A phased array antenna with a folded back cavity structure

Abstract

The present invention discloses a phased array antenna with a folded cavity-backed structure, comprising at least two electrically connected phased array antenna units, each comprising a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, and a differential feed network layer stacked in sequence; a first resonant cavity and a second resonant cavity are formed between the first and second metal layers, a third resonant cavity is formed between the second and third metal layers, the first and second resonant cavities are stacked on the third resonant cavity, and the first and second resonant cavities are respectively connected to the third resonant cavity; two radiating slots are respectively formed on both side edges of the first metal layer, the two radiating slots are respectively connected to the corresponding two resonant cavities; and the differential feed network layer is electrically connected to the second metal layer. By folding the resonant cavity, the present invention can save structural space, meet the design requirements of compact structure and miniaturization, and simultaneously achieve wide-angle scanning.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a phased array antenna with a folded cavity-back structure. Background Art

[0002] Phased array antennas offer rapid beam scanning capabilities, overcoming the slow speed and low precision of traditional mechanical beam scanning arrays. Consequently, they have attracted considerable attention in both academic and commercial fields. With the rapid development and widespread adoption of 5G and wireless technologies, performance metrics such as scanning range, compactness, and stability have become key indicators of phased array antenna quality.

[0003] In order to improve the scanning coverage of phased array antennas, most existing solutions use wide-beam antenna units or reconfigurable pattern units to construct phased arrays. For example, Mei Li et al. proposed a wide-angle scanning phased array in "Investigation of Using High Impedance Surfaces for Wide-Angle Scanning Arrays[J]. IEEE Transactions on Antennas and Propagation, 2015, 63(7):2895-2901", which uses high-impedance surface-conducted surface waves to achieve the effect of widening the beam width. In the above solution, a 1×8 wide-angle scanning phased array unit is finally formed based on the high-impedance surface. The scanning angle range covers from -85° to 85°, and the gain in the maximum gain direction reaches 13.8dBi. At the same time, the gain in the maximum scanning angle direction reaches 10.9dBi, which is less than 3dBi lower than the maximum gain. At the same time, the sidelobe level is always less than the maximum gain -10dB throughout the scanning range. However, the above solution requires the use of a high-impedance surface, which increases the overall height of the phased array antenna and does not meet the design requirements of compact structure and miniaturization.

[0004] In view of this, it is necessary to further improve the structure of the current phased array antenna. Summary of the Invention

[0005] In order to solve at least one of the above technical problems, the main purpose of the present invention is to provide a phased array antenna with a folded cavity-backed structure.

[0006] To achieve the above objectives, the present invention adopts a technical solution as follows: providing a phased array antenna with a folded cavity-backed structure, comprising at least two electrically connected phased array antenna units, wherein the phased array antenna units include a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, and a differential feed network layer stacked in sequence;

[0007] A first resonant cavity and a second resonant cavity are formed between the first metal layer and the second metal layer, and a third resonant cavity is formed between the second metal layer and the third metal layer. The first resonant cavity and the second resonant cavity are respectively stacked on the third resonant cavity, and the first resonant cavity and the second resonant cavity are respectively communicated with the third resonant cavity.

[0008] A first radiation slot corresponding to the first resonant cavity is formed on one side edge of the first metal layer, and the first radiation slot is connected to the first resonant cavity; a second radiation slot corresponding to the second resonant cavity is formed on the other side edge of the first metal layer, and the second radiation slot is connected to the second resonant cavity;

[0009] The differential feeding network layer is electrically connected to the second metal layer, and the differential feeding network layer is used to feed radio frequency energy into the resonant cavity composed of the first resonant cavity, the second resonant cavity and the third resonant cavity, and output the radio frequency energy received by the resonant cavity composed of the first resonant cavity, the second resonant cavity and the third resonant cavity.

[0010] The periphery of the first metal layer has a plurality of first metal vias arranged at intervals, and the first metal vias sequentially penetrate the first metal layer, the first dielectric layer, the second dielectric layer and the third metal layer, and the third resonant cavity is formed in the enclosed space of the second metal layer, the third metal layer and the first metal vias;

[0011] The second metal layer has a plurality of second metal vias and a third metal via connected to the first metal layer on opposite side edges, the second metal vias sequentially passing through one side of the first dielectric layer and the second metal layer, and the first resonant cavity is formed in the enclosed space of the first metal layer, the second metal layer, the first metal vias, and the second metal vias;

[0012] The third metal via sequentially penetrates the first dielectric layer and the other side of the second metal layer, and the second resonant cavity is formed in the enclosed space of the first metal layer, the second metal layer, the first metal via and the third metal via.

