A broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface

Abstract

This invention discloses a broadband circularly polarized microstrip array antenna based on a hybrid S-shaped aperture and metasurface, belonging to the field of wireless communication antenna technology. The antenna employs a multi-layer stacked structure, comprising, from top to bottom, a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate, and on the surfaces of each substrate are a metasurface radiating layer, a slot coupling layer, a microstrip feed network layer, and a metal grounding shield layer. The metasurface radiating layer is composed of periodically arranged rectangular metal patches; the slot coupling layer is etched with centrally symmetrical S-shaped bends; the microstrip feed network adopts a 2×2 sequential rotation architecture, providing excitation signals of equal amplitude and sequentially 90° phase difference. This invention increases the effective electrical length of magnetic flux through a topology-optimized S-shaped slot structure, achieves ultra-wideband characteristics through the hybrid resonance of slots, patches, and metasurfaces, and compensates for impedance singularities using sequential rotation feed technology, thus achieving wide bandwidth, high gain, high radiation efficiency, and excellent circular polarization performance.

Description

Technical Field

[0001] This invention relates to the field of wireless communication antenna technology, and in particular to a broadband circularly polarized microstrip array antenna based on a hybrid S-shaped aperture and metasurface. Background Technology

[0002] In modern wireless communication systems such as satellite communications, synthetic aperture radar (SAR), and 5G communications, the demand for channel capacity and link stability is increasing. Circularly polarized (CP) antennas have become indispensable due to their inherent advantages in resisting multipath interference and polarization mismatch.

[0003] However, traditional microstrip antennas are limited by their high-Q resonant characteristics, making it difficult to simultaneously achieve broadband performance, high gain, and compact physical size. While traditional techniques such as stacked patches and thick substrates can broaden the bandwidth to some extent, this often comes at the cost of increased surface wave loss and reduced efficiency. In recent years, metasurface (MS) technology has effectively improved the performance of microstrip antennas by introducing subwavelength periodic structures to modulate the amplitude and phase of electromagnetic waves. However, most current research on metasurfaces still uses coaxial probe feeding. In high-frequency applications, the parasitic inductance introduced by long probes can easily lead to deterioration of input impedance characteristics, and vertical interconnect structures not only involve complex manufacturing processes but also face technical challenges in achieving uniform bonding of large-scale arrays.

[0004] In contrast, aperture-coupled feeding technology offers advantages such as non-contact operation, ease of integration, and excellent isolation performance. However, traditional rectangular resonant slots typically require half a wavelength in size to achieve effective energy coupling, which is difficult to achieve in space-constrained compact array designs and can affect the excitation of orthogonal modes required for broadband circular polarization. Summary of the Invention

[0005] The purpose of this invention is to provide a broadband circularly polarized microstrip array antenna based on a hybrid S-shaped aperture and metasurface, which solves the problem that existing microstrip antennas cannot simultaneously achieve wide bandwidth, high gain and excellent impedance matching in a compact space.

[0006] To achieve the above objectives, the present invention provides a broadband circularly polarized microstrip array antenna based on a hybrid S-shaped aperture and metasurface, comprising a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked sequentially from top to bottom, and: A metasurface radiating layer is disposed on the upper surface of the first dielectric substrate and is composed of a periodically arranged rectangular metal patch array; A slot coupling layer is disposed between the first dielectric substrate and the second dielectric substrate, and serves as a common metallic ground layer; a centrally symmetrical S-shaped bend slot is etched on the slot coupling layer corresponding to each radiating unit; A microstrip feed network layer is disposed between the second dielectric substrate and the third dielectric substrate, and adopts a 2×2 sequential rotating feed network architecture to provide excitation signals of equal amplitude and phase difference of 90° to the four sub-arrays. A metallic grounding shielding layer is disposed on the bottom layer of the third dielectric substrate to suppress back radiation and shield external interference.

[0007] Preferably, the metasurface radiation layer is divided into four 2×2 sub-array regions, each containing a 4×4 periodically arranged rectangular metal patch.

[0008] Preferably, the center of each subarray region on the slot coupling layer is etched with a rotationally symmetric pattern consisting of four S-shaped bends, the rotationally symmetric pattern being windmill-shaped.

[0009] Preferably, several straight slots are symmetrically etched around the periphery of each S-shaped bend slot group on the slot coupling layer.

