A full-space programmable metasurface unit with same frequency and same polarization

Abstract

The application is a full-space programmable metasurface unit with the same frequency and polarization, which comprises two layers of dielectric substrates and metal structures arranged in sequence, and the two dielectric substrates are separated by air, wherein the metal structure comprises two metal gratings with an included angle of 90° and two metal resonance structures. top Five diodes are integrated in the metal resonance junction, respectively named D top , D1, D2, D3 and D4, and the conduction and cutoff of the diodes can be controlled by an external DC voltage, thereby realizing independent control of the transmission and reflection phases of electromagnetic waves. Among them, the state of D top controls the reflection phase; the states of D1, D2, D3 and D4 control the transmission phase. The application realizes independent regulation of the transmission and reflection phases of electromagnetic waves at a frequency of 4.75 GHz, ensures that the reflected electromagnetic waves and the transmitted electromagnetic waves have the same polarization characteristics, and ensures that the transmittance and reflectance are greater than -3dB, and is applied in the fields of full-space beam regulation and wireless communication.

Description

Technical Field

[0001] This invention relates to a fully programmable metasurface unit technology with the same frequency and polarization, belonging to the interdisciplinary field of novel artificial electromagnetic materials and antenna technology. More specifically, it is a metasurface unit operating at 4.75 GHz with full-space electromagnetic field control capability, ensuring that transmitted and reflected electromagnetic waves have the same polarization state. Depending on the applied bias voltage, the unit can achieve two phase responses with a phase difference of 180° for the transmitted and reflected electromagnetic waves, thereby realizing independent 1-bit phase control of the transmitted and reflected electromagnetic fields. It also exhibits high transmittance and reflectance, and can be applied in antenna and wireless communication fields. Background Technology

[0002] Programmable metasurface technology is a key emerging technology in the fields of antennas and wireless communication. By controlling the amplitude and phase of electromagnetic fields through metasurfaces, functions such as electromagnetic wave beam scanning and focusing can be achieved, enabling signal blinding, multi-stream transmission, and physical layer security in communications. Compared with traditional transmissive and reflective metasurfaces, full-space metasurfaces can simultaneously control both transmitted and reflected electromagnetic fields, thus showing broad application prospects in indoor wireless communication scenarios. In recent years, many programmable metasurfaces with full-space beam control capabilities have been proposed based on traditional transmissive and reflective metasurfaces. However, to reduce interference between transmitted and reflected waves, most designed full-space metasurfaces cannot guarantee independent control of electromagnetic fields at the same frequency simultaneously, or cannot ensure that the transmitted and reflected electromagnetic fields have the same polarization state. The difference in polarization and frequency between transmitted and reflected waves complicates receiving equipment; therefore, there is an urgent need to develop full-space metasurface units with the same frequency and polarization to achieve independent phase control of transmitted and reflected electromagnetic waves at the same frequency, while ensuring that the transmitted and reflected waves have the same polarization state. Summary of the Invention

[0003] Technical Problem: The purpose of this invention is to provide a fully programmable metasurface unit with the same frequency and polarization, by changing the diode D loaded on the unit. top The bias voltages of diodes D1, D2, D3, and D4 independently regulate the transmission and reflection phases of the metasurface, thereby achieving the purpose of controlling the far-field pattern.

[0004] Technical solution: A fully space-programmable metasurface unit with the same frequency and polarization, comprising:

[0005] A first dielectric substrate layer and a second dielectric substrate layer, with an air layer between them;

[0006] The first metal structure layer includes an "I"-shaped metal patch and a metal strip, wherein the "I"-shaped patch and the metal strip are connected by a diode D. top Connections used for phase modulation of reflected electromagnetic waves;

[0007] The second metal structure layer includes a slotted "X"-shaped metal patch and a ring structure. The four slots are connected to diodes D1, D2, D3 and D4 respectively, which are used for phase modulation of transmitted electromagnetic waves.

[0008] The first metal grating and the second metal grating are respectively disposed on both sides of the dielectric substrate layer with an included angle of 90°, and are used for polarization filtering;

[0009] The diode D top The conduction and cutoff control the reflection phase difference by 180°, and the combined state of diodes D1, D2, D3 and D4 controls the transmission phase difference by 180°. The transmitted wave and the reflected wave have the same frequency and polarization characteristics in the 4.75GHz band.

[0010] Preferably, the diode D top The bias voltages of diodes D1, D2, D3, and D4 are independently adjustable to achieve independent control of the reflection phase; the bias voltages of diodes D1, D2, D3, and D4 are controlled in groups (D1 and D2 are on while D3 and D4 are off, or D3 and D4 are on while D1 and D2 are off) to achieve independent control of the transmission phase.

