A broadband intelligent metasurface

Abstract

The present invention discloses a broadband intelligent metasurface. An open rectangular ring metal slot is added to each of the left and right parts of the metal radiation patch. The two added open rectangular ring metal slots are symmetrically placed inside the metal radiation patch with their openings facing inwards. In this way, when the intelligent metasurface unit is in the off state, the two open rectangular ring metal slots will introduce a new resonant mode with a frequency of f4, thereby expanding the phase shift range of the intelligent metasurface unit and increasing the phase bandwidth of the intelligent metasurface unit. Compared with the traditional intelligent metasurface, the broadband intelligent metasurface of the present invention has a wider operating bandwidth, improves the channel capacity of the communication system, supports a higher data transmission rate, better resists multipath interference and frequency selective fading, thereby improving the reliability of the signal and the communication quality. The broadband intelligent metasurface of the present invention can be used to simultaneously regulate electromagnetic signals in a wide frequency band with a single piece, effectively saving the design and deployment costs of the intelligent metasurface in application deployment.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and more specifically, relates to a broadband intelligent metasurface. Background Art

[0002] With the continuous development of 5G / B5G communication technologies, the demand for high transmission rates by various communication devices is increasing day by day. According to Shannon's theorem, the communication transmission rate is directly related to the signal bandwidth. Therefore, to meet the application requirements of high communication rates, wireless communication systems are gradually expanding to higher frequencies to obtain large-bandwidth spectrum resources. However, high-frequency signals have short wavelengths and small coverage ranges. Traditional technical solutions such as increasing the number of stations and active relays can expand the coverage range of high-frequency signals, but at the same time, they also greatly increase the cost and power consumption of the communication system.

[0003] Reconfigurable Intelligent Surface (RIS) is a new type of electromagnetic metamaterial technology, which has advantages such as low cost, low power consumption, and flexible deployment. By regulating the electromagnetic characteristics such as the phase, amplitude, and polarization of each unit on the intelligent metasurface, the propagation direction of electromagnetic waves in space can be dynamically controlled, thereby opening up new transmission paths in wireless communication systems. Using the intelligent metasurface to assist base station communication can expand its signal coverage range at a lower cost and power consumption, thereby improving the channel environment.

[0004] A millimeter-wave intelligent metasurface unit and a millimeter-wave intelligent metasurface are disclosed in the Chinese invention patent authorized and announced on May 31, 2022, with the authorization announcement number CN113206386B, as Figure 1As shown in the figure, it includes: a first metal layer 1, a first dielectric substrate 2, a second metal layer 3, a second dielectric substrate 4, and a feeding layer stacked in sequence; the first metal layer 1 is a square structure, and a long strip-shaped branch extends from one side of one of its wide sides, on which a slot is etched, and a switching device 6 is loaded at the slot; the second metal layer 3 serves as a metal ground; one end 7 of the long strip-shaped branch away from the square structure is connected to the second metal layer 3 through a conductive column passing through a via hole on the first dielectric substrate 2; the feeding layer serves as the positive electrode; the feeding layer is connected to the center of the first metal layer 1 through a second conductive column passing through via holes on the second dielectric substrate 4, the second metal layer 3, and the first dielectric substrate 2 in sequence; in different states of the switching device 6, the unit presents two different logic states. The invention can solve the problems of millimeter-wave occlusion and too high equipment deployment cost in millimeter-wave communication. For the millimeter-wave intelligent metasurface unit provided by the invention, there is an explicit analytical expression relationship between the length px and width py of the first metal layer 1 and the desired operating frequency and the reflection phase difference at the operating frequency. By adjusting the length px and width py of the first metal layer, millimeter-wave communication at any operating frequency within the millimeter-wave frequency band of 5G communication (including n257 frequency band, n258 frequency band, n261 frequency band, n259 frequency band, and n260 frequency band) can be realized, and its applicable range is wider, and it can better be applied to the millimeter-wave frequency band of 5G communication.

