Broadband miniaturized metasurface antenna based on double-layer planar spiral structure

Abstract

The invention discloses a broadband miniaturized metasurface antenna based on a double-layer planar spiral structure, which comprises a multi-layer stacked structure and specifically comprises four layers of metal structures and three layers of dielectric substrate structures, the four layers of metal structures are respectively a first metasurface layer, a second metasurface layer, a metal ground layer with a coupling gap and a micro-strip feeder line layer; the three layers of dielectric substrates are respectively an upper layer dielectric substrate, a middle layer dielectric substrate and a lower layer dielectric substrate, the dielectric substrates are arranged from top to bottom, and the four layers of metal structures are respectively attached to the surfaces of the corresponding dielectric substrates; a penetrating metal through hole is formed in the upper dielectric substrate and is used for realizing electrical interconnection between the first super-surface layer and the second super-surface layer; the first metasurface layer and the second metasurface layer are both composed of a plurality of nested planar spiral metal patches which are periodically arranged. The overall size of the metasurface antenna can be remarkably reduced, and meanwhile broadband work, high gain and stable edge emission radiation performance are achieved.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, and in particular relates to a broadband miniaturized metasurface antenna based on a double-layer planar spiral structure. Background Technology

[0002] With the rapid development of modern wireless communication technology, wireless communication systems have placed multi-dimensional demands on antenna performance, requiring antennas to simultaneously possess characteristics such as wide operating bandwidth, miniaturized structure, ease of system integration, and low cost. Microstrip patch antennas, with their advantages of low profile, low cost, ease of engineering and manufacturing, and good system integration, have been widely used in various wireless systems such as wireless communication, satellite communication, and radar detection. However, traditional microstrip patch antennas suffer from narrow operating bandwidth and low radiation gain, making it difficult to meet the ever-increasing demands of modern communication systems for high data capacity and high transmission rates.

[0003] In recent years, metasurface antennas based on periodic metasurface structures have utilized the nonlinear dispersion characteristics of metasurfaces to simultaneously excite multiple adjacent resonant modes, thereby achieving wide impedance bandwidth and high gain. For example, in existing technologies, aperture-coupled fed metasurface antennas can achieve an impedance bandwidth of 28%, but the overall structural size of such antennas is relatively large, facing many limitations in system integration and array design applications. Currently, the industry often uses methods such as double / multi-layer metasurface structures, adjusting the gaps between metasurface units, and loading equivalent capacitance structures to reduce antenna size. However, existing solutions generally suffer from limited size reduction effects, reduced operating bandwidth, increased structural design complexity, and increased manufacturing costs, failing to achieve efficient miniaturization of antennas while ensuring broadband performance, and making it difficult to meet the compact integration requirements of modern wireless communication systems.

[0004] Therefore, there is an urgent need to develop a new miniaturization technology for metasurface antennas, which can effectively reduce the overall size of the antenna while ensuring that its broadband performance advantage is not lost, thus solving the technical problem that it is difficult to balance miniaturization and broadband performance in existing metasurface antennas. Summary of the Invention

[0005] Objective: To address the aforementioned technical problems in the prior art, this invention provides a broadband miniaturized metasurface antenna based on a double-layer planar spiral structure. This antenna enhances the equivalent inductance of the metasurface elements by employing a nested planar spiral structure and strengthens the equivalent capacitance using a double-layer structure, thereby effectively reducing the resonant frequency of the metasurface antenna. Thus, this invention can significantly reduce the overall size of the metasurface antenna while maintaining a wide impedance bandwidth and good radiation performance.

[0006] Technical Solution: The present invention provides a broadband miniaturized metasurface antenna based on a dual-layer planar spiral structure, comprising a multi-layer stacked structure, specifically including a four-layer metal structure and a three-layer dielectric substrate structure; the four metal layers are a first metasurface layer, a second metasurface layer, a metal ground layer with coupling gaps, and a microstrip feed layer; the three dielectric substrates are an upper dielectric substrate, a middle dielectric substrate, and a lower dielectric substrate, each dielectric substrate being arranged sequentially from top to bottom, and the four metal layers being attached to the surface of their respective dielectric substrates; the upper dielectric substrate has through-hole metal vias for electrical interconnection between the first and second metasurface layers; both the first and second metasurface layers are composed of several periodically arranged nested planar spiral metal patches.

