Electric control liquid crystal 2-bit reconfigurable folding reflective array antenna

Abstract

The invention relates to an electrically controlled liquid crystal 2-bit reconfigurable folding reflective array antenna, and belongs to the technical field of communication antennas. The antenna comprises a main reflective array, an auxiliary reflective array and a microstrip patch antenna array feed source located in the middle area of the main reflective array. Wherein a nylon column is arranged between the main reflective array and the auxiliary reflective array for supporting. The main reflective array comprises a plurality of reflective metasurface units which are periodically arranged and mutually independent; and the reflective metasurface units are used for carrying out polarization conversion and phase compensation on incident electromagnetic waves. The sub-reflection array comprises sub-reflection units which are arranged periodically and used for transmitting polarized waves which are not consistent with the feed source and reflecting the polarized waves which are consistent with the feed source. According to the invention, the aperture efficiency and the regulation and control precision of the antenna array are improved, and the advantages of low profile, easy integration and the like can be realized while high aperture efficiency and excellent two-dimensional scanning capability are maintained. In addition, a folded array structure is realized, and the problem of feed source shielding during antenna radiation is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of communication antennas and relates to a 2-bit reconfigurable folded reflective array antenna of an electrically controlled liquid crystal. Background Art

[0002] In recent years, with the rapid development of the Internet of Vehicles (IoV) and smart electric vehicles, various types of antennas have been widely used in vehicle communication and perception systems. In the early days, vehicles relied on drivers to control the entire process, and had a weak direct correlation with life safety; in today's era of autonomous driving and intelligent interconnection driven by technology, vehicles require a high degree of human-machine collaboration, and life safety is of paramount importance. This development trend requires on-board sensors to continuously monitor the environment and collect data, and to achieve data exchange and wireless communication between vehicles, vehicles and roads, and vehicles and obstacles through the Internet. However, the surge in communication links may cause data packet collisions, resulting in higher power consumption and lower network efficiency. To meet this challenge, reconfigurable beam antennas have become a preferred choice because they can direct narrow beams to specific directions, effectively reducing interference, data collision rates and delays. In addition, the tight spectrum resources and the propagation losses of high-frequency bands such as millimeter waves and terahertz make it urgent for future communication fields such as vehicle networks to have millimeter-wave antennas with high aperture efficiency and beam reconfigurability.

[0003] At present, a wealth of methods have been accumulated for the research of beam reconfigurable antennas. The most common phased array uses the phase difference between adjacent antenna units to achieve beam deflection, but such antennas are usually complex to feed and expensive, and the dense port distribution requires more RF equipment and phase shifters, resulting in rising costs. Compact reconfigurable arrays reduce costs through tight coupling, but the complex structure requires extremely high manufacturing precision and is easily affected by small errors. Radiation and impedance matching. Other low-cost solutions use PIN diodes, varactor diodes, MEMS, liquid crystals and graphene technologies to achieve beam reconstruction, but these antennas usually have low gain, so designing high-gain beam reconfigurable antennas is still challenging.

[0004] Transmission arrays or reflection arrays are common in achieving high gain and high aperture efficiency because they improve radiation performance by focusing or in-phase reflection. However, these antennas usually lack reconfigurable beam directions. In order to improve the beam reconstruction performance, some studies have tried to introduce phase control schemes in reflection or transmission arrays, but 1-bit phase quantization control is generally used. Although it is simple and easy, it will lead to a decrease in gain and aperture efficiency. The passive control devices of the 1-bit phase quantization scheme mostly use PIN diodes or RF MEMS switches, which lose about 3dB gain due to phase error, thereby significantly reducing the antenna efficiency. Relatively speaking, the 2-bit phase quantization scheme can significantly improve the phase accuracy and reduce the loss to less than 0.8dB, but it is still challenging to improve the array phase accuracy without increasing the complexity of unit design. At the same time, this part of the antenna usually has a high profile, and this type of array antenna usually uses horn feeding, which further increases the profile height and has poor integration. Therefore, designing an antenna with high gain, low profile and beam reconstruction capabilities is still a key requirement in current and future communication applications. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a 2-bit reconfigurable folded reflectarray antenna with an electrically controlled liquid crystal to reduce the profile height of the reflectarray antenna, while replacing the antenna horn with a microstrip patch antenna array for easy integration, so as to solve the problem of feed source shielding of the reflectarray antenna, improve the aperture efficiency of the antenna, and maintain good two-dimensional beam scanning performance.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A 2-bit reconfigurable folded reflector array antenna of electrically controlled liquid crystal includes a main reflector array, a sub-reflector array, and a microstrip patch antenna array feed source located in the middle area of ​​the main reflector array. A nylon column is provided between the main reflector array and the sub-reflector array for support.

