Vehicle-mounted antenna and impedance matching method

Abstract

The invention provides a vehicle-mounted antenna and an impedance matching method, and relates to the technical field of wireless communication, and the vehicle-mounted antenna comprises a circuit board, and an antenna module and an impedance matching module which are printed on the circuit board; the antenna module and the impedance matching module are determined based on the following steps: determining the width of the signal wiring of the antenna module based on the height from the signal wiring on the circuit board to the reference ground plane and the thickness of the signal wiring; determining the signal wiring length of the antenna module based on the dielectric constant of the circuit board and the signal wavelength of the antenna module; performing electromagnetic field simulation on the antenna module based on the signal wiring width and the signal wiring length, and determining the input impedance of the antenna module; and determining device parameters of each device in the impedance matching module based on the input impedance of the antenna module. According to the antenna and the method provided by the invention, the miniaturization of the vehicle-mounted antenna is realized, and the impedance matching accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a vehicle-mounted antenna and an impedance matching method. Background Art

[0002] With the rapid development of wireless communication technology, antennas have become one of the key components of automotive wireless electronic communication equipment, and their design faces unprecedented opportunities and challenges.

[0003] The trend of miniaturization of automotive wireless electronic communication equipment forces antennas to have low profiles and low-cost features. In addition, more and more functions are integrated into automotive electronic devices, and other electronic devices occupy the space occupied by antennas, resulting in a smaller and smaller net space for antennas, and the size of antennas needs to be continuously reduced. Since a series of performances such as antenna transmission and reception frequency, return loss, gain, etc. are closely related to the size of the antenna, it is difficult to miniaturize the antenna.

[0004] In addition, impedance matching is related to whether the antenna can work properly. In the matching process, multiple device parameters must be adjusted at the same time, and these parameters may affect each other, making impedance matching difficult and time-consuming.

[0005] Therefore, how to miniaturize the design of vehicle-mounted antennas and improve the accuracy of impedance matching has become a technical problem that needs to be urgently solved in the industry. Summary of the invention

[0006] The invention provides a vehicle-mounted antenna and an impedance matching method, which are used to solve the technical problems of how to miniaturize the design of the vehicle-mounted antenna and improve the accuracy of impedance matching.

[0007] The present invention provides a vehicle-mounted antenna, comprising a circuit board, and an antenna module and an impedance matching module printed on the circuit board; The antenna module and the impedance matching module are determined based on the following steps: Determining a width of a signal trace of the antenna module based on a height of the signal trace on the circuit board from a reference ground plane and a thickness of the signal trace; Determining a signal trace length of the antenna module based on a dielectric constant of the circuit board and a signal wavelength of the antenna module; Based on the signal wiring width and the signal wiring length, performing electromagnetic field simulation on the antenna module to determine the input impedance of the antenna module; Based on the input impedance of the antenna module, the device parameters of each device in the impedance matching module are determined.

[0008] In some embodiments, the routing shape of the antenna module is serpentine.

[0009] In some embodiments, the circuit board is a double-layer circuit board; the intermediate medium of the circuit board is glass fiber reinforced epoxy resin.

[0010] The present invention provides an impedance matching method applied to the vehicle-mounted antenna, including: Obtaining the input impedance of the antenna module in the vehicle-mounted antenna and determining the coordinate point of the input impedance in the Smith chart; Moving the coordinate point of the input impedance to the center position in the Smith chart and determining the moving direction and moving distance of the coordinate point of the input impedance; Based on the moving direction and moving distance of the coordinate point of the input impedance, determining the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure.

[0011] In some embodiments, the determining the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure based on the moving direction and moving distance of the coordinate point of the input impedance includes: When the moving direction is moving along the constant resistance circle in the clockwise direction, adding a series inductor in the impedance matching module; When the moving direction is moving along the constant conductance circle in the counterclockwise direction, adding a parallel inductor in the impedance matching module; When the moving direction is moving along the constant resistance circle in the counterclockwise direction, adding a series capacitor in the impedance matching module; When the moving direction is moving along the constant conductance circle in the clockwise direction, adding a parallel capacitor in the impedance matching module.

