A linear beam scanning leaky-wave antenna based on group-delay tuning

Abstract

This invention discloses a linear beam scanning leaky antenna based on group delay modulation, belonging to the field of leaky antenna technology. The main body of the antenna is composed of several cascaded leaky antenna units, with impedance matching sections configured at both ends of the overall structure. Each leaky antenna unit includes a substrate integrated waveguide, a first pair of diaphragms (1), a second pair of diaphragms (2), and a transverse slot (3). The substrate integrated waveguide is composed of a first dielectric substrate (4), a first grounded metal surface (5), a first metal surface (6), and two rows of first metal vias (7). The impedance matching sections at both ends include a microstrip matching structure and a gradient substrate integrated waveguide structure, with several transverse slots (16) of varying lengths set on the surface of the gradient substrate integrated waveguide. The antenna structure of this invention is simple, has strong processing compatibility, and excellent scanning linearity, and can be widely adapted to high-frequency millimeter-wave application scenarios such as 5G / 6G wireless communication, high-resolution millimeter-wave radar, and wireless power transmission.

Description

Technical Field

[0001] This invention belongs to the field of leaky wave antenna technology, specifically relating to a substrate integrated waveguide leaky wave antenna, and more particularly to a quasi-uniform transverse slot leaky wave antenna that achieves linear beam scanning based on group delay modulation, which can be applied to 5G / 6G wireless communication, high-resolution millimeter-wave radar, wireless power transmission and other fields. Background Technology

[0002] With the rapid evolution of 5G / 6G wireless communication, high-resolution radar, and wireless power transfer technologies, beam-scanning antennas, which combine high spatial utilization and wide coverage, have become a core component of modern wireless systems. Currently, commonly used beam-scanning schemes mainly include mechanical scanning, phased array scanning, multi-beam array scanning, and frequency scanning. Mechanical scanning achieves beam scanning by moving the antenna structure, but it suffers from slow scanning rates, large system size, and heavy weight, making it difficult to adapt to the miniaturized, high-scanning-rate application requirements. Phased array scanning achieves beam scanning by introducing controllable phase differences, which can improve the scanning rate, but the use of numerous phase shifters and transceiver components increases hardware complexity, system cost, and power consumption. Multi-beam array technology achieves beam scanning through feed networks or beamforming algorithms, enabling parallel spatial coverage and improving spectrum utilization, but it suffers from structural complexity, significant losses, and large size.

[0003] In contrast, frequency scanning mechanisms, exemplified by leaky wave antennas, utilize the dispersion characteristics between the propagation constant and frequency in the antenna structure to achieve continuous beam scanning simply by changing the frequency. This beam scanning mechanism completely eliminates the reliance on expensive phase shifters and complex beamforming networks, significantly reducing system complexity, profile height, and manufacturing costs, and has broad application prospects in wireless systems. However, because the beam scanning law of leaky wave antennas is limited by the dispersion relationship of the waveguide structure, the main beam angle θ is affected. m The relationship between the frequency and the operating frequency f is typically nonlinear, which presents numerous challenges for leaky-wave antennas in practical applications. For example, in frequency-modulated continuous-wave radar, the nonlinear frequency-angle relationship can induce range-angle coupling errors, significantly increasing the difficulty of back-end signal processing and system calibration; in broadband wireless communication, nonlinearly scanned beams can exacerbate beam squint effects and reduce the predictability of beam pointing. Therefore, achieving θ m The linear variation of f, i.e., the linear beam scanning leaky antenna, has extremely important engineering value for simplifying system architecture and improving radar sensing and communication capabilities.

[0004] Current technologies primarily optimize antenna dispersion and improve beam scanning linearity by loading symmetrical periodic probes, constructing artificial surface plasmon structures, and designing rippled periodic transmission lines. However, most existing designs rely on reverse engineering and trial-and-error optimization, depending on repeated adjustments of structural parameters by designers. This lack of a unified and universally applicable theoretical design system results in low design efficiency and limited improvement in antenna linearity, failing to meet the demands of high-precision millimeter-wave applications. To address these shortcomings, there is an urgent need for a linear beam scanning leaky-wave antenna with comprehensive theoretical support, a simple structure, excellent linearity, and the capability for mass engineering application. Summary of the Invention

[0005] Technical Problem: This invention aims to solve the technical problems of existing linear beam scanning leaky antennas, such as the lack of universal forward design theory, reliance on parameter trial and error optimization, poor beam scanning linearity, and weak engineering practicality. It provides a linear beam scanning leaky antenna based on group delay control, which relies on the analytical correlation between group delay and beam scanning rate to achieve forward and accurate design of the antenna's linear scanning performance, while taking into account both structural simplicity and superior scanning performance.

