Metasurface filtering antenna with high out-of-band rejection

Abstract

The invention discloses a metasurface filtering antenna with high out-of-band rejection. The metasurface filtering antenna comprises a first dielectric substrate, a bonding layer and a second dielectric substrate which are sequentially arranged from top to bottom, wherein the central position of the upper surface of the first dielectric substrate is provided with a metasurface structure, the metasurface structure comprises four same rectangular metal patches, and the four rectangular metal patches are arranged in a 2 * 2 array; the upper surface of the second dielectric substrate is of a defected ground structure, and a rectangular gap and four U-shaped grooves are etched in the center of the defected ground structure, wherein the four U-shaped grooves are symmetrically formed in the two sides of the rectangular gap at equal intervals; the lower surface of the second dielectric substrate is a feed structure, and the feed structure comprises a microstrip line and an I-shaped branch strip connected with the microstrip line; the first dielectric substrate and the second dielectric substrate are connected through a bonding layer. The metasurface filtering antenna can achieve good filtering and radiation performance in a millimeter wave frequency band, and meanwhile is simple in structure and low in machining difficulty, thereby being beneficial to achieving miniaturization design of a millimeter wave system.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency microwave technology, and in particular to a metasurface filtering antenna with high out-of-band suppression. Background Art

[0002] With the rapid development of technologies such as 5G communications, millimeter-wave radar, and satellite communications, the demand for high-performance antennas in high-frequency communication systems is increasing. The millimeter-wave band, with its advantages of high bandwidth, low latency, and high capacity, as well as its low interference and stable signal transmission, is well-suited for use in scenarios such as 5G, the Internet of Things, and autonomous driving. Filter antennas, as antennas with integrated filtering capabilities, not only effectively improve the system's frequency selectivity and anti-interference capabilities, but also reduce system size, meeting the demand for miniaturization of communication systems. Therefore, they hold significant application value in modern communication systems.

[0003] Integrated substrate waveguides are widely used and can achieve high selectivity, but they suffer from high losses and low efficiency. Gap waveguides can address these issues, but gap waveguide structures are typically large and difficult to integrate. Microstrip line feed networks, widely used in modern wireless communication systems, have a simple structure and can be integrated with other microwave circuits. They are also highly flexible, and with a reasonable design, microstrip line transmission can achieve low losses. Metasurface antennas can also flexibly manipulate electromagnetic waves, achieving higher radiation efficiency, wider bandwidth, and stronger beam steering capabilities. While achieving miniaturization and a low-profile design, they also support multi-band operation and high-gain performance. Therefore, a filtering antenna that maintains a low profile while also having good filtering and radiation performance is needed for application in millimeter-wave communication systems. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, a first object of the present invention is to provide a metasurface filtering antenna with high out-of-band suppression.

[0005] To achieve the above-mentioned object, the first embodiment of the present invention proposes a metasurface filtering antenna with high out-of-band suppression, comprising: a first dielectric substrate, an adhesive layer, and a second dielectric substrate arranged in sequence from top to bottom; wherein,

[0006] A metasurface structure is provided at the center of the upper surface of the first dielectric substrate, wherein the metasurface structure includes four identical rectangular metal patches, and the four rectangular metal patches are arranged in a 2×2 array;

[0007] The upper surface of the second dielectric substrate is a defective ground structure, wherein a rectangular gap is etched in the center of the defective ground structure and four U-shaped grooves are symmetrically and evenly spaced on both sides of the rectangular gap;

[0008] The lower surface of the second dielectric substrate is a feeding structure, and the feeding structure includes a microstrip line and an I-shaped branch strip connected to the microstrip line;

[0009] The first dielectric substrate and the second dielectric substrate are connected via the adhesive layer.

[0010] In addition, the metasurface filtering antenna with high out-of-band suppression according to the above embodiment of the present invention may also have the following additional technical features:

[0011] According to an embodiment of the present invention, the four rectangular metal patches are centrosymmetric about a geometric center point of the upper surface of the first dielectric substrate, and the distances between any two of the rectangular metal patches are the same.

[0012] According to one embodiment of the present invention, the rectangular gaps are distributed longitudinally at the center of the defective ground structure and are centrosymmetrical about the geometric center point of the defective ground structure.

[0013] According to one embodiment of the present invention, the microstrip line is laterally distributed along the geometric center point of the lower surface of the second dielectric substrate, the center of the vertical branch of the I-shaped branch strip is the geometric center point of the lower surface of the second dielectric substrate, the microstrip line intersects vertically with the vertical branch of the I-shaped branch strip, and the I-shaped branch strip is symmetrical about the microstrip line.

