SSPP leaky-wave antenna and design method thereof

Abstract

The invention discloses an SSPP leaky-wave antenna and a design method thereof, and belongs to the technical field of wireless communication, and the antenna comprises a dielectric substrate, and a positive microstrip line and a negative microstrip line which are correspondingly arranged on the upper surface and the lower surface of the dielectric substrate; the positive microstrip line and the negative microstrip line are respectively symmetrical about two current transmission ends; and the SSPP structure of the middle section of the positive microstrip line and the SSPP structure of the middle section of the negative microstrip line are arranged in a way that the groove openings are opposite to each other. According to the invention, high-gain signal radiation and multi-angle beam scanning can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and particularly relates to a SSPP leaky-wave antenna and its design method. Background Art

[0002] With the rapid development of wireless communication technology, the requirements for antenna performance are increasing day by day, especially in terms of multi-band, wide bandwidth, high gain, and beam scanning ability. Traditional antenna designs face many challenges in meeting these requirements, such as limited frequency bands, large gain fluctuations, and insufficient beam scanning angles.

[0003] In recent years, leaky-wave antennas based on surface plasmon polaritons (SSPPs) have gradually become a research hotspot in the field of antenna design due to their unique electromagnetic properties and excellent performance. The SSPP structure can achieve effective localization and directional radiation of electromagnetic waves by periodically modulating the electromagnetic field distribution, providing a new technical approach for antenna design. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a SSPP leaky-wave antenna and its design method to achieve high-gain signal radiation and multi-angle beam scanning.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions:

[0006] In a first aspect, the present invention provides a SSPP leaky-wave antenna, including: a dielectric substrate, and a positive microstrip line and a negative microstrip line correspondingly arranged on the upper and lower surfaces of the dielectric substrate; the positive microstrip line and the negative microstrip line are symmetric about both ends of current transmission; the SSPP structures in the middle sections of the positive microstrip line and the negative microstrip line are arranged with the groove openings facing each other.

[0007] For the aforementioned SSPP leaky-wave antenna, the section between both ends of the negative microstrip line and the SSPP structure in the middle section includes a rectangular feeding structure and a trapezoidal transition structure; current is transmitted from the rectangular feeding structure at one end of the negative microstrip line through the trapezoidal transition structure to the SSPP structure, realizing impedance matching at the port of the SSPP structure.

[0008] For the aforementioned SSPP leaky-wave antenna, the groove depths at both ends of the SSPP structure decrease along both ends respectively.

[0009] For the aforementioned SSPP leaky-wave antenna, it further includes a plurality of metal patches, and the metal patches are uniformly arranged along the groove opening end of the SSPP structure.

[0010] For the aforementioned SSPP leaky-wave antenna, the metal patch is a double semi-elliptical structure, and the double semi-elliptical structure is a closed structure formed by the intersection of two semi-elliptical curves, and the metal patches are staggeredly arranged on the upper and lower surfaces of the dielectric substrate.

[0011] For the aforementioned SSPP leaky-wave antenna, the dielectric substrate uses F4B material, the relative dielectric constant of the dielectric substrate is 3.5, the thickness is 0.5 mm, and the loss tangent is 0.0027; the positive and negative microstrip lines are made of copper, and the thickness of the copper layer is 0.018 mm.

[0012] For the aforementioned SSPP leaky-wave antenna, the width of the positive microstrip line is 4 mm, the width of the rectangular feeding structure of the negative microstrip line is 8 mm and the length is 5 mm, the trapezoidal transition structure is an isosceles trapezoid, the wide side of the rectangular feeding structure is connected to the long bottom of the isosceles trapezoid, the height of the isosceles trapezoid is 15 mm, and the trapezoidal transition structure transitions from the same width as the rectangular feeding structure to the same width as the positive microstrip line.

[0013] For the aforementioned SSPP leaky-wave antenna, the SSPP structure is composed of a plurality of L-shaped structures connected end to end to form a periodic groove, and the groove depths in the middle section of the SSPP structure are the same; the parameters of the L-shaped structure that constitutes the groove in the middle section of the SSPP structure are: outer width p = 6.8 mm, inner width a = 3.5 mm, outer wall height d = 5.0 mm, and inner groove depth h = 2.4 mm.

