Detachable electric field probe for measuring specific absorption rate of vehicle-mounted human body model and calibration method

Abstract

The invention discloses a detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model and a calibration method. The detachable electric field probe comprises a metal dipole, a polytetrafluoroethylene ring, a waterproof metal shell, a ferrite magnetic ring, an SMA connecting wire and a detachable rubber sleeve. In order to avoid tissue fluid leakage, except for the radiation unit of the metal dipole, other components are arranged in the waterproof metal shell. The inner conductor and the outer conductor of the SMA connecting line are respectively connected with the upper metal radiation unit and the lower metal radiation unit, the ferrite magnetic ring is sleeved on the SMA connecting line, and the problem of directional diagram distortion of the electric field probe under low frequency is obviously improved. The SMA connector is connected with the radio frequency receiver and the frequency spectrograph to obtain frequency spectrum information and the receiving power of the electric field probe, and the value can reflect the field intensity after calibration. The device can realize specific absorption rate measurement in a wide frequency band range, has the characteristics of small size, low manufacturing cost and convenience in use, and is suitable for specific absorption rate measurement in vehicle-mounted electromagnetic compatibility test, medical equipment evaluation and related scientific research fields.

Description

Technical Field

[0001] The invention relates to the technical field of specific absorption rate test and measurement, and in particular to a detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model and a calibration method. Background Art

[0002] With the continuous development of modern society, biomedical engineering and wireless communication technology are also evolving rapidly. Electronic products are becoming more and more popular and have become an indispensable part of people's daily lives. In recent years, the market share of electric vehicles has increased significantly, and the vehicles are equipped with a variety of electronic devices. These devices generally use radio frequency signals to transmit information, which may generate electromagnetic radiation and bring potential risks to human health.

[0003] In this context, in-vehicle specific absorption rate (SAR) measurements have become particularly important to ensure the safety and performance compliance of in-vehicle electronic equipment and protect the health of passengers. At present, electric field probes used to measure the SAR of electronic equipment on the market generally have problems such as high price, complex structure, lack of portability, and cannot be used in real human models, which limits the application scope of in-vehicle SAR testing. In addition, traditional probes are usually one-piece designs and difficult to disassemble, which increases the difficulty of replacement and calibration, increases measurement costs, prolongs test time, and reduces test efficiency.

[0004] Therefore, there is an urgent need for an electric field probe suitable for a vehicle-mounted human body model to effectively solve the above problems and provide a more efficient and convenient solution for vehicle-mounted SAR testing. Summary of the invention

[0005] The main purpose of the present invention is to provide a detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model and a calibration method, which can realize rapid disassembly and measurement on the vehicle-mounted human body model with low cost.

[0006] The present invention adopts the following technical solutions to solve the above technical problems: A detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model comprises: a copper metal dipole, a polytetrafluoroethylene ring, a waterproof aluminum shell, a ferrite magnetic ring, an SMA connecting line and a detachable rubber sleeve; the copper metal dipole comprises two symmetrically arranged copper metal columns and metal arms, the two copper metal columns are respectively placed in holes of the waterproof aluminum shell on both sides, and the copper metal arms are connected to the metal columns to form a symmetrical structure; the polytetrafluoroethylene ring is sleeved on the copper metal column in the copper metal dipole to block the copper metal column and the waterproof aluminum shell to prevent short circuit; the inner and outer conductors of the SMA connecting line are respectively welded to the bottom of the copper metal column in the two symmetrical copper metal dipole parts, and the ferrite magnetic ring is sleeved on the SMA connecting line to optimize the low-frequency directional diagram of the electric field probe.

[0007] Furthermore, the waterproof aluminum housing (3) comprises a front cover, a rear cover and upper and lower housing parts. The front and rear covers are fixed with screws, and the upper and lower housings adopt an upper and lower plug-in structure, which can prevent water from entering the housing and causing a short circuit.

[0008] Furthermore, the detachable rubber sleeve (6) comprises a silicone sleeve and a 3D printed bottle cap, wherein the silicone sleeve is fixed on the waterproof aluminum housing (3), and the 3D printed bottle cap is used to fix the entire electric field probe and the human body model and to play a detachable role.

