MOS-switched gain mmwave programmable metasurface

Abstract

The application discloses a MOS switch regulated gain millimeter wave programmable metasurface and belongs to the field of novel artificial electromagnetic materials. The structure realizes a reflective metasurface unit of an integrated power amplifier and a MOS switch chip, realizes x-polarized wave receiving in a high-isolation dual-polarized rectangular patch antenna unit structure, and radiates y-polarized wave after microstrip transmission amplification, and the y-polarized reflection phase can be changed by adjusting the on-off of the MOS switch chip, which makes it possible to ensure signal active amplification while having good 1bit effect, thereby realizing the coding state switching of the metasurface unit and the far-field beam regulation of the metasurface array. The application is a millimeter wave artificial electromagnetic surface with an active amplification function, and is expected to solve the problems of path loss and reflection loss existing in the current reflective metasurface and the problem of radio frequency signal leakage caused by the bias circuit of the programmable metasurface, and has important potential applications in the fields of intelligent communication, imaging and computing technology.

Description

Technical Field

[0001] This invention relates to the field of novel artificial electromagnetic materials technology, and in particular to a gain millimeter-wave programmable metasurface that can be controlled by a MOS switch. Background Technology

[0002] Metamaterials are artificial materials that allow for flexible manipulation of electromagnetic waves by arranging subwavelength-scale structural units periodically or aperiodically. Artificial electromagnetic surfaces (metamaterials) are two-dimensional structures developed from novel three-dimensional artificial electromagnetic materials (metamaterials). For such two-dimensional artificial electromagnetic surfaces, each unit can be independently designed, allowing each unit to independently control the amplitude and phase of electromagnetic waves, thus obtaining more complex field distributions. Based on this discontinuity in phase or amplitude, the units can be discretized into a finite number of types and described using digital codes, also known as digitally coded metamaterials. For example, if two units have a 180° difference in reflection phase but similar amplitudes, they can be encoded with "0" and "1". With continuous technological advancements, digitally coded metamaterials can be extended to 2-bit and even multi-bit encoding, further enhancing the diversity and richness of their applications.

[0003] Existing PIN diode-based modulation schemes have significant technical limitations, requiring the introduction of bias circuit networks into the RF link, which significantly increases RF signal leakage. Meanwhile, path loss and reflection loss issues in current high-frequency reflective metasurfaces limit their signal coverage and communication applications. Summary of the Invention

[0004] This invention provides a MOS switch-controlled gain millimeter-wave programmable metasurface, which is a millimeter-wave artificial electromagnetic surface with active amplification function. It is expected to solve the path loss and reflection loss problems of current reflective metasurfaces, as well as the RF signal leakage problem caused by the bias circuit of the programmable metasurface. It has important potential applications in fields such as intelligent communication, imaging and computing technology.

[0005] This invention provides a gain millimeter-wave programmable metasurface controlled by a MOS switch. The metasurface is composed of a two-dimensional array of multiple subwavelength units. Each subwavelength unit includes a radiating patch (1), a microstrip RF link (2), a substrate (3), a power amplifier chip (7), a MOS switch chip (8), and a slotted metal backplate (4).

[0006] The radiation patch (1) is disposed on the top layer of the subwavelength unit and etched on the substrate.

[0007] The microstrip radio frequency link (2) is located on the bottom layer of the subwavelength unit, on the back side of the substrate.

[0008] The substrate (3) is a multilayer dielectric structure with a metal structure layer (6) between each dielectric layer;

[0009] The slotted metal backplate (4) is etched on the metal structure layer between the bottom layer and the sub-bottom layer of the dielectric, and is separated from the microstrip radio frequency link by a dielectric layer; the metal backplate is provided with three hourglass-shaped radiation slots (5), of which the vertically open radiation slot is located at the center of the backplate and is orthogonally arranged with the other two horizontally open hourglass-shaped radiation slots.

[0010] The power amplifier chip (7) and two MOS switch chips (8) are attached to the back of the substrate and bonded to the microstrip RF link by gold wire.

