Optically transparent vehicle-mounted plane traveling wave end-on-fire antenna

Abstract

The invention discloses an optically transparent vehicle-mounted planar traveling wave end-on-fire antenna, which structurally comprises a feed waveguide, a glass-based medium mirror image waveguide and a transparent wedge-shaped transition layer, wherein the feed waveguide is provided with an electromagnetic wave incident port; the glass-based medium mirror image waveguide is plated with an indium tin oxide (ITO) conductive layer; and the transparent wedge-shaped transition layer is arranged between the feed waveguide and the glass-based medium mirror image waveguide. According to the design, on the premise of keeping high optical transparency, the total attenuation constant caused by traveling wave leakage loss and ITO ohmic loss is reduced by adjusting the thickness of the glass substrate, so that the aperture surface is effectively expanded, and the maximum end-on-fire gain is obtained. Due to the characteristics of light transparency and low profile, the aperture of the antenna can be integrated on the automobile sunroof, and the feed structure of the antenna can be integrated on the sunroof frame. The circulator is connected behind the antenna port to realize isolation of receiving and transmitting channels, during working, electromagnetic waves are fed into the antenna from the excitation port, and then echo signals are reflected and transmitted to a rear signal processor through the circulator. The system detects front obstacles by analyzing echo signals, and then initiative braking early warning is triggered to reduce the rear-end collision risk.

Description

Technical Field

[0001] This invention relates to the field of automotive in-vehicle equipment technology, and in particular to an optically transparent in-vehicle planar traveling wave end-fire antenna that can be discreetly integrated into the sunroof of a car and has vehicle communication and obstacle detection functions. Background Technology

[0002] With the iterative evolution of wireless communication and sensing technologies, the deployment density of wireless front-end devices is increasing. Traditional automotive metal antennas, limited by their inherent physical characteristics, suffer from unavoidable visual obstruction and occupy a significant amount of equipment deployment space. In contrast, transparent antennas, with their excellent light transmittance and conformal properties, can be seamlessly integrated into the transparent structure of vehicle windows, ensuring both the integrity of communication functions and aesthetic appeal.

[0003] Fabricating transparent antennas requires consideration of both the light transmittance of the conductive material and the RF ohmic loss. However, the light transmittance and RF sheet resistance of the conductive thin film are inversely proportional to the film thickness: the thinner the film, the higher the light transmittance, but the higher the RF sheet resistance. The relationship between the light transmittance and RF sheet resistance of the conductive thin film material is a constraint, thus the development of high-gain, high-efficiency optically transparent antennas remains a core challenge. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes an optically transparent vehicle-mounted planar traveling-wave end-fire antenna. This antenna is designed using a glass substrate and an indium tin oxide (ITO) thin film, exhibiting high transparency, high efficiency, and high gain. The antenna combines signal transmission and reception functions, enabling it to detect obstacles by analyzing reflected signals, thereby preventing rear-end collisions.

[0005] The present invention adopts the following technical solution:

[0006] An optically transparent vehicle-mounted planar traveling-wave end-fire antenna is provided. The antenna includes an electromagnetic wave incident port (0), a feed waveguide (1), a transparent wedge-shaped transition layer (2), a transparent dielectric mirror waveguide (3), and a conductive layer (4) at its bottom. The antenna is based on a traveling-wave structure, and its operating mode exhibits low sensitivity to the loss of the transparent conductive material, effectively reducing the impact of the ohmic loss of the transparent conductive material on the antenna performance, thereby realizing a high-gain end-fire radiation mode.

[0007] The antenna adopts an end-fire structure design based on a dielectric mirror waveguide. By adjusting the thickness of the glass substrate, the antenna can be flexibly controlled to minimize the sum of leakage attenuation of the traveling wave mode and attenuation caused by loss of transparent conductive material, thereby expanding the radiation aperture and achieving high-gain end-fire with a gain higher than 12dBi.

[0008] The conductive layer (4) is based on an indium tin oxide (ITO) thin film design, located at the bottom of a transparent dielectric mirror waveguide, and has a sheet resistance of 3Ω / sq. The antenna mode and gain can be adjusted by adjusting the thickness of the glass substrate on the ITO thin film.

[0009] The feeding waveguide (1) and the transparent wedge transition layer (2) are combined to form an excitation waveguide. The excitation waveguide is welded to the edge of the car sunroof as an antenna feeding structure. A circulator is connected after the excitation port of the excitation waveguide to achieve isolation of the transmit and receive channels.

