A planar spiral orbital angular momentum Vivaldi array antenna and method

Abstract

The present invention relates to the field of antennas, and in particular to a planar spiral orbital angular momentum Vivaldi array antenna and method. The antenna comprises four dielectric plates, on each of which two Vivaldi antenna elements are symmetrically printed using a printed circuit board process, for a total of eight elements; the four dielectric plates each comprise an axis of symmetry, and the four dielectric plates are longitudinally spliced ​​along the axis of symmetry to form a basic unit comprising eight sub-blocks of Vivaldi antenna elements, each element being composed of a gradient slot line and a feed balun, which are respectively located on the front and back sides of the dielectric plate; each Vivaldi antenna element has a feed port. The defect that the radiation pattern of a traditional orbital angular momentum antenna is hollow and divergent is overcome, which greatly facilitates the practical application of orbital angular momentum. At the same time, the antenna has a compact structure, a wide impedance bandwidth and a high gain.

Description

Technical Field

[0001] The present invention relates to the field of antennas, and in particular to a planar spiral orbital angular momentum Vivaldi array antenna and a method. Background Art

[0002] In recent years, the unique physical properties of orbital angular momentum technology, which provide a new multiplexing dimension and improve spectrum efficiency, and its promising application prospects have attracted widespread attention from the academic community, making the research of orbital angular momentum antennas a current hot topic. However, due to the central phase singularity of electromagnetic waves carrying orbital angular momentum, the directional patterns of traditional orbital angular momentum antennas are all hollow and divergent, and the radiation energy is difficult to concentrate; this brings many challenges to the reception and demodulation of orbital angular momentum carriers and the architectural design of wireless orbital angular momentum systems.

[0003] In 2016, Professor Zheng Shilie and others from Zhejiang University proposed the concept of planar spiral orbital angular momentum. Studies have shown that the radiation pattern of an antenna radiating planar spiral orbital angular momentum electromagnetic waves is similar to the omnidirectional side-radiation form of a half-wave dipole antenna, rather than the hollow inverted cone of a traditional orbital angular momentum antenna. At the same time, the physical properties of electromagnetic waves carrying planar spiral orbital angular momentum, such as the vortex-shaped phase wavefront and the orthogonality between different modes, are unchanged compared to traditional orbital angular momentum electromagnetic waves. Therefore, the reception and demodulation of a wireless orbital angular momentum system based on a planar spiral orbital angular momentum antenna will be easier to implement, and the system architecture will be greatly simplified. In summary, the planar spiral orbital angular momentum antenna has considerable research value and broad application prospects.

[0004] The research and design of planar spiral orbital angular momentum antennas have not received widespread attention. Existing planar spiral orbital angular momentum antennas only have two forms: metal resonant cavities loaded with horn edges and WGM mode dielectric resonators. However, the antenna form is single, the function is simple, and the design freedom is limited. The present invention proposes an orbital angular momentum antenna based on UCA that completely utilizes rotating gradient phase feeding to generate orbital angular momentum. There is no requirement for the array element antenna itself. The antenna array element can be flexibly selected or optimized according to needs. The design idea is clear and the design freedom is large; the whispering gallery type corresponds to the term WGM. Summary of the invention

[0005] Purpose of the invention: To provide a new hernia belt with better effect. The specific purpose can be seen in the multiple substantial technical effects in the specific implementation part.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A planar spiral orbital angular momentum Vivaldi array antenna, characterized in that the antenna comprises four dielectric plates, two Vivaldi antenna array elements are symmetrically printed on each dielectric plate using a printed circuit board process, and a total of eight array elements; the four dielectric plates each comprise a symmetry axis, and the four dielectric plates are longitudinally spliced ​​along the symmetry axis to form a basic unit comprising eight sub-block Vivaldi antenna array elements, each array element comprises a gradient slot line 5 and a feed balun 6, and the gradient slot line 5 and the feed balun 6 are respectively located on the front and back sides of the dielectric plate; and each Vivaldi antenna array element has a feed port.

