A millimeter-wave adaptive wireless power transmission system and method based on a liquid crystal holographic phased array antenna

Abstract

This invention discloses a millimeter-wave adaptive wireless power transmission system and method based on a liquid crystal holographic phased array antenna, belonging to the field of microwave wireless power transmission technology. The system includes a transmitter and a receiver. The transmitter includes a liquid crystal holographic phased array, a bias circuit, an FPGA control circuit, several positioning antennas, and a phase detector. The receiver includes a receiver antenna and a rectifier circuit module. The liquid crystal holographic phased array antenna includes a metal patch array, liquid crystal, a ground plane and dielectric substrate with etched slot arrays, a bias network, and a feed structure. The voltage control circuit is implemented by an FPGA and connected to the radiating element through the bias network. The antenna feed uses a coaxial probe to feed the generated radio frequency signal. This invention determines the target location based on a time-domain positioning algorithm and achieves energy focusing at the target location through holographic principles, solving the problems of high cost, large profile, and large size in wireless power transmission systems, ultimately realizing adaptive wireless power transmission in the millimeter-wave band.

Description

Technical Field

[0001] This invention belongs to the field of microwave wireless power transmission technology, specifically relating to a millimeter-wave adaptive wireless power transmission system and method based on a liquid crystal holographic phased array antenna. Background Technology

[0002] With the development of science and technology, electronic devices have become an indispensable part of people's lives. In recent years, due to the rapid development of IoT technology and wearable electronics technology, a large number of low- and medium-power wireless sensors and portable mobile devices have appeared in people's living environment. Currently, most of these electronic devices are still powered by batteries. However, battery power requires regular replacement, which undoubtedly increases costs. In addition, the size and weight of batteries also limit the portability and miniaturization of electronic devices. Therefore, wireless power transmission has been proposed to address these issues. Wireless power transmission can supply power to electronic devices without physical contact, and it has significant advantages over traditional methods for powering devices operating in harsh and complex environments, such as implantable devices and underwater sensors. Among all wireless power transmission methods, the most ideal solution is currently microwave power transmission. Compared with coil coupling, microwave wireless power transmission has a longer transmission distance, achieving wireless power transmission from meters to kilometers. Furthermore, compared with laser wireless power transmission, it has higher transmission efficiency and stronger obstacle penetration capability.

[0003] Currently, research on microwave wireless power transmission mainly focuses on the centimeter wave band, commonly around 2.4 GHz and 5.8 GHz. The microwave energy transmitter mainly uses phased arrays. Phased array antennas can precisely control the beam direction and achieve energy focusing. However, their feeding network is complex and requires a large number of phase shifters and other equipment, resulting in high costs. Furthermore, the spacing between their elements is usually half a wavelength, making the antenna size very large.

[0004] A Chinese patent application entitled "A Space Millimeter-Wave Wireless Power Transmission System" discloses a millimeter-wave wireless power transmission system that uses a high-transmittance topology material to design the millimeter-wave transmitting antenna, achieving far-field focusing. However, the entire system has a complex circuit design and requires many battery packs, resulting in a large system size and high cost. Other existing wireless power transmission systems mostly require complex feeder networks and various power amplifiers, leading to high cost, large size, and high energy loss, and most cannot achieve adaptive power transmission functionality. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a millimeter-wave adaptive wireless power transmission system and method based on a liquid crystal holographic phased array antenna. By using a liquid crystal holographic phased array antenna, combined with the holographic principle, and utilizing electrically tunable liquid crystal material, the invention solves the problems of high cost, complex structure, low efficiency, high profile, and inability to adapt in wireless power transmission systems.

[0006] The technical problem addressed by this invention is solved as follows:

[0007] A millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna, comprising a transmitter and a receiver;

[0008] The transmitting end includes a liquid crystal holographic phased array, a bias circuit, an FPGA control circuit, several positioning antennas, and a phase detector; the receiving end includes a receiving antenna and a rectifier circuit module.

[0009] The liquid crystal holographic phased array includes an upper dielectric substrate 1, a first metal layer 2, a sealing frame 3, a liquid crystal layer 4, a second metal layer 5, a lower dielectric substrate 6, a microwave absorbing material 7, a metal ground plane 8, and an RF coaxial connector 9.

