Transparent 2-bit programmable reflective conformal coding metasurface

Abstract

The invention discloses a light-transmitting 2bit programmable reflective conformal coding metasurface, which realizes beam scanning of a curved conformal active metasurface antenna and comprises a transparent dielectric substrate and two polyester resin layers, the dielectric substrate is clamped between the two polyester resin layers, a rectangular metal patch and a metal feeder are printed on the upper side and the lower side of the first polyester resin layer, and the rectangular metal patch and the metal feeder are printed on the upper side and the lower side of the second polyester resin layer. A variable capacitance diode is integrated on the surface metal patch, and a linear metal floor is printed on the upper side of the second polyester resin layer. The light-transmitting 2-bit programmable reflective conformal coding metasurface provided by the invention has the characteristics of high light transmittance and easy conformality, is convenient to load on the exterior of a building, an aircraft fuselage, a satellite and other parts with curved surface structures, and can also be applied to windows and other scenes requiring light transmission; the capacitance value is changed by regulating the voltage at the two ends of the variable capacitance diode integrated on the surface of the unit, so that different phase responses are obtained, the beam scanning function is achieved, and the device can be applied to a communication system of a curved surface carrier platform.

Description

Technical Field

[0001] The present invention belongs to the field of metasurface design, and in particular relates to a transparent 2-bit programmable reflective conformal coding metasurface. Background Art

[0002] A metasurface is an artificially designed and manufactured periodic or non-periodic structure array with sub-wavelength thickness. It has excellent electromagnetic wave control capabilities. By controlling the amplitude, phase and polarization of electromagnetic waves, it can achieve many functions, such as RCS reduction, vortex wave generation, invisibility cloak, holographic imaging and beam scanning.

[0003] Metasurfaces are divided into active metasurfaces and passive metasurfaces. Passive metasurfaces can form directional reflection or transmission electromagnetic waves by periodically arranging specific unit structures. However, once a passive metasurface is made, its structure is fixed and its function cannot be changed, so it is impossible to realize dynamic beam scanning function. Active metasurfaces can realize beam scanning function by dynamically regulating metasurface units through loaded active devices. Most of the existing active metasurfaces are planar structures and are not light-transmitting. They cannot realize beam scanning function in various carrier platforms with curved shapes and some specific scenes that require light transmission. Summary of the invention

[0004] The present invention proposes a light-transmitting 2-bit programmable reflective conformal coding metasurface, which can realize beam scanning of curved conformal active metasurface antenna. The metasurface is composed of periodically arranged units, the material is transparent and bendable, the transmittance can reach an average of 45%, and it can achieve conformal, which is a flexible programmable metasurface. The purpose of the present invention is to solve an existing metasurface technology problem: conformal metasurfaces cannot simultaneously achieve phase control and transparent application scenarios.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a transparent 2-bit programmable reflective conformal coding metasurface, characterized in that: the digital coding metasurface is composed of 15×27 basic units arranged periodically, and each basic unit is composed of a metal pattern layer 1, a first polyester resin (Polyethylene terephthalate, PET) layer 2, a metal feed layer 3, a first dielectric layer 4, a metal floor layer 5 and a second PET layer 6 stacked in sequence; the metal pattern layer 1 is two rectangular metal patches, and a varactor diode 7 is integrated on the patch, the metal feed layer 3 has two metal wires, and the two rectangular metal patches of the metal pattern layer 1 are connected by a metal through hole 8 to provide a bias voltage for the varactor diode integrated between the two metal patches, and the metal floor layer 5 is a linear metal floor.

[0006] The basic unit structure period is 16 mm.

[0007] The first dielectric layer 4 is made of curved polycarbonate with a thickness of 3 mm. The dielectric constant of the dielectric layer is 2.9 and the tangent loss angle is 0.007.

[0008] The two rectangular metal patches on the metal pattern layer 1 are 14 mm long, 6.55 mm wide and 0.9 mm apart; the two metal wires on the metal feeder layer 3 are 0.02 mm wide and 13 mm apart; the outer diameter of the metal through hole 8 is 0.3 mm and the inner diameter is 0.25 mm.

[0009] The two rectangular metal patches on the metal pattern layer 1 are provided with rectangular slots inside, the slots are 12 mm long and 4.55 mm wide, and the varactor diode is loaded between the two rectangular patches and provided with a metal pad of 1 mm×2 mm in size.

[0010] The thickness of the first PET layer 2 and the second PET layer 6 is 0.1 mm, the dielectric constant of the dielectric layer is 2.9, and the tangent loss angle is 0.007.

[0011] The metal pattern layer 1 , the metal feed line layer 3 and the metal floor layer 5 are all made of metal copper and are printed on the first PET layer 2 and the second PET layer 6 by FPC technology.

