A Three-Band Multifunctional Antenna Based on a Codified Metasurface

Abstract

This invention discloses a three-band multi-functional antenna based on a coded metasurface, comprising a feed source and a radiating structure for reflection. The feed source is positioned above the radiating structure, which includes a dielectric substrate. The top layer of the substrate contains 30×30 metal patch elements arranged in an array, and a metal ground plane is positioned below. Each metal patch element consists of three sets of symmetrically arranged internal phase delay lines, a central phase delay line, and an external phase delay line, all symmetrical about the center. They operate in the C, Ku, and X bands respectively and can be applied to downlink and high-speed satellite communications. The use of a coded metasurface enables multi-frequency, multi-mode OAM multiplexing and beamforming functions, demonstrating significant potential application value.

Description

Technical Field

[0001] This invention belongs to the field of antennas in communication systems, and in particular to a three-band multifunctional antenna based on a coded metasurface. Background Technology

[0002] Since its introduction in 2014, coded metamaterials have seen extensive applications in the digital manipulation of electromagnetic waves, including reflective, transmissive, and even full-space electromagnetic manipulation, anisotropic metasurfaces, and acoustically coded metasurfaces. Among these, the informational properties of digitally coded metasurfaces are particularly noteworthy. The information of a digitally coded metasurface is concentrated in its coded pattern; different coded patterns produce different scattered electromagnetic fields. Therefore, the analysis of the coded pattern's information is linked to the scattering characteristics of the coded metasurface. However, in practical applications, the far-field radiation patterns generated by different coded metasurface antennas are difficult to receive completely, with a significant amount of information hidden in the sidelobes and lost. Compared to traditional plane electromagnetic waves, vortex electromagnetic waves carrying orbital angular momentum (OAM) are unique beams with a helical phase structure and a ring-shaped amplitude field. Due to the infinity of OAM modes and the orthogonality between different modes, they provide a new degree of freedom independent of the time, frequency, and polarization domains. OAM waves have great potential for channel expansion and improving spectral efficiency.

[0003] Although significant progress has been made in the research of multi-band and multi-functional metasurfaces, the combination of traditional beamforming functions with multi-band OAM multiplexing functions is still rare. Furthermore, the generation of multi-mode OAM beams in multiple frequency bands through metasurfaces often involves complex structures, using two or more layers of dielectric material or complex patch shapes that are prone to damage. In addition, the arraying methods used are more complex than those of coded metasurfaces. Moreover, the multi-frequency OAM beam generation function of metasurfaces is mostly limited to higher frequency bands such as X, Ku, and Ka. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a three-band multi-functional antenna device based on a coded metasurface, which can generate different modes of OAM vortex electromagnetic waves at 7GHz and 10GHz through 2-bit coded metasurface units, and achieve beam modulation function at 17GHz.

[0005] The technical solution of the present invention is as follows: A reflective metasurface device that generates dual-frequency OAM vortex waves based on coded metasurfaces and realizes high-frequency beam control, including a feed source and a radiation structure that realizes the reflection function. It is characterized in that the feed source is arranged above the radiation structure; the radiation structure includes: a dielectric substrate and M×N metal patch units arranged in an array on its top layer, and a metal ground plane is arranged below the dielectric substrate; the metal patch units are configured to be composed of three groups of internal phase delay lines, middle phase delay lines, and external phase delay lines that are symmetric figures.

[0006] Preferably, the internal phase delay line is in the shape of a "+", and the width is fixed at 0.4 mm, operating at 10 GHz, and the phase of the reflected electromagnetic wave is changed by adjusting the length.

[0007] Preferably, the middle phase delay line and the internal phase delay line are combined into a "rice" shape, the width is fixed at 0.5 mm, operating at 17 GHz, and the phase of the reflected electromagnetic wave is changed by adjusting the length.

[0008] Preferably, the external phase delay line and the internal phase delay line are combined into a "field" shape, the width is fixed at 0.5 mm, operating at 7 GHz, and the phase of the reflected electromagnetic wave is changed by adjusting the length.

