A broadband high-gain dual-polarized metasurface antenna

Abstract

The application belongs to the field of antenna design, and provides a broadband high-gain dual-polarized metasurface antenna to solve the problem of narrow bandwidth of traditional dual-polarized microstrip antennas. The application introduces a new pair of degenerate high-order modes in the way of increasing patches on the basis of traditional 4*4 metasurfaces, realizes the broadband characteristics by exciting three pairs of degenerate modes, reduces the electrical size of the middle patch by introducing cross slots distributed along the diagonal in the center, thereby adjusts the strongest current of the three pairs of modes to the right-angled trapezoidal patch, so that the slots placed thereunder can efficiently excite the three pairs of modes at the same time, meanwhile, introduces slots on the right-angled trapezoidal patch and the rectangular patch, uses the effect that the slots have little influence on the same direction current and great influence on the vertical current, realizes independent adjustment of the current of the two polarization modes, reduces the distribution of the opposite-phase current thereon, thereby improves the gain of the antenna, and finally realizes the broadband dual-polarized antenna with high gain.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of antenna design, and relates to a dual-polarized antenna, and particularly provides a broadband high-gain dual-polarized metasurface antenna. BACKGROUND

[0002] With the development of radars, communications and electronic countermeasures, not only is it required that the antenna is small in size, light in weight, wide in frequency band and high in gain, but also it is required that the antenna has a dual-polarized characteristic in order to meet the requirement of transceiving integration; the dual-polarized antenna can simultaneously transmit or receive two orthogonal polarized electromagnetic waves, and therefore the dual-polarized antenna can also improve the utilization rate of frequency spectrum, effectively counteract channel multipath fading, and improve the anti-interference capability of the system.

[0003] At present, commonly used dual-polarized antennas mainly include cross-dipole antennas, antennas with mixed structures and microstrip patch antennas; among them, the cross-dipole antenna usually adopts feeding two independent ports respectively to realize the polarization mode of the antenna, but the feeding part is large in volume, resulting in a high profile of the entire antenna and difficulty in design; the antenna with a mixed structure adopts different structures to produce different polarizations, but the structure asymmetry will lead to difficulty in realizing low cross-polarization; the microstrip patch antenna realizes the polarization mode by feeding different patches on the same layer of medium or feeding different patches on different layers of medium, and it usually has the advantages of low profile, small volume and simple feeding structure, but the bandwidth is generally narrow, and even if the thickness of the medium substrate is increased or a parasitic element is added to widen the bandwidth, it is difficult to meet the requirement of the modern communication system on the wide bandwidth of the antenna; with the proposal of the metasurface antenna, a new idea is provided for solving the problems existing in the microstrip antenna. SUMMARY

[0004] The application aims at the problem of narrow bandwidth of the traditional dual-polarized microstrip antenna, and provides a broadband high-gain dual-polarized metasurface antenna, which has the advantages of wide bandwidth and high gain and is simple in structure.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0006] A broadband high-gain dual-polarized metasurface antenna comprises, from top to bottom, a metasurface structure 1, a first medium substrate 2, a metal ground layer 3, a second medium substrate 4 and a microstrip feed line structure 5; wherein the metasurface structure is arranged on the upper surface of the first medium substrate, and the metal ground layer and the microstrip feed line structure are arranged on the upper surface and the lower surface of the second medium substrate, respectively.

[0007] The metasurface structure is located at the center of the upper surface of the first dielectric substrate and is symmetrical about the center line; the metasurface structure comprises: four central square patches 1-3 arranged in a 2x2 array at the center, eight right trapezoidal patches 1-1 and four edge square patches 1-4 arranged around the central square patches, and eight rectangular patches 1-2 arranged outside the right trapezoidal patches 1-1, wherein the right trapezoidal patches 1-1 are arranged outside the central square patches, and the edge square patches 1-4 are arranged at the four corners respectively.

[0008] The central square patch 1-3 is provided with a cross-shaped slot along the diagonal line, the side length of the central square patch is W, the distance between adjacent central square patches is g1, and the width of the cross-shaped slot is s1.