[0013] The diameters of the first metal via, the second metal via and the third metal via are all 0.002λ0~0.007λ0, and the hole center spacings between adjacent first metal vias, second metal vias and third metal vias are all 2.5-3 times the metal via diameters, where λ0 is the free space wavelength.

[0014] Among them, the first radiation slot and the second radiation slot are symmetrically distributed and are both long strip openings extending along the width direction of the first metal layer. The lengths of the first radiation slot and the second radiation slot are both 0.16λ0~0.18λ0, and the widths are both 0.006λ0~0.02λ0; the spacing between the first radiation slot and the second radiation slot is 0.17λ0~0.2λ0, wherein λ0 is the free space wavelength.

[0015] The length and width of the first metal layer are both 0.23λ0-0.26λ0, the length and width of the second metal layer are both 0.18λ0-0.21λ0, and two ends of the first metal layer extend out of two ends of the second metal layer respectively; the length of the third metal layer is 0.23λ0-0.34λ0, and the width is 0.23λ0-0.26λ0, and two ends of the third metal layer extend out of two ends of the second metal layer respectively;

[0016] The thickness of the first dielectric layer and the second dielectric layer is 0.03λ0-0.05λ0, and the length and width of the first dielectric layer and the second dielectric layer are both 0.28λ0-0.34λ0, where λ0 is a free space wavelength.

[0017] It also includes a third dielectric layer located between the third metal layer and the differential feed network layer. The differential feed network layer is arranged on the third dielectric layer. The thickness of the third dielectric layer is 0.01λ0~0.02λ0, and the length and width of the third dielectric layer are both 0.28λ0~0.34λ0, where λ0 is the free space wavelength.

[0018] Among them, the differential feeding network layer includes a welding pad, a feeding network and a feeding coaxial probe, the welding pad is electrically connected to the feeding network, the feeding network is electrically connected to the feeding coaxial probe, the feeding coaxial probe passes through the third dielectric layer, the third metal layer, the second dielectric layer and the second metal layer in sequence, and the feeding coaxial probe is electrically connected to the second metal layer.

[0019] The feed network includes a first power splitter line electrically connected to the welding pad, and a second power splitter line electrically connected to the first power splitter line, wherein the first power splitter line has a characteristic impedance of 50Ω and a width of 0.68mm-0.78mm; the second power splitter line is bent and has a characteristic impedance of 100Ω and a width of 0.1mm-0.14mm;

[0020] The second power dividing line has a first parallel branch and a second parallel branch. The width of the first parallel branch and the second parallel branch are both 0.1 mm-0.14 mm, and the length of the first parallel branch and the second parallel branch are both 2.02 mm-2.52 mm.

[0021] Wherein, a decoupling structure arranged in a bent shape is connected between adjacent phased array antenna units.

[0022] The spacing between adjacent phased array antenna units is 0.4λ0~0.47λ0, where λ0 is the free space wavelength.

[0023] The technical solution of the present invention includes multiple adjacent phased array antenna units, each of which includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, and a differential feed network layer. A symmetrically arranged first resonant cavity and a second resonant cavity are formed between the first metal layer and the second metal layer, and a third resonant cavity is formed between the second metal layer and the third metal layer. The first resonant cavity and the second resonant cavity are respectively superimposed on the third resonant cavity and are each connected to the third resonant cavity, resulting in a folded resonant cavity structure that can save structural space and meet design requirements for compact structure and miniaturization. The first metal layer has a first radiation slot and a second radiation slot, and the differential feed network layer is electrically connected to the second metal layer. During RF transmission, the RF energy to be transmitted is fed into the folded resonant cavity through the differential feed network layer, and forms an electromagnetic resonance in the resonant cavity. It is then radiated out through the first radiation slot and the second radiation slot of the first metal layer, forming an electromagnetic wave that propagates in free space. During RF reception, the electromagnetic wave in free space enters the folded resonant cavity through the first radiation slot and the second radiation slot, and forms an electromagnetic resonance in the folded resonant cavity. It is then output to the external port through the differential feed network layer electrically connected to the second metal layer. In addition, this solution has multiple phased array antenna units. By selecting feeds with different excitation phases in different ports, the scanning angle of the phased array antenna can be changed to achieve wide-angle scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 This is a schematic diagram of the exploded structure of a phased array antenna with a folded cavity-backed structure according to one embodiment of the present invention;

