Ka-band electromagnetic metasurface unit and low-profile Ka-band wave beam scanning antenna loaded with electromagnetic metasurface

Abstract

The invention discloses a Ka-band electromagnetic metasurface unit and a low-profile Ka-band wave beam scanning antenna loaded with an electromagnetic metasurface, and the Ka-band electromagnetic metasurface unit comprises an upper dielectric substrate, a middle dielectric substrate and a lower dielectric substrate which are arranged from top to bottom. Metal layers are printed on the upper surface of the upper dielectric substrate, the upper surface of the middle dielectric substrate, the upper surface of the lower dielectric substrate and the lower surface of the lower dielectric substrate, and the metal layers are the same in metal pattern, shape and size; the Ka-band wave beam scanning antenna comprises an upper-layer Ka-band electromagnetic metasurface, a lower-layer Ka-band electromagnetic metasurface and a microstrip antenna feed source which are arranged from top to bottom; the micro-strip antenna is used as a feed source, and the two layers of metasurfaces are rotated, so that beam scanning of a pitching surface can be carried out in a frequency band of 30.5 GHz to 32.5 GHz, and a maximum scanning effect of + / -56 degrees is realized; the antenna has the advantages of low junction profile, low loss, low cost, high gain and easiness in manufacturing.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology, and specifically relates to a Ka-band electromagnetic metasurface unit and a low-profile Ka-band beam scanning antenna loaded with an electromagnetic metasurface. The present invention can be used for millimeter wave antenna communication and high-resolution radar imaging. Background Art

[0002] With the rapid development of wireless communication technology, broadband, miniaturization, multi-channel communication and multi-system collaboration of wireless communication equipment have become the development trend.

[0003] Beam scanning antennas can be divided into traditional low-complexity mechanical scanning antennas and phased array antennas. Phased array antennas are antenna arrays composed of multiple independent identical or different antenna units in a certain arrangement. The radiation pattern of the array is adjusted by accurately changing the phase shift of each antenna unit with the help of back-end devices. Phased arrays can quickly and accurately direct wireless signals and have strong target processing capabilities. They have been widely used in satellite communications, radar systems, medical imaging and other fields. However, phased array systems require a large number of phase shifters and transceiver modules. The heat dissipation problem of phase shifters or transceiver modules under high power conditions also increases the difficulty of design. It is very complex and costly, so it is necessary to develop low-complexity and low-cost beam scanning antennas.

[0004] Compared with phased array antennas, mechanical scanning antennas do not control the direction of the beam through the electronic phase shift used by the phased array, but achieve beam steering by loading a beam steering electromagnetic metasurface on the feed antenna to change the phase of the electromagnetic wave, and achieve beam scanning through the mutual rotation of the double-layer electromagnetic metasurface. The advantage of this design is that it has low loss and greatly reduces costs, but its most significant disadvantage is that it reduces the scanning speed. Therefore, in high-power processing, low-cost and low-complexity, non-high-speed beam scanning scenarios, mechanical scanning antennas based on electromagnetic metamaterial coatings can provide a good alternative.

[0005] In 2023, Xidian University disclosed a low-profile Ka-band metasurface unit in the patent document "Ka-band metasurface unit based on low profile and beam scanning antenna loaded thereon" (application number 202310202469.2, application publication number CN 116031658 A), including an upper dielectric substrate and a lower dielectric substrate, the upper surface of the upper dielectric substrate, the lower surface of the lower dielectric substrate, and the lower surface of the upper dielectric substrate or the upper surface of the lower dielectric substrate are all printed with the same metal pattern and the metal layer with relative projections. By using different metasurface units at different positions for phase compensation, beam deflection is achieved, and the main beam is scanned on the pitch plane by changing the relative rotation angle between the two metasurfaces. However, due to the use of a horn antenna as a feed source, this technology has the disadvantage of an overall profile that is too high.