[0011] Optionally, in one embodiment of the present invention, the radiating patch has a rectangular structure, is made of copper, and operates at a millimeter-wave frequency.

[0012] Optionally, in one embodiment of the present invention, the substrate is a 5-layer dielectric structure of Rogers RO4350B and Rogers RO4450F overlapping, the top layer is Rogers RO4450F, the dielectric constants are 3.66 and 3.7, and the loss tangents are 0.0037 and 0.004, respectively.

[0013] Optionally, in one embodiment of the present invention, the material used for the bottom microstrip RF link and the slotted metal backplane is copper. The slotted metal backplane adopts an hourglass-shaped slot to ensure that electromagnetic energy is efficiently coupled to the bottom microstrip transmission link. After being amplified by a power amplifier, the channel is selected by a MOS switch. The two channels are respectively connected to two hourglass-shaped radiation slots orthogonal to the central slot. The two radiation slots achieve a 180° phase difference while implementing secondary radiation through an anti-phase feeding design.

[0014] Optionally, in one embodiment of the present invention, different coding arrangements are calculated according to different functional requirements, and a field-programmable gate array (FPGA) is used to programmatically control the distribution of bias voltage and reconstruct the reflection phase distribution.

[0015] The gain millimeter-wave programmable metasurface with MOS switch control according to the embodiments of the present invention has the following beneficial effects:

[0016] 1. This invention provides a gain-programmable millimeter-wave metasurface based on MOS switch control, which, compared with existing coded metasurfaces, features active amplification and reflection, electronically programmable control, and reconfigurability.

[0017] 2. The present invention uses the electromagnetic characteristics of a self-developed MOS switch chip control unit, which has advantages such as radio frequency isolation and good stability compared with the PIN diode control method.

[0018] 3. This invention extends the operating frequency of the programmable metasurface to the millimeter-wave frequency region by designing a gain-programmable metasurface unit based on MOS switch control, thus greatly expanding the controllability of millimeter waves.

[0019] 4. The method proposed in this invention is to achieve x-polarized wave reception by designing a high-isolation dual-polarized rectangular patch in a metasurface unit, and then re-radiate it as a y-polarized wave after microstrip transmission and power amplifier amplification. The y-polarized radiation phase is controlled by adjusting the on / off state of the MOS switching chip. This enables the signal to be actively amplified while achieving a good 1-bit effect. It is an active amplification and reflection unit in the millimeter-wave band, which has great innovation and feasibility.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0022] Figure 1 This is a schematic diagram of a three-dimensional structure of a MOS switch-controlled millimeter-wave programmable metasurface unit according to an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of a gain millimeter-wave programmable metasurface structure for MOS switch control according to an embodiment of the present invention;

[0024] Figure 3 (a) is a schematic diagram of the top-level structure of the unit. The unit as a whole is a square with a side length of p. The widths of the rectangular radiating patches are p1.

[0025] Figure 3 (b) is a schematic diagram of the unit's bottom layer structure, concealing the dielectric layer between the slotted metal backplate and the microstrip lines. The microstrip line lengths are l1, l2, l3, and l4, and the microstrip width is w. Space is reserved between the four microstrip sections as ports for MOS switch chips and amplifier chips. The chips are bonded to the microstrips via gold wire bonding. The dimensions of the horizontal hourglass-shaped slot and the vertical hourglass-shaped slot are a1, a2, b1, b2 and a3, a4, b3, b4, respectively.

[0026] Figure 3(c) is a schematic diagram of the unit substrate layer structure. The substrate is a 5-layer dielectric structure with RO4350B substrate and Rogers RO4450F PP layer stacked. The top layer is Rogers RO4450F. There are metal layers between each layer as control lines and power lines. The thickness of the center layer is h2, and the thickness of the remaining layers is h1. The slotted metal backplate is located between the bottom layer and the fourth layer.

[0027] Figure 4 The curves showing the reflection amplitude changes caused by two reflection states in an embodiment of the present invention without an integrated active power amplifier are shown.

