Broadband millimeter wave leaky-wave antenna based on substrate integrated coaxial line and design method

Abstract

The application discloses a wideband millimeter wave leaky-wave antenna based on a substrate integrated coaxial line and a design method, and relates to the technical field of electronic communication.The antenna comprises, from top to bottom, a two-dimensional metal metasurface layer, a metasurface dielectric substrate part, a substrate integrated coaxial waveguide top layer slot layer, a substrate integrated coaxial waveguide upper layer dielectric layer, an adhesive layer, a substrate integrated coaxial waveguide inner conductor layer, a substrate integrated coaxial waveguide lower layer dielectric layer and a metal ground plate; and a first port and a second port arranged at two ends of the inner conductor layer.The application realizes enhanced radiation, improves the radiation efficiency of the leaky-wave antenna, and meets the demand of a miniaturized communication system.

Description

Technical Field

[0001] This invention relates to the field of electronic communication technology, and in particular to a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line and its design method. Background Technology

[0002] Leaky wave antennas (LWAs), as classic traveling wave structures, are highly favored due to their high directivity, wide bandwidth, and ease of integration. With the development of wireless communication technology, an increasing number of waveguide structures (such as rectangular waveguides, coaxial cables, substrate integrated waveguides (SIW), half-mode SIW (HMSIW), substrate integrated coaxial lines (SICL), half-mode substrate integrated coaxial lines, gap waveguides, microstrip lines, parallel plates, and artificial surface plasmon polaritons) are being used in the development and application of leaky wave antennas in the microwave and millimeter-wave fields. Typically, the radiation of LWAs is generated by the leakage of traveling waves propagating within the waveguide structure.

[0003] Recently, an attractive transmission line—substrate integrated coaxial cable (SICL)—with its shielded and non-dispersive structure, has been proven over wide bandwidths and applied to various passive components such as couplers, filters, and antennas. As a two-conductor transmission line, SICL can transmit TEM waves and offers advantages such as low channel loss, low delay, low crosstalk, strong electromagnetic interference immunity, and ease of fabrication and integration. Combining the advantages of SIW and coaxial cables, it shows promising development and application prospects in microwave and millimeter-wave devices.

[0004] For broadband millimeter-wave leaky antennas, periodic leaky antennas often fail to function properly when scanning towards the side-firing direction due to strong reflections and poor impedance matching characteristics, frequently exhibiting open stopband (OSB) phenomena that limit the antenna's bandwidth. Over the past few decades, researchers have proposed a series of methods to address the OSB problem, enabling leaky antennas to achieve wider bandwidth and broader frequency scanning capabilities. The main methods for suppressing OSB include additional slot reflection cancellation matching, short-circuit hole matching, graded half-wavelength transmission lines, and left-right composite transmission lines (CRLH-TL).

[0005] Generally, most periodic leaky-wave antennas possess the inherent characteristic of single-beam frequency scanning and are used in many systems such as radar sensing, nuclear magnetic resonance technology, and vehicle communication. Furthermore, there is an urgent need for applications requiring simultaneous multi-target detection, such as automotive Doppler radar sensors, angle diversity performance, enhanced synthetic aperture radar (SAR) system capabilities, and dual-beam broadband antennas capable of radiating two or more main beams.

[0006] Therefore, proposing a broadband millimeter-wave leaky antenna based on substrate-integrated coaxial line and its design method to solve the difficulties existing in the prior art is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line and a design method thereof. It can suppress open stopband and improve radiation efficiency by using a combination of gradient slots and metasurfaces. It also achieves high-performance dual-beam radiation characteristics in both vertical and horizontal space by using dual leaky sources and dual metasurfaces.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line includes: a coaxial feed section, a substrate-integrated coaxial line waveguide section, and a metasurface layer section with a dielectric substrate.

[0010] The coaxial feed section is located on both sides of the substrate-integrated coaxial waveguide section; the metasurface layer section with dielectric substrate is located on the upper surface of the substrate-integrated coaxial waveguide section.

