Phased array antenna with folding back cavity structure

Abstract

The invention discloses a phased-array antenna with a folded back cavity structure, which comprises at least two electrically connected phased-array antenna units, and is characterized in that each 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 which are stacked in sequence; a first resonant cavity and a second resonant cavity which are opposite to each other are formed between the first metal layer and the second metal layer, 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; the edges of the two sides of the first metal layer are respectively provided with two radiation slots, and the two radiation slots are respectively communicated with the two corresponding resonant cavities; and the differential feed network layer is electrically connected with the second metal layer. According to the invention, through folding the resonant cavity, the structure space can be saved, the design requirements of compact structure and miniaturization are met, and wide-angle scanning can be realized at the same time.

Description

Technical Field

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

[0002] Phased array antennas have the ability of fast beam scanning, which get rid of the disadvantages of slow speed and low accuracy of traditional mechanical beam scanning arrays. Therefore, they have been attracting much attention in the academic and commercial fields. With the rapid development and popularization of 5G technology and wireless technology, the performance of phased array antennas such as scanning coverage, structural compactness and stability has become the key indicators to measure the quality of phased array antennas.

[0003] In order to improve the scanning coverage of phased array antennas, most of the existing solutions use wide beam antenna elements or pattern reconfigurable elements 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", in which high impedance surfaces were used to conduct surface waves to achieve the effect of broadening the beam width. In the above solution, a 1×8 wide-angle scanning phased array unit was finally composed based on the high impedance surface, and the scanning angle range covered from -85° to 85°. The gain in the maximum gain direction reached 13.8 dBi, and the gain in the maximum scanning angle direction reached 10.9 dBi. The decrease compared with the maximum gain was less than 3 dBi, and the sidelobe level was always less than the maximum gain -10 dB throughout the scanning range. However, in the above solution, due to the need to use high impedance surfaces, the overall height of the phased array antenna increases, which does not meet the design requirements of structural compactness 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] To solve the above-mentioned at least one technical problem, the main object of the present invention is to provide a phased array antenna with a folded back cavity structure.

[0006] To achieve the above object, a technical solution adopted by the present invention is: to provide a phased array antenna with a folded back cavity structure, including at least two electrically connected phased array antenna units, and the phased array antenna unit includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, and a differential feeding network layer that are sequentially stacked. A first resonant cavity and a second resonant cavity are formed opposite to each other between the first metal layer and the second metal layer. 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; One side edge of the first metal layer has a first radiation slot corresponding to the first resonant cavity, and the first radiation slot is communicated with the first resonant cavity; the other side edge of the first metal layer has a second radiation slot corresponding to the second resonant cavity, and the second radiation slot is communicated with the second resonant cavity; The differential feed network layer is electrically connected to the second metal layer. The differential feed 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.

[0007] Wherein, the periphery of the first metal layer has a plurality of first metal vias arranged at intervals. The first metal vias sequentially penetrate through the first metal layer, the first dielectric layer, the second dielectric layer and the third metal layer. 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 two opposite side edges of the second metal layer respectively have a plurality of second metal vias and third metal vias connected to the first metal layer. The second metal vias sequentially penetrate through the first dielectric layer and one side of the second metal layer. 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 vias sequentially penetrate through the first dielectric layer and the other side of the second metal layer. The second resonant cavity is formed in the enclosed space of the first metal layer, the second metal layer, the first metal vias and the third metal vias.

[0008] Wherein, the diameters of the first metal vias, the second metal vias and the third metal vias are all 0.002λ0 to 0.007λ0, and the center-to-center distances between adjacent first metal vias, second metal vias and third metal vias are all 2.5 - 3 times the diameter of the metal vias. Wherein, λ0 is the free space wavelength.

[0009] Wherein, the first radiation slot and the second radiation slot are symmetrically distributed and are both strip-shaped 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 to 0.18λ0, and the widths are both 0.006λ0 to 0.02λ0; the distance between the first radiation slot and the second radiation slot is 0.17λ0 to 0.2λ0. Wherein, λ0 is the free space wavelength.

