A two-dimensional scanned leaky-wave antenna array for wireless energy transfer

Abstract

The application belongs to the technical field of wireless energy transmission, and specifically provides a two-dimensional scanning leaky-wave antenna array for wireless energy transmission, aiming at a far-field wireless energy transmission application scenario, using the unique beam frequency scanning characteristics of the leaky-wave antenna to realize passive beam forming, avoiding the use of active phased arrays and digital metasurface transmitters with extremely high cost and high power loss, further combining one-dimensional large-angle scanning leaky-wave antennas with one-eighth stripline power division feed networks with large phase shift characteristics to realize high-gain two-dimensional continuous scanning beams, the two-dimensional continuous scanning leaky-wave antenna can map the continuous frequency signals transmitted at a single port to different but continuous spatial angles, aiming to serve as a low-cost and high-efficiency wireless energy transmission transmission platform to provide power for multiple moving targets for remote tracking without dead angles, and showing great potential in actual application.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, specifically providing a two-dimensional scanning leaky wave antenna array for wireless power transmission. Background Technology

[0002] In recent years, the emergence of the Qi standard has greatly promoted the development of wireless charging technology for smartphones and sensor devices; however, although this standard brings the convenience of being free from cables, it still has significant shortcomings in achieving truly long-distance (over 200cm) and mobile device charging. Therefore, finding solutions that can support long-distance and mobile charging has become a current research hotspot.

[0003] Far-field wireless power transfer technology utilizing electromagnetic waves offers a potential solution for remote charging. However, this technology also faces significant challenges in application: radiated wireless power is easily scattered in open environments, and electromagnetic waves experience significant path loss when propagating in free space, resulting in relatively low end-to-end efficiency of far-field wireless power transfer systems. For example, a method for evaluating and optimizing the wireless power transfer efficiency and gain of electromagnetic metasurfaces, proposed in Chinese patent document CN117811631A, is based on the Friesian transport equation and the principle of electric field superposition. It treats metasurface units as independent radiators and calculates the superposition of electromagnetic waves influenced by each unit at the receiver or the far field of the metasurface. This method can effectively improve the performance of metasurface-based wireless power transfer, wireless communication, and energy-carrying communication systems. However, this method is based on electromagnetic metasurfaces, requiring a large number of active diodes, resulting in high cost and complex design. For example, Chinese patent document CN118094888A proposes a modular design method for microwave wireless power transmission active phased array transmitting antennas. This method reduces the engineering implementation difficulty and manufacturing cost of transmitting antennas while meeting high transmission efficiency. It can effectively design active phased array transmitting antennas with high beam collection efficiency, high security and low cost. However, this design method is based on active phased arrays, which requires a large number of active phase shifters and power amplifiers, resulting in high cost and complex design.

[0004] In summary, to address the numerous problems existing in current far-field wireless power transmission technologies, this invention proposes a two-dimensional scanning leaky wave antenna array for wireless power transmission, which serves as the transmitting antenna of a wireless power transmission system to remotely track and power multiple moving targets. Summary of the Invention

[0005] The purpose of this invention is to provide a two-dimensional scanning leaky wave antenna array for wireless power transmission. Targeting far-field wireless power transmission applications, it utilizes the unique frequency-scanning characteristic of leaky wave antennas to achieve passive beamforming, avoiding the use of high-cost and high-power-loss active phased arrays and digital metasurface transmitters. Furthermore, it combines a one-dimensional large-angle scanning leaky wave antenna with an eight-way stripline power divider network with large phase shift characteristics to achieve a high-gain two-dimensional continuous scanning beam. This two-dimensional continuous scanning leaky wave antenna can map continuous frequency signals transmitted at a single port to different but continuous spatial angles. It aims to serve as a low-cost, high-efficiency wireless power transmission platform, providing power for long-range tracking of multiple moving targets without blind spots, demonstrating great potential in practical applications.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A two-dimensional scanning leaky antenna array for wireless power transmission is characterized in that the two-dimensional scanning leaky antenna array adopts a three-layer PCB substrate structure, including: an SMA coaxial connector to stripline vertical transition structure, a 1 to 8 stripline power divider feed network, a stripline to microstrip vertical transition structure, an attenuator, a power amplifier, and a leaky antenna array.

