Super surface with arbitrary control of polarization and phase at linear and nonlinear frequencies

Abstract

The application discloses a kind of super surface of linear and nonlinear frequency place polarization and phase arbitrary control, including upper sub-super surface unit and lower sub-super surface unit, upper sub-super surface unit is passive structure with anisotropic characteristics, lower sub-super surface unit is independently and continuously adjustable in x and y two directions, by controlling the voltage in two directions, linear and nonlinear frequency place polarization and phase can be realized arbitrary control, processing cost is low, installation is convenient, and easy to integrate, with good versatility, by adjusting the size of unit, it can be designed in different working frequency bands, easy to popularize and apply.It has potential application value in electronic countermeasure, wireless communication and imaging.

Description

Technical Field

[0001] This invention relates to the field of novel artificial electromagnetic materials technology, and in particular to a metasurface with arbitrary control over polarization and phase at linear and nonlinear frequencies. Background Technology

[0002] In information-based environments, studying the polarization and phase of electromagnetic waves is crucial for their propagation in space. In communication technology, electromagnetic waves exhibit different propagation characteristics depending on their polarization. By combining the polarization characteristics of transmitting and receiving antennas, optimal transmission and reception of electromagnetic waves can be achieved. Furthermore, in communication systems, phase can be used to modulate transmitted signals, for example, using modulation techniques such as BPSK and QPSK. In countermeasures research, antennas utilizing vertically polarized waves can effectively suppress interference from enemy horizontally polarized waves. Simultaneously, continuous phase control is necessary for continuous beam scanning. To adapt to the characteristics of modern electronic warfare, such as its deep penetration, omnidirectional range, high mobility, and dense and constantly changing battlefield information, the demand for adaptive antenna polarization and phase is increasingly urgent. Therefore, antennas with arbitrarily controllable polarization and phase have significant new applications in modern radar, communications, and electronic reconnaissance and jamming. However, achieving arbitrary polarization and phase typically requires designing complex feeding systems or using bulky rotating array antennas. Therefore, metasurfaces with arbitrarily controllable polarization and phase have potential applications in communications and electric field anti-jamming. Summary of the Invention

[0003] This invention provides a metasurface with arbitrary controllable polarization and phase at linear and nonlinear frequencies. It features simultaneous control of multiple electromagnetic wave properties by electromagnetic waves, low cost, and easy integration, and has high engineering application value.

[0004] This invention provides a metasurface with arbitrary polarization and phase control at linear and nonlinear frequencies, comprising: an upper-level sub-metasurface unit and a lower-level sub-metasurface unit, wherein the upper-level sub-metasurface unit is a passive structure with anisotropic characteristics, and the lower-level sub-metasurface unit has independent and continuously adjustable phase in both the x and y directions.

[0005] In one embodiment of the present invention, the overall reflection matrix characteristics of the metasurface satisfy a preset relationship between the polarization and phase of the reflected wave and the phase in the x and y directions of the bottom structure.

[0006] In one embodiment of the present invention, the metasurface is controlled by an external FPGA control circuit. When the external control voltage is a time-invariant signal, the polarization direction of the reflected wave at a linear frequency is controlled by controlling the voltage difference in the x and y directions of the lower-level sub-metasurface unit, and the phase of the reflected wave at a linear frequency is controlled by controlling the voltage sum in the x and y directions. When the external control voltage is a time-varying periodic signal, the polarization direction of the reflected wave at a nonlinear frequency is controlled by controlling the voltage difference in the x and y directions of the lower-level sub-metasurface unit, and the phase of the reflected wave at a nonlinear frequency is controlled by controlling the initial voltage sum in the x and y directions.