[0010] Among them, the length and width of the first metal layer are both 0.23λ0 to 0.26λ0, the length and width of the second metal layer are both 0.18λ0 to 0.21λ0, and both ends of the first metal layer extend beyond both ends of the second metal layer. The length of the third metal layer is 0.23λ0 to 0.34λ0, and the width is 0.23λ0 to 0.26λ0, and both ends of the third metal layer extend beyond both ends of the second metal layer; The thickness of the first dielectric layer and the second dielectric layer is 0.03λ0 to 0.05λ0, and the length and width of the first dielectric layer and the second dielectric layer are both 0.28λ0 to 0.34λ0, where λ0 is the free space wavelength.

[0011] Among them, it further includes a third dielectric layer located between the third metal layer and the differential feeding network layer. The differential feeding network layer is disposed on the third dielectric layer. The thickness of the third dielectric layer is 0.01λ0 to 0.02λ0, and the length and width of the third dielectric layer are both 0.28λ0 to 0.34λ0, where λ0 is the free space wavelength.

[0012] Among them, the differential feeding network layer includes a bonding pad, a feeding network, and a feeding coaxial probe. The bonding pad is electrically connected to the feeding network, the feeding network is electrically connected to the feeding coaxial probe, and the feeding coaxial probe sequentially penetrates through the third dielectric layer, the third metal layer, the second dielectric layer, and the second metal layer, and the feeding coaxial probe is electrically connected to the second metal layer.

[0013] Among them, the feeding network includes a first power divider electrically connected to the bonding pad and a second power divider electrically connected to the first power divider. The first power divider has a characteristic impedance of 50Ω and a width of 0.68 mm - 0.78 mm; the second power divider is bent and has a characteristic impedance of 100Ω and a width of 0.1 mm - 0.14 mm; The second power divider has a first parallel stub and a second parallel stub. The widths of the first parallel stub and the second parallel stub are both 0.1 mm - 0.14 mm, and the lengths are both 2.02 mm - 2.52 mm.

[0014] Among them, a decoupling structure arranged in a bent shape is connected between adjacent phased array antenna units.

[0015] Among them, the spacing between adjacent phased array antenna units is 0.4λ0 to 0.47λ0, where λ0 is the free space wavelength.

[0016] The technical solution of the present invention includes a plurality of adjacent phased array antenna units. Each phased array antenna unit includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, and a differential feeding network layer. Among them, 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 stacked on the third resonant cavity and are each communicated with the third resonant cavity to obtain a folded resonant cavity structure, which can save structural space and meet the design requirements of structural compactness and miniaturization. The first metal layer has a first radiation slot and a second radiation slot. The differential feeding network layer is electrically connected to the second metal layer. During radio frequency transmission, the radio frequency energy to be transmitted is fed into the folded resonant cavity through the differential feeding network layer, and an electromagnetic resonance is formed in the resonant cavity, and then radiated out through the first radiation slot and the second radiation slot of the first metal layer to form an electromagnetic wave propagating in free space. During radio frequency reception, the electromagnetic wave in free space enters the folded resonant cavity through the first radiation slot and the second radiation slot, and an electromagnetic resonance is formed in the folded resonant cavity, and then is output to an external port through the differential feeding network layer electrically connected to the second metal layer. In addition, this solution has a plurality of phased array antenna units. By selecting feeding with different excitation phases at different ports, the scanning angle of the phased array antenna can be changed to achieve wide-angle scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without creative efforts.

[0018] Figure 1 It is a schematic exploded view of a phased array antenna with a folded back cavity structure according to an embodiment of the present invention; Figure 2 It is a schematic exploded view of a phased array antenna unit according to an embodiment of the present invention; Figure 3 It is a schematic structural view of a folded resonant cavity according to an embodiment of the present invention; Figure 4 It is a top view of a first metal layer according to an embodiment of the present invention; Figure 5 It is a top view of a second metal layer according to an embodiment of the present invention; Figure 6 It is a top view of a third metal layer according to an embodiment of the present invention; Figure 7 It is a top view of a differential feeding network layer according to an embodiment of the present invention; Figure 8 For Figure 2 The S11 parameter curve corresponding to the phased array antenna element in Figure 9 For Figure 1 The curve of the reflection coefficient vs. frequency in the S parameters corresponding to the phased array antenna in Figure 10 For Figure 1 The curve of the coupling coefficient vs. frequency in the S parameters corresponding to the phased array antenna in Figure 11 This is the scanning pattern of the phased array antenna of the present invention.