[0010] The first metal layer 2 is located on the lower surface of the upper dielectric substrate 1 and is composed of M×N rectangular metal patches 201 arranged in a two-dimensional periodic pattern, where M and N are both positive integers greater than or equal to 2; the second metal layer 5 is located on the upper surface of the lower dielectric substrate 6 and is formed by etching M×N rectangular slots 501 arranged in a two-dimensional periodic pattern on the basis of fully covering the upper surface of the lower dielectric substrate 6; the center positions of the rectangular metal patches 201 and the rectangular slots 501 correspond one-to-one; the side length of the rectangular metal patches 201 is greater than the length of the rectangular slots 501;

[0011] The liquid crystal layer 4 is filled between the lower surface of the upper dielectric substrate 1 and the upper surface of the lower dielectric substrate 6; a sealing frame 3 is provided around the perimeter of the liquid crystal layer 4, and the sealing frame 3, the upper dielectric substrate 1 and the lower dielectric substrate 6 are bonded together to form a sealed liquid crystal cell to ensure that the liquid crystal layer 4 does not overflow.

[0012] The lower dielectric substrate 6 has a wave-absorbing material 7 around its perimeter, and a metal ground plate 8 is located on the lower surface of the lower dielectric substrate 6. A coaxial connector 9 is located at the bottom center of the metal ground plate 8, and the outer metal wall is connected to the metal layer 8. The inner core 902 passes through the metal layer 8 and the lower dielectric substrate 6 and is connected to the second metal layer 5.

[0013] The bias network includes bias lines and pins. Each rectangular metal patch 201 in the first metal layer 2 is connected to a corresponding bias line and pin. The FPGA control circuit outputs voltage to each pin through the wave control board, which is then applied to the corresponding metal patch 201 to control the bias voltage of the corresponding metal patch 201, thereby realizing the regulation of the dielectric constant of the liquid crystal and controlling the switching state of the radiating unit corresponding to each rectangular metal patch 201.

[0014] The receiving antenna transmits a power request signal into space, and each positioning antenna receives the power request signal and sends it to a phase detector. The phase detector performs phase detection on the power request signal received by each positioning antenna and extracts the phase information. The receiving end is located using the phase information of the power request signal received by each positioning antenna. The FPGA control circuit determines the holographic pattern based on the positioning result, determines the switching state of each radiating element, and adjusts the liquid crystal dielectric constant of each radiating element through a bias network, thereby controlling the switching state of each radiating element. The liquid crystal holographic phased array radiates energy signals into space, and the receiving antenna receives the energy signals and sends them to the rectifier circuit module. The rectifier circuit module converts the received radio frequency signal into a DC signal for energy storage.

[0015] Furthermore, the rectangular metal patch 201 and the rectangular gap 501 corresponding to the center position, together with the upper dielectric substrate 1, the liquid crystal layer 4, the second metal layer 5, the lower dielectric substrate 6 and the metal ground plate 8 at the corresponding positions, constitute a radiating unit.

[0016] When an RF signal is fed into the coaxial connector 9 port, an outward radial wave is generated with the second metal layer 5 and the metal ground plane 8 as the upper and lower boundaries and the inner core 902 as the axis. The wave radiated by the inner core 902 of the coaxial connector 9 is radiated into space in the form of leakage waves during propagation. The electromagnetic wave is coupled into the liquid crystal layer 4 through the rectangular slit 501 and then radiated out by the rectangular metal patch 201. After the liquid crystal is aligned, the liquid crystal molecules are aligned when no bias voltage is applied, and the liquid crystal material has the minimum or maximum dielectric constant. When a bias voltage is applied to the metal patch 201, the dielectric constant of the liquid crystal material can be changed, thereby adjusting the radiation characteristics of the radiating unit. The electromagnetic waves that are not completely leaked are absorbed by the absorbing material at the edges of the lower dielectric substrate.

[0017] Furthermore, the receiving antenna adopts an array antenna structure or a single antenna, and the rectifier circuit adopts a half-wave rectifier circuit or a full-wave rectifier circuit.

