Flexible antenna array and radio direction finding system
Through the combination of flexible double dipole patch antenna units and flexible dielectric substrates, an extended and bendable antenna array is designed, which solves the shortcomings of existing hard antenna arrays in terms of band width and flexibility, and achieves band widening, electromagnetic performance improvement and volume reduction, enhancing equipment adaptability and reducing costs.
Patent Information
- Application Number
- CN202510301546.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-06-06
AI Technical Summary
Existing hard antenna arrays have shortcomings in band width and flexibility, which makes it difficult to meet the needs of multi-band compatible and different sized devices in practical applications, and their large structures reduce usage flexibility and increase exposure risk.
Using a flexible double dipole patch antenna unit, combined with a flexible extendable dielectric substrate, an extendable and bendable antenna array is designed, and the working frequency band is widened through the resonant cavity, and a rectangular coupled patch is provided at the end of the radiation patch to improve current distribution.
The frequency band widening, electromagnetic performance improvement and volume reduction of antenna arrays are achieved, which enhances the adaptability to equipment of different sizes and shapes, reduces design and use costs, and increases the flexibility of application.
Smart Images
Figure CN120109497A_ABST
Abstract
Description
Technical Field The invention belongs to the technical field of flexible electronics, and in particular relates to a flexible antenna array and a radio direction finding system. Background Art Radio direction finding mainly utilizes the propagation properties of radio electromagnetic waves, and uses radio direction finding equipment to detect the arrival direction of unknown radio electromagnetic waves. It is of great value in radio spectrum management, eliminating the influence of unknown signals, and accurately locating the enemy's position. Interferometer direction finding is currently a widely used and relatively advanced direction finding method. It obtains the phase distribution of electromagnetic waves through antenna array elements and determines the incident direction of radio signals based on the phase distribution. When the radio wave is a plane wave, the relative position of the antenna array elements determines the phase distribution of the radio wave. By solving the phase difference of the received signal of each antenna array element in the antenna array, the relative position of the incoming wave can be obtained. Among them, the antenna array, as the receiving terminal of the electromagnetic wave, has the most direct impact on the direction finding accuracy and working ability of the interferometer direction finding technology. The antenna used in the interferometer direction finding technology is usually required to have wide-band and multi-band compatibility, dual-polarization configurability and good directional pattern uniformity. At present, most of the antennas used in interferometers are concentrated in the field of hard antennas, such as dipole antennas and Yagi antennas. Although these antennas can meet the performance requirements of interferometer direction finding, their unfolded sizes are extremely large. For example, the DF-A0085 direction finder of ALARIS and the AX-350D direction finder of WINRADIO have unfolded diameters of 3524 mm and 1520 mm respectively, which greatly reduces the flexibility in actual use and increases the risk of exposure during work. At the same time, the operating frequency bands of these antenna arrays are relatively narrow, and multiple sets of antenna arrays need to be replaced to achieve wide-band target direction finding and positioning. In order to broaden the working frequency band of the antenna array, there is a literature [1] The use of wideband antennas such as Vivaldi antennas can extend the operating frequency band of a single antenna to 0.3-3 GHz, but its operating size is still large, reaching 1000 mm. Some scholars have proposed the use of conformal patch antennas and their arrays. [2-4] It is adhered to the surface of the direction finder equipment to reduce its unfolded size, but the conformal shape of the object based on the hard substrate is fixed after the design is completed. Therefore, these hard conformal antennas can only be used for specific types of direction finders. When the model of the direction finder is changed, the antenna needs to be redesigned, which increases the operating cost of the overall system.
[0001] Mueller, Rainer et al. "A UHF ultrabroadband vivaldi-type directionfinding antenn a." 2010IEEE Antennas and Propagation Society InternationalSymposium(2010):1-4.
[0002] R.Mueller, C.Fuchs, R.Lorch and W.Menzel, "A conformal UHF slot type direction finding antenna with optimized Radar Cross Section," 2009IEEE Antennas and Propagation Society International Symposium, North Charleston, SC, USA, 2009, pp.1-4.
[0003] Tan, Moh Chuan et al. "A Flexible Low-Cost Hybrid Beamforming Structure for Practical Beamforming Applications." 2019IEEE International Symposium onRadio-Frequency Integration Technology(RFIT)(2019):1-3.
