Omni-directional metasurface unit based on magnetic electric dipole and omni-directional metasurface

Abstract

The application provides an omnidirectional metasurface unit and omnidirectional metasurface based on a magnetic electric dipole, belongs to the field of microwave antennas, and comprises a top patch layer, a first dielectric layer, a bias line layer, a PP layer, a ground layer, a second dielectric layer and a bottom patch layer arranged in sequence from top to bottom, wherein the top patch layer integrates diode D1 and diode D2, the top patch layer comprises a first middle patch layer, a first left patch layer and a first right patch layer, the anode of diode D1 is connected to the first left patch layer, the cathode of diode D1 is connected to the first middle patch layer, the anode of diode D2 is connected to the first right patch layer, the cathode of diode D2 is connected to the first middle patch layer, the first middle patch layer is connected to the bottom patch layer through a via, the first left patch layer and the first right patch layer are respectively connected to the bias line layer through vias, and the bottom patch layer is connected to the ground layer through a via; the omnidirectional metasurface based on the magnetic electric dipole structure has a wideband characteristic, can realize the regulation and control of incident electromagnetic waves in two directions of the top layer and the bottom layer, and realizes the regulation and control of omnidirectional incident electromagnetic waves.

Description

Technical Field

[0001] This invention relates to the field of microwave antenna technology, and in particular to a method for studying broadband omnidirectional metasurfaces constructed using magnetoelectric dipoles. Background Technology

[0002] Currently, metasurfaces are mainly classified into transmission and reflection types. These traditional metasurfaces can only control electromagnetic waves incident within a half-space, which limits their practical applications. In recent years, a more powerful reconfigurable omnidirectional metasurface unit cell capable of both transmission and reflection of incident electromagnetic waves has been proposed. However, these proposed units primarily employ resonant structures, resulting in a narrow operating bandwidth, and their unit cell design cannot achieve control over omnidirectional electromagnetic waves. Due to the reciprocity theorem, the proposed omnidirectional metasurfaces can transmit electromagnetic waves incident throughout space, but reflection is limited to half-space; the metasurface can only reflect electromagnetic waves incident from specific directions.

[0003] like Figure 1 As shown, there are three existing omnidirectional metasurfaces. For transmission, due to the reciprocity theorem, all three designs can control electromagnetic waves incident in all space. However, for reflection, none of the three omnidirectional metasurfaces can control electromagnetic waves incident in all directions. Figure 1 (a) It is a dual-layer design, consisting of a phase control layer (PCL) and a reflection-transmission control layer (RTCL). When an electromagnetic wave is incident from the PCL layer, the electromagnetic wave can be reflected and the phase of the reflected electromagnetic wave can be modulated. When it is incident from the RTCL layer, its phase cannot be modulated. Figure 1 (b) is an omnidirectional metasurface unit with a shared aperture that can reflect x-polarized waves incident from the upper layer and whose phase can be modulated, but the phase of electromagnetic waves incident from the lower layer cannot be modulated. Figure 1 (c) An omnidirectional metasurface unit for an improved receive-retransmit structure, which is designed to integrate a diode in the receiving layer to modulate the phase of the reflected wave, but can only modulate the electromagnetic wave incident from the receiving layer.

[0004] Furthermore, current omnidirectional metasurfaces integrate three or more diodes and do not utilize all the states of the diodes. This leads to state redundancy in the unit and increases manufacturing costs. Moreover, the excessive number of diodes makes the power supply structure more complex, increasing design difficulty. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to solve the problem that existing omnidirectional metasurface units cannot achieve broadband and cannot control omnidirectional incident electromagnetic waves.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: an omnidirectional metasurface unit based on a magnetoelectric dipole, comprising, from top to bottom, a top patch layer, a first dielectric layer, a bias line layer, a PP layer, a ground layer, a second dielectric layer, and a bottom patch layer. The top patch layer integrates diodes D1 and D2. The top patch layer includes a first intermediate patch layer, a first left patch layer, and a first right patch layer. The anode of diode D1 is connected to the first left patch layer, and the cathode of diode D1 is connected to the first intermediate patch layer. The anode of diode D2 is connected to the first right patch layer, and the cathode of diode D2 is connected to the first intermediate patch layer. The first intermediate patch layer is connected to the bottom patch layer through vias. The first left patch layer and the first right patch layer are respectively connected to the bias line layer through vias. The bottom patch layer is connected to the ground layer through vias.

[0007] In the structure of the omnidirectional metasurface of this invention, the top patch layer, the bias line layer, and the vias together constitute a magnetoelectric dipole structure, and the bottom patch layer, the ground layer, and the vias also constitute a magnetoelectric dipole structure. The design based on the magnetoelectric dipole structure enables the omnidirectional metasurface to have broadband characteristics.