[0005] As Figure 1 shown, the intelligent metasurface of this invention patent can realize the millimeter-wave frequency band of 5G communication by adjusting the length px and width py of the first metal layer 1. However, once the length and width of the square structure of the first metal layer 1 are given, the processed intelligent metasurface works in the millimeter-wave frequency band of communication, and the working bandwidth is narrow, making it difficult to meet the application requirements of large bandwidth and high communication rate, which will limit the application potential of the intelligent metasurface-assisted mobile communication.

[0006] In a Chinese invention patent application published on October 24, 2023, with the publication number CN116937173A, a millimeter-wave band reconfigurable reflection metasurface unit and its beamforming device are disclosed. As Figure 2 shown, by loading a PIN diode phase shifter 6, a short-circuit sector 7, and unit control leads in the millimeter-wave band reconfigurable reflection metasurface unit, and using a shift register to fan out each unit control signal, the intensity, phase, and polarization of electromagnetic waves can be significantly adjusted, so that the reconfigurable metasurface has a very wide working frequency bandwidth. The PIN diode can achieve 0° and 180° phase shifts for vertically polarized electromagnetic waves in the on and off states. The feed horn feeds the center of the reconfigurable metasurface. Through the phase shift coding of the FPGA control board, the reconfigurable metasurface can achieve efficient beamforming, and has the characteristics of compact structure, microwave digital circuit control integration, wide beam scanning range, high beam gain and low sidelobes, low microwave loss, and low cost.

[0007] like Figure 2 As shown, the PIN diode phase shifter 6 includes a first T-shaped patch 6-1 and a second T-shaped patch 6-2 symmetrically arranged to form an I-shaped structure, a gap 6-3 is left between the first T-shaped patch 6-1 and the second T-shaped patch 6-2, and the PIN diode 6-4 is connected to the center between the first T-shaped patch 6-1 and the second T-shaped patch 6-2 across the gap 6-3. This structure enables the millimeter wave frequency band reconfigurable reflective metasurface unit provided by the invention to operate at a millimeter wave frequency of 26-30GHz. The operating frequency band has increased, but it is still difficult to meet the application requirements of large bandwidth and high communication rate. Therefore, research on intelligent metasurfaces with a wide operating frequency band has great application value. Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings of the existing technology, which has a narrow bandwidth and is difficult to meet the needs of broadband high-speed mobile communications, and to provide a broadband intelligent metasurface that can increase the channel capacity of the communication system, support higher data transmission rates, and better resist multipath interference and frequency selective fading, thereby improving signal reliability and communication quality.

[0009] To achieve the above-mentioned purpose, the broadband intelligent metasurface of the present invention is composed of multiple periodically arranged intelligent metasurface units. The DC control channel of each intelligent metasurface unit is independently designed. Each intelligent metasurface unit includes a five-layer structure, which includes the following from top to bottom:

[0010] The first layer is a metal radiation patch, which receives incident electromagnetic waves in space and radiates them into free space after phase modulation.

[0011] The second layer structure is a first dielectric substrate, and the metal radiation patch is placed on the first dielectric substrate;

[0012] The third layer structure is a metal floor, attached to the bottom of the first dielectric substrate;

[0013] The fourth layer structure is the second dielectric substrate, which is placed under the metal floor;

[0014] The fifth layer structure is a metal DC feed network, which is placed below the second dielectric substrate;

[0015] The metal radiation patch is divided into left and right parts by a longitudinal metal slot. The left and right parts are respectively connected to the positive and negative electrodes of the reconfigurable switching device. Among them, the part connected to the positive electrode of the reconfigurable switching device passes through the first dielectric substrate, the metal floor, and the second dielectric substrate through a positive electrode metal via and is connected to the positive electrode corresponding to this intelligent metasurface unit in the metal DC feeding network. A metal isolation ring is arranged at the position of the positive electrode metal via in the metal floor to isolate the positive electrode metal via from the metal floor. The part connected to the negative electrode of the reconfigurable switching device passes through the first dielectric substrate, the metal floor, and the second dielectric substrate through a negative electrode metal via and is connected to the negative electrode corresponding to this intelligent metasurface unit in the metal DC feeding network. The negative electrode metal via is connected to the metal floor in the metal floor;