[0004] Liu, Chunxi et al. "Reconfigurable Antenna Array Direction FindingSystem Based on a Fast Search Algorithm." Sensors (Basel, Switzerland) 21 (2021): n.pag. Summary of the invention In view of the problems existing in the background technology, the purpose of the present invention is to provide a flexible antenna array and a radio direction finding system. In the present invention, each antenna unit is a symmetrical structure of a double dipole patch, and the double dipole patch is extended and designed, combined with the selection of a flexible and extensible dielectric substrate, so that the antenna array has good extensibility and bendability, thereby adapting to direction finder equipment of different sizes and shapes. To achieve the above object, the technical solution of the present invention is as follows: A flexible antenna array includes m×n antenna elements arranged in an array. The antenna element includes a flexible dielectric layer, a first radiation patch disposed on the upper surface of the dielectric layer, and a second radiation patch disposed on the lower surface of the dielectric layer; The second radiation patch is obtained by rotating the first radiation patch by 180°. The first radiation patch includes two identical radiation monopole patches, and each radiation monopole patch is composed of a central rectangular feeding area and a radiation area. The radiation area is an irregular heptagon, one side of which is connected to the central rectangular feeding area. A hexagonal resonant cavity is provided inside the heptagon away from the center of the dielectric layer to achieve resonant matching of electromagnetic waves of different wavelengths, so as to achieve the purpose of broadening the working frequency band of the original dipole patch unit. The hexagonal resonant cavity is composed of a trapezoid and a rectangle, and the lower bottom side of the trapezoid coincides with the long side of the rectangle. The rest of the radiation area except the resonant cavity is an extendable periodic grid structure. A rectangular coupling patch is also provided at the upper bottom side of the trapezoid near the edge of the dielectric layer to improve the current distribution in the corresponding area of the radiation monopole patch and improve the electromagnetic performance of the antenna; One radiation monopole patch in the first radiation patch and the opposite radiation monopole patch in the second radiation patch form a double dipole through a feeding interface. Among them, the feeding interface includes a central rectangular feeding patch and a through hole; The flexible antenna array is connected to the feeding interface through a coaxial cable for feeding. Further, the extendable periodic grid structure can be a fractal curve, a broken line, a serpentine line and other structures. Further, the serpentine line periodic grid structure is preferably a serpentine line. Among them, the serpentine line is obtained by periodically arranging unit structures. Each unit structure is obtained by rotating a semicircle by 90°, 180° and 270° in turn with one end point as the center point, and the whole is in the shape of a "卍". Further, the width of the serpentine line is 0.1-0.5 mm, and the radius of the arc segment of the serpentine line is 1-4 mm. Further, the materials of the first dipole patch and the second dipole patch are copper foils, and their thickness is 18μm-35μm. Further, the material of the flexible dielectric layer is polydimethylsiloxane (PDMS), Ecoflex, flexible liquid crystal material, etc. Further, the middle dielectric layer is selected as a PDMS material, and its thickness is a sub-wavelength thickness, which is 0.75-2 mm. The present invention also provides a radio direction finding system, including the above flexible antenna array, a GPS antenna, a monitoring direction finding receiver, an electronic compass, a control terminal and a power supply; The flexible antenna array is arranged below the GPS antenna and the electronic compass along a 360° circle. The number of antenna units of the flexible antenna array is equal to the number of receiving channels of the monitoring direction-finding receiver, and each antenna unit is connected to a receiving channel. The flexible antenna array is used to receive radio signals and feed the radio signals into the monitoring direction-finding receiver; the GPS antenna is used to provide geographic coordinate signals, and the electronic compass is used to provide direction information; The monitoring direction-finding receiver performs phase analysis and solution on the radio signal in combination with the geographic coordinate signal and the direction information, thereby obtaining the direction information of the incoming wave, and transmits the direction information of the incoming wave to the control terminal; the control terminal is used to display the positioning result. In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: Compared with traditional radio positioning antenna arrays, the antenna array of the present invention replaces traditional communication antennas used for direction finders, such as dipole antennas and Yagi antennas, which extend in the axial direction, by using a method of conformally attaching patch antennas to conventional direction finders, thereby greatly reducing the cross-sectional height of the antenna; by adjusting the width parameters of the resonant cavity, the matching wavelength range is increased, thereby expanding the working frequency band of the antenna; a rectangular patch is used at the end of the radiating patch to improve the current distribution on the radiating patch, thereby improving the electromagnetic performance of the antenna; combined with its extensibility and flexibility, the volume of the antenna array when stored is reduced, the adaptability of integration in direction finder systems with different shapes is improved, the unfolded size of the direction finder when working is reduced, the flexibility of application is increased, and the cost of design and use is reduced. