Active transmissive smart metasurface and supporting circuitry for this smart metasurface

Abstract

An active transmission type intelligent metasurface and a matching circuit applied to the intelligent metasurface, the circuit comprising: a receiving antenna for receiving an electromagnetic wave signal; a power amplification unit for amplifying the electromagnetic wave signal received by the receiving antenna; a phase coupling unit for modulating the amplified electromagnetic wave signal into electromagnetic wave signals with various phase differences; a phase selection unit for selecting an electromagnetic wave signal with a required phase difference from the electromagnetic wave signals with various phase differences; and a radiation antenna for radiating the electromagnetic wave signal with the corresponding phase difference; the intelligent metasurface comprises a plurality of active transmission intelligent metasurface units arranged periodically to form an N*M array, and each active transmission intelligent metasurface unit in the array comprises an active transmission circuit. The present application realizes the active amplification function which the existing transmission RIS structure does not have and has the 2-bit phase control function, and the present application has low design complexity, low deployment cost and good system performance.

Description

Technical Field

[0001] This invention relates to the field of wireless communication, specifically to an active transmissive smart metasurface and a supporting circuit for use with this smart metasurface. Background Technology

[0002] In the development of 6G communication technology, active and passive reconfigurable smart metasurfaces (RIS) play a crucial role. They optimize network performance by controlling the propagation path of wireless signals. Passive RIS rely on a large number of passive reflective elements to change the phase of the incident signal, requiring no external power supply and thus consuming almost no power. However, passive RIS has a major limitation: the "multiplicative fading" effect. This physical phenomenon causes signals reflected by the RIS to suffer significant path loss during propagation, especially in scenarios with strong direct channels. This effect significantly limits the improvement of system capacity. Multiplicative fading is an important concept in the field of wireless communication, especially when it comes to the application of reconfigurable smart metasurface (RIS) technology. This phenomenon usually occurs when using reflective elements to enhance or modify the path of wireless signals. In wireless communication, the propagation of signals from the transmitter to the receiver undergoes various forms of attenuation or fading. Fading can be divided into additive fading and multiplicative fading. Additive fading is mainly caused by environmental noise or interference, which affects the signal in an additive manner during signal transmission. In contrast, multiplicative fading is caused by the characteristics of the propagation medium, especially when the signal passes through multiple reflections or transmissions, each of which may introduce a certain amount of attenuation. These attenuation factors multiply and ultimately significantly affect the strength of the received signal.

[0003] Multiplicative fading is particularly pronounced in systems employing passive RIS (Resonance Receiver) systems. Passive RISs typically consist of multiple passive components that reflect the incident signal towards the target direction. In this process, the signal first travels from the transmitter to the RIS and then is reflected back to the receiver. Attenuation at each point along the path affects the signal, and these factors are mathematically multiplicative, hence the term multiplicative fading. Specifically, if the signal experiences attenuation on the path from the transmitter to the RIS and then again on the path from the RIS to the receiver, the total attenuation is the product of these two attenuation factors. The multiplicative fading effect often makes passive RISs ineffective in environments with strong direct links (the direct communication path between the transmitter and receiver). Even if the RIS provides some path gain, the significant attenuation due to multiplicative fading still limits system performance improvement. This is why RIS technology is particularly effective in scenarios with blocked or very weak direct links, where the gain provided by the RIS can more significantly improve communication quality. This effect significantly increases overall path loss, limiting the applicability of RIS in various communication scenarios. Furthermore, communication transmission via a transmissive RIS may introduce significant insertion losses, which in some cases can reach 5.7 dB or higher. Phase shift losses from electronic components also significantly limit the propagation distance of the RIS-assisted system. Compared to 1-bit controlled RIS systems, 2-bit designs exhibit better performance in sidelobe level control while maintaining low complexity. Recognizing these drawbacks, active RIS systems with signal amplification capabilities have become a new research topic for improving signal quality. Summary of the Invention

[0004] In view of the technical defects and drawbacks existing in the prior art, embodiments of the present invention provide a smart metasurface that overcomes or at least partially solves the above problems, and an active transmission circuit applied to the smart metasurface, the specific solution of which is as follows:

[0005] As a first aspect of the present invention, a supporting circuit for a smart metasurface is provided, the circuit comprising: a receiving antenna, a power amplification unit, a phase coupling unit, a phase selection unit, and a radiating antenna;

[0006] The receiving antenna is used to receive incident electromagnetic wave signals;

[0007] The power amplifier unit is used to amplify the electromagnetic wave signal received by the receiving antenna;

[0008] The phase coupling unit is used to modulate the amplified electromagnetic wave signal into electromagnetic wave signals with various phase differences.

[0009] The phase selection unit is used to select an electromagnetic wave signal with the desired phase difference from electromagnetic wave signals with various different phase differences.

[0010] The radiating antenna is used to radiate electromagnetic wave signals selected by the phase selection unit.

