Waveguide integrated terahertz wave radar

Abstract

The present application relates to the technical field of terahertz wave radar, in particular to a waveguide integrated terahertz wave radar. The terahertz wave radar adopts a low-loss flexible terahertz wave waveguide tube as a signal transmission pipeline; the preparation method of the low-loss flexible terahertz wave waveguide tube comprises the following steps: S1: activating the inner wall of a polymer matrix tube; S2: modifying the inner wall by amino silane coupling agent; S3: depositing a silver plating layer on the inner wall through a silver mirror reaction. The terahertz wave radar comprises a central processing unit, a low-loss terahertz wave waveguide network and a plurality of remote antenna arrays; the present application adopts a terahertz wave waveguide as a signal transmission pipeline, the medium loss is extremely low, and the detection distance and precision of the radar are improved. Moreover, the closed structure of the waveguide has excellent shielding performance, the system is more stable, and it is more convenient to perform maintenance, system updating and heat dissipation arrangement.

Description

Technical Field

[0001] This invention relates to the field of terahertz wave radar technology, specifically a waveguide-integrated terahertz wave radar. Background Technology

[0002] Radar is an electronic device used for detection, location, and identification, with wide applications in transportation, meteorology, military, aerospace, and other fields. Radar bands are specific ranges defined by electromagnetic wave frequency or wavelength. Different bands have unique propagation characteristics, penetration capabilities, and application scenarios. For example, the mainstream automotive radar currently uses millimeter-wave radar, which operates in the millimeter-wave frequency band (30-300 GHz, wavelength 1-10 mm). This frequency range provides good resolution and accuracy, is minimally affected by the environment, and has strong nighttime penetration capabilities, making it suitable for collision avoidance, adaptive cruise control, blind spot detection, in-vehicle detection, and side-attack warning.

[0003] To achieve multi-directional detection, the traditional radar integration method is the integrated chip solution, which involves installing integrated chips in various directions on the same body. An integrated chip solution integrates the radio frequency front-end and the digital processing core into a single chip. This approach requires multiple independent integrated radars and multiple computing chips, and it suffers from the following problems:

[0004] 1) High cost: Each radar is equipped with a complete computing chip (MCU / DSP) and power supply and interface circuits. Currently, a smart car needs to deploy 5-8 radars, which results in a huge waste of computing power and duplication of hardware costs.

[0005] 2) Difficulty in hardware updates: The radar's perception algorithm is embedded in its own computing chip. To upgrade the algorithm, the firmware of each radar must be updated separately, and the limited computing power may even prevent it from supporting complex new algorithms.

[0006] 3) Difficult heat dissipation layout: Since each radar is a heat source, densely arranged in a small space (such as rearview mirrors and bumpers) makes heat dissipation design complicated.

[0007] Therefore, there is an urgent need for a flexible waveguide vehicle-mounted radar that adopts a new integrated approach, and that achieves cost reduction, easy installation, disassembly and upgrading, and simple heat dissipation arrangement. Summary of the Invention

[0008] One of the objectives of this invention is to overcome the shortcomings of the prior art and provide a waveguide-integrated terahertz wave radar, so as to at least achieve the effects of reducing costs, reducing the difficulty of equipment upgrades, and simplifying heat dissipation arrangements.

[0009] The objective of this invention is achieved through the following technical solution: A waveguide-integrated terahertz wave radar uses a low-loss flexible terahertz waveguide as a signal transmission channel. The method for fabricating the low-loss flexible terahertz waveguide includes the following steps: S1: Activate the inner wall of the polymer matrix tube; S2: The inner wall is modified by amylation using an aminosilane coupling agent; S3: A silver plating layer is deposited on the inner wall by a silver mirror reaction.

[0010] In some embodiments, in step S1, the polymer matrix tube includes a polycarbonate tube, a polyimide tube, a polyethylene terephthalate tube, a nylon tube, a polyetheretherketone tube, and a polyurethane tube.

[0011] In some embodiments, in step S2, the aminosilane coupling agent includes KH550 and KH792.

[0012] In some embodiments, the density of the silver plating is controlled by adjusting the amination modification time; the thickness of the silver plating is controlled by adjusting the silver mirror reaction time.

[0013] In some examples, the amination modification time is 15-20 min; and / or, the silver mirror reaction time is 5-6 min.

