Full-space scanning leaky-wave antenna based on double-cycle SSPP

Abstract

The invention discloses a full-space scanning leaky-wave antenna based on double-cycle SSPP. The antenna is composed of a dielectric substrate, a dielectric substrate top layer structure and a dielectric substrate bottom layer structure. The dielectric substrate top layer structure comprises an SSPP module with a period of p1, a plurality of spine type modulation modules and a top layer mode matching module; the bottom layer structure of the dielectric substrate comprises an SSPP module with a p2 period, a plurality of spine type modulation modules and a bottom layer mode matching module; the period p1 of the dielectric substrate top layer SSPP module is half of the period p2 of the dielectric substrate bottom layer SSPP module, so that a double-layer double-period SSPP composite structure is formed; the spine type modulation module disturbs surface electromagnetic waves of the SSPP to promote electromagnetic wave energy to leak to the air; the outer side of the mode matching module is electrically connected with the feed end, and the inner side of the mode matching module is electrically connected with the SSPP structure. The method has the characteristics of full-space beam scanning, open stop-band suppression and the like, and has great application potential in the fields of radar, imaging and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a full-space scanning leaky-wave antenna based on a double-periodic SSPP. Background Art

[0002] As radar, communications, and other systems continue to increase their requirements for beam scanning capabilities, antenna structures capable of achieving wide-range beam scanning have received widespread attention. Frequency-scanning leaky-wave antennas have become an effective alternative to phased array antennas due to their simple structure and low cost. However, among existing leaky-wave antennas, few full-space scanning leaky-wave antenna solutions have been proposed, and traditional leaky-wave antennas typically have open stopbands. Periodic leaky-wave antennas can achieve beam scanning in the front-to-back space by utilizing the negative first spatial harmonic. However, when the beam is scanned in the broadside direction, the reflected waves generated by each leaky-wave unit will superimpose in phase with each other, resulting in a significant increase in the reflection coefficient at the antenna input. At this point, most of the energy cannot enter the antenna, resulting in a serious gain reduction problem in the broadside direction, which in turn hinders the continuous scanning function of the beam in the front-to-back space. Developing new open stopband suppression methods is of great significance for improving the performance of leaky-wave antennas.

[0003] Artificial surface plasmons (SSPPs) are a type of electromagnetic surface wave that propagates in a highly localized manner on the subwavelength scale. By periodically slotting or loading subwavelength structures on the metal surface, it is possible to confine the surface electromagnetic waves and achieve good tunability in dispersion characteristics. Therefore, SSPPs are widely used in slow-wave devices, couplers, antennas, sensors, and other fields. In antenna design, the fundamental mode of SSPP conduction itself belongs to the slow-wave mode. The electromagnetic wave energy is mainly confined to the surface of the structure and is difficult to radiate directly into free space. In order to achieve effective spatial radiation, it is usually necessary to excite its high-order spatial harmonics and convert the original slow-wave mode into a radiative fast-wave mode, thereby achieving energy leakage.

[0004] To address these technical challenges, this paper designs a full-space scanning leaky-wave antenna based on a dual-periodic SSPP transmission line structure. This leaky-wave antenna exhibits full-space beam scanning capabilities and proposes a novel open stopband suppression scheme for the dual-periodic SSPP, providing a new technical approach and concept for the design of high-performance leaky-wave antennas. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies of the above-mentioned prior art and provide a full-space scanning leaky-wave antenna based on a dual-periodic SSPP, which can realize full-space beam scanning and suppress open stopband.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a full-space scanning leaky-wave antenna based on a dual-periodic SSPP structure, comprising: a dielectric substrate, a top-layer dielectric substrate structure, and a bottom-layer dielectric substrate structure. The top-layer dielectric substrate structure comprises an SSPP module with a period of p1, a plurality of spike-type modulation modules, and a top-layer mode matching module; the bottom-layer dielectric substrate structure comprises an SSPP module with a period of p2, a plurality of spike-type modulation modules, and a bottom-layer mode matching module. The period p1 of the top-layer SSPP module is half the period p2 of the bottom-layer SSPP module, forming a double-layer dual-periodic SSPP structure. The spike-type modulation module causes electromagnetic wave energy to leak into the air by disturbing the surface electromagnetic waves of the SSPP. The mode matching module is electrically connected to the feed terminal on the outside and to the SSPP structure on the inside.

[0007] Furthermore, the top mode matching module and the top mode matching module are composed of a gradual transition structure, which can convert the quasi-TEM mode of the microstrip line into the transmission mode of the SSPP, and at the same time have the function of impedance matching.

[0008] Furthermore, the spike-shaped modulation modules of the upper and lower layers are respectively placed on opposite sides of the double-layer SSPP to disturb the surface electromagnetic waves of the SSPP, thereby causing the surface electromagnetic wave energy to leak into the air.

[0009] Furthermore, the double-layer double-period SSPP composite unit includes a pair of branches on the top layer of the dielectric substrate and a branch on the bottom layer of the dielectric substrate. The pair of branches on the top layer of the dielectric substrate form a π-shaped branch, and the branch on the bottom layer of the dielectric substrate forms a T-shaped branch. The π-shaped branch unit and the T-shaped branch unit are placed in a mosaic and complementary form.