[0011] Furthermore, the power amplification unit includes a power amplification chip and a power amplifier power supply circuit. The power amplifier power supply circuit is used to supply power to the power amplification chip, and the power amplification chip is used to amplify the electromagnetic wave signal received by the receiving antenna.

[0012] Furthermore, the phase selection unit includes a multiplexer switch and a phase-shift control circuit. The multiplexer switch includes multiple control signal terminals. The phase-shift control circuit is used to input a high-level or low-level signal to each control signal terminal respectively. The multiplexer switch determines the conducting switch by detecting the combination of level signals of each control signal terminal.

[0013] Furthermore, the phase coupling unit is a four-phase coupler, which is used to modulate the amplified electromagnetic wave signal into four electromagnetic wave signals with different phase differences of 0°, 90°, 180° and 270° for output. The phase selection unit is used to select an electromagnetic wave signal with a desired phase difference from the four electromagnetic wave signals with different phase differences of 0°, 90°, 180° and 270°.

[0014] Furthermore, the phase selection unit includes a four-way selection switch and a phase shift control circuit. The four-way selection switch includes four independent switches. The four electromagnetic wave signals with different phase differences are respectively connected to the radiating antenna through the four independent switches. The phase shift control circuit is used to control one of the four independent switches to close, so that the electromagnetic wave signal with the corresponding phase difference is radiated through the radiating antenna.

[0015] Furthermore, the four-way selection switch is a four-way selection switch of model MXD8641H. The four-way selection switch includes two control signal terminals, namely a first control signal terminal and a second control signal terminal. The phase shift control circuit is used to input high-level or low-level signals to the first control signal terminal and the second control signal terminal. The four-way selection switch determines the switch to be turned on by detecting the combination of the level signals of the two control signal terminals.

[0016] Furthermore, the first switch of the four-way selection switch is used to output an electromagnetic wave signal with a 0° phase difference, the second switch is used to output an electromagnetic wave signal with a 90° phase difference, the third switch is used to output an electromagnetic wave signal with a 180° phase difference, and the fourth switch is used to output an electromagnetic wave signal with a 270° phase difference.

[0017] The four-way selection switch determines which switch is active by detecting the combination of the level signals from the two control signal terminals.

[0018] When both the first control signal terminal and the second control signal terminal are at a high level, the first switch is turned on.

[0019] When the level signal of the first control signal terminal is low and the level signal of the second control signal terminal is high, the second switch is turned on.

[0020] When the level signals of the first control signal terminal and the second control signal terminal are both low, the third switch is turned on;

[0021] When the level signal of the first control signal terminal is high and the level signal of the second control signal terminal is low, the fourth switch is turned on.

[0022] As a second aspect of the present invention, an active transmissive smart metasurface is provided, the active transmissive smart metasurface comprising a plurality of active transmissive smart metasurface units, the plurality of active transmissive smart metasurface units being periodically arranged to form an N*M array, each of the active transmissive smart metasurface units in the array comprising an active transmissive circuit applied to the smart metasurface as described above; the receiving antenna is disposed on the upper surface of the active transmissive smart metasurface unit, and the radiating antenna is disposed on the lower surface of the active transmissive smart metasurface unit.

[0023] Furthermore, both the receiving antenna and the radiating antenna are metal patch antennas, and the receiving antenna and the radiating antenna respectively form an N*M metal patch antenna array on the upper and lower surfaces of the smart metasurface, corresponding to the active transmission smart metasurface unit array.

[0024] Furthermore, the active transmission smart metasurface unit has a multi-layer structure design, comprising, from top to bottom:

[0025] The first component layout layer is used to lay out the receiving antenna and power amplifier unit;

[0026] The first dielectric layer includes a first dielectric substrate;

[0027] Metallic strata;

[0028] The second dielectric layer includes a second dielectric substrate;

[0029] The second element layout layer is used to lay out phase coupling units, phase selection units, and radiating antennas.

[0030] Furthermore, the receiving antenna, power amplification unit, phase coupling unit, phase selection unit, and radiating antenna are sequentially connected via microstrip lines. Each layer of the active transmission smart metasurface unit is provided with vias through which the microstrip lines pass. The microstrip line at the output of the power amplification unit of the first layer passes through the vias and connects to the input of the phase coupling unit of the ninth layer.