[0012] In some embodiments, after determining the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure, the method further includes: Determining a plurality of parameter scaling factors; Performing a multiplication operation on the device parameters of each device and each parameter scaling factor to determine a plurality of candidate device parameters of each device; Based on the antenna scattering parameter curves of each device when obtaining each candidate device parameter, determining the optimal parameter scaling factor corresponding to each device; Based on the optimal parameter scaling factor corresponding to each device, determining the optimized device parameter corresponding to each device.

[0013] In some embodiments, the determining the optimal parameter scaling factor corresponding to each device based on the antenna scattering parameter curves of each device when obtaining each candidate device parameter includes: Analyze the antenna scattering parameter curves of each device when obtaining the parameters of each candidate device, and determine the correlation coefficient between the change of the parameter scaling factor and the change of the antenna scattering parameters; When the correlation coefficient is greater than a preset correlation threshold, determine the parameter scaling factor corresponding to the minimum value of the antenna scattering parameters as the optimal parameter scaling factor.

[0014] In some embodiments, after determining the correlation coefficient between the change of the parameter scaling factor and the change of the antenna scattering parameters, the method further includes: When the correlation coefficient is less than or equal to the preset correlation threshold, determine the frequency at which the minimum value of the antenna scattering parameters corresponding to each parameter scaling factor is located; When the frequency at which the minimum value of the antenna scattering parameters corresponding to any parameter scaling factor is the resonant frequency of the antenna module, determine the any parameter scaling factor as the optimal parameter scaling factor.

[0015] The present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the impedance matching method described above is implemented.

[0016] The present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the impedance matching method described above is implemented.

[0017] The vehicle-mounted antenna and impedance matching method provided by the present invention include a circuit board, and an antenna module and an impedance matching module printed on the circuit board. The wiring shape of the antenna module is serpentine, effectively reducing the space of the antenna on the circuit board; the circuit board is a double-layer circuit board, and the intermediate medium of the circuit board is glass fiber-reinforced epoxy resin, realizing the miniaturization of the vehicle-mounted antenna. Perform electromagnetic field simulation according to the signal wiring width and signal wiring length of the antenna, and perform iterative optimization according to the obtained input impedance to determine the device parameters of each device in the impedance matching module, effectively simplifying the PCB antenna design process and improving the accuracy of impedance matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.

[0019] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a schematic structural diagram of a vehicle-mounted antenna provided by the present invention.

[0021] Figure 2 It is a schematic diagram of an antenna module provided by the present invention.

[0022] Figure 3 It is a schematic flow diagram of a vehicle-mounted antenna design method provided by the present invention.

[0023] Figure 4 It is a schematic diagram of the characteristic impedance and the input impedance provided by the present invention.

[0024] Figure 5 It is a schematic diagram of parameters provided by the present invention.

[0025] Figure 6 It is a schematic circuit diagram of an impedance matching module provided by the present invention.

[0026] Figure 7 It is a schematic flow diagram of an impedance matching method provided by the present invention.

[0027] Figure 8 It is a schematic diagram of a Smith chart provided by the present invention.

[0028] Figure 9 It is one of the schematic diagrams of the scattering parameter curves after device parameter sweeping provided by the present invention.

[0029] Figure 10 It is another schematic diagram of the scattering parameter curves after device parameter sweeping provided by the present invention.

[0030] Figure 11 It is a schematic diagram of the device parameter optimization process provided by the present invention.

[0031] Figure 12 It is a schematic diagram of the initial input impedance provided by the present invention.

[0032] Figure 13 It is a schematic diagram of the initial scattering parameter curve provided by the present invention.

[0033] Figure 14 It is a schematic diagram of the antenna input impedance after impedance matching provided by the present invention.

[0034] Figure 15It is a schematic diagram of the scattering parameter curve after impedance matching provided by the present invention.

[0035] Figure 16 It is a schematic diagram of the antenna input impedance after optimizing the device parameters provided by the present invention.

[0036] Figure 17 It is a schematic diagram of the scattering parameter curve after optimizing the device parameters provided by the present invention.

[0037] Figure 18 It is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed implementation manners

[0038] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] It should be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units or modules does not necessarily have to be limited to those steps or units or modules clearly listed, but may include other steps or units or modules not clearly listed or inherent to these processes, methods, products or devices.

