An electrically controlled liquid crystal 2-bit reconfigurable folded transmissive array antenna

Abstract

The application relates to the technical field of reconfigurable communication antenna devices, and particularly discloses a high-aperture-efficiency low-profile reconfigurable folded transmission array antenna design based on liquid crystals. The application aims to solve the problems of insufficient aperture efficiency and high profile in the existing reconfigurable folded array. The application designs a novel transmission unit, which integrates upper and lower radiation and receiving patches with polarization selection function and a liquid crystal phase shifter based on a strip line to realize phase compensation. In order to minimize the profile height, the main transmission array is composed of the novel transmission unit, while the auxiliary reflection array adopts a polarization conversion unit, and the interaction between the two is used to fold the transmission path of electromagnetic waves. At the same time, a microstrip patch antenna replaces the traditional horn antenna as the array feed source to reduce the overall profile. In order to improve the aperture efficiency, the liquid crystal phase shifter is carefully optimized to meet the requirement of 2-bit phase quantization, so as to improve the phase modulation accuracy and the accuracy of array phase distribution. Compared with the traditional space feed antenna and the folded array, the overall profile of the design is reduced by 2 / 3, the aperture efficiency is significantly improved, and excellent two-dimensional beam scanning performance is maintained.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of reconfigurable communication antenna devices, and particularly relates to a 2-bit reconfigurable folded transmissive array antenna of electrically controlled liquid crystal. BACKGROUND

[0002] With the increasingly tense communication frequency band resources and the increasing number of communication devices, the future frequency band will face serious channel attenuation problems. High-gain antennas are the key to communication construction, and the common solution is to use array antennas. However, the traditional array antenna is usually large in size and is not suitable for compact environments. Therefore, it is of great significance to research and design a high-gain, low-profile and more compact array antenna for future communication. In addition, with the increasing complexity of communication and electromagnetic environment, the reconfigurability of the antenna has also become the focus of future communication system construction. The antenna with reconfigurability can intelligently adjust the radiation direction and concentrate energy in the target area. However, existing research shows that the current reconfigurable antenna still faces challenges in realizing low profile and high aperture efficiency. Therefore, it is necessary to design an antenna with reconfigurability, high gain and small size (low profile) to cope with the increasingly complex communication environment.

[0003] There are a large number of researches on reconfigurable arrays, including reconfigurable reflective arrays and transmissive arrays. However, most of the existing researches adopt PIN diode scheme, and with the complication of functions, the number of PIN diodes required increases, which leads to the difficulty of designing the feed network and significantly increases the cost of the antenna. The traditional reconfigurable array usually adopts the space feed method from the top or the bottom, which is difficult to realize integration and has a high profile. To solve this problem, existing researches have tried to introduce a folding structure into the array design, but most of these schemes are still based on PIN diode technology. Due to the limitation of the number of PIN diodes, these schemes usually adopt a 1-bit quantization scheme, resulting in a gain loss of about 3dB. Using multiple PIN diodes can achieve high-bit quantization, but the array design requires multiple feed lines, making it difficult to design an array with hundreds of units, so only 1-bit quantization can be used. Due to the insufficient phase modulation accuracy, the gain of the antenna array causes certain attenuation, which is contrary to the original intention of designing the array antenna to improve the gain. The 3dB gain attenuation is unacceptable when converted to the antenna, and half of the energy is lost. In future communication frequency bands, due to the reduction of wavelength, the loss of free space of electromagnetic waves is extremely large, and such gain loss is unacceptable. Therefore, it is particularly important to design an array antenna with higher quantization scheme, higher gain, lower profile and reconfigurability. SUMMARY

[0004] In view of the problems of complex antenna structure, PIN diode generally used, high profile, difficulty in integration and low aperture efficiency of other reconfigurable transmissive array antennas in the prior art, the application discloses a high-aperture-efficiency low-profile reconfigurable folded transmissive array antenna based on liquid crystal. The technical scheme effectively reduces the profile height of the transmissive array antenna (reduces to 1 / 3 of the original array profile height), successfully solves the integration problem through the folded structure design, improves the aperture efficiency of the antenna, and maintains good two-dimensional beam scanning performance. Compared with the traditional PIN diode, the liquid crystal material modulation scheme adopted in the application has a wider application prospect and can adapt to the needs of future frequency bands. Therefore, the application has important reference value and application potential in the field of reconfigurable array antennas.