[0006] Technical Solution: To achieve the above objectives, the present invention provides a linear beam scanning leaky antenna based on group delay modulation, employing the following technical solution: The present invention discloses a linear beam scanning leaky antenna based on group delay modulation, comprising a plurality of cascaded leaky antenna elements and impedance matching sections respectively disposed at both ends of the cascaded leaky antenna elements; each leaky antenna element includes a plurality of transverse slots arranged sequentially along the antenna length direction on the upper surface of a substrate integrated waveguide, and a first pair of diaphragms and a second pair of diaphragms are disposed on both sides of the sequentially arranged transverse slots; the substrate integrated waveguide includes a first dielectric substrate, a first grounded metal surface on the lower surface of the first dielectric substrate, a first metal surface on the upper surface of the first dielectric substrate, and first metal vias on both sides of the transverse slots; the impedance matching section includes a microstrip pair. The microstrip matching structure includes a third dielectric substrate, a third grounded metal surface on the lower surface of the third dielectric substrate, a 50-ohm fed microstrip line on the upper surface of the third dielectric substrate, and an impedance matching microstrip line connected to the 50-ohm fed microstrip line. The gradient substrate integrated waveguide structure includes a second dielectric substrate, a second grounded metal surface on the lower surface of the second dielectric substrate, and a second metal surface on the upper surface of the second dielectric substrate. Several transverse slots with varying lengths are provided on the second metal surface along the length direction of the gradient substrate integrated waveguide structure. Second metal vias are arranged on both sides of the transverse slots with varying lengths.

[0007] The width of the 50-ohm fed microstrip line is greater than the width of the impedance matching microstrip line. One end of the impedance matching microstrip line is connected to the 50-ohm fed microstrip line, and the other end of the impedance matching microstrip line is connected to the second metal surface.

[0008] When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the substrate integrated waveguide unit is... l The width w1 is 10.0 mm, the thickness of the first dielectric substrate of the substrate integrated waveguide is 0.508 mm, and the inter-column width w2 of the two columns of the first metal vias is 3.80 mm.

[0009] When the antenna operates in the 26.7-28.1 GHz frequency band, the spacing between the first pair of diaphragms and the second pair of diaphragms... l 2 is 3.00 mm, and the distance w3 between the two membranes in the same pair is 3.20 mm.

[0010] The transverse slots are uniformly etched on the first metal surface of the substrate integrated waveguide. When the antenna operates in the 26.7-28.1 GHz frequency band, the length of each transverse slot is 2.20 mm and the width is 0.20 mm.

[0011] When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the third dielectric substrate of the microstrip matching structure... l 3 is 6.00 mm, w4 is 15.00 mm wide, and 0.508 mm thick; the 50-ohm fed microstrip line is 4.20 mm long and 1.30 mm wide, and the impedance matching microstrip line is 1.80 mm long and 0.800 mm wide.

[0012] When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the graded substrate integrated waveguide structure... l 4 is 13.80 mm, w5 is 10.00 mm, and the thickness of the second dielectric substrate is 0.508 mm; the inter-row spacing w6 of the two rows of second metal vias in the gradient substrate integrated waveguide structure is 3.80 mm.

[0013] When the antenna operates in the 26.7-28.1 GHz frequency band, the width of the length-gradient transverse slot on the gradient substrate integrated waveguide structure is 0.200 mm, and the slot length linearly changes from 2.20 mm to 0.220 mm along the transmission direction.

