Low power consumption co-gain adjustable metasurface based on nonlinear negative resistance

Abstract

The application discloses a low-power-consumption common-gain adjustable metasurface based on nonlinear negative resistance, which comprises a low-power-consumption metasurface unit and a backscattering amplifier connected in series with the low-power-consumption metasurface unit; the low-power-consumption metasurface unit comprises, from top to bottom, an upper copper sheet, an upper dielectric, a metal ground, a lower dielectric and a bottom RLC switching circuit layer; wherein the upper copper sheet is connected with the bottom RLC switching circuit through a through hole; the bottom RLC switching circuit layer comprises a plurality of radio frequency switches and LC circuits or resistors embedded between the radio frequency switches; the backscattering amplifier comprises a matching circuit, the matching circuit is connected with an amplifying circuit through a direct-current isolation part, and the amplifying circuit is connected with a bias circuit through a cross isolation part. After an electromagnetic signal is input into the amplifying circuit through the bottom RLC switching circuit, the LC circuit or the resistor is selected through the radio frequency switch, the electromagnetic signal is amplified, and then the electromagnetic signal is reflected, the LC circuit or the resistor is selected through the radio frequency switch, the electromagnetic signal is transmitted to the upper copper sheet, and then the electromagnetic signal is radiated to the free space.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency antennas, and particularly relates to a low-power, high-gain tunable metasurface based on nonlinear negative resistance. Background Technology

[0002] Intelligent metasurface (RIS) technology employs novel programmable subwavelength two-dimensional metamaterials to actively and intelligently control electromagnetic waves through digital coding, forming electromagnetic fields with controllable amplitude, phase, polarization, and frequency characteristics. By actively controlling the wireless propagation environment, RIS technology enables signal propagation direction modulation, signal enhancement, or interference suppression in free space, constructing a new paradigm for intelligent programmable wireless environments. It can be applied to scenarios such as electromagnetic signal coverage enhancement, overcoming local voids, improving cell edge user speeds, green communication, assisting in electromagnetic environment sensing, and high-precision positioning.

[0003] Traditional smart metasurface research and design largely involves equipping devices with switching phase-controlled components, such as PIN diodes, varactor diodes, liquid crystals, or phase-change materials. External control circuits are primarily used for controlling the state of these components. Essentially, traditional smart metasurfaces, as a technology for electromagnetic environment regulation, cannot achieve gain on electromagnetic waves. However, while theoretically traditional smart metasurface technology can provide array gain proportional to the square of the number of surface elements, it also introduces a "multiplicative fading" effect. This means the path loss of the metasurface reflection link (base station-RIS-user) is the product of the path losses of the transmitter-RIS and RIS-user sub-links. This multiplicative fading effect severely diminishes the array gain, significantly limiting the performance gain of the RIS in typical scenarios where a good communication link already exists between the base station and the user (either a direct or indirect path).

[0004] To address the gain limitation caused by the multiplicative fading effect in traditional smart metasurface technology, the concept of gain-type RIS (Radio-Resonant Array) was proposed. In gain-type RIS, the array elements amplify electromagnetic signals, enabling phase tuning and power amplification of the incident signal. This amplification of the incident wave enhances the power of the RIS's scattered echo, making the signal loss under the multiplicative fading effect comparable to that under a direct path, and even enabling longer-distance link transmission. However, most current active RIS designs employ field-effect transistors (FETs) and power amplifiers, which suffer from excessive power consumption and are prone to self-oscillation, posing a significant disadvantage for large-scale deployment in the future.

[0005] Meanwhile, the tuning and modulation capabilities of reflective amplifiers based on pHEMT, FET and bipolar transistor devices are being explored. These devices can also provide low cost and flexible design freedom, but it is difficult to achieve low power consumption. Summary of the Invention

[0006] In view of this, the present invention provides a low-power common-gain tunable metasurface based on nonlinear negative resistance.

[0007] To achieve the above-mentioned objectives, the technical solution of this invention is a low-power common-gain tunable metasurface based on nonlinear negative resistance, comprising: a low-power metasurface unit and a backscattering amplifier connected in series therewith.