[0018] Furthermore, the positioning antenna is an active single antenna, employing a dipole antenna or a microstrip patch antenna.

[0019] Furthermore, the upper dielectric substrate 1 and the lower dielectric substrate 6 in the liquid crystal holographic phased array are made of glass.

[0020] Utilizing the aforementioned millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna, this invention also provides a millimeter-wave adaptive wireless power transmission method based on a liquid crystal holographic phased array antenna, comprising the following steps:

[0021] Step 1. The receiving antenna transmits a power request signal omnidirectionally into space;

[0022] Step 2. Each positioning antenna receives the power request signal in space and sends it to the phase detector; the phase detector mixes and low-pass filters the power request signal received by each positioning antenna with the local oscillator signal to complete the phase extraction of the power request signal received by each positioning antenna.

[0023] Step 3. Use the phase of the power request signal received by each positioning antenna to locate the position of the receiving end;

[0024] Step 4. The liquid crystal holographic phased array is located in the xoy plane, and the short side of the rectangular metal patch 201 is parallel to the x-axis; the receiver in space is equivalent to a point source, and the target wave is the Green's function in space when the point source is focused:

[0025]

[0026] Where, ψ obj To generate the field strength distribution of a point source focused at the receiving end, j is the imaginary part. The position of the receiving end in the xoy plane. The position of the liquid crystal holographic phased array is given by ||, where || represents the modulus.

[0027] The reference wave propagates outwards in the form of a cylindrical wave:

[0028]

[0029] Where, ψ ref For the field distribution of the reference wave, k g Let x and y be the propagation constant of the reference wave in the liquid crystal holographic phased array, and let x and y be the abscissa and ordinate of any point in the liquid crystal holographic phased array in the xoy plane.

[0030] Cylindrical waves are represented by the Hankel function, and reference waves with different polarization directions are represented as follows:

[0031]

[0032] in, This represents the first kind of Hankel function of order 0;

[0033] Step 5. Multiply the target wave expression and the reference wave expression by their conjugates to obtain the holographic pattern M:

[0034]

[0035] The superscript * indicates taking the conjugate;

[0036] For the y-polarization direction, the phase difference between the two parts of the reference wave propagating in the vertical direction is 180° to correct for the holographic pattern, resulting in the following corrected holographic pattern:

[0037]

[0038] For the x-polarization direction, a 180° phase difference between the two parts of the reference wave propagating in the left and right directions is used for correction, resulting in the corrected holographic pattern:

[0039]

[0040] The real part of the holographic sample is extracted and normalized to obtain the normalized holographic sample value M at any point in the liquid crystal holographic phased array. Normal for:

[0041]

[0042] Where Re denotes the real part, Re(M) max and Re(M) min These represent the maximum and minimum values ​​of the holographic pattern at each point in the liquid crystal holographic phased array, respectively.

[0043] If the normalized holographic pattern value M Normal If the value is greater than the set threshold 'a', the corresponding radiating element is in the "on" state; if the normalized holographic pattern value M... Normal If the value is less than the set threshold 'a', the corresponding radiating element is in the "off" state. The FPGA control circuit regulates the liquid crystal dielectric constant of each radiating element through the bias network, thereby controlling the switching state of each radiating element. The reference wave is used as the excitation source to excite the liquid crystal holographic phased array, which radiates energy signals into space to achieve adaptive focusing at the receiving end.

[0044] Step 6. The receiving antenna receives the energy signal and sends it to the rectifier circuit module. The rectifier circuit module converts the received radio frequency signal into a DC signal for energy storage.

[0045] Furthermore, in step 2, the power request signal received by each positioning antenna is at the same frequency as the local oscillator signal, and the power request signal received by the positioning antenna is denoted as... Let the local oscillator signal be denoted as S2 = cos(wt), then the mixed signal S3 is:

[0046]

[0047] Where w is the angular frequency of the power request signal received by the positioning antenna, and t is time. The phase of the signal received by the nth positioning antenna;

[0048] Low-pass filtering is performed on signal S3 to obtain This completes the phase information of the signals received by each positioning antenna. Extraction.