[0026] Figure 2 Schematic diagram of the exploded structure of a phased array antenna unit according to an embodiment of the present invention;

[0027] Figure 3 A schematic structural diagram of a folded resonant cavity according to an embodiment of the present invention;

[0028] Figure 4 A top view of a first metal layer according to an embodiment of the present invention;

[0029] Figure 5 is a top view of the second metal layer according to an embodiment of the present invention;

[0030] Figure 6 is a top view of the third metal layer according to an embodiment of the present invention;

[0031] Figure 7 A top view of a differential feed network layer according to an embodiment of the present invention;

[0032] Figure 8 for Figure 2 S11 parameter curve corresponding to the phased array antenna unit;

[0033] Figure 9 for Figure 1 The curve of reflection coefficient and frequency in the S parameter corresponding to the phased array antenna;

[0034] Figure 10 for Figure 1 The curve of coupling coefficient and frequency in the S parameter corresponding to the phased array antenna;

[0035] Figure 11 is the scanning pattern of the phased array antenna of the present invention.

[0036] Description of labels:

[0037] 100. Phased array antenna unit:

[0038] 110, first metal layer, 111, first radiation slot, 112, second radiation slot, 113, first metal via;

[0039] 120, second metal layer, 121, second metal via, 122, third metal via, 123, feed connection hole;

[0040] 130, third metal layer, 131, feed avoidance hole;

[0041] 140. Differential feed network layer, 141. Welding pad, 142. Feed network, 143. Feed coaxial probe, 1421. First power distribution line, 1422. Second power distribution line, 1423. First parallel branch, 1424. Second parallel branch;

[0042] 151, first dielectric layer, 152, second dielectric layer, 153, third dielectric layer, 161, first resonant cavity, 162, second resonant cavity, 163, third resonant cavity;

[0043] 200. Decoupled structure.

[0044] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] It should be noted that the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is 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 the present invention.

[0047] Unlike related art phased array antennas that require high-impedance surfaces to achieve wide-angle scanning, which increases the overall height of the phased array antenna and fails to meet design requirements for compactness and miniaturization, the present invention provides a phased array antenna with a folded cavity-back structure. By folding the resonant cavity, this design saves structural space, meets design requirements for compactness and miniaturization, and simultaneously enables variable scanning angles to achieve wide-angle scanning. For the specific structure of this folded cavity-back structure phased array antenna, please refer to the following embodiments.

[0048] Please refer to Figures 1 to 7 , Figure 1 This is a schematic diagram of the exploded structure of a phased array antenna with a folded cavity-backed structure according to one embodiment of the present invention; Figure 2 Schematic diagram of the exploded structure of a phased array antenna unit according to an embodiment of the present invention; Figure 3 A schematic structural diagram of a folded resonant cavity according to an embodiment of the present invention; Figure 4 A top view of a first metal layer according to an embodiment of the present invention; Figure 5 is a top view of the second metal layer according to an embodiment of the present invention; Figure 6 is a top view of the third metal layer according to an embodiment of the present invention; Figure 7This is a top view of the differential feeding network layer of an embodiment of the present invention. In an embodiment of the present invention, the phased array antenna of the folded back cavity structure includes at least two electrically connected phased array antenna units 100. Specifically, the number of phased array antenna units 100 is eight, and they are distributed in rows or columns. Adjacent phased array antenna units 100 are electrically connected. At the same time, considering that the spacing between adjacent phased array antenna units 100 becomes smaller, the coupling between the phased array antenna units 100 also becomes larger, and a decoupling unit can be added between adjacent phased array antenna units 100 to reduce the coupling between the phased array antenna units 100. Since this solution has multiple phased array antenna units 100, by selecting feeding with different excitation phases in different ports, the scanning angle of the phased array antenna is changed to achieve wide-angle scanning.

