2.45 GHz and 5.8 GHz double-frequency flexible antenna array for wireless microwave energy transmission

Abstract

The invention belongs to the field of wireless energy transmission, and discloses a 2.45 GHz and 5.8 GHz double-frequency flexible antenna array for wireless microwave energy transmission, which comprises a dielectric substrate, a patch array, a feed interface, an equivalent grounding plate, a metasurface layer and an EBG (Electromagnetic Band Gap) structure, the antenna structure is printed on one side of the dielectric substrate and is excited in a coaxial feed mode, an air layer is arranged between the two substrates, a certain distance is reserved between the two patches from side to side, and the two patches are subjected to 2 * 2 array expansion, so that a double-frequency flexible antenna array is formed. The dual-frequency antenna designed by the invention can work in different frequency bands, and can realize better performance and compatibility. And a flexible material and liquid metal are adopted, so that certain self-adaptability is achieved. By optimizing the design of the EBG structure, the isolation degree between the ports at the two working frequency points is remarkably improved, the mutual interference between the ports is effectively reduced, and the stable performance of the antenna array is ensured.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the field of wireless energy transmission technology, and in particular relates to a 2.45 GHz and 5.8 GHz dual-frequency flexible antenna array for wireless microwave energy transmission. Background Art

[0002] Microwave receiving antennas and rectifier circuits are important components of microwave energy transmission systems. Especially as the receiving end, new receiving antennas with high energy collection and conversion efficiency, convenient and fast laying methods, easy conformity with the structure of the load equipment, and certain self-repair capabilities are of great value to the promotion and application of microwave energy transmission.

[0003] Existing antennas designed for a single frequency often struggle to meet complex communication and energy transmission requirements. Different application scenarios may require operation in different frequency bands to achieve better performance and compatibility. Furthermore, in practical applications, a single antenna unit often fails to meet the system's requirements for higher gain and stronger directivity. Therefore, using multiple antenna units arranged in a specific pattern to form an antenna array has become an effective way to further improve antenna performance.

[0004] Therefore, this invention utilizes liquid metal printing technology and flexible materials to create a liquid metal dual-band flexible antenna array for microwave energy transmission operating at 2.45 GHz and 5.8 GHz. This liquid metal patch antenna leverages the repairability, flexibility, reconfigurability, fatigue resistance, and corrosion resistance of liquid gallium-indium metal and a flexible dielectric substrate. It can be used in integrated small electronic devices to receive and transmit electromagnetic waves, and for wireless energy transmission over long distances.

[0005] In view of the above analysis, the technical problems that need to be solved urgently in the existing technology are:

[0006] (1) Traditional single-frequency antennas are difficult to meet complex communication needs;

[0007] (2) Traditional antenna arrays have poor conformality, are difficult to resist mechanical deformation, and have poor environmental adaptability. Summary of the Invention

[0008] In response to the problems existing in the prior art, the present invention provides a 2.45 GHz and 5.8 GHz dual-frequency flexible antenna array for wireless microwave energy transmission.

[0009] The present invention is implemented as follows: a 2.45GHz and 5.8GHz dual-band flexible antenna array for wireless microwave energy transmission, characterized in that the 2.45GHz and 5.8GHz dual-band flexible antenna array for wireless microwave energy transmission mainly includes a dielectric substrate, a patch array, a feeding interface, an equivalent ground plate, a metasurface layer, and an EBG electromagnetic band gap structure; the antenna structure is printed on one side of the dielectric substrate and excited by coaxial feeding. There is an air layer between the two substrates, and a certain distance is left from edge to edge between the two patches. Both patches are expanded into a 2×2 array, thereby forming a dual-band flexible antenna array.

[0010] Furthermore, in the antenna array, the vertical and horizontal spacings of the rectangular patches on the left side are the same, while the vertical and horizontal spacings of the patches on the right side are different.

[0011] Furthermore, the antenna is composed of polyimide, an air layer, and a gallium-indium alloy. The antenna array is composed of multiple patch antenna units. The structure of the antenna unit consists of three layers, namely, a metal conductor, a dielectric substrate, an air layer, a dielectric substrate, and a metal reflector from top to bottom.

[0012] Furthermore, each layer of the dielectric substrate is made of polyimide (PI) material.