[0031] The present invention has the following beneficial effects:

[0032] To address the high insertion loss and multiplicative fading effect inherent in existing transmissive RIS structures, this invention proposes a smart metasurface and an active transmissive circuit design applied to the smart metasurface. It achieves a 2-bit phase shift function through a four-phase coupler and a four-way selection switch, while integrating a power amplifier chip to realize active amplification functionality not found in existing transmissive RIS structures. This further improves the communication quality of the transmissive smart metasurface-assisted wireless communication system. Furthermore, this invention features lower design complexity, lower deployment cost, and better system performance. Attached Figure Description

[0033] Figure 1 An active transmission circuit applied to a smart metasurface is provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the selection switch control signal setting provided in an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of the upper surface of an active transmission smart metasurface unit provided in an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of the lower surface of an active transmission smart metasurface unit provided in an embodiment of the present invention;

[0037] Figure 5 The active transmission smart metasurface unit structure parameters provided in the embodiments of the present invention

[0038] Figure 6 This is a schematic diagram of an active transmission smart metasurface unit stack provided in an embodiment of the present invention;

[0039] Figure 7 The simulation results of the active transmission intelligent metasurface provided in the embodiments of the present invention are shown in the figure.

[0040] Figure 8 A schematic diagram of an evaluation board for an active transmission intelligent metasurface phase-shifting amplifier circuit provided in an embodiment of the present invention;

[0041] Figure 9This is a schematic diagram of phase testing on an evaluation board for an active transmission intelligent metasurface phase-shifting amplifier circuit provided in an embodiment of the present invention.

[0042] Figure 10 A schematic diagram of the return loss and isolation test of the evaluation board of the active transmission intelligent metasurface phase-shifting amplifier circuit provided in an embodiment of the present invention;

[0043] Figure 11 A schematic diagram of the phase change measurement of the active transmission intelligent metasurface phase-shifting amplifier circuit under different power amplifier supply currents provided in an embodiment of the present invention.

[0044] Figure 12 This is a top view of the active transmission smart metasurface array provided in an embodiment of the present invention;

[0045] Figure 13 This is a bottom view of an active transmission smart metasurface array provided in an embodiment of the present invention;

[0046] Figure 14 This is a schematic diagram of the phase modulation test of an active transmission smart metasurface array provided in an embodiment of the present invention;

[0047] Figure 15 This is a schematic diagram of the amplitude modulation test of an active transmission intelligent metasurface array provided in an embodiment of the present invention;

[0048] Figure 16 This is a schematic diagram of beamforming test for an active transmission smart metasurface array provided in an embodiment of the present invention;

[0049] Figure 17 This is a schematic diagram comparing the present invention with existing designs, provided for an embodiment of the invention. Detailed Implementation

[0050] 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 a part of the present invention, and not all of the 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.

[0051] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “including,” “comprising,” or “containing,” and similar terms mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0052] In the various figures, the same elements are represented by similar reference numerals. For clarity, not all parts in the figures are drawn to scale. Furthermore, some well-known parts may not be shown in the figures.

[0053] Many specific details of this disclosure are described below to provide a clearer understanding of it. However, as those skilled in the art will understand, this disclosure may be implemented without following these specific details.

[0054] Figure 1 A supporting circuit for smart metasurfaces provided in this embodiment of the invention, such as... Figure 1 As shown, it mainly includes: a receiving antenna, a power amplification unit, a phase coupling unit, a phase selection unit, and a radiating antenna. The phase coupling unit and the phase selection unit together constitute a phase shifting circuit.

[0055] The receiving antenna is used to receive incident electromagnetic wave signals;

[0056] The power amplifier unit is used to amplify the electromagnetic wave signal received by the receiving antenna;

[0057] The phase coupling unit is used to modulate the amplified electromagnetic wave signal into electromagnetic wave signals with various phase differences.

[0058] The phase selection unit is used to select an electromagnetic wave signal with the desired phase difference from electromagnetic wave signals with various different phase differences.

[0059] The radiating antenna is used to radiate electromagnetic wave signals selected by the phase selection unit.

[0060] To address the high insertion loss and multiplicative fading effect inherent in existing transmission RIS structures, this invention proposes a supporting circuit design for smart metasurfaces. By integrating phase coupling and phase selection units, various phase shifting functions can be achieved. By integrating a power amplifier chip, active amplification functionality not available in existing transmission RIS structures is realized, thereby improving the communication quality of wireless communication systems assisted by transmission smart metasurfaces. Furthermore, this invention features lower design complexity, lower deployment costs, and better system performance.

[0061] In some embodiments, the power amplification unit includes a power amplification chip and a power amplifier power supply circuit. The power amplifier power supply circuit is used to supply power to the power amplification chip, and the power amplification chip is used to amplify the electromagnetic wave signal received by the receiving antenna. Optionally, the power amplification unit adopts a SKY65017-70LF power amplifier from SKYWorks. The maximum supply current of the power amplifier is 120mA and the maximum voltage is 5.5V.

[0062] refer to Figure 1 The power amplifier power supply circuit includes inductors PA_L1, PA_L2, PA_L3 and capacitor PA_C4. The power supply Pa_Vdd is connected to the output terminal of the power amplifier chip in sequence through inductors PA_L3, PA_L2 and PA_L1 to supply power to the power amplifier chip. The power supply Pa_Vdd is also grounded through capacitor PA_C4 to filter the AC component in the power supply.