[0008] The main reflector array includes a plurality of periodically arranged and mutually independent reflective metasurface units, which are used to perform polarization conversion and phase compensation on incident electromagnetic waves. The period of the unit is 6 mm (greater than half of the free space wavelength of 24 GHz). The sub-reflector array includes periodically arranged sub-reflective units, which are used to transmit polarized waves inconsistent with the feed source and reflect polarized waves consistent with the feed source.

[0009] Furthermore, the reflective metasurface unit includes a receiving / radiating layer, an upper dielectric plate, an orthogonal gap layer for polarization conversion, a liquid crystal layer for phase tuning, a phase shift layer for cooperating to complete phase tuning and polarization conversion, a lower dielectric plate and a lower floor layer stacked in sequence from top to bottom. In addition, the liquid crystal layer is also provided with a liquid crystal frame for mounting separated liquid crystals.

[0010] Furthermore, the phase shift layer includes a group of differential feed lines with curved structures and centrally symmetrical distribution. The bends of the feed lines are cut to reduce the discontinuity effect of electromagnetic wave transmission at the bends. At the same time, the feed lines are kept at a certain width to reduce the influence between each other, and the terminals of the feed lines use short-circuit junctions to reduce terminal loss and reflection.

[0011] The differential feed line is used to excite the slots of the orthogonal slot layer, making the radiation electric field more uniform and thus improving the performance of the reflective metasurface unit. The range of phase shift can be increased by the meandering distribution of the feed line for reconfigurable operation.

[0012] Furthermore, the receiving / radiating layer includes a plurality of symmetrically distributed periodic patches for receiving and radiating electromagnetic waves.

[0013] Furthermore, the sub-reflection unit includes a grid dielectric plate and a polarization grid arranged on the surface of the grid dielectric plate, wherein the polarization grid is a plurality of periodically arranged metal strips.

[0014] Furthermore, the microstrip patch antenna array feed source includes a dielectric plate, a patch antenna fixed on the surface of the dielectric plate, a feeding network connected to the patch antenna, and an SMA connector connected to the feeding network.

[0015] Furthermore, the antenna height, that is, the distance between the main reflector array and the secondary reflector array, is 2.16λ, where λ represents the working frequency band of the antenna. In addition, the ratio of the antenna height to the antenna size is 0.29.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention is based on liquid crystal tuning. Compared with PIN diodes, the present invention can be applied to future frequency bands and can be mass-produced using existing liquid crystal production lines, which has future application value and significance.

[0018] (2) The present invention adopts a new type of reflective metasurface unit, which has a novel unit design structure and is simpler than the existing PIN diode design structure. The unit is extended by using the feed line of the phase shift layer, the feed line and the upper orthogonal gap form a polarization converter, and the feed line and the lower liquid crystal layer form a liquid crystal phase shifter.

[0019] (3) The present invention adopts a new type of reflective metasurface unit. The unit design satisfies the 2-bit quantization scheme, which improves the aperture efficiency and control accuracy of the antenna array. Compared with the existing reconfigurable array, the aperture efficiency has a great advantage, that is, it achieves the advantages of low profile and easy integration while maintaining high aperture efficiency and excellent two-dimensional scanning capabilities. In addition, since the new reflective metasurface unit also has a polarization conversion function, it can be combined with a sub-reflection array to realize a folded array structure, thereby greatly reducing the profile height. Such a structure can integrate the antenna feed source and solve the problem of feed source shielding when the antenna radiates.