[0009] Preferably, the internal, middle, and external phase delay lines are all centrosymmetric and applicable to all-polarization electromagnetic waves.

[0010] Preferably, when electromagnetic waves are incident on the metasurface, by adjusting the corresponding parameters, the phase change of the reflected electromagnetic wave in the corresponding band can be controlled. When operating at 7 GHz, control the lengths of the external phase delay lines to be 4.5, 5.3, 5.5, 5.9, and the phase differences are all 90°, forming a 2-bit coded metasurface. Through phase compensation calculation and array arrangement, a first-order OAM beam is generated; when operating at 10 GHz, control the lengths of the internal phase delay lines to be 4.11, 4.36, 4.49, 4.93, and the phase differences are all 90°, forming a 2-bit coded metasurface. Through phase compensation calculation and array arrangement, a +2-order OAM beam is generated; when operating at 17 GHz, control the lengths of the middle phase delay lines to be 1.8, 2.3, 3.3, 3.9, and the phase differences are all 90°, forming a 2-bit coded metasurface, and the beam control function is realized.

[0011] Preferably, the array shape formed by the arrangement of the metal patch units is square.

[0012] The present invention has the following advantages:

[0013] (1) The reflective metasurface achieves nearly 360° phase coverage in the 7, 10 and 17 frequency bands and has a high reflection amplitude. The 2-bit encoded metasurface method bridges the gap between information science and physics, making the array arrangement very convenient and facilitating the realization of functions.

[0014] (2) This reflective metasurface realizes multi-frequency OAM multiplexing and is not limited to Ku, Ka and other frequency bands. It can also realize OAM beam generation in C and X frequency bands and can be applied to satellite communication and other fields.

[0015] (3) The design of the reflective metasurface is flexible. It achieves OAM beam generation of l=+1 and l=+2 at 7 and 10 GHz, and beam modulation at 17 GHz. The coupling between different bands is small, which can realize multi-band independent phase control of the reflected beam and also ensure that the functions do not interfere with each other.

[0016] (4) The reflective metasurface has a simple structure, using only a single-layer dielectric substrate and a metal patch. The metal patch has a simple shape, is not easily damaged, is easy to process and assemble, and has the advantage of a low profile. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the metasurface unit of the present invention;

[0018] Figure 2 This is a schematic diagram of the reflective antenna array constructed according to the present invention;

[0019] Figure 3 This is the reflection phase diagram of the present invention at 7GHz when the three parameters change according to 2-bit encoding;

[0020] Figure 4 This is the reflection phase diagram of the present invention at 10 GHz when the three parameters change according to 2-bit encoding.

[0021] Figure 5 This is the reflection phase diagram of the present invention at 17GHz when the three parameters change according to 2-bit encoding.

[0022] Figure 6 (a) and (b) represent the phase compensation amounts required by the present invention to generate the metasurface units at various positions of the OAM beam at 7 and 10 GHz, respectively.

[0023] Figure 7 This is a schematic diagram illustrating the beam control function implemented by the present invention at 17GHz;

[0024] Figure 8 (a) and (b) are the far-field patterns of the OAM beams with l = +1 and l = +2 generated by the present invention, respectively;

[0025] Figure 9 (a) and (b) are respectively the electric field intensity and phase distribution diagrams of the OAM beam with l = +1 generated by the present invention at 7 GHz;

[0026] Figure 10 (a) and (b) are respectively the electric field intensity and phase distribution diagrams of the OAM beam with l = +2 generated by the present invention at 10 GHz; Detailed implementation manners

[0027] The present invention will be further described in detail below with reference to the accompanying drawings.

[0028] Embodiment

[0029] As Figure 1 、 Figure 2 shown, the present invention discloses a triple - band multifunctional antenna based on a coded metasurface, including a feed source and a radiation structure for realizing the reflection function. The feed source is arranged above the radiation structure. The radiation structure includes a dielectric substrate. M×N metal patch units arranged in an array are provided on the top layer of the dielectric substrate, and a metal ground plane is provided below. The metal patch unit is composed of three groups of internal phase delay lines, middle phase delay lines, and external phase delay lines that are symmetric figures, and they are all centrosymmetric.