[0040] The communication module antenna with a transmitting and receiving frequency of 433 MHz (megahertz) is widely used in fields such as remote control devices, smart homes, in-vehicle electronics, and the Internet of Things. Since a series of performances of the antenna, such as the transmitting and receiving frequencies, return loss, and gain, are closely related to the antenna size, currently, the 433 MHz communication module antenna is mainly an external spring antenna and a rod antenna, which occupy a relatively large volume.

[0041] To solve the deficiencies of the related art, Figure 1 It is a schematic diagram of the structure of the vehicle-mounted antenna provided by the present invention. As Figure 1 shown, the vehicle-mounted antenna 100 includes a circuit board 110, and an antenna module 120 and an impedance matching module 130 printed on the circuit board 110.

[0042] Specifically, the vehicle-mounted antenna provided by the embodiments of the present invention can be used in scenarios such as vehicle communication, navigation, and entertainment. Structurally, the vehicle-mounted antenna mainly includes a printed circuit board (PCB), an antenna module, and an impedance matching module.

[0043] The circuit board can adopt a double-layer structure. The outer layer of the circuit board consists of two layers of conductive copper foils, with an insulating layer sandwiched in the middle. The intermediate medium is glass fiber-reinforced epoxy resin, such as FR-4. FR stands for Flame Retardant, and 4 represents the material number. Glass fiber-reinforced epoxy resin is a composite material. The glass fiber provides mechanical strength and stability, and the epoxy resin acts as an adhesive to bond the glass fiber cloth together and endows the material with electrical insulation properties.

[0044] The antenna module can be directly drawn on the outer layer of the double-layer circuit board, usually the top layer. This design method enables the antenna to be directly integrated on the circuit board, saving space and having a lower cost. The circuit corresponding to the impedance matching module can also be set on the double-layer circuit board to achieve a compact and efficient antenna integration.

[0045] The routing shape of the antenna module on the circuit board is serpentine. The serpentine antenna realizes a miniaturized antenna structure by bending and folding the wire, transforming the straight-line structure of the traditional antenna into a compact shape, thus significantly reducing the occupied area of the antenna and can be manufactured using PCB technology, with a lower cost compared to traditional antennas.

[0046] Figure 2 is a schematic diagram of the antenna module provided by the present invention. As Figure 2 shown, the size of the serpentine antenna provided by the embodiments of the present invention can be 34mm * 15mm (length * width, unit: millimeter), and the maximum gain is -1.69 dBi (the radiation efficiency in a specific direction is 1.69 dB lower than that of an ideal omnidirectional antenna). dB is the decibel.

[0047] Figure 3 is a schematic flowchart of the vehicle-mounted antenna design method provided by the present invention. As Figure 3 shown, the antenna module and the impedance matching module are determined based on the following steps: Step 310: Determine the signal trace width of the antenna module based on the height of the signal trace on the circuit board from the reference ground plane and the thickness of the signal trace. Step 320: Determine the signal trace length of the antenna module based on the dielectric constant of the circuit board and the signal wavelength of the antenna module. Step 330: Perform electromagnetic field simulation on the antenna module based on the signal trace width and the signal trace length to determine the input impedance of the antenna module. Step 340: Determine the device parameters of each device in the impedance matching module based on the input impedance of the antenna module.

[0048] Specifically, the purpose of impedance matching is to ensure impedance matching between the antenna and the transmission line (such as a feeder line), so as to maximize power transmission and reduce reflection loss. The vehicle-mounted antenna design method is mainly used to design and implement the antenna module and the impedance matching module, and the main steps are as follows: First, determine the signal trace width of the antenna module according to the height of the signal trace on the circuit board from the reference ground plane and the thickness of the signal trace.

[0049] A signal trace is a conductive path on a printed circuit board (PCB) for transmitting electrical signals. Figure 4 It is a schematic diagram of the characteristic impedance and input impedance provided by the present invention. As Figure 4 shown, in transmission line theory, when the terminal of a transmission line with a characteristic impedance of is connected to a load with an impedance of , the input impedance of this transmission line can be expressed as: where is the wavelength of the signal propagating on the transmission line, which is related to the material and size of the transmission line; is the length of the transmission line; represents the imaginary unit.