[0014] For the aforementioned SSPP leaky-wave antenna, the distance r between the intersections of the metal patches' double semi-ellipses is 4 mm, the distance between the metal patches is 8 mm, the distance d between the metal patches is the distance between the midpoints of the two double semi-ellipse intersection distances r, and the horizontal distance d between the metal patches and the SSPP structure on the same surface is 0.3 mm.

[0015] In a second aspect, the present invention provides a design method for an SSPP leaky-wave antenna, including:

[0016] S1: Determine the design objectives of the SSPP leaky-wave antenna;

[0017] S2: Determine the initial parameters of the unit structure that makes up the SSPP structure according to the design objectives in step S1;

[0018] S3: According to the unit structure determined in step S2 and combined with the Floquet theorem, deduce the dispersion relationship and then determine the final parameters of the unit structure;

[0019] S4: According to the SSPP structure composed of the unit structure in step S3 and combined with the Floquet theorem, determine the basic structure of the SSPP leaky-wave antenna, and the basic structure includes: a dielectric substrate, and a positive microstrip line and a negative microstrip line correspondingly arranged on the upper and lower surfaces of the dielectric substrate; the positive microstrip line and the negative microstrip line are respectively symmetric about the two ends of current transmission; the SSPP structure in the middle section of the positive microstrip line and the SSPP structure in the middle section of the negative microstrip line are arranged with the groove openings facing each other;

[0020] S5: Based on the basic structure in step S4 and combined with the Floquet theorem, a double semi-elliptical metal patch is added to optimize the end-fire transmission of the basic structure, and the final SSPP leaky-wave antenna is obtained.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0022] In the present invention, SSPP structures with grooves opposite to each other are respectively arranged on the upper and lower surfaces of the dielectric substrate. Compared with the traditional single-conductor structure, the double-conductor structure of the present invention has a stronger electromagnetic field localization effect and can effectively improve the energy density. Secondly, within the same operating frequency band, this structure can generate a larger phase change amount, increase the beam scanning angle, and achieve high-gain signal radiation and multi-angle beam scanning.

[0023] Based on the Floquet theorem, the present invention deeply explores the design principle and performance optimization method of the double-conductor SSPPs leaky-wave antenna. Through theoretical analysis and numerical simulation, the electromagnetic field distribution characteristics, dispersion relationship, and beam scanning mechanism of the double-conductor SSPPs structure are studied. On this basis, a novel design of the double-conductor SSPPs leaky-wave antenna is proposed. By introducing a double semi-elliptical patch structure, the open stopband effect in the end-fire direction is effectively suppressed, and stable radiation gain and excellent beam scanning performance in a wide frequency band are achieved. The simulation results show that the SSPP leaky-wave antenna of the present invention has a radiation efficiency of more than 82% and a gain greater than 10 dBi in the frequency band of 14.0 GHz - 34.0 GHz. At the same time, it exhibits excellent gain stability in the entire operating frequency band, and the fluctuation range of the maximum gain and the minimum gain value relative to the average gain is controlled within 3 dBi; the main beam direction can be continuously adjusted within the range of -90° to +29°, the scanning angle reaches 119°, and at the same time, a high radiation efficiency and gain stability are maintained in the entire operating frequency band. Description of the Drawings

[0024] Figure 1 is a schematic plan view of the SSPP leaky-wave antenna structure according to an embodiment of the present invention;

[0025] Figure 2 is a schematic plan view of the SSPP leaky-wave antenna structure with a metal patch added according to an embodiment of the present invention;

[0026] Figure 3 is a schematic plan view of the unit structure forming the SSPP structure according to Embodiment 2 of the present invention;

[0027] Figure 4 is a partial schematic view of the three-dimensional model of the double-conductor SSPP structure according to Embodiment 2 of the present invention;

[0028] Figure 5Schematic diagram of the dispersion characteristics curves of the traditional single-conductor SSPP structure and the dual-conductor SSPP structure of Embodiment 2 of the present invention;

