Tight coupling phased-array antenna unit and tight coupling phased-array antenna

Abstract

The embodiment of the invention discloses a tightly-coupled phased-array antenna unit and a tightly-coupled phased-array antenna, and relates to the technical field of communication, the antenna unit comprises a radiation structure and a feed structure, the characteristic impedance of a coplanar waveguide is mainly related to the width of a signal line and the width of a gap between the signal line and a ground wire, and the radiation structure and the feed structure are integrated. The influence of the thickness of the substrate on the characteristic impedance is small, and corresponding impedance matching and transition can also be realized by adopting the flexible thin substrate, so that the basic structure forming the antenna unit is designed based on the flexible substrate, the impedance matching is realized by arranging the index gradual change groove, the impedance matching with the SMA connector and the antenna end is conveniently realized, and the antenna performance is improved. According to the antenna, the opening size is gradually increased from the input end to the output end, good impedance transition is achieved, the matching problem of a traditional feed structure on an ultrathin substrate is solved, flexible design of the antenna is achieved, the structure is arranged on a coplanar waveguide, no extra space is occupied, and lightweight design of the antenna can be supported.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a tightly coupled phased array antenna unit and a tightly coupled phased array antenna. Background Art

[0002] With the increasing integration and functional diversification of communication systems, the need for antennas with multiple frequency bands and varying performance levels is often required within the same device. This results in a shrinking amount of space available for antenna installation, necessitating the development of wireless devices that are miniaturized and lightweight. The emergence of tightly coupled antennas can further reduce design difficulty and complexity while maintaining antenna performance. However, existing tightly coupled dipole antenna arrays often require a complex balun feed structure, making their design difficult to apply to flexible, ultra-thin substrates, hindering flexibility and lightweighting. Summary of the Invention

[0003] The main purpose of this application is to provide a tightly coupled phased array antenna unit and a tightly coupled phased array antenna, aiming to solve the problem in the prior art that tightly coupled antenna arrays are not conducive to flexibility and lightweight.

[0004] The technical solutions adopted in this application are as follows: A tightly coupled phased array antenna unit, comprising: A radiation structure is provided on the first flexible substrate; The feeding structure includes a coplanar waveguide and a reflective floor, wherein: the coplanar waveguide is arranged on a second flexible substrate, the reflective floor is coaxial with the first flexible substrate, the second flexible substrate is vertically arranged between the reflective floor and the first flexible substrate, and the output end of the feeding structure is coupled with the radiating structure, and the input end of the feeding structure is coupled with the reflective floor; the coplanar waveguide is provided with an exponential gradient groove, and the opening size of the exponential gradient groove gradually increases from the input end of the feeding structure to the output end of the feeding structure.

[0005] Optionally, the radiating structure includes: Dipole antenna arms arranged opposite to each other; The parasitic metal strip is arranged on the side of the dipole antenna arm and extends in the same direction as the dipole antenna arm.

[0006] Optionally, the radiation structure further includes a coupling metal sheet, which is arranged at one end of the dipole antenna arm that is away from each other, and extends in a direction perpendicular to the dipole antenna arm.

[0007] Optionally, the ends of the dipole antenna arms that are close to each other adopt an asymmetric structure, and one dipole antenna arm is connected to the signal line of the coplanar waveguide, and the other dipole antenna arm is connected to the ground line of the coplanar waveguide.

[0008] Optionally, the tightly coupled phased array antenna unit further includes a wide-angle matching layer, which is coupled to the radiation structure and includes a third flexible substrate and a first metal strip printed on the third flexible substrate.

[0009] Optionally, the wide-angle matching layer further includes a fourth flexible substrate, the third flexible substrate is parallel to the radiation structure, the fourth flexible substrate is vertically arranged between the third flexible substrate and the radiation structure, a second metal strip is printed on the fourth flexible substrate, and an extension direction of the second metal strip is perpendicular to the first metal strip.

[0010] Optionally, a short stub is provided on the coplanar waveguide, and the short stub is used to connect the ground wires on both sides of the coplanar waveguide.

[0011] Optionally, a rectangular groove is provided on the reflective floor, and a plug-in portion matching the rectangular groove is provided on the bottom of the second flexible substrate, and the plug-in portion extends into the rectangular groove.