[0050] For a PCB printed antenna, the equivalent terminal load impedance between the transmitting antenna and the receiving antenna cannot be directly determined, so the optimal line width of the PCB antenna cannot be directly calculated. Generally, the characteristic impedance of the PCB trace is equal to 50 ohms as the initial line width, and the formula for the initial line width is as follows: Figure 5 It is a schematic diagram of the parameters provided by the present invention. As Figure 5 shown, is the dielectric constant of the substrate material, is the height of the signal trace from the reference ground plane (conductive plane, used to provide a stable reference potential and return path for the signal), is the thickness of the signal trace. The initial line width calculated from the above formula can be used as the signal trace width of the antenna module.

[0051] Secondly, determine the signal trace length of the antenna module according to the dielectric constant of the circuit board and the signal wavelength of the antenna module.

[0052] According to the signal frequency , the speed of light The wavelength in space can be calculated as follows: When an electromagnetic wave propagates in a dielectric medium and the corresponding dielectric constant is , its propagation speed is: For a PCB antenna, the dielectric constant of the PCB material and the surrounding air must be considered. Its effective dielectric constant is: where is the thickness of the PCB material, is the width of the PCB antenna. Then the formula for calculating the PCB length of the required quarter-wavelength monopole antenna is as follows: The PCB length calculated from the above formula can be used as the signal trace length of the antenna module.

[0053] Again, according to the signal trace width and signal trace length, perform electromagnetic field simulation on the antenna module to determine the input impedance of the antenna module.

[0054] The antenna module can be simulated through electromagnetic field simulation software or S-parameter (scattering parameters, key indicators for describing signal transmission and reflection characteristics in RF and microwave systems) test devices such as network analyzers to obtain the S-parameters and input impedance of the antenna module.

[0055] The ultimate design goal of the antenna module is to make the antenna input impedance close to 50 ohms and make the frequency point where the minimum value of the antenna S-parameter is located, that is, the resonant frequency of the antenna, at 433 MHz.

[0056] Finally, according to the input impedance of the antenna module, determine the device parameters of each device in the impedance matching module.

[0057] Figure 6 is the circuit schematic diagram of the impedance matching module provided by the present invention. As Figure 6 shown, the impedance matching module is composed of devices combined in series or parallel. The devices include inductors and capacitors. Devices 1 to device can be increased or decreased according to actual needs.

[0058] The input impedance can be used to perform 50-ohm impedance matching through the Smith chart. The Smith Chart is a graphical tool used in RF engineering and microwave engineering, mainly for analyzing and designing impedance matching networks. Locate the current input impedance on the Smith chart, and then move this point to the center position through the series and parallel combinations of inductors and capacitors to complete the 50-ohm impedance matching.

[0059] If the input impedance and S-parameters of the PCB antenna after impedance matching still cannot meet the design goals, the device parameters of the circuit components after impedance matching can be further optimized.

[0060] The vehicle-mounted antenna provided by the embodiment of the present invention includes a circuit board, as well as an antenna module and an impedance matching module printed on the circuit board. The wiring shape of the antenna module is serpentine, effectively reducing the space of the antenna on the circuit board; the circuit board is a double-layer circuit board, and the intermediate medium of the circuit board is glass fiber-reinforced epoxy resin, realizing the miniaturization of the vehicle-mounted antenna. Electromagnetic field simulation is carried out according to the signal wiring width and signal wiring length of the antenna, and iterative optimization is carried out according to the obtained input impedance to determine the device parameters of each device in the impedance matching module, effectively simplifying the PCB antenna design process and improving the accuracy of impedance matching.

[0061] Figure 7 is a schematic flow chart of the impedance matching method provided by the present invention. As Figure 7 shown, this method is applied to the design process of the vehicle-mounted antenna in the above embodiment, and includes step 710, step 720, and step 730.

[0062] Step 710: Obtain the input impedance of the antenna module in the vehicle-mounted antenna, and determine the coordinate point of the input impedance on the Smith chart.

[0063] Step 720: Move the coordinate point of the input impedance to the center position on the Smith chart, and determine the moving direction and moving distance of the coordinate point of the input impedance.

[0064] Step 730: Based on the moving direction and moving distance of the coordinate point of the input impedance, determine the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure.

[0065] Specifically, the execution subject of the impedance matching method provided by the embodiment of the present invention is an impedance matching device. This device can be implemented by software, such as a software program for executing the impedance matching method; it can also be implemented by hardware, such as a computer for executing the impedance matching method.