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a schematic diagram of the structure of the antenna unit in the flexible antenna array of the present invention. Figure 2 It is a schematic diagram of the structure of each dipole patch in the antenna unit of the present invention. Figure 3 It is the reflection characteristic of the antenna unit in the flexible antenna array of the present invention. Figure 4 Horizontal and vertical polarization radiation characteristics of the antenna units in the flexible antenna array of the present invention at different frequencies; wherein (a) is 660 MHz frequency; (b) is 1.64 GHz frequency; and (c) is 2.15 GHz frequency. Figure 5 This is a real photo of the flexible antenna array of the present invention. Figure 6 This is a physical diagram of the radio direction finding system of Example 1 of the present invention. Figure 7 This is a diagram of the direction finding results of the radio direction finding system of Example 1 of the present invention. DETAILED DESCRIPTION In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the implementation modes and the accompanying drawings. A flexible antenna array includes m×n array-arranged antenna units, the structure diagram of the antenna unit is as follows Figure 1 As shown, the antenna unit includes a flexible dielectric layer, a first radiation patch arranged on the upper surface of the dielectric layer, and a second radiation patch arranged on the lower surface of the dielectric layer; The second radiation patch is obtained by rotating the first radiation patch by 180°; the first radiation patch includes two identical radiation monopole patches, each of which is composed of a central rectangular feeding area and a radiation area; the radiation area is an irregular heptagon, one side of which is connected to the central rectangular feeding area, and a hexagonal resonant cavity is arranged inside the heptagon away from the center of the dielectric layer to achieve resonant matching of electromagnetic waves of different wavelengths, thereby achieving the purpose of broadening the working frequency band of the original dipole patch unit, and the hexagonal resonant cavity is composed of a trapezoid and a rectangle, and the lower bottom side of the trapezoid coincides with the long side of the rectangle; the rest of the radiation area except the resonant cavity is an extensible periodic grid structure; a rectangular coupling patch is also arranged at the upper bottom side of the trapezoid close to the edge of the dielectric layer, which is used to improve the current distribution in the corresponding area of the radiation monopole patch and improve the electromagnetic performance of the antenna; A radiating monopole patch in the first radiating patch and an opposite radiating monopole patch in the second radiating patch form a double dipole through a feeding interface; wherein the feeding interface includes a central rectangular feeding patch and a through hole; The flexible antenna array is connected to the feeding interface through a coaxial line for feeding. A radiating monopole patch in the first radiating patch and an opposite radiating monopole patch in the second radiating patch form a double dipole through a feeding interface, and the structure thereof is as follows: Figure 2 As shown; wherein the feed interface includes a central rectangular feed patch and a through hole; The flexible antenna array is connected to the feeding interface through a coaxial line for feeding. Example 1 The longest and widest dimensions of the radiating monopole patch are 140mm and 55mm respectively; the size of the center-fed rectangular patch is 5mm×13mm; the hexagonal resonant cavity is composed of a trapezoid and a rectangle, and the lower base of the trapezoid coincides with the long side of the rectangle; among them, the upper and lower bases of the trapezoid are 36mm and 55mm respectively, the height is 20mm, the long side of the rectangle is 55mm, and the wide side is 20mm. The hexagonal resonant cavity broadens the working bandwidth of the original dipole patch to better meet the requirements of the passive positioning system. The overall unit structure is a centrally symmetrical structure to obtain the same response characteristics to horizontally polarized and vertically polarized electromagnetic waves. The area outside the resonant cavity in the radiating monopole patch is a serpentine line with a line width of 0.1mm and a diameter of 1.6mm for the serpentine line unit. Figure 3 It is the reflection characteristic of the antenna unit in the flexible antenna array of the present invention. As can be seen from the figure, the reflection coefficients of the antenna unit under horizontal polarization and vertical polarization are basically the same and are both below -5dB. The overall reflection coefficient can meet the passive positioning needs of the LS band. Figure 4 The horizontal and vertical polarization radiation characteristics of the antenna units in the flexible antenna array of the present invention at different frequencies; among them, (a) is the 660MHz frequency; (b) is the 1.64GHz frequency; (c) is the 2.15GHz frequency. In the figure, the spherical shape represents the far-field radiation pattern, and the dBi axis uses colors to represent different gains. It can be seen from the figure that the gains of the antenna of the present invention at three frequencies are 2dBi, 6.4dBi and 2.15GHz, respectively, all greater than 2dB, which meets the actual working requirements; At the same time, the antenna has good beam characteristics (at each frequency point), and there is no obvious difference in radiation characteristics under horizontal polarization and vertical polarization conditions, avoiding distortion of direction finding results due to receiving electromagnetic waves in different polarization directions. Example 2 A radio direction finding system, the physical diagram of which is shown in Figure 6 As shown in the figure, the unfolded diameter of the direction-finding system is only 330 mm, including a flexible antenna array, a GPS antenna, a monitoring direction-finding receiver, an electronic compass, a control terminal and a power supply; The flexible antenna array includes seven independently fed antenna units, as shown in the figure below. Figure 5 As shown, the left side shows the antenna array in a folded state, and the right side shows the antenna array in an unfolded state; that is, the flexible antenna array of the present invention has good convenience and portability; The flexible antenna array is arranged along a 360° circle below the GPS antenna and electronic compass, and each antenna unit is connected to a receiving channel; The flexible antenna array is used to receive radio signals and feed the radio signals into the monitoring direction-finding receiver; the GPS antenna is used to provide geographic coordinate signals, and the electronic compass is used to provide direction information; The monitoring and direction-finding receiver performs phase analysis and solution on the radio signal in combination with the geographic coordinate signal and direction information, thereby obtaining the direction information of the incoming wave, and transmits the direction information of the incoming wave to the control terminal via Ethernet; the control terminal is used to control the equipment to perform tasks such as frequency scanning and orientation, and to visually present the positioning results. In order to verify the actual effectiveness of the system, the 101.7MHz broadcast signal transmitted by the Sichuan Radio and Television Tower was selected as the positioning target, and an actual positioning performance test was carried out. Figure 7 The actual positioning test results based on the flexible and extensible antenna array proposed in the present invention are shown. As can be seen from the figure, the positioning results displayed by the system successfully point to the location of the Sichuan Radio and Television Tower, indicating that the system can successfully complete the determination of the incoming wave direction. The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.