[0010] Furthermore, the two ends of the top structure of the dielectric substrate are electrically connected to the metal inner core of the SMA connector, and the two ends of the bottom structure of the dielectric substrate are electrically connected to the metal outer pins of the SMA connector. In the upper and lower SSPP current transmission paths, at any identical position, charges with opposite polarities are equivalent to an ideal electric wall, providing the leaky wave antenna with end-to-end radiation capability, thereby realizing the function of full-space scanning.

[0011] Furthermore, the SSPP module on the top layer of the dielectric substrate generates a beam in one direction, and the SSPP module on the bottom layer of the dielectric substrate generates a beam in another direction. When the two radiation beams are symmetrically distributed on both sides of the leaky wave antenna in the side direction, the synthesized total beam will compensate for the side radiation energy to suppress the open stopband effect of the leaky wave antenna.

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

[0013] one, Figure 4A schematic diagram of beam synthesis is shown. The SSPP module with a top-level period of p1 generates beam a, and the SSPP module with a bottom-level period of p2 generates beam b. In the far field of the antenna, beam a and beam b are synthesized into beam c, which can effectively compensate for the side radiation performance of the leaky-wave antenna, thereby realizing the function of open stopband suppression.

[0014] two, Figure 5 The E-plane far-field patterns of the leaky-wave antenna at different frequencies are displayed. It can be clearly seen that the leaky-wave antenna achieves dual-beam full-space scanning from -90° to +90° in the frequency band of 6.9GHz to 9.8GHz, with a relative bandwidth of 34.73% and a beam scanning rate of 5.2° / %. Figure 6 The S parameters of the leaky wave antenna are shown. In the 6.9GHz to 9.8GHz frequency band of beam scanning, the reflection coefficient S 11 Less than -10dB, indicating that the open stopband of the leaky wave antenna is effectively suppressed. 21 It is also relatively small within the entire operating frequency band, indicating that the electromagnetic waves are efficiently leaked into space when the antenna is working.

[0015] 3. Figure 7 The gain and radiation efficiency diagram of the leaky-wave antenna are shown, with a peak gain of 10.9dBi and a peak radiation efficiency of 78%. The leaky-wave antenna provided by the present invention has the characteristics of full-space beam scanning, relatively flat beam gain variation, simultaneous suppression of open stopband, high gain, low profile, and relatively small size. It is suitable for fields such as radar and imaging systems with large-range beam scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The three-view diagram of the overall structure of a full-space scanning leaky-wave antenna based on a dual-periodic SSPP in an example of the present invention;

[0017] Figure 2 A perspective view of a double-layer double-periodic SSPP composite structure unit of a full-space scanning leaky wave antenna based on a double-periodic SSPP in an example of the present invention;

[0018] Figure 3 for Figure 1 Partial perspective view of center A;

[0019] Figure 4 Schematic diagram of beam synthesis of a full-space scanning leaky-wave antenna based on a dual-periodic SSPP in an example of the present invention;

[0020] Figure 5 The E-plane far-field radiation pattern of a full-space scanning leaky-wave antenna based on a double-periodic SSPP at different frequencies in an example of the present invention;

[0021] Figure 6Schematic diagram of S parameters of a full-space scanning leaky-wave antenna based on a double-periodic SSPP in an example of the present invention;

[0022] Figure 7 Graphs showing the gain and radiation efficiency of a full-space scanning leaky-wave antenna based on a dual-periodic SSPP in an example of the present invention. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] A full-space scanning leaky wave antenna based on a double-periodic SSPP, the overall three-view image is as follows Figure 1 The antenna uses Rogers RO4003C as a dielectric substrate (1), the dielectric substrate (1) has a size of 260mm*40mm*1.524mm, a dielectric constant of 3.55, and a loss tangent value of 0.0027, and the upper and lower surfaces of the dielectric substrate (1) are a dielectric substrate top structure (2) and a dielectric substrate bottom structure (3), respectively.

[0026] Specifically, the top microstrip side-feed structure (21) is located at both ends of the dielectric substrate top structure (2), is externally connected to the inner core of a 50-ohm SMA connector, and is internally connected to a top mode matching module (22). The top mode matching module (22) converts the quasi-TEM mode of the microstrip line into an SSPP transmission mode and simultaneously performs impedance matching on the leaky wave antenna. The top SSPP module (24) is formed by a group of sub-wavelength single-sided short branches arranged periodically, with an arrangement period of p1. Due to its high-dispersion slow-wave characteristics, it can bind electromagnetic waves to the SSPP surface. On the opposite side of the top SSPP module (24), a group of spike-shaped structures (23) are arranged to excite the high-order harmonics of the top SSPP module (24). The high-order harmonics working in the fast-wave region can leak electromagnetic waves into space.