[0007] In one embodiment of the present invention, the overall reflection matrix of the metasurface satisfies the following preset relationship: in, Excitation by x-polarized wave x Polarized wave reflection, for y Polarization wave excitation x Polarized wave reflection, for x Polarization wave excitation y Polarized wave reflection, for y Polarization wave excitation y Polarized wave reflection, for and Half of the reflection phase, for and Half of the reflected phase difference, For the lower sub-metasurface unit in y Co-polarized reflection phase under polarized wave excitation For the lower sub-metasurface unit in x Common polarization reflection phase under polarization wave excitation.

[0008] In one embodiment of the present invention, the upper-level sub-metasurface unit is composed of three layers of metal patches and two layers of dielectric substrate; The lower-level metasurface unit consists of three metal patches, two dielectric substrates, metallized vias, four varactor diodes, and four inductors.

[0009] In one embodiment of the present invention, the four varactor diodes of the lower-level sub-metasurface unit are symmetrically welded in the x and y directions. By continuously changing the bias voltage of the varactor diodes, a continuous reflection phase is obtained. The varactor diodes in the x and y directions are independently fed by the bias circuit, thereby achieving an independently and continuously adjustable reflection phase in both the x and y directions. and .

[0010] In one embodiment of the present invention, the dielectric substrate is made of F4B and the metal patch is made of copper.

[0011] The metasurface with arbitrary polarization and phase control at linear and nonlinear frequencies according to embodiments of the present invention has the following beneficial effects: 1. The principle of this invention is simple; it can achieve arbitrary control of polarization and phase at linear and nonlinear frequencies simply by controlling the voltage in two directions. 2. This invention arranges multiple basic units into an array, controlled by the same signal, which reduces the interference caused by different boundaries on the reflection coefficient of the units, and also reduces the design complexity of the power supply network. 3. Compared with traditional metasurfaces, this invention can simultaneously achieve polarization and phase control; 4. The present invention has high structural conversion efficiency.

[0012] 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

[0013] 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: Figure 1 A diagram of a metasurface structure with arbitrary polarization and phase control at linear and nonlinear frequencies provided by an embodiment of the present invention; Figure 2 This is a schematic diagram of the peripheral control circuit and functions of a 10×10 array according to an embodiment of the present invention. Figure 3 (a) is a perspective view of the upper AR structure unit, (b) is a perspective view of the lower sub-metasurface unit (RPM) structure, and (c) is a 6×6 array and the electromagnetic wave transmission process. Figure 4 To illustrate the amplitude and phase characteristics of the unit under different phase combinations and the synthesized polarization direction under y-polarized wave excitation according to embodiments of the present invention: (a) 0° / 0°, (b) 0° / 90°, (b) 0° / 180°, (b) 90° / 0°; the figures represent simulation results and measured results. Figure 5According to an embodiment of the present invention, for y-polarized wave excitation under phase combinations of 180° / 0°, 270° / 90°, 0° / 180°, and 90° / 270°, (a) simulated and measured common polarization reflection amplitude, (b) simulated and measured common polarization reflection phase. Under phase combinations of 0° / 0°, 90° / 90°, 180° / 180°, and 270° / 270°, (c) simulated and measured cross-polarization reflection amplitude, (d) simulated and measured cross-polarization reflection phase; the figures show the simulation results, and the dashed lines represent the measured results. Figure 6 To illustrate the different polarizations of reflected waves according to embodiments of the present invention, and The 2-bit time-coded sequence (top column). and The graphs showing the changes over time (middle column) along with the corresponding theoretical and test results are as follows: (a) 0° polarization reflected wave, (b) 45° polarization reflected wave, and (c) 90° polarization reflected wave. Figure 7 (a) is the spatiotemporal coding matrix of 0° polarization reflected wave, (b) is the spatiotemporal coding matrix of 45° polarization reflected wave, (c) is the spatiotemporal coding matrix of 90° polarization reflected wave, (d) is the normalized two-dimensional dispersion pattern measured under the spatiotemporal coding matrix mode of 0° polarization reflected wave, (e) is the normalized two-dimensional dispersion pattern measured under the spatiotemporal coding matrix mode of 45° polarization reflected wave, and (f) is the normalized two-dimensional dispersion pattern measured under the spatiotemporal coding matrix mode of 90° polarization reflected wave. Detailed Implementation

[0014] 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.

