An arbitrary linear polarized millimeter wave reconfigurable holographic metasurface unit structure and antenna array

Abstract

This invention discloses an arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface unit structure and antenna array, comprising, from top to bottom, a unit radiating patch, a first dielectric layer, a ground plane, a second dielectric layer, and a DC feed line layer. The unit radiating patch is square, with linear slots on its surface forming slot gaps. The two parts formed by the slots are connected by PIN diodes spanning the slot gaps, achieving linear polarization in the corresponding direction according to the slot direction. This invention enables an arbitrary linearly polarized leaky-wave antenna unit structure and array, operating in the millimeter-wave band, and can be used in millimeter-wave signal base stations for 5G mobile communication.

Description

Technical Field

[0001] This invention belongs to the field of antenna array technology, specifically relating to an arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface unit structure and antenna array. Background Technology

[0002] The 5G millimeter-wave band boasts abundant spectrum resources, and millimeter-wave communication, with its advantages of high capacity and high transmission quality, holds broad research prospects and commercial value in the 5G communication field. However, the millimeter-wave band suffers from problems such as high path loss and co-channel interference, necessitating the adoption of appropriate antenna technologies to effectively improve spectrum efficiency and compensate for some inherent defects of millimeter waves.

[0003] Currently, there are two main ways to realize millimeter-wave antennas. One is to use phased array antenna technology, which has the advantages of high gain, fast scanning speed and flexible control. The disadvantages are limited beam coverage and large beam differences. In addition, the traditional phased array front end requires a complex and expensive phase shift network and T / R components. Furthermore, it requires the integration of low-noise amplifiers, power amplifiers, phase shifters and other T / R components onto a high-performance, low-power, multi-channel chip, which places high demands on semiconductor materials and processing technology. The second method is to use lens antenna design, which has the advantages of low cost, wide bandwidth and simple feeding network. The disadvantages are complex design, large size and heavy weight.

[0004] Application CN202311211976.9 describes a millimeter-wave reconfigurable leaky-wave antenna based on liquid crystal. When a DC voltage or a low-frequency AC voltage is applied across the liquid crystal layer, the long axis orientation of the liquid crystal molecules changes with the voltage, thus altering the dielectric constant of the liquid crystal. When electromagnetic waves pass through a microwave device using this liquid crystal layer 2 as the transmission medium, the transmission characteristics of the electromagnetic waves change with the voltage change, thereby achieving the purpose of altering the transmission characteristics of the electromagnetic waves. However, this design uses liquid crystal material, resulting in a complex structure, high unit processing difficulty and cost, and the liquid crystal material is highly sensitive to temperature and humidity, exhibiting unstable electrical properties, making it difficult to use in large-scale industrial production. In contrast, this design does not require special materials like liquid crystal, can be implemented using conventional PCB processing, has a stable structure, and is insensitive to temperature and humidity changes.

[0005] In summary, the shortcomings of existing technologies are:

[0006] 1) Complex structural design. Traditional phased array and reconfigurable antennas have the problem of large overall size, and most of them have complex control circuits due to the need for electrical regulation of PIN diodes or varactor diodes; in addition, in order to reduce the impact of DC feed lines on radio frequency signals, most of them have complex structural designs and often adopt multi-layer composite structures.

[0007] 2) High cost. Traditional phased arrays require complex, highly integrated, and expensive phase shift networks to achieve beam scanning in the millimeter-wave band. Traditional reconfigurable antenna arrays require many surface-mount pin diodes, resulting in high overall cost.

[0008] 3) High manufacturing difficulty. Traditional phased array phase shift networks require highly integrated front-end devices onto a very small chip, thus placing extremely high demands on manufacturing processes. Traditional reconfigurable antenna arrays, due to the presence of DC feed lines, need to consider the separation of RF and DC signals. Furthermore, because the radiating elements in the millimeter-wave band are small, the corresponding DC feed lines also need to be further miniaturized. Generally, their multi-layered structure also places certain demands on manufacturing processes. Both are difficult to apply in large-scale industrial production.