[0063] In some embodiments, the phase coupling unit is a four-phase coupler, which is used to modulate the amplified electromagnetic wave signal into four electromagnetic wave signals with different phase differences of 0°, 90°, 180° and 270° for output. The phase selection unit is used to select an electromagnetic wave signal with a desired phase difference from the four electromagnetic wave signals with different phase differences of 0°, 90°, 180° and 270° and send it to the radiating antenna.

[0064] In the above embodiment, the four-phase coupler is a QF2500Q06 model. The input of the four-phase coupler receives the amplified electromagnetic wave signal and independently generates four signals with different phase differences of 0°, 90°, 180° and 270° based on the amplified electromagnetic wave signal, and outputs them through four output channels respectively.

[0065] In some embodiments, the phase selection unit includes a four-way selection switch and a phase shift control circuit. The four-way selection switch includes four independent switches. The four electromagnetic wave signals with different phase differences are respectively connected to the radiating antenna through the four independent switches. The phase shift control circuit is used to control one of the four independent switches to close, so that the electromagnetic wave signal with the corresponding phase difference is radiated through the radiating antenna.

[0066] Optionally, the four-way selection switch is a four-way selection switch of model MXD8641H, also known as an SP4T switch. The four-way selection switch includes two control signal terminals, namely a first control signal terminal and a second control signal terminal. The phase shift control circuit is used to input high-level or low-level signals to the first control signal terminal and the second control signal terminal. The four-way selection switch determines the switch to be turned on by detecting the combination of the level signals of the two control signal terminals.

[0067] Specifically, the first switch of the four-way selection switch is used to output an electromagnetic wave signal with a 0° phase difference, the second switch is used to output an electromagnetic wave signal with a 90° phase difference, the third switch is used to output an electromagnetic wave signal with a 180° phase difference, and the fourth switch is used to output an electromagnetic wave signal with a 270° phase difference.

[0068] The four-way selection switch determines which switch is active by detecting the combination of the level signals from the two control signal terminals.

[0069] When both the first control signal terminal and the second control signal terminal are at a high level, the first switch is turned on.

[0070] When the level signal of the first control signal terminal is low and the level signal of the second control signal terminal is high, the second switch is turned on.

[0071] When the level signals of the first control signal terminal and the second control signal terminal are both low, the third switch is turned on;

[0072] When the level signal of the first control signal terminal is high and the level signal of the second control signal terminal is low, the fourth switch is turned on.

[0073] refer to Figure 1As shown, the phase-shift control circuit includes four input signals: Switch_Vdd, Vcc1, Vcc2, and Vcc3. Switch_Vdd is a power supply signal, and Vcc1 is a normal signal that is always set to a low level. The phase-shift control circuit inputs high-level or low-level signals to the first control signal terminal and the second control signal terminal through Vcc2 and Vcc3. For example, when Vcc2 is high, the corresponding first control signal terminal is a high-level signal, and when Vcc3 is high, the corresponding second control signal terminal is a high-level signal.

[0074] In some embodiments, the high level is a 3V level signal, defined as 1, and the low level is a 0.3V level signal, defined as 0. Phase adjustment is achieved by setting the control signal terminals to high or low levels while maintaining a constant control current of 0.5μA. Different phase signal outputs are achieved by changing the high and low levels of Vcc1, Vcc2, and Vcc3, as detailed in the specific settings. Figure 2 As shown, when Vcc1, Vcc2, and Vcc3 are 011, the output phase is 0°; when Vcc1, Vcc2, and Vcc3 are 001, the output phase is 90°; when Vcc1, Vcc2, and Vcc3 are 000, the output phase is 180°; and when Vcc1, Vcc2, and Vcc3 are 010, the output signal phase is 270°.

[0075] In the above embodiment, Vcc1 is kept constant at 0, i.e. low level. Therefore, only the levels of Vcc2 and Vcc3 change from high to low. By combining the level changes of Vcc2 and Vcc3, four types of phase difference signal outputs are achieved, thereby realizing the 2-bit phase shift function.

[0076] As another embodiment of the present invention, an active transmissive smart metasurface is also provided. The active transmissive smart metasurface includes a plurality of active transmissive smart metasurface units, which are periodically arranged to form an N*M array. Each active transmissive smart metasurface unit in the array includes an active transmissive circuit applied to the smart metasurface as described above. The receiving antenna is disposed on the upper surface of the active transmissive smart metasurface unit (the upper surface can also be described as the front or signal receiving surface), and the radiating antenna is disposed on the lower surface of the active transmissive smart metasurface unit (the lower surface can also be described as the back, signal radiating surface, or signal transmitting surface).

[0077] The receiving antenna and the radiating antenna are both metal patch antennas, and the receiving antenna and the radiating antenna form N*M metal patch antenna arrays on the upper and lower surfaces of the smart metasurface, respectively, corresponding to the active transmission smart metasurface unit array.