[0030] The three groups of phase delay lines work at different frequencies respectively. The internal phase delay line is in a "+" shape, and the width w1 is fixed at 0.4 mm, working at 10 GHz. When the length l1 is 4.5, 5.3, 5.5, 5.9, the phase difference is 90°, forming a 2 - bit coded metasurface; the middle phase delay line and the internal phase delay line are combined into a "cross" shape, the width w2 is fixed at 0.5 mm, working at 17 GHz. When the length l2 is 4.11, 4.36, 4.49, 4.93, the phase difference is 90°, forming a 2 - bit coded metasurface; the external phase delay line and the internal phase delay line are combined into a "square" shape, the width w3 is fixed at 0.5 mm, working at 7 GHz. When the length l3 is 1.8, 2.3, 3.3, 3.9, the phase difference is 90°, forming a 2 - bit coded metasurface. The metal patch unit is printed on a TF - 2 (εr = 14) dielectric substrate with a thickness h1 = 1.5 mm and a period of 12 mm. At 7 GHz, the feed source is incident on the metasurface at θ = 0, ψ = 25° with the phase center 300 mm away from the center of the metasurface reflection array, where θ and ψ respectively represent the elevation angle and azimuth angle. At 10 GHz, the feed source is incident on the metasurface at θ = 0, ψ = 25° with the phase center 300 mm away from the center of the metasurface reflection array. At 17 GHz, the feed source is vertically incident on the metasurface with the phase center 350 mm away from the metasurface reflection array respectively. The length and width of the metasurface array are both 360 mm.

[0031] The feed source can be a microstrip antenna or a horn antenna, which are linearly polarized antennas with low sidelobes and low backlobes.

[0032] The required phase compensation for a radiating element is related to its position on the upper surface of the dielectric substrate. Different phase compensations are calculated based on the generation of different OAM vortex wave modes. The principle of generating OAM electromagnetic waves in the reflective supermassive OAM antenna of this invention, with the array center as the origin, can be explained by the following formula:

[0033] Where λ is the wavelength of the incident wave, d mn It is the distance from the center of the array to the equivalent phase center of the feed, and l is the mode number of the OAM vortex wave.

[0034] In this example, 30×30 radiating elements are periodically arranged to form a multifunctional reflective metasurface, with a size of 360mm×360mm. First, the phase compensation required for a feed incident on the metasurface at θ=0, ψ=25° at a position 300mm from the center of the metasurface reflective array at 7GHz is calculated. Then, the phase compensation required to generate the l=1 mode OAM beam is added, as follows: Figure 6 As shown in (a). Using the same method, the phase compensation required to generate a l=+2 mode OAM beam at 10 GHz can be calculated, such as... Figure 6 As shown in (b). Finally, the internal structure, middle structure, and external structure are arranged and combined to form a three-frequency multifunctional reflective metasurface, as shown in [the diagram]. Figure 2 As shown. The feed is perpendicularly incident at 17 GHz, so we only need to calculate the phase compensation when θ = 0 and ψ = 0, and then apply the formula... Where λ is the wavelength of the incident wave, Γ is the period of the coded metasurface, and the phase compensation amount required to deflect the beam direction is added to obtain the desired beam control result. The calculated phase compensation results are substituted into the algorithm code of MATLAB software at 7GHz, 10GHz, and 17GHz, and the corresponding 2-bit cell arrays are arranged for simulation. Figure 8 (a) Figure 8 (b) Three-dimensional radiation patterns at operating frequencies of 7 GHz and 10 GHz. The three-dimensional radiation patterns show that the OAM vortex beams generated at 7 GHz and 10 GHz both exhibit relatively obvious hollow characteristics, i.e., a zero-intensity center caused by a phase singularity. The maximum gains of the l=+1 mode at 7 GHz and the l=+2 mode at 10 GHz are 16.6 dBi and 19.8 dBi, respectively. Figure 9 (a) and Figure 9 (b) shows the electric field intensity and phase distribution of the vortex wave generated at 7 GHz, respectively. Figure 9 As can be seen from (a), the electric field exhibits a hollow characteristic. Figure 9 As can be seen in (b), the phase exhibits a counterclockwise spiral distribution, i.e., generating a beam of OAM vortex waves in the l=+1 mode. Similarly, Figure 10 (a) Figure 10 (b) shows the electric field intensity and phase distribution of the vortex wave generated at 10 GHz, i.e., the OAM vortex wave of l=+2 mode was generated at 10 GHz. Figure 7 The beamforming capability of the metasurface at 17 GHz was demonstrated, with the beamforming result achieved through encoding "00112233…". Figure 7 As shown in (a) and (b), with a deflection angle of 10°, the wavelength is 17.6 mm and the period Γ is 96 mm; simultaneously, the dual-beam generation function is achieved, as shown in... Figure 7 As shown in (c) and (d), the deflection angles of the two beams are equal. Therefore, the designed reflective metasurface can simultaneously realize various functions in three frequency bands, achieving multi-mode OAM multiplexing under multiple frequencies and controlling beam pointing.

