A broadband folded transmission array antenna generating OAM beams and a design method

Abstract

The application provides a broadband folded transmission array antenna generating an OAM beam and a design method, and relates to the electromagnetic technical field.The array antenna comprises a first super atom array, a second super atom array and an open waveguide feed source;the first super atom array is composed of a plurality of first super atom arrays, and the second super atom array is composed of a plurality of second super atom arrays;the first super atom array is arranged above the second super atom array and the central projections of the two along the vertical direction coincide;the preset second super atom at the center of the second super atom array is removed to place the open waveguide feed source, and the design of the array antenna is completed;phase compensation is provided through the first super atom array, and finally, the OAM beam is generated.The antenna profile of the broadband folded transmission array antenna is further reduced, the bandwidth is significantly improved, the efficiency is higher and more stable.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic technology, specifically microwave radio frequency technology, and particularly relates to a broadband folded transmission array antenna for generating OAM beams and its design method. Background Technology

[0002] Currently, reflective array antennas (RA) and transmit-array antennas (RA), as representatives of high-gain antennas in recent years, have been a focus of researchers. However, due to their use of spatial feed mode, their profile is too high, which does not conform to the miniaturization trend of future communication systems. Folded transmit-array antennas (FTA) and folded reflective array antennas (FRA) have successfully reduced the system profile by using ray tracing principles, but they often focus on high-gain beams while neglecting other interesting functions such as OAM, and they suffer from narrowband and inefficiency.

[0003] Therefore, how to provide a broadband folded transmission array antenna that generates OAM beams and its design method has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a broadband folded transmission array antenna and design method for generating OAM beams, thereby solving the technical problem that current folded transmission antennas (FTAs) lack miniaturized, low-profile, multifunctional multiplexed transmission arrays capable of generating OAM beams.

[0005] According to a first aspect of the present invention, a broadband folded transmission array antenna for generating OAM beams is provided, the array antenna comprising: a first superatomic array, a second superatomic array, and an open waveguide feed;

[0006] The first superatomic array is composed of multiple first superatomic arrays, and the second superatomic array is composed of multiple second superatomic arrays;

[0007] The first superatom comprises a first metal layer, a first dielectric layer, an adhesive layer, a second metal layer, a second dielectric layer, and a third metal layer stacked together in sequence;

[0008] The first metal layer is a y-polarized isolation barrier, used to reflect y-polarized waves and transmit x-polarized waves;

[0009] The second metal layer consists of four identical open rings for polarization conversion, converting incident x / y polarized waves into y / x polarized waves;

[0010] The third metal layer is an x-polarized isolation barrier used to reflect x-polarized waves and transmit y-polarized waves;

[0011] The second superatom comprises a top metal layer, an intermediate dielectric layer, and a bottom metal layer stacked together in sequence;

[0012] The top metal layer consists of four identical metal open rings, which serve as polarization conversion, converting incident x / y polarized waves into y / x polarized waves.

[0013] The bottom metal layer serves as a metal ground, converting incident waves into reflected waves;

[0014] The first superatomic array is positioned above the second superatomic array and their centers coincide along the vertical direction; a preset number of second superatoms at the center of the second superatomic array are removed to place an open waveguide feed source, thus completing the design of the array antenna.

[0015] Preferably, the first superatom is polarization-sensitive to the incident wave, completely reflecting x-polarized incident waves and converting y-polarized incident waves into x-polarized waves for transmission; the opening angle of the opening ring through the second metal layer... and rotation angle By adjusting the phase, phase coverage can reach 360 degrees.

[0016] Preferably, the second superatom is insensitive to the polarization of the incident wave and functions as a polarization converter.

[0017] Preferably, both the first and second superatomic arrays are circular arrays and have the same size.

[0018] Preferably, removing the preset number of second superatoms specifically means removing 4 × 2.

[0019] Preferably, the dielectric constant of the first dielectric layer and the second dielectric layer is 2.65, and the loss tangent is 0.009.