[0005] The 2-bit reconfigurable folded transmissive array antenna of the application comprises a main transmissive array, a sub-reflection array and a microstrip patch antenna feed.

[0006] To achieve the above advantages, the technical scheme of the application is as follows:

[0007] A new type of transmissive unit of the main transmissive array is designed, and the unit period is set to 5mm (greater than half of the free space wavelength of 28ghz). The main transmissive array is provided with a plurality of groups of new type of transmissive array units arranged and independent of each other. The units all adopt a 2-bit phase quantization scheme.

[0008] The transmissive array unit is composed of 15 parts from top to bottom, i.e., a receiving patch, an upper dielectric plate (with a dielectric constant of 3.66), an upper metal ground, a liquid crystal layer, a liquid crystal frame (with a dielectric constant of 2.2), a phase-shifting layer, a lower metal ground, a lower dielectric plate (with a dielectric constant of 3.66), a radiation patch, an upper dipole patch, a lower dipole patch, an upper metal column, an upper conversion column, a lower metal column, and a lower conversion column. The sub-reflection array unit is composed of a polarization conversion structure and a dielectric plate layer (with a dielectric constant of 3.5) and a ground plate.

[0009] The feed adopts a microstrip patch antenna structure, and the microstrip patch antenna is installed at the center of the sub-reflection array and occupies the size area of 3*3 sub-reflection units.

[0010] The new type of transmissive unit is composed of a liquid crystal phase shifter (the function is realized by combination of a liquid crystal layer and a phase-shifting layer) and a polarization selection layer (upper and lower dipole patches and upper and lower conversion columns). The new type of transmissive unit has an adjustable phase difference range of more than 270°, and the unit has both the functions of adjusting the phase difference and selecting the polarization.

[0011] The phase-shifting layer of the novel transmission unit receives electromagnetic waves from the upper layer receiving patch through the upper layer conversion column and cooperates with the liquid crystal layer to complete phase difference adjustment. The electromagnetic waves completing the phase difference adjustment are transmitted to the lower layer radiation patch through the lower layer conversion column. The upper layer conversion column passes through the upper layer dielectric layer and then passes through a hole with a slightly larger radius than itself to connect with the phase-shifting layer through the upper layer metal ground. In the same way, the lower layer conversion column is also connected with the lower layer metal ground in the same way.

[0012] The phase-shifting layer of the novel transmission unit is connected with the upper and lower conversion columns by winding around the upper and lower metal columns, and the strip line of the phase-shifting layer is cut at an angle to reduce the discontinuity at the bending part. The place where the phase-shifting layer is connected with the upper and lower conversion columns is replaced with a disc with a slightly larger radius than the conversion column for impedance matching.

[0013] The upper and lower metal grounds and the liquid crystal frame of the novel transmission unit wrap the liquid crystal and the phase-shifting layer to form a liquid crystal strip line phase shifter. The metal ground is slightly smaller than the size of the dielectric layer to facilitate the design of the later feed network.

[0014] The sub-reflection array unit constituting the sub-reflection array is divided into two groups by four metal strips arranged at a certain angle to form a polarization conversion structure. The angle between the metal strips in one group is 38°, and the metal strips are on the upper layer of the dielectric plate. The lower layer of the dielectric plate is covered with a metal ground.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] The transmission array antenna described in the present application is tuned based on liquid crystal, which is different from the PIN diode in the past. It 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.

[0017] Compared with the reconfigurable array in the prior art, the present application adopts a novel transmission array unit, which has a novel design structure and uses the feed line of the phase-shifting layer for expansion. The upper and lower metal grounds and the liquid crystal layer form a liquid crystal-based strip line phase shifter, which cleverly realizes the function of adjusting the phase difference of the unit. The design structure is novel, and the transmission loss is low.

[0018] Compared with the reconfigurable array in the prior art, the present application adopts a novel transmission array unit, which is designed based on magnetic dipoles. The upper and lower layers of the unit use magnetic dipole units to radiate and receive electromagnetic waves, which widens the bandwidth of the unit.

[0019] Compared with the reconfigurable array in the prior art, the present application adopts a novel transmission array unit, which uses two oppositely arranged receiving and radiation patches to realize selection and radiation of the same polarized wave, and cleverly realizes the polarization selection function.