[0019] Label description: 100, Phased array antenna element: 110, First metal layer, 111, First radiation slot, 112, Second radiation slot, 113, First metal via; 120, Second metal layer, 121, Second metal via, 122, Third metal via, 123, Feeding connection hole; 130, Third metal layer, 131, Feeding avoidance hole; 140, Differential feeding network layer, 141, Solder pad, 142, Feeding network, 143, Feeding coaxial probe, 1421, First power divider line, 1422, Second power divider line, 1423, First shunt stub, 1424, Second shunt stub; 151, First dielectric layer, 152, Second dielectric layer, 153, Third dielectric layer, 161, First resonant cavity, 162, Second resonant cavity, 163, Third resonant cavity; 200, Decoupling structure.

[0020] The realization, functional features and advantages of the objectives of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] It should be noted that the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. Additionally, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] Different from the phased array antenna in the related art, when realizing wide-angle scanning, a high-impedance surface needs to be used, resulting in an increase in the overall height of the phased array antenna, which does not meet the design requirements of structural compactness and miniaturization. The present invention provides a phased array antenna with a folded back cavity structure. By folding the resonant cavity, it can save structural space, meet the design requirements of compactness and miniaturization, and at the same time can change the scanning angle of the phased array antenna to achieve wide-angle scanning. The specific structure of the phased array antenna with the folded back cavity structure is as follows with reference to the following embodiments.

[0024] Please refer to Figures 1 to 7 , Figure 1 is a schematic exploded view of a phased array antenna with a folded back cavity structure according to an embodiment of the present invention; Figure 2 is a schematic exploded view of a phased array antenna unit according to an embodiment of the present invention; Figure 3 is a schematic structural view of a folded resonant cavity according to an embodiment of the present invention; Figure 4 is a top view of a first metal layer according to an embodiment of the present invention; Figure 5 is a top view of a second metal layer according to an embodiment of the present invention; Figure 6 is a top view of a third metal layer according to an embodiment of the present invention; Figure 7 is a top view of a differential feeding network layer according to an embodiment of the present invention. In the embodiments of the present invention, the phased array antenna with 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. The adjacent phased array antenna units 100 are electrically connected. At the same time, considering that the distance between adjacent phased array antenna units 100 becomes smaller and the coupling between the phased array antenna units 100 also becomes larger, decoupling units 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 different feeding excitation phases at different ports, the scanning angle of the phased array antenna is changed to achieve wide-angle scanning.

[0025] 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 feeding network layer 140 that are sequentially stacked; 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 respectively stacked on the third resonant cavity 163, and the first resonant cavity 161 and the second resonant cavity 162 are respectively communicated with the third resonant cavity 163; One side edge of the first metal layer 110 has a first radiation slot 111 corresponding to the first resonant cavity 161, and the first radiation slot 111 is communicated with the first resonant cavity 161; the other side edge of the first metal layer 110 has a second radiation slot 112 corresponding to the second resonant cavity 162, and the second radiation slot 112 is communicated with the second resonant cavity 162; The differential feeding network layer 140 is electrically connected to the second metal layer 120. The differential feeding network layer 140 is configured 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.