[0028] Figure 5 The figures show the reflection phase change curves caused by two reflection states when the active power amplifier is not integrated in the embodiments of the present invention.

[0029] Figure 6 The curves showing the reflection amplitude variation caused by two reflection states when integrating an active power amplifier in an embodiment of the present invention are shown.

[0030] Figure 7 The curves showing the reflection phase change caused by two reflection states when integrating an active power amplifier in an embodiment of the present invention are shown.

[0031] Figure 8 The image shows a three-dimensional far-field scattering pattern of a metasurface with an encoding sequence of 0110011001 in an embodiment of the present invention, wherein the operating frequency is 30 GHz and the angle between the beam and the z-axis is 30°.

[0032] Figure 9 The image shows a three-dimensional far-field scattering pattern of a metasurface with an encoding sequence of 0111000111 in an embodiment of the present invention, wherein the operating frequency is 30 GHz and the angle between the beam and the z-axis is 20°. Detailed Implementation

[0033] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] like Figure 1 and Figure 2 As shown, the gain millimeter-wave programmable metasurface controlled by the MOS switch is composed of a two-dimensional array of multiple subwavelength units. Each subwavelength unit includes a radiating patch (1), a microstrip RF link (2), a substrate (3), a power amplifier chip (7), a MOS switch chip (8), and a slotted metal backplate (4).

[0035] The radiation patch (1) is disposed on the top layer of the subwavelength unit and etched on the substrate.

[0036] The microstrip radio frequency link (2) is located on the bottom layer of the subwavelength unit, on the back side of the substrate.

[0037] The substrate (3) is a multilayer dielectric structure with a metal structure layer (6) between each dielectric layer;

[0038] The slotted metal backplate (4) is etched on the metal structure layer between the bottom layer and the sub-bottom layer of the dielectric, and is separated from the microstrip radio frequency link by a dielectric layer; the metal backplate is provided with three hourglass-shaped radiation slots (5), of which the vertically open radiation slot is located at the center of the backplate and is orthogonally arranged with the other two horizontally open hourglass-shaped radiation slots.

[0039] The power amplifier chip (7) and two MOS switch chips (8) are attached to the back of the substrate and bonded to the microstrip RF link by gold wire.

[0040] In one embodiment of the invention, the radiating patch has a rectangular structure, is made of copper, and operates at the millimeter-wave frequency band. The patch is etched onto a multilayer substrate. The slotted metal backplate is also made of copper, which effectively suppresses the transmission of millimeter-wave electromagnetic waves, thus making it a reflective metasurface. The slotted metal backplate uses an hourglass-shaped slot to ensure efficient coupling of electromagnetic energy to the underlying microstrip transmission link. After amplification by a power amplifier, the energy is selected by a MOS switch. The two channels lead to two hourglass-shaped radiating slots orthogonal to the central slot. The two radiating slots achieve a 180° phase difference while implementing secondary radiation through an anti-phase feeding design.

[0041] The dielectric substrate is a 5-layer structure of overlapping Rogers RO4350B and Rogers RO4450F, with Rogers RO4450F as the top layer. The dielectric constants are 3.66 and 3.7, and the loss tangents are 0.0037 and 0.004, respectively. There are metal trace layers between each dielectric layer.

[0042] In one embodiment of the present invention, a programmable metasurface solution for gain control via a MOS switch is proposed. A self-developed three-port MOS switch is used as the core control element, and the on / off state is controlled by the gate voltage. Compared with the traditional PIN diode solution, it eliminates the need for additional bias circuitry in the RF link, effectively avoiding the RF bias interference problem of traditional PIN diodes. Within a preset operating frequency band, the RF transmission path is dynamically switched via the MOS switch, and two hourglass-shaped radiating slots with inverse phase feeding achieve reconfigurable radiation with 0° or 180° reflection phase.

[0043] In one embodiment of the present invention, by integrating a power amplifier in the radio frequency link, the energy loss of traditional reflective metasurfaces is effectively compensated, and an active amplification mechanism is introduced to realize a paradigm shift from passive reflection to active amplification.