[0009] Furthermore, the waterproof aluminum housing has a length, width and height of 60 mm, 13 mm and 10 mm respectively, the thickness of the front and rear covers is 1 mm, and the rear cover has a hole with a diameter of 3 mm for the SMA connecting line (5) to pass through.

[0010] On the other hand, the present invention also discloses a calibration method of a detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model, based on the above-mentioned detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model, characterized in that it comprises the following steps: First, the dielectric parameters of the tissue fluid were measured using a vector network analyzer to obtain the attenuation constant in the tissue fluid. ; Afterwards, the three-antenna method was used to calculate the near-field strength of the three antennas. The antennas were fixed in the tissue fluid and divided into three groups. The three antennas were tested facing each other. The two antennas were slowly moved away from each other using a guide rail. A set of data was recorded for each 1 mm distance. The three groups of antennas were recorded for each facing each other. , , , and simultaneously record the three antennas at this time , , ; Then use formulas (1), (2), and (3) to calculate the far-field strength of the antenna:

[0011]

[0012]

[0013]

[0014]

[0015] in, , , are the far-field gains of the three electric field probe antennas, , , Represent the reflection coefficients of No. 1, No. 2, and No. 3 electric field probes, respectively. , , Represent the transmission coefficient functions of probes 1 and 2, probes 1 and 3, and probes 2 and 3 as a function of distance, respectively. represents the attenuation constant in the liquid, represents the propagation constant in the liquid, represents the distance between the two antennas, is the wavelength in the liquid; By solving equations (1), (2) and (3) together, we can obtain the three power plant probes’ , , At the same time, due to the large loss in the liquid, it is measured in the near field so that the near-field gain can be regarded as a function of the distance r. Therefore, the far-field formula is extended to the near-field region. Formula (6) is the extended far-field gain formula, and formula (7) is the gain loss factor formula.

[0016]

[0017]

[0018] in, is the far-field gain of the E-field probe, is the distance between the antennas, is the gain reduction factor; and is a constant; obtained by least squares fitting , , ; get , , Then the electric field strength at a fixed distance is calculated using formula (8):

[0019] in, is the input power, is the reflection coefficient of the antenna, is the real part of the absolute value of the dielectric constant, is the distance between the two antennas, represents the attenuation constant in the liquid, is the far-field gain of the E-field probe, is the gain reduction factor; After calculating the field strength, the calibration coefficient is obtained by calculating the ratio of the previously measured pairwise received power to the calculated field strength to calibrate the electric field probe and obtain the electric field data at that location.

[0020] Furthermore, the constant and Obtained by least squares fitting.

[0021] Furthermore, the far-field gain Obtained by least squares fitting.

[0022] On the other hand, the present invention further discloses a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the above method.

[0023] On the other hand, the present invention further discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0024] It can be seen from the above technical scheme that the present invention provides a detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model, including a metal dipole, a polytetrafluoroethylene ring, a waterproof metal shell, a ferrite magnetic ring, an SMA connecting wire and a detachable rubber sleeve. In order to avoid leakage of tissue fluid, except for the radiation unit of the metal dipole, the remaining components are placed in the waterproof metal shell. The inner and outer conductors of the SMA connecting wire are respectively connected to the upper and lower metal radiation units, and the ferrite magnetic ring is sleeved on the SMA connecting wire, which significantly improves the directional pattern distortion problem of the electric field probe at low frequency. The SMA connector connects the radio frequency receiver and the spectrum analyzer to obtain the spectrum information and the receiving power of the electric field probe, which can reflect the magnitude of the field strength after calibration. The present invention can realize the specific absorption rate measurement within a wide frequency band, has the characteristics of small size, low cost and easy use, and is suitable for vehicle-mounted electromagnetic compatibility testing, medical equipment evaluation and specific absorption rate measurement in related scientific research fields.

[0025] Compared with other existing electric field probes for measuring specific absorption rate, the small detachable electric field probe for measuring specific absorption rate of a vehicle-mounted human body model provided by the present invention has the following significant advantages: (1) Low cost. Compared with other complete sets of specific absorption rate test probe systems that cost hundreds of thousands of yuan, the cost of the electric field probe in the present invention is controlled at a few hundred yuan, greatly reducing the cost.

[0026] (2) The scope of the specific absorption rate test is broadened. The traditional electric field probe cannot realize the specific absorption rate test of the vehicle-mounted human body model, but the present invention broadens the test scope.