[0014] In some embodiments, the terahertz radar is mounted on a vehicle and wired inside the vehicle's fuselage. It can be applied in military, transportation, meteorological, and aerospace fields.

[0015] The second objective of this invention is to provide a vehicle-mounted waveguide-integrated terahertz wave radar: The vehicle-mounted radar uses a low-loss flexible terahertz waveguide as a signal transmission channel for wiring inside the vehicle, including a central processing unit, a low-loss terahertz waveguide network, and several remote antenna arrays. The central processing unit includes a signal transceiver module, a signal conversion module, and a digital processing component. The remote antenna array includes a remote transmitting antenna array and a remote receiving antenna array; The central processing unit is connected to each remote antenna array via a low-loss flexible terahertz waveguide. The low-loss terahertz wave network consists of several low-loss flexible terahertz waveguides embedded in the vehicle body. In some embodiments, the signal transceiver module is used to generate frequency-modulated continuous wave signals and receive echo signals, including a signal transmission channel, a signal reception channel, and a signal source.

[0016] In some examples, the signal source is an FMCW signal source.

[0017] In some embodiments, the signal conversion module is used to convert the echo signal into a digital signal, including a mixer and an A / D converter.

[0018] In some embodiments, the digital processing component is used to process the digital signal and calculate and output the target distance, including a conventional vehicle-mounted MCU or a dedicated radar processor.

[0019] In some embodiments, the remote transmitting antenna array includes at least one transmitting antenna; the remote receiving antenna array includes at least one receiving antenna, and a low-noise amplifier (LNA) integrated with or cascaded with the receiving antenna.

[0020] In some embodiments, the low-loss flexible terahertz waveguide is embedded in the structural cavity of the A-pillar, roof beam, or bumper anti-collision beam of the vehicle body.

[0021] In some embodiments, the vehicle-mounted radar further includes a command input / output device for inputting commands and outputting distance results; the input / output device transmits digital signals to the central processing unit via a data line.

[0022] In some examples, the input / output module includes at least a CAN FD transceiver, an in-vehicle smart computer, or a mobile app; In some embodiments, the number of signal transceiver modules corresponds to the number of remote antenna arrays; the number of signal conversion modules and digital processing components is one each.

[0023] In some embodiments, each of the remote antenna arrays is connected to the central processing unit via two independent low-loss flexible terahertz waveguides; one of which is connected to the signal transmission channel and the other is connected to the signal reception channel.

[0024] It is worth noting that in traditional automotive millimeter-wave radar integration solutions, the high transmission loss of the high-frequency radio frequency signals transmitted and received by the radar antenna in the coaxial cable, coupled with the large volume of raw data, fundamentally limits system design. Therefore, traditional solutions necessitate placing the signal processing unit at the front end: the radio frequency echo signal must be down-converted and converted from analog to digital at each radar node before being transmitted to the processor. This leads to hardware redundancy, increased costs, and difficulties in upgrading. Furthermore, to reduce the pressure on the central processing unit's bandwidth and improve response speed, mainstream solutions further integrate computing chips at each radar node, performing perception calculations locally and only uploading the results.

[0025] Millimeter-wave radar refers to radar devices operating at frequencies between 30 and 300 GHz. This band has a wide range, but commonly used millimeter-wave radar frequencies are generally between 76 and 79 GHz. This is mainly a result of a trade-off between performance, cost, regulations, and the maturity of the industry chain. Pursuing higher frequencies brings a series of technical challenges. For example, terahertz radar refers to radar operating at frequencies of 0.1 to 10 THz. Its accuracy is more than 20% higher than that of millimeter-wave radar. However, due to the more bulky and difficult-to-integrate hardware components of terahertz radar, such as core radio frequency hardware, and the significantly increased transmission loss of terahertz waves, its development in the automotive field is limited.

[0026] This invention fundamentally overcomes the aforementioned limitations by providing a flexible terahertz waveguide with extremely low transmission loss. Its flexible structure is suitable for embedding within a vehicle body, while the extremely low transmission loss in the terahertz band enables long-distance, high-fidelity transmission of high-frequency analog radio frequency signals. This makes a true 'satellite-like' integrated architecture possible: a single centralized high-performance signal processing unit can process raw signals from all distributed antenna arrays, eliminating the need for integrated terahertz radar equipment. This overcomes the disadvantages of large size and difficulty in integration associated with terahertz radar, thereby reducing system costs, optimizing computing resources, and unifying and upgrading global perception algorithms.