[0009] 4) Small beam scanning angle and poor radiation stability. Existing leaky wave antenna arrays can only achieve fixed-angle beam scanning in the millimeter-wave band, or achieve beam scanning through frequency scanning. In general, their beam scanning angle is small, usually within ±30°, and the gain decreases significantly as the angle increases. Summary of the Invention

[0010] In order to overcome the shortcomings of the prior art, the present invention aims to provide an arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface unit structure and antenna array, which solves the problems of complex structure, high processing difficulty, high cost and small beam scanning angle in the prior art, and has the characteristics of simple structure, easy processing and production, low cost and large scanning angle.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A reconfigurable holographic metasurface antenna unit structure for arbitrary linear polarization millimeter waves includes, from top to bottom, a unit radiating patch, a first dielectric layer, a ground plane, a second dielectric layer, and a DC feed line layer.

[0013] The unit radiating patch is square with straight through slots on its surface, forming a slot gap. The two parts formed by the slot are connected by a PIN diode across the slot gap, and linear polarization is achieved according to the slot direction.

[0014] One or two PIN diodes are disposed on the slot gap of the unit radiating patch. When there are two, they have the same polarity. Two metallized through holes are symmetrically distributed along the slot gap to connect the unit radiating patch layer and the DC feed line layer. A DC control signal is introduced to regulate the on / off state of the PIN diodes. When the diodes are on, electromagnetic energy radiates outward along the slot gap. When the diodes are off, electromagnetic energy cannot radiate outward.

[0015] The DC feed line layer consists of two centrally symmetrical parts: an upper half and a lower half. The upper half connects to the DC control signal, while the lower half is cascaded together and connected to the metal plate of the intermediate layer via metallized vias. (Only one part of these two parts needs to be connected to the DC control signal (i.e., the positive terminal of the power supply), and the other part needs to be connected to the metal plate (connected to the negative terminal, i.e., ground). It is important to note that the part connected to the DC control signal is connected to the positive terminal of the PIN diode via a metallized via. In other words, the positive and negative polarity of the DC feed line layer must correspond to that of the PIN diode to control its conduction or cutoff.)

[0016] Each section of the DC feeder consists of three parts: a rectangular cross-section, a fan-shaped stub, and a circular pad.

[0017] The upper part of the circular pad is located on the rectangular cross-section and is connected to the metallized via. It is used to provide a better tight connection between the metallized via and the DC feed line. The diameter of the circular pad is slightly larger than that of the metallized via.

[0018] The fan-shaped stub is connected to the rectangular cross-section and is located on the rectangular cross-section. The fan-shaped stub is used to isolate the radio frequency signal on the DC feed line and reduce the loss of the radio frequency signal.

[0019] The rectangular cross-section is used to transmit DC control signals.

[0020] The lower half is obtained by rotating the upper half around the center of the unit.

[0021] The first dielectric layer, the ground plane, the second dielectric layer, and the DC feed line layer are all square with a side length of λ / 4; the rectangular radiating patch has a side length of λ / 12 to λ / 8.

[0022] The holographic metasurface antenna unit structure has a unit size of λ / 4, where λ = c / f is the wavelength corresponding to the required antenna operating frequency band, f is the frequency, and c is the speed of light in vacuum (3 x 10^8 m / s). The rectangular radiating patch 1 is smaller than the unit size, and its size is 1 / 3 to 1 / 2 of the unit size of the holographic metasurface antenna unit structure. Its thickness is approximately 1 mm (generally a multiple of 0.254 mm, because the minimum thickness of the material is 0.254 mm, and multiple layers of material are stacked during manufacturing).

[0023] The antenna's energy is radiated outward from the slots in the rectangular radiating patch, and different slot directions can achieve corresponding linear polarization angles.

[0024] The antenna array includes two subarrays, each composed of an arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface antenna element structure arranged along the X and Y directions, and the two subarrays are symmetrical about the X-axis. The arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface antenna element structure in each subarray has linear through slots in the same direction. The polarization of the two subarrays differs by 90°.

[0025] In each subarray, the DC feed lines are cascaded, with the positive terminal connected to the control board and the negative terminal grounded. The Y direction is defined as a column, so an entire column of PIN diodes has the same state.

[0026] The positive terminal of the DC feed line is connected to the FPC connector, which is located on the back of the array. It is used to introduce DC control signals to the control board via a flexible flat cable. The negative terminal is connected to the ground plane through a metallized through-hole. The control board outputs DC control signals to regulate the metasurface encoding state, thereby enabling the array beam to scan at different angles.

[0027] The rear structure of the antenna array adopts a single subarray RF feed port with two ports, and the two ports are connected to a power divider.