[0014] According to one embodiment of the present invention, the material of the first dielectric substrate and the second dielectric substrate is Rogers RO4003C, with a dielectric constant of 3.55, a relative magnetic permeability of 1, and a loss tangent of 0.0027.

[0015] According to one embodiment of the present invention, the material of the adhesive layer is Rogers RO4450F, with a dielectric constant of 3.7, a relative magnetic permeability of 1, and a loss tangent of 0.004.

[0016] According to an embodiment of the present invention, the materials of the metasurface structure, the defective ground structure, and the feeding structure are all copper, silver, or gold of a printed circuit.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] Traditional filtering antenna implementations typically use the antenna as the final stage of a filter or load a filtering structure onto the feed structure to achieve filtering performance. This typically results in a larger antenna size and a taller profile. The present invention achieves filtering performance on microstrip lines and metal ground gaps. This metasurface antenna achieves high-frequency filtering characteristics by etching four U-shaped grooves into the ground plane, while adding an I-shaped structure near the gap on the feed line to achieve low-frequency filtering characteristics. This results in high out-of-band suppression.

[0019] This antenna has a maximum gain of 5.5dBi at 28GHz and an out-of-band suppression level of about 20dB.

[0020] The antenna has a simple structure, is easy to manufacture, and has relatively low cost and weight.

[0021] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 2 is a schematic structural diagram of a metasurface filtering antenna with high out-of-band suppression according to an embodiment of the present invention;

[0023] Figure 2 is a top view of a first dielectric substrate according to an embodiment of the present invention;

[0024] Figure 3 is a schematic structural diagram of a defective ground structure according to an embodiment of the present invention;

[0025] Figure 4 is a top view of a feeding structure according to an embodiment of the present invention;

[0026] Figure 5 is an S-parameter curve of a metasurface filtering antenna with high out-of-band suppression according to an embodiment of the present invention;

[0027] Figure 6 is a gain curve of a metasurface filtering antenna with high out-of-band suppression according to an embodiment of the present invention;

[0028] Reference numerals:

[0029] 1. First dielectric substrate; 11. Metasurface structure; 111. Rectangular metal patch; 2. Second dielectric substrate; 21. Defective ground structure; 211. Rectangular gap; 212. U-shaped groove; 22. Feed structure; 221. Microstrip line; 222. I-shaped branch strip; 3. Adhesive layer. DETAILED DESCRIPTION

[0030] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0031] The following describes a metasurface filtering antenna with high out-of-band suppression proposed in an embodiment of the present invention with reference to the accompanying drawings.

[0032] like Figures 1 to 4As shown, a metasurface filtering antenna with high out-of-band suppression according to an embodiment of the present invention includes: a first dielectric substrate 1, an adhesive layer 3, and a second dielectric substrate 2 arranged in sequence from top to bottom; wherein a metasurface structure 11 is provided at the center of the upper surface of the first dielectric substrate 1, and the metasurface structure 11 includes four identical rectangular metal patches 111, and the four rectangular metal patches 111 are arranged in a 2×2 array; the upper surface of the second dielectric substrate 2 is a defective ground structure 21, and a rectangular gap 211 is etched in the center of the defective ground structure 21, and four U-shaped grooves 212 are symmetrically and evenly spaced on both sides of the rectangular gap 211; the lower surface of the second dielectric substrate 2 is a feeding structure 22, and the feeding structure 22 includes a microstrip line 221 and an I-shaped branch strip 222 connected to the microstrip line 221; the first dielectric substrate 1 and the second dielectric substrate 2 are connected by the adhesive layer 3.

[0033] Specifically, the multilayer filtering antenna provided by the present invention adopts a super-surface structure 11 composed of four rectangular metal patches 111 on the upper layer, a defective ground structure 21, a double-layer dielectric substrate design, and an innovative I-shaped branch strip 222 structure added to the end of the microstrip line 221 close to the rectangular gap 211 to achieve the radiation function. Its working principle is as follows: the feeding structure 22 transmits electromagnetic energy to the super-surface structure 11 through the microstrip line 221, exciting the rectangular metal patch 111 to resonate; at the same time, the I-shaped branch strip 222 on the lower surface of the second dielectric substrate 2 forms a resonance point, thereby effectively expanding the antenna working bandwidth. The synergistic effect of the multilayer dielectric structure (i.e., the first dielectric substrate 1, the adhesive layer 3, and the second dielectric substrate 2) optimizes the electromagnetic field distribution and improves the energy coupling efficiency between layers.