[0078] Figure 3-4 This is a schematic diagram of the upper and lower surfaces of the active transmission smart metasurface unit provided in an embodiment of the present invention, with reference to... Figure 3 As shown, the upper surface of the active transmissive smart metasurface unit is provided with a receiving patch (i.e., a metal patch antenna serving as a receiving antenna) and a power amplification unit, as shown in the reference diagram. Figure 4 The active transmissive smart metasurface unit has a phase coupling unit, a phase selection unit, and a radiating patch (i.e., a metal patch antenna that serves as a radiating antenna) arranged on its lower surface. The receiving antenna, power amplification unit, phase coupling unit, phase selection unit, and radiating antenna are sequentially electrically connected via microstrip connecting lines. The microstrip connecting lines pass through vias from the upper surface to the lower surface. The four phase couplers and the four-way selection switch are connected by four microstrip lines of equal length.

[0079] Active transmission intelligent metasurface unit structure parameters are as follows Figure 5 As shown.

[0080] like Figure 6 As shown, in some embodiments, the present invention also provides a nine-layer stacked structure, which comprises, from top to bottom:

[0081] The first layer is the first component layout layer, which is used to lay out the receiving antenna and the power amplification unit. It includes N*M metal patch antenna arrays as receiving antennas, and the same number of power amplification units that correspond one-to-one with the metal patch antennas.

[0082] The second layer is the first semi-cured layer, which includes a first semi-cured sheet for bonding between different layers of the circuit board. Its thickness is 0.2108mm. The first layer structure and the third layer structure are located on the upper and lower surfaces of the first semi-cured sheet, respectively.

[0083] The third layer is the first dielectric layer, which includes the first dielectric board, and its material is epoxy glass cloth laminate (FR-4) with a thickness of 0.6mm;

[0084] The fourth layer is the upper metal floor layer, which includes the upper metal floor.

[0085] The fifth layer is the second semi-cured layer, which includes a second semi-cured sheet for bonding between the upper and lower metal flooring. Its thickness is 0.2028mm. The upper and lower surfaces of the second semi-cured sheet are the upper and lower metal flooring layers, respectively.

[0086] The sixth layer is the lower metal ground layer, including the lower metal floor;

[0087] The seventh layer is the second dielectric layer, which includes a second dielectric board. Its material is epoxy glass cloth laminate (FR-4) with a thickness of 0.6mm.

[0088] The eighth layer is the third semi-cured layer, which includes the third semi-cured sheet and is used for bonding between different layers of the circuit board. Its thickness is 0.2108mm. The seventh and ninth layer structures are located on the upper and lower surfaces of the third semi-cured sheet, respectively.

[0089] The ninth layer is the second component layout layer: it is used to lay out phase coupling units, phase selection units and radiating antennas, including N*M metal patch antenna arrays as radiating antennas, and the same number of phase coupling units, phase selection units and radiating antennas that correspond one-to-one with the metal patch antennas.

[0090] It should be noted that the stacked structure may also have other hierarchical forms, and is not limited to those provided in the embodiments of the present invention. The stacked structure provided in the embodiments is mainly used to support the active transmissive smart metasurface unit described in the present invention. The inventive point of the present invention lies in the active transmissive smart metasurface unit. Any stacked structure that can deploy the active transmissive smart metasurface unit described in the present invention is within the protection scope of the present invention.

[0091] The following are the simulation results of this invention:

[0092] The simulation was performed using the electromagnetic simulation software Ansys Electronics Desktop 2021R2.

[0093] The upper excitation surface is set to Flopuet port 1 to simulate incident wave excitation; the lower excitation surface is set to Flopuet port 2 to receive transmitted electromagnetic waves; the perimeter of the element is set to periodic boundary conditions to simulate an infinitely large active transmission smart metasurface array structure. The simulation center frequency is f = 2.6 GHz. The simulation results of the active transmission smart metasurface are as follows: Figure 7 As shown, the return loss of the incident wave is within the band (frequency range of 2.57 GHz to 2.62 GHz). The active transmission type RIS always maintains a return loss below -4 dB, and the insertion loss remains below -12 dB within this frequency range.

[0094] The following are the test results of this invention, mainly including the following aspects of the test:

[0095] Phase-shift amplifier circuit test:

[0096] To verify the reliability of the cascaded components selected above, this invention designs an evaluation circuit, such as... Figure 8As shown. The input RF signal passes sequentially through a power amplifier, a four-phase coupler, and an SP4T switch before being output. According to the official technical manual, the SKY65017-70LF power amplifier provides 20dB of signal enhancement, effectively compensating for the attenuation caused by the introduction of RIS in the transmission system and the electronic components used in the design. The maximum supply current of the power amplifier is 120mA, and the maximum voltage is 5.5V. Under actual conditions, the maximum gain provided by the power amplifier is 16dB. The positive supply voltage Vcc is connected to pin 3 of the amplifier through a decoupling network consisting of PA_C4, PA_L1, PA_L2, and PA_L3.