[0028] The antenna array employs tilting plates for impedance matching at the RF feed port of its front structure. This enables better overall impedance matching under different array coding conditions, ensuring that the S11 parameter of the port is below -10dB at different angles, thereby further improving the array's radiation efficiency.

[0029] A method for using an arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface antenna array includes the following steps;

[0030] Step 1: The control board outputs a specific DC control signal to modulate the on / off state of the PIN diodes on the array surface. If the digital state of the cell is "1", the DC control signal is a voltage that enables the PIN diode to conduct. When the PIN diode is on, energy cannot radiate outward from the slot gap. Conversely, when the PIN diode is off, energy radiates outward from the slot gap.

[0031] Step 2: When the control board outputs a voltage that enables the PIN diodes to conduct, the PIN diodes conduct, and an entire column in the X direction displays a digital state of "1"; conversely, an entire column displays a digital state of "0".

[0032] Metasurface units exhibit different digital state arrangements;

[0033] Step 3: The DC control signal is sent from the control board, passes through the DC feed line, passes through the metallized via, and finally arrives at both ends of the PIN diode of the unit radiating patch 1. The on / off state of the PIN diode is adjusted to make it present different digital states. Digital state "1" means that the PIN diode is on and energy cannot be radiated outward from the slot; digital state "0" means that the PIN diode is off and energy is radiated outward from the slot.

[0034] Step 4: Scan the array to the corresponding angle. Conversely, use this method to reverse the encoding of the beam scanning state.

[0035] Arbitrarily linearly polarized millimeter-wave reconfigurable holographic metasurface unit structure and antenna array, operating in the millimeter-wave frequency band, can be used as a millimeter-wave signal base station for 5G mobile communication.

[0036] The beneficial effects of this invention are:

[0037] 1. Millimeter-wave band beam scanning. In the millimeter-wave band, the higher the frequency, the greater the overall path loss. The dielectric loss of traditional transmission lines in the millimeter-wave band can significantly affect the signal. Traditional phased array antennas require complex and expensive transceiver (T / R) components, which are difficult to integrate into antenna arrays in the millimeter-wave band, and their miniaturization requires extremely high manufacturing precision. In contrast, leaky wave antenna structures combined with reconfigurable technology can achieve both low-loss signal transmission and flexible beam control, enabling wide-angle beam scanning.

[0038] 2. Simple and efficient design method. Through this reconfigurable antenna element structure and array design method, a reconfigurable leaky antenna array that operates in the millimeter-wave band and achieves any desired linear polarization direction can be designed quickly and efficiently.

[0039] 3. The overall structure is simple, easy to mass-produce, and low in cost. The antenna unit consists of three parts: a unit radiating patch, a DC feed line layer, and a ground plane. The structure is simple and the mechanical structure is robust, making it easy to manufacture and stably achieve its intended function. It is suitable for practical millimeter-wave base station applications.

[0040] 4. Optimization of RF ports. In order to further reduce the number of RF feed ports and thus reduce costs, the number of RF ports of a single subarray was reduced from 8 to 2 without affecting port matching and matching loss as much as possible. This allows the dual ports of the single subarray to realize the function of transmitting and receiving signals at the same time, and can also transmit (receive) RF signals simultaneously to obtain a high-gain beam.

[0041] 5. Optimization and simplification of DC feed lines. Adjusting the on / off state of the PIN diodes, the width and length of the DC feed line, the size and position of the fan-shaped stubs, and the connection method of the DC feed line all affect the overall beam scanning results of the array, and these parameters need to be comprehensively optimized. Attached Figure Description

[0042] Figure 1 This is a flowchart of the process of the present invention.

[0043] Figure 2 This is a schematic diagram illustrating the arbitrary linear polarization implementation of the present invention.

[0044] Figure 3 This is a schematic diagram of the unit structure, the radiating patch layer, and the DC feeder layer of the present invention.

[0045] Figure 4 This is a schematic diagram of the antenna array arrangement of the present invention.

[0046] Figure 5 This is a diagram of the single-subarray structure of the present invention.

[0047] Figure 6 This is a schematic diagram of the three scanning angle encoding states of the present invention.

[0048] Figure 7 This is a diagram showing the 25GHz beam scanning results of the single-array of the present invention.

[0049] Figure 8 This is a diagram showing the 26GHz beam scanning results of the single-array of the present invention.