[0008] When an electromagnetic wave is incident from the top surface mount layer, if both diodes D1 and D2 are conducting, the magnetoelectric dipole structure formed by the top surface mount layer, bias line layer, and vias can be considered equivalent to a magnetic conductor. If both diodes D1 and D2 are off, the magnetoelectric dipole structure formed by the top surface mount layer, bias line layer, and vias can be considered equivalent to an electrical conductor. The electromagnetic waves reflected by these two equivalent structures have a 180-degree phase difference, thus achieving a 180-degree phase difference for reflected electromagnetic waves. For transmission, when diode D1 is conducting and diode D2 is off, or diode D1 is off and diode D2 is conducting, the electromagnetic wave is received and converted into a guided wave that propagates from the middle via to the bottom surface mount layer. The transmitted electromagnetic wave has a 180-degree phase difference. When an electromagnetic wave is incident from the bottom substrate layer, it is received and propagates to the top substrate layer through vias. When both diodes D1 and D2 are conducting, it can be considered equivalent to a short circuit; when both diodes D1 and D2 are off, it can be considered equivalent to an open circuit. According to transmission line theory, the reflected electromagnetic waves from open and short circuits have a 180-degree phase difference. For transmission, when diode D1 is conducting and diode D2 is off, or vice versa, the electromagnetic wave is received and converted into a guided wave that propagates from the middle via to the top substrate layer, achieving a 180-degree phase difference in the transmitted electromagnetic wave. The omnidirectional metasurface unit of this invention can control the incident electromagnetic waves in both the top and bottom layers, thereby achieving control over omnidirectionally incident electromagnetic waves.

[0009] Preferably, when both diodes D1 and D2 are off or both diodes D1 and D2 are on, the omnidirectional metasurface unit operates in reflection mode, and the reflected electromagnetic waves have a 180-degree phase difference. When diode D1 is on and diode D2 is off or diode D1 is off and diode D2 is on, the omnidirectional metasurface unit operates in transmission mode, and the transmitted electromagnetic waves have a 180-degree phase difference.

[0010] This invention only requires the integration of two diodes, has a simple structure, and makes full use of all the states of the diodes, with no state redundancy.

[0011] Preferably, when electromagnetic waves are incident from the top patch layer, and both diodes D1 and D2 are turned on, the magnetoelectric dipole structure formed by the top patch layer, the bias line layer, and the via is equivalent to a magnetic conductor. When both diodes D1 and D2 are turned off, the magnetoelectric dipole structure formed by the top patch layer, the bias line layer, and the via is equivalent to an electrical conductor. The electromagnetic waves reflected by the two equivalent bodies have a phase difference of 180 degrees.

[0012] Preferably, the bottom patch layer includes a second intermediate patch layer, a second left patch layer, and a second right patch layer. The second intermediate patch layer is connected to the first intermediate patch layer through a via, and the second left patch layer and the second right patch layer are respectively connected to the ground layer through vias. The second right patch layer is connected to the second intermediate patch layer.

[0013] Preferably, both the first dielectric layer and the second dielectric layer are made of F4B material with a dielectric constant of 3.5 and a thickness of 3 mm, and the PP layer is made of Rogers RO4450F material with a dielectric constant of 3.52 and a thickness of 0.2 mm.

[0014] The present invention also provides an omnidirectional metasurface, including the omnidirectional metasurface unit based on the magnetoelectric dipole, wherein a plurality of the omnidirectional metasurface units are arranged in an M×N array, and the omnidirectional metasurface operates in total reflection mode, total transmission mode, or simultaneous reflection and transmission of electromagnetic waves mode.

[0015] Preferably, when the omnidirectional metasurface operates in a mode that simultaneously reflects and transmits electromagnetic waves, the arrangement of the omnidirectional metasurface units operating in the reflection mode and the omnidirectional metasurface units operating in the transmission mode adopts a checkerboard distribution or is distributed through a particle swarm optimization algorithm.

[0016] Preferably, within a radius of 9ρ, the omnidirectional metasurface unit operates in transmission mode, and the omnidirectional metasurface unit outside the radius of 9ρ operates in reflection mode. By adjusting the size of the radius 9ρ, the transmission direction is amplitude-modulated in the case of main transmission, where ρ is the side length of the omnidirectional metasurface unit.

[0017] Unlike traditional transmissive and reflective metasurfaces, the omnidirectional metasurface of this invention can simultaneously reflect and transmit electromagnetic waves. In the case of main transmission, some units can operate in reflection mode, ultimately playing a role in amplitude modulation in the transmission direction. This characteristic enables the array to have a higher controllability when generating vortex beams.

[0018] Preferably, the omnidirectional metasurface generates a vortex beam, and the phase of the (m,n)th unit in the array... This can be expressed by formula (1):

[0019]

[0020] In formula (1), λ is the wavelength, and rf mn Let be the distance between the (m,n)th element in the array and the feed source, f be the distance between the array center and the feed source, l be the order of the vortex wave, and x and y be the coordinates of the (m,n)th element in the array. It is the phase constant, with a value ranging from 0 degrees to 180 degrees.

