A method and system for testing the shielding effectiveness of radio frequency cables in an automotive environment

Abstract

The application discloses a kind of radio frequency cable shielding effectiveness test method and system under the environment of car, which comprises the following steps: determining the transmission attenuation reference value SE0 of the preset frequency radio frequency signal under the current test environment;Determine the first transmission power P ref of the radio frequency signal transmitted by the radio frequency cable to be tested placed on the first test table; Determine the second transmission power P dut of the radio frequency signal transmitted by the radio frequency cable to be tested placed on the second test table; Using the formula: SE=SE0-(P ref -P dut ), the shielding effectiveness SE of the radio frequency cable to be tested in the actual assembly environment on the car is calculated;Shielding effectiveness SE is used as the radio frequency cable shielding effectiveness under the environment of car. The shielding effectiveness of radio frequency cable in the environment of car can be quickly and accurately obtained by using the application, and cost is saved.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding testing, specifically relating to a method and system for testing the shielding effectiveness of radio frequency cables in an automotive environment. Background Technology

[0002] Shielding effectiveness refers to the ability of the shielding structure or materials of radio frequency (RF) cables to suppress external electromagnetic interference. In the complex electromagnetic environment inside and outside a car, when electromagnetic noise signals are present, if the shielding effectiveness of the RF cable is high, it can effectively suppress the propagation of external electromagnetic noise, prevent it from entering sensitive circuits, and improve the electromagnetic interference immunity of the car's electrical system.

[0003] Traditional methods for testing the shielding effectiveness of radio frequency (RF) cables can only evaluate the shielding effectiveness of RF cables under standard testing environments (e.g., the testing device and method for the shielding effectiveness of high-voltage cables for new energy vehicles disclosed in CN109375020A). In real-world automotive applications, it is necessary to combine the obtained cable parameters with the automotive metal structure for joint simulation evaluation using simulation tools. This process is time-consuming, and the simulation results may be inaccurate. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for testing the shielding effectiveness of radio frequency cables in an automotive environment, so as to quickly and accurately obtain the shielding effectiveness of radio frequency cables in an automotive environment.

[0005] The method for testing the shielding effectiveness of radio frequency cables in an automotive environment as described in this invention includes: Determine the transmission attenuation reference value SE0 of the radio frequency signal at a preset frequency under the current test environment; wherein, the preset frequency is the frequency that is actually used in automobiles and needs to be tested.

[0006] The first transmission power P of the radio frequency signal transmitted through the radio frequency cable under test placed on the first test platform is determined. ref The first test platform is an insulating board.

[0007] Determine the second transmission power P of the radio frequency signal transmitted through the radio frequency cable under test placed on the second test platform. dut The second test platform is a metal plate that simulates the actual assembly environment of radio frequency cables in a car.

[0008] Using the formula: SE = SE0 - (P) ref -P dut The shielding effectiveness SE of the radio frequency cable under test in the actual assembly environment of the automobile was calculated.

[0009] The shielding effectiveness SE is used as the shielding effectiveness of radio frequency cables in an automotive environment.

[0010] Preferably, the method for determining the transmission attenuation reference value SE0 of the radio frequency signal at a preset frequency under the current test environment includes: The RF transmitting antenna, RF receiving antenna, and balun (used to suppress common-mode interference from the antenna) are placed on the first test platform. The RF transmitting antenna is connected to the transmitting end of the RF signal transceiver processing device, and the RF receiving antenna is connected to the input end of the balun.

[0011] Connect the output of the balun to the receiver of the RF signal transceiver. The transmitter of the RF signal transceiver transmits a RF signal of a preset frequency through an RF transmitting antenna. The receiver receives the RF signal of the preset frequency through an RF receiving antenna, converts it via the balun, and transmits it to the receiver of the RF signal transceiver. The RF signal transceiver processes the received RF signal of the preset frequency to obtain the first calibration power P. mt .

[0012] The first calibration cable is placed on the first test platform. One end of the first calibration cable is connected to the output of the balun, and the other end is connected to the receiver of the RF signal transceiver. The transmitter of the RF signal transceiver transmits a RF signal of a preset frequency through the RF transmitting antenna. The RF receiving antenna receives the RF signal of the preset frequency, converts it through the balun, and transmits it to the receiver of the RF signal transceiver via the first calibration cable. The RF signal transceiver processes the received RF signal of the preset frequency to obtain the second calibration power P. cal The first calibration cable is a copper core wire formed by removing the shielding layer of the radio frequency cable.

[0013] Using the formula: SE0=P mt -P cal The transmission attenuation reference value SE0 is calculated.

[0014] Preferably, the first transmission power P of the radio frequency signal transmitted through the radio frequency cable under test placed on the first test platform is determined. ref The methods include: Place the RF transmitting antenna, RF receiving antenna, balun, and RF cable under test on the first test platform. Connect the RF transmitting antenna to the transmitting end of the RF signal transceiver processing device, connect the RF receiving antenna to the input end of the balun, connect one end of the RF cable under test to the output end of the balun, and connect the other end of the RF cable under test to the receiving end of the RF signal transceiver processing device.

[0015] The transmitting end of the RF signal transceiver processing device transmits an RF signal of a preset frequency through an RF transmitting antenna. The RF receiving antenna receives this RF signal, which is then converted by a balun and transmitted via the RF cable under test to the receiving end of the RF signal transceiver processing device. The RF signal transceiver processing device processes the received RF signal of the preset frequency to obtain the first transmission power P. ref .