[0050] Figure 9 This is a diagram showing the 27GHz beam scanning results of the single-array of the present invention.

[0051] Figure 10 This is a schematic diagram of the maximum gain curve of the single-subarray scanning beam of the present invention.

[0052] Figure 11 This is a unit simulation design diagram.

[0053] Figure 12 The impedance curve for the unit simulation is shown.

[0054] Figure 13 This is a schematic diagram of the front of the array.

[0055] Figure 14 This is a schematic diagram of the back of the array.

[0056] Figure label:

[0057] 1. Unit radiating patch (surface-mount two PIN diodes in the same direction); 2. First dielectric layer (SH7136 substrate, dielectric constant 3.55, thickness 0.762mm); 3. Ground plane; 4. Second dielectric layer (SH7136 substrate, dielectric constant 3.55, thickness 0.254mm); 5. DC feed line layer (one end connected to the positive terminal, the other end connected to the negative terminal); 6. Array radiating patch layer; 7. Array DC feed line layer; 8. Metal backplate. Detailed Implementation

[0058] The present invention will now be described in further detail with reference to the accompanying drawings.

[0059] This invention discloses an arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface antenna array. This antenna array operates in the millimeter-wave band and can achieve arbitrary linear polarization. Its operation is as follows: Figure 1 As shown;

[0060] Step 1: The control board outputs a specific DC control signal to modulate the on / off state of the PIN diodes on the array surface. If the digital state of the cell is "1", the DC control signal is a voltage that enables the PIN diode to conduct. When the PIN diode is on, energy cannot radiate outward from the slot gap. Conversely, when the PIN diode is off, energy radiates outward from the slot gap.

[0061] Step 2: The metasurface units exhibit corresponding arrangement states. Since the DC feed lines of the array are connected in series in the X direction and connected to the control board, when the control board outputs a voltage that enables the PIN diodes to conduct, the PIN diodes conduct, and an entire column in that X direction exhibits a digital state "1"; conversely, an entire column exhibits a digital state "0". The metasurface units exhibit different digital state arrangement states.

[0062] Step 3: The surface impedance varies under different arrangement states. Based on the radiation principle of the leaky wave antenna and the reconfigurable holographic technology, the corresponding surface impedance of the array is set. The DC control signal is issued by the control board, passes through the DC feed line, through the metallized through hole, and finally arrives at both ends of the PIN diode of the unit radiating patch 1. The on / off state of the PIN diode is adjusted to make it present different digital states. In the digital state "1", the PIN diode is on and energy cannot be radiated outward from the slot. In the digital state "0", the PIN diode is off and energy is radiated outward from the slot.

[0063] Step 4: Scan the array to the corresponding angle. Conversely, reverse the process to set the encoding of the beam scanning state. The principle behind Step 4 is explained below.

[0064] Holographic technology principle: The microwave holographic process consists of two parts: interference recording and diffraction reconstruction. The surface impedance value Z(x) of the artificial impedance surface. t The wave Ψ formed by the current generated by the source antenna surf and the required radiation wave Ψ rad The pattern generated by the interference between the two is determined by equation (1):

[0065] Z(x t )=j[X+MRe(Ψ rad Ψ * surf (1)

[0066] Where x t Let X be a point on the impedance surface XOY, where X is the average surface impedance and M is the actual modulation depth. Assume the maximum and minimum impedance values ​​of the artificial impedance surface are Z0 and Z0, respectively. max and Z min ,but:

[0067] X=(Z max +Z min ) / twenty two)

[0068] M = (Z) max -Z min ) / twenty three)

[0069] The impedance of each unit at different scanning angles is determined according to equation (1), thereby determining the encoding state of the unit, i.e., whether the PIN diode on the unit is in the on or off state.

[0070] The maximum and minimum impedance values ​​Z in equation (2) max and Z min These correspond to the impedance values ​​of the PIN diode in both the on and off states, respectively. These two values ​​can be obtained through simulation measurement using electromagnetic simulation software after the unit size and structure are determined.

[0071] Unit structure description

[0072] a. Unit structure

[0073] First, design a rectangular radiating patch element operating in the corresponding frequency band. The element size is generally λ / 4 (λ = c / f, where λ is the wavelength of the corresponding frequency band). The size of the rectangular radiating patch 1 is smaller than the element size and needs to be determined based on the optimal simulation results. Then, slots are cut into the radiating patch according to the required linear polarization direction. For example... Figure 2 As shown. Taking a 45° linearly polarized unit as an example, its unit structure is as follows. Figure 3As shown in Table 1, the overall dimensions of the unit are as follows. The second dielectric layer 4 of the unit is made of SH7136 material, with a thickness of 1.016 mm, a dielectric constant of 3.55, and a loss tangent of 0.005. It is a three-layer structure.