[0008] A further technical solution of the present invention is that the four dielectric plates are longitudinally spliced ​​along the symmetry axis to form a compact eight-element ring antenna array.

[0009] A method for widening impedance bandwidth and improving gain for a Vivaldi array antenna, characterized in that, using any of the above-described antennas, the method comprises the following steps: the antenna comprises four dielectric plates, two Vivaldi antenna array elements are symmetrically printed on each dielectric plate using a printed circuit board process, and a total of eight array elements; the electrical size a0 of the array radius does not exceed xl / 2π, and xl is the first extreme point of the l-th order Bessel function; the four dielectric plates are longitudinally spliced ​​along the symmetry axis to form a compact 8-element ring antenna array; 45 o l(n-1)(n=1,2,…,8) rotating gradient phase feeding can generate a plane spiral orbital angular momentum with a mode number of l;

[0010] A further technical solution of the present invention is to use the center of the UCA as the origin and phase reference point; the radius of the circular array is , is the azimuth angle of each array element, all array elements are fed with equal amplitude, and the feeding phase of each array element is (n=1,2,…N); let the solid angle formed by the observation point P(r,θ , φ) in the far field, the origin and the nth array element be ; Therefore, the path difference between the nth array element antenna and the phase reference point to point P is ; So the field pattern factor It can be calculated as

[0011] (1)

[0012] where k is the wave number in free space. When the number of array elements N is large enough and the azimuth interval Δφ=2π / N between adjacent array elements is small enough, equation (1) can be approximated as

[0013] (2)

[0014] in , is the working wavelength in vacuum; it can be seen from formula (2) that by properly setting the array radius a, the array factor pattern can be transformed from a hollow inverted cone to an omnidirectional edge-emitting shape, that is, the transformation from generating traditional orbital angular momentum to generating planar spiral orbital angular momentum can be achieved; the specific analysis is as follows:

[0015] set up is the first extreme point of the l-th order Bessel function, that is, ; From formula (2), we can get: exist To obtain the maximum value, we must have , and the array radius at this time is ;when hour, Will be in The first extreme point is obtained when , that is, the directional pattern of the array is a hollow inverted cone of the traditional orbital angular momentum antenna; when When it is very large, The first extreme point of is close to 0; that is, as the radius of the antenna array increases, its convergence effect on the radiated orbital angular momentum bifurcation beam will become more and more obvious; when , Will still be The extreme value is obtained at At The value obtained at the place; In summary, the circular array antenna using the rotating gradient phase feed, when the array radius electrical size When , it can radiate plane spiral orbital angular momentum electromagnetic waves.

[0016] A further technical solution of the present invention is that at 5 GHz, the eight feeding ports are respectively 0 o , 135 o , 270 o , 45 o , 180 o ,315 o , 90 o , 225 o When fed with a rotating gradient phase, the antenna produces a vortex phase of l=3; the three-dimensional radiation pattern of the antenna array at 5GHz is in the form of omnidirectional broadside radiation, rather than the hollow inverted cone of the traditional orbital angular momentum antenna.

[0017] The present invention adopting the above technical solution has the following beneficial effects compared with the prior art: the planar spiral orbital angular momentum array antenna proposed by the invention can generate a planar spiral orbital angular momentum different from the traditional orbital angular momentum, overcomes the defect that the radiation pattern of the traditional orbital angular momentum antenna is hollow and divergent, and greatly facilitates the practical application of orbital angular momentum. At the same time, the antenna has a compact structure, a wide impedance bandwidth and a high gain. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to further illustrate the present invention, the following is further described in conjunction with the accompanying drawings:

[0019] Figure 1 It is the coordinate system for calculating the far-field array factor field pattern of the ring antenna array.

[0020] Figure 2 It is a schematic structural diagram of an embodiment of the present invention.