[0029] Figure 6 Schematic diagram of the structural adjustment process of the SSPP structure of Embodiment 2 of the present invention;

[0030] Figure 7 is of Embodiment 2 of the present invention Figure 1 Schematic diagram of the high-order harmonic dispersion curve of the SSPP structure;

[0031] Figure 8 is of Embodiment 2 of the present invention Figure 1 Schematic diagram of the simulated S parameters of the SSPP structure;

[0032] Figure 9 is of Embodiment 2 of the present invention Figure 2 Schematic diagram of the simulated S parameters of the SSPP structure;

[0033] Figure 10 is of Embodiment 2 of the present invention Figure 2 Simulated radiation pattern of the SSPP leaky-wave antenna;

[0034] Figure 11 is of Embodiment 2 of the present invention Figure 2 Simulated radiation efficiency diagram of the SSPP leaky-wave antenna;

[0035] Figure 12 is of Embodiment 2 of the present invention Figure 2 Simulated gain diagram of the SSPP leaky-wave antenna;

[0036] Description of reference numerals:

[0037] 1 - dielectric substrate; 2 - positive microstrip line; 3 - negative microstrip line; 31 - rectangular feeding structure; 32 - trapezoidal transition structure; 4 - SSPP structure; 401 - groove; 5 - metal patch. Detailed implementation manners

[0038] The technical solutions of the present invention will be described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific features in the embodiments of the present application and the embodiments are detailed descriptions of the technical solutions of the present application, rather than limitations on the technical solutions of the present application. Without conflict, the technical features in the embodiments of the present application and the embodiments can be combined with each other.

[0039] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0040] Embodiment 1:

[0041] This embodiment introduces an SSPP leaky-wave antenna, as Figure 1 shown, including: a dielectric substrate 1, and a positive microstrip line 2 and a negative microstrip line 3 correspondingly arranged on the upper and lower surfaces of the dielectric substrate 1; the positive microstrip line 2 and the negative microstrip line 3 are symmetric with respect to both ends of current transmission, that is, symmetric about the y-axis; the SSPP structure 4 in the middle section of the positive microstrip line 2 and the SSPP structure 4 in the middle section of the negative microstrip line 3 are arranged with the openings of the grooves 401 facing each other. As Figure 1 shown, the positive microstrip line 2 and the negative microstrip line 3 extend along the x-axis direction, the opening of the groove 401 of the positive microstrip line 2 faces the -y direction, the opening of the groove 401 of the negative microstrip line 3 faces the +y direction, and the SSPP structures 4 on the upper and lower surfaces of the dielectric substrate 1 are rotationally symmetric about the x-axis.

[0042] In the SSPP structure, the double-conductor SSPP exhibits more excellent performance than the single-conductor SSPP due to its stronger electromagnetic field confinement ability and higher energy density. The double-conductor structure can not only significantly improve the dispersion regulation ability of the antenna, but also effectively suppress signal crosstalk and reduce the electromagnetic coupling between transmission lines, thereby improving the signal transmission quality. In addition, the double-conductor SSPP also shows significant advantages in aspects such as beam scanning angle improvement, miniaturization design, and anti-interference performance, providing more flexibility and optimization space for antenna design.

[0043] Leaky-wave antennas usually adopt a two-port structure to ensure that the electromagnetic waves transmitted to the end of the antenna can be absorbed, so that the reflected waves will not affect the radiation direction. As Figure 1 shown, between both ends of the negative microstrip line 3 and the middle-section SSPP structure 4, there are included a rectangular feeding structure 31 and a trapezoidal transition structure 32; the current is transmitted from the rectangular feeding structure 31 at one end of the negative microstrip line 3 through the trapezoidal transition structure 32 to the SSPP structure 4, realizing the impedance matching of the SSPP structure port.

[0044] As Figure 1 shown, the depths of the grooves 401 at both ends of the SSPP structure 4 decrease along both ends respectively, realizing impedance gradual change matching, promoting mode conversion, optimizing the leaky-wave radiation characteristics, and suppressing reflection. This design can effectively improve the radiation efficiency and performance of the SSPP leaky-wave antenna.