[0008] The lower surface of the lower PCB substrate is provided with a lower metal ground plane, the upper surface of the lower PCB substrate is provided with a 1 to 8 stripline power divider feed network, the upper surface of the middle PCB substrate is provided with an upper metal ground plane, and the upper surface of the upper PCB substrate is provided with an attenuator, a power amplifier and a leaky antenna array.

[0009] The SMA coaxial connector to stripline vertical transition structure is set on the lower surface of the lower PCB substrate to transmit RF signals to the 1 to 8 stripline power divider feed network.

[0010] The 1-to-8 stripline power divider network consists of 7 cascaded unequal T-junction power dividers, with phase delay lines connecting adjacent unequal T-junction power dividers, so that the phase of the eight outputs of the 1-to-8 stripline power divider network meets the preset frequency sweep characteristics.

[0011] The leaky antenna array consists of eight leaky linear arrays arranged in parallel. Each of the eight leaky linear arrays corresponds one-to-one with the eight outputs of the 1-to-8 stripline power divider network. Each output of the 1-to-8 stripline power divider network is connected to an attenuator through a stripline-to-microstrip vertical transition structure, so that the amplitudes of the eight outputs of the 1-to-8 stripline power divider network are kept consistent after being adjusted by the attenuator. The output of the attenuator is then transmitted to the leaky linear array after being amplified by a power amplifier.

[0012] Furthermore, the SMA coaxial connector to stripline vertical transition structure includes: an SMA coaxial connector, a circular isolation groove, a pad, and a first short-circuit metal post. The outer conductor of the SMA coaxial connector is connected to the lower metal ground plane. The lower metal ground plane has a circular isolation groove corresponding to the inner conductor of the SMA coaxial connector. The center of the circular isolation groove is provided with a pad connecting the inner conductor of the SMA coaxial connector. The pad is connected to the input end of the 1-to-8 stripline power distribution network through a metal through-hole penetrating the lower PCB substrate. Several first short-circuit metal posts are arranged around the circular isolation groove. The first short-circuit metal posts penetrate the lower PCB substrate and the middle PCB substrate and then connect the lower metal ground plane and the upper metal ground plane.

[0013] Furthermore, the phase conditions of the eight outputs of the 1-to-8 stripline power divider network are as follows:

[0014] ,in, This indicates the transmission phase from output port i to input port i. Indicates operating frequency A fixed phase difference, and at each operating frequency within the operating frequency band. It meets the frequency sweep characteristics.

[0015] Furthermore, the phase delay line adopts a serpentine bend strip structure.

[0016] Furthermore, the stripline-to-microstrip vertical transition structure includes: a central metal pillar, a low-impedance microstrip line, and a second short-circuit metal pillar. The low-impedance microstrip line is connected to the input port of the attenuator. The central metal pillar passes through the upper PCB substrate and the middle PCB substrate and then connects the low-impedance microstrip line to the output port of the 1-to-8 stripline power divider network. A circular isolation groove is formed on the upper metal ground plane corresponding to the central metal pillar. Several second short-circuit metal pillars are arranged around the circular isolation groove 8 and pass through the middle PCB substrate and the lower PCB substrate, then connect the upper metal ground plane and the lower metal ground plane.

[0017] Furthermore, the leaky wave array is composed of several leaky wave units connected sequentially. Each leaky wave unit consists of a microstrip conductor, two rectangular radiating stubs, and four slow-wave stubs, and the leaky wave unit is 180° rotationally symmetrical around its center. Adjacent leaky wave units are connected sequentially through the microstrip conductor. The first to fourth slow-wave stubs are all vertically connected to the microstrip conductor. The first rectangular radiating stub is located between the first and second slow-wave stubs, and the second rectangular radiating stub is located between the third and fourth slow-wave stubs. The two rectangular radiating stubs are staggered on both sides of the microstrip conductor. The length L1 of the rectangular radiating stub is greater than L2 / 2, where L2 is the length of the slow-wave stub.

[0018] Furthermore, the attenuator is composed of a phase shifter connected to a Π-type attenuator. The Π-type attenuator is used to adjust the signal amplitude so that the amplitudes of the eight outputs of the 1-to-8 stripline power divider are consistent after passing through the attenuator. The phase shifter is used to compensate for the phase shift generated by the Π-type attenuator so that the phases of the eight outputs of the 1-to-8 stripline power divider remain unchanged after passing through the attenuator.

