Ultrahigh-scanning-rate leaky-wave antenna based on double-layer offset quasi-complementary SSPP

Abstract

The invention discloses an ultrahigh-scanning-rate leaky-wave antenna based on double-layer offset quasi-complementary SSPP. The antenna comprises a dielectric substrate, double-layer single-side offset quasi-complementary SSPP structures on the upper surface and the lower surface of the dielectric substrate, a double-layer mode conversion structure and a dielectric substrate top layer periodic modulation branch knot. Wherein the longitudinal symmetry axis of the dielectric substrate top layer single-side strip SSPP unit and the longitudinal symmetry axis of the dielectric substrate bottom layer single-side slot SSPP unit are relatively offset, and a double-layer single-side offset quasi-complementary SSPP unit is jointly formed; the double-layer mode conversion structure is composed of a trapezoidal gradual change structure on the top layer of the dielectric substrate and a periodic gradual change slotting structure on the bottom layer of the dielectric substrate; and the dielectric substrate top layer periodic modulation branch knot is formed by compounding a rectangular structure and a semicircular structure loaded at the tail end of the rectangular structure, and is positioned on the opposite side of the top layer single-side strip SSPP structure. The wide-angle scanning ultra-narrow band-pass filter has the advantages of wide-angle scanning, ultra-narrow working bandwidth, ultra-high beam scanning rate and open stop-band suppression, and has very high practical potential in the fields of radar, imaging and the like.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP. Background Art

[0002] Frequency-scanning antennas play a crucial role in applications such as radar and imaging. Leaky-wave antennas, as a type of frequency-scanning antenna, offer unique beam-scanning performance, high gain, and low cost. Their beam-scanning rate is defined as the ratio of the beam-scanning range to the operating bandwidth. High-scanning-rate leaky-wave antennas can achieve a large scanning range within a narrow frequency band, conserving spectrum resources and reducing the sampling pressure on imaging systems. Therefore, designing high-scanning-rate leaky-wave antennas is crucial for practical applications.

[0003] Currently, only a few proposals have been made to increase the scan rate of leaky-wave antennas, primarily focusing on highly dispersive structures. This sensitivity of the phase constant to frequency variations facilitates the design of high-scan-rate leaky-wave antennas. To further reduce the complexity of front-end hardware, traditional leaky-wave antennas with low scan rates are no longer sufficient, and leaky-wave antennas with ultra-high scan rates are urgently needed. However, achieving high scan rates often results in a degradation of the antenna's radiation efficiency and gain. Therefore, innovative antenna structure designs are urgently needed to improve these efficiency and gain at high scan rates. In traditional leaky-wave antenna designs, the inherent symmetry of the structure often leads to the inevitable appearance of open stopbands at the Brillouin zone boundaries, resulting in directional distortion of the main beam near the normal and reduced radiation efficiency. This open stopband effect limits the antenna's performance consistency across a wide range of scan angles, making it particularly prominent in applications requiring high scan rates and wide-angle beam scanning. Therefore, effectively suppressing the open stopband and improving beam continuity and radiation stability have become widely recognized design challenges in leaky-wave antenna design.

[0004] To address the aforementioned technical challenges, the present invention designs a novel, innovative double-layer offset quasi-complementary surface plasmon polaritons (SSPP) leaky-wave antenna with ultra-high scan rate, based on an artificial surface plasmon polariton (SSPP) transmission line structure. The leaky-wave antenna proposed in this invention offers advantages such as a wide beam scanning range, an extremely narrow operating bandwidth, and an ultra-high scan rate, while effectively suppressing the open stopband effect. It is particularly suitable for radar, imaging, and other high-performance frequency scanning systems. Its excellent spectrum utilization efficiency and ability to reduce sampling burden give it broad engineering application prospects in areas such as high-density information acquisition and real-time imaging. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and provide an ultra-high scan rate leaky wave antenna based on a double-layer offset quasi-complementary SSPP, which can achieve a wide scanning range within an extremely narrow frequency band, improve radiation efficiency and gain while having an ultra-high scan rate, and can suppress open stopbands.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP structure, comprising: a dielectric substrate, a double-layer unilaterally offset quasi-complementary SSPP structure above and below the dielectric substrate, a double-layer mode conversion structure, and a periodically modulated branch on the top layer of the dielectric substrate. The longitudinal symmetry axes of the single-sided strip SSPP unit on the top layer of the dielectric substrate and the single-sided slot SSPP unit on the bottom layer of the dielectric substrate are relatively offset, forming a double-layer unilaterally offset quasi-complementary SSPP unit. The double-layer mode conversion structure is composed of a trapezoidal gradient structure on the top layer of the dielectric substrate and a periodically gradient slot structure on the bottom layer of the dielectric substrate. The periodically modulated branch on the top layer of the dielectric substrate is composed of a rectangular structure and a semicircular structure loaded at its end, and is located opposite the single-sided strip SSPP structure on the top layer.