[0027] The beneficial effects of this invention are: 1. This invention adopts a satellite-style architecture, eliminating the need for multiple integrated radars. It replaces multiple distributed, low-computing-power chips with a single powerful central processing unit (CPU), significantly reducing hardware costs, improving resource utilization, and optimizing the space layout of the radar system. When the algorithm needs updating, only the CPU needs to be updated, and the heat dissipation system only needs to consider this single heat source. This radar can be applied in various fields such as military, transportation, meteorology, and aerospace.

[0028] 2. The low-loss flexible terahertz waveguide of this invention uses an aminosilane coupling agent to replace the traditional palladium-based activation, forming Si-OC chemical bonds on the inner wall of polymers such as polycarbonate, and introducing amino groups (-NH2). During the silver mirror reaction, some silver ions in the silver ammonia solution will form coordination bonds when they come into contact with -NH2, reducing costs and environmental risks, while significantly improving the bonding force between the silver layer and the polymer matrix, avoiding problems such as silver film peeling and excessive roughness.

[0029] 3. The low-loss flexible terahertz waveguide of this invention has a surface roughness Ra of less than 12nm, which meets the skin depth requirement; its length can reach 8 meters, which has the potential for industrial application; its transmission loss at 220 GHz can reach 0.73 dB / m, which is close to the theoretical calculation value (0.68 dB / m), and its performance is better than most existing flexible waveguides; even with a bending radius of 20 cm, the transmission loss is still kept below 0.9 dB / m, which meets the application requirements of flexibility and miniaturization.

[0030] 4. This invention also provides a vehicle-mounted radar device that uses a terahertz waveguide as the signal transmission channel and air as the medium. Compared to traditional coaxial cables, the dielectric loss is extremely low, resulting in a high signal-to-noise ratio even in the terahertz frequency band, thus improving the radar's detection range and accuracy. Furthermore, the waveguide's enclosed structure provides excellent shielding, virtually eliminating signal leakage and external interference, leading to a more stable system. While mainstream millimeter-wave vehicle-mounted radars typically operate at around 77GHz, the current trend is towards higher frequencies. The main advantages of higher frequencies over lower frequencies are significantly higher bandwidth and resolution, faster transmission rates, smaller antenna size, and stronger anti-interference capabilities. The waveguide used in this invention exhibits extremely low transmission loss in the 220GHz terahertz wave band, approaching the simulation limit, making it highly suitable as a waveguide for this scenario for long-distance transmission.

[0031] 5. The low-loss flexible waveguide integrated vehicle radar of this invention, because it does not use an integrated radar and the waveguide uses in-vehicle wiring, requires fewer heat dissipation devices, greatly optimizing vehicle space. Therefore, it can accommodate a larger number of antenna arrays and can be applied to various scenarios. In addition to external distance measurement, driver assistance, and obstacle perception, it can also be applied to in-vehicle scenarios, such as in-vehicle monitoring and detection of missing pets or children. Attached Figure Description

[0032] Figure 1 The images shown are SEM images and nucleation methods of silver deposition in Embodiment 1, Comparative Examples 1 and 3 of the present invention; wherein, a and b are SEM images and nucleation methods of Comparative Example 1, c and d are SEM images and nucleation methods of Embodiment 1, and e and f are SEM images and nucleation methods of Comparative Example 3.

[0033] Figure 2 The images show a comparison of SEM images of low-loss flexible terahertz waveguides in Embodiments 1, 3, 4, and 5 of the present invention; wherein, a is the SEM image of Embodiment 1, b is the SEM image of Embodiment 3, c is the SEM image of Comparative Example 4, and f is the SEM image of Comparative Example 5.

[0034] Figure 3The AFM diagrams of the low-loss flexible terahertz waveguides in Embodiments 1-2 and Comparative Examples 1-3 and 5 of the present invention are compared; where a is the AFM diagram of Comparative Example 1, b is the AFM diagram of Comparative Example 2, c is the AFM diagram of Embodiment 1, d is the AFM diagram of Embodiment 2, e is the AFM diagram of Comparative Example 3, and f is the AFM diagram of Comparative Example 5.

[0035] Figure 4 The image shows the FTIR detection spectrum of the low-loss flexible terahertz wave hollow waveguide of Embodiment 1 of the present invention.