[0097] A phase control method based on SP4T switch control signals is used. The output state of the SP4T switch is determined by three control signals (Vcc1, Vcc2, and Vcc3). By setting the control signals to a high level (3V, defined as 1) or a low level (0.3V, defined as 0), phase adjustment is achieved while maintaining a constant control current of 0.5μA. The phase adjustment is not directly related to the control current but is determined by the high or low level of the control signals, thus achieving independent control of phase and current. In the experiment, the control signals are initially set to 011, defined as the reference state, corresponding to the 0° phase of the phase shift circuit output signal, as shown below. Figure 2 As shown, this setting provides a reference for subsequent phase comparisons. Subsequently, the control signal was adjusted to 001, and it was observed that the phase difference of the output signal relative to the reference state was close to 90°, as... Figure 9 As shown. This result demonstrates that the phase-shift circuit effectively achieves a quarter-cycle phase shift under this control signal. Furthermore, to comprehensively evaluate the performance of the phase-shift circuit, the control signal was changed sequentially to 000 and 010. Measurements under these settings show that, within the band of interest, the phase difference between the output signal and the reference phase stabilizes at approximately 180° and 270°, respectively. This observation confirms the stability and reliability of the phase-shift circuit under different control signals and demonstrates its accuracy in achieving the predetermined phase change. Measurements on the evaluation board also show that the phase-shift amplifier circuit... Figure 10 It exhibits good return loss and high isolation. At 2.6GHz, the phase curve of the evaluation board output was obtained by adjusting the supply current of the power amplifier, as shown in the figure. Figure 11 As shown, the amplification and phase-shifting circuits maintained good phase consistency at different active gain levels, with a phase error of less than 8°.

[0098] Test environment for active transmission intelligent metasurface arrays:

[0099] Design of active transmissive RIS arrays, such as Figure 12 and Figure 13As shown. The overall structure of the array is a 310×310 mm FR-4 printed circuit board, employing a multilayer board structure consistent with the cell design. This structure consists of two 0.8 mm thick FR-4 substrates bonded together using a lamination process. The array is divided into upper and lower sections, containing a total of 16 independent active transmissive RIS cells. Each cell is equipped with independent control circuitry, including phase-shift control circuitry and power amplifier power supply circuitry. These circuits connect to two sockets on the top of the array and communicate with the control board at the rear via ribbon cables. This design allows for independent adjustment of the active gain and phase of each cell throughout the active transmissive RIS array.

[0100] The phase control capability and signal amplification efficiency of the proposed active transmissive RIS array were tested. The experiment was conducted in a microwave anechoic chamber. The test setup included two standard gain horn antennas, used as the transmitter and receiver respectively. An 8×4 active transmissive RIS array with 32 elements was placed on a central turntable within the anechoic chamber, allowing for multi-angle and directional measurements. The transmitting horn antenna was positioned vertically at the center of the receiving surface of the active transmissive RIS array, maintaining a distance of 60 cm to ensure vertical incidence and good beam coverage. The receiving horn antenna was on the same horizontal plane as the active transmissive RIS array and the receiver, and perpendicular to the radiating surface of the RIS array. The distance between the receiver and the active transmissive RIS array was 4 meters. This test setup allowed for a comprehensive and accurate evaluation of the performance of the active transmissive RIS array, particularly key technical indicators such as phase control and signal amplification, in a controlled and standardized environment.

[0101] In the testing of active transmission smart metasurface arrays, a fast beamforming algorithm with low training / feedback overhead was applied. As a blind beamforming technique, this algorithm requires no additional channel information or user location data; instead, it adjusts the phase configuration solely based on the signal quality feedback provided by the receiver. It is particularly suitable for complex and dynamic communication environments, as it can quickly respond to environmental changes and adjust its beamforming coefficients accordingly. This algorithm aims to optimize signal reception quality in wireless communication systems by adjusting the transmission phase of the RIS (Radio Resonance Array). At the beginning of the process, an M*N complex matrix T0 is initialized, representing the initial state of the RIS transmission coefficients. After this initialization, the algorithm receives initial feedback from the receiver (RX) signal power p0 to establish a baseline for subsequent comparison and adjustment. Then, the algorithm proceeds in two main steps: horizontal search and vertical search.

[0102] Horizontal Search: This step focuses on each column of the RIS matrix. For each column (from column 1 to column N), the algorithm attempts to optimize the received signal power by changing the phase of the current column. Specifically, the algorithm increases the phase of the current column by 90° sequentially and then receives the signal power feedback p under the new configuration. nIf the new configuration maintains or improves the received power (p n-1 ≥p n If the change is positive, retain it; otherwise, revert to the previous configuration and maintain the original settings.