[0044] In one embodiment of the present invention, different coding arrangements can be calculated according to different functional requirements, and the FPGA provides an independent control channel to drive the metasurface.

[0045] In one embodiment of the present invention, after the incident electromagnetic wave is received, it is amplified by a power amplifier. Then, by controlling the on / off state of the MOS switch, two active amplified reflected waves with similar amplitudes but 180° phase differences can be generated. This unique phase modulation characteristic enables the metasurface unit to realize two basic encoded states, "0" and "1". Electromagnetic control can be achieved by rationally designing the unit arrangement.

[0046] The metasurface unit of this invention exhibits significantly different reflection properties under different on / off states of the MOS switch. Specifically, it can reflect electromagnetic waves with similar amplitudes and a 180° phase difference within a certain frequency range, thus obtaining two encoded states, "0" and "1," which can be switched in real time. Furthermore, the unit successfully introduces an active amplification mechanism by integrating a power amplifier module into the RF link. This design effectively compensates for the energy loss of the metasurface, enabling it to possess active signal amplification capabilities. This technology may be applied in the practical engineering of programmable metasurfaces.

[0047] According to different functional requirements, the metasurface of this invention can calculate different coding arrangements. By using FPGA to program and control the distribution of bias voltage, the reconfigurable reflection phase distribution can be realized, thereby enabling flexible control of millimeter-wave beams and achieving various functions such as beam anomalous deflection and beam scanning. Therefore, it is a programmable electromagnetic metasurface.

[0048] like Figure 3As shown in (a), (b), and (c), the structure of a gain-controlled millimeter-wave programmable metasurface with MOS switch is illustrated. Its structure mainly consists of a radiating patch, microstrip transmission lines, a MOS switch, a power amplifier chip, a substrate, and a slotted metal backplate. The top radiating patch of this invention has a rectangular structure, operates at millimeter-wave frequencies, is made of copper, and has a thickness of 18 micrometers. The dielectric substrate is a stacked structure comprising a Rogers RO4350B substrate and a Rogers RO4450F PP layer. From the top layer to the metal backplate, it is specifically divided into a 100µm Rogers RO4450F PP layer, a 100µm Rogers RO4350B substrate, a 200µm Rogers RO4450F PP layer, and a 100µm Rogers RO4350B substrate. Between each layer is a 35µm metal layer made of copper, serving as the control and power line routing layers. The slotted metal backplane and the last layer of microstrip RF links are separated by a 100um Rogers RO4450F layer. The microstrip is 18um thick and is used for RF transmission. The metal backplane is made of copper and is 35 micrometers thick, which can effectively suppress the transmission of millimeter-wave electromagnetic waves. Therefore, it is a reflective artificial electromagnetic surface.

[0049] The working principle of this MOS switch-controlled gain millimeter-wave programmable metasurface is as follows. When an x-polarized incident wave is perpendicular to the metasurface, the electromagnetic wave energy is coupled to the microstrip transmission line through an hourglass-shaped slot in the center of the metal backplate. After amplification by a power amplifier, the channel is selected by changing the on / off state of the MOS switch chips bonded to two different microstrip transmission lines. One hourglass-shaped radiating slot orthogonal to the central slot is selected to implement y-polarized secondary radiation. The radiating slots of the two channels are designed with anti-phase feeding to achieve reflected waves with similar amplitudes and a 180° phase difference. By selecting a suitable operating frequency band, the reflected amplitudes of the units are similar and the phases differ by 180° in both states of the electromagnetic wave, thus obtaining two basic encoding units, labeled "0" and "1" respectively. By arranging different encoding units into a specific sequence, a metasurface with a certain function can be obtained. Since the unit structure is the same, this greatly simplifies the arraying process. Here, the present invention will integrate FPGA with metasurface array. For complex arrays with specific functional requirements, the coded sequence obtained by calculation simulation can be stored in FPGA, and the FPGA can realize the rapid switching of the metasurface coded state to obtain the required far-field beam distribution.