[0036] Figure 5 This is the XPS detection spectrum of the low-loss flexible terahertz wave hollow waveguide of Embodiment 1 of the present invention.

[0037] Figure 6 The results of the cross-cut test in Experimental Example 3 of the present invention are shown in Figure a, where a is the cross-cut test result of silver plating using the conventional palladium-based activation method, and b is the cross-cut test result of silver plating modified with aminosilane according to the present invention.

[0038] Figure 7 This is a schematic diagram of the vehicle-mounted radar device of the present invention.

[0039] Among them, 1-dry remote antenna array, 2-low-loss terahertz waveguide network, 3-central processing unit, 4-input and output devices. Detailed Implementation

[0040] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0041] Example 1 This embodiment provides a low-loss flexible waveguide integrated vehicle radar device to realize intelligent driving functions, as detailed below: refer to Figure 7 It includes four input / output devices 4 (domain controllers), a central processing unit 3 (central processor), four remote antenna arrays 1 at the four corners of the vehicle, and a low-loss terahertz waveguide network 2 composed of low-loss flexible terahertz waveguides.

[0042] The input / output device 4 includes a domain controller located on the vehicle dashboard. The central processing unit includes a central processor embedded behind the steering wheel in the driver's cab. The remote antenna arrays 1 are respectively located at the two front corners and two rear corners of the vehicle. The central processing unit 3 and each remote antenna array 1 are connected by two separate low-loss flexible terahertz waveguides. The input / output device 4 and the central processing unit 3 are connected by ordinary data cables.

[0043] The central processing unit 3 includes a signal transceiver module, a signal conversion module, and a digital processing component. The signal transceiver module generates frequency-modulated continuous wave signals and receives echo signals, and includes a signal transmission channel, a signal reception channel, and a signal source. The signal conversion module converts the echo signals into digital signals and includes a mixer and an A / D converter. The digital processing component processes the digital signals and calculates and outputs the target distance, and includes an MCU.

[0044] The working principle of this embodiment is as follows: 1) System Startup and Command Input: The domain controller (such as the ADAS / autonomous driving domain controller) on the vehicle sends control commands to the central processing unit 3 via the command input module (such as the CAN FD interface). The commands include, but are not limited to, radar system wake-up, operating mode selection (such as long-range forward detection, short-range wide-angle surveillance, and cabin vital signs monitoring), and waveform parameter configuration.

[0045] 2) Centralized signal generation and transmission: The signal transceiver module in the central processing unit 3 generates a corresponding frequency-modulated continuous wave radio frequency signal according to the received instructions. After being amplified by an integrated power amplifier, the signal is transmitted through a dedicated low-loss terahertz wave transmitting waveguide to the remote transmitting antenna array 1 located at specific positions on the vehicle body (such as the front, rear, and four corners), and finally radiated into space by the antenna.

[0046] 3) Distributed signal reception and backhaul: The weak terahertz wave echo signal reflected back from the target is captured by the remote receiving antenna array 1 arranged in different directions. The signal is first preliminarily amplified by the low-noise amplifier integrated in the array to improve the signal-to-noise ratio. The amplified analog echo signal is then transmitted back to the central processing unit 3 with low loss and high fidelity through another independent low-loss terahertz wave receiving waveguide.

[0047] 4) Signal Processing and Information Extraction: The core processing flow of Central Processing Unit 3 is as follows: Frequency mixing: The returned analog echo signal and the transmitted signal sample are mixed in a mixer to generate an intermediate frequency signal containing target distance and speed information.

[0048] Digitalization: After being filtered, the intermediate frequency signal is converted into a digital signal by a high-speed analog-to-digital converter.

[0049] Algorithm processing: Digital processing components (including DSP, hardware accelerators, etc.) perform Fast Fourier Transform and Constant False Alarm Rate (CFR) processing on the digital signal to accurately calculate the target's distance and radial velocity. By comparing the phase differences of signals from multiple receiving channels, the target's azimuth and elevation angles are further calculated.

[0050] 5) Output and System Closed Loop: The digital processing component sends the generated structured target information list (including coordinates, speed, confidence level, etc.) or raw point cloud data to the vehicle domain controller in real time via a data cable. The domain controller makes fusion decisions based on this information to generate vehicle control commands (such as braking and steering). It can also issue new working commands to the central processing unit 3 according to changes in the environment, thus forming a dynamic and adaptive perception and control closed loop.