[0021] Preferably, by substituting different phase constants Different phase distributions were obtained. The far-field radiation pattern is obtained, and then the purity of the corresponding vortex beam mode is calculated from the far-field radiation pattern. The phase constant at which the purity value is maximized is found. The far-field radiation pattern is calculated using the following formula:

[0022]

[0023] In formula (3), This is the far-field radiation pattern. For beam direction, Let be the pattern vector function of the (m,n)th cell in the array. For the element excitation vector function, Let be the position vector of the (m,n)th unit in the array. In formulas (4) and (5), It is a unit pattern vector function Simplified to a scalar function representation, I(m,n) is the element excitation vector function. Simplified to scalar function representation, qe and qf are the pattern power factors of the element and feed, respectively, k is the wavenumber, and rf is the wavenumber. mn Let |T| be the distance between the (m,n)th cell in the array and the feed source. m,n | represents the amplitude of transmission or reflection of the (m,n)th unit in the array. Let θ be the phase of the (m,n)th cell in the array. Let θ be two angles in a polar coordinate system.f (m,n) represents the angle of the (m,n)th element in the array relative to the feed source, and M and N represent the number of rows and columns of the omnidirectional metasurface elements in the array, respectively. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an existing omnidirectional metasurface, in which, Figure 1 (a) is a double-layer design. Figure 1 (b) is an omnidirectional metasurface unit with a shared aperture. Figure 1 (c) An omnidirectional metasurface unit for an improved receiver-retransmit structure;

[0025] Figure 2 An exploded view of an omnidirectional metasurface unit based on a magnetoelectric dipole, provided in Embodiment 1 of the present invention;

[0026] Figure 3 A top view of an omnidirectional metasurface unit based on a magnetoelectric dipole provided in Embodiment 1 of the present invention;

[0027] Figure 4 A side view of an omnidirectional metasurface unit based on a magnetoelectric dipole provided in Embodiment 1 of the present invention;

[0028] Figure 5 The simulation results of the omnidirectional metasurface unit based on the magnetoelectric dipole provided in Embodiment 1 of the present invention are shown in the figure. Figure 5 (a) shows the amplitude and phase of the reflected electromagnetic wave when it is incident from the top layer. Figure 5 (b) shows the amplitude and phase of the reflected electromagnetic wave when it is incident from the bottom layer. Figure 5 (c) shows the transmission amplitude and phase of the electromagnetic wave when it is incident from the top layer. Figure 5 (d) represents the transmission amplitude and phase of the electromagnetic wave when it is incident from the bottom layer.

[0029] Figure 6 This is a comparison chart of test and simulation results for the generation of unidirectional vortex waves by an omnidirectional metasurface, provided in Embodiment 2 of the present invention. Figure 6 (a)-(d) are the phase codes used in simulation and experimental testing. Figure 6 (a) and 6(b) are transmission coding arrays. Figure 6 (c) and (d) are reflection-coded arrays. Figure 6 (e)-(l) represent the test results for the corresponding phase codes, which are the test results for amplitude and phase, respectively. Figure 6 (m)-(t) represents the corresponding simulation results. Figure 6 (u)-(s) represents the purity of the generated vortex beam;

[0030] Figure 7This is a comparison chart of test and simulation results for the generation of bidirectional vortex waves by an omnidirectional metasurface, provided in Embodiment 2 of the present invention. Figure 7 (a) shows the transmission and reflection units in the array arranged in a checkerboard pattern. Figure 7 (b)-7(c) represent the purity of the vortex waves generated on the transmission and reflection sides. Figure 7 (d), 7(e), 7(h), and 7(i) represent the experimentally measured amplitude and phase results of the vortex wave. Figure 7 (f), 7(g), 7(j), and 7(k) are the corresponding simulation results;

[0031] Figure 8 This is a test comparison diagram of omnidirectional metasurface unidirectional beam focusing provided in Embodiment 2 of the present invention, wherein... Figure 8 (a)-8(c) are the reflection phase codes used in the test. Figure 8 (g)-8(i) represents the transmission phase encoding; the following are the preset focal points. Figure 8 (d)-8(f), Figure 8 (j)-8(l) represents the corresponding test results;

[0032] Figure 9 The test comparison diagram of omnidirectional metasurface bidirectional beam focusing provided in Embodiment 2 of the present invention, wherein, Figure 9 (a), 9(d), and 9(g) are the optimized transmission and reflection phase codes. Figure 9 (b) Figure 9 (c) Figure 9 (e) Figure 9 (f) Figure 9 (h) Figure 9 (i) shows the test results for the corresponding coded reflection side (R side) and transmission side (T side);

[0033] Figure 10 The simulated electric field distribution diagram of the omnidirectional metasurface unit based on the magnetoelectric dipole provided in Embodiment 1 of the present invention, wherein, Figure 10 (a)-10(d) are the electric field distribution diagrams when the electromagnetic wave is incident from the top layer, and the cell state is 00, 11, 10, and 01, respectively. Figure 10 (e)-10(h) are the electric field distribution diagrams when the electromagnetic wave is incident from the bottom layer, and the unit state is 00, 11, 10, and 01, respectively.

[0034] Figure 11 The simulated current distribution diagram of the omnidirectional metasurface unit based on the magnetoelectric dipole provided in Embodiment 1 of the present invention, wherein, Figure 11 (a)-11(d) are surface current distribution diagrams when electromagnetic waves are incident from the top layer, with the cell state at 00, 11, 10, and 01, respectively. Figure 11(e)-11(h) are surface current distribution diagrams when electromagnetic waves are incident from the bottom layer, with the cell state being 00, 11, 10, and 01, respectively.

