Huygens metasurface loaded low profile beam regulation millimeter wave antenna

Abstract

The invention discloses a Huygens metasurface loaded low-profile beam regulation millimeter wave antenna, which comprises a non-biased substrate integrated waveguide slot array antenna and a near-field Huygens metasurface, the non-biased substrate integrated waveguide slot array antenna is composed of a first dielectric substrate, metal structures printed on the top and the bottom of the first dielectric substrate, slot arrays etched on the metal structures, and metal through holes in the first dielectric substrate. The near-field Huygens metasurface comprises a second dielectric substrate and metal structures at the top and the bottom of the second dielectric substrate; the non-biased substrate integrated waveguide slot array antenna serves as an excitation source and is used for providing spherical waves, and the near-field Huygens metasurface is used for accurately regulating and controlling phase distribution above the slot array antenna. The metasurface antenna has the characteristic of low profile, and two-dimensional wave beam regulation and control can be realized based on different metasurface distributions.

Description

Technical Field

[0001] The present invention relates to the application field of metasurface antennas, and in particular to a low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface. Background Art

[0002] Metasurface antenna is an emerging microwave and optical antenna technology. Using metasurface to control the wavefront of antenna is a very effective means. Metasurface is composed of a large number of subwavelength-scale structural units, which can adjust the phase, amplitude and polarization characteristics of waves. Compared with traditional antennas, metasurface antennas are not only smaller in size and lighter in weight, but also have significant advantages in radiation directivity, gain and versatility. This technology shows broad application prospects in 5G communications, radar systems and lossless imaging.

[0003] A common application of metasurfaces is to steer beams in radiation patterns. In this case, a horn antenna is used as an excitation source and a metasurface is placed far enough above it so that the incident wave can be approximated as a plane wave, but this characteristic leads to an increase in the antenna profile height. In recent years, many reports have explored the use of near-field metasurfaces to steer beams, in which the metasurface is located in the near-field region of the antenna. However, due to the arrangement of the metasurface, two-dimensional beam direction control cannot be achieved. Summary of the invention

[0004] The purpose of the present invention is to provide a low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface, which is used to solve the problem that the metasurface antenna has a too high profile height and that two-dimensional beam steering cannot be achieved using a near-field Huygens metasurface. The Huygens response of a near-field metasurface unit and the open-stopband suppression of a non-biased substrate integrated waveguide slot array antenna are explained in principle.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface, including a non-biased substrate integrated waveguide slot array antenna and a near-field Huygens metasurface; the non-biased substrate integrated waveguide slot array antenna is composed of a first dielectric substrate, a metal structure printed on the top and bottom of the first dielectric substrate, a slot array etched on the metal structure, and a metal through hole in the first dielectric substrate; the near-field Huygens metasurface includes a second dielectric substrate, and metal structures on the top and bottom of the second dielectric substrate.

[0006] Furthermore, the first dielectric substrate is Arlon AD250A, with a thickness of 0.762 mm.

[0007] Furthermore, the metal structural material at the top and bottom of the first dielectric substrate is copper with a thickness of 0.035 mm.

[0008] Furthermore, the rectangular slot array is periodically arranged at a pitch of 5 mm at the center of the metal structure on the top of the first dielectric substrate. These rectangular slots together constitute an 8*8 rectangular slot array. The size of a single slot is 3.57 mm*0.90 mm. Several metal through holes are arranged around the slots.

[0009] Furthermore, the metal through holes have a diameter of 0.4 mm and a height of 0.762 mm. The direction along the long side of the rectangular slot is the y direction. The metal through holes at a certain distance from the slot array along the negative y direction together form a 1-to-8 power divider, and the other part is distributed around the slot array.

[0010] Furthermore, the second dielectric substrate material in the Huygens metasurface is Arlon AD250A, with a thickness of 1.524 mm.

[0011] Furthermore, the metal structures at the top and bottom of the near-field Huygens are composed of a pair of bias dipoles. Figure 3 Shown is a schematic diagram of the structure of the Huygens metasurface unit. The material of these dipoles is copper with a thickness of 0.035 mm.

[0012] Furthermore, a near-field Huygens metasurface is placed 0.762 mm above the non-biased substrate integrated waveguide slot array antenna.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) In order to solve the problem of high profile height of previous millimeter-wave metasurface antennas, this paper proposes a new low-profile metasurface antenna consisting of a non-biased substrate integrated waveguide slot array antenna and a near-field Huygens metasurface unit. Its profile height is only 3.2 mm (0.32λ, where λ is the operating wavelength).