[0009] The lower base of the right trapezoidal patch 1-1 corresponds to the central square patch, the upper base corresponds to the rectangular patch, and the oblique waist corresponds to the edge square patch; the upper base and the lower base of the right trapezoidal patch are flush with the edges of the adjacent edge square patches; the length of the lower base of the right trapezoidal patch is W1, the length of the upper base is W2, the height is W, and W2 is six-sevenths of W1; the distance between the right trapezoidal patch 1-1 and the adjacent central square patch 1-3 is g1, the distance between the right trapezoidal patch 1-1 and the adjacent rectangular patch 1-2 is g1, the distance between the right trapezoidal patches on the same side is g, and g=g1+(W-W1); the minimum distance between the oblique waist of the right trapezoidal patch and the adjacent edge square patch is g1; a first slot is formed in the right trapezoidal patch 1-1 parallel to the oblique waist, the width of the first slot is s2, and the distance between the opening of the first slot on the upper base and the right trapezoidal waist is d, and d=0.64xW2.

[0010] The rectangular patch 1-2 is provided with a second slot along the center line in the X-axis direction, the length of the rectangular patch is W3, the width is W4, and W>W3>W1>W2, and the width of the second slot is s4.

[0011] The edge square patch 1-4 is provided with a cross-shaped slot and is divided into nine sub-patches, the edge square patch has a side length of W, and the width of the cross-shaped slot is s3.

[0012] Further, four identical rectangular coupling slots are formed in the metal floor layer 3, the four rectangular coupling slots are arranged in a square shape and are located below the right trapezoidal patch 1-1, the rectangular coupling slots are arranged parallel to the bottom edge of the right trapezoidal patch and are adjacent to the lower base.

[0013] Further, the first dielectric substrate is located directly above the second dielectric layer, and the thickness of the first dielectric substrate is greater than the thickness of the second dielectric layer.

[0014] Further, the length of the upper base of the right-angled trapezoidal patch is six-sevenths of the length of the lower base.

[0015] Further, the microstrip feed structure 5 is composed of a T-shaped microstrip feed structure 5-1 and a T-shaped microstrip feed structure 5-2; wherein the T-shaped microstrip feed structure equally divides the first signal into two equal-amplitude in-phase signals, the two signals are coupled and fed to the top-layer metasurface structure through a pair of parallel rectangular coupling slots, exciting in-phase currents of the corresponding four right-angled trapezoidal patches to produce lateral radiation; the T-shaped microstrip feed structure equally divides the second signal into two equal-amplitude in-phase signals, the two signals are coupled and fed to the top-layer metasurface structure through another pair of parallel rectangular coupling slots, exciting in-phase currents of the corresponding four right-angled trapezoidal patches to produce lateral radiation.