[0014] The antenna's preset operating frequency band is 26.7 GHz-28.1 GHz, and the antenna parameters within the operating frequency band satisfy |S 11 |<-10.0 dB, |S 21|<-11.5 dB; The average absolute error of the antenna main beam angle as a function of frequency is 0.505°, and the main beam angle has a linear relationship with frequency.

[0015] The core design method of this invention is: the core innovation of this invention lies in establishing group delay. The quantitative analytical relationship between the beam scanning rate S(f) and the operating frequency band is achieved by adjusting the operating frequency band. By utilizing the flatness characteristic, S(f) is kept constant, ultimately achieving a linear beam scanning effect. The specific theoretical derivation is as follows: The beam scanning rate of a leaky antenna satisfies the following formula: , In the formula: k0 is the free space wavenumber, l 1 represents the length of the leaky antenna element. For antenna group delay, θ m β is the main beam angle measured from the side-firing direction using a leaky antenna. e The effective phase constant; due to the limited beam scanning range of the quasi-uniform leaky wave antenna, if adjustments are made... During the process, keep k0 and l If the effect of 1 on S(f) remains unchanged, then S(f) will be changed by... Decide.

[0016] Define a beam scanning linearity parameter L to quantify the linear performance of beam scanning. The calculation formula is as follows: , The linearity parameter L physically represents the rate of change of the beam scanning rate with frequency. When L = 0, it means that the scanning rate S(f) does not change with frequency and remains constant. At this time, the antenna main beam angle θ m It has a strict linear relationship with the operating frequency, which is the ideal linear beam scanning state.

[0017] Based on the above formula, a complete technical judgment logic can be formed: when the group delay of the leaky antenna... Maintaining flat characteristics within the preset operating frequency band The numerical values ​​show no significant fluctuations. Combined with formula (1), it can be determined that the S(f) of the leaky antenna remains stable. A stable S(f) ensures that the frequency change rate of S(f) in formula (2) is zero, thus satisfying the linear scanning condition of L = 0. In summary, it can be proven that by adjusting the structural parameters, the operating frequency band of the leaky antenna can be controlled within a certain range. Flattening enables high linearity beam scanning performance of leaky wave antennas.

[0018] This invention adjusts the inter-row width w2 of the metal through-hole and the unit length. l1. The operating passband range of the leaky wave antenna can be flexibly adjusted; this can be achieved by adjusting the spacing between the two pairs of diaphragms. l 2. Precisely control the dispersion characteristics of the substrate-integrated waveguide to enable operation within the specified frequency band. The curve tends to flatten. Ultimately, linear beam scanning leaky antennas adapted to different frequency bands can be customized.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following outstanding advantages: 1. Proposing a theoretical forward design system to break through industry technical bottlenecks: Based on the analytical correlation between group delay and scanning rate, this invention establishes a forward design method for linear beam scanning leaky antennas, eliminating the need for repeated parameter adjustments in traditional techniques and significantly improving design efficiency. Furthermore, this design theory is not limited to substrate-integrated waveguide structures and can be adapted to various transmission structures such as rectangular waveguides and microstrip lines, possessing strong versatility and engineering application value.

[0020] 2. Excellent beam scanning linearity: The average absolute error of the linear fitting of the main beam angle of the leaky antenna of this invention is 0.505°, which is significantly improved compared with the error of more than 1.00° of existing similar leaky antennas. This can effectively avoid radar ranging and angle coupling errors and reduce the difficulty of back-end signal processing.

[0021] 3. Flexible adjustment of operating frequency band and scanning performance: By adjusting the antenna unit size and diaphragm structure parameters, the antenna operating frequency band and group delay flatness characteristics can be adjusted separately, and the beam scanning linearity can be optimized as needed to adapt to the needs of multi-scenario and multi-frequency band millimeter wave wireless applications.