[0049] Furthermore, in step 3, Where k0 is the propagation constant of electromagnetic waves in free space, l n Let l be the distance from the receiver to the nth positioning antenna; with each positioning antenna as the center of the sphere, the corresponding distance l is... n The location of the receiver is the common intersection of all the spheres, which serve as the radius.

[0050] Furthermore, the dielectric constants of the liquid crystal corresponding to the "on" and "off" states of the radiating unit are 3.8 and 2.7, respectively, and the threshold value a is set to range from 0.5 to 0.9.

[0051] The beneficial effects of this invention are:

[0052] The millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna described in this invention, compared with existing wireless power transmission systems, operates in the millimeter-wave frequency band, has a smaller antenna size, and does not require a large number of active devices such as phase shifters and power amplifiers. It has the advantages of compact structure, simple power supply, low cost and low weight. The method described in this invention combines positioning algorithms and holographic principles to achieve spatial adaptive wireless power transmission. Attached Figure Description

[0053] Figure 1 This is a three-dimensional structural schematic diagram of the liquid crystal holographic phased array in the energy transmission system described in this invention;

[0054] Figure 2 This is a top view of the liquid crystal holographic phased array in the energy transmission system described in this invention;

[0055] Figure 3 This is a schematic diagram of the energy transfer method described in this invention;

[0056] Figure 4 This is a schematic diagram of the structural framework of the energy transmission system described in this invention. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0058] This embodiment provides a millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna, and its structural framework is shown in the schematic diagram below. Figure 4 As shown, it includes the transmitter and receiver;

[0059] The transmitting end includes a liquid crystal holographic phased array, a bias circuit, an FPGA control circuit, several positioning antennas, and a phase detector; the receiving end includes a receiving antenna and a rectifier circuit module.

[0060] A schematic diagram of the three-dimensional structure of a liquid crystal holographic phased array is shown below. Figure 1 As shown, the top view is as follows Figure 2 As shown, it includes an upper dielectric substrate 1, a first metal layer 2, a sealing frame 3, a liquid crystal layer 4, a second metal layer 5, a lower dielectric substrate 6, a microwave absorbing material 7, a metal ground plane 8, and an RF coaxial connector 9.

[0061] The first metal layer 2 is located on the lower surface of the upper dielectric substrate 1 and is composed of M×N rectangular metal patches 201 arranged in a two-dimensional periodic pattern, where M and N are both positive integers greater than or equal to 2. The second metal layer 5 is located on the upper surface of the lower dielectric substrate 6 and is formed by etching M×N rectangular slots 501 arranged in a two-dimensional periodic pattern on the basis of fully covering the upper surface of the lower dielectric substrate 6. The center positions of the rectangular metal patches 201 and the rectangular slots 501 correspond one-to-one. The side length of the rectangular metal patches 201 is greater than the length of the rectangular slots 501 to ensure that the rectangular metal patches 201 can cover the entire rectangular slots 501.

[0062] The liquid crystal layer 4 is filled between the lower surface of the upper dielectric substrate 1 and the upper surface of the lower dielectric substrate 6; a sealing frame 3 is provided around the perimeter of the liquid crystal layer 4, and the sealing frame 3, the upper dielectric substrate 1 and the lower dielectric substrate 6 are bonded together to form a sealed liquid crystal cell to ensure that the liquid crystal layer 4 does not overflow.

[0063] The lower dielectric substrate 6 has a wave-absorbing material 7 around its perimeter, and a metal ground plate 8 is located on the lower surface of the lower dielectric substrate 6. A coaxial connector 9 is located at the bottom center of the metal ground plate 8, and the outer metal wall is connected to the metal layer 8. The inner core 902 passes through the metal layer 8 and the lower dielectric substrate 6 and is connected to the second metal layer 5. By reasonably arranging the rectangular gaps 501 of the second metal layer 5, there are no rectangular gaps 501 arranged at the center of the second metal layer 5.

[0064] The rectangular metal patch 201 and the rectangular gap 501 at the center position, together with the upper dielectric substrate 1, the liquid crystal layer 4, the second metal layer 5, the lower dielectric substrate 6 and the metal ground plate 8 at the corresponding positions, constitute a radiating unit.