[0015] Figure 1 This is a diagram of a metasurface structure with arbitrary polarization and phase control at linear and nonlinear frequencies, provided according to an embodiment of the present invention.

[0016] like Figure 1 As shown, the metasurface with arbitrary polarization and phase control at linear and nonlinear frequencies includes: The upper-level sub-metasurface unit and the lower-level sub-metasurface unit are defined as follows: the upper-level sub-metasurface unit is a passive structure with anisotropic characteristics, and the lower-level sub-metasurface unit has independent and continuously adjustable phases in both the x and y directions.

[0017] Specifically, the metasurface units are constructed in a cascaded manner. The upper-level sub-metasurface unit (AR) consists of two dielectric substrates of the same thickness and three metal patches. The lower-level sub-metasurface unit (RPM) consists of two dielectric substrates, three metal patches, metallized vias, four varactor diodes, and four inductors.

[0018] In one embodiment, the dielectric substrate is made of F4B and the metal patch is made of copper.

[0019] Furthermore, the overall reflection matrix characteristics of the metasurface satisfy a preset relationship between the polarization and phase of the reflected wave and the phase in the x and y directions of the bottom structure; that is, the polarization and phase of the reflected wave are related to the phase in the x and y directions of the bottom structure. The metasurface is controlled by an external FPGA control circuit. When the external control voltage is a time-varying signal, the polarization direction of the reflected wave at the linear frequency is controlled by controlling the voltage difference in the x and y directions of the lower-level sub-metasurface units, and the voltage and phase of the reflected wave at the linear frequency are also controlled. When the external control voltage is a time-varying periodic signal, the polarization direction of the reflected wave at the nonlinear frequency is controlled by controlling the voltage difference in the x and y directions of the lower-level sub-metasurface units, and the initial voltage and phase of the reflected wave at the nonlinear frequency are also controlled.

[0020] The predefined relationship satisfied by the overall reflection matrix of the metasurface is: in, Excitation by x-polarized wave x Polarized wave reflection, for y Polarization wave excitation x Polarized wave reflection, for x Polarization wave excitation y Polarized wave reflection, for y Polarization wave excitation y Polarized wave reflection, for and Half of the reflection phase, for and Half of the reflected phase difference, For the lower sub-metasurface unit in y Co-polarized reflection phase under polarized wave excitation For the lower sub-metasurface unit in x Common polarization reflection phase under polarization wave excitation.

[0021] By combining this metasurface with spatiotemporal coding theory, simultaneous control of polarization, beamforming, and spectrum can be achieved. The operating frequency of this invention is 3.5 GHz. The simulated conversion efficiency of the designed structure is -1.2 dB. This invention features multifunctionality, low processing cost, convenient installation, ease of integration, and good versatility. By adjusting the integer dimensions of the metasurface units, it can be designed for different operating frequency bands, facilitating widespread application. It has potential applications in electronic warfare, wireless communication, and imaging.