[0010] The transparent wedge-shaped transition layer is used to improve the impedance matching of the antenna, enhance the efficiency and stability of signal transmission, and the wedge structure can reduce wind resistance when the car is driving at high speed.

[0011] The antenna body is made of glass and is integrated with the car sunroof during manufacturing. The glass is coated with ITO by magnetron sputtering. The thickness of the end-fire antenna is only 1.82 mm, and the electrical dimension at the operating frequency of 8.5 GHz is 0.05 times the wavelength, which has low profile characteristics.

[0012] The antenna has a transparency of more than 80%;

[0013] The thickness of the structure composed of the transparent wedge transition layer (2) and the transparent dielectric mirror waveguide (3) is the optimal thickness, and the corresponding radiation loss and attenuation caused by ITO ohmic loss are the smallest, which has good radiation performance.

[0014] Transparent dielectric mirror waveguides employ a thin-thickness structure, where the electric field of electromagnetic waves is located in the air outside the dielectric during propagation, thus suppressing attenuation caused by ohmic losses of the transparent material.

[0015] The transparent antenna is an end-fire antenna, which can be deployed in a car sunroof to provide better signal coverage and communication performance without taking up too much space. The size of the glass sunroof where the antenna is installed does not affect the end-fire attribute of the antenna, ensuring the robustness of the antenna's performance on different carrier platforms.

[0016] The antenna is used to detect obstacles in front of and behind the vehicle to prevent rear-end collisions.

[0017] The antenna includes a feed waveguide (1) with an electromagnetic wave incident port (0); a radiating layer with high optical transparency, including a transparent dielectric mirror waveguide (3) with a thin conductive layer (4) at the bottom; the feed waveguide forms a smooth transition connection with the top of the radiating layer through a transparent wedge-shaped transition layer (2), and the radiating layer is deployed in the curved area of ​​the car sunroof, so that the car sunroof has the wireless communication function of the antenna while maintaining the transparency of the view.

[0018] The radiating layer is a conformal integrated structure based on an ITO thin film and a transparent dielectric substrate. The feeding waveguide and the wedge-shaped transition layer form an excitation waveguide. The excitation waveguide is welded to the edge of the car sunroof.

[0019] A circulator is connected to the excitation port of the excitation waveguide, and the non-reciprocal characteristic of the circulator is used to achieve isolation between the transmit and receive channels of the antenna.

[0020] The antenna is connected to the vehicle's onboard system. The wedge-shaped transition layer can effectively reduce the wind resistance of the vehicle at high speeds. The radiating layer is integrated into the curved area at the front or rear of the sunroof of the vehicle with its bottom curved surface. The radiating layer uses a thin transparent dielectric mirror waveguide so that its working electric field mainly exists in the air outside the dielectric, thereby reducing the dielectric ohmic loss of electromagnetic waves.

[0021] When the antenna is working, the electromagnetic waves generated by the vehicle system are fed into the antenna from the excitation port and radiate in front of the car. The reflected echo signals generated by the obstacles are transmitted to the signal processor of the vehicle system through the circulator. The vehicle system analyzes the echo signals and reconstructs the distance and relative speed of the obstacles in front of the car in real time. It then triggers active braking warning to reduce the risk of rear-end collisions during the car's driving process.

[0022] The antenna body consists of a transparent dielectric mirror waveguide, its bottom conductive layer, and a transparent wedge-shaped transition layer. The antenna body and the car sunroof are integrated into a single structure through an integrated processing procedure. In this integrated processing procedure, ITO coating is applied to the transparent area of ​​the antenna body using magnetron sputtering.

[0023] The transparent dielectric mirror waveguide is used for leakage wave radiation and uses soda-lime glass as the dielectric.

[0024] The conductive layer is a thin-film structure based on ITO film, which is located at the bottom of the transparent dielectric mirror waveguide. The thickness of the transparent dielectric mirror waveguide is the optimal thickness that minimizes the radiation loss and the ohmic loss caused by ITO.

[0025] The transparent wedge-shaped transition layer uses quartz glass as the medium.

[0026] The antenna has a transparency of more than 80%.

[0027] The antenna gain is adjusted by changing the thickness or size of the transparent dielectric mirror waveguide.

[0028] The antenna is a transparent antenna based on a traveling wave structure design, which can avoid strong resonance and improve the antenna's gain and efficiency.