[0016] The principle of the application is: in order to realize the dual polarization characteristics, the uniform 4x4 metasurface structure is co-excitation by a T-shaped power division network coupled with double slot structure and a bias T-shaped power division network coupled with double slot structure, wherein the T-shaped power division network excites the x polarization field through the slot parallel to the X axis, and the bias T-shaped power division network excites the y polarization field. Four slots are respectively placed below the four middle patches on the four edges, and two mutually parallel slots are respectively excited in phase, so only the mode with in-phase strong current on the four middle patches on the four edges can be excited. Note that the excitation slot is arranged below the four middle patches on the four edges in order to better excite multiple high-order modes, thereby realizing the wideband characteristics. Here, the principle of realizing wideband high gain of the antenna is described by taking x polarization as an example, and the y polarization has similar principles, only the excitation mode in the passband has the orthogonal field distribution characteristics with the x polarization excitation mode in the passband. The uniform 4x4 metasurface structure has two lateral modes that can be excited, which are the degenerate base mode and the high-order mode 1. The base mode has weak current on the four middle patches, so it cannot be well excited; although the degenerate base mode can be excited, the current on the four middle patches, the eight patches on the upper and lower edges and the current on the two middle patches on the left and right edges are in opposite phases, and the existence of the opposite phase current causes the degenerate base mode to be canceled in the lateral direction, so that the lateral gain is low; the high-order mode 1 has opposite phase current on the four middle patches and the four corner patches and the two middle patches on the four edges, and the existence of the opposite phase current causes the high-order mode 1 to be reduced in the lateral direction; in summary, although the degenerate base mode and the high-order mode 1 are excited, the existence of the opposite phase current causes their lateral gain to be relatively low. In order to excite the base mode and improve the gain of the degenerate base mode and the high-order mode 1, the original uniform 4x4 structure is optimized into a deformed structure 1, the four middle patches are divided into a central square patch 1-3 along the diagonal cross slot, and the cross slot reduces the electrical length of the middle patch in the x direction and the y direction, so that the strongest current of the base mode moves from the middle patch to the edge patch, so that the base mode can also be excited by the slot on the edge, and the cross slot along the diagonal line makes the edge of the middle patch and the surrounding patch complete, without reducing the energy coupling with the surrounding patch. The edge patch is changed from the original square to the right trapezoidal patch 1-1, and the distance between the two adjacent right trapezoidal patches is greater than the distance between the original square patches, which is conducive to reducing the coupling of the current in this direction. The slope of the trapezoid can also weaken the energy coupling with the central square patch 1-3, thereby reducing the influence of the opposite phase current on the gain, and the slot along the slope can maintain the size of the main polarization current while reducing the current in the cross polarization direction, thereby optimizing the gain and cross polarization characteristics.The square patch on the four corners is divided into edge square patches 1-4 by the cross-shaped slot, the introduction of the slot can reduce the opposite current of the patch on the four corners, eight rectangular patches 1-2 are introduced on the outermost layer, so that a new high-order mode 2 is introduced, the bandwidth of the antenna is widened, and the slot can reduce the current in the cross-polarization direction, and the gain and cross-polarization characteristics of the antenna are optimized.

[0017] In conclusion, the application introduces a new pair of degenerate high-order modes by increasing the patch on the basis of the traditional 4*4 metasurface, and realizes the wideband characteristics by exciting three pairs of degenerate modes. By introducing the cross-shaped slot distributed along the diagonal in the center, the electrical size of the middle patch is reduced without affecting the coupling between the center patch and the surrounding patches, so that the strongest currents of the three pairs of modes are adjusted to the patch 1-1, and the slot placed thereunder can efficiently excite the three pairs of modes. By introducing the slot on the patch 1-1 and the patch 1-2, the effect of the slot on the same direction current is small, and the effect of the slot on the vertical current is large, so that the independent adjustment of the two polarized mode currents is realized, the distribution of the opposite current is reduced without affecting the working mode, and the gain of the antenna is improved. Finally, a wideband dual-polarized antenna with high gain is realized. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a schematic diagram of the metasurface structure of the wideband high-gain dual-polarized metasurface antenna in the application;

[0019] Figure 2 FIG. 2 is a schematic diagram of the side view structure of the wideband high-gain dual-polarized metasurface antenna in the application;

[0020] Figure 3 FIG. 3 is a schematic diagram of the metal ground layer structure of the wideband high-gain dual-polarized metasurface antenna in the application;

[0021] Figure 4 FIG. 4 is a schematic diagram of the microstrip feed line structure of the wideband high-gain dual-polarized metasurface antenna in the application;

[0022] Figure 5 FIG. 5 is a gain and return loss characteristic diagram of the wideband high-gain dual-polarized metasurface antenna in the embodiment of the application;

[0023] 1 is a metasurface structure, 1-1 is a right-angled trapezoidal patch, 1-2 is a rectangular patch, 1-3 is a central square patch, and 1-4 is an edge square patch; 2 is a first dielectric substrate, 3 is a metal ground layer, and 4 is a second dielectric substrate; 5 is a microstrip feed line structure, 5-1 is a T-shaped microstrip feed line structure, and 5-2 is a bias T-shaped microstrip feed line structure. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and technical effect of the present application more clear and complete, the present application will be further described in detail below with reference to the drawings and examples.

[0025] The embodiment provides a broadband high-gain dual-polarized metasurface antenna, which comprises, from top to bottom, a metasurface structure 1, a first dielectric substrate 2, a metal ground layer 3, a second dielectric substrate 4 and a microstrip feed line structure 5; wherein the first dielectric substrate 2 and the second dielectric substrate 4 are in close contact, the metasurface structure 1 is printed on the upper surface of the first dielectric substrate 2, and the metal ground layer 3 and the microstrip feed line structure 5 are printed on the upper surface and the lower surface of the second dielectric substrate 4 respectively, as shown in Figure 2 .