[0006] In 2024, Xidian University disclosed a phase-independently controlled low-sidelobe high-gain metalens antenna and its preparation method in the patent document "A phase-independently controlled low-sidelobe high-gain metalens antenna and its preparation method" (application number 202411346960.3, application publication number CN 119029560A). The antenna consists of m×m single-layer transmission-type polarization conversion unit structures. By using a single-layer polarization conversion metasurface, only a polarization unit structure with a phase range of 180° needs to be designed, and the number of optimized units required is smaller; it is easy to implement, low cost, and can integrate and miniaturize devices, which is conducive to mass production and application. However, since only one layer of metasurface is used, the beam can only be focused in one direction, and beam scanning cannot be achieved. Summary of the invention

[0007] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a Ka-band electromagnetic metasurface unit and a low-profile Ka-band beam scanning antenna loaded with an electromagnetic metasurface. The present invention is based on electromagnetic metamaterials and utilizes a mechanically rotating double-layer metasurface to achieve beam scanning in the pitch plane. It can achieve a maximum scanning effect of ±56° in the frequency band of 30.5 to 32.5 GHz, without designing a complex feeding network and power division structure. It has the advantages of low profile, low loss, low cost, high gain, simple structure and easy implementation.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A Ka-band electromagnetic metasurface unit comprises an upper dielectric substrate 2, a middle dielectric substrate 3 and a lower dielectric substrate 4 arranged from top to bottom, wherein metal layers 1 are printed on the upper surface of the upper dielectric substrate 2, the upper surface of the middle dielectric substrate 3, the upper surface of the lower dielectric substrate 4 and the lower surface of the lower dielectric substrate 4 respectively, wherein metal through holes 5 are connected through the metal layers 1, and metal patterns of the same shape and size are printed on the metal layers 1; and the metal layers 1 present a centrally symmetrical structure.

[0010] The metal pattern printed on the metal layer 1 includes a square patch 101 located at the center of the metal layer 1 , a first square ring metal line 103 and a second square ring metal strip line 102 at the edge of the metal layer 1 , and the second square ring metal strip line 102 is located between the first square ring metal line 103 and the square patch 101 .

[0011] The side length of the square patch (101) is w, and the value of w is 0.5-2.68 mm.

[0012] The sizes of the square patches (101) of the metal layer (1) of the unit are different, so the phases are different. When the w value is within the range of 0.5-2.68 mm, the w value is customized to obtain a variety of Ka-band electromagnetic metasurface units, each of which covers 60°, thereby achieving uniform coverage of the entire 360° phase space.

[0013] The w value is customized within the range of 0.5-2.68 mm to obtain a variety of Ka-band electromagnetic metasurface units, each metasurface unit covers 60°, and achieves uniform coverage of the entire 360° phase space, specifically:

[0014] The first Ka-band electromagnetic metasurface unit, w = 2.68 mm, covers the 0° to 60° phase space;

[0015] The second Ka-band electromagnetic metasurface unit, w = 2.53 mm, covers the phase space from 60° to 120°;

[0016] The third Ka-band electromagnetic metasurface unit, w = 2.30 mm, covers the 120° to 180° phase space;

[0017] The fourth Ka-band electromagnetic metasurface unit, w = 2.00 mm, covers the 180° to 240° phase space;

[0018] The fifth Ka-band electromagnetic metasurface unit, w = 1.3 mm, covers the 240° to 300° phase space;

[0019] The sixth Ka-band electromagnetic metasurface unit, w = 0.5 mm, covers 300° to 360° phase space.

[0020] A low-profile Ka-band beam scanning antenna loaded with a Ka-band electromagnetic metasurface comprises an upper Ka-band electromagnetic metasurface 6, a lower Ka-band electromagnetic metasurface 7 and a microstrip antenna feed 8 arranged from top to bottom, wherein the geometric centers of the upper Ka-band electromagnetic metasurface 6, the lower Ka-band electromagnetic metasurface 7 and the microstrip antenna feed 8 are all on the same coordinate axis z; by rotating and changing the angle δ1 between the upper Ka-band electromagnetic metasurface 6 and the central coordinate axis, and the angle δ2 between the lower Ka-band electromagnetic metasurface 7 and the central coordinate axis, beam scanning of the antenna in a pitch plane is achieved.

[0021] The upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface 7 are both arranged with M*N array-distributed Ka-band electromagnetic metasurface units; different Ka-band metasurface units are used at different positions of the lower Ka-band electromagnetic metasurface 7 to perform phase compensation for spatial phase delay to achieve beam deflection; wherein, M≥2, N≥2.