[0007] Furthermore, the nested planar spiral metal patch consists of an outer metal square ring and an inner planar spiral structure, both located in the same plane; the planar spiral structure can be any one of a square spiral, a circular spiral, or a polygonal spiral.

[0008] Furthermore, the first and second metasurface layers are parallel to each other and have the same period. The geometric centers of the nested planar spiral metal patches at corresponding positions in the upper and lower layers are vertically electrically connected through metal vias to form a double-layer inductively loaded metasurface unit.

[0009] Furthermore, the first metasurface layer is attached to the upper surface of the upper dielectric substrate, the second metasurface layer is attached to the upper surface of the middle dielectric substrate, the metal ground layer is attached to the upper surface of the lower dielectric substrate, and the microstrip feed layer is attached to the lower surface of the lower dielectric substrate.

[0010] Furthermore, the metal ground layer has coupling gaps etched in the middle, and the coupling gaps can be any one of rectangular, dumbbell-shaped or butterfly-shaped; the microstrip feeder layer adopts a Y-shaped, rectangular or fan-shaped microstrip line structure, and achieves electromagnetic energy coupling with the first metasurface layer and the second metasurface layer through the coupling gaps.

[0011] Furthermore, the first and second metasurface layers are composed of 16 nested planar spiral metal patches arranged in a 4×4 periodic array.

[0012] Furthermore, all three dielectric substrates are made of Rogers 4003C material, with a relative permittivity of 3.38 and a loss tangent of 0.0027; the overall physical dimensions of the antenna are 25mm × 25mm × 4.266mm, and the -10dB impedance bandwidth covers 4.3GHz to 6GHz.

[0013] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0014] 1. This invention proposes for the first time a double-layer inductively loaded metasurface structure. By nesting a metal spiral inside a metal ring and electrically connecting the upper and lower metal spirals using metal vias to improve the equivalent inductive reactance, inductive loading is introduced into the metasurface, effectively reducing the resonant frequency and realizing a compact inductively loaded metasurface radiation structure.

[0015] 2. The double-layer inductively loaded metasurface structure proposed in this invention can simultaneously utilize the equivalent capacitance formed between the two metasurface layers to introduce capacitive loading, thereby achieving a reduction in metasurface size while maintaining wide impedance bandwidth characteristics.

[0016] 3. The metasurface antenna structure proposed in this invention is compact, with an overall electrical size of only 0.5λ. h ×0.5λ h ×0.085λ h , (λ h (The free space wavelength corresponding to the highest operating frequency of the antenna), and the relative bandwidth reaches 33%. Compared with common metasurface antennas, it solves the technical problem of balancing miniaturization and broadband performance.

[0017] 4. The nested planar spiral structure used in this invention can change its equivalent inductance value by adjusting parameters such as the number of turns and line width of the spiral. Furthermore, the nested planar spiral metal patch used for inductor loading can adopt various structural forms such as square spiral, circular spiral, or polygonal spiral, introducing more degrees of freedom for the design of metasurface antennas with different frequency bands and performance requirements.

[0018] 5. The present invention has a compact structure, simple processing technology, low manufacturing cost, and is easy to expand arrays and integrate with wireless systems, thus having high engineering practical value. Attached Figure Description

[0019] Figure 1 A schematic diagram of the overall structure of a broadband miniaturized metasurface antenna; Figure 2 Side view of a broadband miniaturized metasurface antenna; Figure 3 This is a top view of a double-nested planar spiral metasurface unit. Figure 4 Top view of a 4×4 periodically arranged metasurface layer; Figure 5 This is a schematic diagram of the feeding structure for a metasurface antenna. Figure 6 Figure 1 shows the simulation results of the metasurface antenna's reflection coefficient and side-fire gain. Figure 7 The simulation results of the E-plane and H-plane radiation patterns of the metasurface antenna at the resonant frequency of 4.56 GHz are shown. Figure 8The simulation results show the E-plane and H-plane radiation patterns of the metasurface antenna at the resonant frequency of 5.68 GHz.