[0034] According to one embodiment of the present invention, Figure 2 As shown, the four rectangular metal patches 111 are centrosymmetric about the geometric center point of the upper surface of the first dielectric substrate 1 , and the distances between any two of the rectangular metal patches 111 are the same.

[0035] According to one embodiment of the present invention, Figure 3 As shown, the rectangular gaps 211 are distributed longitudinally in the center of the defective ground structure 21 and are symmetrical about the geometric center point of the defective ground structure 21 .

[0036] Specifically, the present invention effectively improves antenna performance and achieves filtering characteristics by etching a gap and four U-shaped grooves 212 in the defective ground structure 21. The structure changes the ground plane current distribution through the four U-shaped grooves 212, generating a radiation zero point at the upper edge. Its out-of-band suppression characteristics are derived from the equivalent LC resonant circuit of the defective ground structure 21, which exhibits inductive or capacitive behavior at specific frequencies. By disturbing the ground current path, the near-field distribution is significantly optimized. Therefore, an upper edge radiation zero point fn1 is generated at the upper edge of the passband at 30.7GHz, and a high suppression level of more than 30dB can be achieved.

[0037] According to one embodiment of the present invention, Figure 4 As shown, the microstrip line 221 is laterally distributed along the geometric center point of the lower surface of the second dielectric substrate 2, the center of the vertical branch of the I-shaped branch strip 222 is the geometric center point of the lower surface of the second dielectric substrate 2, the microstrip line 221 intersects vertically with the vertical branch of the I-shaped branch strip 222, and the I-shaped branch strip 222 is symmetrical about the microstrip line 221.

[0038] Specifically, the present invention adds an I-shaped branch strip 222 at one end of the feeder near the rectangular gap 211. Loading the I-shaped branch strip 222 on the feeder can achieve low-frequency filtering characteristics, mainly through its unique distributed LC resonant network structure: the horizontal beams of the I-shaped branch strip 222 form a parallel capacitor, and the vertical branches form a series inductor, which together produce an impedance mutation at a specific frequency. The low-frequency signal is suppressed due to inductive reflection, while the high-frequency signal passes capacitively. This structure simultaneously excites the fundamental mode and the odd and even modes, and widens the stopband through multi-mode coupling; the horizontal beams concentrate the electric field to suppress high-frequency strays, the vertical branches guide the current to extend the path to enhance low-frequency reflection, and the structural gap accurately controls the roll-off characteristics. By introducing the I-shaped branch strip 222, a radiation zero point f is introduced at 25.2GHz near the lower edge of the passband. n2 At the same time, because the I-shaped branch strip 222 is directly below the defective ground structure 21, the two are coupled with each other, generating a new lower edge radiation null at 24.2 GHz.

[0039] According to one embodiment of the present invention, the material of the first dielectric substrate 1 and the second dielectric substrate 2 is Rogers RO4003C, which has a dielectric constant of 3.55, a relative magnetic permeability of 1, and a loss tangent of 0.0027.

[0040] In one example, the material of the first dielectric substrate 1 is Rogers RO4003C, with a dielectric constant of 3.55, a relative magnetic permeability of 1, a loss tangent of 0.0027, a thickness of 0.813 mm, a width W of 10 mm, and a length L of 10 mm; the material of the second dielectric substrate 2 is Rogers RO4003C, with a dielectric constant of 3.55, a relative magnetic permeability of 1, a loss tangent of 0.0027, a thickness of 0.203 mm, a width W of 10 mm, and a length L of 10 mm.

[0041] According to one embodiment of the present invention, the material of the adhesive layer 3 is Rogers RO4450F, with a dielectric constant of 3.7, a relative magnetic permeability of 1, a loss tangent of 0.004, a thickness of 0.18 mm, a width W of 10 mm, and a length L of 10 mm.

[0042] According to one embodiment of the present invention, the materials of the metasurface structure 11 , the defective ground structure 21 , and the feeding structure 22 are all copper, silver, or gold of a printed circuit.

[0043] Reference below Figures 1 to 6 A metasurface filtering antenna with high out-of-band suppression according to a specific embodiment of the present invention is described in detail.