[0066] During the design process of a vehicle-mounted antenna, the input impedance of the antenna module can be obtained. Determine the coordinate point of this input impedance in the Smith chart. The Smith chart maps complex impedance (or admittance) onto a polar coordinate plot, helping to visually understand and solve impedance matching problems.

[0067] Move the coordinate point of the input impedance to the center position in the Smith chart, and record the moving direction and moving distance of the coordinate point of the input impedance. Then, based on the moving direction and moving distance of the coordinate point of the input impedance, determine the circuit structure of the impedance matching module in the vehicle-mounted antenna, that is, determine the number of devices (inductors and capacitors) to be included in the impedance matching module and the connection method (series and parallel), and then determine the device parameters of these devices, that is, determine the specific inductance value and capacitance value.

[0068] The impedance matching method provided by the embodiments of the present invention obtains the input impedance of the antenna module in the vehicle-mounted antenna, and determines the coordinate point of the input impedance in the Smith chart; moves the coordinate point of the input impedance to the center position in the Smith chart, and determines the moving direction and moving distance of the coordinate point of the input impedance; based on the moving direction and moving distance of the coordinate point of the input impedance, determines the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure; performs electromagnetic field simulation according to the signal trace width and signal trace length of the antenna, and performs iterative optimization according to the obtained input impedance to determine the device parameters of each device in the impedance matching module, effectively simplifying the PCB antenna design process and improving the accuracy of impedance matching.

[0069] In some embodiments, based on the moving direction and moving distance of the coordinate point of the input impedance, determining the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure includes: When the moving direction is moving along the constant-resistance circle in the clockwise direction, add a series inductor in the impedance matching module; When the moving direction is moving along the constant-conductance circle in the counterclockwise direction, add a parallel inductor in the impedance matching module; When the moving direction is moving along the constant-resistance circle in the counterclockwise direction, add a series capacitor in the impedance matching module; When the moving direction is moving along the constant-conductance circle in the clockwise direction, add a parallel capacitor in the impedance matching module.

[0070] Specifically, Figure 8 is a schematic diagram of the Smith chart provided by the present invention. As Figure 8 shown, when the moving direction of the coordinate point of the input impedance is moving along the constant-resistance circle in the clockwise direction, a series inductor needs to be added in the impedance matching module, and the inductance value of this inductor can be determined according to the moving distance It is determined and expressed by the formula as: When the moving direction of the coordinate point of the input impedance is to move along the constant conductance circle in the counterclockwise direction, a parallel inductor needs to be added to the impedance matching module, and the inductance value of this inductor can be determined according to the moving distance It is determined and expressed by the formula as: When the moving direction of the coordinate point of the input impedance is to move along the constant resistance circle in the counterclockwise direction, a series capacitor needs to be added to the impedance matching module, and the capacitance value of this capacitor can be determined according to the moving distance It is determined and expressed by the formula as: When the moving direction of the coordinate point of the input impedance is to move along the constant conductance circle in the clockwise direction, a parallel capacitor needs to be added to the impedance matching module, and the capacitance value of this capacitor can be determined according to the moving distance It is determined and expressed by the formula as: The impedance matching method provided by the embodiment of the present invention determines the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure according to the moving direction and moving distance of the coordinate point of the input impedance, improving the accuracy of impedance matching.

[0071] In some embodiments, after determining the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure, the method further includes: Determine a plurality of parameter scaling factors; Perform a multiplication operation on the device parameters of each device and each parameter scaling factor to determine a plurality of candidate device parameters of each device; Based on the antenna scattering parameter curves of each device when obtaining each candidate device parameter, determine the optimal parameter scaling factor corresponding to each device; Based on the optimal parameter scaling factor corresponding to each device, determine the optimized device parameter corresponding to each device.

[0072] Specifically, parameter sweeping refers to the process of observing how the system performance indicators (such as the S-parameters of the antenna) change with the change of one or more parameter values by changing the values of one or more parameters during the simulation or experiment process. In antenna design, parameter sweeping is usually used to optimize the antenna performance, such as adjusting the size, material properties or other design parameters of the antenna. The method of optimizing the circuit device parameters by scanning the circuit device parameters after impedance matching is described below.