[0013] Furthermore, the equivalent ground plane is a very thin layer of copper, whose length and width are consistent with the dielectric substrate, and its thickness is much smaller than that of the dielectric substrate and approximately equal to the thickness of the patch array. In addition, at the same center of hole one (based on the coordinates of the center of the lower end of the cylindrical hollowing, the center coordinates are not at the same height, and there is a difference of one equivalent ground plane thickness in the Z direction), a cylinder with a radius larger than that of cylindrical hole one is dug out on the equivalent ground plane (named cylindrical hole two).

[0014] Furthermore, the feed interface mainly consists of an inner core, an outer core, and an outer ring:

[0015] The inner core is a short copper cylinder, the upper end of which is directly connected to the fourth transmission line on the patch antenna array through cylindrical hole 1 penetrating the dielectric substrate, and the lower end of which is extended beyond the equivalent ground plane through cylindrical hole 2;

[0016] The outer core is made of a circular cylinder made of insulating material Teflon, with a hole one having the same inner diameter as the cylinder and a hole two having the same outer diameter as the cylinder. The outer core is shorter than the inner core, wraps around the inner core, and is directly connected to the dielectric substrate.

[0017] The outer ring is made of copper and is also a cylindrical ring. The center of its bottom surface is the same as that of the inner core and the outer core. The inner diameter is the second cylindrical hole, and the outer diameter is three millimeters larger than the inner diameter.

[0018] Furthermore, the EBG electromagnetic bandgap structure is composed of a plurality of "S" shapes, which are formed by a microstrip line with a constant width being meandered at equal intervals.

[0019] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0020] First, the present invention is applied to the field of wireless energy transmission, has high gain and high efficiency, and can be applied to microwave wireless power transmission over longer distances.

[0021] The present invention can operate in two frequency bands, 2.45 GHz and 5.8 GHz, to meet complex communication and energy transmission requirements. It also adopts an electromagnetic gap (EBG) structure to significantly improve the isolation between ports at the two operating frequencies, effectively reducing mutual interference between ports, thereby ensuring the stable performance of the antenna array.

[0022] The antenna array dielectric substrate of the present invention is made of a flexible material, has good mechanical properties, can conform well to the load, and can be stretched, bent, twisted, and deformed while maintaining stable performance.

[0023] The patch antenna array of the present invention is made by liquid metal printing, can withstand a large degree of deformation, and has good conformality and certain adaptability.

[0024] Second, as auxiliary evidence for the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0025] The technical solution of the present invention solves the technical problems that people have been eager to solve but have never been able to solve successfully:

[0026] In the field of microwave energy transmission, as application scenarios continue to expand, the performance requirements for flexible receiving antennas are becoming increasingly stringent. For a long time, people hoped to solve problems such as narrow bandwidth, reduced gain under bending conditions, and performance degradation caused by multi-port antenna coupling in order to meet the needs of complex application scenarios, but success has always been unsuccessful.

[0027] The present invention effectively addresses these challenges through a series of technical solutions. To address the narrow bandwidth issue, a high-bandwidth flexible inkjet-printed antenna was designed. Secondary grooves were cut into the dielectric substrate to reduce the equivalent dielectric constant, increasing the absolute bandwidth by 0.31 GHz and improving efficiency and gain. Experiments have verified that it performs well in microwave energy transmission and reception. To address the issue of gain degradation under bending, a dual-band flexible antenna based on a zero-refractive-index metasurface was designed. By manipulating the wave vector using the metasurface, the gain of the bent antenna was significantly improved. For example, at a specific bending radius, the gain at 2.45 GHz and 5.8 GHz was significantly improved. Experiments also confirmed that the antenna received power increased after loading the metasurface. To address the coupling issue of multi-port antennas, a dual-band flexible antenna array was designed, using an EBG structure for decoupling and combining it with a zero-refractive-index metasurface for gain improvement. Simulations show that the EBG structure improves port isolation by 1.82 dB and 4.76 dB at the two operating frequencies, respectively. The metasurface also improves the gain of the antenna array under bending. For example, at a 50 mm bending radius, the gain at 2.45 GHz was significantly improved. Experiments also verified that the antenna array has good energy reception capabilities in complex environments.