[0049] The phased array antenna unit 100 includes a first metal layer 110, a first dielectric layer 151, a second metal layer 120, a second dielectric layer 152, a third metal layer 130 and a differential feed network layer 140 which are stacked in sequence;

[0050] A first resonant cavity 161 and a second resonant cavity 162 are formed between the first metal layer 110 and the second metal layer 120. A third resonant cavity 163 is formed between the second metal layer 120 and the third metal layer 130. The first resonant cavity 161 and the second resonant cavity 162 are stacked on the third resonant cavity 163, and the first resonant cavity 161 and the second resonant cavity 162 are communicated with the third resonant cavity 163.

[0051] A first radiation slot 111 corresponding to the first resonant cavity 161 is formed on one side edge of the first metal layer 110, and the first radiation slot 111 is connected to the first resonant cavity 161. A second radiation slot 112 corresponding to the second resonant cavity 162 is formed on the other side edge of the first metal layer 110, and the second radiation slot 112 is connected to the second resonant cavity 162.

[0052] The differential feed network layer 140 is electrically connected to the second metal layer 120 . The differential feed network layer 140 is used to feed radio frequency energy into the resonant cavity composed of the first resonant cavity 161 , the second resonant cavity 162 , and the third resonant cavity 163 , and output the radio frequency energy received by the resonant cavity composed of the first resonant cavity 161 , the second resonant cavity 162 , and the third resonant cavity 163 .

[0053] In this embodiment, the phased array antenna unit 100 is divided from top to bottom into a first metal layer 110, a first dielectric layer 151, a second metal layer 120, a second dielectric layer 152, a third metal layer 130, and a differential feed network layer 140. The materials of the first and second dielectric layers 151, 152 can be Ferro-A6M, air, FR4, etc. A symmetrical first resonant cavity 161 and a second resonant cavity 162 are formed between the first and second metal layers 110, 120. A third resonant cavity 163 is formed between the second and third metal layers 120, 130. The first and second resonant cavities 161, 162 are stacked above and communicate with the third resonant cavity 163, respectively. This means that the resonant cavity in this embodiment is a double-layer resonant cavity. This double-layer resonant cavity structure achieves a folded resonant cavity design, resulting in a smaller footprint and a more compact structure, meeting miniaturization requirements. The size of the double-layer resonant cavity is adjustable, thereby adjusting the resonant frequency of the RF energy. The shapes of the first metal layer 110, the second metal layer 120, and the third metal layer 130 can be rectangular, circular, elliptical, triangular, etc., and the specific shapes can be designed according to actual requirements. The shapes of the first dielectric layer 151 and the second dielectric layer 152 are both adapted to the shape of the first metal layer 110. In addition, the area of the second metal layer 120 is smaller than that of the first metal layer 110 and the third metal layer 130. During assembly, the outer circles of the first metal layer 110 and the third metal layer 130 cover the second metal layer 120. That is, gaps are left around the edges of the second metal layer 120, through which the first dielectric layer 151 and the second dielectric layer 152 are connected to form an integrated resonant cavity. The first radiation slot 111 and the second radiation slot 112 are both elongated openings. Through the first radiation slot 111 and the second radiation slot 112, the radio frequency energy in the double-layer resonant cavity is converted into electromagnetic waves radiated to the external space. The differential feeding network layer 140 is electrically connected to the second metal layer 120 and can feed the double-layer resonant cavity to form electromagnetic resonance.

[0054] When implementing RF transmission, RF energy is transmitted to the second metal layer 120 through the differential feeding network layer 140, fed into the first resonant cavity 161, the second resonant cavity 162 and the third resonant cavity 163, and forms electromagnetic resonance in the cavity, and then radiates out from the first radiation slot 111 and the first radiation slot 111 on the first metal layer 110, forming an electromagnetic wave propagating in free space; when implementing RF reception, the electromagnetic wave in the free space enters the first resonant cavity 161, the second resonant cavity 162 and the third resonant cavity 163 through the first radiation slot 111 and the second radiation slot 112, and forms electromagnetic resonance in the cavity, and then is output to the external port through the differential feeding network layer 140 electrically connected to the second metal layer 120.

[0055] In a specific embodiment, the periphery of the first metal layer 110 has a plurality of first metal vias 113 spaced apart from each other. The first metal vias 113 sequentially penetrate the first metal layer 110, the first dielectric layer 151, the second dielectric layer 152, and the third metal layer 130. The third resonant cavity 163 is formed in the enclosed space between the second metal layer 120, the third metal layer 130, and the first metal vias 113.