[0020] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0022] Figure 1 It is a schematic diagram of the overall structure of a 2-bit reconfigurable folded reflectarray antenna of an electrically controlled liquid crystal according to the present invention;

[0023] Figure 2 It is a schematic structural diagram of a novel reflective unit constituting a main reflective array of a reflective array antenna according to the present invention;

[0024] Figure 3 It is a schematic diagram of the working principle of the novel reflective unit constituting the main reflective array of the reflective array antenna according to the present invention;

[0025] Figure 4 It is a schematic structural diagram of the polarization grid unit constituting the sub-reflection array of the reflectance array antenna according to the present invention;

[0026] Figure 5 It is a schematic structural diagram of a microstrip antenna array constituting a radiation feed source of a reflectarray antenna according to the present invention;

[0027] Figure 6 This is a folding radiation principle diagram of a 2-bit reconfigurable folding reflectarray antenna of an electrically controlled liquid crystal according to the present invention;

[0028] Figure 7 A curve diagram showing the dielectric constant and dielectric loss value of the liquid crystal of the present invention changing with voltage;

[0029] Figure 8The four phase states corresponding to the 2-bit reconfigurable reflection unit of the present invention vary with frequency;

[0030] Fig. 9 The four reflection and transmission states corresponding to the 2-bit reconfigurable reflection unit of the present invention vary with frequency;

[0031] Fig.10 This is a graph showing the variation of the directivity coefficient of a 2-bit reconfigurable folded reflectarray antenna of an electrically controlled liquid crystal as a function of the scanning angle described in the present invention. Fig.10 (a) and Fig.10 (b) represents the scanning capability of the antenna in two planes.

[0032] Fig.11 (a)~( Fig.11 (e) are 3D simulation renderings of a 2-bit reconfigurable folded reflectarray antenna of an electrically controlled liquid crystal according to the present invention with beams pointing at 0°, 30°, 60°, -30°, and -60°.

[0033] Figure numerals: 1-main reflection array; 2-sub-reflection array; 3-microstrip patch antenna array feed; 4-reflection metasurface unit; 5-receiving / radiating layer; 6-upper dielectric plate; 7-orthogonal gap layer; 8-liquid crystal layer; 9-liquid crystal frame; 10-phase shift layer; 11-lower dielectric plate; 12-lower floor; 13-sub-reflection unit; 14-polarization grid; 15-grid dielectric plate; 16-patch antenna; 17-feed dielectric plate; 18-SMA connector; 19-injection hole; 20-air hole; 21-periodic patch; 22-differential feed line; 23-feeding network; 24-metal strip. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0035] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0036] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] like Figure 1 As shown, a 2-bit reconfigurable folded reflector array antenna of electrically controlled liquid crystal provided in one embodiment of the present invention mainly includes a main reflector array 1, a sub-reflector array 2 and a microstrip patch antenna array feed source 3. Among them, the microstrip patch antenna array feed source 3 is fixed at the center position of the main reflector array 1, occupying an area of ​​a unit size of 3×3 on the main reflector surface. In order to reduce the profile height and make the antenna easy to integrate, the feed source adopts a microstrip patch antenna array, which has the advantages of small size, easy processing, low profile, and easy integration. The main reflector array 1 includes N×N periodically arranged reflective metasurface units 4. In this embodiment, N is 15.

[0038] like Figure 2 and Figure 3 As shown, the structure of the reflective metasurface unit 4 includes a receiving / radiating layer 5, an upper dielectric plate 6, an orthogonal gap layer 7 for polarization conversion, a liquid crystal layer 8 for phase tuning, a phase shift layer 10 for completing phase tuning and polarization conversion, a lower dielectric plate 11, and a lower floor 12, which are stacked in sequence from top to bottom. Among them, a liquid crystal frame 9 for installing and separating liquid crystals is provided at the liquid crystal layer 8. In addition, in order to facilitate the later filling of liquid crystals, an injection hole 19 for liquid crystal filling and an air hole 20 for exhausting air are also designed at the lower floor 12.