[0008] The low-power metasurface unit includes, from top to bottom, an upper copper sheet, an upper dielectric, a metal ground, a lower dielectric, and a bottom RLC switching circuit layer; wherein, the upper metal sheet is connected to the bottom RLC switching circuit through vias; the bottom RLC switching circuit layer includes several radio frequency switches, and LC circuits or resistors embedded between the radio frequency switches;

[0009] The backscattering amplifier includes: a matching circuit, a DC blocking circuit, and an amplification circuit. The DC blocking circuit is disposed between the matching circuit and the low-power metasurface unit or between the matching circuit and the amplification circuit. The amplification circuit is connected to the bias circuit via an AC blocking circuit.

[0010] The low-power metasurface unit receives electromagnetic signals, which are transmitted to the bottom RLC switching circuit through the upper copper sheet and vias. After the LC circuit or resistor is selected by the RF switch, the electromagnetic signal is amplified by the matching circuit and then reflected. After the LC circuit or resistor is selected by the RF switch, the signal is transmitted to the upper copper sheet through vias and then radiated into free space.

[0011] Furthermore, the shape of the upper copper sheet is selected from square, rectangle, polygon, and circle.

[0012] Furthermore, the upper copper sheet is equivalent to an upper inductor L connected in series. top Upper capacitor C top Upper layer resistor R top A through-hole is equivalent to an inductor L. via The underlying RLC switching circuit layer also includes a matching structure, which is equivalent to an inductor L. metal .

[0013] Furthermore, the DC blocking circuit uses a DC blocking capacitor, and the AC blocking circuit uses an AC blocking inductor.

[0014] Furthermore, the underlying RLC switching circuit layer includes a plurality of radio frequency switches, and the LC circuit or resistor embedded between the radio frequency switches includes:

[0015] The underlying RLC embedded circuit layer includes a single-pole four-throw switch SP4T, a first LC circuit embedded between the first RF switch RF1, a second LC circuit embedded between the second RF switch RF2, a third LC circuit embedded between the third RF switch RF3, and a fourth LC circuit embedded between the fourth RF switch RF4. By switching the RF switches to select different LC circuits, the phase modulation of electromagnetic waves can be achieved.

[0016] or,

[0017] The underlying RLC embedded circuit layer includes several radio frequency switches, a first resistor embedded between the first radio frequency switch RF1, a second resistor embedded between the second radio frequency switch RF2, a third resistor embedded between the third radio frequency switch RF3, a fourth resistor embedded between the fourth radio frequency switch RF4, ..., an Nth resistor embedded between the Nth radio frequency switch RFN. By switching the radio frequency switches, different resistors are selected to achieve the absorption of electromagnetic waves.

[0018] or,

[0019] The underlying RLC switching circuit layer includes several radio frequency switches, as well as LC circuits or resistors embedded between the radio frequency switches and combinations thereof. Specifically, the underlying RLC switching circuit layer includes several radio frequency switches, a first LC circuit embedded between the first radio frequency switch RF1, a second LC circuit embedded between the second radio frequency switch RF2, a third LC circuit embedded between the third radio frequency switch RF3, a fourth LC circuit embedded between the fourth radio frequency switch RF4, a first resistor embedded between the fifth radio frequency switch RF5, a second resistor embedded between the sixth radio frequency switch RF6, ..., an Nth resistor embedded between the Nth radio frequency switch RFN. By switching the radio frequency switches, different LC circuits or resistors are selected to achieve phase modulation or absorption of electromagnetic waves.

[0020] Furthermore, the matching circuit adopts an LC circuit, which uses a series capacitor and inductor to form a frequency selection circuit for the backscattering amplifier to determine the operating frequency of the circuit.

[0021] Furthermore, the amplifier circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor Q1, and a second transistor Q2. One end of the first resistor R1 is connected to one end of the fourth resistor R4 and the collector of the first transistor Q1; the other end of the first resistor R1 is connected to the base of the first transistor Q1 and the collector of the second transistor Q2; the emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2 and one end of the second resistor R2; the base of the second transistor Q2 is connected to the other end of the fourth resistor R4 and one end of the third resistor R3; the other end of the second resistor R2 is connected to the other end of the third resistor R3 and grounded.

[0022] Furthermore, the first transistor Q1 and the second transistor Q2 are selected as NPN transistors or PNP transistors. The bias voltage of the first transistor Q1 is increased, while the bias voltage of the second transistor Q2 is decreased, so that the circuit has a nonlinear negative resistance region under a bias voltage of less than 1V.