[0056] The second metal layer 120 has a plurality of second metal vias 121 and a third metal via 122 connected to the first metal layer 110 on opposite sides thereof. The second metal vias 121 sequentially penetrate the first dielectric layer 151 and one side of the second metal layer 120. The first resonant cavity 161 is formed in the enclosed space of the first metal layer 110, the second metal layer 120, the first metal vias 113, and the second metal vias 121.

[0057] The third metal via 122 sequentially penetrates the first dielectric layer 151 and the other side of the second metal layer 120. The second resonant cavity 162 is formed in the space enclosed by the first metal layer 110, the second metal layer 120, the first metal via 113, and the third metal via 122. The first metal via 113 connects the first metal layer 110 to the third metal layer 130, while the second metal via 121 and the third metal via 122 connect the first metal layer 110 to the second metal layer 120. The multiple first metal vias 113 are arranged in a rectangular shape. The second metal vias 121 and the third metal vias 122 are symmetrically arranged, and the multiple second metal vias 121 and the third metal vias 122 are arranged in rows or columns.

[0058] In one specific embodiment, the diameters of the first metal via 113, the second metal via 121, and the third metal via 122 are all 85 μm to 254 μm, corresponding to 0.002λ0 to 0.007λ0. The center-to-center spacing between adjacent first metal vias 113, second metal vias 121, and third metal vias 122 is 2.5 to 3 times the metal via diameter. The diameters of the first metal vias 113, second metal vias 121, and third metal vias 122 are limited by the low-temperature co-fired ceramic (LTCC) processing technology. The sizes of the first metal vias 113, second metal vias 121, and third metal vias 122 can be flexibly adjusted based on actual needs.

[0059] In a specific embodiment, the first and second radiation slots 111, 112 are symmetrically distributed and are both long strips extending along the width direction of the first metal layer 110. The lengths of the first and second radiation slots 111, 112 are both 5.8mm to 6.5mm, corresponding to 0.16λ0 to 0.18λ0, and the widths are both 0.2mm to 0.8mm, corresponding to 0.006λ0 to 0.02λ. The spacing between the first and second radiation slots 111, 112 is 6mm to 7.1mm, corresponding to 0.17λ0 to 0.2λ0. The symmetrical distribution of the first and second radiation slots 111, 112 allows the antenna to operate in the 8.42GHz to 8.51GHz transceiver frequency band. It is understood that different frequency band requirements can be met by designing slots of different sizes.

[0060] In a specific embodiment, the length and width of the first metal layer 110 are both 8.2 mm to 9 mm, corresponding to 0.23λ0 to 0.26λ0, the length and width of the second metal layer 120 are both 6.5 mm to 7.5 mm, corresponding to 0.18λ0 to 0.21λ0, and two ends of the first metal layer 110 extend out of two ends of the second metal layer 120 respectively. The length of the third metal layer 130 is 8.2 mm to 12 mm, corresponding to 0.23λ0 to 0.34λ0, and the width is 8.2 mm to 9 mm, corresponding to 0.23λ0 to 0.26λ0, and two ends of the third metal layer 130 extend out of two ends of the second metal layer 120 respectively.

[0061] The thickness of the first and second dielectric layers 151, 152 ranges from 0.96mm to 1.632mm, corresponding to 0.03λ0 to 0.05λ0. The length and width of the first and second dielectric layers 151, 152 are both 10mm to 12mm, corresponding to 0.28λ0 to 0.34λ0. In this embodiment, the length and width of the metal layers are approximately half a wavelength. Because the dielectric substrate used in this solution is a high-dielectric-constant material (with a dielectric constant of 5.9 and a loss tangent of 0.002), the length and width of the first metal layer 110 are adjusted. The second metal layer 120, which needs to connect the upper and lower resonant cavities, is slightly smaller than the first metal layer 110. The third metal layer 130, due to the size of the solder pad 141, is slightly longer than the first metal layer 110 and has the same width as the first metal layer 110. The thickness of both the dielectric and metal layers is limited by the LTCC process. The dielectric layer thickness must be an integer multiple of 96 μm, with a maximum of 40 layers. In the present invention, the thicknesses of the first to third metal layers 110, 130 are all between 9.73 μm and 10.3 μm, corresponding to 0.0026λ0 to 0.0029λ0. The effect of the dielectric substrate material's dielectric constant on the dielectric and metal layers is also considered. The actual thickness of the dielectric and metal layers is the square root of the free-space wavelength divided by the dielectric constant. The length and width of the first and second metal layers 110, 151, and the thickness, length, and width of the first and second dielectric layers 152 can be flexibly adjusted according to actual needs.