[0021] Figure 3 2 is a dimensional parameter diagram of an embodiment of the present invention.

[0022] Figure 4 is the vortex phase diagram generated by the antenna at 5 GHz.

[0023] Figure 5 It is the omnidirectional three-dimensional radiation pattern produced by the antenna at 5GHz.

[0024] Figure 6 It is a schematic diagram of the structure of the slots on the dielectric plate;

[0025] Figure 7 This is a schematic diagram of the structure of the slit under the dielectric plate;

[0026] Figure 8 It is a schematic diagram of the shape of the gradient groove line;

[0027] Among them: 1. Dielectric plate 1; 2. Dielectric plate 2; 3. Dielectric plate 3; 4. Dielectric plate 4; 5. Gradient slot line; 6. Feed balun; 7. Feed port; 8. Upper slot; 9. Lower slot. UCA (Uniform Circular Array) DETAILED DESCRIPTION

[0028] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "top", "bottom", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0029] This patent provides a variety of parallel solutions, and the different expressions are improved solutions or parallel solutions based on the basic solution. Each solution has its own unique characteristics.

[0030] The present invention relates to the field of microwave antennas, and in particular to a Vivaldi planar spiral orbital angular momentum array antenna. The antenna comprises four dielectric plates, on each of which two Vivaldi antenna array elements are symmetrically printed using a printed circuit board process, for a total of eight array elements. According to theoretical analysis, in order for the annular array antenna to generate a planar spiral orbital angular momentum rather than a traditional orbital angular momentum, the electrical dimension a0 of the array radius should not exceed xl / 2π, where xl is the first extreme point of the lth-order Bessel function. Therefore, four dielectric plates are longitudinally spliced ​​along the symmetry axis to form a compact 8-element annular antenna array. 45 o By feeding a rotating gradient phase of l(n-1)(n=1,2,…,8), it can generate a planar spiral orbital angular momentum with a mode number of l. Example

[0031] Current research has shown that the circular array antenna using rotating gradient phase feeding can generate traditional orbital angular momentum electromagnetic waves. Figure 1 As shown, the center of the UCA is the origin and phase reference point. The radius of the circular array is , is the azimuth angle of each array element, all array elements are fed with equal amplitude, and the feeding phase of each array element is (n=1,2,…N). Suppose the observation point P(r, , ), the solid angle formed by the origin and the nth array element is Therefore, the path difference between the nth array element antenna and the phase reference point to point P is . Therefore, the field pattern factor It can be calculated as

[0032] (1)

[0033] where k is the wave number in free space. When the number of array elements N is large enough and the azimuth interval Δφ=2π / N between adjacent array elements is small enough, equation (1) can be approximated as

[0034] (2)

[0035] in , is the working wavelength in vacuum. It can be seen from formula (2) that by properly setting the array radius a, the array factor pattern can be transformed from a hollow inverted cone to an omnidirectional edge-emitting shape, that is, the transformation from generating traditional orbital angular momentum to generating planar spiral orbital angular momentum can be achieved. The specific analysis is as follows:

[0036] set up is the first extreme point of the l-th order Bessel function, that is, From formula (2), we can get: exist To obtain the maximum value, we must have , and the array radius at this time is .when hour, Will be in The first extreme point is obtained when , that is, the directional pattern of the array is a hollow inverted cone of the traditional orbital angular momentum antenna; when When it is very large, The first extreme point of is close to 0; that is, as the radius of the antenna array increases, its convergence effect on the radiated orbital angular momentum bifurcation beam will become more and more obvious. , Will still be The extreme value is obtained at At In summary, for a circular array antenna using a rotating gradient phase feed, when the array radius is When , it can radiate plane spiral orbital angular momentum electromagnetic waves.