[0016] Preferably, the second transmission power P of the radio frequency signal transmitted through the radio frequency cable under test placed on the second test platform is determined. dut The methods include: Place the RF transmitting antenna, RF receiving antenna, balun, and RF cable under test on the second test platform. Connect the RF transmitting antenna to the transmitting end of the RF signal transceiver processing device, connect the RF receiving antenna to the input end of the balun, connect one end of the RF cable under test to the output end of the balun, and connect the other end of the RF cable under test to the receiving end of the RF signal transceiver processing device.

[0017] The transmitting end of the RF signal transceiver processing device transmits an RF signal of a preset frequency through an RF transmitting antenna. The RF receiving antenna receives this RF signal, which is then converted by a balun and transmitted via the RF cable under test to the receiving end of the RF signal transceiver processing device. The RF signal transceiver processing device processes the received RF signal of the preset frequency to obtain the second transmission power P. dut .

[0018] The present invention discloses a radio frequency cable shielding effectiveness testing system in an automotive environment, which is used to implement the above-mentioned radio frequency cable shielding effectiveness testing method in an automotive environment. The testing system includes a radio frequency transmitting antenna, a radio frequency receiving antenna, a balun, a first test platform, a second test platform, a radio frequency cable under test, a first calibration cable, and a radio frequency signal transceiver processing device.

[0019] Preferably, the method for determining the transmission attenuation reference value SE0 of the radio frequency signal at a preset frequency under the current test environment includes: The first current clamp, the first impedance load, the second current clamp, and the second impedance load are placed on the first test platform. The first current clamp is connected to the transmitting end of the RF signal transceiver processing device, and the second current clamp is connected to the receiving end of the RF signal transceiver processing device. The first impedance load and the second impedance load are used to prevent signal reflection and absorb excess signal energy.

[0020] The second calibration cable is placed on the first test platform. One end of the second calibration cable is connected to the first impedance load, and the other end is connected to the second impedance load. A first current clamp holds one end of the second calibration cable, and a second current clamp holds the other end. The transmitting end of the RF signal transceiver processing device transmits a preset frequency RF signal through the first current clamp. This signal is coupled and transmitted to the receiving end of the RF signal transceiver processing device via the second calibration cable and the second current clamp. The RF signal transceiver processing device processes the received preset frequency RF signal to obtain the first calibration power P. mt The second calibration cable is a double-shielded cable with a shielding effectiveness greater than or equal to a preset effectiveness threshold, meaning that the second calibration cable has a very good shielding effect.

[0021] The first calibration cable is placed on the first test platform. One end of the first calibration cable is connected to the first impedance load, and the other end is connected to the second impedance load. A first current clamp holds one end of the first calibration cable, and a second current clamp holds the other end. The transmitting end of the RF signal transceiver processing device transmits a preset frequency RF signal through the first current clamp. The signal is coupled through the first calibration cable and the second current clamp and transmitted to the receiving end of the RF signal transceiver processing device. The RF signal transceiver processing device processes the received preset frequency RF signal to obtain the second calibration power P. cal The first calibration cable is a copper core wire formed by removing the shielding layer of the radio frequency cable.

[0022] Using the formula: SE0=P mt -P cal The transmission attenuation reference value SE0 is calculated.

[0023] Preferably, the first transmission power P of the radio frequency signal transmitted through the radio frequency cable under test placed on the first test platform is determined. ref The methods include: The first current clamp, the first impedance load, the second current clamp, the second impedance load, and the RF cable under test are placed on the first test platform. The first current clamp is connected to the transmitting end of the RF signal transceiver processing device, and the second current clamp is connected to the receiving end of the RF signal transceiver processing device. One end of the RF cable under test is connected to the first impedance load, and the other end of the RF cable under test is connected to the second impedance load. The first current clamp holds one end of the RF cable under test, and the second current clamp holds the other end of the RF cable under test.

[0024] The transmitting end of the RF signal transceiver processing device transmits an RF signal of a preset frequency through a first current clamp. This signal is coupled through the RF cable under test and a second current clamp, and then transmitted to the receiving end of the RF signal transceiver processing device. The RF signal transceiver processing device processes the received RF signal of the preset frequency to obtain the first transmission power P. ref .

[0025] Preferably, the second transmission power P of the radio frequency signal transmitted through the radio frequency cable under test placed on the second test platform is determined. dut The methods include: The first current clamp, the first impedance load, the second current clamp, the second impedance load, and the RF cable under test are placed on the second test platform. The first current clamp is connected to the transmitting end of the RF signal transceiver processing device, and the second current clamp is connected to the receiving end of the RF signal transceiver processing device. One end of the RF cable under test is connected to the first impedance load, and the other end of the RF cable under test is connected to the second impedance load. The first current clamp holds one end of the RF cable under test, and the second current clamp holds the other end of the RF cable under test.

[0026] The transmitting end of the RF signal transceiver processing device transmits an RF signal of a preset frequency through a first current clamp. This signal is coupled through the RF cable under test and a second current clamp, and then transmitted to the receiving end of the RF signal transceiver processing device. The RF signal transceiver processing device processes the received RF signal of the preset frequency to obtain the second transmission power P. dut .

[0027] Another radio frequency cable shielding effectiveness testing system in an automotive environment according to the present invention is used to implement the above-mentioned radio frequency cable shielding effectiveness testing method in an automotive environment. The testing system includes a first current clamp, a first impedance load, a second current clamp, a second impedance load, a first test platform, a second test platform, a radio frequency cable under test, a first calibration cable, a second calibration cable, and a radio frequency signal transceiver processing device.