[0020] Compared with the reconfigurable array in the prior art, the application adopts a new type of transmission array unit which can meet the design requirements of the 2-bit quantization scheme, significantly improves the regulation accuracy of the array, makes the phase distribution of the antenna array more accurate, and thus improves the aperture efficiency. Compared with the existing reconfigurable array, the application has a significant advantage in aperture efficiency, successfully realizes the balance of high aperture efficiency and excellent two-dimensional scanning capability, and has the advantages of low profile and easy integration. In the two-dimensional space, the application can realize a scanning range of-60° to 60°. Compared with the Ka-band transmission phased array antenna based on liquid crystal designed by the University of Electronic Science and Technology, although both use liquid crystal 2-bit transmission array technology, the document adopts two layers of liquid crystal layers, resulting in a complex structure and a high profile. The application only uses one layer of liquid crystal tuning layer, and the structure is simpler. In addition, the application adopts a folded array structure, and through the interaction between the sub-reflection array and the main transmission array, the transmission path of the electromagnetic wave is folded, the antenna profile height is reduced to 1 / 3 of the traditional transmission array, and finally the profile height is only 1.5λ (corresponding to the free space wavelength at 24GHz), the focal length ratio is 0.24, and the simulation peak aperture efficiency reaches 30%. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The whole structure schematic diagram of the 2-bit reconfigurable folded transmission array antenna of the electrically controlled liquid crystal according to the application;

[0022] Figure 2 The structure schematic diagram of the new type of transmission unit of the 2-bit reconfigurable folded transmission array antenna of the electrically controlled liquid crystal according to the application;

[0023] Figure 3 The structure schematic diagram of the polarization conversion unit of the sub-reflection array of the 2-bit reconfigurable folded transmission array antenna of the electrically controlled liquid crystal according to the application;

[0024] Figure 4 The structure schematic diagram of the microstrip patch antenna of the radiation feed source of the 2-bit reconfigurable folded transmission array antenna of the electrically controlled liquid crystal according to the application;

[0025] Figure 5 The folded radiation principle diagram of the 2-bit reconfigurable folded transmission array antenna of the electrically controlled liquid crystal according to the application;

[0026] Figure 6 The four phase state frequency change curves corresponding to the 2-bit reconfigurable transmission unit according to the application;

[0027] Figure 7 The simulation performance diagram of the polarization conversion unit of the sub-reflection array of the 2-bit reconfigurable folded transmission array antenna of the electrically controlled liquid crystal according to the application;

[0028] Figure 8 These are the frequency variation curves for the four transmission states corresponding to the 2-bit reconfigurable transmission unit described in this invention;

[0029] Figure 9 This is a graph showing the variation of the directivity coefficient of the 2-bit reconfigurable foldable transmission array antenna of the electro-controlled liquid crystal as described in this invention with the scanning angle.

[0030] Figure 10 a, 10b, 10c and Figure 10 d is a 3D simulation diagram of the beam pointing of a 2-bit reconfigurable foldable transmission array antenna of an electronically controlled liquid crystal according to the present invention, with beam pointing at 0deg, 30deg, and maximum angles of 60deg and -60deg.

[0031] Reference numerals: 1-Main transmission array, 2-Sub-reflection array, 3-Feed source, 4-Novel transmission unit, 5-Receiver plate, 6-Upper dielectric substrate, 7-Upper metal ground, 8-Liquid crystal layer, 9-Liquid crystal frame, 10-Phase shifting layer, 11-Lower ground plane, 12-Lower dielectric substrate, 13-Radiating patch, 14-Upper dipole patch, 15-Lower dipole patch, 16-Upper metal pillar, 17-Upper conversion pillar, 1 8-Lower metal pillar, 19-Lower conversion pillar, 20-Sub-reflector array element, 21-Polarization conversion structure, 22-Dielectric substrate layer, 23-Metal ground plane, 24-Microstrip patch antenna, 101-Circular piece of conversion pillar, 131-Upper magnetic dipole, 141-Lower magnetic dipole, 241-Patch antenna, 242-Feed network, 243-Dielectric substrate, 244-Ground plane, 245-SMA connector. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Reference Figure 1 This invention includes a main transmission array 1, a sub-reflection array 2, and a microstrip patch antenna feed 3. The feed 3 is fixed at the center of the sub-reflection array 2, occupying a 3×3 element area of ​​the main and sub-reflection array surfaces. The feed 3 uses a microstrip patch antenna 24, which has a simple structure, stable radiation beam, and easy beam control. The profile height of the array is determined by the radiation beam angle of the microstrip patch antenna 24, and also needs to be designed in conjunction with the sub-reflection array.

