A low-profile broadband microstrip antenna based on a metasurface

Abstract

The present invention discloses a low-profile broadband microstrip antenna based on a metasurface, comprising a metasurface radiation layer, a dielectric substrate layer and a feed layer arranged in sequence from top to bottom; the metasurface radiation layer is mounted on the upper layer of the dielectric substrate, and the feed layer is mounted on the lower layer of the dielectric substrate; the metasurface radiation layer comprises 9 circular radiation units; the feed layer comprises a CPW feed line, a triangular metal branch, a gradient coupling slot and a metal floor; the signal is input by the CPW feed line, and the signal is coupled to the metasurface radiation layer through the triangular metal branch and the gradient coupling slot, thereby forming a wider impedance bandwidth. The present invention adopts a metasurface structure with circular patches as radiation units, which not only improves the impedance bandwidth of the entire antenna, but also ensures the directivity of the high-frequency band antenna. The gradient coupling feed structure is adopted. Compared with the CPW feed line coupling feeding, the gradient structure can greatly improve the antenna impedance bandwidth and reduce the antenna profile.

Description

Technical Field

[0001] The present invention relates to the technical field of X-band antennas, and in particular to a low-profile broadband supersurface microstrip antenna. Background Art

[0002] With the rapid development of wireless communication system technology, the requirements for antenna performance are constantly increasing, and conventional antennas can no longer fully meet the requirements of modern communications. In modern communications, more communication equipment needs to be equipped in the same space, so the number of antennas needs to be increased accordingly, which makes the coupling between antennas directly affect the electrical indicators of the antennas, and ultimately affect the communication quality; therefore, an antenna is needed to meet higher transmission performance. Summary of the invention

[0003] The present invention proposes a broadband low-profile metasurface antenna, which has the characteristics of wide bandwidth, low profile, miniaturization, low cost, etc. The method is to increase the working bandwidth of the antenna, so that different communication devices can share the same antenna, thereby reducing the actual number of antennas installed; and then by reducing the size of the antenna and solving interference problems such as coupling, it can meet the requirements of modern communications.

[0004] The technical solution of the present invention is:

[0005] A low-profile broadband microstrip antenna based on a metasurface comprises a metasurface radiation layer, a dielectric substrate layer and a feeding layer which are arranged in sequence from top to bottom; the metasurface radiation layer is mounted on the upper end of the dielectric substrate layer, and the feeding layer is mounted on the lower end of the dielectric substrate layer; the metasurface radiation layer comprises 9 circular radiation units; the feeding layer comprises a CPW feed line, a triangular metal branch, a gradient coupling slot and a metal floor; a signal is input by the CPW feed line, and is coupled to the metasurface radiation layer through the triangular metal branch and the gradient coupling slot, thereby forming a wider impedance bandwidth.

[0006] As a further improvement of the above technical solution:

[0007] The nine circular radiation units are arranged in a 3x3 manner, and the radius of the circular radiation units in the middle row is larger than the radius of the circular radiation units in the upper and lower rows.

[0008] The radius of each circular radiation unit in the middle row is the same; the radius of each circular radiation unit in the upper and lower rows is the same.

[0009] One end of the CPW feeder line inputs a signal, and the other end is short-circuited with the metal floor; the end of the CPW feeder line is connected to a triangular metal branch, and the triangular metal branch is located in a gradient coupling gap.

[0010] The axis of the metasurface radiation layer coincides with the axis of the gradient coupling gap; the edge of the metal floor coincides with the edge of the dielectric substrate layer.

[0011] The beneficial effects of the present invention are:

[0012] 1. The present invention adopts a metasurface structure with circular patches as units, which not only improves the impedance bandwidth of the entire antenna, but also ensures the directivity of the high-frequency band antenna. The gradient coupling feeding structure is adopted. Compared with the CPW feed line coupling feeding, the gradient structure can greatly improve the antenna impedance bandwidth and reduce the antenna profile.