[0029] The antenna is a transparent end-fire antenna, which is deployed and integrated into the sunroof of the car to optimize the antenna's signal coverage and communication performance while reducing space occupation.

[0030] This invention proposes an optically transparent vehicle-mounted planar traveling-wave end-fire antenna. Its structural configuration includes: a feed waveguide with an electromagnetic wave incident port, a transparent wedge-shaped transition layer for impedance matching between the waveguide and the radiating layer, and a transparent dielectric mirror waveguide with a conductive layer. The antenna is based on a glass substrate and an indium tin oxide (ITO) conductive thin film. While maintaining high optical transparency, the antenna effectively reduces the total attenuation constant caused by power leakage loss and ITO ohmic loss by adjusting the thickness of the glass substrate, thereby effectively expanding the aperture and achieving maximum end-fire gain. Due to its optical transparency and low profile, the antenna aperture can be integrated into a car sunroof, and the antenna feed structure can be integrated into the sunroof frame. A circulator is connected to the antenna port to achieve transmit / receive channel isolation: electromagnetic waves are fed into the antenna from the excitation port, and the reflected echo signal is transmitted to the rear signal processor through the circulator. The system analyzes the echo signal to detect obstacles ahead, thereby triggering active braking warning to reduce the risk of rear-end collisions.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. The optically transparent vehicle-mounted planar traveling wave end-fire antenna of the present invention has a thin thickness, achieving high transparency, and has the advantages of simple structure, low profile, and high gain.

[0033] 2. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna of this invention is designed based on a traveling-wave structure, balancing antenna efficiency and gain. This invention can be integrated into a car sunroof, and a circulator connected after the excitation port can extract the received reflected signal to analyze information about obstacles ahead, reducing the probability of rear-end collisions.

[0034] 3. The transparent antenna of the present invention is integrally formed with the sunroof of the car, and the feeding structure on the side of the antenna is fixed to the side of the sunroof by welding, thereby avoiding drilling or other destructive installation at the sunroof. Attached Figure Description

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] Appendix Figure 1 This is a structural diagram of an optically transparent vehicle-mounted planar traveling wave end-fire antenna proposed in this invention;

[0037] Appendix Figure 2 This is a transmittance curve of the aperture of the optically transparent antenna proposed in this invention;

[0038] Appendix Figure 3 This is a schematic diagram of the deployment method and circulator transceiver setup of the vehicle-mounted optical transparent antenna proposed in this invention;

[0039] Appendix Figure 4This invention presents the gain patterns of the optically transparent vehicle-mounted planar traveling wave end-fire antenna at a frequency of 8.5 GHz in the yoz and xoy planes.

[0040] Appendix Figure 5 This is a curve showing the normalized phase constant of the optically transparent high-gain vehicle-mounted planar traveling-wave end-fire antenna proposed in this invention as a function of glass substrate thickness (the relationship between antenna phase constant and glass layer thickness at 8.5 GHz frequency).

[0041] Appendix Figure 6 This is a graph showing the gain and directivity of the optically transparent high-gain vehicle-mounted planar traveling wave end-fire antenna proposed in this invention as a function of glass substrate thickness (relationship between antenna gain and directivity as a function of glass layer thickness at 8.5 GHz frequency).

[0042] Appendix Figure 7 This is a curve showing the normalized attenuation constant of the optically transparent high-gain vehicle-mounted planar traveling wave end-fire antenna proposed in this invention as a function of glass substrate thickness under different ITO sheet resistance conditions (the relationship between the normalized attenuation constant and glass layer thickness at a frequency of 8.5GHz under different ITO sheet resistance conditions).

[0043] In the diagram: 0 - Electromagnetic wave incident port; 1 - Feed waveguide; 2 - Transparent wedge transition layer; 3 - Transparent dielectric mirror waveguide; 4 - Conductive layer. Detailed Implementation

[0044] To further illustrate, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples:

[0045] As shown in the figure, an optically transparent vehicle-mounted planar traveling-wave end-fire antenna includes an electromagnetic wave incident port 0, a feed waveguide 1, a transparent wedge-shaped transition layer 2, a transparent dielectric mirror waveguide 3, and a conductive layer 4 at its bottom. The antenna is based on a traveling-wave structure, and its operating mode exhibits low sensitivity to the loss of the transparent conductive material, effectively reducing the impact of the ohmic loss of the transparent conductive material on the antenna performance, thereby achieving a high-gain end-fire radiation mode.

