Broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotating surface

Abstract

The invention discloses a broadband 1-bit reconfigurable transmission array antenna unit based on a polarization rotating metasurface. The broadband 1-bit reconfigurable transmission array antenna unit comprises a top layer metal grating, a middle layer metal covering face, a lower layer metal covering face and a bottom layer metal covering face. The middle-layer metal covering surface comprises a PIN diode, a split circular ring, a first metal bias line and a second metal bias line; the split circular ring is composed of two sections of circular arcs, the number of the PIN diodes is two, the PIN diodes are connected between the two sections of circular arcs to form a complete circle, and the first metal bias line and the second metal bias line are connected to the split circular ring and serve as a direct current input end and a grounding end respectively; the lower-layer metal covering surface comprises a metal grating and a first metal column, and the first metal column connects the metal grating with the second metal bias line; the underlying metal cladding includes a second metal pillar and a metal bias line, the second metal pillar connecting the metal bias line with the metal first bias line. The invention has the advantages of broadband, high efficiency and reconfigurable phase, and can be used for a broadband wave beam electric scanning transmission array.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and further relates to a broadband 1-bit reconfigurable transmission array antenna unit based on a polarization rotation surface in the field of electromagnetic field and microwave technology. Background Art

[0002] Metasurface is a man-made two-dimensional planar structure that has attracted considerable attention due to its ability to achieve many unique functions. It is usually composed of periodic or non-periodic arrangements of metal unit structures and has unique electromagnetic properties that are not possessed by natural materials. For example, it can change the polarization direction, phase, and propagation mode of transmitted or reflected electromagnetic waves. Different types of metasurfaces have different modulation effects on electromagnetic waves. Currently, there are mainly frequency selective surfaces, artificial magnetic conductors, polarization conversion surfaces, phase gradient surfaces, etc. In recent years, more and more metasurfaces have been used in antenna design. By loading suitable active devices such as EMES, PINs, Varactors, etc., the state of the active devices is regulated to change the current distribution of the electromagnetic radiator and the current flow direction to change its radiation characteristics.

[0003] Hunan University proposed a polarization rotation unit and a beam reconfigurable array antenna in its patent application "A Polarization Rotation Unit and Beam Reconfigurable Array Antenna" (application number: CN202310537148.8, publication number: CN116598793A). The reconfigurable array antenna unit is provided with a patch layer, a dielectric layer and a control layer from top to bottom. The upper surface of the dielectric layer is provided with a patch layer, which is surrounded by a square patch and four rectangular patches of different sizes. The square patch is connected to each rectangular patch by a diode. The middle layer of the dielectric layer is covered with a metal reflector, and the lower surface is provided with a control layer, including a DC line and a fan-shaped structure. The advantage of this method is that it realizes polarization rotation and state reconfiguration, but its disadvantage is that the polarization conversion loss is large; the working bandwidth is narrow.

[0004] Chongqing University of Posts and Telecommunications proposed a beam reconfigurable slot array antenna based on loaded PIN diodes in its patent document "A beam reconfigurable slot array antenna based on loaded PIN diodes" (application number: CN202210277488.7, publication number: CN114628918A). The antenna consists of a first metal layer, a dielectric substrate, and a second metal layer from top to bottom. Eight identical rectangular radiation slots are set on the surface of the first metal layer, and each radiation slot is symmetrically distributed on both sides of the midline of the wide side of the first metal layer. A PIN diode is loaded at the center of each radiation slot to control the state of the radiation slot. By setting the eight PIN diodes in the on or off state respectively, different radiation beams can be obtained, and the beam scanning range is -56° to +56°. The present invention has the advantages of wide beam coverage and high flexibility. However, its disadvantages are that the insertion loss is large and the operating frequency band is also narrow.

[0005] Yu Hang et al. proposed a reconfigurable transmission unit in their paper “A Novel Wideband and High-Efficiency Electronically Scanning Transmitarray Using Transmission MetasurfacePolarizer”. The unit consists of a reconfigurable anisotropic metal resonator, and by controlling the ON or OFF state of two PIN diodes integrated on the anisotropic metal resonator layer, the conversion of two phase states is finally achieved. Its advantage is that by controlling the switches of each unit, the array composed of them can digitally realize two-dimensional (2-D) beam steering and multi-beam mode switching. The disadvantage is that the bandwidth is narrow. Summary of the invention

[0006] The purpose of the present invention is to address the shortcomings of the prior art and solve the problem of narrow bandwidth and low efficiency in the field of wide-angle scanning reconfigurable transmission arrays. A broadband 1-bit reconfigurable transmission array antenna unit based on a polarization rotation surface is proposed, aiming to solve the problem of achieving wide-angle scanning of the transmission array in a wide frequency band by adjusting the working state of the array unit.