[0035] Figure 12 Different phase constants of the omnidirectional metasurface provided in Embodiment 2 of the present invention The purity of the next first-order vortex beam;

[0036] Figure 13 A schematic diagram illustrating the improvement of vortex wave purity using omnidirectional metasurface amplitude modulation control as provided in Embodiment 2 of the present invention;

[0037] Figure 14 This is a schematic diagram of the operation of the omnidirectional metasurface provided in Embodiment 2 of the present invention;

[0038] In the diagram: 10 Top surface mount layer, 11 First intermediate surface mount layer, 12 First left surface mount layer, 13 First right surface mount layer, 20 First dielectric layer, 30 Bias line layer, 40 PP layer, 50 Ground layer, 60 Second dielectric layer, 70 Bottom surface mount layer, 71 Second intermediate surface mount layer, 72 Second left surface mount layer, 73 Second right surface mount layer. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1

[0041] like Figure 2-4 As shown, this embodiment provides an omnidirectional metasurface unit based on a magnetoelectric dipole, including a top patch layer 10, a first dielectric layer 20, a bias line layer 30, a PP layer 40, a ground layer 50, a second dielectric layer 60, and a bottom patch layer 70 arranged sequentially from top to bottom. The top patch layer 10 integrates diodes D1 and D2. The top patch layer 10 includes a first intermediate patch layer 11, a first left patch layer 12, and a first right patch layer 13. The anode of diode D1 is connected to the first left patch layer 12, and the cathode of diode D1 is connected to the first intermediate patch layer 11. The anode of diode D2 is connected to the first right patch layer 13, and the cathode of diode D2 is connected to the first intermediate patch layer 11. The first intermediate patch layer 11 is connected to the bottom patch layer 70 through a via. The first left patch layer 12 and the first right patch layer 13 are respectively connected to the bias line layer 30 through vias. The bottom patch layer 70 is connected to the ground layer 50 through vias.

[0042] In the structure of the omnidirectional metasurface, the top patch layer 10, the bias line layer 30 and the via together constitute a magnetoelectric dipole structure, and the bottom patch layer 70, the ground layer 50 and the via also constitute a magnetoelectric dipole structure. The design based on the magnetoelectric dipole structure enables the omnidirectional metasurface to have broadband characteristics. The top surface mount layer 10 integrates diodes D1 and D2. By adjusting the voltage of the first left surface mount layer 12 and the first right surface mount layer 13, the switching on and off of diodes D1 and D2 can be controlled. When electromagnetic waves are incident from the top surface mount layer 10, and both diodes D1 and D2 are conducting, the magnetoelectric dipole structure formed by the top surface mount layer 10, the bias line layer 30, and the via can be equivalent to a magnetic conductor. When both diodes D1 and D2 are off, the magnetoelectric dipole structure formed by the top surface mount layer 10, the bias line layer 30, and the via can be equivalent to an electrical conductor. The electromagnetic waves reflected by these two equivalent bodies have a 180-degree phase difference, which can realize the reflection of electromagnetic waves with a 180-degree phase difference. When diode D1 is on and diode D2 is off, or diode D1 is off and diode D2 is on, the electromagnetic wave incident from the top surface mount layer is received and converted into a guided wave that propagates from the middle via to the bottom surface mount layer 70. By controlling diode D1 to be on and diode D2 to be off, or diode D1 to be off and diode D2 to be on, the direction of the current can be controlled, thereby achieving a 180-degree phase difference of the transmitted electromagnetic wave.

[0043] When an electromagnetic wave is incident from the bottom surface mount layer 70, it is received and propagates through the via to the top surface mount layer 10. When both diodes D1 and D2 are conducting, it can be considered equivalent to a short circuit; when both diodes D1 and D2 are off, it can be considered equivalent to an open circuit. According to transmission line theory, the reflected electromagnetic waves from open and short circuits have a 180-degree phase difference. When diode D1 is conducting and diode D2 is off, or diode D1 is off and diode D2 is conducting, when an electromagnetic wave is incident from the bottom surface mount layer 70, it is received and converted into a guided wave that propagates through the intermediate via to the top surface mount layer 10. By controlling whether diode D1 is conducting or diode D2 is off, or diode D1 is off and diode D2 is conducting, the direction of the current can be controlled, thereby achieving a 180-degree phase difference in the transmitted electromagnetic wave. Therefore, the omnidirectional metasurface unit of this invention can achieve the control of incident electromagnetic waves in both the top and bottom directions, thus realizing the control of omnidirectional incident electromagnetic waves.

[0044] It should be noted that, for transmission, when electromagnetic waves are incident from the top patch layer 10 and the bottom patch layer 70, there is a 180-degree phase difference between the transmitted electromagnetic waves. This is because, when electromagnetic waves are incident from the top patch layer 10, if diode D1 is on and diode D2 is off, or if diode D1 is off and diode D2 is on, the current in the omnidirectional metasurface unit is opposite when receiving electromagnetic waves, and the 180-degree phase difference occurs during reception. When electromagnetic waves are incident from the bottom patch layer 70, if diode D1 is on and diode D2 is off, or if diode D1 is off and diode D2 is on, the current in the omnidirectional metasurface unit is in phase when receiving electromagnetic waves, i.e., there is no phase difference. When transmitting electromagnetic waves, the currents in the two states are opposite, and the 180-degree phase difference occurs during reflection.