[0074] The top layer is the unit radiation patch 1, which is a rectangular metal patch with a 45° slot along the diagonal and two PIN diodes (model MADP00907) placed in parallel in the middle; the middle layer is the metal ground plate 3; the bottom layer is the DC feed line layer 5, which introduces fan-shaped branches to isolate the radio frequency signals on the DC feed line. The left half of the DC feed line is connected to the positive terminal and the right half is connected to the negative terminal.

[0075] This structure achieves a ±45° dual-polarization array combination mode, which minimizes the overall size and allows for the expansion of the array's 2D directional scanning function by simply modifying the DC feed line.

[0076] To ensure optimal array radiation performance, the minimum number of PIN diodes is used, i.e., two PIN diodes per unit, thus minimizing costs. (The radiation performance of a single PIN diode array deteriorates, while the radiation performance of two or more PIN diodes is essentially the same).

[0077] like Figure 3 As shown in diagram a; ① is the unit radiating patch, its structure is a rectangular metal patch with a 45° slot along the diagonal (gap width is gap_x), allowing the RF signal to radiate along the 45° linear polarization direction; two PIN diodes (model MADP00907) are placed parallel to each other in the middle, and their conduction or cutoff is controlled by a DC control signal, so that the unit presents two digital states, "0" and "1". ② and ④ are dielectric layers made of SH7136 material, with thicknesses of 0.254mm and 0.762mm, respectively. ③ is a metal ground plane. ⑤ is a DC feed line layer, with fan-shaped branches introduced to isolate the RF signal on the DC feed line. The left half of the DC feed line is connected to the positive terminal, and the right half is connected to the negative terminal. Its overall function is to introduce a DC control signal to regulate the on / off state of the PIN diodes without affecting the RF signal.

[0078] like Figure 3 As shown in Figure b, the overall radiating patch layer structure consists of a rectangular metal patch of length Px with a 45° slot. Two PIN diodes are placed in parallel in the middle. Two metallized vias are symmetrically distributed about the slot gap, with a radius of via_r and positions dx and dy. They connect the unit radiating patch layer 1 and the DC feed line layer 5, and introduce a DC control signal to regulate the on / off state of the PIN diodes.

[0079] like Figure 3As shown in Figure c, the DC feeder layer 5 consists of two centrally symmetrical parts, connected to the positive and negative terminals of the DC signal, respectively. Each part of the DC feeder consists of three parts: a rectangular cross-section, a fan-shaped stub, and a circular pad. The fan-shaped stub is used to isolate the RF signal on the DC feeder and reduce RF signal loss. Its radius is Rc, its angle is rot, and its position is dc_l1. The rectangular cross-section has a width of dc_w and a length of Lx, and its function is to transmit DC control signals. The circular pad has a diameter of pad_r, is located on the rectangular cross-section, and connects to the metallized via. Its function is to provide a better tight connection between the metallized via and the DC feeder, so its diameter is slightly larger than that of the metallized via.

[0080] When both PIN diodes are simultaneously turned on (digital state 1) and simultaneously turned off (digital state 0), the impedances in the two states are 210Ω and 80Ω, respectively.

[0081] Table 1. Dimensional parameters (unit: mm)

[0082] Lx Px dx dy gap_x via_r Rc dc_w rot pad_r dc_l1 3 1.8 0.45 0.45 0.2 0.15 1.5 0.1 45 0.2 0.35

[0083] b. Array structure

[0084] To meet the requirements of mobile communication, this antenna array needs two subarrays with a 90° polarization difference to transmit signals (one subarray is 30° polarized, and the other is -60° polarized; only the direction of the slots needs to be changed, the overall array arrangement remains the same). Therefore, the antenna array is arranged as follows: Figure 4 As shown, the two subarrays employ +45° and -45° polarization respectively, and are placed in parallel, which effectively reduces the surface area. The more cells in the X and Y directions of the array, the greater the overall gain. Since all cells in the X direction share the same digital state, the array is equivalent to a linear array in the Y direction.