[0007] Furthermore, the longitudinal symmetry axis of the single-sided strip on the top layer of the dielectric substrate is offset by a certain amount relative to the longitudinal symmetry axis of the single-sided slot SSPP unit on the bottom layer of the dielectric substrate to form a double-layer offset structure.

[0008] Furthermore, the width of the strip on one side of the top dielectric substrate is smaller than the width of the slot on one side of the bottom dielectric substrate, and the length of the strip on one side of the top dielectric substrate is smaller than the length of the slot on one side of the bottom dielectric substrate, so as to form a double-layer quasi-complementary structure.

[0009] Furthermore, the arrangement period of the single-sided strips SSPP on the top layer of the dielectric substrate is the same as the arrangement period of the single-sided slots SSPP on the bottom layer of the dielectric substrate.

[0010] Furthermore, the single-sided strip SSPP structure on the top layer of the dielectric substrate and the single-sided slot SSPP structure on the bottom layer of the dielectric substrate are on the same side, and the single-sided strip SSPP structure on the top layer of the dielectric substrate and the periodically modulated metal branches on the top layer of the dielectric substrate are on opposite sides.

[0011] Furthermore, the end of the periodically modulated metal branch on the top layer of the dielectric substrate is loaded with a semicircular patch. The semicircular patch at the end changes the geometric curvature of the end of the branch, thereby changing the path of the current, enhancing the disturbance of the surface electromagnetic waves, and leaking more abundant electromagnetic wave energy to improve the radiation efficiency and gain of the antenna.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] one, Figure 8The leaky-wave antenna's E-plane far-field patterns at different frequencies are shown. It clearly demonstrates continuous beam scanning from -63° to +32° within the ultra-narrow frequency band of 8.28 GHz to 8.62 GHz (relative bandwidth of 4%), with a scanning range of 95° and a beam scanning rate of 23.75° / %. Among existing SSPP-based leaky-wave antennas, the proposed antenna has the highest beam scanning rate. Therefore, it has broad engineering application prospects in radar, imaging, and other high-performance frequency scanning systems.

[0014] two, Figure 9 The S parameters of the leaky wave antenna are shown. In the beam scanning frequency band of 8.28GHz to 8.62GHz, the reflection coefficient S 11 and the transmission coefficient S 21 Both are less than -10dB, indicating that when the antenna is working, the reflected energy and the transmitted energy are very small, achieving efficient leakage of electromagnetic waves into space.

[0015] 3. Figure 10 The gain and radiation efficiency graphs of the leaky-wave antenna are shown. Due to the semicircular patch design at the end of the top periodically modulated metal branch, this structural design effectively improves the antenna's radiation efficiency and gain, although achieving a high scan rate often comes at the expense of radiation efficiency. The resulting peak gain is 10.2dBi and the peak radiation efficiency is 33.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The three-view diagram of the overall structure of an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP in an example of the present invention;

[0017] Figure 2 for Figure 1 A partial enlarged schematic diagram;

[0018] Figure 3 for Figure 1 A partial enlarged schematic diagram of B in the middle;

[0019] Figure 4 for Figure 1 A partial enlarged schematic diagram of center C;

[0020] Figure 5 Schematic diagrams of the upper and lower surfaces of a double-layer offset quasi-complementary unit structure of an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP in an example of the present invention;

[0021] Figure 6 A perspective view of a double-layer offset quasi-complementary unit structure of an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP in an example of the present invention;

[0022] Figure 7 Schematic diagram of a unit dispersion curve of an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP in an example of the present invention;

[0023] Figure 8 The E-plane far-field radiation pattern at different frequencies of an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP in an example of the present invention;

[0024] Figure 9 Schematic diagram of S parameters of an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP in an example of the present invention;

[0025] Figure 10 Graph showing the gain and radiation efficiency of an ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP in an example of the present invention. DETAILED DESCRIPTION

[0026] The specific embodiments described herein are only used to explain the technical solutions of the present invention and are intended to help understand the principles and applications of the present invention, and are not intended to limit the scope of protection of the present invention.