[0045] Continue reading Figure 2 The bottom patch layer 70 includes a second intermediate patch layer 71, a second left patch layer 72, and a second right patch layer 73. The second intermediate patch layer 71 is connected to the first intermediate patch layer 11 via vias. The second left patch layer 72 is connected to the ground layer 50 via vias. The second right patch layer 73 is connected to the ground layer 50 via vias, and the second right patch layer 73 is connected to the second intermediate patch layer 71. The position of the vias needs to be close to the center according to the structural design of the magnetoelectric dipole. The size of the vias is optimized through simulation software to meet the actual processing conditions.

[0046] The first dielectric layer 20 and the second dielectric layer 60 are both made of F4B material with a dielectric constant of 3.5 and a thickness of 3 mm. The PP layer 40 is made of Rogers RO4450F material with a dielectric constant of 3.52 and a thickness of 0.2 mm.

[0047] When both diodes D1 and D2 are off, or both diodes D1 and D2 are on, the omnidirectional metasurface unit operates in reflection mode, and the reflected electromagnetic wave has a 180-degree phase difference. When diode D1 is on and diode D2 is off, or diode D1 is off and diode D2 is on, the omnidirectional metasurface unit operates in transmission mode, and the transmitted electromagnetic wave has a 180-degree phase difference. Compared to existing omnidirectional metasurface structures that integrate at least three diodes, this invention only requires the integration of two diodes, resulting in a simpler structure that fully utilizes all diode states without state redundancy.

[0048] Diodes D1 and D2 are model MADP-000907-14020 (MACOM), which are gallium arsenide (GaAs) devices with high switching speed. This invention uses a microcontroller unit (MCU) to control the states of diodes D1 and D2 in the omnidirectional metasurface unit. The states of the two diodes can be defined by a two-bit binary number, represented as 00, 01, 10, and 11. When both diodes D1 and D2 are on, the state is 11; when both are off, the state is 00; when D1 is on and D2 is off, the state is 10; and when D1 is off and D2 is on, the state is 01. In this embodiment, the anode control voltage of diode D1 is V1, and the anode control voltage of diode D2 is V2. Table 1 illustrates the four states of the two diodes.

[0049] Table 1 Relationship between control voltage and state of omnidirectional metasurface unit

[0050] States (PIN1, PIN2) V1 = 3.3V V1 = 0V V2 = 3.3V 11 01 V2 = 0V 10 00

[0051] Working principle: such as Figure 10 and Figure 11 As shown, the electric field and current distributions of the omnidirectional metasurface in different states are presented respectively. Figure 10 (a) and Figure 10 As shown in (b), when electromagnetic waves are incident from the top patch layer 10, and the omnidirectional metasurface unit operates in states 00 and 11, the electric field energy is mainly distributed in the structure above the ground layer 50, such as... Figure 10 (e) and Figure 10As shown in (f), when an electromagnetic wave is incident from the bottom patch layer 70 and the omnidirectional metasurface unit is operating in states 00 and 11, the electric field energy is distributed throughout the entire omnidirectional metasurface unit structure. The above results reveal that when the omnidirectional metasurface unit is operating in states 00 and 11, the principle that causes the reflected electromagnetic wave to have a 180-degree phase difference between the two states when the electromagnetic wave is incident from the top and bottom layers is different. When an electromagnetic wave is incident from the top surface mount layer 10, and both diodes D1 and D2 are conducting, the magnetoelectric dipole structure formed by the top surface mount layer 10, bias line layer 30, and vias can be equivalent to a magnetic conductor. When both diodes D1 and D2 are off, the magnetoelectric dipole structure formed by the top surface mount layer 10, bias line layer 30, and vias can be equivalent to an electrical conductor. These two different equivalent structures are due to the transformation of the imaginary impedance. When the imaginary impedance approaches infinity, it is equivalent to a perfect magnetic conductor, and the phase of the reflected electromagnetic wave is 0°. When the imaginary impedance approaches 0, it is equivalent to a perfect electrical conductor, and the phase of the reflected electromagnetic wave is 180°. Although the imaginary impedance of the structure changes with frequency, the phase difference of the reflected wave will approach 180°. When an electromagnetic wave is incident from the bottom surface mount layer 70, it is received and propagates to the top surface mount layer 10 through a via. At this time, when both diodes D1 and D2 are conducting, it can be equivalent to a short circuit. When both diodes D1 and D2 are turning off, it can be equivalent to an open circuit. According to transmission line theory, the electromagnetic waves reflected by open circuits and short circuits have a phase difference of 180 degrees.