[0051] The fabrication method of the low-loss flexible terahertz waveguide is as follows: 1) Using a circular polycarbonate polymer base tube with an outer diameter of 5 mm, an inner diameter of 4 mm, and a length of 10 m, 300 mL of 1 mol / L sodium hydroxide solution was pumped into the polymer base tube at a flow rate of 30 mL / min using a peristaltic pump and cleaned for 10 min; then 300 mL of ethanol was pumped into the polymer base tube at a flow rate of 30 mL / min using a peristaltic pump and cleaned for 10 min; finally, 300 mL of deionized water was pumped into the polymer base tube at a flow rate of 30 mL / min using a peristaltic pump and cleaned for 10 min.

[0052] 2) Mix 30 mL of aminosilane coupling agent KH-550, 108 mL of ethanol, and 12 mL of deionized water, and stir for 30 min to ensure complete hydrolysis of the coupling agent. Then, use a peristaltic pump to pump the hydrolysate into the polymer base tube at a flow rate of 10 mL / min for pretreatment at room temperature for 15 min.

[0053] 3) The pretreated polymer-based tubes are then subjected to silver plating on the inner wall: First, a silver ammonia solution is prepared by dissolving 5.1g of silver nitrate and 1.22g of sodium hydroxide in 300mL of deionized water, and then adding 25% ammonia solution dropwise until the white precipitate is completely dissolved, yielding [Ag(NH3)2]. + Complexing solution. [Ag(NH3)2] + The complexing solution and 2.73g of glucose were dissolved in 300mL of deionized water as reducing agents. The two solutions were fed into the pretreated polymer-based tube at a flow rate of 120mL / min using a peristaltic pump with a Y-shaped tube. Silver plating was completed after 5 minutes, resulting in a low-loss flexible terahertz waveguide.

[0054] For this waveguide, infrared and X-ray detection are performed, such as Figure 4 and 5 As shown.

[0055] Figure 4 The FTIR detection results showed that at 1079 cm⁻¹ -1The absorption peaks that appeared were attributed to the Si-O-Si stretching vibrations, and their intensity increased with the degree of surface modification, indicating that the coupling agent reacted with the surface hydroxyl groups to form new Si-OC bonds, successfully achieving the grafting of the coupling agent onto the PC matrix surface; at 1504 cm⁻¹ -1 The absorption peaks that appear correspond to the bending and stretching vibrations of -NH2, indicating that amino functional groups have been introduced into the PC surface, and the peak intensity increases with the degree of modification; at 2963 cm⁻¹ -1 The absorption peak is attributed to the -CH stretching vibration, further proving that the coupling agent has an effective interaction with the PC surface.

[0056] Figure 5 XPS analysis results show: C 1s region: 284.8 eV corresponds to the CC / CH bond in the polycarbonate backbone; 286.5 eV corresponds to the CO-Si bond; 288.3 eV corresponds to the inherent carbonate group (-OC(=O)-O-) of polycarbonate; Si 2p region: 102.5 eV corresponds to the Si-OC bond, which corroborates the CO-Si signal in C 1s; 101.9 eV corresponds to the Si-C bond, indicating that the alkyl chain of the coupling agent remains intact during silver plating; Ag 3d high-resolution spectrum: the main peak (367.8 / 373.8 eV) corresponds to metallic silver (Ag 0 The secondary peak (368.9 / 374.8 eV) is positively shifted by about 1.0 eV relative to the metal peak, which is attributed to the coordination of Ag with nitrogen (Ag:N); the peak appearing at 400.9 eV in the N 1s region further confirms the coordination of Ag with -NH2.

[0057] Example 2 This embodiment provides a low-loss flexible terahertz wave hollow waveguide, which differs from Embodiment 1 in that the treatment time for step 2) amination modification is different. The modification time is adjusted to 20 minutes, as detailed below: Step 2): Mix 40 mL of aminosilane coupling agent KH-550, 144 mL of ethanol, and 16 mL of deionized water, and stir for 30 min to ensure complete hydrolysis of the coupling agent. Then, use a peristaltic pump to pump the hydrolysate into the polymer base tube at a flow rate of 10 mL / min for pretreatment at room temperature for 20 min.