[0007] The specific idea of ​​realizing the purpose of the present invention is: the current direction is controlled by turning on and off two PIN diodes, and then the phase quantization is realized by the polarization rotation surface, and the phase mutation characteristics of the two ring structures in different states are integrated by the PIN diode, so as to realize the 1-bit transmission of the polarization conversion of electromagnetic waves in a wide band. When the two PIN diodes are in the ON / OFF state, in the frequency band of 8.6 GHz to 11.8 GHz, according to the y-polarized wave incident on the polarization rotation surface, the induced current generated by the split ring according to the vector synthesis principle is mainly along the ±45° direction, which provides x and y polarization components, and the y-direction grating allows the newly generated x-polarization component to pass through, while blocking the forward scattering of the y-polarization component. For backward scattering, the x-direction grating reflects the x-polarization component and allows the y-polarization component to pass through. By adjusting the thickness of the substrate, the polarization conversion is enhanced by constructive interference, and the reflection loss is reduced by destructive interference. Therefore, in the transmission mode, the y-polarized incident wave can be effectively converted into orthogonal polarization. When the two PIN diodes are in the OFF / ON state, in the frequency band of 8.6GHz to 11.8GHz, according to the y-polarized wave incident on the polarization rotation surface, the induced current generated by the split ring according to the vector synthesis principle is mainly along the ±135° direction. In the two cases, the current distribution direction in the x-direction is opposite, indicating that a 180° phase difference can be generated.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A broadband 1-bit reconfigurable transmission array antenna unit based on a polarization rotation metasurface, characterized in that it comprises, from top to bottom, a top metal grating, a first dielectric substrate, an air layer, a middle metal coating, a second dielectric substrate, a lower metal coating, a third dielectric substrate and a bottom metal coating;

[0010] The middle metal covering includes a PIN diode, a split ring, a metal first bias line and a metal second bias line; the split ring is composed of two arcs, there are two PIN diodes, connected between the two arcs to form a complete circle, the metal first bias line and the metal second bias line are connected to the split ring, and serve as a DC input terminal and a ground terminal respectively;

[0011] The lower metal cladding includes a metal grating and a first metal column, and the first metal column passes through the second dielectric substrate to connect the metal grating with the metal second bias line;

[0012] The bottom metal covering includes a second metal column and a metal bias line. The second metal column passes through the second dielectric substrate and the third dielectric substrate to connect the metal bias line with the metal first bias line.

[0013] In one embodiment, the arc length ratio of the two end arcs of the split ring is 1:3, so that the induced current generated by the split ring is mainly along the 45° and 135° directions, providing x and y polarization components. The y-direction grating allows the newly generated x-polarization component to pass through, while blocking the forward scattering of the y-polarization component. For backward scattering, the x-direction grating reflects the x-polarization component and allows the y-polarization component to pass through.

[0014] In one embodiment, when the PIN diode is turned on, it is equivalent to a series connection of a resistor and an inductor; when it is turned off, it is equivalent to a series connection of a resistor and a capacitor; one of the two PIN diodes is selected to be turned on and the other is turned off, corresponding to unit state 0, and the reverse setting corresponds to unit state 1, so that when the unit states are different, the surface current directions in the x-direction are opposite to each other, resulting in a 180° phase difference.

[0015] In one embodiment, the metal first bias line and the metal second bias line are both located inside the split ring, the metal first bias line is connected to the midpoint of the shorter of the two arcs to control the working mode of the PIN diode; the metal second bias line is connected to the midpoint of the longer of the two arcs.

[0016] In one embodiment, the metal first bias line and the metal second bias line pass direct current and block alternating current through high impedance lines and winding equivalent inductance.

[0017] In one embodiment, the middle metal cladding further includes two metal branches, which are connected to the split ring and located inside the split ring and are symmetrically distributed on both sides of the metal second bias line.