[0020] Preferably, the dielectric constant of the adhesive layer is 3.2 and the loss tangent is 0.0041.

[0021] Preferably, the dielectric constant of the intermediate dielectric layer is 2.65 and the loss tangent is 0.009.

[0022] Preferably, the circular array radius of the first superatomic array and the second superatomic array is 40 mm; the distance between the first superatomic array and the second superatomic array is 15 mm.

[0023] According to a second aspect of the present invention, a design method for a broadband folded transmission array antenna that generates an OAM beam is provided, the method being applied to the broadband folded transmission array antenna that generates an OAM beam as described in any of the first aspects of the present invention, the method comprising:

[0024] With a center frequency of 30 GHz, the array phase distribution required to form the OAM beam satisfies the following formula: ,in, Let F be the wavenumber, and the array surface be equivalent to a two-dimensional plane xoy, where x and y are the coordinates of the first superatom on the xoy plane, and F is the focal length. The topological charge number of the OAM beam.

[0025] The beneficial effects of this invention are as follows:

[0026] As can be seen from the above scheme, the embodiments of the present invention provide a broadband folded transmission array antenna for generating OAM beams and a design method thereof, which have the following beneficial effects:

[0027] This application designs a broadband folded transmission array antenna (FTA) capable of generating OAM beams. The FTA consists of two metasurfaces (MS) with different functions and an open waveguide as a feed. Metasurface MS1 generates high-gain OAM within its operating bandwidth. Metasurface MS2 reflects and rotates the polarization of linearly polarized waves by 90°, covering the operating bandwidth of metasurface MS1. An open waveguide is used to feed the FTA at the center of metasurface MS2. Metasurface MS1 is provided by a first metaatomic array, and metasurface MS2 is provided by a second metaatomic array. Compared with other similar products, the broadband folded transmission array antenna of this application has a further reduced antenna profile, significantly increased bandwidth, higher efficiency, and greater stability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the first superatomic structure in a broadband folded transmission array antenna that generates an OAM beam, according to an embodiment.

[0029] Figure 2 This is a schematic diagram of a second superatomic structure in a broadband folded transmission array antenna that generates an OAM beam, according to an embodiment.

[0030] Figure 3 This is a schematic diagram illustrating the working principle of a broadband folded transmission array antenna that generates an OAM beam, according to an embodiment.

[0031] Figure 4 The scattering characteristics of a first superatom in a broadband folded transmission array antenna that generates an OAM beam, according to an embodiment;

[0032] Figure 5 The scattering characteristics of a second superatom in a broadband folded transmission array antenna that generates an OAM beam, according to an embodiment;

[0033] Figure 6 Analysis of near-field and far-field OAM characteristics;

[0034] Figure 7 This is a schematic diagram showing the changes of |S11|, gain, and aperture efficiency of the FTA with frequency.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1-First superatom, 11-First metal layer, 12-First dielectric layer, 13-Adhesive layer, 14-Second metal layer, 15-Second dielectric layer, 16-Third metal layer;

[0037] 2-Second superatom, 21-Top metal layer, 22-Intermediate dielectric layer, 23-Bottom metal layer. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0039] According to a first aspect of the present invention, a broadband folded transmission array antenna for generating OAM beams is provided, the array antenna comprising: a first superatomic array, a second superatomic array, and an open waveguide feed;

[0040] The first superatomic array is composed of multiple first superatomic arrays, and the second superatomic array is composed of multiple second superatomic arrays; the first superatomic array is positioned above the second superatomic array and their center projections coincide along the vertical direction; a preset number of second superatoms at the center of the second superatomic array are removed to place an open waveguide feed source, thus completing the design of the array antenna, which can generate an OAM beam.

[0041] OAM (orbital angular momentum) beams are electromagnetic beams that possess orbital angular momentum. Orbital angular momentum (OAM) is a fundamental property of electromagnetic waves, describing the characteristic of electromagnetic waves rotating around their propagation axis, causing the phase wavefront of the electromagnetic wave to exhibit a vortex-like shape. This type of electromagnetic wave is called a vortex electromagnetic wave.