[0062] Taking the dielectric constant of 5.9 as an example: the thickness of the first metal layer 110 to the third metal layer 130 is 0.0026λ0-0.0029λ0, and the actual thickness is 0.0011λ d -0.0012λ d , where λ d The length and width parameters of the first metal layer 110 to the third metal layer 130 and the first dielectric layer 151 to the third dielectric layer 153 can be converted into the antenna operating wavelength. The antenna operating wavelength is related to the choice of dielectric substrate material.

[0063] Specifically, a third dielectric layer 153 is further included between the third metal layer 130 and the differential feed network layer 140. The differential feed network layer 140 is disposed on the third dielectric layer 153. The thickness of the third dielectric layer 153 is 0.384 mm to 0.576 mm, corresponding to 0.01λ0 to 0.02λ0. The length and width of the third dielectric layer 153 are both 10 mm to 12 mm, corresponding to 0.28λ0 to 0.34λ0. The thickness, length, and width of the third dielectric layer 153 can be flexibly adjusted as needed.

[0064] In a specific embodiment, the differential feed network layer 140 includes a welding pad 141, a feed network 142, and a feed coaxial probe 143. The welding pad 141 is electrically connected to the feed network 142, and the feed network 142 is electrically connected to the feed coaxial probe 143. The feed coaxial probe 143 sequentially passes through the third dielectric layer 153, the third metal layer 130, the second dielectric layer 152, and the second metal layer 120, and the feed coaxial probe 143 is electrically connected to the second metal layer 120. The welding pad 141 is connected to the SMPS port, the feed network 142 is a microstrip line, the third metal layer 130 is provided with a feed avoidance hole 131, and the second metal layer 120 is provided with a feed connection hole 123. One end of the feed coaxial probe 143 is connected to the microstrip line, and the other end passes through the feed avoidance hole 131 and is connected to the feed connection hole 123.

[0065] Specifically, the feeding network 142 includes a first power splitting line 1421 electrically connected to the welding pad 141, and a second power splitting line 1422 electrically connected to the first power splitting line 1421. The first power splitting line 1421 has a characteristic impedance of 50Ω and a width of 0.68mm-0.78mm. The second power splitting line 1422 is bent and has a characteristic impedance of 100Ω and a width of 0.1mm-0.14mm.

[0066] The second power splitter line 1422 has a first parallel branch 1423 and a second parallel branch 1424. The width of the first parallel branch 1423 and the second parallel branch 1424 are both 0.1mm-0.14mm, and the length is both 2.02mm-2.52mm. In this embodiment, the differential feed network layer 140 first connects to the SMPS port through the welding pad 141 to feed in RF energy, and then splits it into two through the power splitter line. The characteristic impedances before and after the power split are 50Ω and 100Ω, respectively. The one with a larger width has a lower characteristic impedance, and the one with a smaller width has a higher characteristic impedance. The widths of the first power splitter line 1421 and the second power splitter line 1422 can be flexibly adjusted according to needs. To achieve differential input, the two power splitter lines after the power split should differ in length by half a wavelength. Note that the half-wavelength here is not the half-wavelength of free space; the dielectric constant and thickness of the medium must be considered. The length difference in this solution ranges from 9.3 to 10 mm. The second power splitter line 1422 is folded to save space and can be folded in different ways. That is, the second power splitter line 1422 can be folded multiple times. Furthermore, a first parallel branch 1423 is connected to the second power splitter line 1422. The first parallel branch 1423 is located within and connected to the bend at one end of the second power splitter line 1422 and is parallel to the end of the second power splitter line 1422. A second parallel branch 1424 is also connected to the second power splitter line 1422 and is perpendicularly connected to the end of the second power splitter line 1422 to achieve impedance matching. The width and length of the first parallel branch 1423 and the second parallel branch 1424 can be flexibly adjusted according to needs.