[0058] Example 3 This embodiment provides a low-loss flexible terahertz wave hollow waveguide. The difference from Embodiment 1 lies in the time of the silver mirror reaction in step 3), with the modification time adjusted to 6 minutes, as detailed below: Step 3): The pretreated polymer base tube is then subjected to silver plating on its inner wall: First, a silver ammonia solution is prepared by dissolving 6.12g of silver nitrate and 1.46g of sodium hydroxide in 360mL of deionized water, and then adding 25% ammonia solution dropwise until the white precipitate is completely dissolved, yielding [Ag(NH3)2]. + Complexing solution. [Ag(NH3)2] + The complexing solution and 3.28 g of glucose were dissolved in 360 mL of deionized water as reducing agents. The two solutions were fed into the pretreated polymer-based tube at a flow rate of 120 mL / min using a peristaltic pump hose with a Y-shaped tube. Silver plating was completed after 6 minutes, resulting in a low-loss flexible terahertz waveguide.

[0059] Comparative Example 1 This comparative example provides a low-loss flexible terahertz wave hollow waveguide. The difference from Example 1 lies in the processing time of step 2) amination modification, which is adjusted to 5 minutes, as follows: Step 2): Mix 10 mL of aminosilane coupling agent KH-550, 36 mL of ethanol, and 4 mL of deionized water, and stir for 30 min to ensure complete hydrolysis of the coupling agent. Then, use a peristaltic pump to pump the hydrolysate into the polymer base tube at a flow rate of 10 mL / min for pretreatment at room temperature for 5 min.

[0060] Comparative Example 2 This comparative example provides a low-loss flexible terahertz wave hollow waveguide. The difference from Example 1 lies in the processing time of step 2) amination modification, which is adjusted to 10 minutes, as follows: Step 2): Mix 20 mL of aminosilane coupling agent KH-550, 72 mL of ethanol, and 8 mL of deionized water, and stir for 30 min to ensure complete hydrolysis of the coupling agent. Then, use a peristaltic pump to pump the hydrolysate into the polymer base tube at a flow rate of 10 mL / min for pretreatment at room temperature for 10 min.

[0061] Comparative Example 3 This comparative example provides a low-loss flexible terahertz wave hollow waveguide. The difference from Example 1 lies in the processing time of step 2) amination modification, which is adjusted to 25 minutes, as follows: Step 2): Mix 50 mL of aminosilane coupling agent KH-550, 180 mL of ethanol, and 20 mL of deionized water, and stir for 30 min to ensure complete hydrolysis of the coupling agent. Then, use a peristaltic pump to pump the hydrolysate into the polymer base tube at a flow rate of 10 mL / min for pretreatment at room temperature for 25 min.

[0062] Comparative Example 4 This embodiment provides a low-loss flexible terahertz wave hollow waveguide. The difference from Embodiment 1 is only in the processing time of the silver mirror reaction in step 3), which is adjusted to 3 minutes, as follows: Step 3): The pretreated polymer base tube is then subjected to silver plating on its inner wall: First, a silver ammonia solution is prepared by dissolving 3.06g of silver nitrate and 0.73g of sodium hydroxide in 180mL of deionized water, and then adding 25% ammonia solution dropwise until the white precipitate is completely dissolved, yielding [Ag(NH3)2]. + Complexing solution. [Ag(NH3)2] + The complexing solution and 1.64 g of glucose were dissolved in 180 mL of deionized water as reducing agents. The two solutions were fed into the pretreated polymer-based tube at a flow rate of 120 mL / min using a peristaltic pump hose with a Y-shaped tube. Silver plating was completed after 3 minutes.

[0063] Comparative Example 5 This comparative example uses a palladium-based activation optimization method to prepare an internally silver-plated polycarbonate waveguide, the specific method of which is as follows: 1) Using a 10m long, circular polycarbonate polymer base tube with an outer diameter of 5mm and an inner diameter of 4mm, 150mL of a 0.3mol / L stannous chloride solution was pumped into the polymer base tube at a flow rate of 30mL / min for 5min for sensitization. Then, 150mL of a 6×10⁻³mol / L palladium chloride solution was pumped into the polymer base tube at a flow rate of 30mL / min for palladium activation. The amounts of stannous chloride and palladium chloride added, as well as the modification time, were selected as optimal values.