[0016] It is characterized in that the reconfigurable switching device is placed on the longitudinal metal slot to connect the left and right parts of the metal radiation patch. The width W of the longitudinal metal slot s1 and the length L of the reconfigurable switching device p1 satisfy the relational expression: W s1 < L p1 , and the length L of the longitudinal metal slot s1 satisfies:

[0017]

[0018] where ε r1 is the dielectric constant of the first dielectric substrate, f2 is the frequency of the resonant mode increased by the longitudinal metal slot in the on state of the intelligent metasurface unit, and c is the speed of light in free space;

[0019] The left and right parts of the metal radiation patch are of the same size and each has an open rectangular ring metal slot. The open rectangular ring metal slots are symmetrically placed left and right with the openings facing inwards within the metal radiation patch. The width W in the left - right direction of the open rectangular ring metal slot s2 and the width W in the left - right direction of the metal radiation patch of the left and right parts p1 need to satisfy W p1 > W s2 , and the dimensions of the open rectangular ring metal slot need to satisfy:

[0020]

[0021] W s2 ≤ L s2 ≤ 1.5×W s2

[0022] where L s2 is the length in the up - down direction of the open rectangular ring metal slot, L sub is the length of the opening part of the open rectangular ring metal slot, and f4 is the frequency of the resonant mode increased by the open rectangular ring metal slot in the off state of the intelligent metasurface unit.

[0023] The object of the present invention is achieved as follows.

[0024] On the basis of the existing left and right parts of the metal radiation patch, the broadband intelligent metasurface of the present invention adds an open rectangular ring metal slot to each of the left and right parts. The two added open rectangular ring metal slots are symmetrically placed inside the metal radiation patch with their openings facing inwards. In this way, when the intelligent metasurface unit is in the off state, the two open rectangular ring metal slots will introduce a new resonant mode with a frequency of f4, thereby expanding the phase shift range of the intelligent metasurface unit and increasing the phase bandwidth of the intelligent metasurface unit.

[0025] Compared with the prior art, the broadband intelligent metasurface of the present invention has the following advantages and beneficial effects:

[0026] 1. For the broadband intelligent metasurface of the present invention, the phase shift range of 180±20° is 23.8 - 45.5 GHz, and the relative operating bandwidth is 62.6%. Compared with the traditional intelligent metasurface, the broadband intelligent metasurface of the present invention has a wider operating bandwidth. According to Shannon's theorem, it can improve the channel capacity of the communication system and support higher data transmission rates;

[0027] 2. The broadband intelligent metasurface of the present invention can process electromagnetic signals in multiple frequency bands simultaneously, thereby improving the flexibility and degrees of freedom of the communication system. Thanks to the wide - band characteristics, the broadband intelligent metasurface of the present invention can better resist multipath interference and frequency - selective fading, thereby improving the reliability of the signal and the communication quality;

[0028] 3. When traditional narrow - band intelligent metasurfaces assist broadband wireless communication, multiple narrow - band intelligent metasurfaces need to be designed and deployed to cover wide - band signals. However, only the broadband intelligent metasurface of the present invention can be used to simultaneously regulate electromagnetic signals in a wide frequency band with a single unit, effectively saving the design and deployment costs of intelligent metasurfaces in application deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of a millimeter - wave intelligent metasurface unit in the prior art;

[0030] Figure 2 is a schematic structural diagram of a millimeter - wave - band reconfigurable reflection metasurface unit in the prior art;

[0031] Figure 3 is a schematic structural diagram of a specific embodiment of the broadband intelligent metasurface of the present invention;