[0045] As Figure 2 shown, the SSPP leaky-wave antenna further includes a plurality of metal patches 5, and the metal patches 5 are uniformly arranged along the opening ends of the grooves 401 of the SSPP structure 4. The addition of the metal patches 5 can improve the open-stopband effect that occurs during the broadside direction scanning of the SSPP leaky-wave antenna.

[0046] As Figure 2As shown, the metal patch 5 has a double semi-elliptical structure, which is a closed structure formed by the intersection of two semi-elliptical curves. The metal patch 5 is symmetrically arranged on the upper and lower surfaces of the dielectric substrate 1.

[0047] In this embodiment, the dielectric substrate 1 is made of F4B material, with a relative dielectric constant of 3.5, a thickness of 0.5 mm, and a tangent of the loss angle of 0.0027. The positive and negative microstrip lines are made of copper, and the thickness of the copper layer is 0.018 mm. The width of the positive microstrip line 2 is 4 mm, the width of the rectangular feeding structure 31 of the negative microstrip line 3 is 8 mm and the length is 5 mm. The trapezoidal transition structure 32 is an isosceles trapezoid, and the wide side of the rectangular feeding structure 31 is connected to the long bottom of the isosceles trapezoid. The height of the isosceles trapezoid is 15 mm, and the trapezoidal transition structure 32 transitions from the same width as the rectangular feeding structure 31 to the same width as the positive microstrip line 2. The SSPP structure 4 is composed of multiple L-shaped structures connected end to end to form periodic grooves 401, and the depths of the grooves 401 in the middle section of the SSPP structure 4 are the same. The parameters of the L-shaped structure forming the grooves 401 in the middle section of the SSPP structure 4 are: outer width p = 6.8 mm, inner width a = 3.5 mm, outer wall height d = 5.0 mm, and inner groove depth h = 2.4 mm. The distance between the intersections of the double semi-ellipses of the metal patch 5 is 4 mm, the distance between the metal patches 5 is 8 mm, and the distance between the metal patches 5 is the distance between the midpoints of the distances between the intersections of the two double semi-ellipses. The horizontal distance between the metal patch 5 and the SSPP structure 4 on the same surface is 0.3 mm.

[0048] Embodiment 2:

[0049] Based on the same inventive concept as Embodiment 1, this embodiment introduces a design method for an SSPP leaky wave antenna, including:

[0050] S1: Determine the design objectives of the SSPP leaky wave antenna;

[0051] S2: Determine the initial parameters of the unit structure forming the SSPP structure according to the design objectives in step S1;

[0052] S3: According to the unit structure determined in step S2 and combining with the Floquet theorem, deduce the dispersion relationship and then determine the final parameters of the unit structure;

[0053] S4: According to the SSPP structure composed of the unit structure in step S3 and combining with the Floquet theorem, determine the basic structure of the leaky wave antenna. The basic structure includes: the dielectric substrate 1, and the positive microstrip line 2 and the negative microstrip line 3 correspondingly arranged on the upper and lower surfaces of the dielectric substrate 1; the positive microstrip line 2 and the negative microstrip line 3 are respectively symmetric about the two ends of current transmission; the SSPP structure 4 in the middle section of the positive microstrip line 2 and the SSPP structure 4 in the middle section of the negative microstrip line 3 are arranged with the openings of the grooves 401 facing each other;

[0054] S5: Based on the basic structure in step S4 and combined with the Floquet theorem, a metal patch 5 with a double semi-elliptical structure is added to optimize the edge radiation transmission of the basic structure, and the final SSPP leaky-wave antenna is obtained.

[0055] The following combines specific simulation examples to further elaborate on this embodiment.

[0056] As Figure 3 shown, it is the schematic diagram of the unit structure in step S2 of this embodiment. The initial parameters are: outer width p = 6.8 mm, inner width a = 1.2 mm, outer wall height d = 5.0 mm, and inner groove depth h = 2.4 mm.