[0028] (4) The technical solution of the present invention overcomes technical prejudice:

[0029] In the design of dual-band flexible antenna arrays, there has been a technical prejudice in the past that conventional decoupling methods such as parasitic elements and orthogonal polarization are applicable to all antenna decoupling scenarios. However, the present invention fully considers the characteristics of the designed antenna as a dual-band, dual-port antenna with a complex structure. Analysis shows that the design of parasitic elements depends on the antenna structure and frequency and has poor versatility. Orthogonal polarization is difficult to implement for established antennas. The DGS structure needs to design two structures for a dual-band, dual-port antenna, which is more troublesome. The use of metasurfaces for decoupling will make the structure more complex and increase losses. Finally, the EBG structure was selected to perform decoupling operations on the antenna array, successfully improving the isolation between ports, effectively reducing mutual interference between ports, ensuring the stable performance of the antenna array, overcoming this technical prejudice, and providing a more suitable method for decoupling dual-band flexible antenna arrays. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a top view of a dual-frequency antenna array provided by an embodiment of the present invention;

[0031] Figure 2 is a cross-sectional view of a dual-frequency antenna array provided by an embodiment of the present invention;

[0032] Figure 3 is a structural diagram of a unit patch antenna provided by an embodiment of the present invention;

[0033] Figure 4 is a top view of a dielectric substrate provided by an embodiment of the present invention;

[0034] Figure 5This is the actual structure of the feeding interface provided by the embodiment of the present invention;

[0035] Figure 6 This is a ground plate structure provided by an embodiment of the present invention;

[0036] Figure 7 This is a bird's-eye view of the supersurface layer provided by an embodiment of the present invention;

[0037] Figure 8 The EBG electromagnetic bandgap structure provided by an embodiment of the present invention is as follows: (a) electromagnetic bandgap structure; (b) antenna array after adding the electromagnetic bandgap structure;

[0038] Figure 9 is an energy band diagram of an EBG structure provided by an embodiment of the present invention;

[0039] Figure 10 This is the S-parameter simulation result of the antenna array with EBG structure provided by the embodiment of the present invention;

[0040] Figure 11 : These are the electric field distribution diagrams of the antenna array provided by an embodiment of the present invention at 2.45 GHz and 5.8 GHz: (a) without EBG structure; (b) with EBG structure;

[0041] Figure 12 is a schematic diagram of a microwave energy transmission experimental system according to an embodiment of the present invention;

[0042] Figure 13 4 is a comparison diagram of S parameters of antenna arrays according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] An embodiment of the present invention provides a 2.45 GHz and 5.8 GHz dual-frequency flexible antenna array for wireless microwave energy transmission. The patch antenna array mainly includes a dielectric substrate, a patch array, a feeding interface, an equivalent ground plate, a metasurface layer, and an EBG electromagnetic band gap structure.

[0045] The antenna structure is printed on one side of a dielectric substrate and excited via coaxial feeding. An air layer is placed between the two substrates, leaving a certain edge-to-edge spacing between the two patches. Both patches are expanded into a 2×2 array, forming a dual-band flexible antenna array. The rectangular patches on the left have the same spacing from top to bottom and from side to side, while the patches on the right have different spacing from top to bottom and from side to side.

[0046] Figure 1This is a top view of the antenna array structure. There are two antenna arrays in the figure, where array 1 is used to receive 2.45 GHz electromagnetic waves and array 2 receives 5.8 GHz electromagnetic waves.

[0047] Figure 2 is a cross-sectional view of the antenna array. Figure 3 This is a diagram of the structure of a single patch antenna. The antenna is composed of polyimide, an air layer, and a gallium-indium alloy. The antenna array is composed of multiple patch antenna units. The antenna unit structure consists of three layers: from top to bottom: a metal conductor, dielectric substrate 1, air layer, dielectric substrate 2, and a metal reflector.

[0048] Figure 4 3 is a top view of a dielectric substrate. Each layer of the dielectric substrate is made of polyimide (PI) material. Polyimide is a flexible material with good bending properties and the lowest loss tangent.