[0046] The antenna adopts an end-fire structure design based on a dielectric mirror waveguide. By flexibly adjusting the thickness of the glass substrate, the sum of leakage attenuation of the traveling wave mode and attenuation caused by loss of transparent conductive material is minimized, thereby expanding the radiation aperture and achieving high-gain end-fire with a gain higher than 12dBi.

[0047] The conductive layer 4 is based on an indium tin oxide (ITO) thin film design and is located at the bottom of the transparent dielectric mirror waveguide. Its sheet resistance is 3Ω / sq, and the antenna mode and gain can be adjusted by adjusting the thickness of the glass substrate on the ITO thin film.

[0048] The feeding waveguide 1 and the transparent wedge transition layer 2 constitute the excitation waveguide. The excitation waveguide is welded to the edge of the car sunroof as an antenna feeding structure. A circulator is connected after the excitation port of the excitation waveguide to achieve isolation of the transmit and receive channels.

[0049] The transparent wedge-shaped transition layer is used to improve the impedance matching of the antenna, enhance the efficiency and stability of signal transmission, and the wedge structure can reduce wind resistance when the car is driving at high speed.

[0050] The antenna body is made of glass and is integrated with the car sunroof during manufacturing. The glass is coated with ITO by magnetron sputtering. The thickness of the end-fire antenna is only 1.82 mm, and the electrical dimension at the operating frequency of 8.5 GHz is 0.05 times the wavelength, which has low profile characteristics.

[0051] The antenna has a transparency of more than 80%;

[0052] The structure composed of the transparent wedge transition layer 2 and the transparent dielectric mirror waveguide 3 has the optimal thickness, resulting in the minimum radiation loss and attenuation caused by ITO ohmic loss, and thus exhibits good radiation performance.

[0053] Transparent dielectric mirror waveguides employ a relatively thin structure, and during the propagation of electromagnetic waves, the electric field is mainly distributed in the air outside the dielectric to suppress the attenuation caused by the ohmic loss of the transparent material.

[0054] The transparent antenna is an end-fire antenna, which can be deployed in a car sunroof to provide better signal coverage and communication performance without taking up too much space. The size of the glass sunroof where the antenna is installed does not affect the end-fire attribute of the antenna, ensuring the robustness of the antenna's performance on different carrier platforms.

[0055] The antenna is used to detect obstacles in front of and behind the vehicle to prevent rear-end collisions.

[0056] An optically transparent vehicle-mounted planar traveling-wave end-fire antenna includes a radiating layer with high optical transparency and a feed waveguide 1 with an electromagnetic wave incident port 0; the radiating layer includes a transparent dielectric mirror waveguide 3 with a thin conductive layer 4 at the bottom; the feed waveguide is smoothly connected to the top of the radiating layer by a transparent wedge-shaped transition layer 2, and the radiating layer is deployed in the curved area of ​​a car sunroof so that the car sunroof has wireless communication capabilities while maintaining visual transparency.

[0057] The radiating layer is a conformal integrated structure based on an ITO thin film and a transparent dielectric substrate. The feed waveguide and the wedge-shaped transition layer constitute the excitation waveguide. The excitation waveguide is welded to the edge of the car sunroof to form the antenna feed structure.

[0058] A circulator is connected to the excitation port of the excitation waveguide, and the non-reciprocal characteristic of the circulator is used to achieve isolation between the transmit and receive channels of the antenna.

[0059] The antenna is connected to the vehicle's onboard system. The wedge-shaped transition layer adopts a shape structure that can effectively reduce the wind resistance of the vehicle at high speeds. The radiating layer is integrated into the curved area at the front or rear of the sunroof of the vehicle with its bottom curved surface. The radiating layer uses a thin-layer transparent dielectric mirror waveguide so that its working electric field mainly exists in the air outside the dielectric, thereby reducing the dielectric ohmic loss of electromagnetic waves.

[0060] When the antenna is working, the electromagnetic waves generated by the vehicle system are fed into the antenna from the excitation port and radiated in front of the car. The resulting reflected echo signal is transmitted to the signal processor of the vehicle system through the independent receiving port of the circulator. The vehicle system analyzes the echo signal and reconstructs the distance and relative speed of obstacles in front of the car in real time, so as to reduce the risk of rear-end collisions during the car driving by triggering active braking warning.