[0010] Preferably, the first dielectric substrate is made of a material with a relative permittivity of 3.48 and a dielectric loss tangent of 0.0027; the second and third dielectric substrates are both made of a material with a relative permittivity of 2.2 and a dielectric loss tangent of 0.001.

[0011] Preferably, the microstrip feed network layer is constructed using multi-stage T-type power dividers and delay lines to form an orthogonal excitation phase gradient that satisfies a 2×2 sequential rotating array structure.

[0012] Preferably, the ends of each feed branch of the microstrip feed network layer are designed as diamond ring structures, with the diamond ring structure facing the corresponding S-shaped bend gap group above.

[0013] Preferably, the metal grounding shield layer has a clearance hole at its center for a coaxial line to pass through, and four centrally symmetrically distributed bottom strips are etched on the periphery of the metal grounding shield layer.

[0014] Preferably, the antenna has a metallized via at its center for connecting a coaxial probe to receive an external excitation signal.

[0015] Preferably, the entire antenna is arranged in a 2×2 sequential rotating array with the metasurface radiating layer, the slot coupling layer and the microstrip feed network layer corresponding to each other, and achieves hybrid resonance broadband characteristics by means of the magnetic dipole mode dominated by the S-shaped bend slot and the parasitic electric resonance mode introduced by the metasurface.

[0016] Therefore, the present invention employs the above-mentioned broadband circularly polarized microstrip array antenna based on a hybrid S-shaped aperture and a metasurface, which has the following beneficial effects: 1) Topology-optimized S-shaped slot structure: By utilizing the geometric bending characteristics of the S-shaped structure, the effective electrical length of the magnetic flux is increased, achieving efficient low-frequency magnetic coupling in a compact space and providing greater freedom for impedance matching.

[0017] 2) Hybrid mode resonance mechanism: By synergistically regulating the slot resonance, patch resonance and the parasitic mode of the metasurface, multiple adjacent resonance points are formed in a wide bandwidth, thereby achieving ultra-wide bandwidth characteristics.

[0018] 3) High-performance array synthesis: Combining 2×2 sequential rotating feed technology, the spatial phase averaging effect of the array is used to effectively compensate for the impedance singularity problem in the band of a single unit.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a side view of the broadband circularly polarized metasurface antenna structure of the present invention; Figure 2 This is a top view of the broadband circularly polarized metasurface antenna structure of the present invention; Figure 3 This is a simulation diagram of the S-parameters of the broadband circularly polarized metasurface antenna of the present invention; Figure 4 This is a gain and axial ratio diagram of the broadband circularly polarized metasurface antenna of the present invention; Figure 5 This is a two-dimensional simulation radiation pattern of the broadband circularly polarized metasurface antenna of the present invention at 4.16 GHz; Figure 6 This is a 5.0GHz two-dimensional simulation radiation pattern of the broadband circularly polarized metasurface antenna of the present invention.

[0021] Figure Labels 1. First dielectric substrate; 2. Rectangular metal patch; 3. Slot coupling layer; 4. Second dielectric substrate; 5. Microstrip feed network layer; 6. Third dielectric substrate; 7. Straight slot; 8. S-shaped bend slot; 9. Bottom long strip slot; 10. Metal grounding shield layer. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] Example 1 like Figure 1 , Figure 2 As shown, this embodiment provides a broadband circularly polarized microstrip array antenna based on a hybrid S-shaped aperture and metasurface. The overall structure adopts a compact multi-layer stacked structure, which is suitable for C-band satellite communication and 5G communication systems.

[0025] The antenna is constructed by stacking a first dielectric substrate 1, a second dielectric substrate 4, and a third dielectric substrate 6 sequentially from top to bottom. Each of the three dielectric substrates has a planar dimension of 100mm × 100mm and thicknesses of 3.14mm, 0.7mm, and 1mm, respectively. The first dielectric substrate 1 uses a substrate with a relative permittivity of 3.48 and a dielectric loss tangent of 0.0027. The second and third dielectric substrates 4 and 6 both use substrates with a relative permittivity of 2.2 and a dielectric loss tangent of 0.001, in order to minimize dielectric loss and improve the overall radiation efficiency of the antenna.