[0011] Preferably, the width and spacing of the metal strips of the first and second metal gratings are equal, and the electrical dimension is 0.001-0.005 wavelengths, which are used for polarization conversion and filtering.

[0012] Preferably, the electrical thickness of the first dielectric substrate layer and the second dielectric substrate layer is 0.04-0.1 wavelength, and the electrical thickness of the air separator layer is 0.01-0.1 wavelength.

[0013] Preferably, the amplitudes of the transmitted electromagnetic wave and the reflected electromagnetic wave are both greater than -3dB, the phase difference is 180°±5°, and the operating frequency is 4.75GHz.

[0014] Preferably, the electrical dimension of the total width P of the unit is 0.1-1 wavelength, and the electrical dimension thickness of the metal layer is 0.0001-0.01 wavelength.

[0015] Preferably, the electrical length of the "I"-shaped metal patch is approximately 0.3 wavelengths; the diagonal electrical length of the "X"-shaped metal patch is 0.5 wavelengths.

[0016] The present invention also provides a programmable metasurface array, characterized in that it is composed of the aforementioned full-space programmable metasurface units arranged periodically, for realizing full-space beamforming and dynamic control.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following advantages.

[0018] 1. Compared with traditional transmissive or reflective programmable metasurface units, this invention achieves phase modulation of reflection of horizontally polarized incident waves and phase modulation of transmission of vertically polarized incident waves through the "I"-shaped patch on the top layer and the "X"-shaped patch between the two gratings. It can simultaneously and independently control the transmission and reflection of electromagnetic waves, and has a wider range of application prospects.

[0019] 2. Compared with existing fully programmable metasurface units, this invention achieves high transmittance and stable transmission phase difference while ensuring reflectivity and reflection phase difference. This is achieved through a polarization conversion mechanism with an "X"-shaped metal patch loaded with diodes and metal gratings on both sides for polarization filtering.

[0020] 3. Compared to existing fully programmable metasurface units, the "X"-shaped metal patch in the transmission control section has a greater polarization reversal function. Therefore, its vertically polarized incident wave can be converted into a horizontally polarized transmitted wave. By optimizing the dimensions of the "X"-shaped and "I"-shaped metal patches, the metasurface can achieve control of transmitted and reflected waves at the same frequency. The transmitted and reflected electromagnetic waves of this invention have the same frequency and polarization state, which can effectively simplify the complexity of the receiving equipment.

[0021] 4. Compared with existing full-space programmable metasurface units, the present invention contains only four metal layers and two dielectric layers, which makes the processing simple and the processing cost lower. Attached Figure Description

[0022] Figure 1 This is a front view of the metal structure in the unit structure of the present invention.

[0023] Figure 2 This is a side view of the unit structure of the present invention.

[0024] Figure 3 This is a schematic diagram of the power supply of the unit structure of the present invention.

[0025] Figure 4 This is a schematic diagram of the induced electric field when the unit of the present invention modulates electromagnetic waves.

[0026] Figure 5 This is a graph showing the relationship between the reflection amplitude and phase of the unit of the present invention under different diode bias states.

[0027] Figure 6 This is a graph showing the relationship between the transmission amplitude and phase of the unit of the present invention under different diode bias states.

[0028] Figure 7 This is a diagram illustrating the effect of the unit of this invention performing full-space beamforming.

[0029] The figure shows: dielectric substrate 1, dielectric substrate 2, reflection control metal structure layer 3, metal grating 4, transmission control metal structure 5, and metal grating 6. Detailed Implementation

[0030] Example 1

[0031] The same frequency and same polarization full-space programmable metasurface unit of the present invention includes two metal-dielectric-metal structures separated by air, wherein the first metal-dielectric-metal structure includes a reflection control metal structure layer 2, a dielectric substrate 1 and a metal grating 4, and the second metal-dielectric-metal structure includes a projection control metal structure layer 5, a dielectric substrate 2 and a metal grating 6.

[0032] in,

[0033] The metal layer has good electrical conductivity and an electrical dimension thickness ranging from 0.0001 wavelengths to 0.01 wavelengths.

[0034] The dimensions of the "I"-shaped patch in the metal layer 3 are y1 = 8mm, y2 = 3mm, x1 = 14mm, and x2 = 9mm. There is a via connected to the metal layer 4 at the center of the "I"-shaped patch.

[0035] The angle between the metal gratings in the metal layers 4 and 6 is 90°, and the width of the metal portion of the grating is equal to the length of the interval between the metal portions of the grating, with an electrical length of 0.001 to 0.005 wavelengths.

[0036] Metal layer 5 contains a slotted "X"-shaped patch and a ring, and there are vias connected to metal layer 6 at the center and around the patch. The structural dimensions of metal layer 5 are r1 = 5mm, r2 = 12.5mm, r3 = 14.5mm, l1 = 33.8mm, and l2 = 21mm.