[0065] When an RF signal is fed into the coaxial connector 9 port, an outward radial wave is generated with the second metal layer 5 and the metal ground plane 8 as the upper and lower boundaries and the inner core 902 as the axis. During propagation, the wave radiated by the inner core 902 of the coaxial connector 9 is radiated into space in the form of a leakage wave; the electromagnetic wave is coupled into the liquid crystal layer 4 through the rectangular slit 501, and then radiated out by the rectangular metal patch 201; the liquid crystal is aligned so that the liquid crystal molecules are aligned when no bias voltage is applied, and the liquid crystal material has a minimum or maximum dielectric constant; when a bias voltage is applied to the metal patch 201, the dielectric constant of the liquid crystal material can be changed, thereby adjusting the radiation characteristics of the radiating unit; the electromagnetic wave that is not completely leaked is absorbed by the wave-absorbing material at the edges of the lower dielectric substrate to prevent reflection and affect the purity of the traveling wave.

[0066] The bias network includes bias lines and pins. Each rectangular metal patch 201 in the first metal layer 2 is connected to a corresponding bias line and pin. The FPGA control circuit outputs voltage to each pin through the wave control board, and then applies it to the corresponding metal patch 201 to control the bias voltage of the corresponding metal patch 201, thereby realizing the regulation of the dielectric constant of the liquid crystal, and then controlling the switching state of each radiating unit to achieve binary regulation.

[0067] The receiving antenna transmits a power request signal into space, and each positioning antenna receives the power request signal and sends it to a phase detector. The phase detector performs phase detection on the power request signal received by each positioning antenna and extracts the phase information. The receiving end is located using the phase information of the power request signal received by each positioning antenna. The FPGA control circuit determines the holographic pattern based on the positioning result, determines the switching state of each radiating element, and adjusts the liquid crystal dielectric constant of each radiating element through a bias network, thereby controlling the switching state of each radiating element. The liquid crystal holographic phased array radiates energy signals into space, and the receiving antenna receives the energy signals and sends them to the rectifier circuit module. The rectifier circuit module converts the received radio frequency signal into a DC signal for energy storage.

[0068] The receiving antenna adopts an array antenna structure or a single antenna, such as a standard gain horn antenna with an input waveguide of BJ-260; the rectifier circuit adopts a half-wave rectifier circuit or a full-wave rectifier circuit.

[0069] The positioning antenna is an active single antenna such as a dipole antenna or a microstrip patch antenna.

[0070] The upper dielectric substrate 1 and the lower dielectric substrate 6 in the liquid crystal holographic phased array are made of glass or other materials.

[0071] Utilizing the aforementioned millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna, this embodiment also provides a millimeter-wave adaptive wireless power transmission method based on a liquid crystal holographic phased array antenna, the flowchart of which is shown below. Figure 3As shown, it includes the following steps:

[0072] Step 1. The receiving antenna transmits a power request signal omnidirectionally into space;

[0073] Step 2. Each positioning antenna receives the power request signal in space and sends it to the phase detector; the phase detector mixes and low-pass filters the power request signal received by each positioning antenna with the local oscillator signal to complete the phase extraction of the power request signal received by each positioning antenna.

[0074] The power transmission request signal received by each positioning antenna is at the same frequency as the local oscillator signal, and the power transmission request signal received by the positioning antenna is denoted as... Let the local oscillator signal be denoted as S2 = cos(wt), then the mixed signal S3 is:

[0075]

[0076] Where w is the angular frequency of the power request signal received by the positioning antenna, and t is time. The phase of the signal received by the nth positioning antenna;

[0077] Low-pass filtering is performed on signal S3 to obtain This completes the phase information of the signals received by each positioning antenna. Extraction;

[0078] Step 3. Because Where k0 is the propagation constant of electromagnetic waves in free space, l n Let l be the distance from the receiver to the nth positioning antenna; therefore, the distance l corresponding to each positioning antenna as the center of the sphere can be obtained. n The location of the receiver is the common intersection of all the spheres, which serve as the radius.