[0027] (3) The quick disassembly design allows for quick disassembly from the human body model, enabling rapid testing of the specific absorption rate of the vehicle-mounted human body model.

[0028] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become easy to understand through the following description. Of course, it is not necessary to achieve all of the advantages described above simultaneously for any product implementing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the three-dimensional structure of the small detachable electric field probe provided by an embodiment of the present invention without the rubber cover; Figure 2 It is a schematic diagram of a top view of the structure of a small detachable electric field probe provided by an embodiment of the present invention with the rubber cover removed; Figure 3 This is a schematic diagram of the main structure of the small detachable electric field probe provided by an embodiment of the present invention without the rubber cover; Figure 4 It is a schematic diagram of the three-dimensional structure of a small detachable electric field probe provided in an embodiment of the present invention; Figure 5 1 is a schematic diagram of a top view of a small detachable electric field probe provided in an embodiment of the present invention; Figure 6 It is a schematic diagram of the main structure of a small detachable electric field probe provided by an embodiment of the present invention; Figure 7 It is a schematic diagram of the main structure of a small detachable electric field probe provided by an embodiment of the present invention; Figure 8 This is a simulation diagram of the total efficiency curve of a small detachable electric field probe provided by an embodiment of the present invention; Fig. 9 This is a comparison diagram of the plane directional diagrams of the small detachable electric field probe provided by an embodiment of the present invention at 600 MHz without and with a magnetic ring; Fig.10This is a comparison diagram of the plane directional diagrams of the small detachable electric field probe provided by an embodiment of the present invention at 800 MHz without and with a magnetic ring; Fig.11 This is a comparison diagram of the plane directional diagrams of the small detachable electric field probe provided by an embodiment of the present invention at 1000 MHz without and with a magnetic ring; Fig.12 This is a real picture of the measurement of the dielectric constant of the liquid environment used by the small detachable electric field probe provided in an embodiment of the present invention; Fig.13 This is a real shot of the calibration of the small detachable electric field probe provided in an embodiment of the present invention.

[0030] Fig.14 It is a received power diagram at various position distances of the small detachable electric field probe provided by an embodiment of the present invention.

[0031] Fig.15 It is a diagram of the electric field magnitude at various positions of the small detachable electric field probe provided by an embodiment of the present invention.

[0032] Fig.16 It is a calibration coefficient diagram of a small detachable electric field probe provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] like Figure 1-6 As shown, a small detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model according to an embodiment of the present invention comprises: a copper metal dipole 1, a polytetrafluoroethylene ring 2, a waterproof aluminum shell 3, a ferrite magnetic ring 4, an SMA connecting wire 5 and a detachable rubber sleeve 6; the copper metal dipole 1 comprises two symmetrically arranged copper metal columns and metal arms, the two copper metal columns are respectively placed in holes of the waterproof aluminum shell 3 on both sides, and the copper metal arms are connected to the metal columns to form a symmetrical structure; the polytetrafluoroethylene ring 2 is sleeved on the copper metal column in the copper metal dipole 2 to block the copper metal column and the waterproof aluminum shell 3 to prevent a short circuit; the inner and outer conductors of the SMA connecting wire 5 are respectively welded to the bottom of the copper metal columns in the two symmetrical copper metal dipole 1 parts, and the ferrite magnetic ring 3 is sleeved on the connecting wire to optimize the low-frequency radiation pattern of the electric field probe.

[0035] Specifically, in this embodiment, the copper metal dipole 1 is divided into two parts, the upper part is a trapezoid made of copper plus two arm-shaped metals, the conductivity of copper is 56.0MS / m, the lengths of the long and short sides of the trapezoid are 24mm and 6mm respectively, the length and width of the arms on both sides are 9.6mm and 2.4mm respectively, and the metal thickness is 2mm. The lower part is a copper metal cylinder with a diameter of 6mm. There are two identical structures to form a pair of dipoles. The polytetrafluoroethylene ring 2 is sleeved on the copper metal cylinder below the copper metal dipole 1 to play an insulating role, preventing the internal antenna part from directly contacting the metal shell. The inner diameter and outer diameter of the polytetrafluoroethylene ring 2 are 6mm and 8.4mm respectively. The inner and outer conductors of the SMA connecting wire 5 are respectively welded to the bottom of the copper metal columns in the two symmetrical copper metal dipoles 1 to receive radio frequency signals. The ferrite ring 3 is sleeved on the RG316 radio frequency connecting wire with a diameter of 2.5 mm. The radio frequency connecting wire is mainly used for the transmission of radio frequency signals of 0-6 GHz, which meets all the frequencies included in the design. At the same time, the ferrite ring 3 further optimizes the low-frequency radiation pattern of the electric field probe.