[0022] The specific method of realizing beam scanning of the antenna in the elevation plane by rotating and changing the angle δ1 between the upper Ka-band electromagnetic metasurface 6 and the central coordinate axis, and the angle δ2 between the lower Ka-band electromagnetic metasurface 7 and the central coordinate axis is as follows:

[0023] ψ1 and ψ2 represent the azimuth planes where the linear phase drop directions of the upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface 7 are located, wherein ψ1 and ψ2 are within the interval [-180°, 180°]. First, the initial azimuth angles of the upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface (7) are The upper Ka-band electromagnetic supersurface 6 and the lower Ka-band electromagnetic supersurface 7 are rotated in opposite directions along the central axis perpendicular to the two supersurfaces, so that When α1=α2, α1 is the angle between the upper Ka-band electromagnetic metasurface 6 and the central axis, and α2 is the angle between the lower Ka-band electromagnetic metasurface 7 and the central coordinate axis. The beam pitch angle θ and azimuth angle can be obtained by calculation.

[0024]

[0025] The specific method for achieving beam deflection is:

[0026] 1) The electromagnetic wave radiated by the microstrip antenna feed source 8 is similar to a spherical wave, and the distances to the lower surfaces of each unit of the lower Ka-band electromagnetic metasurface 7 are different, resulting in spatial phase delay. Based on this, different Ka-band metasurface units are used at different positions of the lower Ka-band electromagnetic metasurface 7 to compensate for the spatial phase delay; in order to change the electromagnetic wave radiated by the microstrip antenna feed source 8 into a high-gain beam in a specified direction, the spatial phase delay to be compensated is:

[0027]

[0028] Where k0 is the free space wave number, and the position coordinates of the (i, j)th metasurface unit are (x (i,j) ,y (i,j) ), z is the distance between the phase center of the microstrip antenna feed 8 and the lower surface of the lower Ka-band electromagnetic metasurface 7;

[0029] 2) After compensating for the spatial phase delay, a high-gain beam perpendicular to the underlying Ka-band electromagnetic metasurface 7 is generated, further changing the focusing direction of the main beam An additional gradient phase is introduced on the lower Ka-band electromagnetic metasurface 7, and the mathematical expression of the introduced gradient phase is:

[0030]

[0031] The sum of the spatial phase delay and the gradient phase is the transmission phase of each metasurface unit on the lower Ka-band electromagnetic metasurface 7 The mathematical expression is:

[0032]

[0033] Among them, φ0 is the reference phase, which means that the phase shift distribution of the entire aperture is a relative value rather than an absolute value;

[0034] 3) The distance that the electromagnetic wave reaches the upper Ka-band electromagnetic metasurface 6 after passing through the lower Ka-band metasurface 7 is the same, so the upper Ka-band electromagnetic metasurface 6 only needs to change the main beam focusing direction A gradient phase is introduced into the upper Ka-band electromagnetic metasurface 6, and the specific mathematical expression is:

[0035]

[0036] The operating frequency band of the beam scanning antenna covers 30.5 to 32.5 GHz.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. The present invention utilizes two layers of rotating electromagnetic metasurfaces to achieve beam scanning in azimuth and elevation planes at 30.5 GHz to 32.5 GHz, and can achieve a maximum scanning effect of ±56° in the elevation plane. Compared with traditional phased arrays, the antenna can eliminate complex phase shifters and transceiver components, and does not require the design of complex feeding phase shift networks. Only one feed antenna is needed to obtain a high-gain, highly directional beam. It has the advantages of low profile, low loss, low cost, high gain and easy manufacturing. It has a relatively simple structure and is easy to implement in engineering, and is more suitable for high-power, non-high-speed beam scanning application scenarios.

[0039] 2. The metal patches of the metasurface units in the present invention are connected through metallized vias located at the geometric center of the dielectric substrate. The metal vias can improve the transmission phase of the unit. By changing the size of the metal patches, the precise division of the gradient phase can be achieved, and the phase of the electromagnetic wave can be efficiently controlled. The traditional Risley prism antenna is relatively heavy and bulky, and is not easy to integrate. The metasurface composed of metasurface units has the characteristics of low profile, small size, easy operation and integration while achieving the same function as the Risley prism.