[0073] The parameter scaling factor can be determined for optimizing the selection of device parameters for each device. The parameter scaling factor can be expressed as , Multiple values can be selected between [0, 2], such as 0.4, 0.7, 1, 1.3, and 1.7.

[0074] Multiply the device parameters of each device by each parameter scaling factor to determine multiple candidate device parameters for each device. For example, the first device is a capacitor, and the capacitance value of this capacitor is C. After multiplying by each parameter scaling factor, multiple candidate device parameters 0.4C, 0.7C, C, 1.3C, and 1.7C are obtained.

[0075] By sweeping the parameters of the selected values, the antenna S-parameter (scattering parameter) curves of each device under the condition of obtaining each candidate device parameter are obtained respectively. These antenna S-parameter curves can be analyzed to determine the optimal parameter scaling factor corresponding to each device. The optimal parameter scaling factor is the one that makes the S-parameter minimum or the frequency point where the minimum value of the S-parameter is located (a specific frequency value, representing a single frequency position).

[0076] According to the optimal parameter scaling factor corresponding to each device, adjust the device parameters of each device to obtain the optimized device parameters corresponding to each device. For example, for the first device being a capacitor and the optimal parameter scaling factor being 0.7, the optimized device parameter is 0.7C.

[0077] The impedance matching method provided by the embodiments of the present invention scans the circuit device parameters after impedance matching, optimizes the circuit device parameters, and improves the accuracy of impedance matching.

[0078] In some embodiments, based on the antenna scattering parameter curves of each device under the condition of obtaining each candidate device parameter, determining the optimal parameter scaling factor corresponding to each device includes: Analyze the antenna scattering parameter curves of each device under the condition of obtaining each candidate device parameter to determine the correlation coefficient between the change of the parameter scaling factor and the change of the antenna scattering parameter; When the correlation coefficient is greater than a preset correlation threshold, determine the parameter scaling factor corresponding to the minimum value of the antenna scattering parameter as the optimal parameter scaling factor.

[0079] Specifically, according to the analysis of the antenna scattering parameter curves of each device under the condition of obtaining each candidate device parameter, determine the correlation coefficient between the change of the parameter scaling factor and the change of the antenna scattering parameter. The correlation coefficient is used to describe the influence degree of the parameter scaling factor on the antenna scattering parameter.

[0080] If the correlation coefficient is greater than a preset correlation threshold (the preset correlation threshold can be set according to the actual situation), it indicates that the influence degree of the parameter scaling factor on the antenna scattering parameter is relatively large. That is, the change of the parameter scaling factor mainly affects the magnitude of the scattering parameter. Then, the parameter scaling factor corresponding to the minimum value of the antenna scattering parameter can be determined as the optimal parameter scaling factor.

[0081] Figure 9 is one of the schematic diagrams of the scattering parameter curve after the device parameter sweeping provided by the present invention. As Figure 9 shown, the first device performs parameter sweeping on the value. It can be found that the parameter scaling factor mainly affects the magnitude of the scattering parameter, and the value corresponding to the minimum value of the antenna scattering parameter is 0.7.

[0082] The impedance matching method provided by the embodiments of the present invention determines the optimal parameter scaling factor according to the influence degree of the parameter scaling factor on the antenna scattering parameter, improving the accuracy of impedance matching.

[0083] In some embodiments, after determining the correlation coefficient between the change of the parameter scaling factor and the change of the antenna scattering parameter, the method further includes: In the case where the correlation coefficient is less than or equal to the preset correlation threshold, determine the frequency at which the minimum value of the antenna scattering parameter corresponding to each parameter scaling factor is located; In the case where the frequency at which the minimum value of the antenna scattering parameter corresponding to any parameter scaling factor is located is the resonance frequency of the antenna module, determine any parameter scaling factor as the optimal parameter scaling factor.

[0084] Specifically, if the correlation coefficient is less than or equal to the preset correlation threshold, it indicates that the influence degree of the parameter scaling factor on the antenna scattering parameter is relatively small. At this time, the frequency at which the minimum value of the antenna scattering parameter corresponding to each parameter scaling factor is located can be determined.

[0085] If the frequency at which the minimum value of the antenna scattering parameter corresponding to any parameter scaling factor is located is the resonance frequency of the antenna module (such as 433 MHz), then this parameter scaling factor can be determined as the optimal parameter scaling factor.