[0037] Figure 2A schematic diagram of the structure of a Vivaldi planar spiral orbital angular momentum array antenna provided in an embodiment of the present invention. As shown in the figure, this embodiment is composed of dielectric plates 1, 2, 3, and 4 longitudinally inserted along the symmetry axis of the dielectric plates, and two Vivaldi antenna array elements are printed on each dielectric plate in a mirror-symmetrical manner. Each array element is composed of a gradient slot line 5 and a feed balun 6, and the gradient slot line 5 and the feed balun 6 are respectively located on the front and back sides of the dielectric plate. Each Vivaldi antenna array element has a feed port (such as the feed port 7 shown in the figure; only 3 of the 8 feed ports are marked in the figure), and the feed phase difference between adjacent ports is 135 o .

[0038] In this specific embodiment, in order to generate a plane spiral orbital angular momentum electromagnetic wave with a mode number l=3 at 5 GHz, after optimization design, it is finally determined Figure 3 The parameter dimensions are as follows: (Unit: mm)

[0039] parameter W L W LS Rc Lb Value(mm) 54.4 81.6 27.2 40.8 3.1 17

[0040] The commercial finite element simulation software ANSYS HFSS was used to perform simulation analysis on this embodiment. Figure 4 As shown, at 5 GHz, the eight feeding ports are respectively o , 135 o , 270 o , 45 o , 180 o ,315 o , 90 o , 225 o When fed with a rotating gradient phase, the antenna produces a vortex phase of l=3; Figure 5 As shown in the figure, the three-dimensional radiation pattern of the antenna array at 5GHz is in the form of omnidirectional side-beam, rather than the hollow inverted cone of the traditional orbital angular momentum antenna. At the same time, the gain peak of the antenna array at 5GHz is about 6dB, and the relative impedance bandwidth is about 85% (4GHz to 10GHz, VSWR<2), which has outstanding practical value.

[0041] Innovatively, each of the above effects exists independently, and a set of structures can be used to combine the above results.

[0042] Regarding the production of this patent: (1) There is a gap in the middle of the dielectric plate. There are four dielectric plates in total, which are welded together by longitudinal splicing. When we use Ansoft HFSS to simulate, the simulation results are the same when there is no gap in the middle and when there is a gap, but there is a gap in the actual design. Figure 6 and Figure 7 As shown;

[0043] There are two ways to make the slits: top slits and bottom slits. Among the four media boards, take one and make it the top slit, and the other three and make it the bottom slits, and then splice them longitudinally to make them into a whole. Figure 2 shown.

[0044] This paper studies the Vivaldi antenna with four dielectric plates and eight antenna elements.

[0045] (3) The phase-shift power division feeding network is shown in the figure:

[0046] The feeding line of the antenna is a coaxial line, which is fed through the SMA interface welded on the exposed lumped port of the feeding bottom plate.

[0047] (4) The structure of the gradient slot line and the feeding balun is as follows:

[0048] The gradient slot line and the balun transition section are located on the front and back sides of the dielectric plate respectively, and are both metal patches. The balun transition section uses a coupled feeding method to ensure balanced feeding of the slot line. The balun transition section is directly connected to the feeding network.

[0049] The technical effect achieved by the above structure is clear. If no additional technical solutions are considered, the patent name can also be a new type of antenna. Some details are not shown in the figure.

[0050] It should be noted that the multiple solutions provided by this patent include the basic solution itself, which are independent of each other and do not restrict each other, but they can also be combined with each other without conflict to achieve multiple effects together.

[0051] The basic principle, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the protection required.