[0040] In summary, the present invention uses a rotating double-layer electromagnetic metasurface to achieve beam scanning in the pitch plane at 30.5 GHz to 32.5 GHz, and can achieve a maximum scanning effect of ±56° within the frequency band. Compared with the active phased array, the present invention has the advantages of low profile, low loss, low cost, high gain and easy manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a structural diagram of the Ka-band electromagnetic supersurface unit of the present invention.

[0042] Figure 2 It is a side view of the Ka-band electromagnetic supersurface unit structure of the present invention.

[0043] Figure 3 It is a front view of the Ka-band electromagnetic supersurface unit structure of the present invention.

[0044] Figure 4 This is a front view of the Ka-band electromagnetic supersurface unit structure with 6 different phases of the present invention.

[0045] Figure 5 It is the transmission amplitude of 6 Ka-band electromagnetic metasurface units with different phases in the frequency band of the present invention.

[0046] Figure 6 It is the transmission phase of the six Ka-band electromagnetic metasurface units with different phases in the frequency band of the present invention.

[0047] Figure 7 This is a structural diagram of the lower Ka-band electromagnetic supersurface of the present invention.

[0048] Figure 8 This is a structural diagram of the upper Ka-band electromagnetic supersurface of the present invention.

[0049] Fig. 9 This is the overall structure diagram of the beam scanning antenna of the present invention.

[0050] Fig.10 This is the radiation pattern of phi=0° when the two layers of the supersurface of the beam scanning antenna of the present invention are relatively rotated 180°.

[0051] Fig.11 This is the radiation pattern of phi=0° when the two layers of the supersurface of the beam scanning antenna of the present invention are relatively rotated 90°.

[0052] Fig.12 This is the radiation pattern of phi=0° when the two layers of the supersurface of the beam scanning antenna of the present invention are relatively rotated by 60°.

[0053] Fig.13 It is the radiation pattern of phi=0° when the two layers of supersurfaces of the beam scanning antenna of the present invention are relatively rotated by 0°. DETAILED DESCRIPTION

[0054] The embodiments and effects of the present invention are further described below in conjunction with the accompanying drawings.

[0055] Reference Figure 1 , Figure 2 and Figure 3 A Ka-band electromagnetic metasurface unit comprises an upper dielectric substrate 2, a middle dielectric substrate 3 and a lower dielectric substrate 4 arranged from top to bottom, and four metal layers 1 printed on the upper surface of the upper dielectric substrate, the upper surface of the middle dielectric substrate, the upper surface of the lower dielectric substrate and the lower surface of the lower dielectric substrate, wherein the metal patterns of the metal layers 1 are the same in shape and size, and metal through holes 5 are connected through the metal layers 1;

[0056] The metal layer 1 includes a square patch 101, a square ring metal strip line 102 and a square ring metal strip line 103 from the inside to the outside, wherein the square patch 101 is located at the center of the unit, and the square ring metal strip line 102 and the square ring metal strip line 103 are located at the edge of the unit;

[0057] Reference Figure 4 A Ka-band electromagnetic metasurface unit adopts a central symmetric structure and is insensitive to polarization. The sizes of the square patches 101 of each metal layer 1 are different, and the phases are different. The side lengths of the square patches 101 are selected as follows to obtain 6 types of Ka-band electromagnetic metasurface units, which can basically cover the full phase space from 0° to 360°:

[0058] The first Ka-band electromagnetic metasurface unit, w = 2.68 mm;

[0059] The second Ka-band electromagnetic metasurface unit, w = 2.53 mm;

[0060] The third type of Ka-band electromagnetic metasurface unit, w = 2.30 mm;

[0061] The fourth Ka-band electromagnetic metasurface unit, w = 2.00 mm;

[0062] The fifth Ka-band electromagnetic metasurface unit, w = 1.3 mm;

[0063] The sixth type of Ka-band electromagnetic metasurface unit, w = 0.5 mm;

[0064] Reference Figure 7 and Figure 8 The upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface 7 are both arranged with M*N array-distributed Ka-band electromagnetic metasurface units, and different Ka-band metasurface units are used for different positions to compensate for the spatial phase of the electromagnetic wave to achieve beam deflection; wherein, M≥2, N≥2.