[0036] The waterproof aluminum housing 3 consists of four parts, namely a front cover, a rear cover and upper and lower housing parts. The front and rear covers are fixed with screws, and the upper and lower housings adopt an upper and lower inserted embedded structure, which can effectively prevent water from entering the housing and causing a short circuit. The entire housing is made of aluminum. There is a circular hole with a diameter of 3mm at the rear cover, which is mainly used to pass the RG316 radio frequency connecting line. A circular hole of 8.4mm is opened at the front end of the upper and lower housings respectively, which is used to fix the lower circular ring part of the copper metal dipole 1.

[0037] like Figure 4-7 As shown, in the present embodiment, a small detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model is provided. In order to realize the detachability of the electric field probe on the human body model, a detachable rubber sleeve 6 is additionally added to the electric field probe body. The structure is composed of two parts, namely a rubber sleeve and a 3D printed bottle cap. The function of the rubber sleeve is to prevent the leakage of tissue fluid inside the human body model. Moreover, due to its arbitrarily retractable and deformable characteristics, the electric field probe can be controlled to retract in the human body model to measure the specific absorption rate value at each depth. The function of the 3D printed bottle cap is to help fix the entire electric field probe at the position of the model that needs to be measured. The specific effect diagram of the fixed connection of the bottle cap is shown in FIG. Figure 7 shown.

[0038] Since the electric field probe receives data in the form of received power, it is necessary to convert the received power into electric field strength. The present invention adopts the following algorithm to convert power into field strength, that is, to perform calibration: First, the dielectric parameters of the tissue fluid were measured using a vector network analyzer to obtain the attenuation constant in the tissue fluid. Specific test scenarios such as Fig.12 shown.

[0039] Afterwards, the three-antenna method is used to calculate the near-field strength of the three antennas. The specific test diagram is as follows: Fig.13 As shown, the antennas are fixed in the tissue fluid. The three antennas are divided into three groups and tested facing each other. The two antennas are slowly moved away from each other using the guide rail. A set of data is recorded for each 1mm distance. The data of the three groups of antennas facing each other is recorded. , , , and simultaneously record the three antennas at this time , , Then use formulas (1), (2) and (3) to calculate the far-field strength of the antenna:

[0040]

[0041]

[0042]

[0043]

[0044] in, , , are the far-field gains of the three electric field probe antennas, , , Represent the reflection coefficients of No. 1, No. 2, and No. 3 electric field probes, respectively. , , Represent the transmission coefficient functions of probes 1 and 2, probes 1 and 3, and probes 2 and 3 as a function of distance, respectively. represents the attenuation constant in the liquid, represents the propagation constant in the liquid, represents the distance between the two antennas, is the wavelength in the liquid.

[0045] By solving (1), (2), and (3) together, we can obtain the three power plant probes , , At the same time, due to the large loss in the liquid, it should be measured in the near field so that the near-field gain can be regarded as a function of the distance r. Therefore, the far-field formula is extended to the near-field region. Formula (6) is the extended far-field gain formula, and formula (7) is the gain loss factor formula.

[0046]

[0047]

[0048] in, is the far-field gain of the E-field probe, is the distance between the antennas. The constant and It can be obtained by least squares fitting. like Fig.14 shown.

[0049] get , , The electric field strength at a fixed distance can then be calculated using formula (8):

[0050] in, is the input power, is the reflection coefficient of the antenna, is the real part of the absolute value of the dielectric constant, is the distance between the two antennas, represents the attenuation constant in the liquid, is the far-field gain of the E-field probe, is the gain reduction factor.

[0051] After calculating the field strength, based on the previously measured received power between the two nodes, Fig.15 As shown, by calculating the ratio with the calculated field strength, the calibration coefficient can be obtained to calibrate the electric field probe and obtain the electric field data at the position.