[0011] The coaxial power supply section includes:

[0012] First port and second port;

[0013] The first port and the second port are located at both ends of the inner conductor layer;

[0014] The metasurface layer portion with dielectric substrate includes:

[0015] A two-dimensional metal metasurface layer and a dielectric substrate portion of the metasurface, wherein the two-dimensional metal metasurface layer is disposed on the dielectric substrate portion of the metasurface;

[0016] The substrate-integrated coaxial waveguide section includes, from top to bottom, the following components:

[0017] The substrate-integrated coaxial waveguide consists of a top slot layer, an upper dielectric layer, an adhesive layer, an inner conductor layer, a lower dielectric layer, and a metal ground plane.

[0018] Optionally, each layer of the aforementioned broadband millimeter-wave leaky antenna may be provided with two rows of air holes for mounting metal screws to fix the structure.

[0019] Optionally, the aforementioned broadband millimeter-wave leaky antenna may have periodic slots etched simultaneously on the top layer of the substrate-integrated coaxial waveguide and the metal ground plane, and a metasurface attached to the upper and lower radiating surfaces to obtain broadband dual-beam radiation.

[0020] A design method for a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line, used to design a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line as described above, includes the following steps:

[0021] S1. Data determination steps: Determine the operating frequency range of the target broadband millimeter-wave leaky antenna;

[0022] S2. Coaxial Structure Design Steps: Based on the operating frequency range determined in S1, design the corresponding substrate integrated coaxial structure.

[0023] S3, Suppressing Open Stopband Step: Based on the substrate integrated coaxial structure obtained in S2, fabricate a millimeter-wave leaky antenna with suppressed open stopband phenomenon.

[0024] S4. Enhanced radiation design steps: A metasurface is set above the slot of a millimeter-wave leaky antenna that suppresses the open-band phenomenon to obtain a millimeter-wave leaky antenna with enhanced radiation and suppression of the open-band phenomenon.

[0025] The specific steps in S2 include:

[0026] S201: Import the operating frequency range determined in S1 into the cutoff frequency formula of the substrate integrated waveguide to obtain the distance d between the two rows of vias in the substrate integrated coaxial structure.

[0027] S202: Design the corresponding substrate integration coaxial structure based on the distance d obtained in S201;

[0028] The cutoff frequency in S201 can be calculated using the formula for the cutoff frequency of a substrate integrated waveguide, as follows:

[0029]

[0030] In the formula, ε re denoted as the effective dielectric constant of the waveguide structure, W is the waveguide width, d is the diameter of the metal via, and s is the distance between the centers of two adjacent metal vias in each row.

[0031] The above method, optionally, includes the following specific content in S3:

[0032] S301: A trapezoidal slot is used as a half-wave tapered transmission line to suppress the open stopband phenomenon;

[0033] S302: The period P of the corresponding slot is calculated using the principle of spatial harmonics, thus obtaining a millimeter-wave leaky antenna that suppresses the open stopband phenomenon.

[0034] As can be seen from the above technical solution, compared with the prior art, the present invention provides a broadband millimeter-wave leaky antenna based on substrate-integrated coaxial line and a design method thereof, which has the following beneficial effects:

[0035] 1. This invention employs periodic trapezoidal slots on the substrate-integrated coaxial waveguide, resulting in a wider impedance bandwidth; secondly, it combines this with the method of attaching metasurfaces to eliminate the stopband and improve antenna radiation efficiency.

[0036] 2. The design disclosed in this invention is relatively simpler and does not require the elimination of gaps through additional cycles;

[0037] 3. Through the rational design of the metasurface, this invention can achieve high-gain frequency scanning with high bandwidth. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0039] Figure 1 This is a three-dimensional structural schematic diagram of the single-beam broadband millimeter-wave substrate integrated coaxial leaky wave antenna based on metasurface loading according to the present invention.