Claims
1. A flexible antenna array, comprising m×n antenna units arranged in an array, characterized in that: The antenna unit includes a flexible dielectric layer, a first radiation patch disposed on the upper surface of the dielectric layer, and a second radiation patch disposed on the lower surface of the dielectric layer; The second radiation patch is obtained by rotating the first radiation patch by 180°; the first radiation patch includes two identical radiation monopole patches, and each radiation monopole patch consists of a central rectangular feeding area and a radiation area; the radiation area is an irregular heptagon, one side of which is connected to the central rectangular feeding area, and a hexagonal resonance cavity is provided inside the heptagon away from the center of the dielectric layer to achieve resonance matching for electromagnetic waves of different wavelengths, so as to broaden the working frequency band of the original dipole patch unit. The hexagonal resonance cavity is composed of a trapezoid and a rectangle, and the lower bottom side of the trapezoid coincides with the long side of the rectangle; the rest of the radiation area except the resonance cavity is a stretchable periodic grid structure; a rectangular coupling patch is also provided near the edge of the dielectric layer at the upper bottom side of the trapezoid to improve the current distribution in the corresponding area of the radiation monopole patch and enhance the electromagnetic performance of the antenna; One radiation monopole patch in the first radiation patch and the opposite radiation monopole patch in the second radiation patch form a double dipole through a feeding interface; wherein, the feeding interface includes a central rectangular feeding patch and a through hole; The flexible antenna array is connected to the feeding interface through a coaxial cable for feeding.
2. The flexible antenna array according to claim 1, characterized in that: The stretchable periodic grid structure is a fractal curve, a broken line or a serpentine line.
3. The flexible antenna array according to claim 2, characterized in that: The periodic grid structure is a serpentine line, wherein the serpentine line is obtained by periodically arranging unit structures, and each unit structure is obtained by successively rotating a semi-circle by 90°, 180° and 270° with one end point as the center point, and the whole is in the shape of "卍".
4. The flexible antenna array according to claim 3, characterized in that: The width of the serpentine line is 0.1 - 0.5 mm, and the radius of the arc segment of the serpentine line is 1 - 4 mm.
5. The flexible antenna array according to claim 1, characterized in that: The materials of the first dipole patch and the second dipole patch are copper foils with a thickness of 18 μm - 35 μm.
6. The flexible antenna array according to claim 1, characterized in that: The material of the flexible dielectric layer is polydimethylsiloxane, Ecoflex or a flexible liquid crystal material.
7. The flexible antenna array according to claim 6, characterized in that: The intermediate dielectric layer is selected as a PDMS material with a thickness of 0.75 - 2 mm.
8. A radio direction finding system, characterized in that: It includes the flexible antenna array, a GPS antenna, a monitoring and direction-finding receiver, an electronic compass, a control terminal and a power supply according to any one of claims 1 - 7; The flexible antenna array is arranged along a 360° circumference below the GPS antenna and the electronic compass. The number of antenna units of the flexible antenna array is equal to the number of receiving channels of the monitoring and direction-finding receiver, and each antenna unit is connected to one receiving channel; The flexible antenna array is used to receive radio signals and feed the radio signals into the monitoring and direction-finding receiver; the GPS antenna is used to provide geographic coordinate signals, and the electronic compass is used to provide direction information; The monitoring and direction-finding receiver combines the geographic coordinate signals and the direction information to perform phase analysis and calculation on the radio signals, so as to obtain the direction information of the incoming wave, and transmit the direction information of the incoming wave to the control terminal; the control terminal is used to display the positioning result.