[0052] The specific steps are summarized as follows: (1) The dielectric parameter properties of tissue fluid are measured by vector network analyzer and coaxial probe method, and the attenuation constant is calculated. , the propagation constant .

[0053] (2) Using the three-antenna method and the Friis formula, the three antennas are grouped in pairs and tested head-on to obtain , , , and obtain three sets of data in distance units.

[0054] (3) When When the distance is large enough, measure the three antennas separately. , , .

[0055] (4) Fit the measured data to the formula (6), and then fit it using the least squares method. , , .

[0056] (5) After obtaining the fitting results, the electric field at each position during calibration is obtained using the electric field formula.

[0057] (6) Compare the electric field at each position with the received power obtained in step (2) to obtain a calibration curve. The final calibration curve is as follows: Fig.16 shown.

[0058] The application effect of the present invention is described in detail below in conjunction with simulation.

[0059] Figure 8 The total efficiency curve simulation diagram of the present invention is given. It can be seen that the electric field probe of the present invention achieves full screen coverage of 30MHz-6GHz, and the efficiency can reach up to 70% in the covered frequency band.

[0060] Figure 9-11 The radiation pattern comparison of the present invention in two different situations is given, which is a comparison of adding a magnetic ring and removing the magnetic ring. Fig. 9 This is a directional diagram comparison diagram of 600MHz. The left side is with a magnetic ring and the right side is without a magnetic ring. Fig.10 This is a comparison of the directional diagrams at 800MHz. The left side shows the pattern with a magnetic ring and the right side shows the pattern without a magnetic ring. Fig.11 The left side is the directional diagram comparison diagram of 1000MHz with the magnetic ring and the right side is the directional diagram without the magnetic ring. It can be seen that the directivity of the entire directional diagram is much improved after adding the magnetic ring compared to without the magnetic ring, which shows that our improvement is very effective.

[0061] In summary, the electric field probe of the present invention realizes a small detachable design for measuring the specific absorption rate of a vehicle-mounted human body model. On the basis of combining the actual test and measurement environment, a set of usable specific absorption rate test and measurement schemes is redesigned, and the cost is low, and it can be widely used in the specific absorption rate test of the human body model. At the same time, the entire electric field probe is very small (240mm*240mm), and the specific absorption rate of the human body can be measured within 30MHz-6GHz. In addition, due to the addition of a magnetic ring to improve the directionality of the electric field probe, its directionality is also greatly improved at low frequencies. The present invention can realize the specific absorption rate measurement within a wide frequency band, has the characteristics of small size, low cost and convenient use, and is suitable for electromagnetic compatibility testing, medical equipment evaluation and specific absorption rate measurement in related scientific research fields.

[0062] On the other hand, the present invention further discloses a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the above method.

[0063] On the other hand, the present invention further discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0064] In another embodiment provided by the present application, a computer program product including instructions is also provided, which, when executed on a computer, enables the computer to execute any of the detachable electric field probes for measuring the specific absorption rate of a vehicle-mounted human body model in the above embodiments.

[0065] It is understandable that the system provided by the embodiment of the present invention corresponds to the method provided by the embodiment of the present invention, and the explanation, examples and beneficial effects of the relevant contents can refer to the corresponding parts in the above method.

[0066] The embodiment of the present application also provides an electronic device, including a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus. Memory, used to store computer programs; The processor is used to implement the above-mentioned detachable electric field probe for measuring the specific absorption rate of the vehicle-mounted human body model when executing the program stored in the memory.

[0067] The communication bus mentioned in the above electronic device may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus may be divided into an address bus, a data bus, a control bus, etc.

[0068] The communication interface is used for communication between the above electronic device and other devices.

[0069] The memory may include a random access memory (RAM) or a non-volatile memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0070] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components.

[0071] It should also be noted that electronic devices also include terminal devices, which can also be called terminals, user equipment (UE), mobile stations (MS), mobile terminals (MT), etc. Terminal devices can be mobile phones, smart TVs, wearable devices, tablet computers (Pad), computers with wireless transceiver functions, virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, etc. The embodiments of the present application do not limit the specific technology and specific device form adopted by the terminal devices.