[0012] Optionally, the feeding structure further includes an SMA connector pad, which is close to the input end of the feeding structure and is used to connect to the SMA connector.

[0013] To achieve the above-mentioned objectives, an embodiment of the present application further provides a tightly coupled phased array antenna, comprising a plurality of tightly coupled phased array antenna units arranged in an array as provided in an embodiment of the present application.

[0014] Compared with the prior art, the present invention has the following advantages: The embodiments of the present application propose a tightly coupled phased array antenna unit and a tightly coupled phased array antenna, which include a radiation structure and a feeding structure. Since the characteristic impedance of the coplanar waveguide is mainly related to the signal line width and the width of the gap between the signal line and the ground line, the thickness of the substrate has little effect on its characteristic impedance. The corresponding impedance matching and transition can also be achieved using a flexible thin substrate. Therefore, the basic structure of the antenna unit is designed based on the flexible substrate, and the impedance matching is achieved by setting an exponential gradient groove, which is convenient for impedance matching with the SMA connector and the antenna end. The opening size gradually increases from the input end to the output end, achieving a good impedance transition, overcoming the matching difficulty of the traditional feeding structure on the ultra-thin substrate, and realizing a flexible antenna design. Moreover, this structure is set on the coplanar waveguide and does not occupy additional space, which can support the lightweight design of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the overall structure of a tightly coupled phased array antenna unit provided in an embodiment of the present application; Figure 2 An exploded view of a tightly coupled phased array antenna unit provided in an embodiment of the present application; Figure 3A schematic diagram of the front structure of the second flexible substrate in the tightly coupled phased array antenna unit provided in an embodiment of the present application; Figure 4 A schematic diagram of the back structure of the second flexible substrate in the tightly coupled phased array antenna unit provided in an embodiment of the present application; Figure 5 A schematic diagram of the structure of the radiation structure in the tightly coupled phased array antenna unit provided in an embodiment of the present application; Figure 6 A schematic diagram of the structure of a wide-angle matching layer in a tightly coupled phased array antenna unit provided in an embodiment of the present application; Figure 7 A schematic diagram of the active standing wave ratio of the analog port of the tightly coupled phased array antenna unit provided in an embodiment of the present application; Numbers in the figure: 1-third flexible substrate, 2-fourth flexible substrate, 3-dipole antenna arm, 4-coplanar waveguide, 5-reflection floor, 6-stub, 7-SMA connector pad, 8-coupling metal sheet, 9-parasitic metal strip. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0017] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0018] As communication systems become increasingly integrated and functionally diverse, the need for antennas with multiple frequency bands and varying performance is often required within the same device. This results in less and less space available for antenna installation, necessitating the development of wireless devices that are increasingly smaller and lighter. Simply employing multiple independent antennas operating in different frequency bands often fails to meet user needs. However, the emergence of ultra-wideband phased array antennas can effectively overcome this challenge. Using a single antenna array, an ultra-wideband phased array antenna can achieve the same performance as multiple antenna arrays operating in different frequency bands and covering different areas. This significantly reduces the system's size, weight, and cost, greatly expanding the antenna's application scenarios.

[0019] Traditional ultra-wideband phased arrays still face various operational challenges, making them difficult to meet the stringent space, weight, and performance requirements of some modern electronic devices, such as aircraft and satellites. The emergence of ultra-wideband, ultra-wide-angle scanning phased array antennas has further improved antenna performance. These antennas can cover a larger scanning volume with fewer antennas, further reducing the number of antennas required, lowering system design complexity and complexity, and improving system stability. Currently, mainstream ultra-wideband, ultra-wide-angle scanning phased array antennas include slot antennas (Vivaldi antennas) and tightly coupled antenna arrays (TCAs). Slot antennas sacrifice profile height in exchange for increased operating bandwidth, which often results in a profile height that is unsuitable for wide bandwidth applications. Tightly coupled arrays (TCAs), developed from connected arrays, achieve low profiles and wide-angle scanning with wide-angle matching (WAIM). However, conventional tightly coupled dipole antenna arrays often require a complex balun feeding structure, which makes their design complex and difficult to apply to flexible ultra-thin substrates (impedance matching is difficult), which is not conducive to flexibility and lightweight.

