A reflective 3-bit electronically-controlled programmable metasurface
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2024-08-06
- Publication Date
- 2026-07-10
AI Technical Summary
With the increase in the number of logic states, the complexity of the control circuit and the difficulty of implementation of existing multi-bit programmable metasurfaces increase, and it is also difficult to ensure that the phase and amplitude of all logic states meet the design requirements.
A reflective 3-bit electrically controlled programmable metasurface structure is designed, consisting of a top surface layer, a dielectric layer, a metal ground layer, and a bottom feed layer. A varactor diode is loaded to form a closed loop, and multi-phase control is achieved by independently controlling the bias voltage of the varactor diode.
It achieves reflection phase modulation performance exceeding 315°, has multi-phase control capability, is suitable for dynamic focusing and beam scanning, and has broad application prospects.
Smart Images
Figure CN118899671B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electromagnetic metasurface technology, specifically relating to a 3-bit electrically controlled programmable metasurface. Background Technology
[0002] Metasurfaces, as two-dimensional equivalents of metamaterials, are a novel type of two-dimensional electromagnetic material composed of periodic or aperiodic arrangements of subwavelength artificial units. By designing their unit structure, size, and array topology, metasurfaces can exhibit some exotic electromagnetic properties not found in naturally occurring materials. Furthermore, they exhibit low energy loss, are relatively simple to fabricate, and have a very broad application prospect.
[0003] While various functions of metasurfaces can be achieved through artificial design, the functions of passive metasurfaces are fixed once the structural design and fabrication process are complete, and their electromagnetic properties cannot be dynamically adjusted. To achieve flexible control, active metasurfaces can dynamically generate different functions as needed by introducing external stimuli. To achieve real-time control and switching of various functions, researchers have further constructed programmable metasurfaces where each unit can be independently controlled. In the microwave band, embedding voltage-driven elements such as varactor diodes or PIN diodes into programmable metasurface units to create electrically tunable metasurfaces is a promising direction. By adjusting the voltage applied to the programmable unit, the capacitance of the varactor diode and the switching state of the PIN diode can be changed, thus significantly altering the electromagnetic characteristics of the programmable unit. Then, by precisely determining the voltage distribution applied to different units of the metasurface, these metasurface devices can achieve flexible and dynamic control of electromagnetic waves. Compared to programmable metasurfaces loaded with PIN diodes, programmable metasurfaces loaded with varactor diodes are more convenient for multi-phase control and are expected to play an important role in future communication fields.
[0004] For multi-bit (e.g., 3-bit) programmable metasurfaces, the number of logic states increases significantly (e.g., a 3-bit cell has 8 logic states), which increases the complexity and implementation difficulty of the control circuit. Furthermore, ensuring that the phase and amplitude of all logic states meet design requirements is also a challenge. Summary of the Invention
[0005] The purpose of this invention is to solve the above-mentioned problems and provide an electrically controlled programmable metasurface structure for achieving 3-bit adjustable performance of the reflection phase within a specific frequency band.
[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is: a reflective 3-bit electrically controlled programmable metasurface structure, comprising a metasurface unit, wherein the metasurface unit includes a top patch, a first dielectric layer, an intermediate metal ground, an adhesive layer, a second dielectric layer, and a bottom feed layer. The top patch, the intermediate metal ground, and the bottom feed layer are all metal layers, and dielectric layers are respectively disposed between the top and intermediate layers, and between the intermediate and bottom layers. The top layer is composed of two metal patches, with a varactor diode loaded between the two metal patches to form a closed loop. The square metal patch of the top layer is connected to the metal ground through a metallized via, and the square metal patch is connected to the bottom feed layer through a metallized via.
[0007] Furthermore, both the first and second dielectric layers are made of Rogers RO4350B material, and the thicknesses of the first and second dielectric layers are set to 1.524 mm and 0.254 mm, respectively. The Rogers RO4350B dielectric layer has a relative permittivity of 3.48 and a loss angle of 0.0037.
[0008] Furthermore, the adhesive layer uses Rogers RO4450F material, which has a relative permittivity of 3.7, a loss angle of 0.004, and a thickness of 0.196 mm.
[0009] Furthermore, the metal ground is made of copper.
[0010] Furthermore, the metal through-hole, metal patch, and feed line are all made of copper.
[0011] Furthermore, the model number of the varactor diode is MGV125-08-0805.
[0012] According to the specific embodiments provided by the present invention, the beneficial effects of the present invention are:
[0013] 1. The reflective 3-bit electrically controlled programmable metasurface structure provided by this invention achieves a reflection phase modulation performance of more than 315°, thereby realizing 3-bit multi-phase control.