[0022] 4. Simple structure and strong engineering applicability: The antenna of this invention adopts a substrate integrated waveguide, diaphragm and lateral slot structure that is compatible with standard PCB process. It has no complex active devices and precision structure. The processing technology is mature and the cost is low, which can realize mass production. At the same time, the low profile structure characteristics are suitable for miniaturized integrated equipment. Attached Figure Description

[0023] Figure 1 is a schematic diagram of a unit of a linear beam scanning leaky wave antenna based on group delay modulation according to an example of the present invention. Figure 1 (a) in the diagram is a schematic diagram of the three-dimensional structure. Figure 1 (b) in the diagram is a top view of the structure; Figure 2 is a schematic diagram of the impedance matching section of a linear beam scanning leaky wave antenna based on group delay modulation according to an example of the present invention. Figure 2 (a) in the diagram is a schematic diagram of the three-dimensional structure. Figure 2 (b) in the diagram is a top view of the structure; Figure 3 is a top view of a linear beam scanning leaky antenna based on group delay modulation, according to an example of the present invention. Figure 4 shows the simulated group delay of a linear beam scanning leaky antenna based on group delay modulation, according to an example of the present invention. Images of scan rate S(f) and linearity L; Figure 5 shows the S-parameter curves of a linear beam scanning leaky wave antenna based on group delay modulation, according to an example of the present invention. Figure 6 shows the radiation efficiency and peak gain curves of a linear beam scanning leaky antenna based on group delay modulation, according to an example of the present invention. Figure 7 shows the radiation pattern of a simulated linear beam scanning leaky antenna based on group delay modulation, according to an example of the present invention. Figure 8 is a simulation diagram of the main beam angle of a linear beam scanning leaky wave antenna based on group delay modulation according to an example of the present invention. Figure 9 is a flowchart of the invention implementation process.

[0024] The figure includes: 1. First pair of diaphragms; 2. Second pair of diaphragms; 3. Lateral slit; 4. First dielectric substrate; 5. First ground metal surface; 6. First metal surface; 7. First metal via; 8. Third dielectric substrate; 9. Third ground metal surface; 10. 50-ohm fed microstrip line; 11. Impedance matching microstrip line; 12. Second dielectric substrate; 13. Second ground metal surface; 14. Second metal surface; 15. Second metal via; 16. Lateral slit with gradually changing length. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0026] This invention discloses a linear beam scanning leaky antenna based on group delay modulation, comprising a plurality of cascaded leaky antenna elements and impedance matching sections respectively disposed at both ends of the cascaded leaky antenna elements; each leaky antenna element includes a plurality of transverse slots 3 arranged sequentially along the antenna length direction on the upper surface of a substrate integrated waveguide, and a first pair of diaphragms 1 and a second pair of diaphragms 2 are provided on both sides of the sequentially arranged transverse slots 3; the substrate integrated waveguide includes a first dielectric substrate 4, a first grounded metal surface 5 located on the lower surface of the first dielectric substrate 4, a first metal surface 6 located on the upper surface of the first dielectric substrate 4, and first metal vias 7 located on both sides of the transverse slots 3; the impedance matching section includes a microstrip matching structure and a gradient substrate integrated waveguide. The waveguide structure comprises a third dielectric substrate 8, a third grounded metal surface 9 on the lower surface of the third dielectric substrate 8, a 50-ohm fed microstrip line 10 on the upper surface of the third dielectric substrate 8, and an impedance matching microstrip line 11 connected to the 50-ohm fed microstrip line 10. The gradient substrate integrated waveguide structure comprises a second dielectric substrate 12, a second grounded metal surface 13 on the lower surface of the second dielectric substrate 12, and a second metal surface 14 on the upper surface of the second dielectric substrate 12. A plurality of transversely spaced slots 16 with varying lengths are provided on the second metal surface 14 along the length direction of the gradient substrate integrated waveguide structure. Second metal vias 15 are arranged on both sides of the transversely spaced slots 16. The width of the 50-ohm fed microstrip line 10 is greater than the width of the impedance matching microstrip line 11. One end of the impedance matching microstrip line 11 is connected to the 50-ohm fed microstrip line 10, and the other end of the impedance matching microstrip line 11 is connected to the second metal surface 14.

[0027] When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the substrate integrated waveguide unit is... l The thickness of the first dielectric substrate 4 of the substrate integrated waveguide is 0.508 mm, and the width w1 is 10.0 mm. The inter-row width w2 of the two columns of the first metal through holes 7 is 3.80 mm.