[0039] like Figure 3As shown, a double-slot coupling unit is expanded by a single-slot coupling unit, and is combined with a phase shift layer 10 to form a new type of reflective metasurface unit 4. The unit is simulated using HFSS master-slave boundary conditions, and its working principle is: first, when receiving an X-polarized (Y-polarized) electromagnetic wave, the slot orthogonal to the X-polarized (Y-polarized) is excited, and the electromagnetic wave is coupled to a corresponding group of microstrip lines through the slot; secondly, when the electromagnetic wave coupled by the microstrip line is transmitted in the phase shift layer 10, by adjusting the control module, the voltage between the liquid crystal layer 8 is changed, and the dielectric constant of the liquid crystal can be controlled to change, thereby changing the phase of the electromagnetic wave transmitted in the microstrip line; then, when the electromagnetic wave that completes the predetermined phase compensation is transmitted to another group of microstrip lines, the slot orthogonal to the receiving slot is excited by this group of microstrip lines, and the Y-polarized (X-polarized) electromagnetic wave is excited, and then the polarization conversion is completed; finally, the electromagnetic wave that completes the polarization conversion and phase compensation is radiated secondary through the receiving / radiating layer 5.

[0040] According to the structure and radiation principle of the folded reflective array, the component unit of the sub-reflective array 2 is a polarization grid 14 that can transmit X / Y polarized waves and reflect Y / X polarized waves, such as Figure 4 As shown. The sub-reflection unit 13 uses a grid dielectric plate 15 with a relative dielectric constant of 3.66, and its metal strips 24 are periodically distributed on the surface of the dielectric plate. The operating frequency band and frequency selection performance of the polarization grid 14 are determined by the size of the metal strips 24 and the periodic interval gaps. The normally incident Y polarized wave is almost completely reflected by the polarizer, while for the X polarized wave, a high transmission amplitude can be obtained within the frequency band.

[0041] like Figure 5 As shown, a microstrip patch antenna array feed source 3 provided in an embodiment of the present invention is composed of a microstrip patch antenna array. The patch antennas 16 are combined by a feeding network 23, and the patch antennas 16 are fed by an SMA connector 18.

[0042] Reference Figure 6 and Figure 1When the feed radiates, the folded reflectarray antenna consists of three parts: a main reflector composed of reflective units with polarization twist and phase compensation functions, an actual feed, and a polarization grid with polarization selection function. By setting a polarization grid above the main reflector, the X-polarized (Y-polarized) electromagnetic wave is transmitted through the grid, and the required beam of another Y-polarized (X-polarized) is reflected by the grid to the array surface with polarization twist and phase compensation functions. The X-polarized (Y-polarized) beam formed after phase compensation and polarization twist passes through the grid again. Since the polarization of the beam is converted, the required new beam after polarization twist and phase compensation is transmitted through the grid and radiated in the direction of the shaping. According to the principle of ray tracing, since the antenna undergoes secondary reflection, the antenna cross section is reduced to half of that of an ordinary reflectarray antenna. According to the equivalent principle, the virtual feed is located at the position of the traditional reflectarray, and the actual feed is located on the main reflectarray of the antenna. The cross-sectional height H is reduced by 1 / 2 without greatly affecting the antenna performance. At the same time, this structure also makes it easy to place the feed on the reflecting surface. By replacing the horn feed with a microstrip patch antenna array feed, it facilitates the integrated design of the antenna and solves the problem of radiation shielding of the traditional reflector array antenna, so that the beam scanning is not affected in the main radiation area.

[0043] In order to achieve the desired radiation beam when the array radiates, it is necessary to accurately calculate the compensation phase distribution on the main transmission surface to obtain the desired beam, thereby realizing beam scanning. For the calculation method of phase compensation of different units on the transmission array, according to the coordinate system xyz, assuming that the beam direction of the antenna is From the theory of array antennas, we know that the phase compensation calculation formula of the transmission array is as follows:

[0044]

[0045] Among them, φ R (x i ,y i ) is the compensation phase required for the ith unit, (x i ,y i ) is the coordinate of the ith unit, k0 is the propagation constant in vacuum, d i is the distance from the phase center of the feed to the center of the ith unit. Assume that the coordinates of the phase center of the feed are (x f ,y f ,z f ), then d i The calculation formula is as follows:

[0046]