[0034] The main transmission array 1 includes N×N periodically arranged reconfigurable transmission elements 4, where N is 13 in this example;

[0035] Reference Figure 2The novel transmission unit 4 comprises: an upper dielectric plate (6) provided with a receiving patch (5) on its upper surface; an upper metal ground (7) below the upper dielectric plate (6); a liquid crystal frame (9) below the upper metal ground (7); a lower metal ground (11) below the liquid crystal frame (9); a lower dielectric plate (12) below the lower metal ground (11), which is provided with a radiation patch (13) on its lower surface. A liquid crystal layer (8) is encapsulated between the upper metal ground (7) and the lower metal ground (11), and a phase shift layer (10) is arranged. The receiving patch (5) is electrically connected to the upper metal ground (7) through at least one upper metal column (16), and the upper metal column (16) is provided with an upper dipole patch (14) around it. The radiation patch (13) is electrically connected to the lower metal ground (11) through at least one lower metal column (18), and the lower metal column (18) is provided with a lower dipole patch (15) around it. One end of the phase shift layer (10) is electromagnetically coupled to the receiving patch (5) through an upper conversion column (17), and the other end is electromagnetically coupled to the radiation patch (13) through a lower conversion column (19); the upper conversion column (17) passes through the through holes in the upper dielectric plate (6) and the upper metal ground (7) in sequence, and the lower conversion column (19) passes through the through holes in the lower dielectric plate (12) and the lower metal ground (11) in sequence. The upper dipole patch (14), the upper metal column (16) and the receiving patch (5) together form an upper magnetic dipole (131), and the lower dipole patch (15), the lower metal column (18) and the radiation patch (13) together form a lower magnetic dipole (141).

[0036] Referring to Figure 3 The auxiliary reflective array unit 20 is composed of a polarization conversion structure 21 and a dielectric plate layer 22. The polarization conversion structure is composed of four metal strips arranged in two groups at a certain angle. The included angle between the metal strips in one group is 38°, and the metal strips are arranged on the upper layer of the dielectric plate layer 22. The lower layer of the dielectric plate is covered with a metal ground plate 23. The structure can realize polarization conversion in a wide band of 26GHz-31GHz.

[0037] Referring to Figure 4 The microstrip patch antenna 24 is used as the feed source of the antenna array for radiation. The feed source antenna structure is simple, and the profile height of the array is determined by the radiation ability of the microstrip patch antenna. The microstrip patch antenna is composed of a patch antenna 241, a feed network 242, a dielectric plate 243 and a ground plate 244. In order to facilitate feeding, a back SMA connector 245 is used for feeding.

[0038] Referring to Figure 5 Combined with Figure 1The explanation is as follows: the folded transmission array is composed of three parts, a main transmission surface composed of transmission units with polarization selection and phase compensation function, an actual feed, and a sub-reflection array unit with polarization conversion function. The microstrip patch antenna located on the sub-reflection array radiates X-polarized (Y-polarized) electromagnetic waves to the main transmission surface. Electromagnetic waves with the same polarization as the main transmission array unit are reflected, and electromagnetic waves with opposite polarization to the main transmission array unit are directly transmitted. After the X-polarized (Y-polarized) electromagnetic waves are radiated to the sub-reflection array, the X-polarized (Y-polarized) beams are converted to Y-polarized (X-polarized) beams by the polarization conversion unit. The electromagnetic waves that have completed polarization conversion are radiated to the main transmission array surface again. Due to the polarization conversion of the beams, the new beam transmission required by the polarization twist transmits through the main transmission array, and the phase shifter of the main transmission array unit compensates the phase of the new electromagnetic waves. The electromagnetic waves that have completed phase compensation are radiated according to the assigned direction. According to the principle of ray tracing, since the antenna is reflected twice, and due to the difference between the phase compensation array and the reflection array, the antenna profile is reduced to 1 / 3 of the ordinary transmission array antenna. According to the equivalent principle, the virtual feed is located at the position of the conventional transmission array, and the actual feed is located at the center position of the sub-reflection array of the antenna. The profile height H is reduced by 2 / 3, and the antenna performance is not greatly affected. At the same time, this structure also facilitates the placement of the feed on the sub-reflection array, facilitating the integration of the antenna, and making the beam scanning in the main radiation area unaffected.

[0039] According to the above description, the transmission array unit needs to have phase compensation and polarization selection functions, and the sub-reflection array unit needs to have polarization conversion function.