[0032] Figure 4 is an exploded view of the structure of a specific embodiment of the intelligent metasurface unit of the broadband intelligent metasurface of the present invention;

[0033] Figure 5 isFigure 4 Reflection phase curve diagrams of the intelligent metasurface unit shown in the on and off states;

[0034] Figure 6 is Figure 4 Reflection phase difference curve diagrams of the intelligent metasurface unit shown in the on and off states;

[0035] Figure 7 is Figure 4 Reflection amplitude curves of the intelligent metasurface unit shown in the on and off states;

[0036] Figure 8 is a schematic diagram of the broadband evolution process of the intelligent metasurface unit in the broadband intelligent metasurface of the present invention. Among them, the upper row is the structural evolution process, and the lower row is the reflection characteristic curve diagrams of the corresponding intelligent metasurface unit in the on and off states;

[0037] Figure 9 is the phase difference curve in the on and off states during the broadband evolution process of the intelligent metasurface unit in the broadband intelligent metasurface of the present invention;

[0038] Figure 10 is a schematic diagram of the structure of a specific implementation manner of a broadband intelligent metasurface array composed of 16×16 intelligent metasurface units;

[0039] Figure 11 is Figure 10 Schematic diagram of the feeding line network of the broadband intelligent metasurface array shown; Specific implementation manner

[0040] The specific implementation manner of the present invention will be described below with reference to the accompanying drawings, so that those skilled in the art can better understand the present invention. It should be particularly noted that in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

[0041] The broadband intelligent metasurface is formed by periodically arranging multiple intelligent metasurface units, and the DC control channels of each intelligent metasurface unit are independently designed. The intelligent metasurface unit is usually composed of a reconfigurable switching device, a radiation metal layer, a dielectric substrate layer, and a metal floor, and the intelligent metasurface unit can be equivalent to a single-mode resonant circuit. By independently controlling the switching signals of each unit on the broadband intelligent metasurface, the resonant frequency and phase state of the unit are changed, so as to realize the dynamic regulation of electromagnetic waves in space.

[0042] Traditional intelligent metasurface units only excited one resonant mode f1 and f3 in the on and off working states respectively. And since the phase curve ranges of single-mode resonant circuits are all (-180°, 180°). Therefore, there is only one extreme point in the phase difference curve of the traditional intelligent metasurface unit in the on and off states. The working bandwidth index of the intelligent metasurface unit is generally the frequency range where the phase difference is in the range of 180±20°. However, the phase difference curve of the traditional intelligent metasurface unit has only one extreme point, which results in its limited working bandwidth.

[0043] The phase curve range of the intelligent metasurface unit is related to the resonant circuit. Based on the single-mode resonance of the intelligent metasurface unit itself, a new resonant structure is introduced to expand the phase curve range of the unit, thus introducing multiple extreme points in the phase difference curve of the unit in the on and off states. By regulating the relative positions of the resonant frequencies of each resonant structure, the extreme points of the phase difference curve of the unit in the on and off states are adjusted to achieve the expansion of the unit bandwidth.

[0044] If the resonant frequencies of the intelligent metasurface units in the on state are f1, f2, … f n (where f1 represents the single-mode resonant frequency of the intelligent metasurface unit in the on state, f2, … f n represent the resonant frequencies of the newly introduced circuits); the resonant frequencies of the units in the off state of the intelligent metasurface are f n+1 , f n+2 , … f n+m (where f n+1 represents the single-mode resonant frequency of the intelligent metasurface unit in the off state, f n+2 , … f n+m represent the resonant frequencies of the newly introduced circuits, and the value range of m is n - 1, n, n + 1). To achieve the expansion of the unit phase, the resonant frequencies need to satisfy the inequality f1 < f n+1 < f2 < f n+2 < … < f n < f n+m or f n+1 < f1 < f n+2 < f2 < … < f n+m < f n . The more resonant circuits are introduced in the intelligent metasurface unit in the on and off states, the greater the expansion of the unit phase bandwidth.