[0019] Furthermore, the power amplifier amplifies the signal power to the watt level.

[0020] Based on the above technical solution, the beneficial effect of the present invention is that it provides a two-dimensional scanning leaky wave antenna array for wireless power transmission, which has the following advantages:

[0021] 1. This invention combines an ultra-high phase delay feed network with a large-angle scanning leaky wave antenna. It utilizes the periodic phase scanning formed by the ultra-high phase delay feed network and the high-gain frequency-scanning beam formed by the leaky wave antenna to achieve two-dimensional large-space continuous beam coverage, which can be used for long-distance wireless tracking and power transmission of multiple targets. Furthermore, this two-dimensional continuous scanning leaky wave antenna architecture does not require complex active devices for beam control, and has significant advantages in terms of simple structure and low cost.

[0022] 2. This invention proposes an 8-to-1 stripline power divider feeder network with large phase shift characteristics. This feeder network utilizes the low loss advantage of striplines, achieving ultra-high phase delay while exhibiting low loss characteristics within the operating frequency band, thereby effectively improving the gain of the two-dimensional continuous scanning leaky wave antenna and enabling power transmission to targets at greater distances. Simultaneously, due to the varying degrees of loss introduced by the 8-to-1 stripline power divider feeder network, to ensure consistent amplitude of the eight output signals, this invention introduces attenuators with different attenuation values ​​to maintain consistent amplitude across the eight outputs. Furthermore, a phase shifter is added to the attenuator module to adjust the phase, ensuring that the phase of the eight outputs of the 8-to-1 stripline power divider feeder network remains unaffected.

[0023] 3. This invention introduces a power amplifier after the attenuator, so that the power of each output signal reaches the watt level, thereby enabling charging of targets at a greater distance, or charging of targets at the same distance with greater power. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the two-dimensional scanning leaky antenna array used for wireless power transmission in this invention;

[0025] Figure 2 This is a schematic diagram of the SMA coaxial connector to strip wire vertical transition structure in this invention;

[0026] Figure 3This is a schematic diagram of the unequal-division T-junction power divider in this invention;

[0027] Figure 4 This is a schematic diagram of the phase delay line in this invention;

[0028] Figure 5 A schematic diagram of the vertical transition structure from stripline to microstripline in this invention;

[0029] Figure 6 This is a schematic diagram of the structure of the two-dimensional continuous scanning leaky wave antenna leaky wave unit in this invention;

[0030] Figure 7 This is a schematic diagram of the attenuator structure in this invention;

[0031] In the above figures, 1 is the SMA coaxial connector to stripline vertical transition structure, 2 is the 1 to 8 stripline power divider feed network, 3 is the stripline to microstrip vertical transition structure, 4 is the attenuator, 5 is the power amplifier, 6 is the leaky antenna array, 7 is the SMA coaxial connector, 8 is the circular isolation slot, 9 is the pad, 10 is the unequal T-junction power divider, 11 is the phase delay line, 12 is the second short-circuit metal pillar, 13 is the center metal pillar, 14 is the low-impedance microstrip line, 15 is the rectangular radiating stub, 16 is the slow wave stub, 17 is the phase shifter, and 18 is the Π-type attenuator. Detailed Implementation

[0032] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] This embodiment provides a two-dimensional scanning leaky antenna array for wireless power transmission, which is designed using a three-layer PCB substrate and includes: an SMA coaxial connector to stripline vertical transition structure 1, a 1 to 8 stripline power divider feed network 2, a stripline to microstrip vertical transition structure 3, an attenuator 4, a power amplifier 5, and a leaky antenna array 6.

[0034] The 1-to-8 stripline power divider network 2 is disposed on the upper surface of the lower PCB substrate (and is also located on the lower surface of the middle PCB substrate). The lower surface of the lower PCB substrate is provided with a lower metal ground plane, and the upper surface of the middle PCB substrate is provided with an upper metal ground plane (and is also located on the lower surface of the upper PCB substrate). The attenuator 4, the power amplifier 5 and the leaky antenna array 6 are disposed on the upper surface of the upper PCB substrate.