[0061] The antenna body consists of a transparent dielectric mirror waveguide, its bottom conductive layer, and a transparent wedge-shaped transition layer. The antenna body and the car sunroof are integrated into a single structure through an integrated processing procedure. In this integrated processing procedure, ITO coating is applied to the transparent area of ​​the antenna body using magnetron sputtering.

[0062] The transparent dielectric mirror waveguide is used for leakage wave radiation and uses soda-lime glass as the dielectric.

[0063] The conductive layer is a thin-film structure based on ITO film, which is located at the bottom of the transparent dielectric mirror waveguide. The thickness of the transparent dielectric mirror waveguide is the optimal thickness that minimizes the radiation loss and the ohmic loss caused by ITO.

[0064] The transparent wedge-shaped transition layer uses quartz glass as the medium.

[0065] The antenna has a transparency range greater than 80%.

[0066] The antenna is a transparent antenna based on a traveling wave structure. Its design based on the traveling wave structure avoids strong resonance and improves the antenna's gain and efficiency.

[0067] The antenna is a transparent end-fire antenna, which is deployed and integrated into the sunroof of the car to optimize the antenna's signal coverage and communication performance while reducing space occupation.

[0068] Example:

[0069] In this example, Figure 1 The present invention proposes an optically transparent vehicle-mounted planar traveling-wave end-fire antenna. It includes a feed waveguide 1 with an electromagnetic wave incident port 0, a transparent wedge-shaped transition layer 2, a transparent dielectric mirror waveguide 3, and a thin conductive layer 4 at its bottom.

[0070] The transmittance of this product in the visible spectrum is greater than 80%, such as Figure 2 As shown.

[0071] The feed waveguide 1 in the example has a width w2 = 42 mm, a length l1 = 24 mm, and a height h1 = 5.32 mm.

[0072] The transparent wedge-shaped transition layer in the example has a length of l2 = 44 mm, a width of w1 = 66 mm, and a thickness of h1 = 3.5 mm. The dielectric material is quartz glass with a relative permittivity of 3.78 and a loss tangent of 0.0001.

[0073] The transparent dielectric mirror waveguide 4 in this example has an overall length l3 = 250 mm, a width w3 = 300 mm, and a thickness h2 = 1.82 mm. Its thinner bottom conductive layer has a width w2 = 42 mm and a length l4 = 218 mm. The transparent dielectric mirror waveguide 3 uses soda-lime glass as the dielectric, with a relative permittivity of 7.25 and a loss tangent of 0.001. The conductive layer is based on an ITO thin film design with a sheet resistance of 3 Ω / sq. The use of a thin transparent dielectric and transparent conductive oxide allows the antenna to have a transparency of over 80%, meeting the requirement of application in automotive glass without obstructing the view of occupants.

[0074] In this example, the transparent wedge-shaped transition layer 2 is placed above the transparent dielectric mirror waveguide 4, and the conductive layer 4 is located at the bottom of the transparent dielectric mirror waveguide 4. Electromagnetic waves are fed into the feed waveguide from the electromagnetic wave incident port 0, and then propagate to the transparent wedge structure, the transparent dielectric mirror waveguide 3, and the thinner ITO conductive layer 4 at its bottom, and radiate.

[0075] The antenna described is a leaky wave antenna, employing a wedge-shaped structure to improve impedance matching. The traveling wave structure avoids localized electromagnetic field concentration, reducing losses caused by the transparent conductive material and thus improving antenna efficiency and gain. Furthermore, the thin conductive layer at the bottom of the transparent dielectric mirror waveguide, based on ITO material, effectively enhances the antenna's front-to-back ratio.

[0076] The proposed antenna can achieve lower attenuation by optimizing the thickness of the transparent dielectric mirror waveguide. When the dielectric is thick, it exhibits a strong field confinement effect, leading to poor antenna radiation performance; conversely, excessively thin dielectric significantly weakens the electromagnetic field confinement, resulting in substantial radiation loss. Therefore, selecting a dielectric waveguide of suitable thickness, with a phase constant greater than but close to the wavenumber in vacuum, satisfies the Hansen-Woodyard condition, thus forming a highly directional end-fire array. End-fire antennas offer the advantages of high efficiency and high gain.