[0013] 2. Low-profile antennas have the characteristics of low profile, low wind resistance, and easy conformality with the carrier, providing a new way to realize low-profile broadband antennas; metasurfaces are based on the regular or irregular arrangement of subwavelength structures in a two-dimensional plane, which is a two-dimensional plane case of metamaterials. Due to its subwavelength and phase control characteristics, metasurfaces can realize electromagnetic wave propagation control in a very small range, which is convenient for the miniaturization design of microwave devices, stealth materials and antennas; therefore, the application of metasurfaces in low-profile broadband microstrip antennas has the technical effect of reducing the antenna's external dimensions and solving coupling interference.

[0014] 3. The low-profile broadband metasurface antenna designed by the present invention is designed for X-band wireless communication and can be widely used in UAV systems, remote sensing test systems, reconnaissance systems and carrier conformal aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the overall structure diagram;

[0016] Figure 2 It is a schematic diagram of the feeding layer structure;

[0017] Figure 3 is a schematic diagram of the radiation layer;

[0018] Figure 4 It is a schematic diagram of the cross-sectional structure;

[0019] Figure 5 It is the S11 simulation curve of the present invention, and includes the simulation S11 curves of the 3x3 square radiation metasurface and the simple monopole;

[0020] Figure 6 It is the 8GHz H-surface gain pattern of the present invention and the 3x3 square radiating metasurface;

[0021] Figure 7 It is the present invention and the 3x3 square radiating metasurface 10GHz H-surface gain pattern;

[0022] Figure 8This is the 11GHz H-surface gain pattern of the present invention and the 3x3 square radiating metasurface.

[0023] Figure numerals: 1. metasurface radiation layer; 2. dielectric substrate layer; 3. feeding layer; 4. circular radiation unit; 5. CPW feed line; 6. triangular metal branch; 7. gradient coupling gap; 8. metal floor. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be understood that the terms such as "having", "including" and "comprising" used in this document do not exclude the existence or addition of one or more other elements or combinations thereof, and the terms such as "upper", "lower", "middle", "upper end", "lower end" etc. merely distinguish the positional relationship and have no specific limitation.

[0026] The implementation of the present invention is described in detail below with reference to the accompanying drawings.

[0027] like Figure 1 As shown: A low-profile broadband microstrip antenna based on a metasurface, comprising a metasurface radiation layer 1, a dielectric substrate layer 2 and a feed layer 3 arranged in sequence from top to bottom; the metasurface radiation layer 1 is mounted on the upper end of the dielectric substrate layer 2, and the feed layer 3 is mounted on the lower end of the dielectric substrate layer 2; the metasurface radiation layer 1 includes 9 circular radiation units 4; the feed layer 3 includes a CPW feed line 5, a triangular metal branch 6, a gradient coupling slot 7 and a metal floor 8; the signal is input by the CPW feed line 5, and the signal is coupled to the metasurface radiation layer 1 through the triangular metal branch 6 and the gradient coupling slot 7, thereby forming a wider impedance bandwidth. The antenna adopts a printed circuit board process, wherein the radiation layer 1 and the feed layer 3 are made of metal copper, and the material used for the dielectric substrate layer 2 is RO4350B.

[0028] like Figure 2 As shown: a signal is input at one end of the CPW feed line 5, and the other end is short-circuited with the metal floor 8; the end of the CPW feed line 5 is connected to a triangular metal branch 6, and the triangular metal branch 6 is located in a gradient coupling slot 7. The axis of the metasurface radiation layer 1 coincides with the axis of the gradient coupling slot 7; the edge of the metal floor 8 coincides with the edge of the dielectric substrate layer 2.

[0029] Furthermore, the lower end of the CPW feeder 5 is flush with the cross section, and the upper end is connected to the metal floor 8 to form a short circuit. The upper end of the CPW feeder 5 is a triangular metal branch 6, and the triangular metal branch 6 is connected to the CPW feeder 5; the feed layer 3 is a ladder-type coupled feed structure. The width of the CPW feeder 5 is S, and the feeder extends to the center of the plane and is connected to the metal floor 8 to form a short circuit. The gap between the feeder and the metal floor 8 is g; the triangular metal branch 6 is symmetrical on the left and right, directly connected to the feeder, and its long right-angle side is L1, and the distance between it and the metal floor 8 is WF / 2; the gradient coupling gap 7 is located at the center of the entire plane, where the gradient distance is L2, symmetrical up and down, the widest width at the gradient is WF, and the narrowest width is 0.