[0037] The metal layer is processed on a dielectric substrate having any dielectric constant, and the electrical dimension thickness t of the dielectric substrate is... s From 0.04 wavelength to 0.1 wavelength.

[0038] The air separator air The electrical dimensions range from 0.1 wavelength to 0.1 wavelength.

[0039] The width P of the metal structure layer ranges from 0.1 wavelength to 1 wavelength.

[0040] The electrical length of the "I"-shaped metal patch is approximately 0.3 wavelengths; the diagonal electrical length of the "X"-shaped metal patch is 0.5 wavelengths.

[0041] This invention discloses a fully programmable metasurface unit with the same frequency and polarization, which can simultaneously achieve independent phase control of transmitted and reflected electromagnetic waves, and ensure that the transmitted and reflected waves are in the same polarization state while maintaining high transmittance. When a battery wave with x-polarization and y-polarization is incident, the x-polarized incident wave is completely reflected, while the y-polarized incident wave is converted into an x-polarized transmitted wave. This metasurface unit achieves control over the transmitted and reflected electromagnetic waves by adjusting the conduction and cutoff of diodes integrated on the metasurface unit. Wherein D... top When the diodes are on and off, the reflection phase of the metasurface has a 180° phase difference; the transmission phase has a 180° phase difference in the two states of D1 and D2 being on and D3 and D4 being off, and D3 and D4 being on and D1 and D2 being off. Therefore, 1-bit phase modulation of transmission and reflection can be achieved by controlling the diode states.

[0042] Figure 1 and Figure 2 The invention provides a front and side view of its unit structure, including two metal-dielectric-metal structures separated by air. Metal layer 3 consists of an "I"-shaped patch and metal strips. The dimensions of the "I"-shaped patch are y1 = 8 mm, y2 = 3 mm, x1 = 14 mm, and x2 = 9 mm. The angle between the metal gratings in metal layers 4 and 6 is 90°, and the width of the grating metal portion is equal to the spacing length of the grating metal portion. Its electrical length is 0.001 to 0.005 wavelengths. Metal layer 5 includes a slotted "X"-shaped patch and a ring. Vias connecting to metal layer 6 are present at the center and around the patch. The structural dimensions of metal layer 5 are r1 = 5 mm, r2 = 12.5 mm, r3 = 14.5 mm, l1 = 33.8 mm, and l2 = 21 mm. The metal layer material exhibits excellent conductivity, with an electrical thickness ranging from 0.0001 wavelength to 0.01 wavelength; the metal layer is processed on a dielectric substrate with any dielectric constant, and the electrical thickness t... s From 0.04 wavelength to 0.1 wavelength; air separation t air The electrical thickness ranges from 0.01 wavelength to 0.1 wavelength; the broadband P of the metallic structure layer ranges from 0.1 wavelength to 1 wavelength.

[0043] Figure 3 The power supply structure design of the metasurface unit is presented. By combining the metal structure of the metasurface, the control voltage V1 of the metasurface reflection part and the control voltage V2 of the metasurface transmission part can be independently adjusted, thereby controlling the transmission and reflection phases of the metasurface in a counter-cyclic manner.

[0044] Figure 4A schematic diagram of the induced electric field of the unit in this invention is given. It can be seen that when the operating frequency is 4.75GHz, there is a centrally symmetrical induced electric field in both the states where D1 and D2 are on and D3 and D4 are off, and D3 and D4 are on and D1 and D2 are off. Therefore, the transmitted battery wave has a 180° phase difference. top In both the on and off states, the induced electric field of the metasurface exhibits different resonance states. When D... top At the cutoff point, the metasurface resonance is strong, while D top When the circuit is turned on, the resonance of the metasurface unit is disrupted, resulting in a 180° phase difference in the transmitted cell wave.

[0045] Figure 5 and Figure 6 The amplitude and phase of transmission and reflection of the metasurface under different diode states are given. It can be seen that the metasurface can independently control the transmission and reflection phase of electromagnetic waves near 4.75 GHz, and the amplitude of both reflection and transmission is greater than -3 dB, which shows good phase control capability in the whole space.

[0046] Figure 7 The effect of beamforming achieved by this metasurface is presented. In practical applications, the unit with 0° phase response can be encoded as "0" and the unit with 180° phase response can be encoded as "1". The encoding of the metasurface array can be designed for different transmission angles or reflection angles to achieve beamforming. Figure 7 This indicates that the array composed of this metasurface unit has a good beamforming effect at both the transmission and reflection ends.

[0047] Example 2

[0048] This embodiment provides a programmable metasurface array, which is composed of periodically arranged full-space programmable metasurface units, and is used to realize full-space beamforming and dynamic control.