[0020] Existing tightly coupled dipole antenna arrays are limited by the complexity of feeding. Most use baluns with millimeter-thick substrates. Some also use a microstrip line-to-dual line structure printed on a thin substrate for feeding. However, this design requires an extremely narrow line width (generally less than 100 microns), which poses great challenges to the processing technology and makes it difficult to ensure the stability of the finished product. Therefore, there are few tightly coupled antennas that are flexible, lightweight, and easy to process.

[0021] For example, patent application publication number CN114221116 A proposes a flexible, ultra-thin, modular, ultra-wideband tightly coupled array antenna. This antenna comprises a radiating layer, a supporting layer, a high-resistance layer, a floor layer, and several feed coaxial lines. It suffers from low radiation efficiency, high cost, complex assembly, and difficulty in lightweighting. Another example is patent application publication number CN114006165A, which proposes an ultra-wideband tightly coupled antenna array that uses a resistor sheet to extend bandwidth. This antenna structure comprises two dielectric substrates, a resistor sheet, and a metal block. A single antenna unit consists of a radiating dipole and a feed balun; the radiating dipole and balun are connected by metal vias, and the resistor sheet is placed between the metal block and the dipole. However, this antenna structure is bulky and cannot be made flexible and lightweight.

[0022] To solve the above problems, refer to the attached Figure 1 -Attached Figure 6 An embodiment of the present application provides a tightly coupled phased array antenna unit, comprising: a radiating structure and a feeding structure, wherein the radiating structure is disposed on a first flexible substrate, and the feeding structure comprises a coplanar waveguide 4 and a reflective floor 5, wherein: the coplanar waveguide 4 is disposed on a second flexible substrate, the reflective floor 5 is coaxial with the first flexible substrate, and the second flexible substrate is disposed perpendicularly between the reflective floor 5 and the first flexible substrate, so that the output end of the feeding structure is coupled to the radiating structure, and the input end of the feeding structure is coupled to the reflective floor 5, and the coplanar waveguide 4 is provided with an exponentially tapered groove, and the opening size of the exponentially tapered groove gradually increases from the input end of the feeding structure to the output end of the feeding structure.

[0023] In this embodiment, the antenna unit includes a radiation structure and a feeding structure. Since the characteristic impedance of the coplanar waveguide 4 is mainly related to the signal line width and the width of the gap between the signal line and the ground line, the thickness of the substrate has little effect on its characteristic impedance. The corresponding impedance matching and transition can also be achieved by using a flexible thin substrate. Therefore, the basic structure of the antenna unit is designed based on the flexible substrate, and the impedance matching is achieved by setting an exponential gradient groove, which is convenient for impedance matching with the SMA connector and the antenna end. The opening size gradually increases from the input end to the output end to achieve a good impedance transition, overcome the matching problem of the traditional feeding structure on the ultra-thin substrate, and realize the flexible design of the antenna. Moreover, this structure is set on the coplanar waveguide 4 and does not occupy additional space, which can support the lightweight design of the antenna.

[0024] The coplanar waveguide 4 can be printed on a single surface of a 50-micron-thick PI flexible substrate, using an 18-micron-thick printed copper layer. The input port of the feed structure has a characteristic impedance of 50 ohms, and an external solder pad structure is retained to facilitate impedance matching with the SMA connector. Specifically, the feed structure also includes an SMA connector solder pad 7, which is located near the input end of the feed structure and is used to connect to the SMA connector. The output end has a characteristic impedance of 90 ohms, which facilitates impedance matching with the antenna end. The coplanar waveguide feed structure, SMA connector, and antenna are all soldered to ensure stable electrical connections. The ground wire can achieve common-mode suppression. Ultra-wideband impedance matching is achieved by adjusting the length and gradient coefficient of the exponential gradient.

[0025] In one embodiment, as shown in the attached Figure 5 As shown, the radiating structure includes a dipole antenna arm 3 and a parasitic metal strip 9. The dipole antenna arms 3 are positioned opposite each other; the parasitic metal strip 9 is positioned to the side of the dipole antenna arm 3 and extends in the same direction as the dipole antenna arm 3. The dipole antenna is the earliest, simplest, and most widely used type of antenna in radio communications. It consists of a pair of symmetrically placed conductors, each connected to a feeder line at its adjacent ends. When used as a transmitting antenna, electrical signals are fed into the conductors from the center of the antenna. When used as a receiving antenna, signals are received from the conductors at the same location. The parasitic metal strip 9 can extend the antenna's impedance bandwidth by introducing additional resonant modes. It can also improve the antenna's radiation pattern and directivity, thereby increasing antenna gain and enabling miniaturization and compactness. Adjusting the size and position of the parasitic metal strip 9 can also improve the antenna's impedance matching, enabling better matching with the transmission line and reducing reflections and losses.