[0057] By comparing and analyzing the traditional single-conductor SSPP and the double-conductor SSPP structure designed in this embodiment, the electromagnetic characteristic differences between the two configurations are deeply explored. Figure 4 It shows a partial structure of the three-dimensional model of the double-conductor SSPP structure. The double-conductor SSPP structures in this embodiment are arranged corresponding to each other up and down. The structures of the two SSPP structures 4 are the same and the groove openings are opposite to each other.

[0058] The dispersion characteristics of the traditional single-conductor SSPP and the double-conductor SSPP structure designed in this embodiment are numerically simulated through the eigenmode solver of CST Microwave Studio. The results are as Figure 5 shown. The dielectric substrate is selected as F4B material, with a relative dielectric constant of 3.5 and a loss tangent of 0.0027. The analysis of the dispersion curves shows that the dispersion curves of both structures are below the air line, showing a typical slow-wave effect. By adjusting the parameter of the inner groove depth h, the cut-off frequency of the structure can be effectively reduced, realizing flexible control of the dispersion characteristics. It is particularly worth noting that under the condition of the same physical size, the double-conductor SSPP structure exhibits more excellent dispersion control performance. This performance improvement is mainly reflected in the following aspects: First, the double-conductor structure has a stronger electromagnetic field localization effect, which can effectively improve the energy density; second, within the same operating frequency band, this structure can generate a larger phase change amount, showing significant potential for large scanning angles.

[0059] The double-conductor SSPPs show significant advantages in aspects such as dispersion control, anti-interference performance, miniaturization design, and beam scanning angle improvement, providing a new technical approach for antenna design.

[0060] As Figure 6As shown, as the inner width a parameter gradually increases and reaches 50% of the outer width p (the period of a unit structure in the SSPP structure), a fundamental transformation occurs in the geometric characteristics of the unit structure. This critical change in the size parameter not only leads to a significant reconstruction of the structural morphology, but more importantly, introduces a discontinuity feature in the electromagnetic field distribution. The generation of this discontinuity creates a key condition for the excitation of higher-order spatial harmonics, thus significantly changing the propagation characteristics of electromagnetic waves.

[0061] As Figure 7 shown, through a systematic analysis of the electromagnetic characteristics of the final unit structure of the SSPP structure (outer width p = 6.8 mm, inner width a = 3.5 mm, outer wall height d = 5.0 mm, and inner groove depth h = 2.4 mm), the complete dispersion relationship between its main mode and higher-order Bloch-Floquet harmonic modes was obtained. In the dispersion curve graph, the phase propagation constant of the free-space light wave marked by the solid black line is used as the reference baseline, and the entire dispersion characteristic region is clearly divided into two parts with completely different physical meanings: the upper blue region corresponds to the fast-wave propagation mode, whose phase velocity exceeds the speed of light in free space; the lower white region represents the slow-wave propagation characteristics, and the phase velocity is significantly lower than the speed of light. It is found that through the periodic modulation of the SSPP structure, the main mode in the slow-wave region can effectively excite multiple higher-order Bloch-Floquet harmonic modes. The mathematical expression of the Bloch-Floquet harmonic is as follows:

[0062] (1)

[0063] where represents the propagation constant of the main mode, represents the order index of the Bloch-Floquet harmonic, characterizes the modulation period. Since the modulation period is numerically exactly the same as the outer width of the unit structure, this simplifies the mathematical expression of the harmonic mode:

[0064] (2)

[0065] The main beam direction can be calculated through the phase propagation number , and the expression of the main beam deflection angle θ is as follows:

[0066] (3)

[0067] In the formula, represents the wave number in free space, and its value directly reflects the propagation characteristics of electromagnetic waves in a vacuum. Through Figure 7Analysis of the dispersion curve of the mid-harmonic mode can clearly observe the significant characteristics of the electromagnetic wave propagation behavior changing with frequency: when the operating frequency exceeds 13.0 GHz, the electromagnetic wave enters the fast-wave propagation region, and its phase velocity exceeds the speed of light in free space. At this time, the electromagnetic energy can be efficiently radiated into free space, forming an effective electromagnetic wave emission. In contrast, in the frequency range below 13.0 GHz, the harmonic mode is always in the slow-wave region, the phase velocity of the electromagnetic wave is significantly reduced, and the energy is effectively localized inside the double-conductor SSPPs structure, maintaining a stable slow-wave transmission characteristic. As the frequency continues to increase, the phase propagation constant β shows a non-linear variation law, and this change directly leads to a continuous deflection of the main beam propagation direction. The deflection angle θ of the main beam can be calculated by formula (3).