[0018] In one embodiment, the metal branches are distributed radially along the split ring, respectively opposite to a PIN diode, and located on the diagonal line of the middle metal covering, thereby enhancing the induced current generated by the split ring, broadening the working bandwidth of the transmission performance in the two unit states, and improving the transmission amplitude.

[0019] In one embodiment, the top metal grating is composed of metal single strips evenly spaced, the direction of the metal single strips is perpendicular to the direction of the metal grating, the width of the metal single strips is 0.9 mm, the width of the single metal grating is 0.9 mm, the thickness of the first dielectric substrate, the second dielectric substrate and the third dielectric substrate are 0.5 mm, 2 mm and 0.2 mm respectively, the thickness of the air layer is 1 mm, the width of the first metal bias line and the second metal bias line are both 0.1 mm, the radius of the first metal column is 0.15 mm, the height is 2 mm, the radius of the second metal column is 0.15 mm, the height is 2.2 mm, and the width of the metal bias line is 0.1 mm; the center of the split ring is located at the center of the unit, the radius of the inner ring is 6 mm, the width is 0.3 mm, the opening width, that is, the spacing between the two arcs, is 0.2 mm, and the distance between the metal branches and the center is 0.95 mm.

[0020] In one embodiment, when different voltages are applied to the metal bias line, the PIN diode will present different working states, which can generate opposite induced currents in the split ring and produce a 180° phase difference, thereby achieving 1-bit state reconfiguration.

[0021] In one embodiment, the reconfigurable transmission units are organized into a reconfigurable transmission array, the metal gratings of each unit are interconnected, and the grounding of all the reconfigurable units is achieved by grounding the metal gratings at the outer edge of the reconfigurable transmission array; the metal bias lines of each unit are connected to one side of the array in groups of 8 units, and the operating mode of each unit is controlled by controlling the voltage of the feed line at the outer edge of the reconfigurable transmission array.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] First, since the present invention designs a reconfigurable transmission array antenna unit based on a polarization rotation surface, the polarization conversion is enhanced according to the constructive interference theory, and the reflection loss is reduced according to the destructive interference theory, so that the transmission efficiency is extremely high while the transmission unit maintains a phase difference of 180°.

[0024] Second, since the present invention loads metal branches on the middle-layer split ring, the induced current in the 45° and 135° directions is enhanced, so that both working states have extremely high polarization conversion efficiency and a wider frequency band, overcoming the problem of difficulty in widening the bandwidth of the polarization converter, so that the present invention has the advantage of effectively widening the bandwidth while maintaining the polarization conversion efficiency.

[0025] Third, since the present invention loads a high impedance line on the bias line, the mutual influence between the AC current and the DC current is reduced, which affects the working state control of the metasurface, so that the present invention has the advantage of high stability of the incident working state of electromagnetic waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0027] Figure 2 It is a top view of the middle metal cladding of the present invention.

[0028] Figure 3 It is a top view of the lower metal cladding of the present invention.

[0029] Figure 4 It is a top view of the bottom metal covering of the present invention.

[0030] Figure 5 It is a schematic diagram of the structural dimensions of the middle layer metal cladding of the present invention.

[0031] Figure 6 It is a schematic diagram of the structural dimensions of the lower metal cladding of the present invention.

[0032] Figure 7 It is a schematic diagram of the structural dimensions of the bottom metal covering of the present invention.

[0033] Figure 8 It is a curve diagram of reflection amplitude and transmission amplitude parameters under two states in the simulation experiment of the present invention.

[0034] Fig. 9 It is a curve diagram of the transmission phase parameter and the phase difference under two states in the simulation experiment of the present invention.

[0035] Fig.10 It is a curve diagram of the transmission amplitude and phase parameters under the condition of oblique incidence of the unit in the simulation experiment of the present invention.

[0036] Fig.11 It is a curve diagram of reflection amplitude and transmission amplitude parameters when a bias line is loaded in the simulation experiment of the present invention.

[0037] Fig.12 It is a schematic diagram of the model after the units are arranged in the simulation experiment of the present invention.

[0038] Fig.13 It is a schematic diagram of dividing the bias lines into two groups in the model after the units are arranged in the simulation experiment of the present invention.

[0039] Fig.14 It is the model E-plane beam scanning pattern after the units are arranged in the simulation experiment of the present invention.