[0026] In one embodiment, as shown in the attached Figure 5 As shown, the radiating structure further includes a coupling metal sheet 8, which is disposed at the ends of the dipole antenna arms 3 that are spaced apart from each other and extends perpendicularly to the dipole antenna arms 3. As described in the above embodiment, the coupling metal sheet 8 is used to enhance coupling. By increasing the coupling area and optimizing the electromagnetic field distribution, it significantly improves the coupling effect between adjacent antenna elements, overcoming the performance degradation caused by insufficient coupling in traditional designs and further enhancing the overall radiation efficiency and bandwidth performance of the antenna.

[0027] In one embodiment, the ends of the dipole antenna arms 3 that are close to each other adopt an asymmetric structure, and one dipole antenna arm 3 is connected to the signal line of the coplanar waveguide 4, and one dipole antenna arm 3 is connected to the ground line of the coplanar waveguide 4. Figure 5As shown, the ends of the dipole antenna arms 3 that are close to each other are respectively set to be trapezoidal and rectangular. In order to avoid short circuit, an arc groove is set at one end of the rectangle. This asymmetric structure overcomes the characteristic that the traditional symmetrical structure cannot be connected to the asymmetric coplanar band, and realizes convenient connection.

[0028] In one embodiment, as shown in the attached Figure 1 and attached Figure 2 The tightly coupled phased array antenna unit further includes a wide-angle matching layer, which is coupled to the radiating structure and includes a third flexible substrate 1 and a first metal strip printed on the third flexible substrate. As in the above embodiment, frequency selection is achieved by designing a wide-angle matching layer. The wide-angle matching layer is located above the antenna radiating structure and has the effect of transitioning the antenna impedance and the free space impedance. Furthermore, the attached Figure 6 As shown, the wide-angle matching layer further includes a fourth flexible substrate 2. The third flexible substrate 1 is parallel to the radiating structure. The fourth flexible substrate 2 is vertically arranged between the third flexible substrate 1 and the radiating structure. A second metal strip is printed on the fourth flexible substrate 2. The extension direction of the second metal strip is perpendicular to the first metal strip.

[0029] As shown in the above implementation, the wide-angle matching layer consists of vertical and horizontal metal strips, each printed on a 50-micron-thick PI flexible substrate. The vertical metal strips compensate for the horizontal strips, optimizing the antenna's impedance matching performance at high frequencies. This overcomes the degradation of high-frequency matching performance seen in traditional antennas during wide-angle scanning, significantly enhancing the antenna's wide-angle scanning capabilities.

[0030] In one embodiment, as shown in the attached Figure 4 As shown, a stub 6 is provided on the coplanar waveguide 4, and the stub 6 is used to connect the ground wires on both sides of the coplanar waveguide 4. As in the above embodiment, the stub 6 can be provided on the back side of the second flexible substrate to connect the two ground wires of the coplanar waveguide 4, thereby ensuring the stability of the electrical connection.

[0031] In one embodiment, as shown in the attached Figure 1 , Attachment Figure 2 As shown, a rectangular groove is defined in the reflective floor panel 5. A plug-in portion is provided at the bottom of the second flexible substrate, matching the groove and extending into the groove. As described above, the design of the rectangular groove and the plug-in portion ensures a stable coupling connection between the second flexible substrate and the reflective floor panel 5, while also preventing short circuits in the signal lines of the coplanar waveguide 4.

[0032] As attached Figure 7 As shown, a schematic diagram of the active standing wave ratio of the analog port of the tightly coupled phased array antenna unit provided by an embodiment of the present application is shown, wherein: within 1-7.8 GHz, the active standing wave ratio is less than 3 when the E-plane scans ±60°, less than 4 when the H-plane scans ±45°, and less than 6 when the H-plane scans ±60°.