[0072] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive Solid State Disk (SSD)), etc.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0074] In addition, it should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0075] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, in the embodiments of the present invention, "multiple" refers to more than two. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model, characterized in that: include: Copper metal dipole (1), polytetrafluoroethylene ring (2), waterproof aluminum housing (3), ferrite magnetic ring (4), SMA connecting wire (5) and detachable rubber sleeve (6); The copper metal dipole (1) comprises two symmetrically arranged copper metal columns and metal arms, the two copper metal columns are respectively placed in holes of the waterproof aluminum housing (3) on both sides, and the copper metal arms are connected to the metal columns; The polytetrafluoroethylene ring (2) is sleeved on the copper metal column in the copper metal dipole (1) to block the copper metal column and the waterproof aluminum housing (3) to prevent short circuit; The inner and outer conductors of the SMA connecting wire (5) are respectively welded to the bottoms of the copper metal columns in the two symmetrical copper metal dipole (1) parts, and the ferrite magnetic ring (4) is sleeved on the SMA connecting wire (5) to optimize the low-frequency directivity diagram of the electric field probe.

2. The detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model according to claim 1, characterized in that: The waterproof aluminum housing (3) comprises a front cover, a rear cover and upper and lower housing parts. The front and rear covers are fixed by screws, and the upper and lower housing parts adopt an upper and lower plug-in structure, which can prevent water from entering the housing and causing a short circuit.

3. The detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model according to claim 1, characterized in that: The detachable rubber sleeve (6) comprises a silicone sleeve and a 3D printed bottle cap, wherein the silicone sleeve is fixed on the waterproof aluminum housing (3), and the 3D printed bottle cap is used to fix the entire electric field probe and the human body model and to play a detachable role.

4. The detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model according to claim 1, characterized in that: The waterproof aluminum housing has a length, width and height of 60 mm, 13 mm and 10 mm respectively, and the thickness of the front and rear covers is 1 mm. The rear cover is provided with a hole with a diameter of 3 mm for the SMA connecting wire (5) to pass through.

5. A calibration method for a detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model, based on the detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model according to any one of claims 1 to 4, characterized in that: The following steps are included: First, the dielectric parameters of the tissue fluid were measured using a vector network analyzer to obtain the attenuation constant in the tissue fluid. ; Afterwards, the three-antenna method was used to calculate the near-field strength of the three antennas. The antennas were fixed in the tissue fluid and divided into three groups. The three antennas were tested facing each other. The two antennas were slowly moved away from each other using a guide rail. A set of data was recorded for each 1 mm distance. The three groups of antennas were recorded for each facing each other. , , , and simultaneously record the three antennas at this time , , ; Then use formulas (1), (2), and (3) to calculate the far-field strength of the antenna: in, , , are the far-field gains of the three electric field probe antennas, , , Represent the reflection coefficients of No. 1, No. 2, and No. 3 electric field probes, respectively. , , Represent the transmission coefficient functions of probes 1 and 2, probes 1 and 3, and probes 2 and 3 as a function of distance, respectively. represents the attenuation constant in the liquid, represents the propagation constant in the liquid, represents the distance between the two antennas, is the wavelength in the liquid; By solving equations (1), (2) and (3) together, we can obtain the three power plant probes’ , , ; At the same time, due to the large loss in the liquid, it is measured in the near field so that the near field gain can be regarded as a function of the distance r. Therefore, the far field formula is extended to the near field region. Formula (6) is the extended far field gain formula, and formula (7) is the gain loss factor formula. in, is the far-field gain of the E-field probe, is the distance between the antennas, is the gain reduction factor; and is a constant; obtained by least squares fitting , and ; get , , Then the electric field strength at a fixed distance is calculated using formula (8): in, is the input power, is the reflection coefficient of the antenna, is the real part of the absolute value of the dielectric constant, is the distance between the two antennas, represents the attenuation constant in the liquid, is the far-field gain of the E-field probe, is the gain reduction factor; After calculating the field strength, the calibration coefficient is obtained by calculating the ratio of the previously measured pairwise received power to the calculated field strength to calibrate the electric field probe and obtain the electric field data at that location.

6. The calibration method of a detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model according to claim 5, characterized in that: constant and Obtained by least squares fitting.

7. The calibration method of a detachable electric field probe for measuring the specific absorption rate of a vehicle-mounted human body model according to claim 5, characterized in that: Far Field Gain Obtained by least squares fitting.

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