[0044] The main dimensions of the antenna are as follows: the length l0 of the metasurface structure 11 is 3.25 mm, the spacing g between the four metal patches is 0.25 mm, the length ls of the rectangular slot 211 of the defective ground structure 21 is 2.95 mm, the slot width w1 is 0.1 mm, the distance d1 between the U-shaped slots on one side of the rectangular slot 211 is 1 mm, the distance d2 between the U-shaped slots on both sides of the rectangular slot 211 is 1 mm, the length l1 of the U-shaped slot along the wide side of the rectangular slot 211 is 1.03 mm, the length l2 along the long side of the rectangular slot 211 is 1.1 mm, the width w2 of the U-shaped slot is 0.1 mm, the length l1 of the microstrip line 221 in the feeding structure 22 is 0. f is 5.5 mm, and the width w of the microstrip line 221 is f The length l of the I-shaped branch strip 222 (i.e., vertical branch) perpendicular to the microstrip line 221 is 0.392 mm. z1 3.2mm, width w z1 The length l of the I-shaped branch strip 222 (i.e., two horizontal beams) parallel to the feeding microstrip line 221 is 0.2 mm. z2 3.4mm, width w z2 0.1mm.

[0045] Combine Figure 5 It can be seen that the center frequency of the antenna is 28 GHz, the operating frequency band is 26.1 GHz-29.9 GHz, the in-band reflection coefficient |S11| is lower than -14 dB, the -10 dB bandwidth of the antenna is 3.8 GHz, and the relative bandwidth is 13.6%. Figure 6 It can be seen from the figure that the antenna has a maximum gain of 5.5dBi at 28GHz, an out-of-band suppression level of about 20dB, and good filtering performance.

[0046] The high out-of-band suppression metasurface filtering antenna of an embodiment of the present invention comprises two dielectric substrates. The second dielectric substrate 2 couples energy to the metasurface structure 11 of the first dielectric substrate 1 via a central slit. Four U-shaped grooves 212 and a rectangular slot 211 are etched into the defective ground structure 21 to form a radiation null at high frequencies. Furthermore, an I-shaped branch strip 222 is added to the end of the microstrip line 221 on the lower surface of the second dielectric substrate 2, near the rectangular slot 211, to improve low-frequency out-of-band suppression. The resulting antenna has a maximum gain of 5.5 dBi at 28 GHz and an out-of-band suppression level of approximately 20 dB.

[0047] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0049] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0050] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A metasurface filtering antenna with high out-of-band suppression, characterized in that: include: The first dielectric substrate, the adhesive layer and the second dielectric substrate are arranged in sequence from top to bottom; wherein, A metasurface structure is provided at the center of the upper surface of the first dielectric substrate, wherein the metasurface structure includes four identical rectangular metal patches, and the four rectangular metal patches are arranged in a 2×2 array; The upper surface of the second dielectric substrate is a defective ground structure, wherein a rectangular gap is etched in the center of the defective ground structure and four U-shaped grooves are symmetrically and evenly spaced on both sides of the rectangular gap; The lower surface of the second dielectric substrate is a feeding structure, and the feeding structure includes a microstrip line and an I-shaped branch strip connected to the microstrip line; The first dielectric substrate and the second dielectric substrate are connected via the adhesive layer.

2. The metasurface filtering antenna with high out-of-band suppression according to claim 1, characterized in that: The four rectangular metal patches are centrosymmetric about the geometric center point of the upper surface of the first dielectric substrate, and the distances between any two of the rectangular metal patches are the same.

3. The metasurface filtering antenna with high out-of-band suppression according to claim 1, characterized in that: The rectangular gaps are distributed longitudinally at the center of the defective ground structure and are centrally symmetrical about the geometric center point of the defective ground structure.

4. The metasurface filtering antenna with high out-of-band suppression according to claim 1, characterized in that: The microstrip line is laterally distributed along the geometric center point of the lower surface of the second dielectric substrate, the center of the vertical branch of the I-shaped branch strip is the geometric center point of the lower surface of the second dielectric substrate, the microstrip line intersects the vertical branch of the I-shaped branch strip perpendicularly, and the I-shaped branch strip is symmetrical about the microstrip line.

5. The metasurface filtering antenna with high out-of-band suppression according to claim 1, characterized in that: The first dielectric substrate and the second dielectric substrate are made of Rogers RO4003C, with a dielectric constant of 3.55, a relative magnetic permeability of 1, and a loss tangent of 0.0027.

6. The metasurface filtering antenna with high out-of-band suppression according to claim 1, characterized in that: The material of the bonding layer is Rogers RO4450F, with a dielectric constant of 3.7, a relative magnetic permeability of 1, and a loss tangent of 0.

004.

7. The metasurface filtering antenna with high out-of-band suppression according to claim 1, characterized in that: The materials of the metasurface structure, the defective ground structure and the feeding structure are all copper, silver or gold of printed circuits.

Images