[0077] In this example, the antenna operates at a wavelength of 35 mm (corresponding to a frequency of 8.5 GHz). When electromagnetic waves are fed from the incident port 0, the electric field component of the antenna is perpendicular to the antenna and pointing upwards, while the magnetic field is along the wide side of the dielectric (along the positive x-direction). In this example, the thickness of the transparent antenna is h2 = 1.82 mm, and the electrical dimension corresponding to the operating frequency of 8.5 GHz is 0.05λ. The electric field mainly exists in the air outside the antenna, which greatly reduces the dielectric loss of the antenna.

[0078] The optically transparent antenna in this example is based on a traveling wave structure design, thus exhibiting high gain. Simulation results show that the antenna gain is greater than 11.5 dBi in the 8-9 GHz range, with a peak gain of 13.3 dBi. The two-dimensional radiation pattern of the antenna at 8.5 GHz is shown below. Figure 2 As shown, the left figure is the radiation pattern of the antenna in the xoy plane, and the right figure is the radiation pattern of the antenna in the yoz plane.

[0079] This example demonstrates how to precisely control the antenna gain by adjusting the thickness and size of the medium to meet the requirements of different communication needs. Figure 3 The antenna phase constant is extracted at a fixed frequency of 8.5 GHz, and the discussion is based on this frequency for different glass layer thicknesses h. Figure 4 As can be seen, when the antenna operates at 8.5 GHz, regardless of whether the dielectric thickness is greater than or less than 1.82 mm, the antenna gain decreases with changes in dielectric thickness. The underlying mechanism is that excessively thin or thick glass layers lead to a relatively high total attenuation constant; for example... Figure 5 As shown, when the dielectric thickness is large, the surface current density increases due to the strong field confinement effect near ITO, leading to a significant increase in ohmic loss. Conversely, when the dielectric thickness is too thin, the field confinement effect of the dielectric substrate weakens, causing electromagnetic energy to dissipate rapidly into free space, resulting in substantial ohmic loss. Therefore, a dielectric thickness of 1.82 mm corresponds to the smallest total attenuation constant, achieving the best radiation performance.

[0080] In summary, this example provides an optically transparent vehicle-mounted planar traveling-wave end-fire antenna. The antenna includes a feed waveguide with an electromagnetic wave incident port, a transparent wedge-shaped transition layer, a transparent dielectric mirror waveguide, and a conductive layer. During operation, the antenna's traveling-wave structure design reduces the loss caused by the transparent conductive material, resulting in high efficiency and gain. Due to the antenna's thinness, the electric field component of the electromagnetic wave primarily exists in the air outside the dielectric during propagation, reducing dielectric loss. By adjusting the dielectric thickness, the phase constant of the dielectric waveguide is adjusted so that the antenna's phase constant at different frequencies is greater than but close to the wavenumber in vacuum; in this case, the antenna's radiation mode is end-fire mode.

[0081] This example demonstrates an end-fire antenna design based on a traveling wave structure, achieving a balance between efficiency and gain while maintaining high transparency. The antenna also boasts a simple structure and low profile. A circulator connected to the antenna's excitation port allows for analysis of the received reflected signal to identify obstacles ahead. Furthermore, the antenna's high gain enables precise distance measurements when used for vehicle communication and obstacle detection, reducing the probability of rear-end collisions.

Claims

1. An optically transparent vehicle-mounted planar traveling-wave end-fire antenna, characterized in that: The antenna includes an electromagnetic wave incident port (0), a feed waveguide (1), a transparent wedge transition layer (2), a transparent dielectric mirror waveguide (3), and a conductive layer (4) at its bottom; the antenna is based on a traveling wave structure, and its operating mode exhibits low sensitivity to the loss of transparent conductive materials.

2. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 1, characterized in that: The antenna adopts an end-fire structure design based on a dielectric mirror waveguide. By adjusting the thickness of the glass substrate, the sum of leakage attenuation of the traveling wave mode and attenuation caused by loss of transparent conductive material is minimized, and the radiation aperture is expanded to achieve high-gain end-fire with a gain higher than 12dBi.

3. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 1, characterized in that: The conductive layer (4) is based on an indium tin oxide (ITO) thin film design and is located at the bottom of a transparent dielectric mirror waveguide. The antenna mode and gain are controlled by adjusting the thickness of the glass substrate on the ITO thin film.

4. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 1, characterized in that: The feeding waveguide (1) and the transparent wedge transition layer (2) constitute the excitation waveguide. The excitation waveguide is welded to the edge of the car sunroof, and its excitation port is connected to a circulator to achieve isolation of the transmit and receive channels.

5. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 1, characterized in that: The transparent wedge-shaped transition layer is used to improve the impedance matching of the antenna, enhance the efficiency and stability of signal transmission, and reduce wind resistance of the car at high speeds due to its wedge structure.

6. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 1, characterized in that: The antenna body is made of glass and is integrated with the car sunroof during manufacturing. The glass is coated with ITO by magnetron sputtering. At the operating frequency of 8.5 GHz, the thickness of the end-fire antenna is 0.05 times the wavelength, which has low profile characteristics.

7. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 1, characterized in that: The antenna has a transparency of more than 80%; The structure composed of the transparent wedge transition layer (2) and the transparent dielectric mirror waveguide (3) has the smallest attenuation caused by radiation loss and ITO ohmic loss corresponding to its thickness; Transparent dielectric mirror waveguides have a thin thickness, and during the propagation of electromagnetic waves, the main electric field is located in the air outside the dielectric to suppress the attenuation caused by the ohmic loss of the transparent material. The transparent antenna is deployed as an end-fire antenna in the sunroof of the car, and the size of the sunroof does not affect the end-fire properties of the antenna. The antenna is used to detect obstacles in front of and behind the vehicle, reducing the risk of rear-end collisions during vehicle operation.

8. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 1, characterized in that: The antenna includes a feed waveguide (1) with an electromagnetic wave incident port (0); a radiating layer with high optical transparency, including a transparent dielectric mirror waveguide (3) with a thin conductive layer (4) at the bottom; the feed waveguide forms a smooth transition connection with the top of the radiating layer through a transparent wedge-shaped transition layer (2), the radiating layer being deployed in the curved area of ​​the car sunroof so that the car sunroof has the radiating function of the antenna while maintaining visual transparency; The radiating layer is a conformal integrated structure based on ITO thin film and glass substrate. The feed waveguide and wedge transition layer are combined to form the excitation waveguide. The excitation waveguide is welded to the edge of the car sunroof, and its excitation port is connected to a circulator. The non-reciprocity characteristic of the circulator is used to achieve isolation of the antenna's transmit and receive channels. The antenna is connected to the vehicle's onboard system. The wedge-shaped transition layer can effectively reduce the wind resistance of the vehicle at high speeds. The radiating layer is integrated into the curved area at the front or rear of the sunroof of the vehicle with its bottom curved surface. The radiating layer uses a thin transparent dielectric mirror waveguide to make its working electric field mainly exist in the air outside the dielectric, so as to reduce the dielectric ohmic loss of electromagnetic waves.

9. The optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 8, characterized in that: When the antenna is working, the electromagnetic waves generated by the vehicle system are fed into the antenna from the excitation port and radiated in front of the car. The resulting reflected echo signal is transmitted to the signal processor of the vehicle system through the independent receiving port of the circulator. The vehicle system analyzes the echo signal and reconstructs the distance and relative speed of obstacles in front of the car in real time, so as to reduce the risk of rear-end collisions during the car driving by triggering active braking warning.

10. An optically transparent vehicle-mounted planar traveling-wave end-fire antenna according to claim 9, characterized in that: The transparent dielectric mirror waveguide, its bottom conductive layer, and the transparent wedge-shaped transition layer constitute the antenna body. The antenna body and the car sunroof are formed into an integrated structure through an integrated processing process. In the integrated processing process, ITO coating is applied to the transparent area of ​​the antenna body using magnetron sputtering. The transparent dielectric mirror waveguide is used for leakage wave radiation and uses soda-lime glass as the dielectric. The conductive layer is a thin-film structure based on ITO film, which is located at the bottom of the transparent dielectric mirror waveguide. The thickness of the transparent dielectric mirror waveguide is the optimal thickness that minimizes the radiation loss and the ohmic loss caused by ITO. The transparent wedge-shaped transition layer uses quartz glass as the medium; The antenna has a transparency greater than 80%; The antenna gain is adjusted by adjusting the thickness or size of the transparent dielectric mirror waveguide; The antenna is a transparent antenna based on a traveling wave structure. Its design based on the traveling wave structure avoids strong resonance and improves the antenna's gain and efficiency. The antenna is a transparent end-fire antenna, which is deployed and integrated into the sunroof of the car to optimize the antenna's signal coverage and communication performance while reducing space occupation.

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