[0035] The SMA coaxial connector to stripline vertical transition structure 1 is disposed on the lower surface of the lower PCB substrate, transmitting the radio frequency signal to the 1-to-8 stripline power divider feed network 2; the SMA coaxial connector to stripline vertical transition structure is as follows: Figure 2As shown, the structure includes: an SMA coaxial connector 7, a circular isolation groove 8, a pad 9, and first short-circuit metal pillars. The outer conductor of the SMA coaxial connector 7 is connected to the lower metal ground plane. The lower metal ground plane has a circular isolation groove 8 corresponding to the inner conductor of the SMA coaxial connector 7, and a pad 9 is set at the center of the circular isolation groove 8. The pad 9 is connected to the input end of the 1-to-8 stripline power divider network 2 through a metal through-hole penetrating the lower PCB substrate. Several first short-circuit metal pillars are arranged around the circular isolation groove 8 and penetrate the lower PCB substrate and the middle PCB substrate before connecting the lower metal ground plane and the upper metal ground plane. In the SMA coaxial connector to stripline vertical transition structure 1, on the one hand, the width of the inner conductor of the SMA coaxial connector 7 is adjusted by the pad 9 to achieve good impedance matching and ensure signal transmission; on the other hand, the short-circuit metal pillars arranged around the circular isolation groove 8 effectively prevent the generation of other resonant modes.

[0036] The 1-to-8 stripline power divider network includes: an unequal-division T-junction power divider 10 and a phase delay line 11. The 1-to-8 stripline power divider network is composed of 7 cascaded unequal-division T-junction power dividers, and adjacent unequal-division T-junction power dividers are connected by phase delay lines 11, so that the output phase of the 8 output ports of the 1-to-8 stripline power divider network satisfies: ,in, This indicates the transmission phase from input port i to output port i. Indicates operating frequency A specific phase difference, and at various operating frequencies within the operating frequency band. It satisfies frequency sweep characteristics; furthermore, the unequal-division T-junction power divider is as follows: Figure 3 As shown, the phase delay line adopts a serpentine, bent strip-shaped structure, such as... Figure 4 As shown;

[0037] The leaky antenna array 6 includes eight leaky linear arrays, each corresponding to one of the output ports of the 1-to-8 stripline power divider network. Each output port of the 1-to-8 stripline power divider network is connected to attenuator 4 through a stripline-to-microstrip vertical transition structure to ensure that the output amplitudes of the eight output ports of the 1-to-8 stripline power divider network are consistent. The output of attenuator 4 is transmitted to the leaky linear array after passing through power amplifier 5, which enables the signal power to reach the watt level.

[0038] Furthermore, the vertical transition structure from stripline to microstrip line is as follows: Figure 5As shown, the structure includes: a central metal pillar 13, a low-impedance microstrip line 14, and a second short-circuit metal pillar 12. The low-impedance microstrip line 14 is connected to the input port of the attenuator 4. The central metal pillar 13 passes through the upper PCB substrate and the middle PCB substrate and then connects the low-impedance microstrip line 14 to the output port of the 1-to-8 stripline power divider network. A circular isolation groove is formed on the upper metal ground plane corresponding to the central metal pillar 13. Several second short-circuit metal pillars are arranged around the circular isolation groove 8 and pass through the middle PCB substrate and the lower PCB substrate, then connect the upper metal ground plane and the lower metal ground plane. In the stripline to microstrip line vertical transition structure, the second short-circuit metal pillars effectively suppress the generation of other modes. At the same time, the low-impedance microstrip line with a wider width at one end achieves good impedance matching, ensuring signal transmission.

[0039] Furthermore, the leaky wave array is composed of a plurality of leaky wave elements connected sequentially. In this embodiment, the leaky wave array is composed of 25 leaky wave elements, as shown in the example below. Figure 6 As shown, the system consists of a microstrip conductor, two rectangular radiating stubs, and four slow-wave stubs, with the drain element rotating symmetrically at 180° around its center. Adjacent drain elements are connected sequentially via the microstrip conductor. The first to fourth slow-wave stubs are all perpendicularly connected to the microstrip conductor. The first rectangular radiating stub is positioned between the first and second slow-wave stubs, and the second rectangular radiating stub is positioned between the third and fourth slow-wave stubs. The two rectangular radiating stubs are staggered on both sides of the microstrip conductor. The length L1 of the rectangular radiating stub is greater than L2 / 2, where L2 is the length of the slow-wave stub.