[0035] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0036] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A three-band multi-functional antenna based on a coded metasurface, characterized in that, It includes a feed source and a radiation structure that realizes the reflection function; The feed source is arranged above the radiation structure; the radiation structure includes: a dielectric substrate and M×N metal patch units arranged in an array on its top layer, and a metal ground plane is arranged below the dielectric substrate; The metal patch units are configured as follows: they are composed of three groups of internal phase delay lines, middle phase delay lines, and external phase delay lines that are symmetric figures; the three groups of phase delay lines work at different frequencies. The internal phase delay line is in a "+" shape, and the width w1 is fixed at 0.4 mm and works at 10 GHz. When the length l1 is 4.5, 5.3, 5.5, 5.9, the phase difference is 90°, forming a 2-bit coded metasurface; the middle phase delay line and the internal phase delay line are combined into a "rice" shape, the width w2 is fixed at 0.5 mm and works at 17 GHz. When the length l2 is 4.11, 4.36, 4.49, 4.93, the phase difference is 90°, forming a 2-bit coded metasurface; the external phase delay line and the internal phase delay line are combined into a "field" shape, the width w3 is fixed at 0.5 mm and works at 7 GHz. When the length l3 is 1.8, 2.3, 3.3, 3.9, the phase difference is 90°, forming a 2-bit coded metasurface.

2. The three-band multi-functional antenna based on a coded metasurface according to claim 1, characterized in that, At 7 GHz, the feed source is incident on the metasurface at θ = 0, ψ = 25° with the phase center 300 mm away from the center of the metasurface reflection array. Here, θ and ψ respectively represent the magnitudes of the elevation angle and the azimuth angle. At 10 GHz, the feed source is incident on the metasurface at θ = 0, ψ = 25° with the phase center 300 mm away from the center of the metasurface reflection array. At 17 GHz, the feed source is vertically placed and perpendicularly incident on the metasurface with the phase center 350 mm away from the metasurface reflection array respectively. The length and width of the metasurface array are both 360 mm.

3. A three-band multi-functional antenna based on a coded metasurface according to claim 1, characterized in that, When incident waves of different frequencies are incident at corresponding angles, first calculate the phase compensation required to achieve the desired function, and then adjust the lengths of the internal, middle, and external phase delay lines. Using the 2-bit coded metasurface component array, the metasurface antenna generates OAM beams in the l = +1 and l = +2 modes at 7 and 10 GHz, and realizes the beam steering function at 17 GHz.

4. A three-band multi-functional antenna based on a coded metasurface according to claim 1, characterized in that, The array shape formed by the arrangement of the metal patch units is square.

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