[0030] Going further; S is 1-1.5mm; g<0.5mm; L1 is 2.5-3mm; WF is 1-1.5mm; L2 is 3.5-4mm.

[0031] like Figure 3 As shown, the 3x3 circular radiation unit 4 is composed of a regular metasurface structure, the distance between the centers of the upper and lower rows of adjacent circular radiation units 4 is a fixed value Wp+Ws, and the diameters of the upper, middle and lower columns of circular units are different, among which the diameters of the upper and lower rows of circular units are Wp, and the diameter of the middle row is Wa; the entire array is at the center of the antenna.

[0032] like Figure 4 The dielectric substrate layer 2 dimensions shown are Wg x Wg x H.

[0033] Furthermore, Wa is 5.5-6mm; Wp is 5-5.5mm; Ws is 1-1.5mm; Wg is 35-40mm; and H is 2.5-3mm.

[0034] Embodiment 1: A low-profile broadband microstrip antenna based on a metasurface, such as Figure 1 As shown; it includes a metasurface radiation layer 1, a dielectric substrate layer 2 and a feed layer 3 arranged in sequence from top to bottom; the metasurface radiation layer 1 is mounted on the upper end of the dielectric substrate layer 2, and the feed layer 3 is mounted on the lower end of the dielectric substrate layer 2; the metasurface radiation layer 1 includes 9 circular radiation units 4; the feed layer 3 includes a CPW feed line 5, a triangular metal branch 6, a gradient coupling slot 7 and a metal floor 8; the signal is input by the CPW feed line 5, and the signal is coupled to the metasurface radiation layer 1 through the triangular metal branch 6 and the gradient coupling slot 7, thereby forming a wider impedance bandwidth. The antenna adopts a printed circuit board process, in which the radiation layer 1 and the feed layer 3 are made of metal copper, and the material used for the dielectric substrate layer 2 is RO4350B. The edge of the entire dielectric substrate layer is flush with the edge of the metal floor 8 and the bottom end of the CPW feed line 5, and the axis of the metasurface radiation layer 1, the axis of the dielectric substrate layer and the axis of the second-order coupling slot coincide.

[0035] like Figure 2 As shown: the lower end of the CPW feeder 5 is flush with the cross section, and the upper end is connected to the metal floor 8 to form a short circuit. The upper end of the CPW feeder 5 is a triangular metal branch 6, which is connected to the CPW feeder 5; the feed layer 3 is a ladder-type coupled feed structure. The width S of the CPW feeder 5 is 1mm, the feeder extends to the center of the plane and is connected to the metal floor 8 to form a short circuit, and the gap g between the feeder and the metal floor 8 is 0.1mm; the triangular metal branch 6 is symmetrical on the left and right, directly connected to the feeder, and its long right-angle side length L1 is 2.5mm, and the distance WF / 2 between it and the metal floor 8 is 0.5mm; the gradient coupling gap 7 is located in the center of the entire plane, where the gradient distance L2 is 3.5mm, symmetrical up and down, the widest width at the gradient is WF, and the narrowest width is 0.

[0036] Going further; S is 1-1.5mm; g<0.5mm; L1 is 2.5-3mm; WF is 1-1.5mm; L2 is 3.5-4mm.

[0037] like Figure 3 As shown, the 3x3 circular radiation unit 4 is composed of a regular metasurface structure, the distance Wp+Ws between the centers of the upper and lower rows of adjacent circular radiation units 4 is a fixed value of 6mm, and the diameters of the upper, middle and lower columns of circular units are different, among which the diameters of the upper and lower rows of circular units are Wp, which is 5mm, and the diameter of the middle row is Wa, which is 5.5mm; the entire array is at the center of the antenna.

[0038] like Figure 4 The dimensions of the dielectric substrate layer 2 shown are Wg x Wg x H, where Wg is 35 mm and H is 2.5 mm.