[0028] Preferably, the radio frequency (RF) signal transceiver processing device includes an RF signal source, an RF power amplifier, a preamplifier, and a receiver processor. The output of the RF signal source is connected to the input of the RF power amplifier, and the output of the RF power amplifier serves as the transmitting end of the RF signal transceiver processing device. The input of the preamplifier serves as the receiving end of the RF signal transceiver processing device, and the output of the preamplifier is connected to the receiver processor. The RF signal source is an RF signal generator that provides the RF signal at the frequency required for testing (i.e., the frequency required for actual automotive applications and testing). The RF power amplifier amplifies the RF signal output from the RF signal source to excite the RF transmitting antenna or the first current clamp. The preamplifier amplifies the received RF signal and transmits it to the receiver processor. The receiver processor processes the received RF signal during the testing process to obtain the absolute power of the RF signal.

[0029] Preferably, the RF signal transceiver processing device includes a vector network analyzer, an RF power amplifier, and a preamplifier. The RF signal output terminal of the vector network analyzer is connected to the input terminal of the RF power amplifier. The output terminal of the RF power amplifier serves as the transmitting terminal of the RF signal transceiver processing device, and the input terminal of the preamplifier serves as the receiving terminal. The output terminal of the preamplifier is connected to the RF signal input terminal of the vector network analyzer. The vector network analyzer replaces both the RF signal source and the receiver processor, allowing for signal output and reception using a single device, which is more convenient and faster.

[0030] The present invention has the following effects: (1) No simulation evaluation is required. The shielding performance of radio frequency cables in the automotive environment can be directly calculated from the test data, realizing rapid and accurate testing of the shielding performance of radio frequency cables, while saving costs.

[0031] (2) By changing the placement of the radio frequency transmitting antenna and the radio frequency receiving antenna, radio frequency signals with different polarization directions can be injected, which is more flexible than the traditional method.

[0032] (3) By changing the type of radio frequency transmitting antenna and radio frequency receiving antenna, broadband or narrowband radio frequency signal injection can be achieved, enabling testing of radio frequency cables in any frequency band.

[0033] (4) The first current clamp and the second current clamp are used to realize the coupling transmission of radio frequency signals, and the shielding effectiveness of low frequency radio frequency cables can be evaluated. Attached Figure Description

[0034] Figure 1 This is a flowchart of a method for testing the shielding effectiveness of radio frequency cables in an automotive environment, as described in this embodiment of the invention.

[0035] Figure 2 This is one of the schematic diagrams of the test system structure built in Example 1 when determining the transmission attenuation reference value SE0.

[0036] Figure 3 This is the second schematic diagram of the test system structure built in Example 1 when determining the transmission attenuation reference value SE0.

[0037] Figure 4 To determine the first transmission power P in Example 1 ref A schematic diagram of the test system structure built at that time.

[0038] Figure 5 To determine the second transmission power P in Example 1 dut A schematic diagram of the test system structure built at that time.

[0039] Figure 6 This is a schematic diagram of the radio frequency signal transceiver processing device in Examples 2 and 4.

[0040] Figure 7 This is one of the schematic diagrams of the test system structure built in Example 3 when determining the transmission attenuation reference value SE0.

[0041] Figure 8 This is the second schematic diagram of the test system structure built in Example 3 when determining the transmission attenuation reference value SE0.

[0042] Figure 9 To determine the first transmission power P in Example 3 ref A schematic diagram of the test system structure built at that time.

[0043] Figure 10 To determine the second transmission power P in Example 3 dut A schematic diagram of the test system structure built at that time.

[0044] In the figure, 1-RF cable under test, 2-first calibration cable, 3-first test platform, 4-second test platform, 5-RF transmitting antenna, 6-RF receiving antenna, 7-balun, 8-first current clamp, 9-second current clamp, 10-first impedance load, 11-second impedance load, 12-second calibration cable, 13-RF power amplifier, 14-preamplifier, 15-receiver processor, 16-RF signal source, 17-vector network analyzer. Detailed Implementation

[0045] To gain a more detailed understanding of the features and technical content of the embodiments of the present invention, the implementation of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for reference and illustration only and are not intended to limit the embodiments of the present invention.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0047] It should also be noted that the terms "first" and "second" used in the embodiments of the present invention are only used to distinguish similar objects and do not represent a specific ordering of objects.

[0048] Example 1: As Figures 2 to 5 As shown, the radio frequency cable shielding effectiveness testing system in the automotive environment in this embodiment includes the radio frequency cable under test 1, the first calibration cable 2, the first test platform 3, the second test platform 4, the radio frequency transmitting antenna 5, the radio frequency receiving antenna 6, the balun 7, and the radio frequency signal transceiver processing device.

[0049] The first calibration cable 2 is a copper core wire formed by removing the shielding layer of the RF cable. The lengths of the RF cable under test 1 and the first calibration cable 2 are equal.

[0050] The first test platform 3 is an insulating board, and the second test platform 4 is a metal plate simulating the actual assembly environment of RF cables in an automobile. The first test platform 3 is used to test the RF cable under test 1 and the first calibration cable 2 in an environment away from metal. As an example, the first test platform 3 can be a wooden board.