[0028] When the antenna operates in the 26.7-28.1 GHz frequency band, the spacing between the first pair of diaphragms 1 and the second pair of diaphragms 2 is... l 2 is 3.00 mm, and the distance w3 between the two membranes in the same pair is 3.20 mm.

[0029] The transverse slots 3 are uniformly etched on the first metal surface 6 of the substrate integrated waveguide. When the antenna operates in the 26.7-28.1 GHz frequency band, the length of each transverse slot 3 is 2.20 mm and the width is 0.20 mm.

[0030] When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the third dielectric substrate 8 of the microstrip matching structure...l 3 is 6.00 mm, w4 is 15.00 mm wide, and 0.508 mm thick; the 50-ohm fed microstrip line 10 is 4.20 mm long and 1.30 mm wide, and the impedance matching microstrip line 11 is 1.80 mm long and 0.800 mm wide.

[0031] When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the graded substrate integrated waveguide structure... l 4 is 13.80 mm, w5 is 10.00 mm, and the thickness of the second dielectric substrate 12 is 0.508 mm; the inter-row spacing w6 of the two rows of second metal vias 15 in the gradient substrate integrated waveguide structure is 3.80 mm.

[0032] When the antenna operates in the 26.7-28.1 GHz frequency band, the width of the length-gradient transverse slots 16 on the gradient substrate integrated waveguide structure is 0.200 mm, and the slot length linearly changes from 2.20 mm to 0.220 mm along the transmission direction.

[0033] The antenna's preset operating frequency band is 26.7 GHz-28.1 GHz, and the antenna parameters within the operating frequency band satisfy |S 11 |<-10.0 dB, |S 21 |<-11.5 dB; The average absolute error of the antenna main beam angle as a function of frequency is 0.505°, and the main beam angle has a linear relationship with frequency.

[0034] The antenna is designed using the following method: establishing a group delay. The quantitative analytical relationship between the beam scanning rate S(f) and the operating frequency band is achieved by adjusting the operating frequency band. By utilizing the flatness characteristic, S(f) is kept constant, ultimately achieving a linear beam scanning effect, as detailed below: The beam scanning rate of a leaky antenna satisfies the following formula: , In the formula: k0 is the free space wavenumber, l 1 represents the length of the leaky antenna element. For antenna group delay, θ m β is the main beam angle measured from the side-firing direction using a leaky antenna. e The effective phase constant is given by cosθ; due to the limited beam scanning range of the quasi-uniform leaky wave antenna, cosθ m The numerical fluctuations are small, and their impact on S(f) can be approximated. Therefore, the variation characteristics of the scan rate S(f) are mainly determined by k0, and l 1. Decision. If adjustments are made... During the process, keep k0 and l If the effect of 1 on S(f) remains unchanged, then S(f) will be changed by... Decide; Define a beam scanning linearity parameter L to quantify the linear performance of beam scanning. The calculation formula is as follows: ,

[0035] The linearity parameter L physically represents the rate of change of the beam scanning rate with frequency; when L = 0, it means that the scanning rate S(f) does not change with frequency and remains constant, at which point the antenna main beam angle θ m It has a strict linear relationship with the operating frequency, which is the ideal linear beam scanning state.

[0036] The linear beam scanning leaky antenna is formed by cascading twenty identical leaky antenna elements. Impedance matching sections are symmetrically set at both ends of the antenna to achieve feed impedance matching and smooth switching of transmission modes.

[0037] The leaky antenna element uses a Rogers RO3003 dielectric substrate with a relative permittivity ε. r = 3.00, loss tangent tanδ = 0.001, and substrate thickness uniformly set to 0.508 mm. The upper and lower surfaces of the dielectric substrate are completely copper-clad, forming the top metal surface and ground metal surface, respectively. Two rows of equally spaced metal vias are used to construct the substrate integrated waveguide transmission structure. A first pair of diaphragms and a second pair of diaphragms are loaded inside the substrate integrated waveguide to form a periodic filtering structure, used to control dispersion and group delay characteristics. Five uniformly sized transverse slits are uniformly etched on the top metal surface of the substrate integrated waveguide as a leakage radiation structure.