[0015] (2) In order to address the problem that two-dimensional beam control could not be achieved using near-field metasurfaces in the millimeter wave frequency band, the present invention proposes a metasurface antenna that can operate in the millimeter wave frequency band, has a center frequency of 30 GHz, and can achieve two-dimensional beam scanning based on different metasurface distributions, thereby ensuring that the beam can be effectively controlled in the millimeter wave frequency band.

[0016] (3) In order to address the problem that metasurface antennas that can achieve two-dimensional beam control have too many layers, the present invention proposes a double-layer metasurface antenna that can perform two-dimensional beam scanning and does not require any additional dielectric layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a structural diagram of a low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface in the present invention.

[0018] Figure 2Schematic diagram of a non-biased substrate integrated waveguide slot array antenna.

[0019] Figure 3 Schematic diagram of the structure of the Huygens metasurface unit.

[0020] Figure 4 This is a schematic diagram of the antenna structure of the present invention using a low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface to achieve three different beam pointing directions.

[0021] Figure 5 This is a physical picture of the processing of the low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface in the present invention.

[0022] Figure 6 From left to right are the radiation pattern comparison diagrams of antenna simulation and test when the present invention uses a low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface to realize three different beams.

[0023] Figure 7 This is a comparison diagram of antenna gain of the simulation and test of the low-profile beam-steering millimeter-wave antenna loaded with Huygens metasurface in the present invention. DETAILED DESCRIPTION

[0024] In recent years, using metasurfaces to control the wavefront of antennas has become a very effective method. In the context of millimeter-wave applications, metasurfaces are often used to control beams in radiation patterns, but in this case, a horn is usually required as an excitation source, which has the disadvantage of being too high in overall profile height. At the same time, many studies have used near-field Huygens metasurfaces to control beams, but most of them are not suitable for millimeter-wave frequency bands. Millimeter-wave metasurface antennas that can solve both of the above problems have become a difficulty now.

[0025] like Figure 1 to Figure 3 As shown, the present invention provides a low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface, comprising a non-biased substrate integrated waveguide slot array antenna 1 and a near-field Huygens metasurface 2. The non-biased substrate integrated waveguide slot array antenna 1 is used as an excitation source to provide a spherical wave, and the near-field Huygens metasurface 2 can accurately control the phase distribution above the slot array antenna.

[0026] First, a non-biased substrate integrated waveguide slot array antenna 1 is designed. The non-biased substrate integrated waveguide slot array antenna 1 includes a 0.762mm thick Arlon AD250A first dielectric substrate 3; a metal structure 4 printed on the top and bottom of the first dielectric substrate, with a thickness of 0.035mm; a rectangular slot array 5 etched at the center of the metal structure surface on the top of the first dielectric substrate. The path width of the substrate integrated waveguide and the distance between adjacent slots are both 5mm, and the size of a single slot is 3.57mm×0.90mm. The long side direction of the rectangular slot is the y direction, and the short side direction of the matrix slot is the x direction. A metal through hole 6 is inserted 1.59mm away from the center of the matrix slot array along the x direction to change the current distribution, so that the slot can effectively destroy the surface current and promote radiation. Figure 2 The figure shows the schematic diagram of the non-biased substrate integrated waveguide slot array antenna. To further illustrate the principle of the proposed non-biased slot array, we designed a two-port non-biased slot array. The input port is far away from the radiating slot to reduce the influence of the excitation. The de-embedding technique is used to eliminate unnecessary transmission line effects. In the range of 28-32GHz, the beam continues to scan from back to front, indicating that the open stop band (OSB) is effectively suppressed. Next, we use the effective phase constant and attenuation constant to further analyze the suppression of the open stop band (OSB). The S parameters obtained by HFSS can be easily calculated, and the relationship is as follows:

[0027]

[0028] Where 4p represents the total length of the non-biased slot array, α is the attenuation constant, β is the phase constant, and S 11 , S 12 , S 21 , S 22 Representing S parameters, the combination of slots and through holes eliminates the OSB effect of the non-biased slot array. We can effectively remove the OSB effect by optimizing the position of the through holes on the x-axis so that the beam can scan from back to front.