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] An ultra-high scan rate leaky wave antenna based on a double-layer offset quasi-complementary SSPP structure, the overall three-view drawing is as follows Figure 1 As shown. The antenna uses Rogers 5880 as the dielectric substrate (1). The size of the dielectric substrate (1) is 301mm*40mm*0.508mm, the dielectric constant is 2.2, and the loss tangent value is 0.0009. The top structure (2) of the dielectric substrate mainly includes the following parts: a pair of 50 ohm microstrip feeding structures (21) for inputting signals; Figure 2 A pair of trapezoidal gradient mode conversion structures (22) shown in the figure can convert the quasi-TEM mode of the microstrip line into the SSPP waveguide mode and achieve good impedance matching, thereby supporting the effective propagation of electromagnetic waves in the SSPP structure; a group of periodically arranged single-sided subwavelength strips (23) are used to form a single-sided strip-type SSPP on the top layer; a group of periodically arranged opposite-side modulated metal branches (24) are used to disturb the surface electromagnetic waves in the SSPP, thereby achieving effective radiation of energy into free space; as shown in FIG. Figure 4As shown, the top periodic modulation metal branch (24) and the top single-sided strip SSPP structure (23) are loaded on both sides of the main feeder respectively. The top opposite side modulation metal branch (24) is composed of a rectangular patch (241) and a semicircular patch (242) loaded at the end, which can effectively improve the radiation efficiency and gain of the antenna. In the bottom structure (3) of the dielectric substrate, it mainly includes the following parts: Figure 3 The two groups of gradient slot transition structures (31) are used to achieve mode matching and impedance matching; a group of periodically arranged single-sided sub-wavelength slots (32) forms a single-sided slot-type SSPP at the bottom layer.

[0029] Specifically, such as Figure 5 As shown in Figure 2, the double-layer offset quasi-complementary unit structure is composed of a top-layer single-side strip unit structure and a bottom-layer single-side slot unit structure. The width of the top-layer single-side strip is denoted as w1, and the width of the bottom-layer single-side slot is denoted as w2. Figure 6 The perspective view of the double-layer offset quasi-complementary unit structure is shown in FIG. , wherein the two dot-dashed lines represent the longitudinal symmetry axis of the single-sided strip on the top layer of the dielectric substrate and the longitudinal symmetry axis of the single-sided slot on the bottom layer of the dielectric substrate, respectively. The offset distance between the two longitudinal symmetry axes is recorded as s1.

[0030] Specifically, such as Figure 7 The schematic diagram of the unit dispersion curve shows that s1 = 0 mm and w1 = 1 mm corresponds to a double-layer complementary structure, s1 = 0 mm and w1 = 0.5 mm corresponds to an unshifted double-layer quasi-complementary structure, and s1 = 0.25 mm and w1 = 0.5 mm corresponds to a double-layer offset quasi-complementary structure. Comparing the dispersion curves, we can observe that the dispersion curves of the double-layer complementary structure and the unshifted double-layer quasi-complementary structure are essentially identical. However, the double-layer offset quasi-complementary structure has a lower cutoff frequency and a lower curve slope than the other two unit structures, demonstrating significantly stronger slow-wave characteristics. This is because the offset structure breaks the symmetry of the upper and lower structures, causing the current distribution to change, thereby enhancing the coupling effect between the upper and lower metals, causing electromagnetic waves to propagate more slowly within the structure. This offset quasi-complementary unit structure is key to the design of ultra-high scan rate leaky-wave antennas.