[0023] Furthermore, when the RF switch selects an LC circuit, the expression for the impedance Z(C,L,f) of the low-power common-gain tunable metasurface based on nonlinear negative resistance is as follows:

[0024]

[0025] In the formula, j represents the imaginary number, f represents the frequency, L represents the inductance between the embedded RF switches, and C represents the capacitance between the embedded RF switches;

[0026] The expression for the reflection coefficient Γ(C,L,f) of electromagnetic waves is as follows:

[0027]

[0028] In the formula, Z0 represents the free space impedance.

[0029] Furthermore, when the RF switch selects a resistor, the expression for the impedance Z(R,f) of the low-power common-gain tunable metasurface based on nonlinear negative resistance is as follows:

[0030]

[0031] In the formula, j represents an imaginary number, f represents the frequency, and R represents the resistance between the embedded RF switches;

[0032] The expression for the electromagnetic wave absorption rate A of the low-power common-gain tunable metasurface based on nonlinear negative resistance is as follows:

[0033] A = 1 - |Γ(R,f)| 2

[0034] In the formula, Γ(R,f) represents the reflection coefficient of the electromagnetic wave, and its expression is as follows:

[0035]

[0036] In the formula, Z0 represents the free space impedance.

[0037] Compared with existing technologies, the advantages of this invention are as follows: Compared with the difficulty in balancing structural and design complexity in PIN diode-based metasurface designs, and the problems of excessive power consumption and overly complex bias circuits in varactor diode-based metasurface designs, the low-power intelligent reflective surface unit design implemented in this invention using low-power components such as RF switches, capacitors, and inductors not only achieves functionality comparable to traditional metasurfaces in terms of design complexity, but also significantly reduces overall power consumption. Furthermore, the low-power, high-gain backscattering amplifier proposed in this invention, through its backscattering amplification function of RF signals, can avoid self-oscillation to a certain extent. Simultaneously, the amplification characteristics of this backscattering amplifier can be tuned by adjusting the bias or resistance value, and the power consumption of the entire amplification circuit is in the microwatt range. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a model diagram of the low-power metasurface unit structure provided in the embodiments of the present invention;

[0040] Figure 2 This is a block diagram of the design structure for achieving multi-functional control using a low-power metasurface unit structure provided in an embodiment of the present invention;

[0041] Figure 3 This is a structural block diagram of the nonlinear negative resistance backscattering amplifier provided in the embodiment of the present invention;

[0042] Figure 4 This is the IV curve of the nonlinear negative resistance backscattering amplifier provided in the embodiment of the present invention;

[0043] Figure 5 This is a structural block diagram of the first embodiment of the low-power, high-gain, reflective tunable metasurface based on nonlinear negative resistance provided by the present invention.

[0044] Figure 6 This is a structural block diagram of the second embodiment of the low-power, high-gain, reflective tunable metasurface based on nonlinear negative resistance provided by the present invention;

[0045] Figure 7 This is a structural block diagram of the third embodiment of the low-power, high-gain, reflective tunable metasurface based on nonlinear negative resistance provided by the present invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] It should be noted that, unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other.

[0048] To address the "multiplicative fading" effect in traditional smart metasurface links, this invention provides a low-power, common-gain tunable metasurface based on nonlinear negative resistance, comprising a low-power metasurface unit and a backscattering amplifier connected in series therewith.

[0049] like Figure 1 As shown in (a), the low-power metasurface unit includes, from top to bottom, an upper copper layer, an upper dielectric layer, a metal ground layer, a lower dielectric layer, and a bottom RLC switching circuit layer; wherein, as Figure 2 As shown in (b), the upper metal sheet is connected to the lower RLC switching circuit through a through hole, thereby realizing the processes of receiving, modulating and radiating incoming waves.

[0050] Furthermore, such as Figure 1 As shown in (b), the shape of the upper copper sheet includes, but is not limited to, rectangles, squares, polygons, and circles; in this example, the upper metal sheet uses two rectangular copper sheets. Furthermore, based on the equivalent transmission line theory, the upper copper sheet is equivalent to an upper inductor L connected in series. top Upper capacitor C top Upper layer resistor R top The via is equivalent to an inductor Lvia; the underlying RLC switching circuit layer also includes a matching structure, which is equivalent to an inductor Lmetal.