[0026] A metasurface radiating layer is disposed on the top surface of the first dielectric substrate 1. This metasurface radiating layer is composed of multiple rectangular metal patches 2. The entire metasurface radiating layer is divided into four 2×2 sub-array regions. Each sub-array region contains 4×4 periodically arranged rectangular metal patches 2. The length of a single rectangular metal patch 2 is 9.4 mm and the width is 9 mm. This metasurface structure, acting as a parasitic director, can not only introduce high-frequency electrical resonant modes, but also, together with the underlying slot coupling layer 3, form a low-Q Fabry-Pérot resonant cavity, effectively widening the operating bandwidth and significantly improving the antenna gain.

[0027] A slot coupling layer 3 is disposed between the lower surface of the first dielectric substrate 1 and the upper surface of the second dielectric substrate 4. This layer also serves as the common metallic ground layer of the antenna, providing electromagnetic isolation between the upper radiator and the lower feed network. Corresponding to the four sub-array regions, the slot coupling layer 3 has a rotationally symmetric pattern composed of four S-shaped bent slots 8 etched at the center of each region, forming a windmill shape, serving as the main magnetic dipole coupling source for exciting circular polarization. Each S-shaped bent slot 8 has two radii, 3.4 mm and 5.1 mm, respectively. It utilizes geometric bending characteristics to increase the effective electrical length of the magnetic flux, achieving efficient magnetic coupling in the low-frequency band. Around the periphery of each group of S-shaped bent slots 8, multiple straight slots 7 are also symmetrically etched; the auxiliary introduction of straight slots 7 further optimizes the resonant characteristics of the slots and the impedance matching across the entire frequency band.

[0028] A microstrip feed network layer 5 is disposed on the upper surface of the third dielectric substrate 6, located between the second dielectric substrate 4 and the third dielectric substrate 6. The microstrip feed network layer 5 employs a 2×2 sequential rotating feed network architecture, which is constructed from multiple stages of T-shaped power dividers and delay lines. It extends outwards from the center in a 90-degree rotational progression, providing four sub-arrays with orthogonal excitation signals of equal amplitude and sequentially 90° phase difference. The ends of each feed network branch are designed as diamond-shaped ring structures, directly opposite the corresponding eight sets of S-shaped bends above, to achieve optimal energy coupling and impedance conversion. A metallized via is located at the center of the antenna for connecting a coaxial probe to receive external excitation signals.

[0029] The bottom surface of the third dielectric substrate 6 is covered with a metallic grounding shield 10, which effectively suppresses back radiation generated by the microstrip feed network and reduces electromagnetic interference from the external environment. The metallic grounding shield 10 has a center hole for a coaxial cable to pass through, and four centrally symmetrically distributed bottom-layer elongated slots 9 are etched around its periphery. Each bottom-layer elongated slot 9 is 34 mm long and 0.1 mm wide. The loading of the bottom-layer elongated slots 9 further adjusts the antenna's back cavity resonance characteristics and front-to-back ratio, improving overall radiation efficiency.

[0030] The working principle of the antenna in this embodiment is as follows: A coaxial signal is input to the center feed point and passes through the sequentially rotated microstrip feed network layer 5, generating four orthogonal excitation signals with equal amplitude and sequentially 90° phase differences. The signals are efficiently coupled to the S-shaped bend slit 8 and straight slit 7 in the upper common ground layer through the diamond ring structure at the end of the feed branch, exciting a rotating magnetic current. This magnetic current further penetrates the first dielectric substrate 1, exciting the rectangular metal patch 2 at the top to generate an electrical resonance. The antenna forms multiple adjacent resonance points in a wide bandwidth through a hybrid resonance mechanism of the magnetic dipole mode dominated by the S-shaped bend slit 8 and the parasitic electrical resonance mode introduced by the metasurface radiating layer, thereby achieving ultra-wideband characteristics. At the same time, the 2×2 sequential rotating feed technology utilizes the spatial phase averaging effect of the array to effectively compensate for the impedance singularity problem in the band of a single unit, further widening the impedance bandwidth and axial ratio bandwidth, and improving the circular polarization purity.

[0031] The array antenna system was simulated and debugged using electromagnetic simulation software. The S-parameter results are as follows: Figure 3 As shown, the simulation results fully cover the 3.86-6.14GHz frequency band, maintaining good impedance matching of S11<-10dB within this band.

[0032] As attached Figure 4 As shown, the antenna's 3dB axial ratio bandwidth covers the 4.03 to 6.07 GHz frequency band, with a peak gain of 11.3 dBic within the operating frequency band. Furthermore, the antenna's radiation efficiency remains consistently above 90% throughout the entire operating frequency band.