[0047] like Figure 7As shown, in order to make the unit obtain the above phase distribution, the transmission unit needs to be tuned by liquid crystal. The working principle of the phase shift layer of this unit is based on the liquid crystal inverted microstrip line. The liquid crystal molecules are rod-shaped. The liquid crystal molecules between the metal plates will be deflected by the voltage. Generally, the voltage state is divided into three types: bias voltage V b , starting voltage V th , cut-off voltage V sat When the bias voltage is less than the start voltage, the liquid crystal molecules are arranged horizontally due to the anchoring effect of the orientation layer. The dielectric constant at this time is expressed as ε r,⊥ As the voltage gradually increases, when the bias voltage is greater than the cut-off voltage, the liquid crystal molecules deflect to the maximum angle, and the dielectric constant at this time is expressed as ε r,|| When the bias voltage is between the cut-off voltage and the start-up voltage, the liquid crystal molecules are in an intermediate state, and the dielectric constant of the liquid crystal layer increases with the increase of the voltage. However, this state is not linear. The parameters of the SM65-1 type liquid crystal used in the present invention at 24GHz are (ε r,⊥ =2.54,tanε r,⊥ =4.8E-03,ε r,|| =3.48,tanε r,|| =2.7E-03).

[0048] The liquid crystal phase shifter used in the present invention is in the form of a strip line. The phase compensation of the liquid crystal phase shifter is related to the length of the phase shift layer. Through optimization design, a phase change greater than 270° can be obtained to achieve 2-bit quantization. The phase shifter is cut at the bend to reduce the discontinuity at the bend.

[0049] According to the dielectric properties of liquid crystal, the tunability of liquid crystal material is given by,

[0050]

[0051] According to the microstrip line theory of nematic liquid crystal phase shifter, the electrical length of the phase shifter φ l It can be expressed as follows:

[0052] jφ l =rl p

[0053] Where r = (α + jβ) is the complex propagation constant, including the attenuation constant α and the propagation constant β. p is the physical length of the microstrip line.

[0054] The electrical length can be further expressed as follows:

[0055]

[0056] Where f0 is the central operating frequency and c0 is the speed of light in a vacuum. r,eff ≈1, and liquid crystal is a low-loss medium in the millimeter wave frequency band, so the loss can be ignored. Finally, the formula for the phase shift is as follows:

[0057]

[0058] where ε r,eff It is a voltage-adjustable variable. The differential phase shift Δφ can be obtained according to the bias voltage and the dielectric constant corresponding to the bias voltage. l , which can be obtained from the following formula:

[0059]

[0060] The phase shift layer can be designed by utilizing the above liquid crystal principle in combination with the structure of the reflective unit. After careful design and optimization, a phase change of more than 270° can be obtained.

[0061] When the radiation direction of the reflected wave is θ m By determining, we can get the reflection phase Φ required by the reflection unit in the i-th column and j-th row. R (X ij ), when 0<Φ R (X ij )<90°, the phase of the cell in the i-th column and j-th row is adjusted to state “1”. R (X ij )<180°°, adjust the phase of the cell in the i-th column and j-th row to state "2". When 180°≤Φ R (X ij )<270°, adjust the phase of the cell in the i-th column and j-th row to state "3". When 270°≤ R (X ij )<360°, adjust the phase of the unit in the i-th column and the j-th row to state "4". According to the above principle, the N×N columns of reflection units of the main reflection array 1 are arranged with 2-bit coding, so that the radiation pattern can point to a specific direction. Changing the coding sequence can realize the reconfigurable characteristic of the antenna radiation pattern.

[0062] The following is a further description of the technical effects of the present invention in combination with the simulation results:

[0063] 1. Simulation conditions

[0064] HFSS, 3D electromagnetic field simulation software. Multi-purpose full-wave 3D electromagnetic (EM) simulation software, used to design and simulate high-frequency electronic products, such as antennas, components, interconnects, connectors, ICs, and PCBs. In the embodiments of the present invention, the HFSS microwave simulation function is used to simulate and analyze the reflection coefficient, reflection phase, and radiation pattern of the antenna.