[0086] Figure 10 is the second schematic diagram of the scattering parameter curve after the device parameter sweeping provided by the present invention. As Figure 10 shown, the second device performs parameter sweeping on the value. It can be found that the parameter scaling factor mainly affects the frequency at which the minimum value of the antenna scattering parameter is located, and when the value is 1.4, the frequency at which the minimum value of the antenna scattering parameter is located is 433 MHz (resonance frequency).

[0087] The impedance matching method provided by the embodiment of the present invention determines the optimal parameter scaling factor according to the influence degree of the parameter scaling factor on the frequency at which the minimum value of the antenna scattering parameter is located, improving the accuracy of impedance matching.

[0088] Figure 11 is a schematic diagram of the device parameter optimization process provided by the present invention, as Figure 11 shown. First, the circuit device values after impedance matching are respectively multiplied by p, and multiple values of p are selected between 0 and 2. By sweeping the selected p values, the antenna S-parameter curves when different circuit device values are multiplied by different p values are obtained respectively. Analyze the antenna S-parameter curves when each device value is multiplied by different p values. If the change in the p value mainly affects the magnitude of the S parameter, then the p value that makes the S parameter minimum is taken as the final value; otherwise, according to its influence trend on the frequency point where the minimum value of the S parameter is located, and comprehensively considering the combined influence of the p parameters of other devices, the frequency point where the minimum value of the S parameter is located is moved to the required frequency point.

[0089] Technically in each embodiment, the antenna design method includes the following steps.

[0090] Step 1, determine the initial line width and initial length of the PCB antenna according to the PCB board material, perform electromagnetic field simulation, and obtain the input impedance and scattering parameters of the current PCB antenna.

[0091] Figure 12 is a schematic diagram of the initial input impedance provided by the present invention, Figure 13 is a schematic diagram of the initial scattering parameter curve provided by the present invention. The initial input impedance is as Figure 12 shown, and the corresponding scattering parameter curve is as Figure 13 shown.

[0092] Step 2, use the input impedance to perform 50-ohm impedance matching through the Smith chart.

[0093] Figure 14 is a schematic diagram of the antenna input impedance after impedance matching provided by the present invention, Figure 15 is a schematic diagram of the scattering parameter curve after impedance matching provided by the present invention. The input impedance after impedance matching is as Figure 14 shown, and the corresponding scattering parameter curve is as Figure 15 shown.

[0094] Step 3, optimize the circuit device parameters by scanning the circuit device parameters after impedance matching.

[0095] Figure 16 is a schematic diagram of the antenna input impedance after device parameter optimization provided by the present invention, Figure 17 is a schematic diagram of the scattering parameter curve after device parameter optimization provided by the present invention. The input impedance after device parameter optimization is as Figure 16As shown, the corresponding scattering parameter curves are as Figure 17 shown.

[0096] Figure 18 FIG. Figure 18 is a schematic structural diagram of an electronic device provided by the present invention. As Figure 18 shown, the electronic device may include: a processor 1810, a communications interface 1820, a memory 1830, and a communications bus 1840. Among them, the processor 1810, the communications interface 1820, and the memory 1830 complete mutual communication through the communications bus 1840. The processor 1810 may call logic commands in the memory 1830 to execute the methods described in the foregoing embodiments. For example: Obtain the input impedance of the antenna module in the vehicle-mounted antenna, and determine the coordinate point of the input impedance in the Smith chart; move the coordinate point of the input impedance to the center position in the Smith chart, and determine the moving direction and moving distance of the coordinate point of the input impedance; based on the moving direction and moving distance of the coordinate point of the input impedance, determine the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure.

[0097] In addition, when the logic commands in the foregoing memory are implemented in the form of software function units and sold or used as independent products, they may be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, may be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several commands for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs that can store program codes.

[0098] The processor in the electronic device provided in the embodiments of the present invention may call the logic instructions in the memory to implement the foregoing method. The specific implementation manner is the same as that of the foregoing method embodiment and can achieve the same beneficial effects, which will not be elaborated here.

[0099] The embodiments of the present invention also provide a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it is configured to execute the methods provided in the foregoing embodiments.