[0051] The RF transmitting antenna 5, RF receiving antenna 6, and balun 7 are selected according to testing requirements. Broadband or narrowband antennas can be used to meet the needs of different testing frequencies. Additionally, RF signals with different polarization directions can be injected by changing the placement positions of the RF transmitting antenna 5 and RF receiving antenna 6. It should be noted that throughout the entire testing process in this embodiment, the placement positions of the RF transmitting antenna 5 and RF receiving antenna 6 on the first test platform 3 and on the second test platform 4 remain unchanged, thereby avoiding any impact on the test results due to changes in their positions.

[0052] The radio frequency (RF) signal transceiver processing device includes an RF signal source 16, an RF power amplifier 13, a preamplifier 14, and a receiver processor 15. The output of the RF signal source 16 is connected to the input of the RF power amplifier 13, and the output of the RF power amplifier 13 serves as the transmitting end of the RF signal transceiver processing device. The input of the preamplifier 14 serves as the receiving end of the RF signal transceiver processing device, and the output of the preamplifier 14 is connected to the receiver processor 15. It should be noted that the RF signal source 16 can generate an RF signal at a preset frequency, which is the frequency required for actual automotive applications and testing; the tester can adjust the RF signal source 16 to change the frequency of the RF signal. The receiver processor 15 can process the received RF signal to obtain the corresponding absolute power (unit: dBm, milliwatt-decibels), which the tester can directly read from the display screen of the receiver processor 15.

[0053] like Figure 1 As shown, the radio frequency cable shielding effectiveness testing method in this embodiment, using the aforementioned radio frequency cable shielding effectiveness testing system, specifically includes the following steps: Step 1: Determine the transmission attenuation reference value SE0 of the RF signal at the preset frequency under the current test environment. The specific determination method includes the following steps: S11. Place the RF transmitting antenna 5, RF receiving antenna 6, and balun 7 on the first test platform 3. Connect the RF transmitting antenna 5 to the output terminal of the RF power amplifier 13, and connect the RF receiving antenna 6 to the input terminal of the balun 7 (see...). Figure 2 , Figure 3 ).

[0054] S12. Connect the output of balun 7 to the input of preamplifier 14 (see...). Figure 2 The radio frequency signal source 16 generates and outputs a radio frequency signal at a preset frequency. After being amplified by the radio frequency power amplifier 13, the radio frequency signal at the preset frequency is transmitted by the radio frequency transmitting antenna 5. The radio frequency receiving antenna 6 receives the radio frequency signal at the preset frequency, converts it through the balun 7 (to suppress antenna common-mode interference), and transmits it to the preamplifier 14 for amplification. Then, the receiver processor 15 receives and processes the signal to obtain the first calibration power P. mt (Unit: dBm)

[0055] S13. Place the first calibration cable 2 on the first test platform 3, connect one end of the first calibration cable 2 to the output terminal of the balun 7, and connect the other end of the first calibration cable 2 to the input terminal of the preamplifier 14 (see...). Figure 3 The radio frequency signal source 16 generates and outputs a radio frequency signal at a preset frequency. After being amplified by the radio frequency power amplifier 13, the radio frequency transmitting antenna 5 transmits the radio frequency signal at the preset frequency. The radio frequency receiving antenna 6 receives the radio frequency signal at the preset frequency, converts it through the balun 7 (to suppress antenna common-mode interference), and transmits it to the preamplifier 14 for amplification via the first calibration cable 2. Then, the receiver processor 15 receives and processes the signal to obtain the second calibration power P. cal (Unit: dBm)

[0056] S14. Use the formula: SE0=P mt -P cal The transmission attenuation reference value SE0 (unit: dB) of the radio frequency signal at the preset frequency under the current test environment is calculated.

[0057] It should be noted that P mt This is the power transmitted directly through the various devices after passing through the RF signal source 16 in an environment far from metal (i.e., the first calibration power); it includes the gain of the RF power amplifier 13 and the preamplifier 14, as well as the losses of the RF transmitting antenna 5, the RF receiving antenna 6, and the balun 7; it should be noted that no cable is connected at this time, and the power data obtained represents the connection of a cable with infinite shielding effectiveness. P cal The transmission power (i.e., the second calibration power) is obtained after adding an unshielded calibration cable 2 in an environment far from metal. Therefore, P mt -P cal This represents the absolute power difference between a cable with infinite shielding effectiveness and an unshielded cable under the current test environment (away from metal). Under the same test conditions, this absolute power difference is a fixed value.

[0058] Step 2: Determine the first transmission power P of the radio frequency signal transmitted through the radio frequency cable 1 under test placed on the first test platform 3. ref Specific methods for determination include: First, place the RF transmitting antenna 5, RF receiving antenna 6, balun 7, and RF cable under test 1 on the first test platform 3. Connect the RF transmitting antenna 5 to the output of the RF power amplifier 13, connect the RF receiving antenna 6 to the input of the balun 7, connect one end of the RF cable under test 1 to the output of the balun 7, and connect the other end of the RF cable under test 1 to the input of the preamplifier 14 (see [link]). Figure 4 ).

