblique incidence of the dual-polarized 3-bit phase independently adjustable reconfigurable intelligent super-surface unit insensitive to the incidence angle. Fig. 12 and 13 show the reflection amplitude and phase of the TE wave and the TM wave respectively when the TE wave and the TM wave are incident at 45 ° oblique angles. Further, in order to verify the insensitivity of the incident angle and the specificity of the varactor capacitance, the amplitude phase of the reflected wave in 8 phase-encoded states of 2.55GHz was more finely simulated at 22.5 ° intervals in the cell at oblique TE and TM incidence, and the results are shown in table 2. It can be seen that at 2.55GHz, the amplitude of the reflected wave under 45-degree oblique incidence of each coding state is larger than-3 dB, the phase deviation value is basically within the maximum quantization error, namely 22.5 degrees compared with the normal incidence, and the error range required by 3-bit phase modulation is met.
TABLE 3
The unit of the invention is utilized to design a 3bit dual-beam RIS which is composed of 30 units by 30 units and can independently carry out beam scanning on two orthogonal polarizations, and the side length is 399mm at 2.55GHz and is about 3.4 lambda0Wherein λ is0The wavelength of the electromagnetic wave in free space is 2.55 GHz. Phase encodings with reflection angles of 0 °, 10 °, 20 °, 30 °, and 40 ° at normal incidence were calculated and simulated. FIG. 14 shows the beam scanning result in the x-axis direction after the dual-polarization 3bit phase-independent adjustable reconfigurable intelligent super-surface unit array insensitive to the incident angle is adopted. FIG. 15 shows the beam scanning result in the y-axis direction after the dual-polarization 3bit phase-independent adjustable reconfigurable intelligent super-surface unit array insensitive to the incident angle is adopted. Fig. 14 and 15 show the operating frequency of 2.55 GHz. Wherein the beam pointing direction is within substantially 1.5 deg. of the theoretical value. In order to verify the angular stability of the RIS at oblique incidence, the incident wave is made to impinge on the RIS at an angle of incidence of 40 °, while its phase code remains the phase code that emerges at an angle of incidence of 0 ° and 40 °. Fig. 16 is a 0-degree outgoing directional diagram of the reconfigurable intelligent super-surface unit array insensitive to the incident angle, which is capable of adjusting the dual-polarization 3bit phase independently and obliquely incident at 40 degrees in the x-axis direction. From fig. 16, it can be seen that the reflected wave is emitted vertically, which demonstrates that the RIS still maintains the same phase gradient at oblique incidence as at normal incidence, i.e., the RIS is insensitive to the angle of incidence.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (8)
1. The reconfigurable intelligent super-surface unit with the dual-polarization 3-bit phase independently adjustable is characterized by comprising four layers of functional structures, wherein a second layer and a third layer are feed layers, and the fourth layer is a metal ground; the upper surface of the unit is a first layer, the lower surface of the unit is a fourth layer, the upper surface and the lower surface of the unit are both square, and the side lengths are equal, namely the side length of the unit; the first layer comprises four isosceles right triangle metal patches and four cross-shaped metal patches, and each isosceles right triangle is connected with a corresponding cross-shaped metal patch through a varactor; the four isosceles right triangle metal patches are respectively connected with one metal through hole, two metal through holes in the x-axis direction are connected with the second layer of feed layer, and two metal through holes in the y-axis direction are connected with the third layer of feed layer; by adjusting the voltages at two ends of the varactor in two orthogonal polarization directions, the unit realizes 3bit phase modulation within an oblique incidence range of 0-45 degrees in the two orthogonal polarization directions independently, so that the unit realizes beam scanning functions in the two polarization directions in a decoupling manner and is insensitive to electromagnetic wave incidence angles.
2. The dual-polarization 3bit phase-independently adjustable reconfigurable intelligent super-surface unit of claim 1, wherein the first layer comprises a square metal patch and a square ring metal patch, the square metal patch is located at the center of the first layer and inside the square ring metal patch, and the diagonals of the square metal patch and the square ring metal patch coincide; the first layer also comprises four rectangular metal patches, and each edge of the square-ring metal patch is vertically crossed with one rectangular metal patch to form a cross-shaped structure; dividing the square metal patch and the square ring metal patch along the diagonal line by using a gap, dividing the square metal patch along the diagonal line to form four isosceles right triangle metal patches, and dividing the square metal patch along the diagonal line to form four cross metal patches; each isosceles right triangle metal patch is connected with the nearest cross metal patch by a varactor.
3. The dual-polarization 3-bit phase-independent adjustable reconfigurable intelligent super-surface unit of claim 2, wherein a square annular metal strip serving as a ground wire is further attached to the periphery of the first layer, and the side length of the square annular metal strip is the unit side length; each side of the square annular metal strip is directly connected with one side of the rectangular metal patch in the cross-shaped metal patch.