[0040] Furthermore, the attenuator 4 is as follows: Figure 7 As shown, it is composed of a phase shifter 17 and a Π-type attenuator 18. The Π-type attenuator 18 adjusts the signal amplitude so that the output amplitudes of the eight output ports of the 1-to-8 stripline power divider are consistent. The phase shifter 17 is used to compensate for the phase shift generated by the Π-type attenuator 18 so that the output phases of the eight output ports of the 1-to-8 stripline power divider are not affected.

[0041] In summary, the present invention provides a two-dimensional scanning leaky antenna array for wireless power transfer, which has the following advantages:

[0042] 1. To address the issues of short transmission distance and high system cost in wireless power transmission applications, this invention proposes a low-cost two-dimensional continuous scanning leaky wave antenna array. It combines a feed network with large phase shift characteristics with a large-angle scanning leaky wave antenna, achieving high-gain beam coverage in continuous space with simple structure and low cost.

[0043] 2. To address the problems of existing technologies that cannot track and charge moving targets and that only one target can be charged, the present invention proposes a two-dimensional continuous scanning leaky wave antenna that transmits a frequency sweep signal of the working frequency band at a known rate within a specified time. The DC power received by the rectifier antenna on the charging target is monitored in real time and synchronized with the transmission time of the frequency sweep signal of the two-dimensional continuous scanning leaky wave antenna. When a peak DC output is detected, the charging target sends a beacon signal to the transmitting platform, indicating the optimal time corresponding to the beam angle at a specific transmission signal frequency. In this way, the beam angle and optimal frequency of the charging target relative to the transmitting platform can be calculated based on the optimal time, thereby realizing the tracking and charging of moving targets. Moreover, this method can charge multiple targets simultaneously.

[0044] 3. To address the issue of limited energy transfer coverage, this invention utilizes a periodic phase scan formed by a feed network with large phase shift characteristics and a high-gain frequency-scanning beam formed by a large-angle scanning leaky antenna to achieve continuous two-dimensional large spatial beam coverage, enabling energy transfer and charging of moving targets in different spatial ranges.

[0045] 4. To address the limitation of high loss in the feed network of two-dimensional leaky wave antennas, this invention proposes a 1-to-8 stripline power divider feed network with large phase shift characteristics. This feed network utilizes the low loss advantage of striplines, achieving ultra-high phase delay while exhibiting low loss characteristics in the operating frequency band, thereby effectively improving the gain of the two-dimensional continuous scanning leaky wave antenna and enabling power transmission to targets at greater distances.

[0046] 5. To address the varying degrees of loss issues caused by the 1-to-8 stripline power divider network, this invention adds attenuators with different attenuation values ​​after the output port of the power divider network to ensure that the amplitudes of the eight signals output from the 1-to-8 stripline power divider network are consistent. At the same time, to ensure that the phase of each output is consistent, a phase shifter is added to the attenuator module to adjust the phase, so that the output phase of the eight output ports of the 1-to-8 stripline power divider network is not affected.

[0047] 6. To address the losses and attenuation introduced by the power supply network and attenuators, this invention adds a power amplifier after the attenuator, enabling the power of each output signal to reach the watt level, thereby enabling charging of targets at greater distances, or charging of targets at the same distance with greater power.

[0048] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A two-dimensional scanning leaky-wave antenna array for wireless power transfer, characterized in that, The two-dimensional scanning leaky antenna array adopts a three-layer PCB substrate structure, including: an SMA coaxial connector to stripline vertical transition structure, a 1 to 8 stripline power divider feed network, a stripline to microstrip vertical transition structure, an attenuator, a power amplifier and a leaky antenna array. The lower surface of the lower PCB substrate is provided with a lower metal ground plane, the upper surface of the lower PCB substrate is provided with a 1 to 8 stripline power divider feed network, the upper surface of the middle PCB substrate is provided with an upper metal ground plane, and the upper surface of the upper PCB substrate is provided with an attenuator, a power amplifier and a leaky antenna array. The SMA coaxial connector to stripline vertical transition structure is set on the lower surface of the lower PCB substrate to transmit RF signals to the 1 to 8 stripline power divider feed network. The 1-to-8 stripline power divider network consists of 7 cascaded unequal T-junction power dividers, with phase delay lines connecting adjacent unequal T-junction power dividers, so that the phase of the eight outputs of the 1-to-8 stripline power divider network meets the preset frequency sweep characteristics. The leaky antenna array consists of eight leaky linear arrays arranged in parallel. Each of the eight leaky linear arrays corresponds one-to-one with the eight outputs of the 1-to-8 stripline power divider network. Each output of the 1-to-8 stripline power divider network is connected to an attenuator through a stripline-to-microstrip vertical transition structure, so that the amplitudes of the eight outputs of the 1-to-8 stripline power divider network are kept consistent after being adjusted by the attenuator. The output of the attenuator is then transmitted to the leaky linear array after being amplified by a power amplifier.