[0059] Then, the RF signal source 16 generates and outputs an RF signal of a preset frequency. After being amplified by the RF power amplifier 13, the RF transmitting antenna 5 transmits the RF signal of the preset frequency. The RF receiving antenna 6 receives the RF signal of the preset frequency, converts it through the balun 7 (to suppress antenna common-mode interference), and transmits it through the RF cable under test 1 to the preamplifier 14 for amplification. Then, the receiver processor 15 receives and processes the signal to obtain the first transmission power P. ref It should be noted that the first transmission power P ref (Unit: dBm)

[0060] Step 3: Determine the second transmission power P of the radio frequency signal transmitted through the radio frequency cable 1 under test placed on the second test platform 4. dut Specific methods for determination include: First, place the RF transmitting antenna 5, RF receiving antenna 6, balun 7, and RF cable under test 1 on the second test platform 4. Connect the RF transmitting antenna 5 to the output of the RF power amplifier 13, connect the RF receiving antenna 6 to the input of the balun 7, connect one end of the RF cable under test 1 to the output of the balun 7, and connect the other end of the RF cable under test 1 to the input of the preamplifier 14 (see [link]). Figure 5 ).

[0061] Then, the RF signal source 16 generates and outputs an RF signal of a preset frequency. After being amplified by the RF power amplifier 13, the RF transmitting antenna 5 transmits the RF signal of the preset frequency. The RF receiving antenna 6 receives the RF signal of the preset frequency, converts it through the balun 7 (to suppress antenna common-mode interference), and transmits it through the RF cable under test 1 to the preamplifier 14 for amplification. Then, the receiver processor 15 receives and processes the signal to obtain the second transmission power P. dut (Unit: dBm)

[0062] Step 4: Use the formula: SE = SE0 - (P) ref -P dutThe shielding effectiveness SE (unit: dB) of the radio frequency cable 1 under test in the actual assembly environment of the car was calculated.

[0063] It should be noted that P ref -P dut This characterizes the signal transmission attenuation of the RF cable under test (1) due to the influence of the metal plate in the actual assembly environment of a simulated RF cable in an automobile. The better the shielding effectiveness of the RF cable under test, the smaller the corresponding difference. The attenuation reference value SE0 of the RF signal transmission at a preset frequency under the current test environment is subtracted from the degree of influence P of the RF signal power transmission performance caused by the metal plate. ref -P dut The value is used to characterize the shielding effectiveness SE, so that the shielding effectiveness of the RF cable under test 1 in the actual assembly environment of the car is more accurate.

[0064] Step 5: Use the shielding effectiveness SE as the shielding effectiveness of RF cables in an automotive environment.

[0065] Example 2: In this example, the method for testing the shielding effectiveness of RF cables in an automotive environment is the same as in Example 1. Most of the components of the test system are the same as in Example 1, except that the RF signal transceiver processing device uses a vector network analyzer 17 instead of the RF signal source 16 and the receiver processor 15 (see Example 2). Figure 6 The RF signal output terminal of the vector network analyzer 17 is connected to the input terminal of the RF power amplifier 13, and the output terminal of the preamplifier 14 is connected to the RF signal input terminal of the vector network analyzer 17. The vector network analyzer 17 can generate RF signals at a preset frequency and also process received RF signals to obtain the corresponding absolute power. The tester can adjust the frequency of the RF signal by adjusting the vector network analyzer 17, and the tester can directly read the absolute power of the received RF signal from the display screen of the vector network analyzer 17.

[0066] Example 3: As Figures 7 to 10 As shown, the radio frequency cable shielding effectiveness testing system in the automotive environment in this embodiment includes a radio frequency cable under test 1, a first calibration cable 2, a first test platform 3, a second test platform 4, a first current clamp 8, a first impedance load 10, a second current clamp 9, a second impedance load 11, a second calibration cable 12, and a radio frequency signal transceiver processing device.

[0067] The first calibration cable 2 is a copper core wire formed by removing the shielding layer of the RF cable. The second calibration cable 12 is a double-shielded cable with a shielding effectiveness greater than or equal to a preset effectiveness threshold. As an example, the preset effectiveness threshold is 90dB. The lengths of the RF cable under test 1, the first calibration cable 2, and the second calibration cable 12 are equal.

[0068] The first test platform 3 is an insulating board, and the second test platform 4 is a metal plate simulating the actual assembly environment of RF cables in an automobile. The first test platform 3 is used to test the RF cable under test 1 and the first calibration cable 2 in an environment away from metal. As an example, the first test platform 3 can be a wooden board.

[0069] As an example, the impedance values ​​of both the first impedance load 10 and the second impedance load 11 are 50Ω. The first impedance load 10 and the second impedance load 11 are used to prevent signal reflection and absorb excess signal energy.

[0070] The radio frequency (RF) signal transceiver processing device includes an RF signal source 16, an RF power amplifier 13, a preamplifier 14, and a receiver processor 15. The output of the RF signal source 16 is connected to the input of the RF power amplifier 13, and the output of the RF power amplifier 13 serves as the transmitting end of the RF signal transceiver processing device. The input of the preamplifier 14 serves as the receiving end of the RF signal transceiver processing device, and the output of the preamplifier 14 is connected to the receiver processor 15. It should be noted that the RF signal source 16 can generate an RF signal at a preset frequency, which is the frequency required for actual automotive applications and testing; the tester can adjust the RF signal source 16 to change the frequency of the RF signal. The receiver processor 15 can process the received RF signal to obtain the corresponding absolute power (unit: dBm, milliwatt-decibels), which the tester can directly read from the display screen of the receiver processor 15.

[0071] like Figure 1 As shown, the method for testing the shielding effectiveness of radio frequency cables in an automotive environment in this embodiment uses the aforementioned radio frequency cable shielding effectiveness testing system and specifically includes the following steps: Step 1: Determine the transmission attenuation reference value SE0 of the RF signal at the preset frequency under the current test environment. The specific determination method includes the following steps: S21. Place the first current clamp 8, the first impedance load 10, the second current clamp 9, and the second impedance load 11 on the first test platform 3. Connect the first current clamp 8 to the output terminal of the RF power amplifier 13, and connect the second current clamp 9 to the input terminal of the preamplifier 14 (see...). Figure 7 , Figure 8 ).