[0068] To deeply explore the electromagnetic radiation characteristics of the double-conductor SSPP structure, a full-wave simulation software was used to simulate its modulated structure, and the basic structure of the SSPP leaky-wave antenna shown in Figure 1 Figure 1 was obtained, including: a dielectric substrate 1, and a positive microstrip line 2 and a negative microstrip line 3 correspondingly arranged on the upper and lower surfaces of the dielectric substrate 1; the positive microstrip line 2 and the negative microstrip line 3 are respectively symmetric about the two ends of current transmission; the SSPP structure 4 in the middle section of the positive microstrip line 2 and the SSPP structure 4 in the middle section of the negative microstrip line 3 are arranged with the groove 401 openings facing each other;

[0069] This symmetric design not only simplifies the manufacturing process but also ensures the uniformity of the electromagnetic field distribution. In terms of material selection, an F4B dielectric substrate is used, with a relative permittivity εr = 3.5, a substrate thickness t = 0.5 mm, and a loss tangent tanδ = 0.0027. The top and bottom copper layers are printed on the F4B substrate, and the thickness of the copper layer is 0.018 mm. The first part of the leaky-wave antenna transmission is a rectangular 50-ohm microstrip line used as a feed port, with a length of L1, and the widths of the top and bottom feed lines are W1 and W2 respectively; the second part is a trapezoidal transition section, whose width gradually changes from W2 to W1 to ensure mode conversion and impedance matching; the third part is an SSPP structure, with a length of L3, to achieve leaky-wave radiation. Table 1 shows the specific parameter values of the antenna transmission structure.

[0070] Table 1 Specific parameter values of the antenna transmission structure

[0071] Parameter Value (mm) Parameter Value (mm) W 40 <![CDATA[L1]]> 5 <![CDATA[W1]]> 4 <![CDATA[L2]]> 15 <![CDATA[W2]]> 8 <![CDATA[L3]]> 243.2 r 4

[0072] Figure 8The S-parameters of the modulated dual-conductor SSPP structure are shown. It can be seen from the figure that above 13.0 GHz, the electromagnetic energy in the fast-wave region can radiate into free space, and the reflection coefficient S11 generally remains below -10.0 dB, showing excellent impedance matching characteristics. However, a significant increase in the reflection coefficient S11 is observed near 23.0 GHz, which is mainly attributed to the inherent open stopband effect of the structure. At the same time, the transmission coefficient S21 is below -20.0 dB throughout the test frequency band.

[0073] The above-designed dual-conductor SSPPs leaky-wave antenna exhibits an open stopband effect during scanning in the broadside direction. That is, when the main radiation direction approaches the broadside, strong standing wave phenomena will occur inside the antenna structure, resulting in blocked energy transmission. This effect is manifested in the antenna performance as a significant decrease in gain and a sharp increase in the reflection coefficient S11, seriously affecting the normal operating performance of the antenna.