[0064] 2) The polymer-based tube obtained in step 1) is subjected to silver plating on its inner wall: First, a silver ammonia solution is prepared by dissolving 5.1g of silver nitrate and 1.22g of sodium hydroxide in 300mL of deionized water, and then adding 25% ammonia solution dropwise until the white precipitate is completely dissolved, yielding [Ag(NH3)2]. + Complexing solution. [Ag(NH3)2] + The complexing solution and 2.73 g of glucose were dissolved in 300 mL of deionized water as reducing agents. The two solutions were fed into the pretreated polymer-based tube at a flow rate of 120 mL / min using a peristaltic pump hose with a Y-shaped tube. Silver plating was completed after 5 minutes to obtain the waveguide.

[0065] Experimental Example 1 In this experimental example, SEM and AFM were used to analyze the silver layer of the waveguide cross-sections of Examples 1-3 and Comparative Examples 1-5.

[0066] Figure 1 The images shown are SEM images of Example 1, Comparative Examples 1 and 3, and schematic diagrams of the nucleation mechanism of silver deposition; wherein, Figure 1 a and Figure 1 b shows the SEM image and nucleation mechanism diagram of Comparative Example 1. Figure 1 c and Figure 1 d is the SEM image and nucleation mode diagram of Example 1. Figure 1 e and Figure 1 f shows the SEM image and nucleation mechanism diagram of Comparative Example 3. It can be seen that the contact time of the coupling agent affects the nucleation mechanism of silver deposition. If the contact time is too short, the silver layer is distributed in an island-like pattern with high surface roughness; if the contact time is too long, the coupling agent molecules aggregate, leading to uneven silver deposition and increased roughness. Among these, the silver coating in Example 1 has the lowest surface roughness, while Comparative Examples 1 and 3 show obvious protrusions and high roughness.

[0067] Figure 2 A comparison of SEM images of the low-loss flexible terahertz waveguides in Examples 1, 3, and 4 is provided; among them, Figure 2 a is the SEM image of Example 1. Figure 2 b is the SEM image of Example 3. Figure 2 c is the SEM image of Comparative Example 4. Figure 2 Figure d shows the SEM image of Comparative Example 5. It can be seen that the thickness of the silver layer is highly sensitive to changes in the silver mirror reaction time. When the reaction time is 5 min and 6 min, the thickness of the silver layer remains relatively stable with little change. However, when the reaction time is reduced from 5 min to 3 min, the silver layer thickness decreases by 30%. An excessively thin silver layer leads to insufficient skin depth, increasing leakage loss; an excessively thick silver layer easily causes particle aggregation and increased surface roughness, which in turn increases scattering loss. Therefore, the preferred reaction time in this invention is 5-6 min.

[0068] Figure 3 A comparison of AFM images of low-loss flexible terahertz waveguides in Examples 1-2 and Comparative Examples 1-3; wherein, Figure 3 a is the AFM plot of Comparative Example 1. Figure 3 b is the AFM plot of Comparative Example 2. Figure 3 c is the AFM diagram of Example 1. Figure 3 d is the AFM diagram of Example 2. Figure 3 e is the AFM plot of Comparative Example 3. Figure 3 f shows the AFM plot of Comparative Example 5. It can be seen that when the amination modification time is 10-20 min, the surface roughness (Ra) of the waveguide remains around 10 nm, and the root mean square roughness (Rq) remains below 20 nm, indicating relatively small surface undulations. However, when the amination treatment time is greater than 20 min or less than 15 min, the surface roughness of the waveguide increases significantly, clearly rendering it impractical. The palladium-activated waveguide, on the other hand, has a Ra of 16.9 nm and an Rq of 23.1 nm, with a significantly higher surface roughness, which will lead to relatively higher transmission loss.

[0069] The experimental results have been verified multiple times and show good repeatability, proving that the method of the present invention can control the surface roughness of the silver layer by controlling the coupling agent treatment time and the thickness of the silver layer by controlling the silver mirror reaction time. When waveguides of different specifications need to be prepared, only adaptive adjustments are needed to quantitatively control the process.

[0070] Experiment Example 2 This experiment uses a vector network analyzer to measure the conventional transmission loss and the transmission loss under a bending radius of 20cm for waveguides in Examples 2-4 and Comparative Examples 1-5 using the truncation method. The results are as follows: Table 1. Typical Transmission Loss

[0071] Table 2 Transmission loss under a bending radius of 20cm

[0072] The simulated theoretical limit of transmission loss for a 220GHz waveguide is 0.68 dB / m. It can be seen that the transmission loss of the terahertz waveguide fabricated by the method of this invention is very close to the theoretical limit, maintaining low-loss transmission even with a bending radius of 20 cm. In contrast, the transmission loss of the traditional palladium-based activation method is 0.83 dB / m, and 1.00 dB / m with a bending radius of 20 cm. Compared to the terahertz waveguide of this invention, the transmission loss is improved by more than 10%.