[0022] like Figure 2 As shown, Figure 2 This is a schematic diagram of a 10×10 array and its electromagnetic wave reflection function. The polarization, beam, and spectrum of the reflected wave can be controlled in real time by an external FPGA control circuit. A perspective view of the upper-layer AR structure unit is shown below. Figure 3 As shown in Figure a, each basic unit consists of an upper metal patch, a middle metal patch, a bottom metal patch, an upper dielectric layer, and a lower dielectric layer. Its unit's transmission matrix is... The perspective view of the bottom RPM structural unit is as follows. Figure 3 As shown in b, each basic unit consists of an upper metal patch, a middle metal ground patch, a bottom metal feed line, an upper dielectric layer, a lower dielectric layer, metallized vias, four varactor diodes on the upper surface, and four inductors at the bottom. The unit substrate is F4B microwave composite material with a dielectric constant of 2.4. Each unit measures 20 × 20 × 6 mm. The reflection matrix of the bottom unit is... .in It means and Half of the sum, and It means and Half the difference. Reflection phase. and The capacitance changes as the varactor diode's capacitance value changes. The varactor diode selected here is a Skyworks-SMV1405; its capacitance value can change with variations in the external voltage. and It is continuously adjustable because the bottom structure of this invention has independent power supply in the x and y directions, so it does not interfere with each other. and It is independently adjustable, and the bottom structure is symmetrical, so the reflected phase value is the same under the same voltage. and The adjustable range is approximately 308°. Each unit measures 20×20×4.5 mm. For example... Figure 3c represents a 6×6 array and the electromagnetic wave propagation process. The combined unit reflection matrix is: As can be seen from the formula, the polarization and phase of the reflected wave are respectively related to... and Therefore, polarization and phase can be controlled by voltages in the x and y directions.

[0023] Figure 4 The figure shows simulation and measured results for different phase combinations under y-polarized wave excitation. The phases before and after the slash ( / ) in the figure represent... and Derivation based on the formula Figure 4 The theoretical polarization directions of the a and b axes are 0°, 45°, 90°, and -45°. As can be seen from the figure, the theoretical, simulation, and experimental results are very close. This invention only demonstrates a few special combinations; because the phase is continuously controllable, the polarization can be deflected to any orientation.

[0024] Figure 5 The present invention provides simulated and measured cross-polarized reflection amplitudes and phases under y-polarized wave excitation, with (ab) phase combinations of 180° / 0°, 270° / 90°, 0° / 180°, and 90° / 270°. (cd) Simulated and measured common-polarized reflected wave amplitudes and phases are also presented under 0° / 0°, 90° / 90°, 180° / 180°, and 270° / 270° phase combinations. The figures show that the simulated reflection amplitudes are all above -1.2 dB, and each polarization state can achieve a 2-bit phase state. The simulation and measured results agree well. For 2-bit phase modulation of other polarized reflected waves, we can achieve this through other encoding methods.

[0025] The above discussion focuses on the simulation and experimental results of polarization and phase at linear frequencies. Polarization and phase at nonlinear frequencies are arbitrarily controllable. Time-varying periodic phase signals are introduced in the x and y directions, and these signals are synchronized; therefore, the phase difference between the two directions is... It is a constant, while Changes over time. Figure 6 The top column of the AC value shows the reflected waves under 0° polarization, 45° polarization, and 90° polarization respectively. and A 2-bit time-coded sequence diagram. Figure 6 The middle column of ac shows the corresponding Δφ and β as a function of time. Figure 6The bottom bar of the AC diagram shows the theoretically calculated and tested spectral distributions. It can be seen from the diagram that the energy of the theoretical and tested spectra is mainly concentrated at the +1 order. Theoretically, the reflected energy at the 0th order (fundamental wave) is 0, while in the actual measurement, there is a certain energy distribution. This is mainly due to energy reflection in space and the incomplete interaction of electromagnetic waves. Other spectral distributions are very similar to the measured results. For some spectral intensities that are zero in theory but have certain intensity in the actual measurement, this is mainly because the phase difference between adjacent encoded elements is not exactly 90° in practice. Combining the above factors, it shows that this structure can achieve controllable polarization at nonlinear frequencies. The controllable phase at nonlinear frequencies refers to the phase at the initial moment. This can be obtained by controlling the voltage applied to the metasurface at the initial moment using an FPGA. To demonstrate the ability to control polarization and phase at nonlinear frequencies, we introduce 2-bit phase encoding in both time and space, combining spatiotemporal coding theory. Figure 7 The ac values ​​provide the spatiotemporal coding matrices for 0°, 45°, and 90° polarization, respectively. Based on spatiotemporal coding theory, the deflection angles calculated at -3 and +1 orders are approximately 32.4°. Figure 7 The paper presents test results for the normalized two-dimensional radiation patterns at -3rd, +1st, and 0th orders of polarization, and the deflection angles are consistent with theoretical calculations. The consistency between theory, simulation, and experimental results demonstrates that this structure can achieve independent controllability of polarization and phase at both linear and nonlinear frequencies. Other beam and polarization deflection angles can be obtained by changing the coding method; therefore, this invention, combined with spatiotemporal coding theory, can achieve independent control of the spectrum, beam, and polarization. This invention features high efficiency and real-time controllability in polarization and phase modulation, making it highly valuable for applications in communications, electronic countermeasures, and microwave imaging.