[0050] Example 1: As Figure 3The structural unit shown has a square unit with a period of p = 5000 μm and a rectangular radiating patch width of p1 = 2650 μm. The microstrip line lengths are l1 = 3450 μm, l2 = 1200 μm, l3 = 1800 μm, and l4 = 900 μm, with a microstrip width of w = 200 μm. Interfaces of 1400 μm and 920 μm are reserved between the four microstrip sections for MOS switch and amplifier chips, respectively. The chips are bonded to the microstrips using gold wire bonding. The dimensions of the horizontal and vertical hourglass grooves are a1 = 300 μm, a2 = 425 μm, b1 = 100 μm, b2 = 1000 μm and a3 = 300 μm, a4 = 425 μm, b3 = 100 μm, b4 = 740 μm, respectively. The substrates are RO4350B and Rogers RO4450F. The 5-layer dielectric structure consists of overlapping PP layers. The central layer has a thickness of h2 = 200µm, and the remaining layers have a thickness of h1 = 100µm. Metal layers, made of copper and 35µm thick, serve as control and power traces between the layers. The outermost microstrip and rectangular patch layers have a copper thickness of 18µm. By switching the MOS switch chip on and off, the "0" and "1" states under different polarizations are obtained.

[0051] Electromagnetic simulation of the above unit was performed using the CST Microwave Studio, and the S-parameters without an amplifier were obtained as follows: Figure 4 and Figure 5 As shown. Around 30 GHz, the amplitude of the reflection coefficient S12 is approximately equal in both states, while the phase differs by 180°, conforming to the requirements of the "0" and "1" states in the aforementioned coded metasurface. Using CST for field-circuit co-simulation, the S-parameters are as follows when the amplifier circuit is loaded: Figure 6 and Figure 7 As shown, near 30 GHz, the amplitude of the reflection coefficient S12 is basically equal in both states, with a gain of more than 4 dB, while the phases differ by 180°, which meets the design goal of the gain-coded metasurface.

[0052] In a passive state, for the same metasurface array, when x-polarized electromagnetic waves are incident perpendicularly, an array structure with the encoding sequence 0110011001 was designed, where each column of cells is combined into a subarray for array arrangement. At an operating frequency of 30 GHz, the three-dimensional far-field scattering pattern of the metasurface is as follows. Figure 8 As shown. By Figure 8 It can be seen that the positive reflection beam is significantly suppressed and becomes two scattering beams at an angle of 30° with the z-axis. When a power amplifier is applied, the metasurface unit has the same 1-bit effect and active amplification characteristics, which can perform controllable angle active amplification and reflection of the reflected signal.

[0053] Example 2: Figure 3The structural unit shown has a square unit with a period of p = 5000 μm and a rectangular radiating patch width of p1 = 2650 μm. The microstrip line lengths are l1 = 3450 μm, l2 = 1200 μm, l3 = 1800 μm, and l4 = 900 μm, with a microstrip width of w = 200 μm. Interfaces of 1400 μm and 920 μm are reserved between the four microstrip sections for MOS switch and amplifier chips, respectively. The chips are bonded to the microstrips using gold wire bonding. The dimensions of the horizontal and vertical hourglass grooves are a1 = 300 μm, a2 = 425 μm, b1 = 100 μm, b2 = 1000 μm and a3 = 300 μm, a4 = 425 μm, b3 = 100 μm, b4 = 740 μm, respectively. The substrates are RO4350B and Rogers RO4450F. The 5-layer dielectric structure consists of overlapping PP layers. The central layer has a thickness of h2 = 200µm, and the remaining layers have a thickness of h1 = 100µm. Metal layers, made of copper and 35µm thick, serve as control and power traces between the layers. The outermost microstrip and rectangular patch layers have a copper thickness of 18µm. By switching the MOS switch chip on and off, the "0" and "1" states under different polarizations are obtained.