[0051] Furthermore, the underlying RLC switching circuit layer includes several radio frequency (RF) switches and LC circuits or resistors embedded between the RF switches. By switching between different LC circuits or resistors using the RF switches, the metasurface unit can be freely tuned to the phase at a certain frequency. The LC circuits embedded between the RF switches are used to control the phase of electromagnetic waves, while the resistors embedded between the RF switches absorb electromagnetic waves.

[0052] It should be noted that this invention achieves amplitude and phase modulation of electromagnetic waves via the metasurface by performing multi-dimensional reconfigurable analysis of the underlying extended circuit, such as... Figure 2 As shown in (a), the upper metal patch receives electromagnetic waves from free space, transmits them through metal vias to the lower expansion circuit, and then, after being modulated by the lower expansion circuit, transmits them back to free space, thus achieving precise control of the electromagnetic waves. Figure 2 In (c), the entire metasurface unit is treated as a load in the transmission line equation, and the upper unit structure of the metasurface unit with a specific function can be equivalent to L. top and C top The underlying expansion circuit uses an RF switch to switch between the CL circuit (phase modulation) and the R circuit (amplitude modulation). Its specific embedded structure diagram is shown below. Figure 2 As shown in (d) in the figure.

[0053] The equivalent circuit structure of the entire metasurface unit can be approximated as: the fixed part (ANT) and the embedded part of the metasurface unit.

[0054] The inverting amplifier includes: a matching circuit and a DC blocking circuit (in this example, a DC blocking capacitor C is used). bias-tee ), amplifier circuit, and isolation circuit (in this example, an isolation inductor L is used). bias-tee The bias circuit is located between the matching circuit and the low-power metasurface unit, or between the matching circuit and the amplification circuit. The amplification circuit is connected to the bias circuit via the AC blocking circuit.

[0055] Furthermore, the matching circuit adopts an LC circuit, including a first inductor L1 connected in series and a first capacitor C1 connected in parallel. The first inductor L1 and the first capacitor C1 form a frequency selection circuit for the backscattering amplifier, thereby determining the operating frequency of the entire circuit.

[0056] Furthermore, the amplifier circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor Q1, and a second transistor Q2. One end of the first resistor R1 is connected to one end of the fourth resistor R4 and the collector of the first transistor Q1; the other end of the first resistor R1 is connected to the base of the first transistor Q1 and the collector of the second transistor Q2; the emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2 and one end of the second resistor R2; the base of the second transistor Q2 is connected to the other end of the fourth resistor R4 and one end of the third resistor R3; the other end of the second resistor R2 is connected to the other end of the third resistor R3 and grounded.

[0057] It should be noted that the first transistor Q1 and the second transistor Q2 can be either NPN or PNP transistors. By changing the operating state of the two transistors, they are positioned in the amplification region but not fully conducting. By decreasing the bias voltage of the second transistor Q2 and increasing the bias voltage of the first transistor Q1, the overall circuit possesses a nonlinear negative resistance region similar to that of a tunneling diode, achieving a nonlinear negative resistance region even at bias voltages below 1V. This backscattering amplifier circuit allows adjustment of the static operating point of the nonlinear negative resistance region by adjusting the resistor values, meaning that the power consumption and the negative resistance value of the backscattering amplifier circuit are adjustable. Compared to the negative impedance characteristics of a tunneling diode under low voltage bias conditions, it features large-scale integration. Furthermore, this inverting amplifier does not amplify RF signals in a single channel like a two-port amplifier, which can, to some extent, avoid self-oscillation.

[0058] For example, in this instance, the specific circuit of the inverting amplifier is as follows: Figure 3 As shown, the input / output signals of the low-power metasurface unit are equivalent to RF in / out and R0 connected in series with it. The input / output signal terminals of the low-power metasurface unit are connected to a matching circuit via a DC blocking capacitor C2. The matching circuit is connected to an amplifier circuit, which is grounded via a bias inductor L1. The matching circuit uses a first capacitor C1 and a first inductor L1 connected in series. The amplifier circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor Q1, and a second transistor Q2. One end of the first resistor R1 is connected to one end of the fourth resistor R4 and the collector of the first transistor Q1. The other end of the first resistor R1 is connected to the base of the first transistor Q1 and the collector of the second transistor Q2. The emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2 and one end of the second resistor R2. The base of the second transistor Q2 is connected to the other end of the fourth resistor R4 and one end of the third resistor R3. The other end of the second resistor R2 is connected to the other end of the third resistor R3 and grounded.