[0026] In this embodiment, the phased array antenna unit 100 is divided 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 feeding network layer 140 from top to bottom. The materials of the first dielectric layer 151 and the second dielectric layer 152 can be Ferro - A6M, air, FR4, etc. Symmetric first resonant cavities 161 and second resonant cavities 162 are formed between the first metal layer 110 and the second metal layer 120, and 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 respectively stacked above the third resonant cavity 163 and are respectively communicated with the third resonant cavity 163. That is, the resonant cavity of this solution is a double - layer resonant cavity. Through the double - layer resonant cavity structure, the folding design of the resonant cavity is realized. The occupied area of the resonant cavity is smaller and the structure is more compact, meeting the design requirements of miniaturization. The size of the double - layer resonant cavity is adjustable, and thus the resonant frequency of the radio frequency energy can be adjusted. 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 respectively. 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 at the four peripheral edges of the second metal layer 120. Through these gaps, the first dielectric layer 151 and the second dielectric layer 152 can be connected to form an integral resonant cavity. The first radiation slot 111 and the second radiation slot 112 are both strip - shaped openings. Through the first radiation slot 111 and the second radiation slot 112, the radio frequency energy in the double - layer resonant cavity can be converted into electromagnetic waves radiated into 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.

[0027] When realizing radio frequency transmission, the radio frequency 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 electromagnetic resonance is formed in the cavity. Then, it is radiated out from the first radiation slot 111 and the first radiation slot 111 on the first metal layer 110 to form electromagnetic waves propagating in free space. When realizing radio frequency reception, the electromagnetic waves in free space enter 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 electromagnetic resonance is formed in the cavity. Then, it is output to an external port through the differential feeding network layer 140 electrically connected to the second metal layer 120.

[0028] In a specific embodiment, the periphery of the first metal layer 110 has a plurality of first metal vias 113 arranged at intervals. The first metal vias 113 sequentially penetrate through 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 of the second metal layer 120, the third metal layer 130, and the first metal vias 113; On opposite side edges of the second metal layer 120, there are respectively a plurality of second metal vias 121 and third metal vias 122 connected to the first metal layer 110. The second metal vias 121 sequentially penetrate through 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; The third metal vias 122 sequentially penetrate through the first dielectric layer 151 and the other side of the second metal layer 120. The second resonant cavity 162 is formed in the enclosed space of the first metal layer 110, the second metal layer 120, the first metal vias 113, and the third metal vias 122. The above-mentioned first metal vias 113 realize the connection between the first metal layer 110 and the third metal layer 130, and the second metal vias 121 and the third metal vias 122 realize the connection between the first metal layer 110 and the second metal layer 120. The plurality of first metal vias 113 are distributed in a rectangular shape. The second metal vias 121 and the third metal vias 122 are symmetrically arranged, and the plurality of second metal vias 121 and the third metal vias 122 are both distributed in rows or columns.

[0029] In a specific embodiment, the diameters of the first metal vias 113, the second metal vias 121, and the third metal vias 122 are all 85um - 254um, corresponding to 0.002λ0~0.007λ0. The center-to-center spacing of adjacent first metal vias 113, second metal vias 121, and third metal vias 122 is 2.5 - 3 times the diameter of the metal vias. The diameters of the above-mentioned 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, the second metal vias 121, and the third metal vias 122 can be flexibly adjusted according to actual requirements.

[0030] In a specific embodiment, the first radiation slot 111 and the second radiation slot 112 are symmetrically distributed and are both strip-shaped openings extending along the width direction of the first metal layer 110. The lengths of the first radiation slot 111 and the second radiation slot 112 are both 5.8 mm to 6.5 mm, corresponding to 0.16λ0 to 0.18λ0, and the widths are both 0.2 mm to 0.8 mm, corresponding to 0.006λ0 to 0.02λ. The distance between the first radiation slot 111 and the second radiation slot 112 is 6 mm to 7.1 mm, corresponding to 0.17λ0 to 0.2λ0. The first radiation slot 111 and the second radiation slot 112 are symmetrically distributed, and the slot sizes can meet the transceiver frequency band requirements of the antenna in the range of 8.42 GHz - 8.51 GHz. It can be understood that different frequency band requirements of the antenna can be met by designing slots with different sizes.