[0049] The present invention adopts a dual-frequency working mechanism. Array 1 and Array 2 are designed based on rectangular and multi-stage slot resonant cavity structures, corresponding to 2.45GHz and 5.8GHz operating frequencies respectively. This design fully utilizes the main mode (TM) of the patch antenna. 10 ) and higher order modes (such as TM 30 The resonance conditions between the two modes (or composite modes) are achieved by precisely controlling the electrical length through geometric parameters (such as W1, W2, ΔW, etc.) to meet the impedance matching conditions at two frequencies and realize dual-frequency excitation characteristics.

[0050] The antenna adopts coaxial probe feeding mode, forming a vertical local current channel at the probe feeding point. The excitation electric field is coupled to the edge electric field of the metal patch to form a stable surface current distribution. The optimization of the feeding point position (such as Figure 3 The parameter F) shown ensures that the input impedance can achieve a good standing wave ratio (SWR<2) at both frequency points.

[0051] The structure utilizes a three-layer stack of polyimide, air, and a metal reflective layer. The air layer acts as a low-dielectric dielectric, effectively reducing the structure's equivalent dielectric constant (ε_eff) and enhancing radiation efficiency. The polyimide layer's low loss tangent (tanδ≈0.002) ensures low-loss transmission characteristics at high frequencies, while also providing excellent flexible mechanical properties to adapt to a variety of wearable scenarios.

[0052] To ensure that coupling between antenna elements does not cause interference and bandwidth overlap, the array element spacing (Gap) is optimized through electromagnetic simulation to minimize the coupling capacitance between adjacent elements in the main lobe direction, improving the antenna array's directivity and isolation. Furthermore, the asymmetric layout in Array 2, where the vertical spacing is ≠ the horizontal spacing, helps improve frequency selectivity and polarization diversity in the 5.8 GHz band.

[0053] This structure incorporates an electromagnetic bandgap (EBG) structure with bandgap characteristics into the bottom layer of the dielectric substrate, which is loaded with periodic conductors to form an equivalent LC resonant unit. The EBG suppresses surface wave propagation within specific frequency bands (such as 2.2-2.7 GHz and 5.4-6.1 GHz), reducing lateral coupling between antennas, improving radiation efficiency and front-to-back ratio, and reducing interference from floor reflections on the main lobe.

[0054] By precisely adjusting the patch size, slot loading width (e.g., ΔW3 to ΔW7), and varying the array layout, the equivalent radiation aperture at low and high frequencies can be controlled. In Array 1, equidistant placement improves mainlobe gain and suppresses sidelobes. In Array 2, a spiral foldback structure creates multipath radiation, facilitating beam broadening and directivity adjustment at 5.8 GHz, meeting the requirements for high-throughput microwave energy harvesting.

[0055] The equivalent ground plane is essentially a very thin layer of copper, which plays the role of equivalent grounding. Its length and width are consistent with those of the dielectric substrate, and its thickness is much smaller than that of the dielectric substrate and is approximately equal to the thickness of the patch array. In addition, at the same center of hole 1 (based on the coordinates of the center of the lower end of the cylindrical hollowing, the center coordinates are not at the same height, and there is a difference of one equivalent ground plane thickness in the Z direction), a cylinder with a radius larger than that of cylindrical hole 1 is dug out on the equivalent ground plane (named cylindrical hole 2).

[0056] The feed interface mainly consists of an inner core, an outer core, and an outer ring.

[0057] The inner core is a small section of a copper cylinder, the upper end of which penetrates the dielectric substrate through a cylindrical hole 1 and is directly connected to the fourth transmission line on the patch antenna array, and the lower end of which extends beyond the equivalent ground plate through a cylindrical hole 2.

[0058] The outer core is a cylindrical section made of insulating Teflon, with a hole one of the same inner diameter and a hole two of the same outer diameter. It is shorter than the inner core, wraps around the inner core, and is directly connected to the dielectric substrate. (The inner and outer cores have the same bottom center. The outer core's height is the equivalent height plus the equivalent thickness, while the inner core's height is the equivalent height plus the equivalent thickness plus the dielectric substrate's thickness.)

[0059] The outer ring is made of copper and is also a cylindrical ring. The center of its bottom surface is the same as that of the inner core and the outer core, except that the inner diameter is the second cylindrical hole, and the outer diameter is three millimeters larger than the inner diameter.