[0065] Reference Fig. 9A low-profile Ka-band beam scanning antenna based on electromagnetic metasurface loading, comprising an upper Ka-band electromagnetic metasurface 6, a lower Ka-band electromagnetic metasurface 7 and a microstrip antenna feed 8 arranged from top to bottom, wherein the geometric centers of the upper Ka-band electromagnetic metasurface 6, the lower Ka-band electromagnetic metasurface 7 and the microstrip antenna feed 8 are all on the same coordinate axis z; by rotating and changing the angle α1 between the upper Ka-band electromagnetic metasurface 6 and the central coordinate axis, and the angle α2 between the lower Ka-band electromagnetic metasurface 7 and the central coordinate axis, the beam scanning of the antenna in the pitch plane is realized.

[0066] The electromagnetic wave radiated by the microstrip antenna feed 8 is similar to a plane wave, and the distances to the lower surface of each unit of the lower Ka-band electromagnetic metasurface 7 are different, thereby generating a spatial phase delay. In order to change the electromagnetic wave radiated by the feed into a high-gain beam in a specified direction, different units need to be used at different positions for phase compensation, and the required spatial phase delay is:

[0067]

[0068] Where k0 is the free space wave number, and the position coordinates of the (i, j)th metasurface unit are (x (i,j) ,y (i,j) ), z is the distance between the phase center of the feed source and the lower surface of the lower Ka-band electromagnetic metasurface 7;

[0069] After compensating for the spatial phase delay, the lower Ka-band electromagnetic metasurface 7 can generate a high-gain beam perpendicular to the aperture surface. If it is necessary to further change the focusing direction of the main beam It is necessary to introduce an additional gradient phase on the lower Ka-band electromagnetic metasurface 7. The mathematical expression of the gradient phase required for each Ka-band metasurface unit is:

[0070]

[0071] The sum of the spatial phase delay and the gradient phase is the transmission phase of each metasurface unit on the lower Ka-band electromagnetic metasurface 7 The mathematical expression is:

[0072]

[0073] Among them, φ0 is the reference phase, which means that the phase shift distribution of the entire aperture is a relative value rather than an absolute value.

[0074] The transmission phase of each metasurface unit of the upper Ka-band electromagnetic metasurface 6 is The electromagnetic waves are in phase after being transmitted by the lower Ka-band electromagnetic metasurface 7, so the upper Ka-band electromagnetic metasurface 6 only needs to change the main beam focusing direction. The specific mathematical expression is:

[0075]

[0076] By coaxially rotating the upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface 7 in opposite directions, the main beam is scanned in a 3-D conical space; ψ1 and ψ2 represent the azimuth planes where the linear phase decrease directions of the upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface 7 are located, where ψ1 and ψ2 are in the interval [-180°, 180°]; specifically:

[0077] First, the initial azimuth angles of the upper Ka-band electromagnetic supersurface 6 and the lower Ka-band electromagnetic supersurface 7 are set to The upper Ka-band electromagnetic supersurface 6 and the lower Ka-band electromagnetic supersurface 7 are rotated in opposite directions along an axis perpendicular to the two supersurfaces, so that Where δ1 and δ2 are the rotation angles of the upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface 7. When α1 = α2, the beam pitch angle θ and azimuth angle can be obtained by calculation.

[0078] The operating frequency band of the beam scanning antenna covers 30.5 to 32.5 GHz. At 31.5 GHz, by rotating the upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface 7, when δ=δ1+δ2=0°, a maximum scanning angle of 56° can be achieved in the pitch plane; when δ=δ1+δ2=180°, the scanning angle is 0° and the maximum gain is 20.14 dB.

[0079] Combination Figure 1 and Figure 2 As shown, in this embodiment, the heights of the upper dielectric substrate 2, the middle dielectric substrate 3 and the lower dielectric substrate 4 are all h=0.8 mm, the radius of the metal through hole 5 is r=0.2 mm, the models of the upper, middle and lower dielectric substrates are all TX220F, the relative dielectric constant is 2.2, the loss tangent is 0.001, the overall cross-sectional height of the metasurface unit is 2.4 mm, and the plane size is 4×4 mm.