4. The dual-polarization 3bit phase-independent adjustable reconfigurable intelligent super-surface unit of claim 3, wherein a rectangular coordinate system is set with the first layer as a reference, and one side of the square metal patch is taken as the x-axis direction, and the other side of the square metal patch, which is perpendicular to the x-axis, is taken as the y-axis direction; the second layer is a first square metal feed layer, the side of the first square metal feed layer is parallel to the corresponding side of the square annular metal strip, and the side length is smaller than that of the square annular metal strip; a first metal strip and a second metal strip are respectively arranged on the edge of the first square metal feed layer in the positive and negative directions of the y axis and are used for connecting the square annular metal strips; the third layer is a second square metal feed layer, the side of the second square metal feed layer is parallel to the corresponding side of the square annular metal strip, and the side length is smaller than that of the square annular metal strip; the side lengths of the second square metal feed layer and the first square metal feed layer are equal; and a third metal strip and a fourth metal strip are respectively arranged on the edge of the second square metal feed layer in the positive and negative directions of the x axis and are used for connecting the square annular metal strips.
5. The dual-polarization 3-bit phase-independent adjustable reconfigurable intelligent super-surface unit of claim 4, wherein the fourth layer is a square metal ground, the sides of the square metal ground are parallel to the corresponding sides of the square annular metal strip, and the side length is equal to the unit side length, i.e., each side of the square metal ground is directly connected with the square annular metal strip.
6. The dual-polarization 3-bit phase-independently adjustable reconfigurable intelligent super-surface unit of claim 5, wherein four isosceles right triangle metal patches are respectively connected with one metal via hole in the x-axis direction and the y-axis direction of the first layer, and the metal via holes are perpendicular to the plane of the first layer and penetrate through the second layer, the third layer and the fourth layer; the two metal through holes in the x-axis direction are connected with the first square metal feed layer of the second layer, and the two metal through holes in the x-axis direction are not connected with the second square metal feed layer of the third layer; the two metal through holes in the y-axis direction are connected with the second square metal feed layer of the third layer, and the two metal through holes in the y-axis direction are not connected with the first square metal feed layer of the second layer; the four metal via holes are not connected with the square metal ground of the fourth layer.
7. The dual-polarized 3-bit phase-independently adjustable reconfigurable intelligent super-surface unit of claim 6, wherein the relative dielectric constant of the first dielectric layer between the first layer and the second layer is εr2.65, polytetrafluoroethylene F4B with a loss tangent tan δ of 0.001; the relative dielectric constant of the second dielectric layer between the second layer and the third layer is epsilonr3.7 Rogers RO4450 prepreg with loss tangent tan δ of 0.004; the relative dielectric constant of the third dielectric layer between the third layer and the fourth layer is epsilonrPolytetrafluoroethylene F4B having a loss tangent tan δ of 0.001 was used as 2.65.
8. The dual-polarized 3bit phase independently adjustable reconfigurable intelligent super surface unit of claim 7, wherein the varactor model is SMV 1405; when a voltage of 11v is applied to the two sides of the varactor, the equivalent RLC model is that a resistor of 0.36 omega, an inductor of 0.7nH and a capacitor of 0.76pF are connected in series.
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| CN114597665A (en) * | 2022-03-22 | 2022-06-07 | 深圳大学 | Transmission super-surface array |
| CN114824817A (en) * | 2022-05-13 | 2022-07-29 | 广东柏兹电子科技有限公司 | Wide-angle dual-polarized 1-Bit programmable super surface |
| CN114976667A (en) * | 2022-07-29 | 2022-08-30 | 安徽大学 | 3bit dual polarization phase adjustable reconfigurable intelligent super surface |
| WO2023179306A1 (en) * | 2022-03-21 | 2023-09-28 | 中兴通讯股份有限公司 | Metasurface unit and base station thereof |
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| WO2023179306A1 (en) * | 2022-03-21 | 2023-09-28 | 中兴通讯股份有限公司 | Metasurface unit and base station thereof |
| CN114597665A (en) * | 2022-03-22 | 2022-06-07 | 深圳大学 | Transmission super-surface array |
| CN114597665B (en) * | 2022-03-22 | 2023-09-29 | 深圳大学 | Transmission super-surface array |
| CN114824817A (en) * | 2022-05-13 | 2022-07-29 | 广东柏兹电子科技有限公司 | Wide-angle dual-polarized 1-Bit programmable super surface |
| WO2023241589A1 (en) * | 2022-06-16 | 2023-12-21 | 中兴通讯股份有限公司 | Reflective intelligent metasurface unit, reflective intelligent metasurface and communication device |
| CN114976667A (en) * | 2022-07-29 | 2022-08-30 | 安徽大学 | 3bit dual polarization phase adjustable reconfigurable intelligent super surface |
| CN114976667B (en) * | 2022-07-29 | 2022-11-15 | 安徽大学 | 3bit dual-polarization phase-adjustable reconfigurable intelligent super surface |
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| CN117458160A (en) * | 2023-12-22 | 2024-01-26 | 江苏赛博空间科学技术有限公司 | Broadband dual-polarized 1bit metamaterial unit structure |
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