[0012] By applying different voltages to the metal feed line layer 3 and changing the capacitance of the varactor diode 8, the phase of the metasurface can be regulated.

[0013] The far-field pattern of the programmable metasurface unit is Its expression is:

[0014]

[0015] Among them, the direction diagram of the (m,n)th unit is f e (m,n), the reflection phase is The wave vector k = 2π / λ, λ is the wavelength, and p is the unit period. The pitch angle and azimuth angle are used to calculate the phase of each unit according to the pre-designed scanning angle. The control of the unit in the present invention is column control. The azimuth angle during beam scanning is So the unit phase expression is:

[0016] Beneficial effects: The present invention proposes a light-transmitting 2-bit programmable reflective conformal coding metasurface, and the basic unit constituting the metasurface has 2-bit phase control and light-transmitting capabilities. The present invention can achieve beam scanning of the conformal metasurface by applying different voltages to the metallized vias to obtain different phase responses; the present invention can make brackets of different shapes according to the usage scenario, and install the flexible PET layer on the transparent polycarbonate bracket, which greatly broadens the application scenarios of the metasurface; thanks to its light transmittance, it can be applied to the glass of buildings, airplanes, and light windows of satellites. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the overall schematic diagram of the metasurface array, and the bending angle of the metasurface is 162°.

[0018] Figure 2 It is a structural diagram of the basic unit.

[0019] Figure 3 a is the plan view of the metal pattern layer, Figure 3 b is the plan view of the metal feeder layer. Figure 3 c is the plan view of the metal floor layer.

[0020] Figure 4 a is the simulation result of the unit reflection amplitude when the varactor diode takes different capacitances under normal incidence of x-axis polarized plane wave. Figure 4 b is the simulation result of the unit reflection phase when the varactor diode takes different capacitances under normal incidence of x-axis polarized plane wave.

[0021] Figure 5 a is the simulation result of the unit reflection amplitude when the varactor diode takes different capacitances under the x-axis polarized plane wave with 60° oblique incidence. Figure 5 b is the simulation result of the unit reflection phase when the varactor diode takes different capacitances under 60° oblique incidence of x-axis polarized plane wave.

[0022] Figure 6 The simulation results of the metasurface at a scanning angle of 0° to 50° with a step size of 10°.

[0023] Figure numerals: 1. metal pattern layer; 2. first PET layer; 3. metal feed line layer; 4. first dielectric layer; 5. metal floor layer; 6. second PET layer; 7. varactor diode; 8. metal through hole. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0025] The light-transmitting 2-bit programmable reflective conformal coding metasurface of the present invention is composed of 15×27 basic units arranged in a periodic manner, and each basic unit is composed of a metal pattern layer 1, a first PET layer 2, a metal feed line layer 3, a first dielectric layer 4, a metal floor layer 5 and a second PET layer 6 stacked in sequence; the metal pattern layer 1 is two rectangular metal patches, and a varactor diode 7 is integrated on the patch, the metal feed line layer 3 has two metal wires, and the two rectangular metal patches of the metal pattern layer 1 are connected by a metal through hole 8 to provide a bias voltage for the varactor diode integrated between the two metal patches, and the metal floor layer 5 is a linear metal floor.

[0026] The basic unit structure period is 16 mm.

[0027] The first dielectric layer 4 is made of curved polycarbonate with a thickness of 3 mm. The dielectric constant of the dielectric layer is 2.9 and the tangent loss angle is 0.007.

[0028] like Figure 3 As shown in a, the metal pattern layer is periodically arranged on the surface, and its period P is 0.16 to 0.176 times the wavelength of the incident wave. Two rectangular metal patches on the metal pattern layer are provided with rectangular slots inside, and the varactor diode is loaded between the two rectangular patches. The two metal patches are connected to the two metal wires of the metal feed layer through metal through holes. The plan view of the metal feed layer is shown in Figure 3 The metal floor plan is shown in b. Figure 3 As shown in c, by adjusting the number and distance of metal wires, the unit can obtain a higher reflection amplitude, and finally it is decided to select 8 metal wires with a spacing of 2㎜ as the metal floor. Figure 3 The parameters in a are P=16, L1=14, L2=4.55, L3=5, W1=1, W2=2, W3=2, d=0.6, g=0.9, all in mm; Figure 3 The width of the metal wire in b and c is 0.2 mm.

[0029] The thickness of the first PET layer 2 and the second PET layer 6 is 0.1 mm, the dielectric constant of the dielectric layer is 2.9, and the tangent loss angle is 0.007.

[0030] The metal pattern layer 1 , the metal feed line layer 3 and the metal floor layer 5 are all made of metal copper and are printed on the first PET layer 2 and the second PET layer 6 by FPC technology.

[0031] By applying different voltages to the metal feed line layer 3 and changing the capacitance of the varactor diode 8, the phase of the metasurface can be regulated.