[0100] The specific implementation manner is consistent with the foregoing method implementation manner and can achieve the same beneficial effects, which will not be elaborated here.

[0101] An embodiment of the present invention provides a computer program product, including a computer program, which when executed by a processor implements the method as described above.

[0102] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative labor.

[0103] Through the description of the above implementation manners, those skilled in the art can clearly understand that each implementation manner can be realized by means of software plus a necessary general hardware platform, and of course also by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product, which can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vehicle-mounted antenna, characterized in that, It includes a circuit board, as well as an antenna module and an impedance matching module printed on the circuit board; The antenna module and the impedance matching module are determined based on the following steps: Based on the height of the signal trace on the circuit board from the reference ground plane and the thickness of the signal trace, determine the width of the signal trace of the antenna module; Based on the dielectric constant of the circuit board and the signal wavelength of the antenna module, determine the length of the signal trace of the antenna module; Based on the width and length of the signal trace, perform electromagnetic field simulation on the antenna module to determine the input impedance of the antenna module; Based on the input impedance of the antenna module, determine the device parameters of each device in the impedance matching module.

2. The vehicle-mounted antenna according to claim 1, wherein The trace shape of the antenna module is serpentine.

3. The vehicle-mounted antenna according to claim 1, characterized in that, The circuit board is a double-layer circuit board; the intermediate medium of the circuit board is glass fiber reinforced epoxy resin.

4. An impedance matching method, characterized in that, Applied to the vehicle-mounted antenna according to any one of claims 1 to 3, it includes: Obtain the input impedance of the antenna module in the vehicle-mounted antenna, and determine the coordinate point of the input impedance in the Smith chart; Move the coordinate point of the input impedance to the center position in the Smith chart, and determine the moving direction and moving distance of the coordinate point of the input impedance; Based on the moving direction and moving distance of the coordinate point of the input impedance, determine the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure.

5. The impedance matching method according to claim 4, wherein The determining the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure based on the moving direction and moving distance of the coordinate point of the input impedance includes: In the case where the moving direction is to move along the constant resistance circle in the clockwise direction, add a series inductor in the impedance matching module; In the case where the moving direction is to move along the constant conductance circle in the counterclockwise direction, add a parallel inductor in the impedance matching module; In the case where the moving direction is to move along the constant resistance circle in the counterclockwise direction, add a series capacitor in the impedance matching module; In the case where the moving direction is to move along the constant conductance circle in the clockwise direction, add a parallel capacitor in the impedance matching module.

6. The impedance matching method according to claim 4, wherein After determining the circuit structure of the impedance matching module in the vehicle-mounted antenna and the device parameters of each device in the circuit structure, the method further includes: Determine a plurality of parameter scaling factors; Perform a multiplication operation on the device parameters of each device and each parameter scaling factor to determine a plurality of candidate device parameters of each device; Based on the antenna scattering parameter curves of each device when obtaining each candidate device parameter, determine the optimal parameter scaling factor corresponding to each device; Based on the optimal parameter scaling factor corresponding to each device, determine the optimized device parameter corresponding to each device.

7. The impedance matching method according to claim 6, wherein The determining the optimal parameter scaling factor corresponding to each device based on the antenna scattering parameter curves of each device when obtaining each candidate device parameter includes: Analyze the antenna scattering parameter curves of each device when obtaining each candidate device parameter, and determine the correlation coefficient between the change of the parameter scaling factor and the change of the antenna scattering parameter; When the correlation coefficient is greater than a preset correlation threshold, determine the parameter scaling factor corresponding to the minimum value of the antenna scattering parameter as the optimal parameter scaling factor.

8. The impedance matching method according to claim 7, wherein After determining the correlation coefficient between the change of the parameter scaling factor and the change of the antenna scattering parameter, the method further includes: When the correlation coefficient is less than or equal to the preset correlation threshold, determine the frequency at which the minimum value of the antenna scattering parameter corresponding to each parameter scaling factor is located; When the frequency at which the minimum value of the antenna scattering parameter corresponding to any one parameter scaling factor is located is the resonant frequency of the antenna module, determine the any one parameter scaling factor as the optimal parameter scaling factor.

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the impedance matching method according to any one of claims 4 to 8.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the impedance matching method according to any one of claims 4 to 8.

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