[0039] Embodiment 2: The difference between this embodiment and embodiment 1 is that:

[0040] The width S of the CPW feeder line 5 is 1.5 mm. The feeder line extends to the center of the plane and is connected to the metal floor 8 to form a short circuit. The gap g between the feeder line and the metal floor 8 is 0.2 mm. The triangular metal branch 6 is symmetrical on the left and right, directly connected to the feeder line, and its long right-angle side length L1 is 3 mm. The distance WF / 2 between it and the metal floor 8 is 0.5 mm. The gradient coupling gap 7 is located in the center of the entire plane, where the gradient distance L2 is 4 mm, symmetrical up and down, the widest width at the gradient is WF, and the narrowest width is 0.

[0041] The distance between the centers of the upper and lower rows of adjacent circular radiation units 4 is a fixed value of 7mm. The diameters of the upper, middle and lower columns of circular units are different. The diameter of the upper and lower rows of circular units is Wp, which is 5.2mm, and the diameter of the middle row is Wa, which is 5.9; the entire array is at the center of the antenna; Ws is 1.2mm.

[0042] like Figure 4 The dimensions of the dielectric substrate layer 2 shown are Wg x Wg x H, where Wg is 35 mm and H is 2.5 mm.

[0043] Embodiment 3: The difference between this embodiment and embodiment 1 is that:

[0044] like Figure 2 As shown: the width S of the CPW feed line 5 is 1.2mm, the feed line extends to the center of the plane and is connected to the metal floor 8 to form a short circuit, and the gap g between the feed line and the metal floor 8 is 0.3mm; the triangular metal branch 6 is symmetrical on the left and right, directly connected to the feed line, and its long right-angle side length L1 is 2.8mm, and the distance WF / 2 between it and the metal floor 8 is 0.6; the gradient coupling gap 7 is located in the center of the entire plane, where the gradient distance L2 is 3.7mm, symmetrical up and down, the widest width at the gradient is WF, and the narrowest width is 0.

[0045] like Figure 3 As shown, the 3x3 circular radiation unit 4 is composed of a regular metasurface structure, the distance Wp+Ws between the centers of the upper and lower rows of adjacent circular radiation units 4 is a fixed value of 6.5mm, and the diameters of the upper, middle and lower columns of circular units are different. Among them, the diameter of the upper and lower rows of circular units is Wp, which is 5.2mm, and the diameter of the middle row is Wa, which is 5.8mm; the entire array is at the center of the antenna, and Ws is 1.3mm.

[0046] like Figure 4 The dimensions of the dielectric substrate layer 2 shown are Wg x Wg x H, where Wg is 38 mm and H is 2.8 mm.

[0047] Embodiment 4: This embodiment differs from Embodiment 1 in that:

[0048] The width S of the CPW feed line 5 is 1.5 mm. The feed line extends to the center of the plane and is connected to the metal floor 8 to form a short circuit. The gap g between the feed line and the metal floor 8 is 0.49 mm. The triangular metal branch 6 is symmetrical on the left and right, directly connected to the feed line, and its long right-angle side length L1 is 3 mm. The distance WF / 2 between it and the metal floor 8 is 0.75 mm. The gradient coupling gap 7 is located in the center of the entire plane, where the gradient distance L2 is 4 mm, symmetrical up and down, the widest width at the gradient is WF, and the narrowest width is 0.

[0049] The distance between the centers of the upper and lower rows of adjacent circular radiation units 4 is a fixed value of 7mm. The diameters of the upper, middle and lower columns of circular units are different. The diameter of the upper and lower rows of circular units is Wp, which is 5.5mm, and the diameter of the middle row is Wa, which is 5.5; the entire array is at the center of the antenna; Ws is 1.5mm.

[0050] like Figure 4The dimensions of the dielectric substrate layer 2 shown are Wg x Wg x H, where Wg is 35 mm and H is 2.5 mm.