[0052] It is worth noting that, although Figure 10 In figures (e) and (f), the electric field energy is also distributed in the top layer, but the energy is not radiated outwards. This can be seen intuitively from the figures because the electric field distribution in the top layer is almost symmetrical and the electric fields are opposite, which causes the energy not to radiate outwards.

[0053] The principle that there is a 180° phase difference between different states of a unit can be... Figure 11 The current distribution diagram can be seen intuitively. Figure 11 Figures (c) and (d) show the current distribution when electromagnetic waves are incident from the top layer and the unit is operating in states 01 and 10. Figure 11 (g) and (h) show the current distribution when electromagnetic waves are incident from the bottom layer and the cell is operating in states 01 and 10. Figure 11 (c), (d) and Figure 11 The most significant difference between (g) and (h) is that... Figure 11 When the electromagnetic waves incident from the top layer are converted into current in units (c) and (d), the current in the top layer is in the opposite direction. Figure 11When the elements in (g) and (h) radiate electromagnetic waves, the current is also reversed. This reverse current results in the radiated electromagnetic waves having a 180° phase difference between the two operating states. The simulation results of the omnidirectional metasurface element show that the beam has a phase difference of nearly 180° between the two states in the frequency range of 13GHz-17GHz.

[0054] Example 2

[0055] See Figure 14 Based on Example 1, this example provides an omnidirectional metasurface, including the omnidirectional metasurface unit based on magnetoelectric dipoles of Example 1. Multiple omnidirectional metasurface units are arranged in an M×N array. In this example, the omnidirectional metasurface is arranged in a 16×16 array. When all omnidirectional metasurface units are operating in reflection mode, the omnidirectional metasurface operates in total reflection mode. When all omnidirectional metasurface units are operating in transmission mode, the omnidirectional metasurface operates in total transmission mode. When some omnidirectional metasurface units in the array are operating in reflection mode and some are operating in transmission mode, the omnidirectional metasurface can simultaneously reflect and transmit electromagnetic waves.

[0056] When an omnidirectional metasurface operates in a mode that simultaneously reflects and transmits electromagnetic waves, the omnidirectional metasurface units (reflection units) operating in the reflection mode and the omnidirectional metasurface units (transmission units) operating in the transmission mode are arranged in a checkerboard pattern. In addition to the checkerboard pattern, particle swarm optimization algorithms can also be used to arrange the reflection and transmission units.

[0057] It should be noted that, unlike traditional transmissive and reflective metasurfaces, the omnidirectional metasurface of this invention can simultaneously reflect and transmit electromagnetic waves, such as... Figure 13 As shown, within the radius R = 9ρ, where ρ is the size of the omnidirectional metasurface unit (in this embodiment, the side length ρ of the omnidirectional metasurface unit is equal to 10 mm), the omnidirectional metasurface unit operates in transmission mode, while the omnidirectional metasurface units outside the radius R operate in reflection mode. By adjusting the size of the radius R, some units can operate in reflection mode while maintaining primary transmission, ultimately achieving amplitude modulation in the transmission direction. This characteristic allows the array to have a higher degree of control when generating vortex beams.

[0058] The omnidirectional metasurface also includes a feed source, which is 160mm away from the array during testing. In this embodiment, a horn feed is used, and the feeding method is horn feeding. CST Microwave Studio software is used to simulate and verify the array's performance. The simulation demonstrates the array's vortex wave generation and beam focusing performance. The omnidirectional metasurface generates a vortex beam, and the phase of the (m,n)th element in the array... This can be expressed by formula (1):

[0059]

[0060] In formula (1), λ is the wavelength, and rf mn Let be the distance between the (m,n)th element in the array and the feed source, f be the distance between the array center and the feed source, l be the order of the vortex wave, and x and y be the coordinates of the (m,n)th element in the array. This is the phase constant.

[0061] The phase of the (m,n)th element in the calculated array It is a continuous phase. Since the design uses 1-bit phase, the continuous phase needs to be quantized using formula (2).

[0062]

[0063] Ψ mn The discrete phase, Let be the phase of the (m,n)th unit in the array. It is a continuous phase that needs to be discretized. round is a rounding function. The discretized phase has only 0 and π, which are radian values ​​and can be converted to angle values ​​of 0° and 180°.

[0064] By optimizing the phase constant The value of can optimize the purity of vortex waves generated by omnidirectional metasurfaces. The specific method is as follows:

[0065]

[0066] In formula (3), The calculated far-field radiation pattern. For beam direction, Let be the pattern vector function of the (m,n)th cell in the array. For the element excitation vector function, Let be the position vector of the (m,n)th unit in the array. In formulas (4) and (5), It is a unit pattern vector function Simplified to a scalar function representation, I(m,n) is the element excitation vector function. Simplified to scalar function representation, qe and qf are the pattern power factors of the element and feed, respectively, which can be obtained by fitting the patterns of the element and feed horn antennas. k is the wave number, and rf... mn Let |T| be the distance between the (m,n)th cell in the array and the feed source. m,n | represents the amplitude of transmission or reflection of the (m,n)th unit in the array. Let θ be the phase of the (m,n)th cell in the array. Let θ be two angles in a polar coordinate system. f(m,n) represents the angle of the (m,n)th cell in the array relative to the feed source.