[0026] The metasurface proposed in this invention, which allows for arbitrary control of polarization and phase at linear and nonlinear frequencies, can achieve arbitrary control of polarization and phase at linear and nonlinear frequencies simply by controlling the voltage in two directions. It features low manufacturing cost, convenient installation, easy integration, and good versatility. By adjusting the size of the unit, it can be designed for different operating frequency bands, facilitating widespread application. It has potential application value in electronic warfare, wireless communication, and imaging.

[0027] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is 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.

[0028] 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 metasurface with arbitrarily modulated polarization and phase at linear and nonlinear frequencies, characterized in that, include: The upper-level sub-metasurface unit and the lower-level sub-metasurface unit are constructed in a cascaded manner. The upper-level sub-metasurface unit is a passive structure with anisotropic characteristics, and the lower-level sub-metasurface unit has independent and continuously adjustable phase in both the x and y directions. The overall reflection matrix characteristics of the metasurface satisfy a preset relationship between the polarization and phase of the reflected wave and the phase in the x and y directions of the bottom structure; the preset relationship satisfied by the overall reflection matrix of the metasurface is: ； in, Excitation by x-polarized wave x Polarized wave reflection, for y Polarization wave excitation x Polarized wave reflection, for x Polarization wave excitation y Polarized wave reflection, for y Polarization wave excitation y Polarized wave reflection, for and Half of the reflection phase, for and Half of the reflected phase difference, For the lower sub-metasurface unit in y Co-polarized reflection phase under polarized wave excitation For the lower sub-metasurface unit in x Common polarization reflection phase under polarization wave excitation.

2. The metasurface according to claim 1, characterized in that, The metasurface is controlled by an external FPGA control circuit. When the external control voltage is a time-invariant signal, the polarization direction of the reflected wave at the linear frequency is controlled by controlling the voltage difference in the x and y directions of the lower-level sub-metasurface unit, and the phase of the reflected wave at the linear frequency is controlled by controlling the voltage sum in the x and y directions. When the external control voltage is a time-varying periodic signal, the polarization direction of the reflected wave at the nonlinear frequency is controlled by controlling the voltage difference in the x and y directions of the lower-level sub-metasurface unit, and the phase of the reflected wave at the nonlinear frequency is controlled by controlling the initial voltage sum in the x and y directions.

3. The metasurface according to claim 1, characterized in that, The upper-level sub-metasurface unit consists of three layers of metal patches and two layers of dielectric substrate; The lower-level metasurface unit consists of three metal patches, two dielectric substrates, metallized vias, four varactor diodes, and four inductors.

4. The metasurface according to claim 3, characterized in that, The four varactor diodes of the lower-level sub-metasurface unit are symmetrically welded in the x and y directions. By continuously changing the bias voltage of the varactor diodes, a continuous reflection phase is obtained. By independently feeding the varactor diodes in both the x and y directions using a bias circuit, an independent and continuously adjustable reflection phase can be achieved in both the x and y directions. and .

5. The metasurface according to claim 3, characterized in that, The dielectric substrate is made of F4B, and the metal patch is made of copper.

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