[0060] Figure 5This is a schematic diagram of the feed interface. The cylindrical inner core penetrates the dielectric substrate and the equivalent ground plane, with its upper end directly connected to the patch antenna array, making it considered integral with the patch antenna array. The outer core is encased in an insulating outer core, the upper end of which is directly connected to the dielectric substrate. The outer core is surrounded by a very thin copper outer ring, which can be considered integral with the equivalent ground plane. This prevents the patch antenna array (equivalent to the positive electrode) from being connected to the equivalent ground plane (equivalent to the negative electrode) (separated by the inner core), while also providing a feed interface to power subsequent loads. Energy from the patch antenna array is transmitted to the feed interface via a transmission line. The feed interface then cascades with the next-level structure (mostly a rectifier circuit) to transmit the microwave energy to the next level.

[0061] Figure 6 This is a structural diagram of the equivalent ground plate and its connection with the feed interface. The inner core cooperates with the first cylindrical hole, and the outer core and outer ring cooperate with the second cylindrical hole, realizing the connection between the feed interface and the entire antenna structure.

[0062] Figure 7 This is the structure diagram of the super surface layer. The super surface layer is attached to the upper part of the dielectric substrate. Figure 8 This is the EBG electromagnetic band gap structure diagram, Figure 9 This is the structural diagram of the antenna after adding the EBG electromagnetic band gap structure. Adding the EBG structure between the two antenna arrays can perform decoupling operations to ensure the stable performance of the antenna array.

[0063] The EBG electromagnetic band gap structure is composed of a plurality of "S" shapes, which are formed by a microstrip line with a constant width being meandered at equal intervals.

[0064] Figure 9 is the EBG structure band diagram, Figure 10 S-parameter simulation results of antenna array with EBG structure, Figure 11 The electric field distribution of the antenna array at 2.45 GHz and 5.8 GHz is shown in Figure 2. It can be seen that the electric field in the area between the two antenna sections is significantly reduced after the EBG structure is added, which is consistent with decoupling theory. Furthermore, the EBG structure is also made of liquid metal, so its use does not affect the integration and flexibility of the antenna array.

[0065] Wireless Energy Transmission System: The high-bandwidth flexible antenna unit, dual-band flexible antenna based on a zero-refractive-index metasurface, and dual-band flexible antenna array designed in this invention can be applied to various wireless energy transmission systems. During microwave energy transmission, these antennas can efficiently receive microwave energy, improving energy transmission efficiency. For example, in drone energy replenishment scenarios, the microwave energy transmission system can continuously power the drone, extending its flight time and addressing battery capacity limitations.

[0066] Implantable Medical Devices: This invention's flexible antenna exhibits excellent flexibility, making it suitable for use in implantable medical devices. It can provide wireless charging for implantable devices, eliminating the hassle and surgical risks of traditional charging with wires, and improving patients' quality of life. Devices such as pacemakers, for example, can be wirelessly charged by receiving microwave energy through the flexible antenna, reducing the need for frequent battery replacement or recharging surgeries.

[0067] Sensor networks: In sensor networks, the antennas of this invention can remotely power distributed sensor devices. Their high bandwidth and excellent reception performance ensure stable energy reception for sensors, eliminating the inconvenience of frequent battery replacements and guaranteeing long-term stable operation of the sensor network. For example, in environmental monitoring sensor networks, sensors can use these antennas to receive microwave energy for continuous data collection and transmission.

[0068] Wearable devices: Due to their flexibility, the flexible antennas and antenna arrays designed based on this invention can be applied to wearable devices. In wearable products such as smart wristbands and smart clothing, they can achieve wireless communication and energy reception without compromising wearable comfort and convenience. For example, a smart wristband can receive microwave energy for charging through these antennas while simultaneously enabling stable communication with other devices.

[0069] Table 1 compares this chapter's work with other references, showcasing the performance of various studies in terms of frequency, isolation, and gain, highlighting the strengths of this paper. In terms of isolation, this paper achieves 30.07 dB and 52.96 dB in the 2.45 GHz and 5.8 GHz bands, respectively, outperforming other references and demonstrating its superior interference suppression capabilities. In terms of gain, this paper achieves 9.9 dBi and 13.68 dBi in the 2.45 GHz and 5.8 GHz bands, respectively, which is generally higher than most of the referenced work. Furthermore, this paper reports gain* (dBi), which is 2.64 dBi and 0.81 dBi in the 2.45 GHz and 5.8 GHz bands, further demonstrating its unique characteristics. Notably, this design exhibits flexibility, improving adaptability and scalability compared to some rigid solutions. Therefore, this research demonstrates outstanding performance in both isolation and gain, while also being flexible, providing excellent technical support for microwave wireless energy transmission applications.