[0040] Fig.15 It is the model H-surface beam scanning pattern after the units are arranged in the simulation experiment of the present invention.

[0041] Fig.16It is the gain curve and aperture efficiency obtained by arranging the units in the simulation experiment of the present invention.

[0042] In the figure: 1. top metal grating; 2. first dielectric substrate; 3. air layer; 4. middle metal covering; 5. second dielectric substrate; 6. lower metal covering; 7. third dielectric substrate; 8. bottom metal covering; 41. PIN diode; 42. split ring; 43. metal first bias line; 44. metal branch; 45. metal second bias line; 61. metal grating; 62. first metal column; 81. second metal column; 82. metal bias line. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0044] Reference Figure 1 , the overall structure of the reconfigurable transmission array antenna unit of the present invention is further described in detail.

[0045] From top to bottom, the present invention comprises an eight-layer structure of a top metal grating 1, a first dielectric substrate 2, an air layer 3, a middle metal covering 4, a second dielectric substrate 5, a lower metal covering 6, a third dielectric substrate 7, and a bottom metal covering 8.

[0046] The top metal grating 1 is located on the upper side of the first dielectric substrate 2, the air layer 3 is located between the first dielectric substrate 2 and the second dielectric substrate 5, the middle metal cladding 4 and the lower metal cladding 6 are located on the upper and lower sides of the second dielectric substrate 5. The bottom metal cladding 8 is located on the lower side of the third dielectric substrate, the middle metal cladding 4 and the lower metal cladding 6 are connected by metal columns embedded in the second dielectric substrate 5, and the middle metal cladding 4 and the bottom metal cladding 8 are connected by metal columns embedded in the second dielectric substrate 5 and the third dielectric substrate 7.

[0047] For example, in the present invention, the material of the first dielectric substrate is F4B, and the relative dielectric constant ε r =3.5, thickness is 0.5mm, thickness of air layer 3 is 1mm, material of second dielectric substrate is F4B, relative dielectric constant ε r =3.5, thickness is 2mm, the material of the third dielectric substrate is F4B, relative dielectric constant ε r =3.5, thickness is 0.2mm.

[0048] Reference Figure 2 , Figure 3 and Figure 4 , the overall structure of the metal cladding of the present invention is further described in detail.

[0049] like Figure 2As shown, the middle metal covering 4 in the present invention includes a PIN diode 41, a split ring 42, a metal first bias line 43 and a metal second bias line 45. The split ring 42 is composed of two arc segments, so that the induced current generated by the split ring 42 is in two directions. There are two PIN diodes 41, which are connected between the two arc segments to form a complete circle. The metal first bias line 43 and the metal second bias line 45 are connected to the split ring 42. The metal first bias line 43 serves as a DC input terminal to control the working mode of the PIN diode 41, and the metal second bias line 45 serves as a ground terminal. The metal first bias line 43 and the metal second bias line 45 are high-impedance lines that can isolate alternating current and ensure that the performance of the reconfigurable transmission array antenna unit is not affected without affecting the DC feeding.

[0050] Furthermore, the arc length ratio of the two end arcs of the split ring 42 is 1:3, so that the induced current generated by the split ring 42 is mainly along the 45° and 135° directions, which provides x and y polarization components. The y-direction grating allows the newly generated x-polarization component to pass through, while blocking the forward scattering of the y-polarization component. For backward scattering, the x-direction grating reflects the x-polarization component and allows the y-polarization component to pass through.

[0051] Furthermore, the two PIN diodes 41 in this embodiment are both MACOM-MADP-000907-14020W diodes manufactured by MACOM. When the left PIN diode is turned on (ON) and the right PIN diode is turned off (OFF), the cell state is 0; when the left PIN diode is OFF and the right PIN diode is turned on, the cell state is 1. When the PIN diode 41 is turned on, it can be equivalent to a 7.8 resistor and a 30pH inductor in series; when the PIN diode 41 is turned off, it can be equivalent to a 25fF resistor and a 30pF capacitor in series. By using two PIN diodes 41, the surface current in the x direction can be opposite when the cell state is different, resulting in a 180° phase difference.