[0079] Step 4. The liquid crystal holographic phased array is located in the xoy plane, and the short side of the rectangular metal patch 201 is parallel to the x-axis; the receiver in space can be equivalent to a point source. According to electromagnetic theory, when the point source is focused, the target wave is the Green's function in space:

[0080]

[0081] Where, ψ obj To generate the field strength distribution of a point source focused at the receiving end, j is the imaginary part. The position of the receiving end in the xoy plane. The position of the liquid crystal holographic phased array is given by ||, where || represents the modulus.

[0082] A coaxial probe is used as the feed source, and the reference wave propagates in all directions in the form of a cylindrical wave:

[0083]

[0084] Where, ψ ref For the field distribution of the reference wave, k g Let x and y be the propagation constant of the reference wave in the liquid crystal holographic phased array, and let x and y be the abscissa and ordinate of any point in the liquid crystal holographic phased array in the xoy plane.

[0085] According to electromagnetic theory, cylindrical waves are represented by the Hankel function, and can be further generalized to represent them according to different polarization directions of the reference wave:

[0086]

[0087] in, This represents the first kind of Hankel function of order 0;

[0088] Step 5. Multiply the target wave expression and the reference wave expression by their conjugates to obtain the holographic pattern M:

[0089]

[0090] The superscript * indicates taking the conjugate;

[0091] Liquid crystal holographic phased arrays employ center feeding. A phase difference exists between the forward and backward propagation of the reference wave, causing a beam center dip. Therefore, for the y-polarization direction, the two parts of the reference wave propagating in the vertical direction need to be 180° out of phase to correct this, resulting in the corrected holographic pattern:

[0092]

[0093] For the x-polarization direction, the phase difference between the two parts of the reference wave propagating in the left and right directions needs to be 180°, resulting in the corrected holographic pattern as follows:

[0094]

[0095] The real part of the holographic sample is extracted and normalized to obtain the normalized holographic sample value M at any point in the liquid crystal holographic phased array. Normal for:

[0096]

[0097] Where Re denotes the real part, Re(M) max and Re(M) min These represent the maximum and minimum values ​​of the holographic pattern at each point in the liquid crystal holographic phased array, respectively.

[0098] If the normalized holographic pattern value M NormalIf the value is greater than the set threshold 'a', the corresponding radiating element is in the "on" state; if the normalized holographic pattern value M... Normal If the value is less than the set threshold 'a', the corresponding radiating element is in the "off" state. The FPGA control circuit regulates the liquid crystal dielectric constant of each radiating element through the bias network, thereby controlling the switching state of each radiating element. The reference wave is used as the excitation source to excite the liquid crystal holographic phased array, which radiates energy signals into space to achieve adaptive focusing at the receiving end.

[0099] In this embodiment, the liquid crystal dielectric constants corresponding to the "on" state and the "off" state are 3.8 and 2.7, respectively, and the threshold value a is set to a range of 0.5 to 0.9.

[0100] Step 6. The receiving antenna receives the energy signal and sends it to the rectifier circuit module. The rectifier circuit module converts the received radio frequency signal into a DC signal for energy storage.

[0101] Since holography is an analytical method, it can be used to achieve high-precision spatial point focusing, meeting the needs of real-time control. Furthermore, holography is also suitable for focusing energy transmission to multiple targets; as the electromagnetic superposition principle shows, it is only necessary to replace the target wave with a superimposed wave formed when multiple targets exist simultaneously.