[0033] like Figure 5 , Figure 6 The figures show the two-dimensional simulated radiation patterns of the antenna in the 4.16 GHz and 5.0 GHz frequency bands, respectively. The antenna achieves stable unidirectional radiation through right-hand circular polarization. In all test frequency bands, the right-hand circular polarization component is significantly better than the left-hand circular polarization component, with an isolation of more than 10 dB, which fully verifies the antenna's excellent circular polarization purity.

[0034] Therefore, this invention employs a broadband circularly polarized microstrip array antenna based on a hybrid S-shaped aperture and metasurface. By using a topology-optimized S-shaped slot structure to increase the effective electrical length of the magnetic flux, efficient low-frequency magnetic coupling is achieved within a compact space. Through slot resonance, patch resonance, and parasitic modes of the metasurface, multiple adjacent resonance points are formed within a wide bandwidth, achieving ultra-wideband characteristics. Combined with 2×2 sequential rotating feed technology, the spatial phase averaging effect of the array is utilized to effectively compensate for the impedance singularity problem within a single unit band, achieving broadband, high gain, and excellent circular polarization performance in a compact size.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A broadband circularly polarized microstrip array antenna based on a hybrid S-shaped aperture and metasurface, characterized in that, It includes a first dielectric substrate (1), a second dielectric substrate (4), and a third dielectric substrate (6) stacked sequentially from top to bottom, and: A metasurface radiation layer is disposed on the upper surface of the first dielectric substrate (1) and is composed of a periodically arranged array of rectangular metal patches (2); A slot coupling layer (3) is disposed between the first dielectric substrate (1) and the second dielectric substrate (4) and serves as a common metal ground layer; a centrally symmetrical S-shaped bend slot (8) is etched on the slot coupling layer (3) corresponding to each radiating unit; A microstrip feed network layer (5) is disposed between the second dielectric substrate (4) and the third dielectric substrate (6), and adopts a 2×2 sequential rotating feed network architecture to provide excitation signals with equal amplitude and phase difference of 90° for the four sub-arrays. A metal grounding shielding layer (10) is disposed on the bottom layer of the third dielectric substrate (6) to suppress back radiation and shield external interference.

2. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface as described in claim 1, characterized in that, The metasurface radiation layer is divided into four 2×2 sub-array regions, each containing a 4×4 periodically arranged rectangular metal patch (2).

3. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface as described in claim 2, characterized in that, The center of each subarray region on the slot coupling layer (3) is etched with a rotationally symmetric pattern consisting of four S-shaped bends (8), which are in the shape of a windmill.

4. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface as described in claim 3, characterized in that, On the slot coupling layer (3), several straight slots (7) are symmetrically etched around the periphery of each S-shaped bend slot (8) group.

5. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface as described in claim 1, characterized in that, The first dielectric substrate (1) is made of a material with a relative permittivity of 3.48 and a dielectric loss tangent of 0.0027; the second dielectric substrate (4) and the third dielectric substrate (6) are both made of a material with a relative permittivity of 2.2 and a dielectric loss tangent of 0.

001.

6. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface according to claim 1, characterized in that, The microstrip feed network layer (5) is constructed using multi-stage T-type power dividers and delay lines to form an orthogonal excitation phase gradient that satisfies the 2×2 sequential rotating array structure.

7. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface as described in claim 6, characterized in that, Each feed branch end of the microstrip feed network layer (5) is designed as a diamond ring structure, and the diamond ring structure is directly opposite the corresponding S-shaped bend gap (8) group above.

8. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface according to claim 1, characterized in that, The metal grounding shield (10) has a clearance hole in the center for the coaxial line to pass through, and four bottom strip gaps (9) are etched on the periphery of the metal grounding shield (10) in a centrally symmetrical distribution.

9. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface according to claim 1, characterized in that, The antenna has a metallized via at its center for connecting a coaxial probe to receive external excitation signals.

10. The broadband circularly polarized microstrip array antenna based on hybrid S-shaped aperture and metasurface as described in claims 1-9, characterized in that, The entire antenna is arranged in a 2×2 sequential rotating array with the metasurface radiating layer, the slot coupling layer (3) and the microstrip feed network layer (5) respectively. It achieves hybrid resonance broadband characteristics by means of the magnetic dipole mode dominated by the S-shaped bend slot and the parasitic electric resonance mode introduced by the metasurface.

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