[0085] Homopolar subarray structure such as Figure 5 As shown, the number of elements in the Y direction of the single array is 16, and its DC power supply is cascaded (positive terminal connected to the control board, negative terminal grounded), and the entire row of PIN diodes is in the same state. The number of elements in the X direction is 38, and two 45° co-polarized arrays are placed in parallel. The overall size of the single board is 170mm × 150mm, and the overall cross-sectional height is 10mm.

[0086] The positive terminal of the DC feed line connects to the FPC connector, located on the back of the array. The FPC connector connects to the control board via a flexible flat cable, introducing DC control signals. The negative terminal connects to the ground plane 3 via a metallized through-hole. The control board outputs DC control signals to regulate the metasurface encoding state, thereby enabling the array beam to scan at different angles. Some angle encoding states are as follows: Figure 6 As shown.

[0087] c. Radio frequency port

[0088] Write a corresponding MATLAB program based on formula (1), input the required scanning angle, and it can output the digital encoding status of the corresponding 1-38 column units - "0" or "1".

[0089] Based on the principle of holographic technology, given the far-field pattern corresponding to the required scanning angle, the actual required impedance value at different positions of the array can be calculated. Then, each unit is digitally quantized – when the actual impedance value of the unit is greater than the average surface impedance, it is in digital state "1", and when it is less than the average surface impedance, it is in digital state "0".

[0090] The array back structure is as follows Figure 14 As shown, the single-subarray RF feed port uses two ports of the single subarray, and a 1-to-2 power divider is added to connect these two ports.

[0091] The front structure of the array is as follows Figure 13 As shown, tilting plates are added to achieve better impedance matching. The widest part of each tilting plate is 12mm long, equivalent to four elements. The two RF ports of the subarray can be used simultaneously as both transmit and receive ports.

[0092] Through such Figure 1 The design flow shown first involves designing the unit cells for the corresponding frequency band and the required linear polarization direction; then, electromagnetic simulation software is used to set up... Figure 11 The boundary conditions and ports shown are as follows: an air box is added around the element, with its size in the X and Y directions the same as the element size, and its vertical height in the Z direction exceeding the element by λ / 4. The top surface of the air box is set as the 'Floquet Port' port condition, and two pairs of master / slave boundary conditions are set around it (Master1 and Slave1, Master2 and Slave2, corresponding to each other).

[0093] The impedance Z of the PIN diode in both on and off states was measured and calculated. on and Z off (like Figure 12 (as shown); then, according to equation (1), the encoding state of each element at each position in the array (whether the PIN tube of the element is in the on or off state) is calculated under different scanning conditions. By outputting a DC control signal from the control board, the encoding state of the element can be adjusted, thus realizing the function of millimeter-wave beam scanning. Through this design method and the three-layer structure of the element (radiating patch, ground plane and DC feed line layer), the design of an arbitrary linearly polarized millimeter-wave reconfigurable leaky antenna array can be realized.

[0094] The array DC feed line adopts a series connection of positive (negative) poles in columns, which greatly simplifies the design of the DC feed layer and the overall structure, and facilitates large-scale industrial production and processing.

[0095] The beam scanning results of the single array are as follows Figures 7-10 As shown, the present invention can achieve wide-angle beam scanning of -50° to +50° in the entire frequency band of 25GHz to 27GHz by adjusting the metasurface coding state, with a maximum gain of 18dB and cross-polarization greater than 15dB.

Claims

1. An antenna array, characterized in that, It includes two subarrays, each composed of an arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface antenna element structure arranged along the X and Y directions, and the two subarrays are symmetrical about the X-axis; the arbitrary linearly polarized millimeter-wave reconfigurable holographic metasurface antenna element structure in each subarray has a straight through slot in the same direction; and the polarization of the two subarrays differs by 90°. In each subarray, the DC feed line is cascaded, with the positive terminal connected to the control board and the negative terminal grounded. If the Y direction is defined as a column, then the entire column of PIN diodes will have the same state. A reconfigurable holographic metasurface antenna unit structure for arbitrary linear polarization millimeter waves includes, from top to bottom, a unit radiating patch layer (1), a first dielectric layer (2), a metal plate (3), a second dielectric layer (4), and a DC feed line layer (5). The unit radiation patch layer (1) is square, with straight through slots on its surface to form slot gaps. The two parts formed by the slots are connected by PIN diodes across the slot gaps, and linear polarization in the corresponding direction is achieved according to the slot direction.