[0054] In a passive state, for the same metasurface array, when x-polarized electromagnetic waves are incident perpendicularly, an array structure with the encoding sequence 0111000111 is designed, where each column of cells is combined into a subarray for array arrangement. At an operating frequency of 30 GHz, the three-dimensional far-field scattering pattern of the metasurface is as follows. Figure 9 As shown. By Figure 9 It can be seen that the positive reflection beam is significantly suppressed and becomes two scattering beams at an angle of 20° with the z-axis. When a power amplifier is applied, the metasurface unit has the same 1-bit effect and active amplification characteristics, which can perform controllable angle active amplification and reflection of the reflected signal.

[0055] According to an embodiment of the present invention, a MOS switch-controlled gain millimeter-wave programmable metasurface is proposed. This structure realizes a reflective metasurface unit integrating a power amplifier and a MOS switch chip. It achieves x-polarized wave reception within a high-isolation dual-polarized rectangular patch antenna unit structure, and after microstrip transmission amplification, it is re-radiated as a y-polarized wave. By adjusting the on / off state of the MOS switch chip, the y-polarized reflection phase can be changed, enabling good 1-bit performance while ensuring active signal amplification. This allows for coded state switching of the metasurface unit and far-field beam control of the metasurface array. This is a millimeter-wave artificial electromagnetic surface with active amplification capabilities, which is expected to solve the path loss and reflection loss problems of current reflective metasurfaces, as well as the RF signal leakage problem caused by the programmable metasurface bias circuit. It has important potential applications in fields such as intelligent communication, imaging, and computing technologies.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A gain-controlled millimeter-wave programmable metasurface with MOS switch, characterized in that, The metasurface is composed of a two-dimensional array of multiple subwavelength units. Each subwavelength unit includes a radiating patch (1), a microstrip radio frequency link (2), a substrate (3), a power amplifier chip (7), a MOS switch chip (8), and a slotted metal backplate (4). The radiation patch (1) is disposed on the top layer of the subwavelength unit and etched on the substrate; The microstrip radio frequency link (2) is located on the bottom layer of the subwavelength unit, on the back side of the substrate. The substrate (3) is a multilayer dielectric structure with a metal structure layer (6) between each dielectric layer. The slotted metal backplate (4) is etched on the metal structure layer between the bottom layer and the sub-bottom layer dielectric, and is separated from the microstrip RF link by a dielectric layer; the metal backplate is provided with three hourglass-shaped radiation slots (5), of which the vertically open radiation slot is located at the center of the backplate and is orthogonally arranged with the other two horizontally open hourglass-shaped radiation slots; the slotted metal backplate uses hourglass-shaped slots to ensure that electromagnetic energy is efficiently coupled to the bottom microstrip transmission link, and after being amplified by the power amplifier, the channel is selected by the MOS switch. The two channels are respectively connected to the two hourglass-shaped radiation slots orthogonal to the vertically open radiation slots. The two radiation slots are fed in opposite phases to achieve a 180° phase difference while implementing secondary radiation; The power amplifier chip (7) and two MOS switch chips (8) are attached to the back of the substrate and bonded to the microstrip RF link by gold wire.

2. The gain-modulated millimeter-wave metasurface with MOS switch control according to claim 1, characterized in that, The radiating patch has a rectangular structure, is made of copper, and operates at the millimeter-wave frequency band.

3. The gain-modulated millimeter-wave metasurface with MOS switch control according to claim 1, characterized in that, The substrate is a 5-layer dielectric structure consisting of overlapping Rogers RO4350B and Rogers RO4450F, with Rogers RO4450F as the top layer. The dielectric constants are 3.66 and 3.7, and the loss tangents are 0.0037 and 0.004, respectively.

4. The gain-modulated millimeter-wave programmable metasurface with MOS switch control according to claim 1, characterized in that, The underlying microstrip RF link and the slotted metal backplane are made of copper.

5. The gain-modulated millimeter-wave programmable metasurface with MOS switch control according to claim 1, characterized in that, Different coding arrangements are calculated based on different functional requirements. Field programmable gate arrays are used to programmatically control the distribution of bias voltage and reconstruct the reflection phase distribution.

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