[0040] In order to realize the desired radiation beam when the array radiates, the compensation phase distribution on the main transmission surface is accurately calculated by the following formula 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, it is assumed that the beam direction of the antenna is According to the theory of array antenna, the phase compensation calculation formula of the transmission array is as follows: where φ R (x i , y i ) is the compensation phase required by the i-th unit, (x i , y i ) is the coordinate of the i-th 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 i-th unit. Assuming that the coordinates of the phase center of the feed are (x f , y f , z f ), then the calculation formula of d i is as follows:

[0041]

[0042]

[0043] In order to make the unit get the above phase distribution, the transmission unit needs to be tuned by liquid crystal, and the working principle of the phase shift layer of the unit is based on liquid crystal inverted microstrip line, the liquid crystal molecules are rod-shaped, and the liquid crystal molecules between the metal plates are deflected under the control of voltage. Generally, the voltage state is divided into three kinds, bias voltage V b , start voltage V th , and cutoff voltage V sat . When the bias voltage is less than the start voltage, the liquid crystal molecules are horizontally arranged due to the anchoring effect of the orientation layer, and the dielectric constant at this time is represented as ε r，⊥ . With the gradual increase of the voltage, when the bias voltage is greater than the cutoff voltage, the liquid crystal molecules are deflected to the maximum angle, and the dielectric constant at this time is represented as ε r，|| . When the bias voltage is between the cutoff voltage and the start 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 simulation parameters of the liquid crystal used in the present application at 24GHz are (ε r，⊥ =2.5, tanδε r，⊥ =4.8E-03, ε r，|| =3.5, tanδε r，|| =2.7E-03).

[0044] The liquid crystal phase shifter used in the present application adopts a strip line form, and the phase difference provided by 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 realize 2-bit quantization. The corner cutting is performed at the bending part of the phase shifter to reduce the discontinuity at the bending part.

[0045] When the radiation direction θ m of the transmission wave is determined, the transmission phase Φ R (x ij ) required by the i-th column and j-th row transmission unit can be obtained. When 0°≤Φ R (x ij )<90°, the phase of the i-th column and j-th row unit is adjusted to state "0"; when 90°≤Φ R (x ij )<180°, the phase of the i-th column and j-th row unit is adjusted to state "1"; when 90°≤Φ R (x ij )<180°, the phase of the i-th column and j-th row unit is adjusted to state "3"; and when 180°≤Φ R (x ij)<270°, the phase of the cell in the ith column and jth row is adjusted to state "4", according to the above principle, 2-bit coding arrangement is performed on the N*N column transmission cells, the directional diagram can be directed to a specific direction, and the reconfigurable characteristic of the antenna directional diagram can be realized by changing the coding sequence. Based on the above method, 2-bit quantization can be completed on the array, and good two-dimensional scanning capability can be realized.

[0046] The technical effects of the application are further described below in combination with simulation results:

[0047] Simulation conditions:

[0048] HFSS, a three-dimensional electromagnetic field simulation software. A multi-purpose full-wave 3D electromagnetic (EM) simulation software for designing and simulating high-frequency electronic products, such as antennas, components, interconnections, connectors, ICs and PCBs. The microwave simulation function of HFSS is used in the examples of the application to simulate and analyze the transmission coefficient, transmission phase and directional diagram of the antenna unit.

[0049] Simulation content:

[0050] Reference Figure 6 is a simulation result diagram of the novel transmission unit proposed in the application at 26GHz-31GHz, and the normally incident wave with X polarization and Y polarization (modes 1 and 2) acts on the unit. The simulation results are shown in Figure 6 By changing the dielectric constant of the liquid crystal, the phase of the four states changes linearly in a wide frequency range, the phase difference between state 1 and state 4 is greater than 270°, and the phase of the adjacent two states meets the requirement of 2-bit phase quantization. It is beneficial to the control of the antenna. In the range of 26GHz to 31GHz, there is enough control phase difference.

[0051] Reference Figure 7 is a simulation result diagram of the transmission and reflection performance of the novel transmission unit proposed in the application at 26GHz-31GHz. It can be seen that when the radiation condition is Y polarized wave incidence, the antenna has the ability to reflect X polarized wave to receive Y polarized wave. It shows that the transmission unit has good polarization selection function and meets the structural requirements.