2. The antenna array according to claim 1, characterized in that, One or two PIN diodes are disposed on the slot gap of the unit radiating patch layer (1). When there are two, they have the same polarity. Two metallized through holes are symmetrically distributed along the slot gap, connecting the unit radiating patch layer (1) and the DC feed line layer (5). A specific DC control signal is output through the control board to modulate the on / off state of the PIN diodes on the array surface. If the digital state of the unit is "1", the DC control signal is a voltage that can turn on the PIN diode. The DC control signal outputs a voltage that can turn on the PIN diode. When the PIN diode is on, energy cannot be radiated outward from the slot gap. Conversely, when the PIN diode is off, energy is radiated outward from the slot gap.

3. The antenna array according to claim 1, characterized in that, The DC feeder layer (5) consists of two centrally symmetrical parts, namely an upper part and a lower part. The upper part is connected to the DC control signal, and the lower part is cascaded together and connected to the metal plate (3) of the middle layer through metallized through holes.

4. The antenna array according to claim 3, characterized in that, Each section of the DC feeder consists of three parts: a rectangular cross-section, a fan-shaped stub, and a circular pad. The upper part of the circular pad is located on the rectangular cross-section and is connected to the metallized via, which is used to provide a tight connection between the metallized via and the DC feed line. The fan-shaped stub is connected to the rectangular cross-section and is located on the rectangular cross-section. The fan-shaped stub is used to isolate the radio frequency signal on the DC feed line and reduce the loss of the radio frequency signal. The rectangular cross-section is for transmitting DC control signals; The lower part is obtained by rotating the upper part around the center of the unit.

5. The antenna array according to claim 1, characterized in that, The first dielectric layer (2), the metal plate (3), the second dielectric layer (4) and the DC feed line layer (5) are all square with a side length of λ / 4; the side length of the unit radiation patch layer (1) is λ / 12 to λ / 8. The unit size of the holographic metasurface antenna unit structure is λ / 4, where λ = c / f is the wavelength of the required antenna operating frequency band, f is the frequency, and c is the speed of light in vacuum, 3x10^8m / s. The size of the unit radiation patch layer (1) is 1 / 3 to 1 / 2 of the unit size of the holographic metasurface antenna unit structure. The antenna's energy is radiated outward from the slots in the unit radiating patch layer (1), and different slot directions can achieve corresponding linear polarization angles.

6. The antenna array according to claim 1, characterized in that, The positive terminal of the DC feed line is connected to the FPC connector, which is located on the back of the array. It is used to connect to the control board via a flexible flat cable and introduce DC control signals. The negative terminal is connected to the metal plate (3) through a metallized through-hole. The control board outputs DC control signals to regulate the metasurface encoding state, thereby enabling the array beam to scan to different angles.

7. The antenna array according to claim 1, characterized in that, The single-subarray RF feed port of the rear structure of the antenna array adopts two ports of the single subarray, and the two ports are connected to the power divider; The antenna array employs a tilting plate for impedance matching at the RF feed port of its front structure.

8. A method of using the antenna array according to any one of claims 1-7, characterized in that, Includes the following steps; Step 1: The control board outputs a specific DC control signal to modulate the on / off state of the PIN diodes on the array surface; if the digital state of the cell is "1", then the DC control signal is a voltage that can turn on the PIN diode; the DC control signal outputs a voltage that can turn on the PIN diode, the PIN diode is on, and energy cannot be radiated outward from the slot gap; Conversely, when the PIN diode is in the off state, energy radiates outward from the slot gap; Step 2: When the control board outputs a voltage that enables the PIN diode to conduct, the PIN diode conducts, and an entire column in the Y direction displays the digital state "1"; conversely, an entire column displays the digital state "0", and the metasurface units exhibit different digital state arrangements. Step 3: The DC control signal is sent by the control board, passes through the DC feed line, passes through the metallized through hole, and finally arrives at both ends of the PIN diode of the unit radiation patch (1). The on and off states of the PIN diode are adjusted to make it present different digital states. When the digital state is "1", the PIN diode is turned on and energy cannot be radiated outward from the slot gap. In digital state "0", the PIN diode is in the off state, and energy radiates outward from the slot gap; Step 4: Scan the array to the corresponding angle, and conversely, set the encoding of the beam scanning state in reverse in this way.

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