[0026] As shown in Figure 1 , a plane rectangular coordinate system is established with the center of the first dielectric substrate 2 as the origin, the left-right direction as the Y-axis and the up-down direction as the X-axis, and the metasurface structure is symmetrical about the X-axis and the Y-axis; the metasurface structure is composed of four different shapes of patches, including four central square patches 1-3 arranged in a 2x2 array at the center position, eight right-angled trapezoidal patches 1-1 and four edge square patches 1-4 arranged around the central square patches, and eight rectangular patches 1-2 arranged outside the right-angled trapezoidal patches 1-1, the right-angled trapezoidal patches 1-1 are arranged outside the central square patches, and the edge square patches 1-4 are arranged at the four corners respectively;

[0027] The central square patch 1-3 is provided with a cross-shaped slot along the diagonal line, the side length of the central square patch is W, the distance between adjacent central square patches is g1, and the width of the cross-shaped slot is s1;

[0028] The lower base of the right-angled trapezoidal patch 1-1 corresponds to the central square patch, the upper base corresponds to the rectangular patch, and the oblique waist corresponds to the edge square patch, and the upper base and the lower base of the right-angled trapezoidal patch are flush with the edges of the adjacent edge square patch; the length of the lower base of the right-angled trapezoidal patch is W1, the length of the upper base is W2, the height is W, and W2 is six-sevenths of W1; the distance between the right-angled trapezoidal patch 1-1 and the adjacent central square patch 1-3 is g1, the distance between the right-angled trapezoidal patch 1-1 and the adjacent rectangular patch 1-2 is g1, the distance between the right-angled trapezoidal patches on the same side is g, and g = g1 + (W-W1), the minimum distance between the oblique waist of the right-angled trapezoidal patch and the adjacent edge square patch is g1; a first slot is formed in the right-angled trapezoidal patch 1-1 parallel to the oblique waist, the width of the first slot is s2, and the opening distance of the first slot on the upper base from the right-angled waist is d, and d = 0.64*W2;

[0029] The second strip-shaped gap is arranged along the middle line of the rectangular patch 1-2 in the X-axis direction, and the rectangular patch is divided into two sub-patches, the length of the rectangular patch is W3, the width of the rectangular patch is W4, and W>W3>W1>W2, and the width of the second strip-shaped gap is s4.

[0030] The edge square patch 1-4 is provided with a cross-shaped gap and is divided into nine sub-patches, the edge length of the edge square patch is W, and the width of the cross-shaped gap is s3.

[0031] As shown in Figure 3 The metal floor layer 3 is printed on the upper surface of the second dielectric substrate 4, and four identical rectangular coupling gaps are arranged on the metal floor layer 3, wherein two rectangular coupling gaps are perpendicular to the X-axis and symmetric about the Y-axis, and the other two rectangular coupling gaps are perpendicular to the Y-axis and symmetric about the X-axis; the rectangular coupling gaps are arranged below the right-angled trapezoidal patch 1-1, and in order to make the description clearer, the right-angled trapezoidal patch 1-1 is indicated by a dashed line in Figure 3 According to the coupling feeding mechanism, when two mutually parallel coupling gaps are excited in phase, a specific mode in the top-layer metasurface structure can be excited; taking x polarization as an example, the right-angled trapezoidal patch 1-1 corresponding to the two parallel coupling gaps has a strong x-direction current, and since the designed metasurface structure has many inherent modes with this feature, the wideband radiation characteristics of the antenna are realized; and in these modes, the strongest current distribution position of some modes on the right-angled trapezoidal patch 1-1 is not in the middle part, but in the part close to the Y-axis. In order to excite these modes as much as possible and improve the gain in the working frequency band, the position of the coupling gap is arranged below the right-angled trapezoidal patch 1-1 close to the Y-axis, i.e. adjacent to the lower bottom edge.