[0031] 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 both ends of the first metal layer 110 extend beyond both ends of the second metal layer 120. 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 both ends of the third metal layer 130 extend beyond both ends of the second metal layer 120. The thickness of the first dielectric layer 151 and the second dielectric layer 152 is 0.96 mm - 1.632 mm, corresponding to 0.03λ0 - 0.05λ0. The length and width of the first dielectric layer 151 and the second dielectric layer 152 are both 10 mm - 12 mm, corresponding to 0.28λ0 - 0.34λ0. In this embodiment, the length and width of the metal layer are approximately half a wavelength. Since the dielectric substrate material used in this solution is a high dielectric constant material (its dielectric constant is 5.9 and the loss tangent is 0.002), the length and width of the first metal layer 110 are adjusted. Since the second metal layer 120 needs to conduct the upper and lower layer resonators, its area size is slightly smaller than that of the first metal layer 110. Since the third metal layer 130 needs to consider the size of the welding pad 141, its length dimension is slightly larger than the length of the first metal layer 110, and the width is the same as that of the first metal layer 110. The thicknesses of the dielectric layer and the metal layer are both limited by the LTCC process. The thickness of the dielectric layer needs to be an integer multiple of 96 um, and at the same time, the maximum number of layers is limited to 40. In the present invention, the thicknesses of the first metal layer 110 to the third metal layer 130 are all 9.73 um - 10.3 um, corresponding to 0.0026λ0 - 0.0029λ0. At the same time, the influence of the dielectric constant of the dielectric substrate material on the dielectric layer and the metal layer is considered. The actual thickness of the dielectric layer and the metal layer is the free space wavelength divided by the arithmetic square root of the dielectric constant. The length and width of the first metal layer 110 and the second metal layer, and the thickness, length, and width of the first dielectric layer 151 and the second dielectric layer can all be flexibly adjusted according to actual needs.

[0032] Taking the dielectric constant of 5.9 as an example: the thicknesses of the first metal layer 110 to the third metal layer 130 are all 0.0026λ0 - 0.0029λ0, and their actual thickness is 0.0011λ d -0.0012λ d , where λ d is the antenna operating wavelength. 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 similarly converted into the antenna operating wavelength. This antenna operating wavelength is related to the dielectric substrate of different materials selected.

[0033] Specifically, it further includes a third dielectric layer 153 located between the third metal layer 130 and the differential feeding network layer 140. The differential feeding network layer 140 is disposed on the third dielectric layer 153. The thickness of the third dielectric layer 153 is 0.384 mm - 0.576 mm, corresponding to 0.01λ0 - 0.02λ0. The length and width of the third dielectric layer 153 are both 10 mm - 12 mm, corresponding to 0.28λ0 - 0.34λ0. Among them, the thickness, length, and width of the third dielectric layer 153 can be flexibly adjusted according to needs.

[0034] In a specific embodiment, the differential feeding network layer 140 includes a welding pad 141, a feeding network 142, and a feeding coaxial probe 143. The welding pad 141 is electrically connected to the feeding network 142, and the feeding network 142 is electrically connected to the feeding coaxial probe 143. The feeding coaxial probe 143 sequentially penetrates through the third dielectric layer 153, the third metal layer 130, the second dielectric layer 152, and the second metal layer 120, and the feeding coaxial probe 143 is electrically connected to the second metal layer 120. The welding pad 141 is connected to the SMPS port. The feeding network 142 is a microstrip line. A feeding avoidance hole 131 is provided on the third metal layer 130, and a feeding connection hole 123 is provided on the second metal layer 120. One end of the feeding coaxial probe 143 is connected to the microstrip line, and the other end passes through the feeding avoidance hole 131 and is connected to the feeding connection hole 123.