[0042] The first superatom 1 was adjusted using Ansys HFSS (High Frequency Structure Simulator), a commercial electromagnetic simulation software from Ansoft. The first superatom is an artificial electromagnetic microstructure consisting of three metal layers and two dielectric layers. The dielectric layer material is F4BM265 (dielectric constant 2.65, loss tangent 0.009), and the two dielectric layers are separated by an adhesive layer (Rogers 4450F, dielectric constant 3.2, loss tangent 0.0041). The top metal layer is a y-polarized isolation barrier, reflecting y-polarized waves and transmitting x-polarized waves. The middle layer consists of four identical open rings, which perform polarization conversion, transforming incident x / y-polarized waves into y / x-polarized waves. The bottom layer is an x-polarized isolation barrier, reflecting x-polarized waves and transmitting y-polarized waves. Superatom 1 is polarization sensitive; it completely reflects x-polarized incident waves and converts y-polarized incident waves into x-polarized waves for transmission. The phase is adjusted by changing the opening angle and rotation angle of the intermediate metal layer opening ring, achieving a phase coverage of 360 degrees.

[0043] Specifically, such as Figure 1 As shown, the first superatom 1 includes a first metal layer 11, a first dielectric layer 12, an adhesive layer 13, a second metal layer 14, a second dielectric layer 15, and a third metal layer 16 stacked together in sequence.

[0044] The first metal layer 11 is a y-polarized isolation gate, used to reflect y-polarized waves and transmit x-polarized waves;

[0045] The second metal layer 14 consists of four identical open rings for polarization conversion, converting incident x / y polarized waves into y / x polarized waves;

[0046] The third metal layer 16 is an x-polarized isolation barrier used to reflect x-polarized waves and transmit y-polarized waves.

[0047] The second superatom 2 was simulated using Ansys HFSS software. The second superatom 2 is a reflective structure consisting of two metal layers and one dielectric layer. The dielectric layer material is F4BM265 (dielectric constant 2.65, loss tangent 0.009). The top metal layer consists of four identical open metal rings, which act as polarization converters, converting incident x / y polarized waves into y / x polarized waves. The bottom metal layer acts as a ground plane, converting incident waves into reflected waves. It is insensitive to the polarization of the incident wave, serving only a polarization conversion function and does not require 360-degree phase coverage; therefore, its structure is fixed.

[0048] Specifically, such as Figure 2As shown, the second superatom 2 includes a top metal layer 21, an intermediate dielectric layer 22 and a bottom metal layer 23 stacked together in sequence;

[0049] The top metal layer 21 consists of four identical metal open rings, which play a polarization conversion role, converting the incident x / y polarized wave into a y / x polarized wave.

[0050] The bottom metal layer 23 serves as a metal ground, converting incident waves into reflected waves.

[0051] The first superatom is polarization-sensitive to the incident wave; it completely reflects x-polarized incident waves and converts y-polarized incident waves into x-polarized waves for transmission. The opening angle of the opening ring in the second metal layer 14... and rotation angle By adjusting the phase, phase coverage can reach 360 degrees.

[0052] The second superatom is insensitive to the polarization of the incident wave and functions as a polarization converter.

[0053] Both the first and second superatomic arrays are circular arrays and have the same size.

[0054] The removal of the preset number of second superatoms specifically refers to the removal of 4 × 2.

[0055] The dielectric constant of the first dielectric layer 12 and the second dielectric layer 15 is 2.65, and the loss tangent is 0.009.

[0056] The dielectric constant of the adhesive layer 13 is 3.2, and the loss tangent is 0.0041.

[0057] The dielectric constant of the intermediate dielectric layer 22 is 2.65, and the loss tangent is 0.009.

[0058] The first and second superatomic arrays both have a circular array radius of 40 mm; the distance between the first and second superatomic arrays is 15 mm. The first superatomic array consists of 256 superatoms 1, and the second superatomic array consists of 248 (256 minus 8) superatoms 2. Both are circular arrays with a radius of 40 mm. For fixation, eight nylon pillars and screws are used for secure installation. The actual distance between PG and PC is 15 mm.