[0072] S22. Place the second calibration cable 12 on the first test platform 3, connect one end of the second calibration cable 12 to the first impedance load 10, connect the other end of the second calibration cable 12 to the second impedance load 11, clamp one end of the second calibration cable 12 with the first current clamp 8, and clamp the other end of the second calibration cable 12 with the second current clamp 9 (see...). Figure 7The radio frequency signal source 16 generates and outputs a radio frequency signal at a preset frequency. After being amplified by the radio frequency power amplifier 13, it is transmitted by the first current clamp 8, coupled through the second calibration cable 12 and the second current clamp 9, and then transmitted to the preamplifier 14 for amplification. Finally, it is received and processed by the receiver processor 15 to obtain the first calibration power P. mt (Unit: dBm)

[0073] S23. Place the first calibration cable 2 on the first test platform 3, connect one end of the first calibration cable 2 to the first impedance load 10, connect the other end of the first calibration cable 2 to the second impedance load 11, clamp one end of the first calibration cable 2 with the first current clamp 8, and clamp the other end of the first calibration cable 2 with the second current clamp 9 (see...). Figure 8 The radio frequency signal source 16 generates and outputs a radio frequency signal at a preset frequency. After being amplified by the radio frequency power amplifier 13, it is transmitted by the first current clamp 8, coupled through the first calibration cable 2 and the second current clamp 9, and then amplified by the preamplifier 14. Finally, it is received and processed by the receiver processor 15 to obtain the second calibration power P. cal (Unit: dBm)

[0074] S24. Use the formula: SE0=P mt -P cal The transmission attenuation reference value SE0 (unit: dB) of the radio frequency signal at the preset frequency under the current test environment is calculated.

[0075] Step 2: Determine the first transmission power P of the radio frequency signal transmitted through the radio frequency cable 1 under test placed on the first test platform 3. ref Specific methods for determination include: First, place the first current clamp 8, the first impedance load 10, the second current clamp 9, the second impedance load 11, and the RF cable under test 1 on the first test platform 3. The first current clamp 8 is connected to the output terminal of the RF power amplifier 13, and the second current clamp 9 is connected to the input terminal of the preamplifier 14. One end of the RF cable under test 1 is connected to the first impedance load 10, and the other end is connected to the second impedance load 11. The first current clamp 8 clamps one end of the RF cable under test 1, and the second current clamp 9 clamps the other end of the RF cable under test 1 (see...). Figure 9 ).

[0076] Then, the RF signal source 16 generates and outputs an RF signal at a preset frequency. After being amplified by the RF power amplifier 13, the signal is transmitted by the first current clamp 8, coupled through the RF cable under test 1 and the second current clamp 9, and then transmitted to the preamplifier 14 for amplification. Finally, the signal is received and processed by the receiver processor 15 to obtain the first transmission power P. ref (Unit: dBm)

[0077] Step 3: Determine the second transmission power P of the radio frequency signal transmitted through the radio frequency cable 1 under test placed on the second test platform 4. dut Specific methods for determining this include: First, place the first current clamp 8, the first impedance load 10, the second current clamp 9, the second impedance load 11, and the RF cable under test 1 on the second test platform 4. The first current clamp 8 is connected to the output terminal of the RF power amplifier 13, and the second current clamp 9 is connected to the input terminal of the preamplifier 14. One end of the RF cable under test 1 is connected to the first impedance load 10, and the other end is connected to the second impedance load 11. The first current clamp 8 clamps one end of the RF cable under test 1, and the second current clamp 9 clamps the other end of the RF cable under test 1 (see...). Figure 10 ).

[0078] Then, the RF signal source 16 generates and outputs an RF signal at a preset frequency. After being amplified by the RF power amplifier 13, the signal is transmitted by the first current clamp 8, coupled through the RF cable under test 1 and the second current clamp 9, and then transmitted to the preamplifier 14 for amplification. Finally, the signal is received and processed by the receiver processor 15 to obtain the second transmission power P. dut (Unit: dBm)

[0079] Step 4: Use the formula: SE = SE0 - (P) ref -P dut The shielding effectiveness SE (unit: dB) of the radio frequency cable 1 under test in the actual assembly environment of the car was calculated.

[0080] Step 5: Use the shielding effectiveness SE as the shielding effectiveness of RF cables in an automotive environment.

[0081] Example 4: The method for testing the shielding effectiveness of RF cables in an automotive environment in this example is the same as in Example 3. Most of the components of the test system are the same as in Example 3, except that the RF signal transceiver processing device uses a vector network analyzer 17 instead of the RF signal source 16 and the receiver processor 15 (see Example 3). Figure 6 The RF signal output terminal of the vector network analyzer 17 is connected to the input terminal of the RF power amplifier 13, and the output terminal of the preamplifier 14 is connected to the RF signal input terminal of the vector network analyzer 17. The vector network analyzer 17 can generate RF signals at a preset frequency and also process received RF signals to obtain the corresponding absolute power. The tester can adjust the frequency of the RF signal by adjusting the vector network analyzer 17, and the tester can directly read the absolute power of the received RF signal from the display screen of the vector network analyzer 17.