[0033] Based on the same inventive concept as the aforementioned embodiment, the present embodiment further provides a tightly coupled phased array antenna, comprising a plurality of tightly coupled phased array antenna units, such as those provided in the present embodiment, arranged in an array. As described above, by combining antenna units to form a phased array antenna, a tightly coupled dipole antenna array with a flexible and lightweight design is obtained. This ensures excellent antenna performance while maintaining a simple and easily designed feed structure. The beneficial effects of the present embodiment can be referenced to the aforementioned embodiment and are not further elaborated here.

[0034] In summary, the embodiments of the present application provide a tightly coupled phased array antenna unit and a tightly coupled phased array antenna, which include a radiation structure and a feeding structure. Since the characteristic impedance of the coplanar waveguide is mainly related to the signal line width and the width of the gap between the signal line and the ground line, the thickness of the substrate has little effect on its characteristic impedance. The corresponding impedance matching and transition can also be achieved using a flexible thin substrate. Therefore, the basic structure of the antenna unit is designed based on the flexible substrate, and the impedance matching is achieved by setting an exponential gradient groove, which is convenient for impedance matching with the SMA connector and the antenna end. The opening size gradually increases from the input end to the output end, achieving a good impedance transition, overcoming the matching problem of the traditional feeding structure on the ultra-thin substrate, and realizing the flexible design of the antenna. Moreover, this structure is set on the coplanar waveguide and does not occupy additional space, which can support the lightweight design of the antenna.

[0035] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A tightly coupled phased array antenna unit, characterized in that: include: A radiation structure is provided on the first flexible substrate; A feeding structure includes a coplanar waveguide and a reflective floor, wherein: the coplanar waveguide is arranged on a second flexible substrate, the reflective floor is coaxial with the first flexible substrate, and the second flexible substrate is vertically arranged between the reflective floor and the first flexible substrate, so that the output end of the feeding structure is coupled with the radiating structure and the input end of the feeding structure is coupled with the reflective floor; the coplanar waveguide is provided with an exponentially tapered groove, and the opening size of the exponentially tapered groove gradually increases from the input end of the feeding structure to the output end of the feeding structure.

2. The tightly coupled phased array antenna unit according to claim 1, wherein: The radiation structure comprises: Dipole antenna arms arranged opposite to each other; The parasitic metal strip is arranged on the side of the dipole antenna arm and extends in the same direction as the dipole antenna arm.

3. The tightly coupled phased array antenna unit according to claim 2, wherein: The radiation structure further includes a coupling metal sheet, which is arranged at one end of the dipole antenna arm that is away from each other and extends in a direction perpendicular to the dipole antenna arm.

4. The tightly coupled phased array antenna unit according to claim 2, wherein: The ends of the dipole antenna arms that are close to each other adopt an asymmetric structure, and one of the dipole antenna arms is connected to the signal line of the coplanar waveguide, and the other of the dipole antenna arms is connected to the ground line of the coplanar waveguide.

5. The tightly coupled phased array antenna unit according to claim 1, wherein: The tightly coupled phased array antenna unit further includes a wide-angle matching layer, which is coupled to the radiation structure and includes a third flexible substrate and a first metal strip printed on the third flexible substrate.

6. The tightly coupled phased array antenna unit according to claim 5, characterized in that: The wide-angle matching layer further includes a fourth flexible substrate. The third flexible substrate is parallel to the radiation structure. The fourth flexible substrate is vertically arranged between the third flexible substrate and the radiation structure. A second metal strip is printed on the fourth flexible substrate. The extension direction of the second metal strip is perpendicular to the first metal strip.

7. The tightly coupled phased array antenna unit according to claim 1, wherein: A short stub is provided on the coplanar waveguide, and the short stub is used to connect the ground wires on both sides of the coplanar waveguide.

8. The tightly coupled phased array antenna unit according to claim 1, wherein: A rectangular groove is provided on the reflective floor, and a plug-in portion matching the rectangular groove is provided at the bottom of the second flexible substrate, and the plug-in portion extends into the rectangular groove.

9. The tightly coupled phased array antenna unit according to claim 1, wherein: The feeding structure further includes an SMA connector pad, which is close to the input end of the feeding structure and is used to be connected to the SMA connector.

10. A tightly coupled phased array antenna, characterized in that: The invention comprises a plurality of tightly coupled phased array antenna units according to any one of claims 1 to 9 arranged in an array.

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