[0014] 2. The design of this invention has the advantages of low profile, light weight and easy processing, and has broad application prospects in areas such as anomalous reflection, electromagnetic stealth, dynamic focusing, reflective array antenna, beamforming and beam scanning antenna. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of a reflective 3-bit electrically controlled programmable metasurface unit according to the present invention;
[0016] Figure 2 This is in the implementation of the present invention Figure 1 Top view;
[0017] Figure 3 This is in the implementation of the present invention Figure 1 Rear cross-sectional view;
[0018] Figure 4 This is in the implementation of the present invention Figure 1 Side view;
[0019] Figure 5 This is a graph showing the relationship between the reflection amplitude and frequency of the metasurface unit of the present invention when the capacitance value is changed;
[0020] Figure 6 This is a graph showing the relationship between the reflection phase and frequency of the metasurface unit of the present invention when the capacitance value is changed;
[0021] Figure 7 This is a schematic diagram of the metasurface array structure of the present invention;
[0022] Figure 8 This is a simulation result of the continuous normalized electric field intensity distribution when a 5 GHz y-polarized electromagnetic wave is incident perpendicularly on the metasurface of this invention, and the focal point moves dynamically along a " / " trajectory on the z = 150 mm plane. Figure 8 The electric field intensity distribution on the plane z = 150 mm when the reflected electromagnetic waves are focused at points (-100, 100, 150), (0, 0, 150), and (100, 100, 150). Detailed Implementation
[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0024] A reflective 3-bit electrically controlled programmable metasurface unit, such as Figure 1 As shown, the surface includes, from top to bottom, a top surface patch 1, a first dielectric layer 2, an intermediate metal ground layer 3, an adhesive layer 4, a second dielectric layer 5, and a bottom feed layer 6. The top surface patch 1, the intermediate metal ground layer 3, and the bottom feed layer 6 are all metal layers. Dielectric layers are disposed between the top and intermediate layers, and between the intermediate and bottom layers. The top surface patch consists of two metal patches, with a varactor diode 14 placed between them to form a closed loop. The square metal patch on the top surface is connected to the metal ground layer via a metallized via, and the square metal patch is connected to the bottom feed layer via a metallized via. The varactor diode of each metasurface unit is independently controlled by a different bias voltage.
[0025] Each metasurface unit's varactor diode is controlled by a different bias voltage, enabling each programmable unit to adjust the reflection phase coverage up to 315°.
[0026] In this embodiment, as Figure 2As shown, the top-layer surface mount 1 consists of a rectangular metal patch 11, a square metal patch 12, and pads 13. A varactor diode 14 is connected to the rectangular metal patch 11 and the square metal patch 12 via two varactor diode pads, respectively. The outer frame width of the rectangular metal patch is represented by 'a', and the line width by 'w'. The side length of the square metal patch is represented by 'b'. The metal patches are printed on the dielectric layer surface using PCB manufacturing processes. The width of the metasurface unit is 23mm, and the radius of the metallized via is 0.15mm; the required pad spacing for the varactor diode is 0.76mm, and the pad width is 1.14mm; the outer side length of the top-layer rectangular metal patch is 21mm.
[0027] Figure 3 This is a back view of the metasurface unit. The bottom fan-shaped microstrip line has a radius of 6mm, and the DC signal line width is 0.25mm.
[0028] Figure 4 This is a side view of the metasurface unit. Both the first dielectric layer 2 and the second dielectric layer 5 are made of Rogers RO4350B material, with thicknesses of 1.524 mm and 0.254 mm, respectively. The Rogers RO4350B dielectric layer has a relative permittivity of 3.48 and a loss angle of 0.0037. The adhesive layer is made of Rogers RO4450F material, with a relative permittivity of 3.7, a loss angle of 0.004, and a thickness of 0.196 mm.
[0029] By changing the bias voltage of the varactor diode, the resonant frequency of the metasurface shifts to a higher frequency when the capacitance of the varactor diode decreases, thereby achieving the effect of phase modulation. Analysis revealed that increasing the linewidth w of the top-layer square frame of the metasurface unit from 0.4 mm to 1.2 mm shifts the resonant frequency to a higher frequency. Increasing the side length b of the top-layer square patch of the metasurface unit from 8 mm to 13 mm shifts the resonant frequency to a lower frequency. Taking all factors into consideration, the embodiment of this invention uses a top-layer metal frame linewidth of 1 mm and a top-layer square patch side length of 11 mm.
[0030] The varactor diodes in the metasurface array of this unit are model MGV125-08-0805, and their capacitance is controlled by applying different bias voltages. The capacitance value of the varactor diode can decrease as the voltage increases, with a capacitance range of 0.11pF - 0.43pF.