[0040] Figure 2 This is a three-dimensional structural schematic diagram of the dual-beam broadband millimeter-wave substrate integrated coaxial leaky wave antenna based on metasurface loading according to the present invention.

[0041] Figure 3 This is a diagram showing the relationship between the radiation angles and periods of the substrate-integrated coaxial waveguide with periodic slots in this invention.

[0042] Figure 4 The dispersion diagrams of the first three modes in the substrate-integrated coaxial waveguide of this invention are shown.

[0043] Figure 5 The scattering parameters for the simulation and measurement of the single-beam broadband millimeter-wave substrate integrated coaxial leaky wave antenna based on metasurface loading in this invention;

[0044] Figure 6 This is the normalized simulation pattern of the single-beam broadband millimeter-wave substrate-integrated coaxial leaky wave antenna based on metasurface loading according to the present invention.

[0045] Figure 7 This is the normalized test pattern of the single-beam broadband millimeter-wave substrate-integrated coaxial leaky wave antenna based on metasurface loading according to the present invention.

[0046] Figure 8 The scanning angle and gain of the simulation and test of the single-beam broadband millimeter-wave substrate integrated coaxial leaky wave antenna based on metasurface loading according to the present invention are shown.

[0047] Figure 9 The graph shows a comparison of the radiation efficiency and gain of the single-beam broadband millimeter-wave substrate integrated coaxial leaky wave antenna based on metasurface loading in this invention, with and without metasurface.

[0048] Figure 10 The scattering parameters of the dual-beam broadband millimeter-wave substrate-integrated coaxial leaky wave antenna based on metasurface loading are obtained from the simulation and measurement of the present invention.

[0049] Figure 11 This is the normalized simulation pattern of the dual-beam broadband millimeter-wave substrate-integrated coaxial leaky wave antenna based on metasurface loading according to the present invention.

[0050] Figure 12 This is the normalized test pattern of the dual-beam broadband millimeter-wave substrate-integrated coaxial leaky wave antenna based on metasurface loading according to the present invention.

[0051] Figure 13 The scanning angle and gain of the simulation and test of the dual-beam broadband millimeter-wave substrate integrated coaxial leaky wave antenna based on metasurface loading according to the present invention are shown.

[0052] Figure 14 This is a comparison of the radiation efficiency of the dual-beam broadband millimeter-wave substrate-integrated coaxial leaky antenna based on metasurface loading of the present invention with and without metasurface loading, and the radiation efficiency of the single-beam substrate-integrated coaxial leaky antenna without metasurface loading.

[0053] Among them, 1-two-dimensional metal metasurface layer, 2-dielectric substrate portion of metasurface, 3-air via, 4-top gap layer of substrate integrated coaxial waveguide, 5-upper dielectric layer of substrate integrated coaxial waveguide, 6-adhesive layer, 7-first port, 8-inner conductor layer of substrate integrated coaxial waveguide, 9-second port, 10-lower dielectric layer of substrate integrated coaxial waveguide, and 11-metal ground plane. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0056] Reference Figure 1 As shown, the present invention discloses a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line, comprising: a coaxial feed section, a substrate-integrated coaxial line waveguide section, and a metasurface layer section with a dielectric substrate;

[0057] The coaxial feed section is located on both sides of the substrate-integrated coaxial waveguide section; the metasurface layer section with dielectric substrate is located on the upper surface of the substrate-integrated coaxial waveguide section.

[0058] The coaxial power supply section includes:

[0059] First port 7 and second port 9;

[0060] The first port 7 and the second port 9 are located at both ends of the inner conductor layer 8;

[0061] The metasurface layer portion with dielectric substrate includes:

[0062] Two-dimensional metal metasurface layer 1 and dielectric substrate portion 2 of metasurface, wherein the two-dimensional metal metasurface layer 1 is disposed on the dielectric substrate portion 2 of metasurface;

[0063] The substrate-integrated coaxial waveguide section includes, from top to bottom, the following components:

[0064] The substrate-integrated coaxial waveguide consists of a top slot layer 4, an upper dielectric layer 5, an adhesive layer 6, an inner conductor layer 8, a lower dielectric layer 10, and a metal ground plane 11.