[0074] To solve this problem, researchers have proposed various technical solutions. For example, using a quarter-wavelength matcher and a composite right / left-handed transmission line structure can achieve good impedance matching in a specific frequency band, but its complex implementation process and multi-parameter optimization requirements significantly increase the design difficulty and manufacturing cost. In contrast, in this embodiment, by introducing a smooth double semi-elliptical patch, the stopband effect is effectively weakened, thereby achieving a stable radiation gain in the broadside direction. Figure 2 The schematic diagram of the leaky-wave antenna structure optimized in this embodiment is shown. A double semi-elliptical metal patch 5 is added to the open end of the SSPP structure. The metal patches 5 are evenly arranged along the open end of the groove 401 of the SSPP structure 4. The double semi-elliptical structure is a closed structure formed by the intersection of two semi-elliptical curves. Based on the Floquet theory, the distance r between the intersections of the double semi-ellipses of the metal patch 5 is determined to be 4 mm, and the distance between the metal patches 5 is 8 mm. The distance d between the metal patches 5 is the distance between the midpoints of the distances r between the intersections of the two double semi-ellipses. The horizontal distance d between the metal patch 5 and the SSPP structure 4 on the same surface is 0.3 mm. Among them, the double semi-elliptical metal patches 5 added to the upper and lower surfaces of the dielectric substrate 1 are staggered, turning Figure 1 the symmetric antenna structure into Figure 2 an asymmetric antenna structure, weakening the stopband effect.

[0075] As Figure 9, as shown by the simulated S-parameters of the dual-conductor SSPP leaky-wave antenna calculated by CST simulation, within the wide frequency band range of 14.0 GHz - 34.0 GHz, the reflection coefficient S11 always remains below -10 dB, showing excellent impedance matching performance. Especially in the frequency band of 22.0 GHz - 25.0 GHz, that is, when the radiation direction of the antenna is close to broadside, the reflection coefficient S11 still performs well, fully verifying the matching effect of this design in the broadside direction.

[0076] Compared with the leaky-wave antenna of the basic design, the structure loaded with dual semi-elliptical patches significantly improves the S-parameter performance, achieving good impedance matching throughout the working frequency band and effectively overcoming the deficiencies of the original design. This result further proves the effectiveness of the dual semi-elliptical patches in suppressing the open stopband effect and improving the antenna performance.

[0077] Figure 10 The simulated radiation pattern of the final-designed SSPP leaky-wave antenna in the xoz plane is shown. It can be seen from the figure that within the frequency band of 14.0 GHz - 34.0 GHz, the designed dual-conductor SSPP leaky-wave antenna exhibits excellent beam scanning performance, and its main beam direction can be continuously adjusted within the wide angular range of -90° to +29°, achieving a large scanning angle coverage of 119°.

[0078] Figure 11 and Figure 12 are respectively the simulated radiation efficiency diagram and gain diagram of the final-designed SSPP leaky-wave antenna. It can be seen from the figure that within the frequency band of 14.0 GHz - 34.0 GHz, the radiation efficiency of the antenna is above 82% and the gain is greater than 10 dBi. At the same time, excellent gain stability is exhibited throughout the working frequency band, and the fluctuation range of the maximum gain and the minimum gain value relative to the average gain is controlled within 3 dBi. This gain consistency feature indicates that the antenna not only maintains a high radiation efficiency within the wide frequency band, but also has balanced performance at each frequency point. Notably, at the broadside frequency point of 24 GHz, the gain of the antenna is significantly better than the average gain level, which fully verifies the effectiveness of the dual semi-elliptical patch structure in suppressing and eliminating the stopband effect.

[0079] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0080] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a means for implementing the functions specified in the flow Figure 1 one or more flows and / or blocks Figure 1 or a means for implementing the functions specified in a block or multiple blocks.

[0081] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction means that implements the functions specified in the flow Figure 1 one or more flows and / or blocks Figure 1 or a means for implementing the functions specified in a block or multiple blocks.

[0082] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in the flow Figure 1 one or more flows and / or blocks Figure 1 or a means for implementing the functions specified in a block or multiple blocks.

[0083] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principles of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A SSPP leaky wave antenna, characterized in that: include: A dielectric substrate (1), and a positive microstrip line (2) and a negative microstrip line (3) arranged correspondingly on the upper and lower surfaces of the dielectric substrate (1); The positive microstrip line (2) and the negative microstrip line (3) are respectively symmetrical with respect to two ends of current transmission; The SSPP structure (4) of the middle section of the positive microstrip line (2) and the SSPP structure (4) of the middle section of the negative microstrip line (3) are arranged opposite to each other with the opening of the groove (401).