[0067] By substituting different phase constants The value ranges from 0 degrees to 180 degrees, which can yield different phase distributions. The far-field radiation pattern is obtained, and then the purity of the corresponding vortex beam mode is calculated from the far-field radiation pattern to find the value when the purity is maximized. This is the final result. Figure 12 Different phase constants of omnidirectional metasurfaces The purity of the first-order vortex beam is given by Cla., where Cla. represents the calculated result and Sim. represents the simulation result. The horizontal axis represents the order and the vertical axis represents the mode purity.

[0068] The phase distribution for beam focusing using an omnidirectional metasurface is calculated using formula (6):

[0069]

[0070] In formula (6), The phase compensation obtained is a continuous phase, which can also be quantized using formula (2).

[0071] Simulation test

[0072] The omnidirectional metasurface unit was simulated to verify the effectiveness of the design. CST Micro Wave Studio software was used to simulate and verify the performance of the omnidirectional metasurface unit, using periodic boundary conditions, and the diodes were adopted as equivalent RLC series circuits. Figure 5 The figure shows the simulation results of the omnidirectional metasurface unit based on the magnetoelectric dipole. Figure 5 (a) shows the amplitude and phase of the reflected electromagnetic wave when it is incident from the top layer. Figure 5 (b) shows the amplitude and phase of the reflected electromagnetic wave when it is incident from the bottom layer. Figure 5 (c) shows the transmission amplitude and phase of the electromagnetic wave when it is incident from the top layer. Figure 5 (d) represents the transmission amplitude and phase of the electromagnetic wave when it is incident from the bottom layer. Due to the reciprocity theorem, Figure 5 (d) shows the electromagnetic wave incident from the bottom layer and Figure 5 (c) shows an electromagnetic wave incident from the top layer, with both its transmission amplitude and phase being consistent.

[0073] Figure 6 A comparison of test and simulation results for generating unidirectional vortex waves on an omnidirectional metasurface, in which... Figure 6 (a)-(d) are the phase codes used in simulation and experimental testing. Figure 6 (a) and 6(b) are transmission coding arrays. Figure 6 (c) and (d) are reflection-coded arrays. Figure 6 (b)-(l) represent the test results for the corresponding phase codes, which are the test results for amplitude and phase, respectively. Figure 6 (m)-(t) represents the corresponding simulation results. Figure 6 (u)-(s) represents the purity of the generated vortex beam. Both simulations and tests used results from 15 GHz.

[0074] Figure 7 A comparison of test and simulation results for generating bidirectional vortex waves on an omnidirectional metasurface. Figure 7 (a) shows the transmission and reflection units in the array arranged in a checkerboard pattern. Figure 7 (b)-7(c) represent the purity of the vortex waves generated on the transmission and reflection sides. Figure 7 (d), 7(e), 7(h), and 7(i) represent the experimentally measured amplitude and phase results of the vortex wave. Figure 7 (f), 7(g), 7(j), and 7(k) are the corresponding simulation results. Both the simulation and the test used results from 15 GHz.

[0075] Figure 8 The images show a comparison of tests on unidirectional beam focusing of omnidirectional metasurfaces. Figure 8 (a)-8(c) are the reflection phase codes used in the test. Figure 8 (g)-8(i) is the transmission phase code, and the following is the preset focus point. Figure 8 (d)-8(f), Figure 8 (j)-8(l) represent the corresponding test results. Both simulation and testing used results from 15GHz.

[0076] Figure 9 The images show a comparison of test results for bidirectional beam focusing on an omnidirectional metasurface. Figure 9 (a), 9(d), and 9(g) are the optimized transmission and reflection phase codes. The text below is the preset reflection focal point (R point) and transmission focal point (T point). Figure 9 (b) Figure 9 (c) Figure 9 (e) Figure 9 (f) Figure 9 (h) Figure 9 (i) shows the test results for the corresponding coded reflection side (R side) and transmission side (T side). Both simulation and testing used results from 15 GHz.

[0077] Figure 10 The simulated electric field distribution diagram of the omnidirectional metasurface unit based on the magnetoelectric dipole provided in Embodiment 1 of the present invention, wherein, Figure 10(a)-10(d) are the electric field distribution diagrams when the electromagnetic wave is incident from the top layer, and the cell state is 00, 11, 10, and 01, respectively. Figure 10 (e)-10(h) are the electric field distribution diagrams when the electromagnetic wave is incident from the bottom layer, and the unit state is 00, 11, 10, and 01, respectively.

[0078] Figure 11 The simulated current distribution diagram of the omnidirectional metasurface unit based on the magnetoelectric dipole provided in Embodiment 1 of the present invention, wherein, Figure 11 (a)-11(d) are surface current distribution diagrams when electromagnetic waves are incident from the top layer, with the cell state being 00, 11, 10, and 01, respectively. Figure 11 (e)-11(h) are surface current distribution diagrams when electromagnetic waves are incident from the bottom layer, with the cell state being 00, 11, 10, and 01, respectively.