[0032] The far-field pattern of the programmable metasurface unit is Its expression is:

[0033]

[0034] Among them, the direction diagram of the (m,n)th unit is f e (m,n), the reflection phase is The wave vector k = 2π / λ, λ is the wavelength, and p is the unit period. The pitch angle and azimuth angle are used to calculate the phase of each unit according to the pre-designed scanning angle. The control of the unit in the present invention is column control. The azimuth angle during beam scanning is So the unit phase expression is:

[0035] In order to intuitively express the phase control capability of the unit under the incident electromagnetic wave of the working frequency band, the present invention obtains different phase responses by changing the capacitance of the varactor diode.

[0036] Figure 4 The simulation results of the unit reflection amplitude and phase under the condition of vertical electromagnetic wave incidence are given. The unit reflection amplitude is higher than -2dB at 3-3.3GHz, and has a good 2bit phase response at 3.15GHz. Figure 5 The simulation results of the unit reflection amplitude and phase when the electromagnetic wave is incident at an oblique angle of 60° show that the unit can still obtain a 2-bit phase response at a larger incident angle, and the reflection amplitude is still greater than -2dB.

[0037] Figure 6 The simulation results of the metasurface with a scanning angle of 0° to 50° at 3.15GHz are given, with a step size of 10°. The simulation results are basically consistent with the designed scanning angle, and the main lobe gain is at least 4.8dB higher than the secondary lobe. It can be seen that the conformal metasurface of the present invention can meet the requirements of precise beam scanning and larger-angle beam pointing.

Claims

1. A transparent 2-bit programmable reflective conformal coding metasurface, characterized by: The digital coding metasurface is composed of 15×27 basic units arranged in a periodic manner, each basic unit being composed of a metal pattern layer (1), a first polyester resin layer (i.e., a first PET layer (2), a metal feeder layer (3), a first dielectric layer (4), a metal floor layer (5), and a second PET layer (6) stacked in sequence; the metal pattern layer (1) is two rectangular metal patches, and a variable capacitance diode (7) is integrated on the rectangular metal patches; the metal feeder layer (3) has two metal wires, which are connected to the two rectangular metal patches of the metal pattern layer (1) through a metal through hole (8) to provide a bias voltage for the variable capacitance diode integrated between the two rectangular metal patches; and the metal floor layer (5) is a linear metal floor.

2. The transparent 2-bit programmable reflective conformal coding metasurface according to claim 1, characterized in that: The basic unit structure period is 16 mm.

3. The transparent 2-bit programmable reflective conformal coding metasurface according to claim 1, characterized in that: The first dielectric layer (4) is curved polycarbonate with a thickness of 3 mm. The dielectric constant of the first dielectric layer (4) is 2.9 and the tangent loss angle is 0.

007.

4. The transparent 2-bit programmable reflective conformal coding metasurface according to claim 1, characterized in that: The two rectangular metal patches on the metal pattern layer (1) are 14 mm long, 6.55 mm wide and 0.9 mm apart; the two metal wires on the metal feeder layer (3) are 0.02 mm wide and 13 mm apart; the outer diameter of the metal through hole (8) is 0.3 mm and the inner diameter is 0.25 mm.

5. The transparent 2-bit programmable reflective conformal coding metasurface according to claim 1, characterized in that: The two rectangular metal patches on the metal pattern layer (1) are provided with rectangular slots inside, the slots are 12 mm long and 4.55 mm wide, the varactor diode is loaded between the two rectangular metal patches, and a metal pad with a size of 1 mm×2 mm is provided.

6. The transparent 2-bit programmable reflective conformal coding metasurface according to claim 1, characterized in that: The thickness of the first PET layer (2) and the second PET layer (6) is 0.1 mm, the dielectric constant of the dielectric layer is 2.9, and the tangent loss angle is 0.

007.

7. The transparent 2-bit programmable reflective conformal coding metasurface according to claim 1, characterized in that: The metal pattern layer (1), the metal feeder layer (3) and the metal floor layer (5) are all made of metal copper and are printed on the first PET layer (2) and the second PET layer (6) by using FPC technology.

8. The transparent 2-bit programmable reflective conformal coding metasurface according to claim 1, characterized in that: By loading different voltages on the metal feed line layer (3), the capacitance of the variable capacitance diode (8) is changed, thereby adjusting the phase of the metasurface.

9. The transparent 2-bit programmable reflective conformal coding metasurface according to claim 1, characterized in that: The far-field pattern of the programmable metasurface unit is The expression is: Among them, the directional pattern of the (m, n)th unit is f e (m, n), the reflection phase is Wave vector k = 2π / λ, λ is the wavelength, p is the unit period; The pitch angle and azimuth angle are calculated according to the designed scanning angle. The unit is controlled by column control. The azimuth angle during beam scanning is So the unit phase expression is:

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