[0080] Combination Figure 3 As shown, in this embodiment, the width w1 of the square ring-shaped metal strip line 102 in the metal layer 1 is 0.1 mm, and the width w2 of the square ring-shaped metal strip line 103 is 0.1 mm.

[0081] Combination Fig. 9As shown, in this embodiment, the beam scanning antenna, the upper Ka-band electromagnetic supersurface 6 is composed of 20×20 Ka-band electromagnetic supersurface units, and the units at the four corners are removed, and the lower Ka-band electromagnetic supersurface 7 is composed of 20×20 Ka-band electromagnetic supersurface units, and the units at the four corners are removed.

[0082] The effect of the present invention is further described below in conjunction with simulation experiments.

[0083] Simulation experiment conditions

[0084] The simulation experiment of the present invention uses the Ansys Electronics Desktop software platform installed on computer hardware to complete the simulation of the Ka-band electromagnetic metasurface unit and the beam scanning antenna.

[0085] Simulation content and result analysis

[0086] Simulation 1: The transmission coefficient of the metasurface unit of the embodiment of the present invention is simulated and calculated in the range of 30.5 to 32.5 GHz. The results are as follows: Figure 5 and Figure 6 shown.

[0087] Figure 5 Shown is the transmission amplitude result diagram of 6 different Ka-band electromagnetic metasurface units. It can be seen from the figure that the transmission amplitude in the 30.5-32.5 GHz frequency band is above -2 dB, which has a relatively high transmission amplitude.

[0088] Figure 6 The figure shows the transmission phase results of 6 different Ka-band electromagnetic metasurface units. It can be seen from the figure that the transmission phase in the 31.5 GHz frequency band satisfies the 60° phase difference, and can approximately achieve a 60° phase difference in the 30.5-32.5 GHz frequency band.

[0089] Simulation 2: The beam scanning antenna of the embodiment of the present invention is simulated at 30.5-32.5 GHz, where the relative rotation angle between the two layers of Ka-band electromagnetic metasurface is 180°. The results are as follows: Fig.10 shown.

[0090] Fig.10 The figure shows the radiation pattern of the beam scanning antenna in this embodiment in the phi=0° plane. It can be seen from the figure that the maximum gain points to 0° at 31.5 GHz, which is consistent with the theoretical calculation, and the maximum gain is 21.14 dB.

[0091] Simulation 3: The beam scanning antenna of the embodiment of the present invention is simulated at 30.5-32.5 GHz, where the relative rotation angle between the two layers of Ka-band electromagnetic metasurface is 90°. The results are as follows: Fig.11 shown.

[0092] Fig.11 The figure shows the radiation pattern of the beam scanning antenna in this embodiment in the phi=0° plane. It can be seen from the figure that the maximum gain points to 35° at 31.5 GHz, which is consistent with the theoretical calculation, and the maximum gain is 19.80 dB.

[0093] Simulation 4: The beam scanning antenna of the embodiment of the present invention is simulated at 30.5-32.5 GHz, where the relative rotation angle between the two layers of Ka-band electromagnetic metasurface is 60°. The results are as follows: Fig.12 shown.

[0094] Fig.12 The figure shows the radiation pattern of the beam scanning antenna in this embodiment in the phi=0° plane. It can be seen from the figure that the maximum gain points to 43° at 31.5 GHz, which is consistent with the theoretical calculation, and the maximum gain is 18.46 dB.

[0095] Simulation 5: The beam scanning antenna of the embodiment of the present invention is simulated at 30.5-32.5 GHz, where the relative rotation angle between the two layers of Ka-band electromagnetic metasurface is 0°. The results are as follows: Fig.13 shown.

[0096] Fig.13 The figure shows the radiation pattern of the beam scanning antenna in this embodiment in the phi=0° plane. It can be seen from the figure that the maximum gain points to 56° at 31.5 GHz, which is consistent with the theoretical calculation, and the maximum gain is 18.28 dB.