[0051] Furthermore, the simulation test results of Example 2 are analyzed as follows:

[0052] Place Figure 5-8 As shown, in the antenna designed by the present invention, the designed circular regular metasurface structure is the key design to improve the antenna performance. Figure 5 It can be seen that the antenna designed by the invention can achieve S11 less than -10dB in the frequency range of 8GHz-15GHz. It completely covers the X-band frequency range, with a relative bandwidth of up to 56%, while the monopole radiation patch without a metasurface structure has a relative bandwidth of only 3% when using the same feeding structure. Therefore, the circular metasurface structure proposed in the present invention can significantly improve the bandwidth of the microstrip antenna and effectively solve the narrowband shortcomings of the microstrip antenna. The height of the entire antenna is 0.09λ0, and the size is 1.28λ0×1.28λ0, which is conducive to the conformality and compatibility of the antenna and the system, and has the characteristics of miniaturization and low cost. At the same time, the circular metasurface designed by the present invention also has a significant improvement in the antenna coefficient compared to the square metasurface. In terms of impedance bandwidth, Figure 5 It can be seen that the frequency range of the square metasurface S11 less than -10dB is 7.3GHz-12.5GHz, and the relative bandwidth is 52%. Figure 6 Figure 7 Figure 8 It can be seen that the antenna designed in the present invention still maintains good directivity at a frequency of 11 GHz without obvious grating lobes; while other structures have obvious grating lobes at a frequency of 10 GHz.

[0053] In Example 1, the high-frequency (12 GHz) radiation pattern is more stable; both fmin and fmax move toward high frequency; the high-frequency (12 GHz) gain is improved; the relative bandwidth is narrowed; and the impedance matching is worse than that of Example 2.

[0054] Example 3: The low-frequency (8 GHz) radiation pattern is improved; both fmin and fmax move toward low frequency; the low-frequency (8 GHz) gain is improved; the relative bandwidth is narrowed; and the impedance matching is worse than that of Example 2. Example 4: The low-frequency (8 GHz) radiation pattern is improved; both fmin and fmax move toward low frequency; the low-frequency (8 GHz) gain is improved; the relative bandwidth is narrowed; and the impedance matching is worse than that of Example 2.

[0055] Without limiting the scope, Example 2 serves as a preferred embodiment of the present invention.

[0056] The gradient coupled feed structure adopted in the present invention is also conducive to improving the bandwidth of the antenna. More importantly, the coupled feed structure can separate the feed line layer from the radiation layer 1, greatly reducing the influence of the feed line on the radiation characteristics. At the same time, the separation structure is conducive to the integration of the antenna with other systems, greatly facilitating the design and integration of the overall system.

[0057] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes, and can be fully applicable to various fields suitable for the present invention. For those familiar with the art, for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A low-profile broadband microstrip antenna based on a metasurface, characterized in that: The invention comprises a metasurface radiation layer (1), a dielectric substrate layer (2) and a feed layer (3) which are arranged in sequence from top to bottom; the metasurface radiation layer (1) is mounted on the upper end of the dielectric substrate layer (2), and the feed layer (3) is mounted on the lower end of the dielectric substrate layer (2); the metasurface radiation layer (1) comprises 9 circular radiation units (4); the 9 circular radiation units (4) are arranged in a 3x3 manner, and the radius of the circular radiation units (4) in the middle row is larger than the radius of the circular radiation units (4) in the two rows on both sides; The feed layer (3) comprises a CPW feed line (5), a triangular metal branch (6), a gradient coupling slot (7) and a metal floor (8); one end of the CPW feed line (5) inputs a signal, and the other end is short-circuited to the metal floor (8); the end of the CPW feed line (5) is connected to the triangular metal branch (6), and the triangular metal branch (6) is located in the gradient coupling slot (7); The signal is input from the CPW feed line (5), and is coupled to the metasurface radiation layer (1) through the triangular metal branch (6) and the gradient coupling gap (7).

2. The low-profile broadband microstrip antenna based on a metasurface according to claim 1, characterized in that: The radius of each circular radiation unit (4) in the middle row is the same; the radius of each circular radiation unit (4) in the two rows on both sides is the same.

3. The low-profile broadband microstrip antenna based on a metasurface according to claim 1 or 2, characterized in that: The axis of the metasurface radiation layer (1) coincides with the axis of the gradient coupling gap (7); The edge of the metal floor (8) coincides with the edge of the dielectric substrate layer (2).

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