[0082] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for testing the shielding effectiveness of radio frequency cables in an automotive environment, characterized in that, include: Using the formula: SE0=P mt -P cal Calculate the transmission attenuation reference value SE0 of the radio frequency signal at a preset frequency under the current test environment; wherein, the preset frequency is the frequency actually used in automobiles and needs to be tested, P mt P is the transmission power of the radio frequency signal output from the radio frequency signal source in an environment far from metal, directly after passing through various devices. cal The transmission power is obtained by adding an unshielded first calibration cable in an environment far away from metal. The first calibration cable is a copper core wire formed by removing the shielding layer of the radio frequency cable. The first transmission power P of the radio frequency signal transmitted through the radio frequency cable (1) placed on the first test platform (3) is determined. ref The first test platform (3) is an insulating board. The second transmission power P of the radio frequency signal transmitted through the radio frequency cable (1) placed on the second test platform (4) is determined. dut The second test platform (4) is a metal plate that simulates the actual assembly environment of radio frequency cables in a car. Using the formula: SE = SE0 - (P) ref -P dut The shielding effectiveness SE of the radio frequency cable under test (1) in the actual assembly environment of the car was calculated. The shielding effectiveness SE is used as the shielding effectiveness of radio frequency cables in an automotive environment.

2. The method for testing the shielding effectiveness of radio frequency cables in an automotive environment according to claim 1, characterized in that, The transmission power P mt P cal The methods of obtaining it include: The radio frequency transmitting antenna (5), the radio frequency receiving antenna (6), and the balun (7) are placed on the first test platform (3). The radio frequency transmitting antenna (5) is connected to the transmitting end of the radio frequency signal transceiver processing device, and the radio frequency receiving antenna (6) is connected to the input end of the balun (7). Connect the output of the balun (7) to the receiving end of the radio frequency signal transceiver processing device; the transmitting end of the radio frequency signal transceiver processing device transmits a radio frequency signal of a preset frequency through the radio frequency transmitting antenna (5), and the radio frequency receiving antenna (6) receives the radio frequency signal of the preset frequency. The signal is converted by the balun (7) and transmitted to the receiving end of the radio frequency signal transceiver processing device, where the transmission power P is obtained. mt P mt It also indicates the first calibration power; Place the first calibration cable (2) on the first test platform (3), connect one end of the first calibration cable (2) to the output end of the balun (7), and connect the other end to the receiving end of the radio frequency signal transceiver processing device; the transmitting end of the radio frequency signal transceiver processing device transmits a radio frequency signal of a preset frequency through the radio frequency transmitting antenna (5), and the radio frequency receiving antenna (6) receives the radio frequency signal of the preset frequency, which is converted by the balun (7) and transmitted to the receiving end of the radio frequency signal transceiver processing device through the first calibration cable (2) to obtain the transmission power P. cal P cal It also indicates the second calibration power.

3. The method for testing the shielding effectiveness of radio frequency cables in an automotive environment according to claim 2, characterized in that, Determine the first transmission power P ref The methods include: The RF transmitting antenna (5), RF receiving antenna (6), balun (7), and RF cable under test (1) are placed on the first test platform (3). The RF transmitting antenna (5) is connected to the transmitting end of the RF signal transceiver processing device, the RF receiving antenna (6) is connected to the input end of the balun (7), and one end of the RF cable under test (1) is connected to the output end of the balun (7) and the other end is connected to the receiving end of the RF signal transceiver processing device. The transmitting end of the radio frequency signal transceiver processing device transmits a radio frequency signal of a preset frequency through the radio frequency transmitting antenna (5), and the radio frequency receiving antenna (6) receives the radio frequency signal of the preset frequency. After conversion by the balun (7), the signal is transmitted to the receiving end of the radio frequency signal transceiver processing device through the radio frequency cable under test (1) and processed to obtain the first transmission power P. ref .

4. The method for testing the shielding effectiveness of radio frequency cables in an automotive environment according to claim 2, characterized in that, Determine the second transmission power P dut The methods include: Place the RF transmitting antenna (5), RF receiving antenna (6), balun (7), and RF cable (1) under test on the second test platform (4). Connect the RF transmitting antenna (5) to the transmitting end of the RF signal transceiver processing device, connect the RF receiving antenna (6) to the input end of the balun (7), and connect one end of the RF cable (1) under test to the output end of the balun (7) and the other end to the receiving end of the RF signal transceiver processing device. The transmitting end of the radio frequency signal transceiver processing device transmits a radio frequency signal of a preset frequency through the radio frequency transmitting antenna (5), and the radio frequency receiving antenna (6) receives the radio frequency signal of the preset frequency. After conversion by the balun (7), the signal is transmitted to the receiving end of the radio frequency signal transceiver processing device through the radio frequency cable under test (1) and processed to obtain the second transmission power P. dut .