[0045] The number of extreme points N of the phase difference curve between the on and off states of the intelligent metasurface unit is related to the number of resonant modes of the intelligent metasurface unit in the on and off states (the number of resonant modes of the intelligent metasurface unit in the on state is n, and the number of resonant modes of the intelligent metasurface unit in the off state is m). The specific mathematical relationship is N = m + n - 1. Therefore, introducing new resonant modes can increase the number of extreme points of the phase difference curve between the on and off states of the intelligent metasurface unit, and optimize the extreme points within the range of 180 ± 20° by regulating the position of the resonant modes, thereby effectively expanding the phase bandwidth of the intelligent metasurface unit.

[0046] Based on the above design concept, the present invention designs a broadband intelligent metasurface, which can improve the channel capacity of the communication system, support higher data transmission rates, better resist multipath interference and frequency selective fading, thereby improving the reliability of the signal and the communication quality. Specifically as follows:

[0047] In this embodiment, as Figure 1 shown, the broadband intelligent metasurface of the present invention is formed by periodically arranging a plurality of intelligent metasurface units. The DC control channels of each intelligent metasurface unit are independently designed. Each intelligent metasurface unit includes a five-layer structure, which includes, from top to bottom:

[0048] The first layer structure is a metal radiation patch 1, whose function is to receive the incident electromagnetic wave in space, and after phase modulation, radiate it into free space;

[0049] The second layer structure is a first dielectric substrate 2, and the metal radiation patch 1 is placed above the first dielectric substrate 2. The first dielectric substrate 2 is placed below the metal radiation patch 1, and its function is to act as a high-frequency dielectric material to support the metal structures on the upper and lower surfaces, and to affect the propagation speed and characteristic impedance of the electromagnetic wave;

[0050] The third layer structure is a metal floor 3, which is attached to the lower surface of the first dielectric substrate 2 and is used to reflect electromagnetic waves;

[0051] The fourth layer structure is a second dielectric substrate 4, which is placed below the metal floor 3, and its main function is to support the DC feeding network 5 and will not interfere with the electromagnetic wave;

[0052] The fifth layer structure is a metal DC feeding network 5, which is placed below the second dielectric substrate 4 and is used to regulate the unit state.

[0053] Figure 4 is an exploded view of the structure of a specific embodiment of the intelligent metasurface unit of the broadband intelligent metasurface of the present invention.

[0054] In this embodiment, as Figure 4As shown, it can be seen that a longitudinal metal slot 8 and a pair of open rectangular ring metal slots 6 are loaded on the metal radiation patch 1 in the first layer structure of the intelligent metasurface unit. The metal slot can be equivalent to a parallel resonance circuit. The longitudinal metal slot 8 and a pair of open rectangular ring metal slots 6 respectively add a resonance at frequencies f2 and f4 in the off and on states of the intelligent metasurface unit (state 1 is the off state, and state 2 is the on state), thereby increasing the phase bandwidth of the unit. In this way, together with the resonance frequency f1 of the intelligent metasurface unit itself in the on state and the resonance frequency f3 in the off state, the intelligent metasurface unit has two resonance frequencies f1 and f2 in the on state and two resonance frequencies f3 and f4 in the off state.

[0055] In addition to introducing a new resonance mode in the on state of the intelligent metasurface unit, the longitudinal metal slot 8 also extends the current path of the intelligent metasurface unit in the on state, thereby reducing the resonance frequency f1 of the intelligent metasurface unit itself in the on state.