[0052] Furthermore, in this embodiment, the width of the first metal bias line 43 is 0.1 mm, and the inside of the split ring 42 is connected to the midpoint of the shorter of the two arcs. The width of the second metal bias line 45 is 0.1 mm, and it is located inside the split ring 42, and is connected to the midpoint of the longer of the two arcs. Thus, the first metal bias line 43 and the second metal bias line 45 are arranged opposite to each other. The high impedance line and the winding equivalent inductance can be used to pass the direct current and block the alternating current, thereby reducing the influence of the induced current generated by the electromagnetic wave on the surface of the polarization converter on the direct current input.

[0053] Furthermore, the middle metal cladding 4 of the present embodiment further includes two metal branches 44, which are connected to the split ring 42 and located inside it, and are symmetrically distributed on both sides of the metal second bias line 45. The metal branches 44 can be distributed along the radial direction of the split ring 42, respectively opposite to a PIN diode 41, so as to enhance the 45° and 135° induced currents generated by the split ring 42, broaden the working bandwidth of the transmission performance in the two unit states, and improve the transmission amplitude. When the center of the middle metal cladding 4 overlaps with the projection of the unit center, the two metal branches 44 are located on the diagonal line of the middle metal cladding 4.

[0054] like Figure 3 As shown, the lower metal cladding 6 in the present invention includes a metal grating 61 and a first metal column 62. The first metal column 62 is embedded in the second dielectric substrate 5, has a radius of 0.15 mm, and is 2 mm high, and connects the metal grating 61 to the metal second bias line 45 of the middle metal cladding 4. The metal grating 61 is orthogonal to the top metal grating 1.

[0055] When multiple reconfigurable transmission array antenna units of the present invention form a reconfigurable transmission array, the metal gratings 61 of each reconfigurable unit will be connected to each other, and finally all reconfigurable units can be grounded by grounding the metal gratings 61 at the outer edge of the reconfigurable transmission array.

[0056] like Figure 4 As shown, the bottom metal cladding 8 in the present invention includes a second metal column 81 and a metal bias line 82. The second metal column 81 is embedded in the second dielectric substrate 5 and the third dielectric substrate 7, and has a radius of 0.15 mm and a height of 2.2 mm. The metal bias line 82 is connected to the metal first bias line 43 of the middle metal cladding 4. Through the feeding of the two bias lines, the voltages at both ends of the two PIN diodes 41 are controlled at the same time, so as to realize the switch control of the PIN diode 41. Specifically, when different voltages are applied to the metal bias line 82, the PIN diode 41 will present different working states, and can generate a 180° phase difference in the opposite induced current of the split ring 42, thereby realizing the 1-bit state reconfiguration.

[0057] When a plurality of reconfigurable transmission array antenna units of the present invention form a reconfigurable transmission array, by connecting the metal bias line 82 on the metal coating 8 on the bottom surface of each unit to one side of the array in groups of 8 units, the operating mode of each unit can be controlled by controlling the voltage of the feed line at the outer edge of the reconfigurable transmission array.

[0058] Reference Figure 5 , Figure 6 and Figure 7 , the size of the reconfigurable transmission unit structure of the present invention is further described in detail.

[0059] like Figure 5 As shown, the cross section of the reconfigurable transmission array antenna unit of the present invention is a square with a side length of P, P = 8.5mm. The split ring 42 takes the center of the square as the center, the inner ring radius is r1, the width is g1, and the width of the two openings is w1, where r1 = 6mm, g1 = 0.3mm, w1 = 0.2mm; the opening of the split ring 42 is connected by two PIN diodes 42. The width of the first metal bias line 43 is w2, the overall width of the first metal bias line 43 is w3, and the distance from the inner edge of the shorter arc of the split ring 42 is l1. The overall width of the second metal bias line 45 is w4, and the distance from the inner edge of the longer arc of the split ring 42 is l2, where w2 = 0.1mm, w3 = 1.5mm, l1 = 1.1mm, w4 = 1.9mm, l2 = 0.3mm. The distance from the center of the metal branch 44 is r2, where r2 = 0.95mm.