2. The SSPP leaky wave antenna according to claim 1, characterized in that: The anti-microstrip line (3) comprises a rectangular feeding structure (31) and a trapezoidal transition structure (32) between the two ends of the anti-microstrip line (3) and the middle section SSPP structure (4); current is transmitted from the rectangular feeding structure (31) at one end of the anti-microstrip line (3) to the SSPP structure (4) through the trapezoidal transition structure (32), thereby achieving impedance matching of the SSPP structure port.

3. The SSPP leaky wave antenna according to claim 2, characterized in that: The depths of the grooves (401) at both ends of the SSPP structure (4) decrease gradually along the two ends.

4. The SSPP leaky wave antenna according to claim 3, characterized in that: It also includes a plurality of metal patches, wherein the metal patches (5) are evenly arranged along the opening end of the groove (401) of the SSPP structure (4).

5. The SSPP leaky wave antenna according to claim 4, characterized in that: The metal patch (5) is a double semi-elliptical structure, which is a closed structure formed by the intersection of two semi-elliptical curves. The metal patch (5) is staggeredly arranged on the upper and lower surfaces of the dielectric substrate (1).

6. The SSPP leaky wave antenna according to claim 5, characterized in that: The dielectric substrate (1) is made of F4B material, the dielectric substrate (1) has a relative dielectric constant of 3.5, a thickness of 0.5 mm, and a loss tangent of 0.0027; the positive and negative microstrip lines are made of copper, and the thickness of the copper layer is 0.018 mm.

7. The SSPP leaky wave antenna according to claim 6, characterized in that: The width of the positive microstrip line (2) is 4 mm. The rectangular feeding structure (31) of the anti-microstrip line (3) is 8 mm wide and 5 mm long, the trapezoidal transition structure (32) is an isosceles trapezoid, the wide side of the rectangular feeding structure (31) is connected to the long base of the isosceles trapezoid, the height of the isosceles trapezoid is 15 mm, and the trapezoidal transition structure (32) transitions from the same width as the rectangular feeding structure (31) to the same width as the positive microstrip line (2).

8. The SSPP leaky wave antenna according to claim 7, characterized in that: The SSPP structure (4) is composed of a plurality of L-shaped structures connected end to end to form a periodic groove (401), and the groove (401) in the middle section of the SSPP structure (4) has a consistent depth; the L-shaped structural parameters of the groove (401) in the middle section of the SSPP structure (4) are: outer width p=6.8 mm, inner width a=3.5 mm, outer wall height d=5.0 mm and inner groove depth h=2.4 mm.

9. The SSPP leaky wave antenna according to claim 8, characterized in that: The distance r between the intersection points of the two semi-ellipses of the metal patch (5) is 4 mm, the distance between the metal patches (5) is 8 mm, the distance d between the metal patches (5) is the distance between the midpoints of the two semi-ellipses of the intersection point distance r, and the horizontal distance d between the metal patch (5) and the SSPP structure (4) on the same surface is 0.3 mm.

10. A design method for a SSPP leaky wave antenna, characterized in that: include: S1: Determine the design objectives of the SSPP leaky-wave antenna; S2: Determine the initial parameters of the unit structure constituting the SSPP structure according to the design goal of step S1; S3: According to the unit structure determined in step S2 and in combination with Floquet's theorem, the dispersion relation is deduced and the final parameters of the unit structure are determined; S4: According to the SSPP structure formed by the unit structure in step S3 and the Floquet theorem, the basic structure of the SSPP leaky wave antenna is determined. The basic structure comprises: a dielectric substrate (1), and a positive microstrip line (2) and a negative microstrip line (3) arranged correspondingly on the upper and lower surfaces of the dielectric substrate (1); The positive microstrip line (2) and the reverse microstrip line (3) are respectively symmetrical about the two ends of current transmission; the SSPP structure (4) in the middle section of the positive microstrip line (2) and the SSPP structure (4) in the middle section of the reverse microstrip line (3) are arranged opposite to each other with the opening of the groove (401); S5: According to the basic structure of step S4, combined with Floquet's theorem, a metal patch (5) with a double semi-elliptical structure is added to optimize the side-fire transmission of the basic structure, and the final SSPP leaky wave antenna is obtained.

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