[0052] Reference Figure 8 is a performance simulation diagram of the polarization conversion unit of the sub-reflector array of the array antenna according to the application. It can be seen that in the wideband range of 26GHz-31GHz, the unit has good polarization conversion capability, and the incident Y polarized electromagnetic wave is converted into X polarized electromagnetic wave.

[0053] Reference Figure 9The figure shows the variation of the directivity coefficient of the liquid crystal-based high-aperture-efficiency low-profile reconfigurable folded transmissive array antenna described in the present application with the scanning angle. It can be seen that the antenna array has good beam scanning capability. According to the symmetry principle, only the scanning capability of one face is shown here.

[0054] Reference Figure 10 a, 10b, 10c and Figure 10 d is the 3D simulation effect diagram of the 2-bit reconfigurable folded transmissive array antenna beam pointing 0 deg, 30 deg and the maximum angle 60 deg and -60 deg described in the present application. The beam scanning capability of the array antenna is more clearly shown.

Claims

1. An electrically controlled liquid crystal 2-bit reconfigurable folded transmissive array antenna, comprising a main transmissive array (1), a sub-reflection array (2) and a microstrip patch antenna feed (3), characterized in that: a plurality of groups of periodically arranged and independently controlled novel transmissive array units (4) are arranged on the main transmissive array (1); the novel transmissive array unit (4) comprises: an upper dielectric plate (6) with a receiving patch (5) arranged on its upper surface; an upper metal ground (7) located below the upper dielectric plate (6); a liquid crystal frame (9) located below the upper metal ground (7); a lower metal ground (11) located below the liquid crystal frame (9); a lower dielectric plate (12) located below the lower metal ground (11), with a radiation patch (13) arranged on its lower surface; a liquid crystal layer (8) is encapsulated between the upper metal ground (7) and the lower metal ground (11), and a phase shift layer (10) is arranged, the liquid crystal layer (8) and the phase shift layer (10) together constitute a liquid crystal phase shifter; the receiving patch (5) is electrically connected to the upper metal ground (7) through at least one upper metal column (16), and an upper dipole patch (14) is arranged around the upper metal column (16); the radiation patch (13) is electrically connected to the lower metal ground (11) through at least one lower metal column (18), and a lower dipole patch (15) is arranged around the lower metal column (18); the upper dipole patch (14), the upper metal column (16) and the receiving patch (5) together constitute an upper magnetic dipole for receiving electromagnetic waves, the lower dipole patch (15), the lower metal column (18) and the radiation patch (13) together constitute a lower magnetic dipole for radiating electromagnetic waves, and the upper magnetic dipole and the lower magnetic dipole together constitute a polarization selection layer; one end of the phase shift layer (10) is electromagnetically coupled to the receiving patch (5) through an upper conversion column (17), and the other end is electromagnetically coupled to the radiation patch (13) through a lower conversion column (19); the upper conversion column (17) passes through the through holes in the upper dielectric plate (6) and the upper metal ground (7) in sequence, and the lower conversion column (19) passes through the through holes in the lower dielectric plate (12) and the lower metal ground (11) in sequence.

2. The electronically controlled liquid crystal 2-bit reconfigurable folded transmissive array antenna according to claim 1, wherein: The phase shift layer (10) is in a meandering line structure, and the bending part is provided with a cut corner treatment; the connection between the phase shift layer (10) and the upper conversion column (17) and the lower conversion column (19) is provided with an impedance matching disc (101).

3. The electronically controlled liquid crystal 2-bit reconfigurable folded transmissive array antenna according to claim 1, wherein: The upper metal ground (7), the liquid crystal frame (9) and the lower metal ground (11) together constitute a liquid crystal stripline phase shifter cavity for accommodating the liquid crystal layer (8) and the phase shift layer (10).

4. The electronically controlled liquid crystal 2-bit reconfigurable folded transmissive array antenna according to claim 1, wherein: The sub-reflection array (2) is composed of a plurality of sub-reflection array units (20), the sub-reflection array unit (20) comprises a dielectric plate layer (22), the upper surface of the dielectric plate layer (22) is provided with a polarization conversion structure (21), and the lower surface is covered with a metal floor (23); the polarization conversion structure (21) is composed of two groups of metal strips, and the included angle between the metal strips in one group is 38°.

5. The electronically controlled liquid crystal 2-bit reconfigurable folded transmissive array antenna according to claim 1, wherein: The microstrip patch antenna feed (3) comprises a patch antenna (241), a feed network (242), a dielectric plate (243) and a ground plate (244), and is fed from the bottom through an SMA joint (245).

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