[0032] As shown in Figure 4 The microstrip feed line structure is printed on the lower surface of the second dielectric substrate, and includes a T-shaped microstrip feed line structure 5-1 and a bias T-shaped microstrip feed line structure 5-2; the two microstrip feed line structures and the metal floor layer together constitute the microstrip slot coupling feeding structure of the antenna; the T-shaped microstrip feed line structure 5-1 and the bias T-shaped microstrip feed line structure 5-2 each include a main line and two branch signals; in order to ensure that the T-shaped microstrip feed line can feed the top-layer corresponding metasurface structure with equal amplitude and in phase, the lengths of the two branches in the T-shaped microstrip feed line structure 5-1 must be equal; in order to ensure that the bias T-shaped microstrip feed line can feed the top-layer corresponding metasurface structure with equal amplitude and in phase, the phases of the two branches in the bias T-shaped microstrip feed line structure 5-2 need to be 180° different; and the four branches are all bent to achieve better impedance matching, and the width of the bent part is different from the width of other parts.

[0033] In this embodiment,

[0034] The first dielectric substrate 2 is made of Arlon AD350A plate material with a dielectric constant of 3.5, and the thickness t1 is 4 mm; the second dielectric substrate 4 is made of Nelteg NY9260(IM) plate material with a dielectric constant of 2.6, and the thickness t2 is 0.8 mm, and the side length L is 68 mm;

[0035] The side length W of the central square patch 1-3 is 8.8 mm, the central square patch 1-3 is provided with a cross-shaped slot along the diagonal direction, the width of the cross-shaped slot is s1=0.25 mm, and the spacing g1 between adjacent central square patches 1-3 is 1 mm; the spacing between the central square patch 1-3 at the center and the right-angled trapezoidal patch 1-1 is also g1=1 mm, the lower base length of the right-angled trapezoidal patch 1-1 is W1=8.3 mm, W1 is less than W, the upper base length is W2=7 mm, W2 is six-sevenths of W1, the height is W=8.8 mm, the spacing g between adjacent right-angled trapezoidal patches 1-1 is 1.5 mm, g is greater than g1, g=g1+(W-W1), the first strip-shaped slot parallel to the diagonal waist of the right-angled trapezoidal patch 1-1 has a width s2=0.5 mm, the opening distance of the first strip-shaped slot at the upper base from the right-angled side is d=4.54 mm, d=0.64*W2; the spacing between the right-angled trapezoidal patch 1-1 and the edge square patch 1-4 is also g1=1 mm; the spacing between the right-angled trapezoidal patch 1-1 and the rectangular patch 1-2 is also g1=1 mm, the length W3 of the rectangular patch 1-2 is 8.5 mm, the width W4 is 5.5 mm, W>W3>W1>W2, the second strip-shaped slot of the rectangular patch 1-2 is provided along the middle line of the X-axis direction, and the width s4 of the second strip-shaped slot is 0.5 mm; the edge square patch 1-4 has a side length of W=8.8 mm, and is divided into nine small squares of the same size by a cross-shaped slot with a width of s3=0.5 mm; the long side width ls of the rectangular coupling slot is 18 mm, the width ws is 1.9 mm, and the distance from each rectangular coupling slot to the center is lf=14 mm.

[0036] Based on the above structural parameters, the return loss characteristic diagram and the gain diagram of the wideband high-gain dual-polarized metasurface antenna in the embodiment are as shown in Figure 5 As shown in the diagram, the return loss of the antenna in the frequency band of 5.5 GHz to 10.3 GHz is less than -10 dB, and the impedance bandwidth of the antenna can reach 60.8%; at the same time, the highest gain of the antenna can reach 11.8 dBi, and the gain in the range of 5.6 GHz to 8.9 GHz is about 10 dBi. It can be seen that the dual-polarized metasurface antenna provided by the application has good wideband high-gain characteristics.

[0037] The above merely provides the specific implementation of the present application, any feature disclosed in the specification can be replaced by other equivalent or similar purpose alternative features unless specifically described, and all features disclosed or all steps in the method or process can be combined in any manner except for mutually exclusive features and / or steps.