[0059] This application designs a broadband folded transmission array antenna (FTA) capable of generating OAM beams. The FTA consists of two metasurfaces (MS) with different functions and an open waveguide as a feed. Metasurface MS1 generates high-gain OAM within its operating bandwidth. Metasurface MS2 reflects and rotates the polarization of linearly polarized waves by 90°, covering the operating bandwidth of metasurface MS1. An open waveguide is used to feed the FTA at the center of metasurface MS2. Metasurface MS1 is provided by a first metaatomic array, and metasurface MS2 is provided by a second metaatomic array. Compared with other similar products, the broadband folded transmission array antenna of this application has a further reduced antenna profile, significantly increased bandwidth, higher efficiency, and greater stability.

[0060] According to a second aspect of the present invention, a design method for a broadband folded transmission array antenna that generates an OAM beam is provided, the method being applied to the broadband folded transmission array antenna that generates an OAM beam as described in any one of Embodiments 1; the method is as follows:

[0061] The opening angle of the metal interlayer opening ring of the first superatom 1 and rotation angle It can be adjusted to provide 360-degree phase coverage, ensuring that the first superatom 1 can provide phase compensation. The structures of the first and second superatoms are fixed, and they only need to provide polarization conversion functionality.

[0062] like Figure 1 As shown, the specific parameters of the first superatom 1 are: p = 4, l1 = 0.53, l2 = 0.47, h1 = 0.035, h2 = 0.2, h3 = 0.8, r = 0.94, w = 0.13, unit: millimeters.

[0063] The specific parameters of the second superatom 2 are: p = 4, h4 = 1.2, r1 = 0.94, w0 = 0.13, in millimeters. Alpha1 = 120 degrees.

[0064] With a center frequency of 30 GHz, the array phase distribution required to form the OAM beam satisfies the following formula: ,in, Let F be the wavenumber, and the array surface be equivalent to a two-dimensional plane xoy, where x and y are the coordinates of the first superatom on the xoy plane, and F is the focal length. The topological charge number of the OAM beam.

[0065] Working principle:

[0066] Combination Figure 3As shown in Figure (b), the open waveguide feed emits an x-polarized wave (ray 1). Ray 1 is completely reflected by PG (first atomic array layer), and the reflected wave (ray 2) reaches PCR. PCR (second atomic array layer) converts the reflected wave (ray 2) into a reflected wave (ray 3), which is then converted into a y-polarized wave and reaches PG (first atomic array layer). PG (first atomic array layer) allows the y-polarized wave to pass through. PG (first atomic array layer) provides phase compensation, ultimately generating the OAM beam. Therefore, the distance between PG (first atomic array layer) and PCR (second atomic array layer) is shortened to 1 / 3 of the original focal length.

[0067] The results indicate that:

[0068] 1) From Figure 4 As can be seen in Figure (a), the first superatom 1 almost completely converts the y-polarized incident wave into an x-polarized wave and transmits it. From Figure 4 As can be seen in Figure (b), only changes are needed at 30GHz. and It can achieve 360-degree phase coverage without the need for an additional resonant layer. Figure 4 Figures (c) and (d) in the text show different... and When the frequency changes, both the amplitude and phase change with the frequency. Figure 4 Figure (e) shows the transmission characteristics of the first superatom 1 under oblique incidence. This error is acceptable. Figure 4 Figure (f) illustrates the working principle of the first superatom 1. The y-polarized wave undergoes multiple reflections and transmissions before finally being converted into an x-polarized wave for emission. This is the reason for the superatom's broadband and high-efficiency characteristics. Furthermore, Figure 5 The scattering properties of the second superatom 2.