[0065] Specifically, adhesive layer 6 is used to bond the upper and lower dielectric substrates of the waveguide.

[0066] The first port 7 is used to feed in radio frequency signals; the second port 9 is used to connect an absorption load in actual use to absorb the residual energy at the end of the antenna.

[0067] The coaxial feed section is connected to the substrate-integrated coaxial waveguide, feeding RF energy from feed port 1 and absorbing the remaining energy at the end of the absorption load at feed port 2. The metasurface layer, not connected to the coaxial feed section, is applied above or below the antenna radiating surface to enhance radiation.

[0068] Therefore, the metasurface layer involved in this invention is directly applied above the top metal layer or below the metal ground plane in a substrate-integrated coaxial waveguide.

[0069] Furthermore, each layer is equipped with two rows of air vents 3 for mounting metal screws to fix the structure.

[0070] Furthermore, periodic slots are simultaneously etched on the top layer 4 and the metal ground plane 11 of the substrate-integrated coaxial waveguide, and metasurfaces are attached at the upper and lower radiation apertures to obtain broadband dual-beam radiation.

[0071] Specifically, a three-dimensional schematic diagram of a broadband millimeter-wave dual-beam substrate-integrated coaxial leaky-wave antenna based on metasurface loading is shown below. Figure 2 As shown, it includes coaxial feed (2-6 and 2-8), coaxial-grounded coplanar waveguide-substrate integrated coaxial line adapter, substrate integrated coaxial line waveguide (2-3, 2-4, 2-5, 2-7, 2-9, 2-10), and two metasurface layer sections with dielectric substrates (2-1, 2-2, 2-11, 2-12).

[0072] Part 2-1 is the top two-dimensional metal metasurface layer; Part 2-2 is the dielectric substrate portion of the top metasurface; Part 2-3 is the top slot layer of the substrate-integrated coaxial waveguide; Part 2-4 is the upper dielectric layer of the substrate-integrated coaxial waveguide; Part 2-5 is an adhesive layer used to bond the upper and lower dielectric substrates of the waveguide; Part 2-6 is port 1, used to feed radio frequency signals; Part 2-7 is the inner conductor layer of the substrate-integrated coaxial waveguide; Part 2-8 is port 2, which is used to connect an absorption load to absorb residual energy at the antenna end in actual use; Part 2-9 is the lower dielectric layer of the substrate-integrated coaxial waveguide; Part 2-10 is the bottom slot layer of the substrate-integrated coaxial waveguide, used to leak electromagnetic waves from below and couple them to the metasurface layer below; Part 2-11 is the dielectric substrate layer of the bottom metasurface; and Part 2-12 is the bottom two-dimensional metal metasurface layer.

[0073] A design method for a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line, used to design a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line as described above, includes the following steps:

[0074] S1. Data determination steps: Determine the operating frequency range of the target broadband millimeter-wave leaky antenna;

[0075] S2. Coaxial Structure Design Steps: Based on the operating frequency range determined in S1, design the corresponding substrate integrated coaxial structure.

[0076] S3, Suppressing Open Stopband Step: Based on the substrate integrated coaxial structure obtained in S2, fabricate a millimeter-wave leaky antenna with suppressed open stopband phenomenon.

[0077] S4. Enhanced radiation design steps: A metasurface is set above the slot of a millimeter-wave leaky antenna that suppresses the open-band phenomenon to obtain a millimeter-wave leaky antenna with enhanced radiation and suppression of the open-band phenomenon.

[0078] The specific steps in S2 include:

[0079] S201: Import the operating frequency range determined in S1 into the cutoff frequency formula of the substrate integrated waveguide to obtain the distance d between the two rows of vias in the substrate integrated coaxial structure.