[0038] The impedance matching sections at both ends are divided into two parts: the front part is a microstrip matching structure, which consists of a 50-ohm feed microstrip line and an impedance matching microstrip line, to achieve impedance transition matching between the 50-ohm standard feed port and the standard substrate integrated waveguide; the rear part is a gradient substrate integrated waveguide structure, with eleven transverse slots of linearly varying lengths on the surface of the structure, to achieve impedance transition matching between the standard substrate integrated waveguide and the leaky wave antenna element, reduce port reflection loss, and improve antenna radiation stability.

[0039] The embodiments of this invention use Rogers RO3003 dielectric substrate with a thickness of 0.508 mm and a relative permittivity ε. r =3.00, loss tangent tanδ=0.001, and the entire process adopts standard PCB manufacturing technology.

[0040] Step 1: Design of Leaky Wave Antenna Unit

[0041] A rectangular first dielectric substrate 4 with dimensions of 6.00 mm × 10.00 mm is fabricated, with the upper and lower surfaces of the substrate completely copper-clad to construct a first ground metal surface 5 and a first metal surface 6. Two rows of first metal vias 7 are provided to form a substrate integrated waveguide transmission structure, with a via spacing w2 = 3.80 mm. A first pair of diaphragms 1 and a second pair of diaphragms 2 are loaded inside the substrate integrated waveguide structure, with a spacing between the diaphragm pairs. l 2 = 3.00 mm, the spacing between the two diaphragms in the same pair is w3 = 3.20 mm, and five transverse slots 3 are uniformly etched on the first top metal surface 6. The slot dimensions are uniformly 2.20 mm in length and 0.20 mm in width, forming a complete leaky wave antenna unit, such as Figure 1 As shown. By configuring the above parameters, the leaky antenna element maintains a highly flat group delay within the 26.5-28.3 GHz frequency band, as... Figure 4 As shown.

[0042] Step 2: Impedance Matching Section Design

[0043] Impedance matching sections are provided at both ends of the antenna. The front section is a microstrip matching structure: the third dielectric substrate 8 measures 6.00 mm × 15.00 mm, integrating a 4.20 mm × 1.30 mm 50-ohm feed microstrip line 10 and a 1.80 mm × 0.800 mm impedance matching microstrip line 11, achieving a smooth transition of port impedance. The rear section is a gradient substrate integrated waveguide structure, with an overall size of 13.80 mm × 10.00 mm. Eleven 0.200 mm wide and 0.220 mm long gradient transverse slots 16 are etched on the surface of the structure. The slot length linearly changes from 2.20 mm to 0.220 mm along the electromagnetic wave propagation direction, achieving smooth switching of transmission modes and reducing port reflection loss. The complete impedance matching section structure is shown below. Figure 2 As shown.

[0044] Step 3: Overall Antenna Assembly

[0045] Twenty identical leaky antenna elements are cascaded sequentially, and impedance matching sections are assembled at both ends of the cascaded structure to complete the overall antenna assembly. Figure 3 As shown. The entire invention implementation process described above is as follows: Figure 9 As shown.

[0046] Antenna performance simulation:

[0047] The S-parameters of the leaky antenna simulation are as follows: Figure 5 As shown, within the operating frequency band of 26.7-28.1 GHz, |S 11 |<-10.0dB,|S 21 |<-11.5 dB. The simulated radiation efficiency and peak realized gain of the leaky antenna are as follows: Figure 6As shown, within the operating frequency band of 26.7-28.1 GHz, the average radiation efficiency is 54.5%, and the average peak realized gain is 14.4 dBi. The simulated radiation pattern of the leaky-wave antenna is shown below. Figure 7 As shown, good beam scanning characteristics were achieved within the operating frequency band of 26.7-28.1 GHz. To reflect the linearity of the leaky-wave antenna's beam scanning, in Figure 8 The curve showing the main beam angle as a function of frequency is presented, along with an ideal straight line for reference. It is evident that the main beam angle curve closely approximates the ideal straight line. Furthermore, to quantitatively demonstrate the beam scanning linearity of the leaky wave antenna, the mean absolute error (MAVE) can be calculated. The formula for MAVE is as follows: , Where N is the total number of measurement points, θ i and T i Let MAVE represent the point on the i-th main beam angle curve and the point on the ideal straight line at the same frequency, respectively. A smaller MAVE value means the main beam angle curve is closer to the ideal straight line, indicating better linear scanning performance of the leaky antenna. Calculations show that the MAVE of the linear beam scanning leaky antenna proposed in this invention is 0.505°, while the MAVE of existing linear beam scanning leaky antennas is above 1.00°. Therefore, by comparing MAVE values, it can be seen that the linear beam scanning leaky antenna based on group delay modulation of this invention has excellent linearity.