[0031] Specifically, Figure 8 The leaky-wave antenna's E-plane far-field patterns at different frequencies are displayed. It clearly demonstrates that the antenna achieves continuous beam scanning from -63° to +32° within an ultra-narrow frequency band of 8.28 GHz to 8.62 GHz (relative bandwidth of 4%), with a scanning range of 95° and a beam scanning rate of 23.75° / %. Among existing SSPP-based leaky-wave antennas, the antenna proposed in this invention has the highest beam scanning rate. Figure 9 The S parameters of the leaky wave antenna are shown. In the beam scanning frequency band of 8.28GHz to 8.62GHz, the reflection coefficient S11 and the transmission coefficient S 21 Both are less than -10dB, indicating that when the antenna is working, the reflected energy and the transmitted energy are very small, achieving efficient leakage of electromagnetic waves into space.

[0032] Specifically, such as Figure 10 The gain and radiation efficiency diagrams of the leaky-wave antenna are shown. Due to the structural design of the semicircular patch at the end of the top periodically modulated metal branch, although the leaky-wave antenna achieves a high scan rate at the expense of radiation efficiency, this structural design effectively improves the antenna's radiation efficiency and gain. The semicircular patch at the end changes the geometric curvature of the branch end, thereby altering the current path, enhancing the perturbation of the surface electromagnetic waves, leaking more abundant electromagnetic wave energy, and thus improving the antenna's radiation efficiency and gain. The final peak gain is 10.2dBi, and the peak radiation efficiency is 33.5%.

[0033] Specifically, the antenna of the embodiment of the present invention is designed and optimized based on the electromagnetic simulation software CST. The relevant dimensions of the leaky-wave antenna structure are shown in Table 1.

[0034] Table 1 Leaky-wave antenna related dimensions

[0035]

[0036] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP, characterized by: The antenna consists of a dielectric substrate, a double-layer unilaterally offset quasi-complementary SSPP structure on the upper and lower sides of the dielectric substrate, a double-layer mode conversion structure, and periodic modulation branches on the top layer of the dielectric substrate. The longitudinal symmetry axes of the single-sided strip SSPP unit on the top layer of the dielectric substrate and the single-sided slot SSPP unit on the bottom layer of the dielectric substrate are relatively offset, forming a double-layer unilaterally offset quasi-complementary SSPP unit. The mode conversion structure is composed of a trapezoidal gradient structure on the top layer of the dielectric substrate and a periodic gradient slot structure on the bottom layer of the dielectric substrate. The periodic modulation branches on the top layer of the dielectric substrate are composed of a rectangular structure and a semicircular structure loaded at its end, and are located opposite the single-sided strip SSPP structure on the top layer.

2. The ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP according to claim 1, characterized in that: The longitudinal symmetry axis of the single-sided strip SSPP unit on the top layer of the dielectric substrate is offset by a certain amount relative to the longitudinal symmetry axis of the single-sided slot SSPP unit on the bottom layer of the dielectric substrate to form a double-layer offset structure.

3. The ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP according to claim 1, characterized in that: The width of the strip on one side of the top dielectric substrate is smaller than the width of the slot on one side of the bottom dielectric substrate, and the length of the strip on one side of the top dielectric substrate is smaller than the length of the slot on one side of the bottom dielectric substrate, so as to form a double-layer quasi-complementary structure.

4. The ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP according to claim 1, characterized in that: The arrangement period of the single-sided strips SSPP on the top layer of the dielectric substrate is the same as the arrangement period of the single-sided slots SSPP on the bottom layer of the dielectric substrate.

5. The ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP according to claim 1, characterized in that: The single-sided strip SSPP structure on the top layer of the dielectric substrate and the single-sided slot SSPP structure on the bottom layer of the dielectric substrate are on the same side, and the single-sided strip SSPP structure on the top layer of the dielectric substrate and the periodically modulated metal branches on the top layer of the dielectric substrate are on opposite sides.

6. The ultra-high scan rate leaky-wave antenna based on a double-layer offset quasi-complementary SSPP according to claim 1, characterized in that: The end of the periodically modulated metal branch on the top layer of the dielectric substrate is loaded with a semicircular patch. The semicircular patch at the end changes the geometric curvature of the branch end, thereby changing the path of the current, enhancing the disturbance of the surface electromagnetic waves, and leaking more abundant electromagnetic wave energy to improve the radiation efficiency and gain of the antenna.

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