[0080] S202: Design the corresponding substrate integration coaxial structure based on the distance d obtained in S201;

[0081] The cutoff frequency in S201 can be calculated using the formula for the cutoff frequency of a substrate integrated waveguide, as follows:

[0082]

[0083] In the formula, ε re denoted as the effective dielectric constant of the waveguide structure, W is the waveguide width, d is the diameter of the metal via, and s is the distance between the centers of two adjacent metal vias in each row.

[0084] Specifically, the substrate-integrated coaxial structure is similar to that of a coaxial cable, consisting of a dielectric insulating layer, an inner conductor with a metal strip in the middle, and two outer conductors connected by two rows of vias. Compared to substrate-integrated waveguide structures that primarily operate in TE10 mode, it can operate in single-mode (TEM mode) over a wider frequency band. Because the substrate-integrated coaxial waveguide can be approximately equivalent to a planar coaxial cable, and its dominant propagation mode is quasi-TEM mode, its single-mode propagation can cover the cutoff frequency from DC to the first-order higher modes.

[0085] The cutoff frequency of the first-order higher-order mode TE10 of SICL can be estimated by formula (1) for the cutoff frequency of substrate integrated waveguide. It can also be seen from formula (1) that as the waveguide width W increases, the first-order cutoff frequency of the substrate integrated coaxial waveguide will appear at a lower frequency.

[0086] To prevent the influence of higher-order modes, waveguides are typically designed to operate in single-mode mode within the specified frequency band. Therefore, this paper considers the ε of the selected medium... reThe diameter and spacing of the metal vias, as well as the frequency band (20-40GHz) of the antenna, determine the spacing W of the two rows of metal vias, thereby ensuring that the antenna operates in the single-mode range.

[0087] To design a SICL structure operating in the 20–40 GHz frequency range, a SICL structure with a 2.8 mm distance between two rows of vias was designed, and the dispersion curves of the modes in a waveguide with a dielectric constant of 2.2 are given as follows: Figure 3 As shown.

[0088] Furthermore, the specific content of S3 includes:

[0089] S301: A trapezoidal slot is used as a half-wave tapered transmission line to suppress the open stopband phenomenon;

[0090] S302: The period P of the corresponding slot is calculated using the principle of spatial harmonics, resulting in a millimeter-wave leaky antenna that suppresses the open-stopband phenomenon.

[0091] Specifically, to design a millimeter-wave leaky antenna with broadband continuous frequency scanning capability, a trapezoidal slot is used as a half-wave transmission line to suppress the open-stopband phenomenon. Furthermore, the periodicity of the leaky antenna ensures that it always possesses a periodic aperture field. Using spatial harmonic theory, the periodic aperture field can be expanded into infinitely many spatial harmonic terms, where fast waves can radiate, while slow waves are confined within the antenna aperture as surface waves. The phase constant of the -1st harmonic can be expressed as:

[0092]

[0093] Wherein, β0 and β -1 Let β0 be the phase constant of the fundamental harmonic mode and the -1 harmonic mode. In a waveguide structure based on the quasi-TEM mode, β0 can be approximated as:

[0094]

[0095] In the formula ε re Let be the effective dielectric constant of the waveguide structure. Then the scanning angle of the -1st harmonic can be approximately calculated as:

[0096]

[0097] Where θ -1 Let k0 be the beam direction of the -1st harmonic and k0 be the wave number in free space. In this design, the gap period P is set to 5.7 mm, which allows only the -1st spatial harmonic to be excited in the 20–40 GHz operating frequency band. Figure 2 As shown. Where θ -1Let k0 be the beam direction of the -1st harmonic and k0 be the wave number in free space. In this design, the gap period P is set to 5.7 mm, which allows only the -1st spatial harmonic to be excited in the 20–40 GHz operating frequency band. Figure 4 As shown. Based on the principle of harmonic radiation, we can design a substrate-integrated coaxial leaky wave antenna covering the 20-40 GHz frequency band. By designing the slots, we can suppress the open stopband phenomenon, thereby achieving continuous frequency beam scanning in the 20-40 GHz frequency band.