5. The method for testing the shielding effectiveness of radio frequency cables in an automotive environment according to claim 1, characterized in that, The transmission power P mt P cal The methods of obtaining it include: Place the first current clamp (8), the first impedance load (10), the second current clamp (9), and the second impedance load (11) on the first test platform (3). The first current clamp (8) is connected to the transmitting end of the radio frequency signal transceiver processing device, and the second current clamp (9) is connected to the receiving end of the radio frequency signal transceiver processing device. The second calibration cable (12) is placed on the first test platform (3). One end of the second calibration cable (12) is connected to the first impedance load (10), and the other end is connected to the second impedance load (11). The first current clamp (8) holds one end of the second calibration cable (12), and the second current clamp (9) holds the other end of the second calibration cable (12). The transmitting end of the radio frequency signal transceiver processing device transmits a radio frequency signal of a preset frequency through the first current clamp (8). The signal is coupled through the second calibration cable (12) and the second current clamp (9) and transmitted to the receiving end of the radio frequency signal transceiver processing device, where the transmission power P is obtained. mt P mt It also represents the first calibration power; wherein, the second calibration cable (12) is a double-shielded cable with shielding effectiveness greater than or equal to a preset effectiveness threshold; The first calibration cable (2) is placed on the first test platform (3). One end of the first calibration cable (2) is connected to the first impedance load (10), and the other end is connected to the second impedance load (11). The first current clamp (8) holds one end of the first calibration cable (2), and the second current clamp (9) holds the other end of the first calibration cable (2). The transmitting end of the radio frequency signal transceiver processing device transmits a radio frequency signal of a preset frequency through the first current clamp (8). The signal is coupled through the first calibration cable (2) and the second current clamp (9) and transmitted to the receiving end of the radio frequency signal transceiver processing device, where the transmission power P is obtained. cal P cal It also indicates the second calibration power.

6. The method for testing the shielding effectiveness of radio frequency cables in an automotive environment according to claim 5, characterized in that, Determine the first transmission power P ref The methods include: Place the first current clamp (8), the first impedance load (10), the second current clamp (9), the second impedance load (11), and the radio frequency cable (1) under test on the first test platform (3). The first current clamp (8) is connected to the transmitting end of the radio frequency signal transceiver processing device, and the second current clamp (9) is connected to the receiving end of the radio frequency signal transceiver processing device. One end of the radio frequency cable (1) under test is connected to the first impedance load (10), and the other end is connected to the second impedance load (11). The first current clamp (8) clamps one end of the radio frequency cable (1) under test, and the second current clamp (9) clamps the other end of the radio frequency cable (1) under test. The transmitting end of the radio frequency signal transceiver processing device transmits a radio frequency signal of a preset frequency through the first current clamp (8), which is coupled and transmitted to the receiving end of the radio frequency signal transceiver processing device via the radio frequency cable under test (1) and the second current clamp (9), and the first transmission power P is obtained after processing. ref .

7. The method for testing the shielding effectiveness of radio frequency cables in an automotive environment according to claim 5, characterized in that, Determine the second transmission power P dut The methods include: Place the first current clamp (8), the first impedance load (10), the second current clamp (9), the second impedance load (11), and the radio frequency cable (1) under test on the second test platform (4). The first current clamp (8) is connected to the transmitting end of the radio frequency signal transceiver processing device, and the second current clamp (9) is connected to the receiving end of the radio frequency signal transceiver processing device. One end of the radio frequency cable (1) under test is connected to the first impedance load (10), and the other end is connected to the second impedance load (11). The first current clamp (8) clamps one end of the radio frequency cable (1) under test, and the second current clamp (9) clamps the other end of the radio frequency cable (1) under test. The transmitting end of the radio frequency signal transceiver processing device transmits a radio frequency signal of a preset frequency through the first current clamp (8), which is coupled and transmitted to the receiving end of the radio frequency signal transceiver processing device via the radio frequency cable under test (1) and the second current clamp (9), and the second transmission power P is obtained after processing. dut .

8. The method for testing the shielding effectiveness of radio frequency cables in an automotive environment according to any one of claims 2 to 7, characterized in that: The radio frequency signal transceiver processing device includes a radio frequency signal source (16), a radio frequency power amplifier (13), a preamplifier (14), and a receiver processor (15); the output end of the radio frequency signal source (16) is connected to the input end of the radio frequency power amplifier (13), and the output end of the radio frequency power amplifier (13) serves as the transmitting end of the radio frequency signal transceiver processing device; the input end of the preamplifier (14) serves as the receiving end of the radio frequency signal transceiver processing device, and the output end of the preamplifier (14) is connected to the receiver processor (15).

9. The method for testing the shielding effectiveness of radio frequency cables in an automotive environment according to any one of claims 2 to 7, characterized in that: The radio frequency signal transceiver processing device includes a vector network analyzer (17), a radio frequency power amplifier (13), and a preamplifier (14). The radio frequency signal output terminal of the vector network analyzer (17) is connected to the input terminal of the radio frequency power amplifier (13). The output terminal of the radio frequency power amplifier (13) serves as the transmitting terminal of the radio frequency signal transceiver processing device, and the input terminal of the preamplifier (14) serves as the receiving terminal of the radio frequency signal transceiver processing device. The output terminal of the preamplifier (14) is connected to the radio frequency signal input terminal of the vector network analyzer (17).

10. A radio frequency cable shielding effectiveness testing system in an automotive environment, used to implement the testing method as described in any one of claims 1 to 4, the testing system comprising a radio frequency transmitting antenna (5), a radio frequency receiving antenna (6), a balun (7), a first test platform (3), a second test platform (4), a radio frequency cable under test (1), a first calibration cable (2), and a radio frequency signal transceiver processing device.

11. A radio frequency cable shielding effectiveness testing system in an automotive environment, used to implement the testing method as described in claim 1, 5, 6 or 7, the testing system comprising a first current clamp (8), a first impedance load (10), a second current clamp (9), a second impedance load (11), a first test platform (3), a second test platform (4), a radio frequency cable under test (1), a first calibration cable (2), a second calibration cable (12) and a radio frequency signal transceiver processing device.

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