[0065] 2. Reflection unit simulation content

[0066] Figure 8 and Fig. 9 The figure is a simulation result diagram of the new reflective metasurface unit proposed in the present invention at 23GHz to 26GHz, with normal incident waves with X polarization and Y polarization (modes 1 and 2) acting on the unit. Due to the symmetry of the unit structure, only the simulation results under the condition of Y polarization incident wave are shown. The simulation results are shown in Figure 8 and Fig. 9 As shown. 11 Indicates the case where one port is incident and one port is output, that is, the incident wave is reflected. xy It indicates the ability of the unit to convert the incident wave into an X-polarized wave when a Y-polarized wave is incident. By changing the dielectric constant of the liquid crystal, the four phase states change linearly over a wide frequency range, which is beneficial to the regulation of the antenna. The phase difference between state 1 and state 4 is greater than 270°, and the phases in two adjacent states meet the requirements of 2-bit phase quantization. The results also indicate the situation of reflecting the Y-polarized wave and the ability of the unit to convert the Y-polarized incident wave into an X-polarized wave when a Y-polarized wave is incident. In the range of 23 GHz to 26 GHz, the reflective metasurface unit has good polarization conversion capability and sufficient control phase difference.

[0067] 3. Reflection array simulation content

[0068] Fig.10 FIG. 1 is a graph showing the variation of the directivity coefficient of the reconfigurable folded reflectarray antenna proposed by the present invention with the scanning angle, wherein Fig.10 (a) and Fig.10 (b) shows the scanning capability of the antenna in two planes. Good two-dimensional beam scanning capability can be achieved from -60° to 60°.

[0069] Fig.11 The figure shows the 3D simulation effect of the reconfigurable folded reflector array antenna proposed by the present invention with the beam pointing at 0°, 30°, 60°, -30°, and -60°. Fig.11 As shown in (a), 11(b), 11(c), 11(d), and 11(e), the antenna exhibits good beam radiation capability at various scanning angles.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A 2-bit reconfigurable folded reflector array antenna of an electrically controlled liquid crystal, comprising a main reflector array (1), a sub-reflector array (2), and a microstrip patch antenna array feed source (3) located in the middle area of ​​the main reflector array (1), wherein a column is provided between the main reflector array (1) and the sub-reflector array (2) for support; characterized in that: The main reflection array (1) comprises a plurality of periodically arranged and mutually independent reflection metasurface units (4), wherein the reflection metasurface units (4) are used to perform polarization conversion and phase compensation on incident electromagnetic waves; the sub-reflection array (2) comprises periodically arranged sub-reflection units (13) which are used to transmit polarized waves inconsistent with a feed source and reflect polarized waves consistent with a feed source.

2. The 2-bit reconfigurable folded reflectarray antenna according to claim 1, characterized in that: The reflective metasurface unit (4) comprises a receiving / radiating layer (5), an upper dielectric plate (6), an orthogonal gap layer (7) for polarization conversion, a liquid crystal layer (8) for phase tuning, a phase shift layer (10) for cooperating to complete phase tuning and polarization conversion, a lower dielectric plate (11) and a lower floor (12) which are stacked in sequence from top to bottom; the liquid crystal layer (8) is provided with a liquid crystal frame (9) for mounting a partitioned liquid crystal.

3. The 2-bit reconfigurable folded reflectarray antenna according to claim 2, characterized in that: The phase shifting layer (10) comprises a group of differential feed lines (22) with a bent structure and centrally symmetrical distribution.

4. The 2-bit reconfigurable folded reflectarray antenna according to claim 2, characterized in that: The receiving / radiating layer (5) comprises a plurality of symmetrically distributed periodic patches (21).

5. The 2-bit reconfigurable folded reflectarray antenna according to claim 1, characterized in that: The sub-reflection unit (13) comprises a grid dielectric plate (15) and a polarization grid (14) arranged on the surface of the grid dielectric plate (15).

6. The 2-bit reconfigurable folded reflectarray antenna according to claim 5, characterized in that: The polarization grid (14) is a plurality of periodically arranged metal strips (24), and the width and spacing of the metal strips (24) are related to the working frequency band of the antenna.

7. The 2-bit reconfigurable folded reflectarray antenna according to claim 1, characterized in that: The microstrip patch antenna array feed source (3) comprises a dielectric plate, a patch antenna (16) fixed to the surface of the dielectric plate, a feeding network (23) connected to the patch antenna (16), and an SMA connector (18) connected to the feeding network (23).

Images