[0056] Specifically, as Figure 4 shown, the metal radiation patch 1 is divided into left and right parts by a longitudinal metal slot 8. The left and right parts are respectively connected to the positive and negative electrodes of the reconfigurable switching device 7. Among them, the part connected to the positive electrode of the reconfigurable switching device 7 passes through the first dielectric substrate 2, the metal floor 3, and the second dielectric substrate 4 through the positive electrode metal via (the left metal via 9) and is connected to the corresponding positive electrode in the metal DC feeding network 5 of this intelligent metasurface unit. A metal isolation ring 10 is provided at the positive electrode metal via (the left metal via 9) in the metal floor 3 to isolate the positive electrode metal via (the left metal via 9) from the metal floor 3. The part connected to the negative electrode of the reconfigurable switching device 7 passes through the first dielectric substrate 2, the metal floor 3, and the second dielectric substrate 4 through the negative electrode metal via (the right metal via 9) and is connected to the corresponding negative electrode in the metal DC feeding network 5 of this intelligent metasurface unit. The negative electrode metal via (the right metal via 9) in the metal floor 3 is connected to the metal floor 3.

[0057] In order to isolate the radio frequency signal and the DC control signal, a metal filtering fan-shaped branch 11 is loaded at the connection between the corresponding positive electrode of the intelligent metasurface unit in the metal DC feeding network 5 and the positive electrode metal via (the left metal via 9). The metal filtering fan-shaped branch 11 is equivalent to a capacitor, which can filter out the high-frequency signal on the metal DC feeding network 5, thereby eliminating the influence of the metal DC feeding network 5 on the reflection performance of the intelligent metasurface unit.

[0058] In this embodiment, the first dielectric substrate 2 is made of high-frequency dielectric plates such as F4BTMS-220 and Rogers 5880, with a dielectric constant of 2.2 and a thickness of 1.016 mm. The second dielectric substrate 4 is made of FR4 plates, with a dielectric constant of 4.4 and a thickness of 0.2 mm.

[0059] In this embodiment, the model of the reconfigurable switch device 7 is madp000907-14020P.

[0060] In this embodiment, the copper foil thickness of the metal radiation patch 1 and the metal DC feed network 5 is 1 oz, and the copper foil thickness of the metal floor 3 is 0.5 oz.

[0061] In this embodiment, the reconfigurable switch device 7 is placed on the longitudinal metal slot 8, connecting the left and right parts of the metal radiation patch 1. The width W s1 of the longitudinal metal slot 8 and the length L p1 of the reconfigurable switch device 7 s1 satisfy the relation: W p1 < L s1 , and the length L

[0062]

[0063] where ε r1 is the dielectric constant of the first dielectric substrate 2, f2 is the frequency of the resonant mode increased by the longitudinal metal slot 8 in the on state of the intelligent metasurface unit, and c is the speed of light in free space.

[0064] In this embodiment, the length L s1 of the longitudinal metal slot 8 is 2.92 mm, and the width W s1 is 0.2 mm.

[0065] In this embodiment, as Figure 4 shown, the left and right parts of the metal radiation patch 1 are of the same size, and each has an open rectangular ring metal slot 6. The open rectangular ring metal slots 6 are symmetrically placed with their openings facing inwards in the metal radiation patch 1. The width W s2 in the left-right direction of the open rectangular ring metal slot 6 and the width W p1 in the left-right direction of the left and right parts of the metal radiation patch 1 p1 need to satisfy W s2 > W

[0066]

[0067] W s2 ≤ L s2 ≤ 1.5×W s2

[0068] where L s2 is the length in the up-down direction of the open rectangular ring metal slot 6, and L subis the length of the opening part of the open rectangular ring metal slot 6, and f4 is the frequency of the resonant mode increased by the open rectangular ring metal slot 6 in the off state of the intelligent metasurface unit.

[0069] In this embodiment, considering the limitations of the actual processing technology, the minimum copper wire width of the processing technology is W c , then it is necessary to satisfy W p1 >W s2 +2×W c .

[0070] In this embodiment, the length L s2 in the up and down direction of the open rectangular ring metal slot 6 is 1.1 mm, and the width W s2 in the left and right direction is 0.8 mm, the length L sub of the opening part is 0.48 mm, and the slot width W sr2 is 0.1 mm.