[0020] Explanation of reference numerals: 1-First metasurface layer, 2-Nested planar spiral metal patch, 3-Metal via, 4-Upper dielectric substrate, 5-Second metasurface layer, 6-Middle dielectric substrate, 7-Metal ground layer, 8-Coupling gap, 9-Lower dielectric substrate, 10-Microstrip feeder layer. Detailed Implementation

[0021] A broadband miniaturized metasurface antenna based on a double-layer planar helical structure is shown in the following figures: Figure 1 and Figure 2 As shown, the antenna, from top to bottom, consists of: a first metasurface layer 1, an upper dielectric substrate 4, a second metasurface layer 5, an intermediate dielectric substrate 6, a metal ground layer 7, a lower dielectric substrate 9, and a microstrip feed layer 10. The upper dielectric substrate 4 has metal vias 3 for vertically connecting the first metasurface layer 1 and the second metasurface layer 5. The metal ground layer 7 has coupling gaps etched in the middle.

[0022] All three dielectric substrates are made of Rogers 4003C material with a relative permittivity of 3.38 and a loss tangent of 0.0027. The length L and width W of the dielectric substrates are both 25 mm. From top to bottom, the thicknesses of the upper dielectric substrate 4, the middle dielectric substrate 6, and the lower dielectric substrate 9 are h1=0.203 mm, h2=3.25 mm, and h3=0.813 mm, respectively, and the overall thickness of the antenna is 4.266 mm.

[0023] The metasurface radiative unit adopts a double-layer nested planar spiral metasurface unit, with the structure as follows: Figure 3 As shown, this metasurface unit consists of an outer square ring and an inner planar spiral structure, both located in the same plane, forming an equivalent inductance structure. Specifically, the square ring has a length wp = 5 mm, the square spiral coil has 5 turns, the width of both the square ring and the spiral is w = 0.2 mm, the spiral gap is s = 0.2 mm, and the diameter of the metal via 3 is D = 0.2 mm.

[0024] Top view of metasurface layer as shown Figure 4As shown, the antenna is composed of 16 nested planar spiral metal patches 2 arranged in a 4×4 periodic array with an array period p = 5.4 mm and a gap g = 0.4 mm between adjacent metasurface units. The nested planar spiral metal patches 2 at corresponding positions in the upper and lower layers are vertically electrically connected at their geometric centers via metal vias 3 to achieve series enhancement of the equivalent inductance. Simultaneously, the interlayer distributed capacitance formed between the two metasurface layers introduces capacitive loading within the metasurface. Through the loading of the equivalent inductance and equivalent capacitance, the resonant frequency of the metasurface unit can be effectively reduced, thereby achieving miniaturization of the metasurface antenna size while maintaining broadband characteristics.

[0025] The power supply structure adopts a slot-coupled power supply form with a Y-shaped microstrip line and a rectangular slot, as shown in the figure below. Figure 5 As shown, a rectangular coupling slot 8 is etched at the center of the metallic ground layer 7, with a length Ls = 13.8 mm and a width Ws = 1 mm. The parameters of the microstrip feed layer 10 are as follows: main microstrip line length Ls1 = 6.5 mm, width Ws1 = 2 mm; branch stub length Ls2 = 11.2 mm, width Ws3 = 0.6 mm; center-to-center distance between the two branch stubs Ws2 = 7.7 mm; extension length of the stub end beyond the coupling slot Ls3 = 4.7 mm. Through the optimized design of the above parameters, this feed structure can achieve good impedance matching with the metasurface antenna, thereby obtaining wideband operating characteristics.

[0026] Figure 6 The simulation results of the reflection coefficient and side-fire gain of the broadband miniaturized metasurface antenna provided by this invention are shown. The specific antenna performance is as follows: the -10dB impedance bandwidth covers 4.3GHz to 6GHz, with a relative bandwidth of 33%. There are two resonant frequencies within the operating band, 4.56GHz and 5.68GHz, and the dual-mode resonant operation enables the metasurface antenna to achieve broadband performance. All radiation within the operating band is side-fire, with stable gain in the side-fire direction, a maximum gain of 6.4dBi, and in-band gain fluctuation of less than 2.4dB. The free-space wavelength λ corresponding to the highest operating frequency of 6GHz is... h (λ) h Based on a radius of 50mm, the electrical size of the antenna is only 0.5λ. h ×0.5λ h ×0.085λ h The metasurface antenna proposed in this invention achieves a significant reduction in electrical size, while maintaining good broadband characteristics during miniaturization.

[0027] Figure 7 and Figure 8The figures show the far-field radiation patterns of the antenna in the E-plane and H-plane at the two resonant frequencies of 4.56 GHz and 5.68 GHz, respectively. As can be seen from the figures, the antenna radiation direction is stable, and the cross-polarization suppression effect is good, meeting the requirements of modern wireless communication systems.