[0103] Vertical Search: After completing the horizontal search, the algorithm shifts its focus to each row of the RIS matrix. This process is similar to the horizontal search, but operates on rows rather than columns. Similarly, the algorithm attempts to find a better transmission coefficient configuration by changing the phase of each row, thereby enhancing the received signal power.

[0104] Through these iterative steps, the algorithm gradually optimizes the transmission coefficient configuration of the entire RIS array. Since the algorithm adjusts only one row or one column at a time, it gradually improves the signal-to-noise ratio (SNR) of the system without causing significant fluctuations in the received power. This step-by-step iterative method has very low complexity.

[0105] Active transmission intelligent metasurface array phase amplitude modulation test:

[0106] The active transmissive RIS array was set to full power operation to ensure accurate capability assessment. The control signals of each cell selection switch were sequentially switched to achieve a uniform phase change across the entire array. By sequentially switching four different states within the 2.55-2.57 GHz frequency range, the phase difference between these four specific states was close to 90°. This process verified the accuracy of the manufactured active transmissive RIS in phase control. Figure 14 As shown.

[0107] To analyze the changes in the RIS radiation pattern under different active gain levels, the receiver angle was adjusted to 0°. Then, the array's transmitted beam was directed to the receiver using the beamforming algorithm mentioned above. By controlling the input power, the response characteristics of the received signal at each power level were recorded. Subsequently, the radiation pattern of the RIS array under each power state was measured, as shown below. Figure 15 As shown, the measurement results demonstrate that the active transmissive RIS array possesses good active gain control capability. When the power amplifier chip's supply current is 2.6A, the power at the receiver reaches its peak. Compared to the minimum supply current of 0.01A, this peak represents a significant increase in received power of 11.9dB. Furthermore, the active transmissive RIS array exhibits progressively adjustable radiated power characteristics throughout the power adjustment process. This characteristic is crucial for achieving amplitude adjustment of each array element. This finding also proves the active transmissive RIS's ability to amplify incident signals, a capability not possessed by traditional RIS systems. Figure 15As shown, when the power amplifier operates at high current, providing significant active gain, the radiation pattern exhibits good directivity, with the maximum gain of the main lobe decreasing synchronously with the active gain. This ensures signal strength and consistency, maintaining good beam directivity. However, when the operating current is low, such as 0.2A and 0.01A, the pattern changes significantly because the reduction in active gain weakens beam consistency. Higher active gain helps maintain consistency, effectively concentrating energy on the main lobe. Lower gain can lead to beam dispersion, altering the main lobe shape and relatively increasing sidelobe levels. Furthermore, lower active gain makes the system more susceptible to nonlinear effects, further affecting beam shape and sidelobe levels.

[0108] Active transmission smart metasurface array beamforming test:

[0109] During testing, the position of the receiving antenna was first kept fixed. Then, the central turntable in the microwave anechoic chamber was rotated, starting from 0° and increasing in 10° increments until reaching 60°, covering seven different angles. The purpose was to comprehensively evaluate the beam control performance of the active transmission RIS system at various angles. At each specified angle, the optimization algorithm was run once. After optimization at each angle, without changing the array's state, a vector network analyzer was used to perform detailed measurements of the radiation pattern. Figure 16 The radiation pattern shown illustrates the beam control capability of the transmissive RIS system within a ±60° deflection range. The asymmetry in the radiation pattern can be attributed to factors such as imperfect symmetry in the array element structure, uneven element distribution, mutual coupling, and manufacturing errors. The system performs best at a 0° deflection angle, where the transmissive RIS is directly aligned with the target direction. In this state, it achieves the highest gain and a narrowest main lobe width of 14°. This combination of high gain and narrow main lobe width is an ideal response to the requirements of precise directional transmission.

[0110] As the receiver deflection angle increases, the system performance gradually decreases. When the deflection angle reaches a certain value, such as ±50°, the half-power beamwidth of the radiation pattern remains below 18°, demonstrating good directional control capability, and the gain performance only decreases by about 3.5dB. In addition, at a deflection angle of 60°, the half-power beamwidth increases to 22°. This phenomenon indicates that although the transmissive RIS maintains a certain beam control capability over a wide range, the directional and focusing capabilities decrease under extreme deflection angle conditions.

[0111] Overall, the measurement results confirm the system's high efficiency and reliability in precise phase control, signal amplification, adaptability, and dynamic communication environments. Furthermore, the results further highlight the significant potential of this technology in enhancing the performance of wireless communication systems and addressing the dual fading effects of traditional RIS (Reverse Isochronous Ratio).

[0112] exist Figure 17 This paper provides a detailed comparison between the present invention and existing designs. Compared to current active RIS designs, the proposed design exhibits significant advantages in several key aspects, particularly in terms of compact size and simplified structure. Specifically, our design achieves a reduction of over 90% in vertical dimensions. This not only makes the design more suitable for device miniaturization but also significantly reduces the production cost of the RIS array, thereby improving economic efficiency.