[0071] In this embodiment, the reflection phase curves of the intelligent metasurface unit of the broadband intelligent metasurface of the present invention in the on and off states are as Figure 5 shown. From Figure 5 we can see that the phase curves of the intelligent metasurface unit in the on and off states have high linearity and good parallelism, showing broadband phase shift characteristics.

[0072] In this embodiment, the reflection phase difference curve of the intelligent metasurface unit of the broadband intelligent metasurface of the present invention in the on and off states is as Figure 6 shown. From Figure 6 we can see that the reflection phase difference of the intelligent metasurface unit in the on and off states is 180±20°, the phase shift range is 23.8 - 45.5 GHz, and the relative working bandwidth is 62.6%, verifying that the intelligent metasurface unit of the broadband intelligent metasurface of the present invention has broadband characteristics.

[0073] In this embodiment, the reflection amplitude curve of the intelligent metasurface unit of the broadband intelligent metasurface of the present invention in the on and off states is as Figure 7 shown. From Figure 7 we can see that the reflection loss of the unit in the main working frequency band of the intelligent metasurface unit is less than 3 dB.

[0074] Figure 8 is a schematic diagram of the broadband evolution process of the intelligent metasurface unit in the broadband intelligent metasurface of the present invention. Among them, the upper row is the structural evolution process, and the lower row is the reflection characteristic curve diagram of the corresponding intelligent metasurface unit in the on and off states respectively.

[0075] In this embodiment, from Figure 8We can see that the intelligent metasurface unit 1 (referred to as unit 1 for short, and subsequently referred to as unit 2 and unit 3) is a unit with traditional single-mode resonance. The unit has only one resonance mode in both switch states, and the phase shift range of the unit is limited.

[0076] Unit 2 adds a longitudinal metal slot 8 on the basis of unit 1. When the reconfigurable switching device 7 is in the on state, the resonance mode of the longitudinal metal slot 8 between adjacent units is excited, so that the phase shift range of unit 2 in the on state is expanded.

[0077] Adding a pair of open rectangular ring metal slots 6 on the basis of unit 2 results in the final unit 3, which is the intelligent metasurface unit of the present invention. In the off state, the resonance mode of the open rectangular ring metal slot 6 is excited, so that the phase shift range of the intelligent metasurface unit in the off state is expanded. The broadband evolution process of the intelligent metasurface unit verifies that introducing a new resonance mode can expand the phase range of the unit.

[0078] Figure 9 It is the phase difference curve of the intelligent metasurface unit in the broadband intelligent metasurface of the present invention in the on and off states during the broadband evolution process.

[0079] In this embodiment, from Figure 9 We can see that as the resonance modes of the intelligent metasurface unit in the on and off states increase, the number of extreme points of the phase difference curve also increases. The number of resonance modes of the intelligent metasurface unit in the on state is n = 2, the number of resonance modes of the intelligent metasurface unit in the off state is m = 2, and the number of extreme points of the phase difference curve of the intelligent metasurface unit is N = 3. In this way, the mathematical relationship N = n + m - 1 between the number of extreme points N of the phase difference curve of the intelligent metasurface unit and the number of resonance modes of the intelligent metasurface unit in the on and off states is verified (the number of resonance modes of the intelligent metasurface unit in the on state is n, and the number of resonance modes of the intelligent metasurface unit in the off state is m). At the same time, the phase bandwidth of the intelligent metasurface unit expands with the increase in the number of extreme points of the phase difference curve.

[0080] In this embodiment, a broadband intelligent metasurface array composed of 16×16 intelligent metasurface units, that is, an array arranged by 256 units, is as Figure 10 shown.

[0081] In this embodiment, the feeding line network of a broadband intelligent metasurface array composed of 16×16 intelligent metasurface units, that is, an array arranged by 256 units, is as Figure 11 shown.