2. The two-dimensional scanning leaky-wave antenna array for wireless power transmission according to claim 1, characterized in that, The SMA coaxial connector to stripline vertical transition structure includes: an SMA coaxial connector, a circular isolation groove, pads, and first short-circuit metal pillars. The outer conductor of the SMA coaxial connector is connected to the lower metal ground plane. The lower metal ground plane has a circular isolation groove corresponding to the inner conductor of the SMA coaxial connector. The center of the circular isolation groove is provided with a pad for connecting the inner conductor of the SMA coaxial connector. The pad is connected to the input end of the 1-to-8 stripline power divider network through a metal through-hole penetrating the lower PCB substrate. Several first short-circuit metal pillars are arranged around the circular isolation groove. The first short-circuit metal pillars penetrate the lower PCB substrate and the middle PCB substrate and then connect the lower metal ground plane and the upper metal ground plane.

3. The two-dimensional scanning leaky-wave antenna array for wireless power transmission according to claim 1, characterized in that, The phase conditions of the eight outputs of the 1-to-8 stripline power divider network are as follows: ,in, This indicates the transmission phase from output port i to input port i. Indicates operating frequency A fixed phase difference, and at each operating frequency within the operating frequency band. It meets the frequency sweep characteristics.

4. The two-dimensional scanning leaky antenna array for wireless power transfer according to claim 1, characterized in that, The phase delay line adopts a serpentine, bent strip structure.

5. The two-dimensional scanning leaky antenna array for wireless power transfer according to claim 1, characterized in that, The stripline-to-microstrip vertical transition structure includes: a central metal pillar, a low-impedance microstrip line, and a second short-circuit metal pillar. The low-impedance microstrip line is connected to the input port of the attenuator. The central metal pillar passes through the upper PCB substrate and the middle PCB substrate and then connects the low-impedance microstrip line to the output port of the 1-to-8 stripline power divider network. A circular isolation groove is formed on the upper metal ground plane corresponding to the central metal pillar. Several second short-circuit metal pillars are arranged around the circular isolation groove and pass through the middle PCB substrate and the lower PCB substrate, then connect the upper metal ground plane and the lower metal ground plane.

6. The two-dimensional scanning leaky antenna array for wireless power transfer according to claim 1, characterized in that, The leaky wave array is composed of several leaky wave units connected in sequence. Each leaky wave unit consists of a microstrip conductor, two rectangular radiating stubs, and four slow wave stubs, and the leaky wave unit is 180° rotationally symmetrical around the center. Adjacent leaky wave units are connected in sequence through the microstrip conductor. The first to fourth slow wave stubs are all vertically connected to the microstrip conductor. The first rectangular radiating stub is located between the first and second slow wave stubs, and the second rectangular radiating stub is located between the third and fourth slow wave stubs. The two rectangular radiating stubs are staggered on both sides of the microstrip conductor.

7. The two-dimensional scanning leaky-wave antenna array for wireless power transfer according to claim 6, characterized in that, The length L1 of the rectangular radial stub is greater than L2 / 2, where L2 is the length of the slow-wave stub.

8. The two-dimensional scanning leaky antenna array for wireless power transfer according to claim 1, characterized in that, The attenuator is composed of a phase shifter and a Π-type attenuator. The Π-type attenuator is used to adjust the signal amplitude so that the amplitudes of the eight outputs of the 1-to-8 stripline power divider are consistent after passing through the attenuator. The phase shifter is used to compensate for the phase shift caused by the Π-type attenuator so that the phases of the eight outputs of the 1-to-8 stripline power divider remain unchanged after passing through the attenuator.

9. The two-dimensional scanning leaky-wave antenna array for wireless power transfer according to claim 1, characterized in that, The power amplifier amplifies the signal power to the watt level.

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