[0113] Furthermore, through in-depth searching of existing literature and databases, it was found that active transmission type RIS structure designs with active amplification function are relatively scarce in the current market. In view of this, the present invention largely fills the gap in this field and provides an innovative solution. This design provides more diverse options for the deployment of RIS in various application scenarios, greatly expands the application prospects of RIS technology, and thus has extremely high practical value and market potential.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A matching circuit applied to an intelligent metasurface, characterized in that, The intelligent metasurface is a transmissive intelligent metasurface, and the circuit comprises a receiving antenna, a power amplification unit, a phase coupling unit, a phase selection unit and a radiation antenna; The receiving antenna is configured to receive an electromagnetic wave signal; The power amplification unit is configured to amplify the electromagnetic wave signal received by the receiving antenna; The phase coupling unit is configured to modulate the amplified electromagnetic wave signal into electromagnetic wave signals with different phase differences; The phase selection unit is configured to select an electromagnetic wave signal with a required phase difference from the electromagnetic wave signals with different phase differences; The radiation antenna is configured to radiate the electromagnetic wave signal selected by the phase selection unit; The phase coupling unit is a four-phase coupler, which is configured to modulate the amplified electromagnetic wave signal into electromagnetic wave signals with four different phase differences of 0°, 90°, 180° and 270°, and the phase selection unit is configured to select an electromagnetic wave signal with a required phase difference from the electromagnetic wave signals with four different phase differences of 0°, 90°, 180° and 270°; The phase selection unit comprises a four-way selection switch and a phase shift control circuit, the four-way selection switch comprises four independent switches, the four electromagnetic wave signals with different phase differences are connected to the radiation antenna through the four independent switches, and the phase shift control circuit is configured to control one of the four independent switches to be closed, so that the electromagnetic wave signal with the corresponding phase difference is radiated by the radiation antenna; The four-way selection switch comprises two control signal terminals, namely a first control signal terminal and a second control signal terminal, the phase shift control circuit is configured to input high-level or low-level signals to the first control signal terminal and the second control signal terminal, and the four-way selection switch determines the switch to be turned on by detecting the level signal combination of the two control signal terminals.

2. The companion circuit for an intelligent metasurface of claim 1, wherein, The first switch of the four-way selection switch is configured to output an electromagnetic wave signal with a phase difference of 0°, the second switch is configured to output an electromagnetic wave signal with a phase difference of 90°, the third switch is configured to output an electromagnetic wave signal with a phase difference of 180°, and the fourth switch is configured to output an electromagnetic wave signal with a phase difference of 270°. The four-way selection switch determines the switch to be turned on by detecting the level signal combination of the two control signal terminals, and the determination is as follows: When the level signals of the first control signal terminal and the second control signal terminal are both high, the first switch is turned on; When the level signal of the first control signal terminal is low and the level signal of the second control signal terminal is high, the second switch is turned on; When the level signals of the first control signal terminal and the second control signal terminal are both low, the third switch is turned on; When the level signal of the first control signal terminal is high and the level signal of the second control signal terminal is low, the fourth switch is turned on.

3. An active transmissive metasurface, characterized in that, The active transmission type intelligent metasurface comprises a plurality of active transmission type intelligent metasurface units, the plurality of active transmission type intelligent metasurface units are periodically arranged to form an N*M array, each active transmission type intelligent metasurface unit in the array comprises a matching circuit applied to an intelligent metasurface as claimed in any one of claims 1-2; the receiving antenna is arranged on the upper surface of the active transmission type intelligent metasurface unit, and the radiating antenna is arranged on the lower surface of the active transmission type intelligent metasurface unit.

4. The active transmissive smart surface of claim 3, wherein, The receiving antenna and the radiating antenna are both metal patch antennas, and the receiving antenna and the radiating antenna respectively form N*M metal patch antenna arrays corresponding to the active transmission type intelligent metasurface unit array on the upper surface and the lower surface of the intelligent metasurface.

5. The active transmissive smart surface of claim 3, wherein, The active transmission type intelligent metasurface unit is a multi-layer structure design, comprising from top to bottom: a first element layout layer for laying the receiving antenna and the power amplification unit; a first dielectric layer comprising a first dielectric plate; a metal ground layer; a second dielectric layer comprising a second dielectric plate; a second element layout layer for laying the phase coupling unit, the phase selection unit and the radiating antenna.

6. The active transmissive smart surface of claim 3, wherein, The receiving antenna, the power amplification unit, the phase coupling unit, the phase selection unit and the radiating antenna are electrically connected in sequence through microstrip connection lines, each layer of the active transmission type intelligent metasurface unit is provided with a via hole for the microstrip connection line to pass through, and the microstrip connection line of the output end of the power amplification unit is connected with the input end of the phase coupling unit through the via hole.

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