[0082] Although the above-described illustrative specific embodiments of the present invention have been described to facilitate understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

Claims

1. A broadband intelligent metasurface is formed by periodically arranging multiple intelligent metasurface units. The DC control channels of each intelligent metasurface unit are independently designed. Each intelligent metasurface unit includes a five-layer structure, which successively includes from top to bottom: The first layer structure is a metal radiation patch, whose function is to receive incident electromagnetic waves in space and radiate them into free space after phase modulation; The second layer structure is a first dielectric substrate, and the metal radiation patch is placed above the first dielectric substrate; The third layer structure is a metal ground plane, which is attached to the lower side of the first dielectric substrate; The fourth layer structure is a second dielectric substrate, which is placed below the metal ground plane; The fifth layer structure is a metal DC feeding network, which is placed below the second dielectric substrate; The metal radiation patch is divided into left and right parts by a longitudinal metal slot. The left and right parts are respectively connected to the positive and negative electrodes of the reconfigurable switching device. Among them, the part connected to the positive electrode of the reconfigurable switching device passes through the first dielectric substrate, the metal ground plane, and the second dielectric substrate through a positive electrode metal via and is connected to the corresponding positive electrode in the metal DC feeding network of this intelligent metasurface unit. A metal isolation ring is arranged at the positive electrode metal via in the metal ground plane to isolate the positive electrode metal via from the metal ground plane. The part connected to the negative electrode of the reconfigurable switching device passes through the first dielectric substrate, the metal ground plane, and the second dielectric substrate through a negative electrode metal via and is connected to the corresponding negative electrode in the metal DC feeding network of this intelligent metasurface unit. The negative electrode metal via is connected to the metal ground plane in the metal ground plane; Characterized in that, the reconfigurable switching device is placed on the longitudinal metal slot, connecting the left and right parts of the metal radiation patch, and the width W of the longitudinal metal slot s1 and the length L of the reconfigurable switching device p1 satisfy the relationship: W s1 < L p1 , and the length L of the longitudinal metal slot s1 satisfies: where ε r1 is the dielectric constant of the first dielectric substrate, f2 is the frequency of the resonant mode increased by the longitudinal metal slot in the on-state of the intelligent metasurface unit, and c is the speed of light in free space; The left and right parts of the metal radiation patch are of the same size, and each has an open rectangular ring metal slot. The open rectangular ring metal slots are symmetrically placed inside the metal radiation patch with their openings facing inwards in the left and right directions. The width W of the open rectangular ring metal slot in the left and right directions s2 is the same as the width W of the metal radiation patch in the left and right directions of the left and right parts p1 and needs to satisfy W p1 >W s2 . The dimensions of the open rectangular ring metal slot need to satisfy: W s2 ≤L s2 ≤1.5×W s2 Among them, L s2 is the length of the open rectangular ring metal slot in the up and down direction, and L sub is the length of the opening part of the open rectangular ring metal slot. f4 is the frequency of the resonant mode increased by the open rectangular ring metal slot in the off state of the intelligent metasurface unit.

2. The broadband intelligent metasurface according to claim 1, wherein The minimum copper wire width of the processing technology is W c , then the width W needs to satisfy p1 >W s2 +2×W c .

3. The broadband intelligent metasurface according to claim 1, wherein The length L of the longitudinal metal groove s1 is 2.92 mm, and the width W s1 is 0.2 mm.

4. The broadband intelligent metasurface according to claim 1, wherein The length L of the open rectangular ring metal slot in the up and down direction s2 is 1.1 mm, and the width W in the left and right direction s2 is 0.8 mm. The length L of the opening part sub is 0.48 mm, and the slot width W sr2 is 0.1 mm.

5. The broadband intelligent metasurface according to claim 1, wherein The first dielectric substrate uses a high-frequency dielectric board with a dielectric constant of 2.2 and a thickness of 1.016 mm; the second dielectric substrate uses an FR4 board with a dielectric constant of 4.4 and a thickness of 0.2 mm.

6. The broadband intelligent metasurface according to claim 1, wherein The copper foil thickness of the metal radiation patch and the metal DC feeding network is 1 oz, and the copper foil thickness of the metal ground plane is 0.5 oz.

Images