[0060] like Figure 6 As shown, the single metal grating 61 of the reconfigurable transmission array antenna unit of the present invention is of sub-wavelength size, with a width of w6, the interval between adjacent metal gratings 61 is w5, the radius of the circular hole in the metal grating 61 is r3, the radius of the first metal column 62 is r4, and the distance between the circular hole and the column is l3, wherein w6=0.9mm, w5=0.8mm, r3=0.3mm, r4=0.15mm, l3=1.4mm. Correspondingly, the top metal grating 1 is composed of metal single strips arranged evenly at intervals, the direction of the metal single strips is perpendicular to the direction of the metal grating 61, the metal single strips have sub-wavelength size, the width is 0.9mm, and the interval between adjacent metal single strips is 0.8mm. In a specific embodiment, the top metal grating 1 is composed of 5 equally spaced metal single strips parallel to the y direction. The lower metal covering 6 is composed of 5 equally spaced metal gratings 61 parallel to the x direction.

[0061] like Figure 7 As shown, the width of the bottom metal bias line 82 of the reconfigurable transmission array antenna unit of the present invention is w7, where w7=0.1 mm.

[0062] The thickness of the first dielectric substrate 2 of the present invention is h1, h1=0.5mm, the thickness of the air layer 3 is h2, h2=1mm, the thickness of the second dielectric substrate 5 is h3, h3=2mm, and the thickness of the third dielectric substrate 7 is h4, h4=0.2mm.

[0063] According to the above structure, the present invention has the advantages of broadband, high efficiency and phase reconfiguration, and can be used in the 8.6-11.8GHz band under different working conditions. Within the working band, it can realize the function of rotating the linear polarization state to its orthogonal polarization state with two different phases, and is suitable for high-gain transmission array antenna beam electronic control scanning.

[0064] The following is a further description of the technical effects of the present invention in combination with simulation experiments:

[0065] The commercial simulation software HFSS2022R1 is used to simulate the present invention. When the unit is in state 0 and state 1, the unit converts the vertically incident x-polarized wave into the y-polarized transmission wave, and the reflection amplitude curve for the vertically incident x-polarized wave is as follows: Figure 8 shown. Figure 8 The horizontal axis is the frequency value in GHz, and the vertical axis is the transmission and reflection amplitude in dB. Figure 8 The solid circular line in the figure is the transmission amplitude curve of state 0, and the solid inverted triangle line is the transmission amplitude curve of state 1; the dashed square line is the reflection amplitude curve of state 0, and the dashed triangle line is the reflection amplitude curve of state 1. The transmission amplitude of the two states is greater than -1dB in the range of 8.5GHz to 11.8GHz, and the transmission amplitude is the highest at 11GHz, which can reach about -0.45dB. The reflection amplitude is less than -10dB in the range of 8.5GHz to 11.8GHz, and the reflection amplitude is the lowest at 11.2GHz, and the two states can reach about -16dB.

[0066] The transmission phase performance curves of the unit for the vertically incident x-polarized wave obtained by modeling and simulating the present invention using the commercial simulation software HFSS2022R1 are as follows: Fig. 9 shown. Fig. 9 The horizontal axis is the frequency value, the unit is GHz, and the vertical axis is the transmission phase, the unit is deg. Fig. 9 The square solid line in the figure is the transmission phase curve of state 0, the circular solid line is the transmission phase curve of state 1, and the triangular dotted line is the phase difference curve between state 0 and state 1. The transmission phases of the two states have a stable phase difference of 180° within 7 GHz to 13 GHz.

[0067] The transmission amplitude and transmission phase curves of the unit for oblique incident x-polarized waves obtained by modeling and simulating the present invention using commercial simulation software HFSS2022R1 are as follows: Fig.10 shown. Fig.10 The horizontal axis is the frequency value in GHz, the vertical axis on the left is the transmission amplitude in dB, and the vertical axis on the right is the transmission phase in deg. Fig.10The square solid line is the transmission amplitude curve at oblique incidence of 0°, the circular solid line is the transmission amplitude curve at oblique incidence of 10°, the triangular solid line is the transmission amplitude curve at oblique incidence of 20°, and the inverted triangular solid line is the transmission amplitude curve at oblique incidence of 30°. When the incident angle changes from 0° to 30°, the transmission amplitude and phase only change slightly.