[0079] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An omnidirectional metasurface unit based on a magnetoelectric dipole, characterized in that: The omnidirectional metasurface includes, from top to bottom, a top patch layer (10), a first dielectric layer (20), a bias line layer (30), a PP layer (40), a ground layer (50), a second dielectric layer (60), and a bottom patch layer (70), the top patch layer (10) integrates diode D1 and diode D2, the top patch layer (10) includes a first middle patch layer (11), a first left patch layer (12), and a first right patch layer (13), the anode of diode D1 is connected to the first left patch layer (12), the cathode of diode D1 is connected to the first middle patch layer (11), the anode of diode D2 is connected to the first right patch layer (13), the cathode of diode D2 is connected to the first middle patch layer (11), the first middle patch layer (11) is connected to the bottom patch layer (70) through a via, the first left patch layer (12) and the first right patch layer (13) are respectively connected to the bias line layer (30) through vias, and the bottom patch layer (70) is connected to the ground layer (50) through a via; when electromagnetic waves are incident from the top patch layer (10), the top patch layer (10), the bias line layer (30), and the via collectively constitute a magneto-electric dipole structure equivalent to a magnetic conductor when diode D1 and diode D2 are both turned on, and the magneto-electric dipole structure collectively constitutes an electric conductor when diode D1 and diode D2 are both turned off, and the electromagnetic waves reflected by the two equivalent bodies have a phase difference of 180 degrees.

2. The magnetic-electric dipole based omnidirectional metasurface unit of claim 1, wherein: When diode D1 and diode D2 are both turned off or turned on, the omnidirectional metasurface unit works in a reflection mode, and the reflected electromagnetic waves have a phase difference of 180 degrees; when diode D1 is turned on and diode D2 is turned off, or diode D1 is turned off and diode D2 is turned on, the omnidirectional metasurface unit works in a transmission mode, and the transmitted electromagnetic waves have a phase difference of 180 degrees.

3. The magnetic-electric dipole based omnidirectional metasurface unit of claim 1, wherein: The bottom patch layer (70) includes a second middle patch layer (71), a second left patch layer (72), and a second right patch layer (73), the second middle patch layer (71) is connected to the first middle patch layer (11) through a via, the second left patch layer (72) and the second right patch layer (73) are respectively connected to the ground layer (50) through vias, and the second right patch layer (73) is connected to the second middle patch layer (71).

4. The magnetic-electric dipole based omnidirectional metasurface unit of claim 1, wherein: The first dielectric layer (20) and the second dielectric layer (60) are both made of F4B material with a dielectric constant of 3.5 and a thickness of 3 mm, and the PP layer (40) is made of Rogers RO4450F material with a dielectric constant of 3.52 and a thickness of 0.2 mm.

5. An omnidirectional metasurface comprising the magnetic-electric dipole based omnidirectional metasurface unit of any one of claims 1-4, characterized in that: Multiple omnidirectional metasurface units in M × N The array arrangement allows the omnidirectional metasurface to operate in total reflection mode, total transmission mode, or simultaneous reflection and transmission of electromagnetic waves.

6. The metasurface of claim 5, wherein: When the omnidirectional metasurface works in a mode of simultaneously reflecting and transmitting electromagnetic waves, the omnidirectional metasurface units working in the reflection mode and the omnidirectional metasurface units working in the transmission mode are distributed in a chessboard pattern or through a particle swarm optimization algorithm.

7. The metasurface of claim 6, wherein: Within a radius of the omnidirectional metasurface unit works in transmission mode, outside the radius the omnidirectional metasurface unit works in reflection mode, by adjusting the size of the radius , the transmission direction is amplitude modulated in the main transmission case, is the side length of the omnidirectional metasurface unit.

8. The metasurface of claim 5, wherein: The metasurface produces a vortex beam, the phase of the (m, n)th element in the array is is expressed by formula (1): （1） In formula (1), is the wavelength, is the distance between the (m, n)th element in the array and the feed, f is the distance between the center of the array and the feed, l is the order of the vortex wave, x and y is the coordinate of the (m, n)th element in the array, is the phase constant, which ranges from 0 degrees to 180 degrees.

9. The metasurface of claim 8, wherein: By substituting different phase constants , the far-field radiation patterns under different phase distributions are obtained, and the purity of the corresponding vortex beam mode is calculated from the far-field radiation pattern to find the phase constant with the maximum purity value, and the far-field radiation pattern is calculated by the following formula: （3） （4） （5） In equation (3), is the far-field radiation pattern, is the beam pointing, is the (m, n)th element directional pattern vector function in the array, is the element excitation vector function, is the position vector of the (m, n)th element in the array, in equations (4) and (5), is the element directional pattern vector function is simplified to a scalar function representation, I m , n is the element excitation vector function is simplified to a scalar function representation, qe and qf are the directional pattern power factors of the element and the feed, respectively, k is the wave number, is the distance between the (m, n)th element and the feed in the array, is the amplitude of the (m, n)th element in the array to transmit or reflect, is the phase of the (m, n)th element in the array, and are two angles in the spatial polar coordinate system, is the angle of the (m, n)th element in the array relative to the feed, M N represent the number of rows and columns of the omnidirectional metasurface elements in the array, respectively.​​

Images