[0097] The metasurface unit in the simulation example 1 has good gradient phase characteristics, and has a good transmission coefficient in the required frequency band of 30.5 to 32.5 GHz, making it suitable as a gradient phase metasurface unit. It can be seen from the simulation example 1 that, compared with the prior art, the metasurface unit of the present invention changes smoothly at different frequency points.

[0098] In simulation 2, simulation 3, simulation 4 and simulation 5, within the working frequency band of 30.5 to 32.5 GHz, the beam scanning antenna can achieve accurate beam scanning by rotating the upper Ka-band electromagnetic metasurface 6 and the lower Ka-band electromagnetic metasurface 7, and can achieve ±56° scanning within the frequency band, with good scanning effect. It can be seen from the above simulation embodiments that, compared with the prior art, the beam scanning range that can be achieved by the present invention is larger, and the gain loss is low.

[0099] The specific embodiments of the present invention do not constitute any limitation to the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, they may make various modifications and changes in form and details without departing from the principles and structures of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A Ka-band electromagnetic metasurface unit, comprising an upper dielectric substrate (2), a middle dielectric substrate (3) and a lower dielectric substrate (4) arranged from top to bottom, wherein the upper surface of the upper dielectric substrate (2), the upper surface of the middle dielectric substrate (3), the upper surface of the lower dielectric substrate (4) and the lower surface of the lower dielectric substrate (4) are respectively printed with a metal layer (1), characterized in that: Metal through holes (5) are connected through the metal layers (1), and metal patterns of the same shape and size are printed on the metal layers (1); the metal layers (1) present a centrally symmetrical structure.

2. A Ka-band electromagnetic metasurface unit according to claim 1, characterized in that: The metal pattern printed on the metal layer (1) comprises a square patch (101) located at the center of the metal layer (1), a first square ring-shaped metal line (103) and a second square ring-shaped metal strip line (102) at the edge of the metal layer (1), and the second square ring-shaped metal strip line (102) is located between the first square ring-shaped metal line (103) and the square patch (101).

3. The Ka-band electromagnetic metasurface unit according to claim 2, characterized in that: The side length of the square patch (101) is w, and the value of w is 0.5-2.68 mm.

4. A Ka-band electromagnetic metasurface unit according to claim 2 or 3, characterized in that: The square patch (101) has different sizes, resulting in different phases. When the w value is within the range of 0.5-2.68 mm, a customized w value is set to obtain a variety of Ka-band electromagnetic metasurface units, each of which covers 60°, thereby achieving uniform coverage of the entire 360° phase space.

5. A Ka-band electromagnetic metasurface unit according to claim 4, characterized in that: The w value is customized within the range of 0.5-2.68 mm to obtain a variety of Ka-band electromagnetic metasurface units, each metasurface unit covers 60°, and achieves uniform coverage of the entire 360° phase space, specifically: The first Ka-band electromagnetic metasurface unit, w = 2.68 mm, covers the 0° to 60° phase space; The second Ka-band electromagnetic metasurface unit, w = 2.53 mm, covers the 60° to 120° phase space; The third type of Ka-band electromagnetic metasurface unit, w = 2.30 mm, covers the 120° to 180° phase space; The fourth Ka-band electromagnetic metasurface unit, w = 2.00 mm, covers the 180° to 240° phase space; The fifth Ka-band electromagnetic metasurface unit, w = 1.3 mm, covers the 240° to 300° phase space; The sixth Ka-band electromagnetic metasurface unit, w = 0.5 mm, covers 300° to 360° phase space.

6. A low-profile Ka-band beam scanning antenna loaded with a Ka-band electromagnetic metasurface, characterized in that: The invention comprises an upper Ka-band electromagnetic supersurface (6), a lower Ka-band electromagnetic supersurface (7) and a microstrip antenna feed (8) which are arranged from top to bottom, wherein the geometric centers of the upper Ka-band electromagnetic supersurface (6), the lower Ka-band electromagnetic supersurface (7) and the microstrip antenna feed (8) are all located on the same coordinate axis z; by rotating and changing the angle δ1 between the upper Ka-band electromagnetic supersurface (6) and the central coordinate axis, and the angle δ2 between the lower Ka-band electromagnetic supersurface (7) and the central coordinate axis, beam scanning of the antenna in the pitch plane is achieved.