[0029] Next, we design the Huygens metasurface, which consists of an ArlonAD250A second dielectric substrate 7 with a thickness of 1.524 mm and a metal structure 8 printed on the surface of the second dielectric substrate. The metal structure 8 consists of a pair of bias dipoles, and the bias dipole material is 0.035 mm thick copper. Figure 3 The figure shows the schematic diagram of the structure of the Huygens metasurface unit. In order to explore the resonance characteristics of the proposed Huygens unit, the sheet admittance Y es and the impedance Z of the magnetic sheet ms The relationship is as follows:

[0030]

[0031] Where η is the intrinsic impedance of free space, R is the complex reflection coefficient, and T is the complex transmission coefficient. When the real parts of the electric sheet admittance and magnetic sheet impedance are approximately 0, a transmission peak excited by electromagnetic resonance will be generated, satisfying the formula:

[0032] Y es η=Z ms / η

[0033] To further investigate the resonance phenomenon, we observed the current distribution on the surfaces of the two dipoles and found that they alternately generate electric and magnetic resonances, which together contribute to the Huigenst properties of the unit cell.

[0034] Finally, the near-field Huygens metasurface is placed 0.762 mm above the non-biased substrate integrated waveguide slot array antenna for integration, completing the design of a low-profile beam-steering millimeter-wave antenna loaded with Huygens metasurface. According to phased array theory, beam pointing Where θ0 represents the beam pointing in the elevation plane,

[0035] The beam pointing in the azimuth plane can be calculated by the following formula:

[0036]

[0037]

[0038] In the formula (φ x ,φ y ) represents the gradient phase difference between the x-direction and the y-direction, (d x ,d y ) represents the distance between adjacent units in the x-direction and the y-direction. According to the desired beam pointing, the distance and gradient phase difference between adjacent metasurface units are calculated.

[0039] The present invention will be further described in detail below in conjunction with specific embodiments with reference to the accompanying drawings.

[0040] Example 1

[0041] Figure 4 Schematic diagram of the antenna structure of the present invention for achieving 3 different beam pointings, Figure 5The actual pictures of the four antennas processed by the present invention, the antennas with three different beam directions of the present invention are all composed of non-biased substrate integrated waveguide slot array antennas and near-field Huygens metasurfaces, and the overall profile height is 3.2mm. Compared with antenna 2, antenna 1 does not contain the Huygens metasurface covered on the slot array antenna. The Huygens metasurface in antenna 2 is composed of a dielectric substrate and metal structures at the top and bottom of the dielectric substrate. The metal structure is composed of a pair of biased dipoles, along the long side direction of the rectangular slot is the y direction, along the short side direction of the matrix slot is the x direction, and the short sides of the dipoles in the third and seventh columns along the x direction have smaller central angles than those in other columns. Figure 6 This is a comparison diagram of the radiation pattern of the present invention, which is simulated and measured. Figure 7 The simulation and test comparison diagrams of antenna gain with three different beam directions are given. It can be observed from these figures that when the center frequency of antenna 2 is 30 GHz, a beam direction of 30° is achieved on the H plane, the cross polarization is lower than -15 dB, the gain during simulation is 18.2 dBi, the measured gain is 16.5 dBi, the radiation efficiency is 71%, and the -10 dB bandwidth is 2%. The three antennas of the present invention are compared with the non-biased substrate integrated waveguide slot array antenna 1, and it is found that after the incorporation of the metasurface, the gain deviation range is 1.7 dBi to 2.6 dBi.

[0042] Example 2

[0043] Figure 4 Schematic diagram of the antenna structure of the present invention for achieving 3 different beam pointings, Figure 5 The actual pictures of the four antennas processed by the present invention, the antennas with three different beam directions of the present invention are all composed of non-biased substrate integrated waveguide slot array antennas and near-field Huygens metasurfaces, and the overall profile height is 3.2mm. Compared with antenna 3, antenna 1 does not contain a Huygens metasurface covered on the slot array antenna. The Huygens metasurface in antenna 3 is composed of a dielectric substrate and metal structures at the top and bottom of the dielectric substrate. The metal structure is composed of a pair of biased dipoles, along the long side direction of the rectangular slot is the y direction, along the short side direction of the matrix slot is the x direction, and the short sides of the dipoles in the third and seventh columns along the y direction have smaller central angles than other columns. Figure 6 This is a comparison diagram of the radiation pattern of the present invention, which is simulated and measured. Figure 7The simulation and test comparison diagrams of antenna gain with three different beam directions are given. It can be observed from these figures that when the center frequency of antenna 3 is 30 GHz, a beam direction of approximately -29° is achieved on the E plane, the cross polarization is much lower than -20 dB, the gain during simulation is 19.2 dBi, the measured gain is 17.5 dBi, the radiation efficiency is 63%, and the -10 dB bandwidth is 1%. The three antennas of the present invention are compared with the non-biased substrate integrated waveguide slot array antenna 1, and it is found that after the incorporation of the metasurface, the gain deviation range is 1.7 dBi to 2.6 dBi.