[0059] It should be noted that in V CC Under the bias, the inverting amplifier is a low-power, high-gain reflective amplifier, an amplifier circuit with nonlinear negative resistance characteristics. The entire backscattering amplifier circuit is in the nonlinear negative resistance region, and its IV curve is as follows. Figure 4 As shown. By adjusting V CCAt a voltage of 0.87V, the total current of the entire backscatter amplifier circuit is 7.38uA, while the negative resistance is -627.6Ω. At this quiescent operating point, the total power consumption is 64uW, achieving a gain exceeding 30dB. L2 is an isolated AC circuit. The entire backscatter amplifier provides stable amplification for RF signals with input power ranging from -90dBm to -10dBm, which is highly suitable for small signals received by low-power metasurfaces.

[0060] Example 1

[0061] This embodiment 1 provides a low-power common-gain tunable metasurface based on nonlinear negative resistance. The invariant part of the low-power metasurface unit can be regarded as a fixed antenna ANT for transmitting and receiving signals. The invariant part of the metasurface includes the upper structure, upper dielectric, metal ground, and lower dielectric of the low-power metasurface unit. The electromagnetic signal received by the low-power metasurface unit is transmitted to the RF switch terminal. The RF switch selects the phase modulation circuit, and after passing through the matching circuit, it enters the backscattering amplifier circuit under low voltage bias, thereby amplifying the electromagnetic signal. After reflection and backscattering, the signal passes through the upper copper sheet of the metasurface unit through a via and is then radiated into free space, thereby realizing the gain and phase modulation of the electromagnetic wave.

[0062] Specifically, such as Figure 5 As shown, in this example, the bottom RLC embedded circuit layer includes a single-pole four-throw switch SP4T, a first LC circuit embedded between the first RF switches RF1, a second LC circuit embedded between the second RF switches RF2, a third LC circuit embedded between the third RF switches RF3, and a fourth LC circuit embedded between the fourth RF switches RF4.

[0063] Furthermore, embedding different LC circuits can achieve different phase changes of the entire metasurface unit for free-space waves. Based on the transmission line equivalent circuit model analysis, the expressions for the impedance Z(C,L,f) and electromagnetic wave reflection coefficient Γ(C,L,f) of the low-power common-gain tunable metasurface based on nonlinear negative resistance provided in this example are as follows:

[0064]

[0065]

[0066] In the formula, Z0 represents the free space impedance, which is generally taken as 377Ω or 120π.

[0067] In this example, the upper structure in the invariant part of the metasurface is equivalent to C. top =0.32pF, L topWhen =5.2nH, according to the above formula, it can be calculated that when the embedded (L, C) combination values ​​are (2,2), (3.6,3.6), (4.3,4.3), and (9,9), phase changes of 0, 90°, 180°, and 270° can be achieved respectively. At this time, the units of L and C are (nH, pF).

[0068] Of course, this RF switch selection circuit can also be implemented by selecting different phase delay lines, which serves as a supplement to the main phase modulation scheme.

[0069] Example 2

[0070] Compared to Embodiment 1, the specific difference lies only in that the bottom RLC embedded circuit layer includes several RF switches, a first resistor embedded between the first RF switches RF1, a second resistor embedded between the second RF switches RF2, a third resistor embedded between the third RF switches RF3, a fourth resistor embedded between the fourth RF switches RF4, ..., and an Nth resistor embedded between the Nth RF switches RFN. This Embodiment 2 achieves electromagnetic signal absorption by embedding different resistance values ​​in the bottom extended circuit.

[0071] Specifically, such as Figure 6 As shown, in this example, the invariant part of the entire metasurface can be represented by the transmission line model, where the upper structure, vias, and the underlying metal structure are respectively equivalent to R. top C top L top L via L metal The mixed connection, and the underlying embedded circuit achieves different absorption effects by selecting different embedded resistance values.

[0072] Based on the equivalent transmission line model theory, when the RF switch selects a resistor, the expression for the impedance Z(R,f) of the low-power common-gain tunable metasurface based on nonlinear negative resistance is as follows:

[0073]

[0074] In the formula, j represents an imaginary number, f represents the frequency, and R represents the resistance between the embedded RF switches.

[0075] The expression for the absorption rate A of electromagnetic waves based on a low-power common-gain tunable metasurface with nonlinear negative resistance is as follows:

[0076] A = 1 - |Γ(R,f)| 2

[0077] In the formula, Γ(R,f) represents the reflection coefficient of the electromagnetic wave, and its expression is as follows:

[0078]

[0079] In the formula, Z0 represents the free space impedance, which is generally taken as 377Ω or 120π. It represents the reflected phase of an electromagnetic wave.