[0031] Figure 5 and Figure 6These are curves showing the frequency variation of the reflection amplitude and phase of the metasurface unit. The results indicate that, because the varactor diode is placed parallel to the y-axis, changes in its capacitance only affect the unit's electromagnetic response when y-polarized electromagnetic waves are incident, and are independent of the response when x-polarized electromagnetic waves are incident. When the y-polarized wave is incident perpendicularly, the unit achieves a phase change of up to 315° at 5 GHz as the varactor diode capacitance changes from 0.11 pF to 0.43 pF, demonstrating good phase tuning capability. Therefore, this programmable unit can dynamically switch the varactor diode capacitance to implement eight codes—"000", "001", "010", "011", "100", "101", "110", and "111"—in a 3-bit digitally encoded metasurface.
[0032] To verify that the incident plane wave on this metasurface can achieve dynamic control, a specific example is used to illustrate this. Figure 7 It is a 20*20 metasurface array with a planar size of 460×460mm. 2 .
[0033] Figure 8 This is the normalized electric field intensity distribution on the z = 150 mm plane when a 5 GHz y-polarized plane wave is incident. By switching the bias voltage distribution applied to the varactor diode, the electromagnetic wave is focused at the focal point, and dynamic focusing is achieved on the plane. Therefore, the proposed programmable metasurface has the ability to dynamically control electromagnetic waves.
Claims
1. A reflective 3-bit electrically controlled programmable metasurface structure, characterized in that, It comprises multiple periodically arranged metasurface units, each metasurface unit including: The top layer consists of two metal patches, a square metal patch and a square metal patch, with a varactor diode loaded between the two metal patches to form a closed loop for interacting with the incident electromagnetic wave and generating reflection. The first dielectric layer is located between the top patch and the intermediate metal ground; The intermediate metal ground is a continuous metal layer located between the first dielectric layer and the adhesive layer. The square metal patch is connected to the intermediate metal ground through a first metallized via. An adhesive layer is located between the intermediate metal ground and the second dielectric layer; The second dielectric layer, located between the adhesive layer and the bottom feed layer, is used to isolate the intermediate metal ground and the bottom feed layer, ensuring independent modulation of electromagnetic waves. The bottom feed layer is a metal layer located below the second dielectric layer. The square metal patch is connected to the bottom feed layer through the second metallized via to provide a bias voltage for the varactor diode, thereby controlling its capacitance value. The first metallized via between the square metal patch and the middle metal ground, and the second metallized via between the square metal patch and the bottom feed layer, form independent DC grounding and feed paths. Each metasurface unit's varactor diode is controlled by a different bias voltage, enabling each programmable unit to adjust the reflection phase to cover 300°~325°. The top layer patch includes a square metal patch and a square frame metal patch surrounding the square metal patch, and the square metal patch and the square frame metal patch are connected by the varactor diode.
2. The reflective 3-bit electrically controlled programmable metasurface structure according to claim 1, characterized in that: The width of the metasurface unit is 23 mm, and the radius of the metallized via is 0.15 mm; the required varactor diode has a pad spacing of 0.76 mm and a pad width of 1.14 mm.
3. The reflective 3-bit electrically controlled programmable metasurface structure according to claim 2, characterized in that: The two ends of the varactor diode are connected to the square metal patch and the square metal patch respectively via solder pads.
4. A reflective 3-bit electrically controlled programmable metasurface structure according to claim 2 or 3, characterized in that: The square metal patch has a side length of 11mm, the outer side length of the square metal patch is 21mm, and the line width is 1mm; the bottom fan-shaped microstrip line has a radius of 6mm, and the DC signal line width is 0.25mm.
5. The reflective 3-bit electrically controlled programmable metasurface structure according to claim 1, characterized in that: Both the first dielectric layer and the second dielectric layer are made of Rogers RO4350B material, and the thicknesses of the first dielectric layer and the second dielectric layer are set to 1.524 mm and 0.254 mm, respectively.
6. The reflective 3-bit electrically controlled programmable metasurface structure according to claim 5, characterized in that: The Rogers RO4350B dielectric layer has a relative permittivity of 3.48 and a loss angle of 0.0037; the adhesive layer uses Rogers RO4450F material, with a relative permittivity of 3.7, a loss angle of 0.004, and a thickness of 0.196 mm.
7. The reflective 3-bit electrically controlled programmable metasurface structure according to claim 1, characterized in that: The varactor diode of each metasurface unit is independently controlled by a different bias voltage, and the model of the varactor diode is MGV125-08-0805.