[0068] The transmission amplitude curve of the unit obtained by modeling and simulating the present invention using the commercial simulation software HFSS2022R1 for converting the vertically incident x-polarized wave into the y-polarized transmission wave after loading the bias line and the reflection amplitude for the vertically incident x-polarized wave are as follows: Fig.11 shown. Fig.11 The horizontal axis is the frequency value in GHz, and the vertical axis is the transmission and reflection amplitude in dB. Fig.11 The square solid line is the transmission amplitude curve after loading the bias line, the triangle solid line is the transmission amplitude curve without loading the bias line, the circle solid line is the reflection amplitude curve after loading the bias line, and the inverted triangle solid line is the transmission amplitude curve without loading the bias line. After loading the bias line, the transmission amplitude of the unit is greater than -1dB in the range of 8.6GHz to 11.9GHz, wherein the transmission amplitude is the highest at 11GHz, which can reach about -0.4dB. The reflection amplitude is less than -10dB in the range of 8.6GHz to 11.9GHz, wherein the reflection amplitude at 11.2GHz is the lowest, and the two states can reach about -22.5dB. The relative bandwidth of the 1dB transmission amplitude of the present invention is 32.2%. Therefore, by controlling the on-off of the PIN diode, the transmission phase of the present invention can be flexibly adjusted, so that the present invention has a 1-bit reconfigurable function.

[0069] The reconfigurable projection units based on the polarization rotation surface of the present invention are arrayed in the form of 16×16, with the horn antenna as the feed source. The array surface phase distribution encoding is realized by adjusting the switching state of the PIN diode of the array unit to achieve wide-angle beam scanning.

[0070] The model diagram and the E-surface and H-surface beam scanning diagrams obtained by using the commercial simulation software HFSS2022R1 for the unit arrangement of the present invention are as follows: Fig.12 , Fig.13 , Fig.14 , Fig.15 and Fig.16 As shown. Combined Fig.12 The arrangement of the units of the present invention is further described. The array is composed of 16×16 reconfigurable units, and the F / D is 0.7. In order to facilitate the design of the external bias line, the array bias lines are divided into two groups, such as Fig.13, where each group is divided into eight groups, each group is shown in the box, and bias voltage is applied to 8 units. The commercial simulation software HFSS2022R1 is used to simulate the present invention, and the E-plane and H-plane beam scanning direction diagrams obtained by the present invention according to the array phase distribution coding control are shown as follows: Fig.14 and Fig.15 As shown. Through analysis, it is known that the main lobe angle in the E plane and the H plane has a good consistency with the expected scanning angle of 0° to 50°, and the maximum scanning gain loss measured on the E plane and the H plane is 2.9dB and 3.4dB respectively. The gain curve and aperture efficiency obtained by the arrangement of the array according to the transmission array phase arrangement control by the present invention are shown in the following figure. Fig.16 The results show that the maximum gain of the reconfigurable array at 10.8 GHz is 20.19 dBi, the aperture efficiency is 34.8%, the 3 dB gain bandwidth is 9.13 GHz to 11.83 GHz, and the relative bandwidth is 25.8%. Therefore, the proposed array composed of reconfigurable units has good wide-angle beam scanning capability.

[0071] The above simulation results show that, compared with the prior art, the present invention can effectively widen the bandwidth while maintaining an extremely high transmission amplitude. By controlling the on and off of the PIN diode, the working state of the present invention can be changed at will, and a 1-bit adjustable phase capability can be obtained, solving the problem of narrow bandwidth and low efficiency in the field of wide-angle scanning reconfigurable transmission arrays. In addition, by adjusting the switching state of the array unit PIN diode to achieve array phase distribution encoding, the reconfigurable array can perform beam scanning within the range of 50° on the E and H planes, thereby realizing the wide-angle scanning characteristics of the transmission array in a wide frequency band.

Claims

1. A broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface, It is characterized in that It comprises, from top to bottom, a top metal grating (1), a first dielectric substrate (2), an air layer (3), a middle metal coating (4), a second dielectric substrate (5), a lower metal coating (6), a third dielectric substrate (7) and a bottom metal coating (8); The middle metal covering (4) comprises a PIN diode (41), a split ring (42), a metal first bias line (43) and a metal second bias line (45); the split ring (42) is composed of two arc segments, the PIN diode (41) has two segments and is connected between the two arc segments to form a complete circle, the metal first bias line (43) and the metal second bias line (45) are connected to the split ring (42) and serve as a direct current input terminal and a ground terminal respectively; The lower metal coating (6) comprises a metal grating (61) and a first metal column (62), wherein the first metal column (62) passes through the second dielectric substrate (5) to connect the metal grating (61) to a metal second bias line (45); The bottom metal coating (8) comprises a second metal column (81) and a metal bias line (82); the second metal column (81) passes through the second dielectric substrate (5) and the third dielectric substrate (7) to connect the metal bias line (82) with the metal first bias line (43).