[0080] Furthermore, the entire metasurface unit will exhibit different absorption effects due to varying embedding resistance values. The upper structure within the invariant portion of the metasurface is equivalent to C. top =0.32pF, L top =5.2nH, when the Rtop of the upper structure is 10-500Ω, the absorption effect of the lower extension circuit with different embedded resistors is as follows: Figure 6 (c) in the middle.

[0081] Example 3

[0082] Compared with Embodiment 1 and Embodiment 2, the only difference is that the bottom RLC switching circuit layer includes several radio frequency switches, as well as LC circuits or resistors embedded between the radio frequency switches and combinations thereof. Specifically, the bottom RLC switching circuit layer includes several radio frequency switches, a first LC circuit embedded between the first radio frequency switch RF1, a second LC circuit embedded between the second radio frequency switch RF2, a third LC circuit embedded between the third radio frequency switch RF3, a fourth LC circuit embedded between the fourth radio frequency switch RF4, a first resistor embedded between the fifth radio frequency switch RF5, a second resistor embedded between the sixth radio frequency switch RF6, ..., and an Nth resistor embedded between the Nth radio frequency switch RFN.

[0083] This implementation example can simultaneously achieve phase modulation and scattering amplification of electromagnetic waves in Example 1 and absorption of electromagnetic waves in Example 2.

[0084] Specifically, such as Figure 7 As shown, in this example, the invariant part of the entire metasurface can be represented by the transmission line model, where the upper structure, vias, and the underlying metal structure are respectively equivalent to R. top C top L top L via L metal The hybrid connection, and the underlying embedded circuit, by selecting to embed different phase modulation amplifier circuits or resistor circuits, the specific working process is the same as in Embodiment 1 and Embodiment 2, to realize phase modulation and scattering amplification or absorption of electromagnetic waves.

[0085] In summary, compared to the difficulty in balancing structural and design complexity in PIN diode-based metasurface designs, and the high power consumption and overly complex bias circuits of varactor diode-based metasurface designs, the low-power, common-gain adjustable metasurface based on nonlinear negative resistance implemented in this invention, using low-power components such as RF switches, capacitors, and inductors, not only achieves functionality comparable to traditional metasurfaces in terms of design complexity but also significantly reduces overall power consumption. Furthermore, the low-power, high-gain backscattering amplifier proposed in this invention, through its backscattering amplification function of RF signals, can avoid self-oscillation to a certain extent. Simultaneously, the amplification characteristics of this backscattering amplifier can be tuned by adjusting the bias or resistance value, and the power consumption of the entire amplification circuit is only in the microwatt range (e.g., ...). Figure 4 As shown, it only has a gain effect of about 30dB for small signals (around 100μW).

[0086] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only.

[0087] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A low-power, common-gain tunable metasurface based on nonlinear negative resistance, characterized in that, include: Low-power metasurface unit and backscattering amplifier connected in series therewith; The low-power metasurface unit includes, from top to bottom, an upper copper sheet, an upper dielectric, a metal ground, a lower dielectric, and a bottom RLC switching circuit layer; wherein, the upper metal sheet is connected to the bottom RLC switching circuit through vias; the bottom RLC switching circuit layer includes several radio frequency switches, and LC circuits or resistors embedded between the radio frequency switches; The backscattering amplifier includes: a matching circuit, a DC blocking circuit, and an amplification circuit. The DC blocking circuit is disposed between the matching circuit and the low-power metasurface unit or between the matching circuit and the amplification circuit. The amplification circuit is connected to the bias circuit via an AC blocking circuit. The low-power metasurface unit receives electromagnetic signals, which are transmitted to the bottom RLC switching circuit through the upper copper sheet and vias. After the LC circuit or resistor is selected by the RF switch, the electromagnetic signal is amplified by the matching circuit and then reflected. After the LC circuit or resistor is selected by the RF switch, the signal is transmitted to the upper copper sheet through vias and then radiated into free space.

2. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 1, characterized in that, The shape of the upper copper sheet is selected from square, rectangle, polygon, and circle.

3. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 1 or 2, characterized in that, The upper copper sheet is equivalent to an upper inductor L connected in series. top Upper capacitor C top Upper layer resistor R top A through-hole is equivalent to an inductor L. via The underlying RLC switching circuit layer also includes a matching structure, which is equivalent to an inductor L. metal .

4. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 1, characterized in that, The DC blocking circuit uses a DC blocking capacitor, and the AC blocking circuit uses an AC blocking inductor.

5. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 1, characterized in that, The underlying RLC switching circuit layer includes several radio frequency switches, and the LC circuit or resistors embedded between the radio frequency switches include: The underlying RLC embedded circuit layer includes a single-pole four-throw switch SP4T, a first LC circuit embedded between the first RF switch RF1, a second LC circuit embedded between the second RF switch RF2, a third LC circuit embedded between the third RF switch RF3, and a fourth LC circuit embedded between the fourth RF switch RF4. By switching the RF switches to select different LC circuits, the phase modulation of electromagnetic waves can be achieved. or, The underlying RLC embedded circuit layer includes several radio frequency switches, a first resistor embedded between the first radio frequency switch RF1, a second resistor embedded between the second radio frequency switch RF2, a third resistor embedded between the third radio frequency switch RF3, a fourth resistor embedded between the fourth radio frequency switch RF4, ..., an Nth resistor embedded between the Nth radio frequency switch RFN. By switching the radio frequency switches, different resistors are selected to achieve the absorption of electromagnetic waves. or, The underlying RLC switching circuit layer includes several radio frequency switches, as well as LC circuits or resistors embedded between the radio frequency switches and combinations thereof. Specifically, the underlying RLC switching circuit layer includes several radio frequency switches, a first LC circuit embedded between the first radio frequency switch RF1, a second LC circuit embedded between the second radio frequency switch RF2, a third LC circuit embedded between the third radio frequency switch RF3, a fourth LC circuit embedded between the fourth radio frequency switch RF4, a first resistor embedded between the fifth radio frequency switch RF5, a second resistor embedded between the sixth radio frequency switch RF6, ..., an Nth resistor embedded between the Nth radio frequency switch RFN. By switching the radio frequency switches, different LC circuits or resistors are selected to achieve phase modulation or absorption of electromagnetic waves.

6. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 1, characterized in that, The matching circuit uses an LC circuit, and a frequency selection circuit for the backscattering amplifier is formed by a series capacitor and an inductor to determine the operating frequency of the circuit.

7. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 1, characterized in that, The amplifier circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor Q1, and a second transistor Q2. One end of the first resistor R1 is connected to one end of the fourth resistor R4 and the collector of the first transistor Q1. The other end of the first resistor R1 is connected to the base of the first transistor Q1 and the collector of the second transistor Q2. The emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2 and one end of the second resistor R2. The base of the second transistor Q2 is connected to the other end of the fourth resistor R4 and one end of the third resistor R3. The other end of the second resistor R2 is connected to the other end of the third resistor R3 and grounded.

8. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 7, characterized in that, The first transistor Q1 and the second transistor Q2 are NPN transistors or PNP transistors. The bias voltage of the first transistor Q1 is increased, while the bias voltage of the second transistor Q2 is decreased, so that the circuit has a non-linear negative resistance region under a bias voltage of less than 1V.

9. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 3, characterized in that, When the RF switch is an LC circuit, the expression for the impedance Z(C,L,f) of the low-power common-gain tunable metasurface based on nonlinear negative resistance is as follows: In the formula, j represents the imaginary number, f represents the frequency, L represents the inductance between the embedded RF switches, and C represents the capacitance between the embedded RF switches; The expression for the reflection coefficient Γ(C,L,f) of electromagnetic waves is as follows: In the formula, Z0 represents the free space impedance.

10. The low-power common-gain tunable metasurface based on nonlinear negative resistance according to claim 3, characterized in that, When the RF switch selects a resistor, the impedance Z(R,f) of the low-power common-gain tunable metasurface based on nonlinear negative resistance is expressed as follows: In the formula, j represents an imaginary number, f represents the frequency, and R represents the resistance between the embedded RF switches; The expression for the electromagnetic wave absorption rate A of the low-power common-gain tunable metasurface based on nonlinear negative resistance is as follows: A=1-|Γ(R,f)| 2 In the formula, Γ(R,f) represents the reflection coefficient of the electromagnetic wave, and its expression is as follows: In the formula, Z0 represents the free space impedance.

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