[0102] The present invention has been described above with reference to the accompanying drawings. However, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna, characterized in that, Includes the transmitter and receiver; The transmitting end includes a liquid crystal holographic phased array, a bias circuit, an FPGA control circuit, several positioning antennas, and a phase detector; the receiving end includes a receiving antenna and a rectifier circuit module. The liquid crystal holographic phased array includes an upper dielectric substrate (1), a first metal layer (2), a sealing frame (3), a liquid crystal layer (4), a second metal layer (5), a lower dielectric substrate (6), a wave-absorbing material (7), a metal ground plane (8), and an RF coaxial connector (9). The first metal layer (2) is located on the lower surface of the upper dielectric substrate (1), and is formed by... The substrate consists of rectangular metal patches (201) arranged in a two-dimensional periodic pattern, where M and N are both positive integers greater than or equal to 2; the second metal layer (5) is located on the upper surface of the lower dielectric substrate (6), and the second metal layer (5) is etched with [missing information] on the basis of fully covering the upper surface of the lower dielectric substrate (6). A rectangular slot (501) arranged in a two-dimensional periodic pattern; the center positions of the rectangular metal patch (201) and the rectangular slot (501) correspond one-to-one; the side length of the rectangular metal patch (201) is greater than the length of the rectangular slot (501); The liquid crystal layer (4) is filled between the lower surface of the upper dielectric substrate (1) and the upper surface of the lower dielectric substrate (6); a sealing frame (3) is provided around the perimeter of the liquid crystal layer (4), and the sealing frame (3), the upper dielectric substrate (1) and the lower dielectric substrate (6) are bonded together to form a sealed liquid crystal cell to ensure that the liquid crystal layer (4) will not overflow. The lower dielectric substrate (6) is provided with a wave-absorbing material (7) around its perimeter, and a metal floor (8) is located on the lower surface of the lower dielectric substrate (6); a coaxial connector (9) is located at the bottom center of the metal floor (8), the outer metal wall is connected to the metal floor (8), and the inner core (902) passes through the metal floor (8) and the lower dielectric substrate (6) to connect to the second metal layer (5); The bias network includes bias lines and pins. Each rectangular metal patch (201) in the first metal layer (2) is connected to a corresponding bias line and pin. The FPGA control circuit outputs voltage to each pin through the wave control board, and then applies it to the corresponding metal patch (201) to control the bias voltage of the corresponding metal patch (201), thereby realizing the regulation of the dielectric constant of the liquid crystal, and then controlling the switching state of the radiation unit corresponding to each rectangular metal patch (201). The receiving antenna transmits a power request signal into space, and each positioning antenna receives the power request signal and sends it to the phase detector. The phase detector performs phase detection on the power request signal received by each positioning antenna and extracts the phase information. The phase information of the power request signal received by each positioning antenna is used to locate the receiving end. The FPGA control circuit determines the holographic pattern based on the positioning result, determines the switching state of each radiating element, and adjusts the liquid crystal dielectric constant of each radiating element through the bias network, thereby controlling the switching state of each radiating element. The liquid crystal holographic phased array radiates energy signals into space. The receiving antenna receives the energy signals and sends them to the rectifier circuit module. The rectifier circuit module converts the received radio frequency signals into DC signals for energy storage.

2. The millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna according to claim 1, characterized in that, The rectangular metal patch (201) and rectangular slit (501) at the center position, together with the upper dielectric substrate (1), liquid crystal layer (4), second metal layer (5), lower dielectric substrate (6) and metal ground (8) at the corresponding positions, constitute a radiating unit; When an RF signal is fed into the port of the coaxial connector (9), an outward radial wave is generated with the second metal layer (5) and the metal ground plane (8) as the upper and lower boundaries and the inner core (902) as the axis. The wave radiated by the inner core (902) of the coaxial connector (9) is radiated into space in the form of leakage wave during propagation. The electromagnetic wave is coupled into the liquid crystal layer (4) through the rectangular slit (501) and then radiated out by the rectangular metal patch (201). After the liquid crystal is aligned, the liquid crystal molecules are aligned when no bias voltage is applied, and the liquid crystal material has the minimum or maximum dielectric constant. When a bias voltage is applied to the metal patch (201), the dielectric constant of the liquid crystal material can be changed, thereby adjusting the radiation characteristics of the radiating unit. The electromagnetic waves that are not completely leaked are absorbed by the absorbing material at the edges of the lower dielectric substrate.

3. The millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna according to claim 1, characterized in that, The receiving antenna adopts an array antenna structure or a single antenna, and the rectifier circuit adopts a half-wave rectifier circuit or a full-wave rectifier circuit.

4. The millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna according to claim 1, characterized in that, The positioning antenna is an active single antenna, employing either a dipole antenna or a microstrip patch antenna.

5. The millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna according to claim 1, characterized in that, The upper dielectric substrate (1) and the lower dielectric substrate (6) in the liquid crystal holographic phased array are made of glass.