[0048] Key parameter adjustment and verification: 1. Passband adjustment: By adjusting the length of the substrate integrated waveguide unit. l 1. The inter-row width w2 of the metal through-hole allows for flexible adjustment of the center frequency and bandwidth of the antenna's operating passband, adapting to different frequency band application scenarios.

[0049] 2. Group delay adjustment: By adjusting the spacing between the two pairs of diaphragms. l 2. It can precisely adjust the flatness of the group delay within the working frequency band, thereby optimizing the beam scanning linearity and achieving optimal performance matching.

[0050] 3. Performance Verification: The above embodiment was simulated using CST Studio Suite software. The simulation results show that the antenna has good impedance matching within the operating frequency band. Figure 5 As shown; the radiation efficiency and peak gain meet the requirements of engineering applications, such as... Figure 6 As shown; the main beam angle exhibits good linear variation with frequency, such as Figure 8 As shown, this verifies the theoretical feasibility and practical effectiveness of the present invention.

[0051] Precautions: 1. All diaphragms used in this invention are non-radiative structures, used only for dispersion and group delay control, to avoid introducing stray radiation interference and ensure the purity of the antenna radiation pattern.

[0052] 2. The length of all transverse gaps is less than the width between the metal vias in the substrate integrated waveguide structure, to avoid cutting the metal vias and damaging the waveguide transmission structure, thus ensuring stable electromagnetic wave transmission.

[0053] 3. The lateral gap spacing of the leaky wave unit is much smaller than the waveguide wavelength in the operating frequency band, which meets the design criteria of quasi-uniform leaky wave antenna and ensures radiation uniformity.

[0054] 4. The impedance matching section must ensure structural dimensional accuracy to ensure good port impedance matching, minimize transmission loss, and improve the overall radiation efficiency of the antenna.

[0055] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A linear beam scanning leaky-wave antenna based on group-delay tuning, characterized by, The system includes several cascaded leaky antenna units and impedance matching sections located at both ends of the cascaded leaky antenna units. Each leaky antenna unit includes several transverse slots (3) arranged sequentially along the antenna length on the upper surface of the substrate integrated waveguide. A first pair of diaphragms (1) and a second pair of diaphragms (2) are provided on both sides of the sequentially arranged transverse slots (3). The substrate integrated waveguide includes a first dielectric substrate (4), a first grounded metal surface (5) on the lower surface of the first dielectric substrate (4), a first metal surface (6) on the upper surface of the first dielectric substrate (4), and first metal vias (7) on both sides of the transverse slots (3). The impedance matching section includes a microstrip matching structure and a gradient substrate integrated waveguide structure. The microstrip matching structure includes a first... The three dielectric substrates (8), the third ground metal surface (9) located on the lower surface of the third dielectric substrate (8), the 50-ohm fed microstrip line (10) located on the upper surface of the third dielectric substrate (8), and the impedance matching microstrip line (11) connected to the 50-ohm fed microstrip line (10), the gradient substrate integrated waveguide structure includes a second dielectric substrate (12), a second ground metal surface (13) located on the lower surface of the second dielectric substrate (12), and a second metal surface (14) located on the upper surface of the second dielectric substrate (12). A plurality of length-gradient transverse slots (16) are provided on the second metal surface (14) along the length direction of the gradient substrate integrated waveguide structure, and second metal through holes (15) are arranged on both sides of the length-gradient transverse slots (16).

2. The linear beam scanning leaky-wave antenna based on group-delay tuning of claim 1, wherein, The width of the 50-ohm fed microstrip line (10) is greater than the width of the impedance matching microstrip line (11). One end of the impedance matching microstrip line (11) is connected to the 50-ohm fed microstrip line (10), and the other end of the impedance matching microstrip line (11) is connected to the second metal surface (14).