[0027] Specifically, the bottom microstrip grounding structure (31) is located at both ends of the dielectric substrate bottom structure (3) and is externally connected to the external pins of a 50-ohm SMA connector. The bottom SSPP module (32) is formed by a group of sub-wavelength single-sided short branches arranged periodically, with an arrangement period of p2. On the opposite side of the bottom SSPP module (24), a group of spike-shaped structures (33) are arranged to excite the high-order harmonics of the top and bottom SSPP modules (32). The high-order harmonics operating in the fast wave region can leak electromagnetic waves into space.

[0028] Specifically, such as Figure 2 As shown, the double-layer double-periodic SSPP composite structure unit includes a pair of branches on the top layer of the dielectric substrate and a branch on the bottom layer of the dielectric substrate. The pair of branches on the top layer of the dielectric substrate form a π-shaped branch, and the branch on the bottom layer of the dielectric substrate forms a T-shaped branch. The π-shaped branch unit and the T-shaped branch unit are placed in a mosaic and complementary manner.

[0029] Specifically, in the current transmission paths of the top SSPP module (24) and the bottom SSPP module (32), at any identical position, the charges of the upper and lower layers with opposite polarities are equivalent to an ideal electric wall, providing the leaky wave antenna with the ability of end-to-end radiation, thereby realizing the function of full-space scanning.

[0030] Specifically, such as Figure 3 As shown in the partial perspective view of FIG, the period of the top SSPP module (32) is half of the arrangement period of the bottom SSPP module (24), forming a non-continuous mosaic complementary structure, as shown in FIG. Figure 4 As shown in the beam synthesis diagram, the top SSPP module (24) generates a radiation beam a in one direction, and the bottom SSPP module (32) generates a radiation beam b in another direction. After the electromagnetic waves are superimposed in the far field of the antenna, beam a and beam b can be synthesized into beam c, which can effectively compensate for the side radiation performance of the leaky wave antenna, thereby realizing the function of open stopband suppression.

[0031] 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.

[0032] Table 1 Leaky-wave antenna related dimensions

[0033]

[0034] In this embodiment, the leaky wave antenna achieves dual-beam full-space scanning from -90° to +90° in the frequency band of 6.9 GHz to 9.8 GHz, with a relative bandwidth of 34.73% and a beam scanning rate of 5.2° / %. In the beam scanning frequency band of 6.9 GHz to 9.8 GHz, the reflection coefficient S 11Less than -10dB, indicating that the leaky wave antenna open stopband is effectively suppressed. 21 The leaky-wave antenna has a relatively low gain across the entire operating frequency band, demonstrating efficient leakage of electromagnetic waves into space during operation. Furthermore, the antenna achieves a peak gain of 10.9 dBi and a peak radiation efficiency of 78%. The leaky-wave antenna provided by the present invention features full-space beam scanning, relatively flat beam gain variation, simultaneous suppression of open stopbands, high gain, a low profile, and a relatively small size. It is suitable for applications in wide-range beam scanning radars and imaging systems.

[0035] 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. A full-space scanning leaky-wave antenna based on a dual-periodic SSPP, characterized by: The antenna is composed of a dielectric substrate, a top structure of the dielectric substrate, and a bottom structure of the dielectric substrate. The top structure of the dielectric substrate includes an SSPP module with a period of p1, several spike-type modulation modules, and a top mode matching module. The bottom structure of the dielectric substrate includes an SSPP module with a period of p2, several spike-type modulation modules, and a bottom mode matching module. The period p1 of the SSPP module on the top of the dielectric substrate is half the period p2 of the SSPP module on the bottom of the dielectric substrate, forming a double-layer double-period SSPP composite structure. The spike-type modulation module causes the electromagnetic wave energy to leak into the air by disturbing the surface electromagnetic waves of the SSPP. The outer side of the mode matching module is electrically connected to the feeding end, and the inner side is electrically connected to the SSPP structure.

2. The full-space scanning leaky-wave antenna based on a dual-periodic SSPP according to claim 1, characterized in that: The spike-shaped modulation modules in the upper and lower layers are respectively placed on opposite sides of the double-layer SSPP to disturb the surface electromagnetic waves of the SSPP and cause the surface electromagnetic wave energy to leak into the air.

3. The full-space scanning leaky-wave antenna based on a dual-periodic SSPP according to claim 1, characterized in that: The unit of the double-layer double-periodic SSPP composite structure includes a pair of branches on the top layer of the dielectric substrate and one branch on the bottom layer of the dielectric substrate. The pair of branches on the top layer of the dielectric substrate form a π-shaped branch, and the one branch on the bottom layer of the dielectric substrate forms a T-shaped branch. The π-shaped branch and the T-shaped branch are placed in a complementary mosaic form.

4. The full-space scanning leaky-wave antenna based on a double-periodic SSPP according to claims 1 to 3, characterized in that: The SSPP module on the top layer of the dielectric substrate generates a beam in one direction, while the SSPP module on the bottom layer of the dielectric substrate generates a beam in another direction. When the two radiation beams are symmetrically distributed on both sides of the leaky-wave antenna in the side direction, the synthesized total beam compensates for the side-wise radiation energy, thereby suppressing the open stopband effect of the leaky-wave antenna.

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