Claims

1. A broadband high-gain dual-polarized metasurface antenna comprising, in order from top to bottom: The super surface structure (1), the first dielectric substrate (2), the metal ground plane layer (3), the second dielectric substrate (4), and the microstrip feed line structure (5); wherein the super surface structure is arranged on the upper surface of the first dielectric substrate, the metal ground plane layer and the microstrip feed line structure are respectively arranged on the upper surface and the lower surface of the second dielectric substrate; The super surface structure is located at the center of the upper surface of the first dielectric substrate and is symmetrical about the center line; the super surface structure comprises four central square patches (1-3) arranged in a 2*2 array at the center, eight right trapezoidal patches (1-1) and four edge square patches (1-4) arranged around the central square patches, and eight rectangular patches (1-2) arranged outside the right trapezoidal patches (1-1); the right trapezoidal patches (1-1) are arranged outside the central square patches, and the edge square patches (1-4) are arranged at four corners, respectively. The central square patch (1-3) is provided with a cross-shaped slot along the diagonal line, the side length of the central square patch is W, the distance between adjacent central square patches is g1, and the width of the cross-shaped slot is s1. The lower base of the right trapezoidal patch (1-1) corresponds to the central square patch, the upper base corresponds to the rectangular patch, and the oblique waist corresponds to the edge square patch; the upper base and the lower base of the right trapezoidal patch are flush with the edges of the adjacent edge square patches; the length of the lower base of the right trapezoidal patch is W1, the length of the upper base is W2, the height is W, and W2 is six-sevenths of W1; the distance between the right trapezoidal patch (1-1) and the adjacent central square patch (1-3) is g1, the distance between the right trapezoidal patch (1-1) and the adjacent rectangular patch (1-2) is g1, the distance between the right trapezoidal patches on the same side is g, and g=g1+(W-W1); the minimum distance between the oblique waist of the right trapezoidal patch and the adjacent edge square patch is g1; a first strip-shaped slot is formed in the right trapezoidal patch (1-1) parallel to the oblique waist, the width of the first strip-shaped slot is s2, and the distance between the opening of the first strip-shaped slot on the upper base and the right trapezoidal waist is d, and d=0.64*W2; The rectangular patch (1-2) is provided with a second strip-shaped slot along the middle line in the X-axis direction; the length of the rectangular patch is W3, the width is W4, and W>W3>W1>W2; the width of the second strip-shaped slot is s4. The edge square patch (1-4) is provided with a cross-shaped slot and is divided into nine sub-patches; the side length of the edge square patch is W, and the width of the cross-shaped slot is s3.

2. The wideband high-gain dual-polarized metasurface antenna of claim 1, wherein, Four identical rectangular coupling slots are formed in the metal ground plane layer (3); the four rectangular coupling slots are arranged in a square shape and are located below the right trapezoidal patches; the rectangular coupling slots are parallel to the bottom edges of the right trapezoidal patches and are adjacent to the lower bottom edges.

3. The wideband high-gain dual-polarized metasurface antenna of claim 1, wherein, The first dielectric substrate is located directly above the second dielectric layer, and the thickness of the first dielectric substrate is greater than the thickness of the second dielectric layer.

4. The wideband high-gain dual-polarized metasurface antenna of claim 1, wherein, The length of the upper base of the right trapezoidal patch (1-1) is six-sevenths of the length of the lower base.

5. The wideband high-gain dual-polarized metasurface antenna of claim 1, wherein, The microstrip feed line structure (5) is composed of a T-shaped microstrip feed line structure (5-1) and a bias T-shaped microstrip feed line structure (5-2); wherein the T-shaped microstrip feed line structure equally divides the first signal into two equal-amplitude in-phase signals, the two signals are coupled and fed to the top-layer metasurface structure through a pair of parallel rectangular coupling slots, and in-phase currents of four right-angled trapezoidal patches at corresponding positions are excited to produce lateral radiation; the bias T-shaped microstrip feed line structure equally divides the second signal into two equal-amplitude in-phase signals, the two signals are coupled and fed to the top-layer metasurface structure through another pair of parallel rectangular coupling slots, and in-phase currents of four right-angled trapezoidal patches at corresponding positions are excited to produce lateral radiation.

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