[0035] Specifically, the feeding network 142 includes a first power divider line 1421 electrically connected to the welding pad 141, and a second power divider line 1422 electrically connected to the first power divider line 1421. The first power divider line 1421 has a characteristic impedance of 50 Ω and a width of 0.68 mm - 0.78 mm. The second power divider line 1422 is bent and has a characteristic impedance of 100 Ω and a width of 0.1 mm - 0.14 mm. The second power divider 1422 has a first parallel stub 1423 and a second parallel stub 1424. The widths of the first parallel stub 1423 and the second parallel stub 1424 are both 0.1 mm - 0.14 mm, and the lengths are both 2.02 mm - 2.52 mm. In this embodiment, the differential feeding network layer 140 first feeds radio frequency energy through the welding pad 141 to the smps port, and then divides the power into two through the power divider. The characteristic impedances before and after power division correspond to 50Ω and 100Ω respectively. The one with a larger width dimension has a lower characteristic impedance, and the one with a smaller width dimension has a higher characteristic impedance. The widths of the first power divider 1421 and the second power divider 1422 can be flexibly adjusted according to requirements. To achieve differential input, at this time, the lengths of the two power dividers after power division should differ by half a wavelength. It should be noted that this half wavelength is not the half wavelength in free space, and the dielectric constant and thickness of the medium need to be considered. The length difference range in this solution is 9.3 - 10 mm. The folding of the second power divider 1422 is to save space, and there can be different folding methods. That is, the second power divider 1422 can be folded multiple times. In addition, a first parallel stub 1423 is connected to the second power divider 1422. The first parallel stub 1423 is located in and connected to the bent section at one end of the second power divider 1422. The first parallel stub 1423 is parallel to the end section of the second power divider 1422. A second parallel stub 1424 is also connected to the second power divider 1422. The second parallel stub 1424 is perpendicularly connected to the end section of the second power divider 1422 to achieve impedance matching. The widths and lengths of the above-mentioned first parallel stub 1423 and second parallel stub 1424 can be flexibly adjusted according to needs.

[0036] Affected by the material characteristics of the dielectric substrate, some surface waves will propagate along the dielectric surface and radiate at the dielectric edge, thus affecting the radiation pattern of the phased array antenna element 100. Therefore, a decoupling structure 200 arranged in a bent shape is connected between adjacent phased array antenna elements 100. By adding the decoupling structure 200 of the folding line between the phased array antenna elements 100, an anti-phase current is introduced to cancel the coupling energy between adjacent units, thereby reducing the port coupling degree and improving the pattern stability of each unit of the phased array antenna. The decoupling structure 200 is a bent line, and its shape can be bent once or more than once. The bent shape can be a right angle or an arc shape, etc. Both ends of the decoupling structure 200 are respectively connected to the first metal layer 110 of adjacent phased array antenna elements 100.

[0037] Since the decoupling structure 200 is introduced into the phased array antenna, the spacing between adjacent phased array antenna elements 100 is 0.4λ0 - 0.47λ0, where λ0 is the free space wavelength. Compared with the antenna elements in the related art, this solution can achieve a smaller antenna element spacing design, further meeting the design requirements for structural compactness.

[0038] Please refer to Figures 8 to 11 , Figure 8 which is Figure 2 the S11 parameter curve corresponding to the phased array antenna element in Figure 8 . It can be seen from Figure 9 that the impedance matching of the phased array antenna element is better than -10 dB in the frequency band range of 8.42 - 8.51 GHz. Figure 1 is the curve of the reflection coefficient versus frequency in the S parameters corresponding to the phased array antenna in Figure 10 ; Figure 1 is the curve of the coupling coefficient versus frequency in the S parameters corresponding to the phased array antenna in Figure 9 . Among them, it can be seen from Figure 10 that the -10 dB impedance matching overlapping bandwidth is the frequency band of 8.42 - 8.5 GHz; it can be seen from Figure 9 and Figure 10 that the isolation between ports is better than 21.8 dB. In addition, since the phased array antenna in this solution is a symmetric structure, for the sake of simplicity and beauty in drawing, only the S parameters between four phased array antenna elements on the same side are provided here. In addition, Figure 11 is the scanning pattern of the phased array antenna of the present invention. It can be seen from Figure 11 that the scanning range of the phased array antenna of this solution covers ±86°, the maximum gain is 10.96 dB, and the gain at the maximum scanning angle is 8.12 dB, which is 2.84 dB lower than the maximum gain, and the pattern stability is good.

[0039] In summary, for the phased array antenna with a folded back cavity structure in this solution, by folding the traditional resonant cavity and stacking it into a double-layer structure, the overall size of the phased array antenna element is reduced. At the same time, due to the material characteristics of high dielectric constant of the low-temperature co-fired ceramic (LTCC) process, the half-power beam width of the antenna element is broadened by using the surface wave regulation mechanism between different dielectrics. Based on this unit structure, a phased array antenna with a compact structure and large-angle scanning ability is formed by using a bent decoupling structure.