[0070] Table 1 Comparison with other literature works

[0071]

[0072] Gain* indicates the maximum gain improvement of the antenna when it is bent.

[0073] References:

[0074] [1] Xiao Z J, Cao Y F, Lin J S, et al. Dual-Band Shared-Aperture Base-Station Antenna Array With Dual Polarization Using Filtering Magnetoelectric Dipole Antenna[J]. IEEE Open Journal of Antennas and Propagation, 2024, 5(1): 82 - 89.

[0075] [2] Ge L, Wang Y, Du M, et al. A Dual-Band Dual-Polarized Base Station Antenna Array With Isolation Enhancement[J]. IEEE Open Journal of Antennas and Propagation, 2023, 4: 871 - 877.

[0076] [3] Tiwari R N, Sharma D, Singh P, et al. Design of Dual-Band 4-Port Flexible MIMO Antenna for mm-Wave Technologies and Wearable Electronics[J]. IEEE Access, 2024, 12: 96649 - 96659.

[0077] [4] Liang C, Yang W, Xue Q, et al. Wideband High-Transparent Dipole Antenna Based on Frequency Selective Surface and Its Applications in Dual-Band Shared-Aperture Array[J]. IEEE Antennas and Wireless Propagation Letters, 2025, 24(3): 572 - 576.

[0078] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A dual-frequency flexible patch antenna array for wireless microwave energy transmission, characterized in that: Including dielectric substrate, metal patch array, coaxial feeding structure, equivalent metal ground layer, metasurface structure and electromagnetic bandgap structure (EBG), The metal patch array is arranged on the upper surface of the dielectric substrate, the coaxial feeding structure passes through the dielectric substrate and is electrically connected to the patch array, and the equivalent ground layer is arranged below the dielectric substrate and is electrically isolated from the feeding structure. The patch array consists of a rectangular patch unit array on the left and a multi-level ring patch unit array on the right, which are arranged in a 2×2 array. The left patch has equal spacing up and down and left and right, while the right patch has unequal spacing up and down and left and right. An air layer is provided between the patch array, the ground layer and the metasurface structure. The dielectric substrate is made of polyimide material, and the electromagnetic bandgap structure is arranged between the substrate and the ground layer, and is composed of a periodic array of "S"-shaped microstrip line units.

2. The dual-band flexible patch antenna array according to claim 1, wherein: The patch unit is composed of a multi-stage closed rectangular ring with decreasing size from the outside to the inside, and the spacing between the patches at each stage is a step-by-step decreasing value from ΔW1 to ΔW5.

3. The dual-band flexible patch antenna array according to claim 1, wherein: The feed structure includes a central conductor, a dielectric insulating core and an outer conductor ring, The central conductor is a copper cylinder, the upper end of which is directly welded to the lower surface of the patch array. The dielectric insulating core is made of polytetrafluoroethylene material. The outer conductor ring is a copper ring structure. The central conductor and the outer conductor ring are respectively located on the same cylindrical axis.

4. The dual-band flexible patch antenna array according to claim 1, wherein: The equivalent grounding layer is made of copper foil, the length and width of which are consistent with the dielectric substrate, and the thickness is less than 1 / 5 of the thickness of the patch array. A cylindrical hollow structure is provided at the center of the grounding layer, and the diameter of the cylindrical hollow structure is larger than the diameter of the circular hole through which the feeding structure penetrates the dielectric layer.

5. The dual-band flexible patch antenna array according to claim 1, wherein: The metasurface structure is a periodic conductor pattern printed between the patch array and the air layer. The conductor pattern is arranged in a checkerboard pattern and is used to construct a surface wave suppression area that matches the free space impedance.

6. The dual-band flexible patch antenna array according to claim 1, wherein: The "S"-shaped microstrip line unit in the electromagnetic bandgap structure is composed of a conductor of constant width, which is periodically arranged in a meandering pattern along the XY plane, and the period length is a multiple of λ / 4 of the central working wavelength of the electromagnetic wave.

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