6. A millimeter-wave adaptive wireless power transmission method based on a liquid crystal holographic phased array antenna, implemented using the millimeter-wave adaptive wireless power transmission system based on a liquid crystal holographic phased array antenna as claimed in claim 1, comprising the following steps: Step 1. The receiving antenna transmits a power request signal omnidirectionally into space; Step 2. Each positioning antenna receives the power request signal in space and sends it to the phase detector; the phase detector mixes and low-pass filters the power request signal received by each positioning antenna with the local oscillator signal to complete the phase extraction of the power request signal received by each positioning antenna. Step 3. Use the phase of the power request signal received by each positioning antenna to locate the position of the receiving end; Step 4. The liquid crystal holographic phased array is located in the xoy plane, and the short side of the rectangular metal patch (201) is parallel to the x-axis; the receiver in space is equivalent to a point source, and the target wave is the Green's function in space when the point source is focused: in, To generate the field strength distribution of a point source focused at the receiving end, j is the imaginary part. Let be the propagation constant of electromagnetic waves in free space. The position of the receiving end in the xoy plane. The position of the liquid crystal holographic phased array. Indicates modulo; The reference wave propagates outwards in the form of a cylindrical wave: in, For the field distribution of the reference wave, Let x and y be the propagation constant of the reference wave in the liquid crystal holographic phased array, and let x and y be the abscissa and ordinate of any point in the liquid crystal holographic phased array in the xoy plane. Cylindrical waves are represented by the Hankel function, and reference waves with different polarization directions are represented as follows: in, This represents the first kind of Hankel function of order 0. The phase of the signal received by the nth positioning antenna; Step 5. Multiply the target wave expression and the reference wave expression by their conjugates to obtain the holographic pattern. : The superscript * indicates taking the conjugate; For the y-polarization direction, the phase difference between the two parts of the reference wave propagating in the vertical direction is 180° to correct for the holographic pattern, resulting in the following corrected holographic pattern: For the x-polarization direction, a 180° phase difference between the two parts of the reference wave propagating in the left and right directions is used for correction, resulting in the corrected holographic pattern: The real part of the holographic sample is extracted and normalized to obtain the normalized holographic sample value at any point in the liquid crystal holographic phased array. for: Where Re denotes taking the real part, and These represent the maximum and minimum values ​​of the holographic pattern at each point in the liquid crystal holographic phased array, respectively. If the normalized holographic pattern value If the value is greater than the set threshold 'a', the corresponding radiating element is in the "on" state; if the normalized holographic pattern value... If the value is less than the set threshold a, the corresponding radiating element is in the "off" state. The FPGA control circuit regulates the liquid crystal dielectric constant of each radiating element through the bias network, thereby controlling the switching state of each radiating element. The reference wave is used as the excitation source to excite the liquid crystal holographic phased array, which radiates energy signals into space to achieve adaptive focusing at the receiving end. Step 6. The receiving antenna receives the energy signal and sends it to the rectifier circuit module. The rectifier circuit module converts the received radio frequency signal into a DC signal for energy storage.

7. The millimeter-wave adaptive wireless power transmission method based on a liquid crystal holographic phased array antenna according to claim 6, characterized in that, In step 2, the power request signal received by each positioning antenna is at the same frequency as the local oscillator signal, and the power request signal received by the positioning antenna is denoted as... The local oscillator signal is denoted as The signal after mixing for: in, The angular frequency of the power request signal received by the positioning antenna. For time; For signal Perform low-pass filtering to obtain This completes the phase information of the signals received by each positioning antenna. Extraction.

8. The millimeter-wave adaptive wireless power transmission method based on a liquid crystal holographic phased array antenna according to claim 6, characterized in that, In step 3, ,in Let be the distance from the receiver to the nth positioning antenna; with each positioning antenna as the center of the sphere, the corresponding distance is... The location of the receiver is the common intersection of all the spheres, which serve as the radius.

9. The millimeter-wave adaptive wireless power transmission method based on a liquid crystal holographic phased array antenna according to claim 6, characterized in that, The dielectric constants of the liquid crystal corresponding to the "on" and "off" states of the radiating unit are 3.8 and 2.7, respectively, and the threshold value α is set to a range of 0.5 to 0.9.

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