[0028] In summary, the broadband miniaturized metasurface antenna proposed in this invention has the characteristics of compact structure, wide impedance bandwidth, stable high gain, and low processing cost.

[0029] This invention introduces a nested planar spiral metal structure, utilizing its high inductive reactance to achieve significant equivalent inductance loading within a limited area. Furthermore, by stacking two layers of metasurfaces and vertically connecting them via metal vias, the upper and lower spiral structures are connected in series to enhance the equivalent inductance. Simultaneously, the interlayer distributed capacitance formed between the two metasurfaces introduces capacitive loading. Thus, this invention significantly reduces the resonant frequency of the metasurface antenna while maintaining its broadband characteristics, achieving effective size reduction and fulfilling the design goal of broadband miniaturization.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, optimizations, etc., made to the technical solution of the present invention within the scope of the inventive concept and claims of the present invention should be included within the scope of protection of the present invention.

Claims

1. A broadband miniaturized metasurface antenna based on a double-layer planar helical structure, characterized in that, The structure includes a multi-layer stacked structure, specifically comprising a four-layer metal structure and a three-layer dielectric substrate structure. The four-layer metal structure consists of a first metasurface layer (1), a second metasurface layer (5), a metal ground layer (7) with coupling gaps (8), and a microstrip feed layer (10). The three-layer dielectric substrate consists of an upper dielectric substrate (4), an intermediate dielectric substrate (6), and a lower dielectric substrate (9). Each dielectric substrate is arranged sequentially from top to bottom, and the four-layer metal structure is attached to the surface of the corresponding dielectric substrate. The upper dielectric substrate (4) has a through-hole metal via (3) inside, which is used to realize the electrical interconnection between the first metasurface layer (1) and the second metasurface layer (5). Both the first metasurface layer (1) and the second metasurface layer (5) are composed of a number of periodically arranged nested planar spiral metal patches (2).

2. The broadband miniaturized metasurface antenna based on a double-layer planar helical structure according to claim 1, characterized in that, The nested planar spiral metal patch (2) consists of an outer square ring and an inner planar spiral structure, both located on the same plane; the planar spiral structure can be any one of a square spiral, a circular spiral or a polygonal spiral.

3. A broadband miniaturized metasurface antenna based on a double-layer planar helical structure according to claim 1, characterized in that, The first metasurface layer (1) and the second metasurface layer (5) are parallel to each other and have the same period. The geometric centers of the nested planar spiral metal patches (2) at corresponding positions of the upper and lower layers are vertically electrically connected through metal vias (3) to form a double-layer inductively loaded metasurface unit.

4. A broadband miniaturized metasurface antenna based on a double-layer planar spiral structure according to claim 1, characterized in that, The first metasurface layer (1) is attached to the upper surface of the upper dielectric substrate (4), the second metasurface layer (5) is attached to the upper surface of the middle dielectric substrate (6), the metal ground layer (7) is attached to the upper surface of the lower dielectric substrate (9), and the microstrip feed layer (10) is attached to the lower surface of the lower dielectric substrate (9).

5. A broadband miniaturized metasurface antenna based on a double-layer planar spiral structure according to claim 1, characterized in that, The metal layer (7) has a coupling gap (8) etched in the middle. The coupling gap (8) can be any one of rectangular, dumbbell-shaped or butterfly-shaped. The microstrip feeder layer (10) adopts a Y-shaped, rectangular or fan-shaped microstrip line structure. It achieves electromagnetic energy coupling with the first metasurface layer (1) and the second metasurface layer (5) through the coupling gap (8).

6. A broadband miniaturized metasurface antenna based on a double-layer planar helical structure according to claim 1, characterized in that, The first metasurface layer (1) and the second metasurface layer (5) are composed of 16 nested planar spiral metal patches (2) arranged in a 4×4 periodic array.

7. A broadband miniaturized metasurface antenna based on a double-layer planar helical structure according to claim 1, characterized in that, The three-layer dielectric substrate is made of Rogers 4003C material, with a relative permittivity of 3.38 and a loss tangent of 0.0027. The overall physical dimensions of the antenna are 25mm×25mm×4.266mm, and the -10dB impedance bandwidth covers 4.3GHz to 6GHz.

Images