2. According to the broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface according to claim 1, It is characterized in that The arc length ratio of the two end arcs of the split circular ring (42) is 1:3, so that the induced current generated by the split circular ring (42) is mainly along the 45° and 135° directions, providing x and y polarization components, and the y direction grating allows the newly generated x polarization component to pass through while blocking the forward scattering of the y polarization component. For backward scattering, the x direction grating reflects the x polarization component and allows the y polarization component to pass through.

3. According to the broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface of claim 1, It is characterized in that When the PIN diode (41) is turned on, it is equivalent to a series connection of a resistor and an inductor; when it is turned off, it is equivalent to a series connection of a resistor and a capacitor; one of the two PIN diodes (41) is turned on and the other is turned off, corresponding to unit state 0, and the reverse setting corresponds to unit state 1, so that when the unit states are different, the surface current directions in the x direction are opposite to each other, resulting in a 180° phase difference.

4. According to the broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface of claim 1, It is characterized in that The first metal bias line (43) and the second metal bias line (45) are both located inside the split ring (42); the first metal bias line (43) is connected to the midpoint of the shorter of the two arcs to control the working mode of the PIN diode (41); and the second metal bias line (45) is connected to the midpoint of the longer of the two arcs.

5. According to the broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface of claim 1, It is characterized in that The metal first bias line (43) and the metal second bias line (45) pass direct current and block alternating current through high impedance lines and winding equivalent inductance.

6. The broadband 1-bit reconfigurable transmission array antenna unit based on the polarization rotation metasurface according to any one of claims 1 to 5, It is characterized in that The middle metal covering (4) further comprises two metal branches (44), the two metal branches (44) are connected to the split ring (42) and are located inside the split ring (42), and are symmetrically distributed on both sides of the metal second bias line (45).

7. According to claim 6, the broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface, It is characterized in that The metal branches (44) are distributed along the radial direction of the split ring (42), respectively facing a PIN diode (41), and located on the diagonal line of the middle metal cover (4), so as to enhance the induced current generated by the split ring (42), broaden the working bandwidth of the transmission performance in the two unit states, and simultaneously improve the transmission amplitude.

8. According to claim 6, the broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface, It is characterized in that The top metal grating (1) is composed of metal single strips arranged evenly at intervals, the direction of the metal single strips is perpendicular to the direction of the metal grating (61), the width of the metal single strips is 0.9 mm, the width of the single metal grating (61) is 0.9 mm, the thickness of the first dielectric substrate (2), the second dielectric substrate (5) and the third dielectric substrate (7) are 0.5 mm, 2 mm and 0.2 mm respectively, the thickness of the air layer (3) is 1 mm, the metal first bias line (43) and the metal second The width of the bias line (45) is 0.1mm, the radius of the first metal column (62) is 0.15mm, the height is 2mm, the radius of the second metal column (81) is 0.15mm, the height is 2.2mm, and the width of the metal bias line (82) is 0.1mm; the center of the split ring (42) is located at the center of the unit, the inner ring radius is 6mm, the width is 0.3mm, the opening width, that is, the spacing between the two arcs, is 0.2mm, and the distance between the metal branch (44) and the center is 0.95mm.

9. According to claim 1, the broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface, It is characterized in that When different voltages are applied to the metal bias line (82), the PIN diode (41) will present different working states, and can generate opposite induced currents in the split ring (42) to produce a 180° phase difference, thereby achieving 1-bit state reconfiguration.

10. According to claim 1, the broadband 1-bit reconfigurable transmission array antenna unit based on polarization rotation metasurface, It is characterized in that The reconfigurable transmission units are combined into a reconfigurable transmission array, the metal gratings (61) of each unit are connected to each other, and the grounding of all the reconfigurable units is achieved by grounding the metal gratings (61) at the outer edge of the reconfigurable transmission array; the metal bias lines (82) of each unit are connected to one side of the array in groups of 8 units, and the operating mode of each unit is controlled by controlling the voltage of the feed line at the outer edge of the reconfigurable transmission array.

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