[0049] 1. Array structure design

[0050] The array adopts a two-dimensional square periodic arrangement with an array size of M×N (M and N are natural numbers) and a unit spacing P of 0.1-1 wavelength (approximately 6.3mm to 63mm in the 4.75GHz band) to ensure no electromagnetic coupling interference between adjacent units.

[0051] Each unit is independently connected to a control board, which integrates a bias voltage distribution network that supplies bias voltage to the diodes D of each unit via wires or flexible circuitry. top D1, D2, D3 and D4 are subjected to DC bias voltages that are controlled independently or in groups.

[0052] 2. Control System Integration

[0053] The central controller generates control signals through an FPGA or microprocessor, converting a preset phase encoding matrix (such as binary "0" and "1", each corresponding to a 180° phase difference) into voltage signals.

[0054] Reflection phase modulation section (D) top Independently controlled from the transmission phase modulation section (D1~D4):

[0055] D top The bias voltage can be adjusted individually to achieve a reflection phase of 0° or 180° for each unit;

[0056] D1 and D2 form one group, and D3 and D4 form another group. The transmission phase can be 0° or 180° by controlling the groups (e.g., the first group is on, the second group is off, or vice versa).

[0057] 3. Beamforming Implementation

[0058] Transmission beam control: The transmission phase distribution is designed using the phase gradient method based on the target transmission direction (azimuth and elevation angle).

[0059] Reflection beam control: Similarly, the reflection phase distribution is designed independently according to the target reflection direction and does not interfere with the transmission beam.

[0060] Dynamic control: By updating the control signal in real time and switching the phase state of the unit, beam scanning, multi-beam generation or adaptive adjustment of beam shape can be achieved.

Claims

1. A fully programmable metasurface unit with the same frequency and polarization, characterized in that, include: A first dielectric substrate layer (1) and a second dielectric substrate layer (2) are separated by an air layer; The first metal structure layer (3) includes an "I"-shaped metal patch and a metal strip. The "I"-shaped metal patch includes two first sides and one second side. The first side of the "I"-shaped patch and the metal strip are connected by a diode D. top Connections used for phase modulation of reflected electromagnetic waves; The second metal structure layer (5) includes a slotted "X"-shaped metal patch and a ring structure. The ring structure is connected to the "X"-shaped metal patch. There is a circular metal patch at the intersection of the "X"-shaped metal patch. The four slots are respectively set on the four arms of the "X"-shaped metal patch and connected to diodes D1, D2, D3 and D4 for phase modulation of transmitted electromagnetic waves. The first metal grating (4) and the second metal grating (6) are respectively disposed on both sides of the dielectric substrate layer with an included angle of 90°, and are used for polarization filtering; the first metal structure layer (3) and the first metal grating (4) are disposed on the upper and lower sides of the first dielectric substrate layer (1); the second metal structure layer (5) and the second metal grating (6) are disposed on the upper and lower sides of the second dielectric substrate layer (2). The diode D top The conduction and cutoff control the reflection phase difference by 180°, and the combined state of diodes D1, D2, D3 and D4 controls the transmission phase difference by 180°. The transmitted wave and the reflected wave have the same frequency and polarization characteristics in the 4.75GHz band.

2. The fully programmable metasurface unit according to claim 1, characterized in that, The diode D top The bias voltages of diodes D1, D2, D3, and D4 can be independently adjusted to achieve independent control of the reflection phase; the bias voltages of diodes D1, D2, D3, and D4 can be independently controlled through group control to achieve independent control of the transmission phase.

3. The fully programmable metasurface unit according to claim 1, characterized in that, The width and spacing of the metal strips of the first metal grating (4) and the second metal grating (6) are equal, and the electrical size is 0.001-0.005 wavelengths, which are used for polarization conversion and filtering.

4. The fully programmable metasurface unit according to claim 1, characterized in that, The electrical thickness of the first dielectric substrate layer (1) and the second dielectric substrate layer (2) is 0.04-0.1 wavelength, and the electrical thickness of the air separator layer is 0.01-0.1 wavelength.

5. The fully programmable metasurface unit according to claim 1, characterized in that, The amplitudes of the transmitted and reflected electromagnetic waves are both greater than -3dB, the phase difference is 180°±5°, and the operating frequency is 4.75GHz.

6. The fully programmable metasurface unit according to claim 1, characterized in that, The electrical dimension of the total width P of the cell is 0.1-1 wavelength, and the electrical dimension of the metal layer is 0.0001-0.01 wavelength.

7. The fully programmable metasurface unit according to claim 1, characterized in that, The electrical length of the "I"-shaped metal patch is 0.3 wavelengths; the diagonal electrical length of the "X"-shaped metal patch is 0.5 wavelengths.

8. A programmable metasurface array, characterized in that, It is composed of periodically arranged full-space programmable metasurface units as described in any one of claims 1-7, and is used to realize full-space beamforming and dynamic control.

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