[0098] Furthermore, the specific content of S4 includes:

[0099] By attaching a metasurface to the antenna radiating surface, a millimeter-wave leaky antenna with enhanced radiation and suppression of open-stopband phenomenon is obtained.

[0100] Specifically, leaky antennas with direct slots have low radiation efficiency, so a metasurface layer attached above the slot is designed to enhance radiation. This allows for the design of a broadband millimeter-wave high-gain metasurface substrate integrated coaxial leaky antenna.

[0101] Specifically, to verify the proposed antenna design, the SICL LWA based on the metasurface was designed, fabricated, and measured. Manufacturing was performed using standard printed circuit board (PCB) technology, with multilayer PCBs assembled and secured using screws.

[0102] 1) Single-beam antenna implementation effect

[0103] Figure 5 Simulation and measurement results for the antenna, |S11| and |S21|, are presented, and the simulation and measurement results agree well. A slight shift in the operating frequency may be attributed to an increase in the actual dielectric constant of the substrate, or manufacturing and assembly errors in the antenna. Experimental results show that the antenna has a bandwidth of up to 66.7%, covering a range of 20–40 GHz, making it suitable for millimeter-wave broadband communication systems. Figure 6 and 7 Simulation and measurement normalized radiative maps of SICLLWA based on metasurfaces at different frequencies are presented respectively. Figure 8 The simulated and measured scan angles and gains for each beam are presented. As the frequency increases from 20 GHz to 40 GHz, the measured beam continuously scans within the range of -75° to 18°, showing good agreement with the simulation results. Meanwhile, the gain values ​​for the main beam direction at different frequencies are shown below. Figure 8 As shown. The maximum measured gain reached 17.19 dBi, and the measured side-fire beam gain was 15.07 dBi, indicating successful suppression of the OSB phenomenon. The measured gain agrees well with the simulation results, verifying the broadband radiation performance of the designed antenna. To verify the proposed design concept, Figure 9The gain and efficiency versus frequency curves with and without a metasurface are shown, revealing a significant improvement after loading the metasurface array. The average in-band gain increases by approximately 4 dB after loading the radiation-enhancing metasurface. Furthermore, the antenna's in-band radiation efficiency is also greatly improved. The metasurface SICL LWA antenna with a radiation efficiency exceeding 50% has a bandwidth of approximately 50% (24–40 GHz), meeting the requirements of future millimeter-wave broadband antennas.

[0104] 2) Dual-beam antenna implementation effect

[0105] Figure 10 Simulation and measurement results (S11 and S21) for the dual-beam SICL LWA antenna are presented, and the measurement results agree well with the simulation results. The experimental results show that the antenna bandwidth is as high as 66.7%, with a coverage range of 20–40 GHz, making it suitable for dual-target millimeter-wave broadband communication systems. Figure 11 and 12 Simulation and measurement normalized radiograms of SICL LWA based on metasurfaces at different frequencies are presented, and the results show good agreement. Figure 13 The simulated and measured scanning angles and gains for each beam are presented. Measured beams 1 and 2 were continuously scanned within the ranges of -65° to 17° and 224° to 153°, respectively, and showed good consistency with the simulated results in the 20–40 GHz frequency band. Furthermore, the gain values ​​and scanning angles of each beam in the main beam direction at different frequencies are shown below. Figure 13 As shown, considering the good symmetry of the antenna's upper and lower spaces, only the beam angle of the upper half space (-90° to 90°) is given, which agrees well with the simulation results. The maximum measured gain reaches 14.58 dBi, and the measured gain of the side-fire beam is 13.93 dBi, indicating that by adding two metasurface layers at the top and bottom of the antenna, the OSB phenomenon is successfully suppressed while improving radiation efficiency. Figure 14 Given the radiation efficiencies of single-beam LWA without metasurface, dual-beam LWA without metasurface, and LWA with metasurface for the same slot size, we can deduce the following:

[0106] (1) The dual-leakage-source method can enhance leakage due to the presence of two leakage sources, thereby improving efficiency to a certain extent. However, due to the limitations of the waveguide structure, the total radiation efficiency of the antenna is still relatively low.