[0067] Affected by the material properties of the dielectric substrate, some surface waves will propagate along the dielectric surface and radiate at the dielectric edge, thereby affecting the radiation pattern of the phased array antenna unit 100. For this reason, a decoupling structure 200 arranged in a zigzag shape is connected between adjacent phased array antenna units 100. By adding a decoupling structure 200 with a folded line between the phased array antenna units 100, an anti-phase current is introduced to offset the coupling energy between adjacent units, thereby reducing the port coupling degree and improving the stability of the radiation pattern of each unit of the phased array antenna. The decoupling structure 200 is a zigzag line, and its shape can be bent once or more than once, and the bending shape can be a right angle or a circular arc, etc. The two ends of the decoupling structure 200 are respectively connected to the first metal layer 110 of the adjacent phased array antenna units 100.

[0068] Due to the decoupling structure 200 incorporated into the phased array antenna, the spacing between adjacent phased array antenna elements 100 is 0.4λ0 to 0.47λ0, where λ0 is the free-space wavelength. Compared to antenna elements in related technologies, this solution enables a smaller spacing between antenna elements, further improving the design requirements for structural compactness.

[0069] Please refer to Figures 8 to 11 , Figure 8 for Figure 2 The S11 parameter curve corresponding to the phased array antenna unit is as follows: Figure 8 It can be seen that the impedance matching of the phased array antenna unit is better than -10dB in the frequency band of 8.42-8.51GHz. Figure 9 for Figure 1 The curve of reflection coefficient and frequency in the S parameter corresponding to the phased array antenna; Figure 10 for Figure 1 The curve of coupling coefficient and frequency in the S parameter corresponding to the phased array antenna. Figure 9 It can be seen from the figure that the -10dB impedance matching overlap bandwidth is in the 8.42-8.5GHz frequency band; Figure 10 It can be seen that the isolation between ports is better than 21.8dB. In addition, since the phased array antenna of this solution is a symmetrical structure, in order to make the drawing simple and beautiful, only the S parameters between the four phased array antenna units on the same side are provided here. In addition, Figure 9 and Figure 10 In the S-curve, w / o NL means that the decoupling structure is not used, and with NL means that the decoupling structure is used, that is, the coupling parameters before and after the decoupling structure. Obviously, the decoupling effect of using the folded structure is better. Figure 11 is the scanning pattern of the phased array antenna of the present invention, from Figure 11 It can be seen that the scanning range of the phased array antenna of this scheme covers ±86°, the maximum gain is 10.96dB, and the gain is 8.12dB at the maximum scanning angle, which is 2.84dB lower than the maximum gain, and the radiation pattern stability is good.

[0070] In summary, this proposal presents a folded cavity-backed phased array antenna. By folding the traditional resonant cavity and stacking it into a double-layer structure, the overall size of the phased array antenna unit is reduced. Furthermore, by leveraging the high dielectric constant of low-temperature co-fired ceramic (LTCC) technology and the surface wave modulation mechanism between different dielectrics, the half-power beamwidth of the antenna unit is broadened. Based on this unit structure, a curved decoupling structure is employed to form a compact phased array antenna with wide-angle scanning capabilities.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention description and drawings under the technical solution of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A phased array antenna with a folded cavity-backed structure, characterized in that: The phased array antenna of the folded cavity-backed structure comprises at least two electrically connected phased array antenna units, wherein the phased array antenna unit comprises a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, and a differential feed network layer stacked in sequence; A first resonant cavity and a second resonant cavity are formed between the first metal layer and the second metal layer, and a third resonant cavity is formed between the second metal layer and the third metal layer. The first resonant cavity and the second resonant cavity are respectively stacked on the third resonant cavity, and the first resonant cavity and the second resonant cavity are respectively communicated with the third resonant cavity. A first radiation slot corresponding to the first resonant cavity is formed on one side edge of the first metal layer, and the first radiation slot is connected to the first resonant cavity; a second radiation slot corresponding to the second resonant cavity is formed on the other side edge of the first metal layer, and the second radiation slot is connected to the second resonant cavity; The differential feeding network layer is electrically connected to the second metal layer, and the differential feeding network layer is used to feed radio frequency energy into the resonant cavity composed of the first resonant cavity, the second resonant cavity and the third resonant cavity, and output the radio frequency energy received by the resonant cavity composed of the first resonant cavity, the second resonant cavity and the third resonant cavity.