7. The low-profile Ka-band beam scanning antenna loaded with a Ka-band electromagnetic metasurface according to claim 6, characterized in that: The upper Ka-band electromagnetic supersurface (6) and the lower Ka-band electromagnetic supersurface (7) are both arranged with M*N array-distributed Ka-band electromagnetic supersurface units; different Ka-band supersurface units are used at different positions of the lower Ka-band electromagnetic supersurface (7) to perform phase compensation on spatial phase delay, so as to achieve beam deflection; wherein M≥2, N≥2.

8. The low-profile Ka-band beam scanning antenna loaded with a Ka-band electromagnetic metasurface according to claim 6, characterized in that: The specific method of realizing beam scanning of the antenna in the elevation plane by rotating and changing the angle δ1 between the upper Ka-band electromagnetic metasurface (6) and the central coordinate axis, and the angle δ2 between the lower Ka-band electromagnetic metasurface (7) and the central coordinate axis is as follows: ψ1 and ψ2 represent the azimuth planes where the linear phase drop directions of the upper Ka-band electromagnetic metasurface (6) and the lower Ka-band electromagnetic metasurface (7) are located, wherein ψ1 and ψ2 are within the interval [-180°, 180°]. First, the initial azimuth angles of the upper Ka-band electromagnetic metasurface (6) and the lower Ka-band electromagnetic metasurface (7) are The upper Ka-band electromagnetic metasurface (6) and the lower Ka-band electromagnetic metasurface (7) are rotated in opposite directions along the central axis perpendicular to the two metasurfaces, so that When α1=α2, α1 is the angle between the upper Ka-band electromagnetic metasurface (6) and the central axis, and α2 is the angle between the lower Ka-band electromagnetic metasurface (7) and the central coordinate axis. The beam pitch angle θ and azimuth angle can be obtained by calculation.

9. The low-profile Ka-band beam scanning antenna loaded with a Ka-band electromagnetic metasurface according to claim 7, characterized in that: The specific method for achieving beam deflection is: 1) The electromagnetic wave radiated by the microstrip antenna feed source (8) is similar to a spherical wave, and reaches different distances from the lower surface of each unit of the lower Ka-band electromagnetic metasurface (7), thereby generating a spatial phase delay. Based on this, different Ka-band metasurface units are used at different positions of the lower Ka-band electromagnetic metasurface (7) to perform phase compensation for the spatial phase delay; so as to change the electromagnetic wave radiated by the microstrip antenna feed source (8) into a high-gain beam in a specified direction, and the spatial phase delay to be compensated is: Where k0 is the free space wave number, and the position coordinates of the (i, j)th metasurface unit are (x (i,j) ,y (i,j) ), z is the distance between the phase center of the microstrip antenna feed (8) and the lower surface of the underlying Ka-band electromagnetic metasurface (7); 2) After compensating for the spatial phase delay, a high-gain beam is generated perpendicular to the underlying Ka-band electromagnetic metasurface (7), further changing the focusing direction of the main beam An additional gradient phase is introduced on the lower Ka-band electromagnetic metasurface (7), and the mathematical expression of the introduced gradient phase is: The sum of the spatial phase delay and the gradient phase is the transmission phase of each metasurface unit on the lower Ka-band electromagnetic metasurface (7) The mathematical expression is: Among them, φ0 is the reference phase, which means that the phase shift distribution of the entire aperture is a relative value rather than an absolute value; 3) The distance that the electromagnetic wave reaches from the lower Ka-band metasurface (7) to the upper Ka-band electromagnetic metasurface (6) is the same, so the upper Ka-band electromagnetic metasurface (6) only needs to change the main beam focusing direction. A gradient phase is introduced into the upper Ka-band electromagnetic metasurface (6), and the specific mathematical expression is:

10. The low-profile Ka-band beam scanning antenna loaded with a Ka-band electromagnetic metasurface according to any one of claims 6 to 9, characterized in that: The operating frequency band of the beam scanning antenna covers 30.5 to 32.5 GHz.

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