[0044] Example 3

[0045] Figure 4 Schematic diagram of the antenna structure of the present invention for achieving 3 different beam pointings, Figure 5 The actual pictures of the four antennas processed for the present invention show that the three antennas with different beam directions of the present invention are all composed of non-biased substrate integrated waveguide slot array antennas and near-field Huygens metasurfaces, and the overall profile height is 3.2 mm. Compared with antenna 4, antenna 1 does not contain a Huygens metasurface covered on the slot array antenna. The Huygens metasurface in antenna 4 is composed of a dielectric substrate and metal structures at the top and bottom of the dielectric substrate. The metal structure is composed of a pair of biased dipoles, along the long side of the rectangular slot is the y direction, along the short side of the matrix slot is the x direction, and the dipoles in the diagonal directions of the second and sixth rows in the y direction and the third and seventh rows in the x direction have smaller central angles than other dipoles. Figure 6 This is a comparison diagram of the radiation pattern of the present invention, which is simulated and measured. Figure 7 The simulation and test comparison diagrams of antenna gain with three different beam directions are given. It can be observed from these figures that when the center frequency of antenna 4 is 30 GHz, a 45° beam direction is achieved on the D plane, the cross polarization is less than -12 dB, the radiation efficiency is 63%, and the -10 dB bandwidth is 1%. The three antennas of the present invention are compared with the non-biased substrate integrated waveguide slot array antenna 1, and it is found that after the incorporation of the metasurface, the gain deviation range is 1.7 dBi to 2.6 dBi.

[0046] The above embodiments are merely illustrative of the structure, principle and efficacy of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface, characterized in that: The invention comprises a non-biased substrate integrated waveguide slot array antenna (1) and a near-field Huygens metasurface (2); the non-biased substrate integrated waveguide slot array antenna (1) comprises a first dielectric substrate (3), a metal structure (4) printed on the top and bottom of the first dielectric substrate, a slot array (5) etched on the metal structure, and a metal through hole (6) in the first dielectric substrate; the near-field Huygens metasurface comprises a second dielectric substrate (7), and metal structures (8) on the top and bottom of the second dielectric substrate.

2. The low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface according to claim 1, characterized in that: The first dielectric substrate (3) is Arlon AD250A, with a thickness of 0.762 mm.

3. The low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface according to claim 1, characterized in that: The metal structure (4) at the top and bottom of the first dielectric substrate is made of copper with a thickness of 0.035 mm.

4. According to the low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface as described in claim 1, the rectangular slot array (5) is an 8*8 rectangular slot array.

5. A Huygens metasurface loaded low-profile beam-steering millimeter-wave antenna according to claim 1 or 4, characterized in that: The rectangular slot array (5) is periodically arranged at a pitch of 5 mm at the center of the metal structure on the top of the first dielectric substrate, the size of a single slot is 3.57 mm*0.90 mm, and a plurality of metal through holes are arranged around the slot.

6. The low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface according to claim 5, characterized in that: The metal through holes (6) have a diameter of 0.4 mm and a height of 0.762 mm.

7. The Huygens metasurface loaded low-profile beam-steering millimeter-wave antenna according to claim 6, characterized in that: The direction along the long side of the rectangular slot is the y direction, and the metal through holes at a certain distance from the slot array along the negative y direction together form a 1-to-8 power divider, and the other part is distributed around the slot array.

8. The Huygens metasurface loaded low-profile beam-steering millimeter-wave antenna according to claim 1, characterized in that: The material of the second dielectric substrate (7) in the Huygens supersurface is Arlon AD250A, with a thickness of 1.524 mm.

9. The Huygens metasurface loaded low-profile beam-steering millimeter-wave antenna according to claim 1, characterized in that: The metal structures (8) at the top and bottom of the near-field Huygens are composed of a pair of biased dipoles, the material of the dipoles is copper, and the thickness is 0.035 mm.

10. The low-profile beam-steering millimeter-wave antenna loaded with a Huygens metasurface according to claim 1, characterized in that: A near-field Huygens metasurface (2) is placed 0.762 mm above the non-biased substrate integrated waveguide slot array antenna (1).

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