2. The phased array antenna with a folded cavity-backed structure according to claim 1, wherein: The periphery of the first metal layer has a plurality of first metal vias arranged at intervals, the first metal vias sequentially passing through the first metal layer, the first dielectric layer, the second dielectric layer and the third metal layer, and the third resonant cavity is formed in the enclosed space of the second metal layer, the third metal layer and the first metal vias; The second metal layer has a plurality of second metal vias and a third metal via connected to the first metal layer on opposite side edges, the second metal vias sequentially passing through one side of the first dielectric layer and the second metal layer, and the first resonant cavity is formed in the enclosed space of the first metal layer, the second metal layer, the first metal vias, and the second metal vias; The third metal via sequentially penetrates the first dielectric layer and the other side of the second metal layer, and the second resonant cavity is formed in the enclosed space of the first metal layer, the second metal layer, the first metal via and the third metal via.

3. The phased array antenna with a folded cavity-backed structure according to claim 2, wherein: The diameters of the first metal via, the second metal via and the third metal via are all 0.002λ0~0.007λ0, and the hole center spacings between adjacent first metal vias, second metal vias and third metal vias are all 2.5-3 times the metal via diameters, where λ0 is the free space wavelength.

4. The phased array antenna with a folded cavity-backed structure according to claim 1, wherein: The first radiation slot and the second radiation slot are symmetrically distributed and are both long strip openings extending along the width direction of the first metal layer. The lengths of the first radiation slot and the second radiation slot are both 0.16λ0~0.18λ0, and the widths are both 0.006λ0~0.02λ0; the spacing between the first radiation slot and the second radiation slot is 0.17λ0~0.2λ0, where λ0 is the free space wavelength.

5. The phased array antenna with a folded cavity-backed structure according to claim 1, wherein: The length and width of the first metal layer are both 0.23λ0-0.26λ0, the length and width of the second metal layer are both 0.18λ0-0.21λ0, and two ends of the first metal layer extend out from two ends of the second metal layer respectively; the length of the third metal layer is 0.23λ0-0.34λ0, and the width is 0.23λ0-0.26λ0, and two ends of the third metal layer extend out from two ends of the second metal layer respectively; The thickness of the first dielectric layer and the second dielectric layer is 0.03λ0-0.05λ0, and the length and width of the first dielectric layer and the second dielectric layer are both 0.28λ0-0.34λ0, where λ0 is the free space wavelength.

6. The phased array antenna with a folded cavity-backed structure according to claim 1, wherein: It also includes a third dielectric layer located between the third metal layer and the differential feed network layer, the differential feed network layer is arranged on the third dielectric layer, the thickness of the third dielectric layer is 0.01λ0~0.02λ0, and the length and width of the third dielectric layer are both 0.28λ0~0.34λ0, where λ0 is the free space wavelength.

7. The phased array antenna with a folded cavity-backed structure according to claim 6, wherein: The differential feed network layer includes a welding pad, a feed network and a feed coaxial probe, the welding pad is electrically connected to the feed network, the feed network is electrically connected to the feed coaxial probe, the feed coaxial probe sequentially passes through the third dielectric layer, the third metal layer, the second dielectric layer and the second metal layer, and the feed coaxial probe is electrically connected to the second metal layer.

8. The phased array antenna with a folded cavity-backed structure according to claim 7, wherein: The feeding network includes a first power splitting line electrically connected to the welding pad, and a second power splitting line electrically connected to the first power splitting line, wherein the first power splitting line has a characteristic impedance of 50Ω and a width of 0.68mm-0.78mm; the second power splitting line is arranged in a bent manner, has a characteristic impedance of 100Ω, and a width of 0.1mm-0.14mm; The second power dividing line has a first parallel branch and a second parallel branch. The width of the first parallel branch and the second parallel branch are both 0.1 mm-0.14 mm, and the length of the first parallel branch and the second parallel branch are both 2.02 mm-2.52 mm.

9. The phased array antenna with a folded cavity-backed structure according to claim 1, wherein: A decoupling structure arranged in a bent shape is connected between adjacent phased array antenna units.

10. The phased array antenna with a folded cavity-backed structure according to claim 9, wherein: The spacing between adjacent phased array antenna units is 0.4λ0~0.47λ0, where λ0 is the free space wavelength.

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