[0069] 2) From Figure 6 Figures (a), (b), and (c) show the near-field amplitude, phase, and normalized OAM purity of the metasurface. It can be seen that the electric field is a hollow ring, consistent with the electric field distribution of the metasurface. The phase distribution shows that the number of spiral arms is one, rotating clockwise, thus the topological charge of the metasurface is +1. The normalized OAM purity distribution reveals weak alternative OAM modes at frequencies far from the center frequency. Due to the inherent dispersion of the metasurface, the function deviates from the pre-designed function at frequencies far from the design center frequency. Figure 6 d provides the far-field radiation pattern of the yoz plane, which also shows the chromatic aberration problem.

[0070] 3) Figure 7Figure (a) in the figure shows the |S11| of the FTA. It can be seen that at the operating frequency, |S11| is less than -10dB, which shows good impedance matching. Figure 7 b gives the gain and aperture efficiency of the FTA, and it can be seen that its gain and aperture efficiency are stable within the operating bandwidth.

[0071] In summary, this application employs a polarization conversion transmission unit as a polarization isolation grid, achieving a -1dB bandwidth of 21.4%, successfully solving the problems of narrow bandwidth and low efficiency of FTA used for generating OAM. Furthermore, the FTA of this application has a lower profile and a focal diameter ratio of only 0.225, while the focal diameter ratio of traditional space feeds is generally between 0.55 and 1.

[0072] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A broadband folded transmission array antenna for generating OAM beams, characterized in that, The array antenna includes: a first superatomic array, a second superatomic array, and an open waveguide feed source; The first superatomic array is composed of multiple first superatomic arrays, and the second superatomic array is composed of multiple second superatomic arrays; The first superatom comprises a first metal layer, a first dielectric layer, an adhesive layer, a second metal layer, a second dielectric layer, and a third metal layer stacked together in sequence; The first metal layer is a y-polarized isolation barrier, used to reflect y-polarized waves and transmit x-polarized waves; The second metal layer consists of four identical open rings for polarization conversion, converting incident x / y polarized waves into y / x polarized waves; The third metal layer is an x-polarized isolation barrier used to reflect x-polarized waves and transmit y-polarized waves; The second superatom comprises a top metal layer, an intermediate dielectric layer, and a bottom metal layer stacked together in sequence; The top metal layer consists of four identical metal open rings, which serve as polarization conversion, converting incident x / y polarized waves into y / x polarized waves. The bottom metal layer serves as a metal ground, converting incident waves into reflected waves; The first superatomic array is positioned above the second superatomic array and their center projections coincide along the vertical direction; a preset number of second superatoms at the center of the second superatomic array are removed to place an open waveguide feed source, thus completing the design of the array antenna; The first superatom is polarization-sensitive to the incident wave; it completely reflects x-polarized incident waves and converts y-polarized incident waves into x-polarized waves for transmission; the opening angle of the opening ring of the second metal layer... and rotation angle The phase is adjusted to achieve 360-degree phase coverage; The second superatom is insensitive to the polarization of the incident wave and functions as a polarization converter; Both the first and second superatomic arrays are circular arrays and have the same size; Removing the preset number of second superatoms specifically means removing 4 × 2; The dielectric constant of the first dielectric layer and the second dielectric layer is 2.65, and the loss tangent is 0.

009. The dielectric constant of the adhesive layer is 3.2, and the loss tangent is 0.0041. The dielectric constant of the intermediate dielectric layer is 2.65, and the loss tangent is 0.

009.

2. The broadband folded transmission array antenna for generating OAM beams according to claim 1, characterized in that, The first and second superatomic arrays both have a circular array radius of 40 mm; the distance between the first and second superatomic arrays is 15 mm.

3. A design method for a broadband folded transmission array antenna that generates an OAM beam, characterized in that, The design method is applied to the broadband folded transmission array antenna for generating OAM beams as described in any one of claims 1-2, and the method includes: With a center frequency of 30 GHz, the array phase distribution required to form the OAM beam satisfies the following formula: ,in, Let F be the wavenumber, and the array surface be equivalent to a two-dimensional plane xoy, where x and y are the coordinates of the first superatom on the xoy plane, and F is the focal length. This represents the topological charge number of the OAM beam.

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