[0040] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical solution concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A phased array antenna with a foldable back cavity structure, characterized in that The phased array antenna with a folded back cavity structure includes at least two electrically connected phased array antenna units, and each phased array antenna unit includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, and a differential feeding network layer which are stacked in sequence. A first resonant cavity and a second resonant cavity are formed between the first metal layer and the second metal layer, 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. One side edge of the first metal layer has a first radiation slot corresponding to the first resonant cavity, and the first radiation slot is communicated with the first resonant cavity; the other side edge of the first metal layer has a second radiation slot corresponding to the second resonant cavity, and the second radiation slot is communicated with 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 for feeding radio frequency energy into the resonant cavity composed of the first resonant cavity, the second resonant cavity and the third resonant cavity, and outputting 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 back cavity structure according to claim 1, wherein The periphery of the first metal layer has a plurality of first metal vias arranged at intervals, and the first metal vias sequentially penetrate 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. Both side edges of the second metal layer respectively have a plurality of second metal vias and third metal vias connected to the first metal layer, the second metal vias sequentially penetrate through the first dielectric layer and one side of 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 vias sequentially penetrate through 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 vias and the third metal vias.

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

4. The phased array antenna with a folded back cavity structure according to claim 1, characterized in that, The first radiation slot and the second radiation slot are symmetrically distributed and are both strip-shaped 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 distance 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 back cavity structure according to claim 1, characterized in that, The length and width of the first metal layer are both 0.23λ0 to 0.26λ0, the length and width of the second metal layer are both 0.18λ0 to 0.21λ0, and the two ends of the first metal layer respectively extend beyond the two ends of the second metal layer. The length of the third metal layer is 0.23λ0 to 0.34λ0, and the width is 0.23λ0 to 0.26λ0, and the two ends of the third metal layer respectively extend beyond the two ends of the second metal layer; The thickness of the first dielectric layer and the second dielectric layer is 0.03λ0 to 0.05λ0, and the length and width of the first dielectric layer and the second dielectric layer are both 0.28λ0 to 0.34λ0, where λ0 is the free space wavelength.

6. The phased array antenna with a folded back cavity structure according to claim 1, characterized in that, It further includes a third dielectric layer located between the third metal layer and the differential feeding network layer. The differential feeding network layer is disposed on the third dielectric layer. The thickness of the third dielectric layer is 0.01λ0 to 0.02λ0, and the length and width of the third dielectric layer are both 0.28λ0 to 0.34λ0, where λ0 is the free space wavelength.

7. The phased array antenna with a folded back cavity structure according to claim 6, characterized in that, The differential feeding network layer includes a bonding pad, a feeding network, and a feeding coaxial probe. The bonding pad is electrically connected to the feeding network, the feeding network is electrically connected to the feeding coaxial probe. The feeding coaxial probe sequentially penetrates through the third dielectric layer, the third metal layer, the second dielectric layer, and the second metal layer, and the feeding coaxial probe is electrically connected to the second metal layer.

8. The phased array antenna with a folded back cavity structure according to claim 7, characterized in that, The feeding network includes a first power divider electrically connected to the bonding pad, and a second power divider electrically connected to the first power divider. The first power divider has a characteristic impedance of 50Ω and a width of 0.68 mm - 0.78 mm; the second power divider is bent and has a characteristic impedance of 100Ω and a width of 0.1 mm - 0.14 mm; The second power divider has a first parallel stub and a second parallel stub. The widths of the first parallel stub and the second parallel stub are both 0.1 mm - 0.14 mm, and the lengths are both 2.02 mm - 2.52 mm.

9. The phased array antenna with a folded back cavity structure according to claim 1, characterized in that, A decoupling structure arranged in a bent shape is connected between adjacent phased array antenna elements.

10. The phased array antenna with a folded back cavity structure according to claim 9, characterized in that, The spacing between adjacent phased array antenna elements is 0.4λ0 to 0.47λ0, where λ0 is the free space wavelength.

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