Claims

1. A planar spiral orbital angular momentum Vivaldi array antenna, characterized in that: The antenna comprises four dielectric plates, on each of which two Vivaldi antenna array elements are symmetrically printed using a printed circuit board process, with a total of eight array elements; the four dielectric plates each comprise a symmetry axis, and the four dielectric plates are longitudinally spliced ​​along the symmetry axis to form a basic unit comprising eight sub-block Vivaldi antenna array elements, each array element being composed of a gradient slot line (5) and a feeding balun (6), and the gradient slot line (5) and the feeding balun (6) are respectively located on the front and back sides of the dielectric plate; each Vivaldi antenna array element has a feeding port; The four dielectric plates are longitudinally spliced ​​along the axis of symmetry to form a compact eight-element ring antenna array; among the four dielectric plates, one is taken out to be made into a top slit, and the other three are made into bottom slits, and then they are made into a whole by longitudinal splicing.

2. A method for widening impedance bandwidth and improving gain for Vivaldi array antenna, characterized in that: The antenna described in claim 1 includes the following steps: the antenna includes 4 dielectric plates, each of which has 2 Vivaldi antenna array elements symmetrically printed using a printed circuit board process, for a total of 8 array elements; the electrical size a0 of the array radius does not exceed xl / 2π, where xl is the first extreme point of the lth-order Bessel function; the 4 dielectric plates are longitudinally spliced ​​along the symmetry axis to form a compact 8-element ring antenna array; the 8 array elements are fed with a 45°l(n-1) (n=1, 2, ..., 8) rotational gradient phase in sequence to generate a planar spiral orbital angular momentum with a mode number of l.

3. A method for widening impedance bandwidth and improving gain for a Vivaldi array antenna as claimed in claim 2, characterized in that: The center of the UCA is the origin and phase reference point; the radius of the circular array is a, φ n is the azimuth angle of each array element, all array elements are fed with equal amplitude, and the feeding phase of each array element is Φ n = lφ n (n=1,2,…N); let the solid angle formed by the observation point P(r,θ,φ) in the far field, the origin and the nth array element be α n ; Therefore, the path difference between the nth array element antenna and the phase reference point to point P is acos α n ; Therefore, the field pattern factor F(θ, φ) can be calculated as where k is the wave number in free space. When the number of array elements N is large enough and the azimuth interval Δφ = 2π / N between adjacent array elements is small enough, equation (1) can be approximated as The array radius a λ =a / λ, λ is the working wavelength in vacuum; It can be seen from formula (2) that by properly setting the array radius a, the array factor pattern can be transformed from a hollow inverted cone to an omnidirectional edge-emitting shape, that is, the transformation from generating traditional orbital angular momentum to generating planar spiral orbital angular momentum can be realized; The specific analysis is as follows: Let x1 be the first extreme point of the I-order Bessel function, that is, J l (x l )=0; From formula (2), we can get that if F(θ, φ) reaches its maximum value at θ=90°, then 2πa λ =x l , and the array radius at this time is a λ0 =x l / 2π; when a λ >a λ0 When J l (2πa λ sinθ) will reach the first extreme point when 0°<θ<90°, that is, the array's directional pattern is a hollow inverted cone of a traditional orbital angular momentum antenna; when a λ When it is very large, J l (2πa λ sinθ) will be obtained when θ is close to 0; that is, as the radius of the antenna array increases, its convergence effect on the radiated orbital angular momentum bifurcation beam will become more and more obvious; when a λ λ0 , J l (2πa λ sinθ) will still reach its extreme value at θ = 90°, but this extreme value will be smaller than a λ =a λ0 The value obtained at θ = 90°; In summary, the circular array antenna using the rotating gradient phase feed has an array radius electrical size a λ =x l / 2π, it can radiate plane spiral orbital angular momentum electromagnetic waves.​ 4. A method for widening impedance bandwidth and improving gain for a Vivaldi array antenna as claimed in claim 2, characterized in that: At 5 GHz, when the eight feeding ports were fed with rotational gradient phases of 0°, 135°, 270°, 45°, 180°, 315°, 90°, and 225° respectively, the antenna produced a vortex phase of I=3; the three-dimensional radiation pattern of the antenna array at 5 GHz was in the form of omnidirectional side-beams, rather than the hollow inverted cone of the traditional orbital angular momentum antenna.

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