[0107] (2) Adding a metasurface to the radiation aperture of the dual radiation source can simultaneously enhance the radiation of the dual beams, thus designing a SICL LWA based on a dual-beam broadband metasurface.

[0108] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0109] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line, characterized in that, include: The coaxial feed section, the substrate-integrated coaxial waveguide section, and the metasurface layer section with dielectric substrate; The coaxial feed section is located on both sides of the substrate-integrated coaxial waveguide section; the metasurface layer section with dielectric substrate is located on the upper surface of the substrate-integrated coaxial waveguide section. The coaxial power supply section includes: First port (7) and second port (9); The first port (7) and the second port (9) are located at both ends of the inner conductor layer (8); The first port (7) is used to feed in radio frequency signals; the second port (9) is used to connect an absorption load in actual use to absorb the residual energy at the end of the antenna. The metasurface layer portion with dielectric substrate includes: Two-dimensional metal metasurface layer (1) and dielectric substrate portion (2) of metasurface, wherein the two-dimensional metal metasurface layer (1) is disposed on the dielectric substrate portion (2) of metasurface; The substrate-integrated coaxial waveguide section includes, from top to bottom, the following components: The substrate integrated coaxial waveguide has a top slot layer (4), an upper dielectric layer (5), an adhesive layer (6), an inner conductor layer (8), a lower dielectric layer (10), and a metal ground plane (11). The substrate-integrated coaxial waveguide has periodic trapezoidal slots on the top slot layer (4).

2. The broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line according to claim 1, characterized in that, Two rows of air vents (3) are provided on each layer for installing metal screws to fix the structure.

3. The broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line according to claim 1, characterized in that, Periodic slots are etched in the metal ground plane (11) of the coaxial waveguide section integrated on the substrate, and a metasurface is attached at the upper and lower radiation apertures to obtain broadband dual-beam radiation.

4. A design method for a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line, characterized in that, The method for designing a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line as described in any one of claims 1-3 includes the following steps: S1. Data determination steps: Determine the operating frequency range of the target broadband millimeter-wave leaky antenna; S2. Coaxial Structure Design Steps: Based on the operating frequency range determined in S1, design the corresponding substrate integrated coaxial structure. S3, Suppressing Open Stopband Step: Based on the substrate integrated coaxial structure obtained in S2, fabricate a millimeter-wave leaky antenna with suppression of open stopband phenomenon. S4. Enhanced radiation design steps: A metasurface is set above the slot of a millimeter-wave leaky antenna that suppresses the open-band phenomenon to obtain a millimeter-wave leaky antenna with enhanced radiation and suppression of the open-band phenomenon. The specific steps in S2 include: S201: Import the operating frequency range determined in S1 into the cutoff frequency formula of the substrate integrated waveguide to obtain the distance between the two rows of vias in the substrate integrated coaxial structure. d ; S202: Distance obtained from S201 d Design the corresponding substrate-integrated coaxial structure; The cutoff frequency in S201 is calculated using the formula for the cutoff frequency of the substrate integrated waveguide, as follows: (1) In the formula, ε re The effective dielectric constant of the waveguide structure is _____. W For waveguide width, d The diameter of the metal through hole. s The distance between the centers of two adjacent metal through holes in each row.

5. The design method for a broadband millimeter-wave leaky antenna based on a substrate-integrated coaxial line according to claim 4, characterized in that, The specific content of S3 includes: S301: A trapezoidal slot is used as a half-wave tapered transmission line to suppress the open stopband phenomenon; S302: The period P of the corresponding slot is calculated using the principle of spatial harmonics, thus obtaining a millimeter-wave leaky antenna that suppresses the open stopband phenomenon.

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