[0073] Experimental Example 3 This experimental example uses a cross-cut adhesion test to determine the adhesion between the aminated and conventionally palladium-modified silver plating. The specific method is as follows: Two 20×20mm polycarbonate films were taken and activated under optimal conditions using aminosilane modification (amino modification time 15min) and palladium activation (stannous chloride sensitization 5min, palladium chloride activation 5min), respectively. Then, silvering was performed by silver mirror reaction for 5min. The specific operation is as described in Example 1 and Comparative Example 5.

[0074] Use a grid cutter to cut the silver-plated polycarbonate film into a 100-grid pattern. Then, cover the grid with tape and rub it back and forth with an eraser using a consistent motion to ensure full contact between the tape and the silver layer, without any air bubbles. Let it sit for 90 seconds, and then quickly and smoothly peel off the tape at a 90° angle within 1 second.

[0075] Test results are as follows Figure 6 As shown, where, Figure 6 a represents the adhesion effect of the palladium-activated polycarbonate film. Figure 6b represents the adhesion effect of the aminosilane-modified polycarbonate film. It can be seen that more silver layer meshes detach from the palladium-activated polycarbonate film, proving that aminosilane modification can make the silver layer adhere more tightly, have a denser structure, and higher bonding strength.

[0076] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A waveguide-integrated terahertz wave radar, characterized in that: Low-loss flexible terahertz waveguides are used as signal transmission channels; The method for fabricating the low-loss flexible terahertz waveguide Includes the following steps: S1: Activate the inner wall of the polymer matrix tube; S2: The inner wall is modified by amylation using an aminosilane coupling agent; S3: A silver plating layer is deposited on the inner wall by a silver mirror reaction.

2. The waveguide-integrated terahertz wave radar according to claim 1, characterized in that: The density of the silver plating layer is controlled by adjusting the amination modification time; the thickness of the silver plating layer is controlled by adjusting the silver mirror reaction time.

3. The waveguide-integrated terahertz wave radar according to claim 2, characterized in that: The amination modification time is 15-20 min; and / or the silver mirror reaction time is 5-6 min.

4. The waveguide-integrated terahertz wave radar according to any one of claims 1-3, characterized in that: The terahertz radar is installed on the vehicle and wired inside the vehicle's fuselage.

5. The waveguide-integrated terahertz wave radar according to claim 4, characterized in that: When the vehicle is a vehicle, the terahertz wave radar includes a central processing unit (3), a low-loss terahertz wave waveguide network (2), and several remote antenna arrays (1). The central processing unit (3) includes a signal transceiver module, a signal conversion module, and a digital processing component; The remote antenna array (1) includes a remote transmitting antenna array and a remote receiving antenna array; The central processing unit (3) is connected to each remote antenna array (1) via a low-loss flexible terahertz waveguide. The low-loss terahertz waveguide network (2) consists of several low-loss flexible terahertz waveguides embedded in the vehicle body.

6. The waveguide-integrated terahertz wave radar according to claim 5, characterized in that: The signal transceiver module is used to generate frequency-modulated continuous wave signals and receive echo signals, and includes at least a signal transmission channel, a signal reception channel, and a signal source.

7. The waveguide-integrated terahertz wave radar according to claim 6, characterized in that: The signal conversion module is used to convert the echo signal into a digital signal, and includes at least a mixer and an A / D converter.

8. The waveguide-integrated terahertz wave radar according to claim 7, characterized in that: The digital processing component is used to process the digital signal and calculate and output the target distance.

9. The waveguide-integrated terahertz wave radar according to claim 5, characterized in that: The terahertz wave radar also includes a command input / output device (4) for inputting commands and outputting distance results; the input / output device (4) transmits digital signals to the central processing unit (3) via a data line.

10. The waveguide-integrated terahertz wave radar according to claim 5, characterized in that: Each of the far-end antenna arrays (1) is connected to the central processing unit (3) via two independent low-loss flexible terahertz waveguides; one of which is connected to the signal transmission channel and the other is connected to the signal reception channel.

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