3. The linear beam scanning leaky antenna based on group delay modulation according to claim 1, characterized in that, When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the substrate integrated waveguide unit is... l The thickness of the first dielectric substrate (4) of the substrate integrated waveguide is 0.508 mm, and the width w1 is 10.0 mm. The width w2 between the two columns of the first metal through holes (7) is 3.80 mm.

4. The linear beam scanning leaky-wave antenna based on group-delay tuning of claim 1, wherein, When the antenna operates in the 26.7-28.1 GHz frequency band, the spacing between the first pair of diaphragms (1) and the second pair of diaphragms (2) is... l 2 is 3.00 mm, and the distance w3 between the two diaphragms in the same pair is 3.20 mm.

5. The linear beam scanning leaky-wave antenna based on group-delay tuning of claim 1, wherein, The transverse slots (3) are uniformly etched on the first metal surface (6) of the substrate integrated waveguide. When the antenna operates in the 26.7-28.1 GHz frequency band, the length of each transverse slot (3) is 2.20 mm and the width is 0.20 mm.

6. The linear beam scanning leaky-wave antenna based on group-delay tuning of claim 1, wherein, When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the third dielectric substrate (8) of the microstrip matching structure is... l 3 is 6.00 mm, w4 is 15.00 mm, and the thickness is 0.508 mm; the 50-ohm fed microstrip line (10) is 4.20 mm long and 1.30 mm wide, and the impedance matching microstrip line (11) is 1.80 mm long and 0.800 mm wide.

7. The linear beam scanning leaky-wave antenna based on group-delay tuning of claim 1, wherein, When the antenna operates in the 26.7-28.1 GHz frequency band, the length of the graded substrate integrated waveguide structure... l 4 is 13.80 mm, width w5 is 10.00 mm, and the thickness of the second dielectric substrate (12) is 0.508 mm; the inter-column spacing w6 of the two columns of second metal vias (15) in the gradient substrate integrated waveguide structure is 3.80 mm.

8. The linear beam scanning leaky-wave antenna based on group-delay tuning of claim 1, wherein, When the antenna operates in the 26.7-28.1 GHz frequency band, the width of the length-gradient transverse slot (16) on the gradient substrate integrated waveguide structure is 0.200 mm, and the slot length linearly changes from 2.20 mm to 0.220 mm along the transmission direction.

9. The linear beam scanning leaky-wave antenna based on group-delay tuning of claim 1, wherein, The antenna's preset operating frequency band is 26.7 GHz-28.1 GHz, and the antenna parameters within the operating frequency band satisfy |S 11 |<-10.0dB,|S 21 |<-11.5 dB; The average absolute error of the antenna main beam angle as a function of frequency is 0.505°, and the main beam angle has a linear relationship with frequency.

10. The linear beam scanning leaky-wave antenna based on group-delay tuning of claim 1, wherein, The antenna is designed using the following method: establishing a group delay. The quantitative analytical relationship between the beam scanning rate S(f) and the operating frequency band is achieved by adjusting the operating frequency band. By utilizing the flatness characteristic, S(f) is kept constant, ultimately achieving a linear beam scanning effect, as detailed below: The beam scanning rate of a leaky antenna satisfies the following formula: ， In the formula: k0 is the free space wavenumber, l 1 represents the length of the leaky antenna element. For antenna group delay, θ m β is the main beam angle measured from the side-firing direction using a leaky antenna. e The effective phase constant; due to the limited beam scanning range of the quasi-uniform leaky wave antenna, if adjustments are made... During the process, keep k0 and l If the effect of 1 on S(f) remains unchanged, then S(f) will be changed by... Decide; Define a beam scanning linearity parameter L to quantify the linear performance of beam scanning. The calculation formula is as follows: ， The linearity parameter L physically represents the rate of change of the beam scanning rate with frequency; when L = 0, it means that the scanning rate S(f) does not change with frequency and remains constant, at which point the antenna main beam angle θ m It has a strict linear relationship with the operating frequency, which is the ideal linear beam scanning state.

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