Electromagnetic wave and Fresnel zone visualization teaching experiment system based on Wi-Fi

Abstract

The invention discloses a Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system, and the system comprises a simulation platform which is used for carrying out the simulation calculation according to preset electromagnetic wave propagation parameters, and generating a visual graph which comprises an electromagnetic wave waveform, interference fringes and / or Fresnel zone distribution; the simulation platform is used for simulating electromagnetic waves, the experiment platform is used for carrying out an electromagnetic wave propagation experiment in a physical space, and the control and display unit is in communication connection with the simulation platform and the experiment platform; wherein the control and display unit is configured to obtain real-time position information of the transmitting end, the receiving end and the reflecting end in the experiment platform, and send the position information and experiment parameters to the simulation platform; and receiving and synchronously displaying the visual graph generated by the simulation platform and the actually measured signal data acquired by the experiment platform. Simulation and experiments can be integrated, visualization of the electromagnetic wave phenomenon is achieved, and teaching is facilitated.

Description

Technical Field

[0001] This invention relates to the field of teaching instrument technology, and in particular to a Wi-Fi-based visual teaching experiment system for electromagnetic waves and the Fresnel zone. Background Technology

[0002] In the field of electromagnetism teaching, especially in the teaching practice of professional courses such as electromagnetic fields and electromagnetic waves, the reflection and interference phenomena of electromagnetic waves and the Fresnel zone concept are core knowledge points. These are highly abstract and require the help of experimental instruments to help students understand them intuitively.

[0003] Existing teaching experimental systems of this type have significant limitations: First, they do not achieve direct visualization of electromagnetic waves, only indirectly indicating their existence through changes in the brightness of lights, making it difficult for students to intuitively perceive waveforms, interference fringes, and the spatial distribution characteristics of the Fresnel region. Second, they lack a design that combines simulation and experimentation, preventing students from simultaneously comparing theoretical models with actual physical phenomena, leading to a disconnect between theory and practice. Third, they lack dedicated verification functions for Fresnel region phenomena, making it difficult for students to establish a connection between the Fresnel region and electromagnetic wave interference effects. Furthermore, some existing experimental instruments are complex in structure and cumbersome to operate, hindering rapid deployment and promotion in teaching settings and impacting the improvement of teaching effectiveness. Summary of the Invention

[0004] The purpose of this invention is to provide a Wi-Fi-based visual teaching experiment system for electromagnetic waves and the Fresnel zone. This invention integrates simulation and experimentation, enabling the visualization of electromagnetic wave phenomena and facilitating teaching.

[0005] The technical solution of this invention: A Wi-Fi-based visual teaching experiment system for electromagnetic waves and the Fresnel zone, comprising: The simulation platform is used to perform simulation calculations based on preset electromagnetic wave propagation parameters and generate visualization graphics that include electromagnetic wave waveforms, interference fringes, and / or Fresnel zone distributions. An experimental platform for conducting electromagnetic wave propagation experiments in physical space, the experimental platform including an electromagnetic wave emitting end, an electromagnetic wave receiving end, and a movable reflecting end; The control and display unit is communicatively connected to both the simulation platform and the experimental platform. The control and display unit is configured to: acquire the real-time position information of the transmitter, receiver and reflector in the experimental platform, and send the position information and experimental parameters to the simulation platform; receive and synchronously display the visualization graphics generated by the simulation platform and the measured signal data collected by the experimental platform.

[0006] The aforementioned Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system includes a touch screen in its control and display unit; the bottom of the transmitting end, receiving end, and reflecting end are provided with sensing structures for interacting with the touch screen. The touch screen is configured to detect the placement of the transmitter, receiver and reflector on the screen through capacitive sensing in order to determine their relative positions in the experimental space.

[0007] The aforementioned Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system integrates the simulation platform into the control and display unit and is equipped with a graphical user interface. The graphical user interface includes a waveform display area and a console area; The waveform display area is used to display the simulated electromagnetic wave waveform, interference fringes, and / or Fresnel zone ellipse; The console area is used to receive parameter adjustment instructions input by the user, and the parameters include at least electromagnetic wave frequency, transmission power, and reflection coefficient.

[0008] The aforementioned Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system further includes a positioning module, which is used to control the movement of the reflecting end on a preset path. The positioning module includes a guide rail and a slider that can slide along the guide rail, and the reflective end is fixed to the slider.

[0009] The aforementioned Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system also includes an electromagnetic shielding module, which is used to reduce the interference of stray electromagnetic waves in the environment on the experiment.

[0010] The aforementioned Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system, wherein the transmitting end and the receiving end are computer devices equipped with Wi-Fi network cards, and the operating frequency bands include 2.4GHz and / or 5GHz; The simulation platform is modeled based on electromagnetic wave interference and the Fresnel zone principle, and its algorithm includes: Calculate the path difference between the reflected path from the transmitter to the receiver via the reflector and the direct path from the transmitter to the receiver; Calculate the phase difference between the two electromagnetic waves based on the path difference and the wavelength of the electromagnetic wave. Based on the phase difference and the preset reflection coefficient, the electric field strengths of the direct wave and the reflected wave are superimposed to obtain the combined field strength. The signal amplitude at the receiving point is calculated based on the combined field strength, and the visualization graphic is generated accordingly.

[0011] In the aforementioned Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system, the calculation formula for complex superposition in the simulation platform algorithm is as follows: ; In the formula: It is a complex channel response; and These represent the losses along the direct path and the reflected path, respectively. The reflection coefficient, and These represent the phases of the direct path and the reflected path, respectively.

[0012] The aforementioned Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system further includes a control and display unit configured to: record the signal amplitude data measured by the receiving end when the reflecting end is at different positions, generate an experimental curve showing the change of signal amplitude with the position of the reflecting end, and compare and display it with the theoretical curve calculated by the simulation platform.

[0013] In the aforementioned Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system, the reflecting end is a metal reflector.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Achieve direct visualization of multiple physical phenomena: This invention generates visualized graphics of electromagnetic wave waveforms, interference fringes, and Fresnel zone distribution through a simulation platform. Combined with measured data collected from the experimental platform, it directly presents abstract electromagnetic wave reflection, interference effects, and Fresnel zone characteristics, significantly reducing the difficulty for students to understand core knowledge points.

[0015] 2. Achieving deep integration of simulation and experiment: The control and display unit of this invention synchronously links the simulation platform and the experimental platform, which can not only intuitively display theoretical laws through simulation models, but also verify the correctness of theories through actual measurement data, thus helping students establish a complete cognitive chain.

[0016] 3. Simplify experimental operations and enhance teaching applicability: The experimental platform uses common Wi-Fi devices as transmitters and receivers, along with a movable reflector and positioning module, resulting in a simple structure and controllable cost. The touch interaction design and parameter visualization adjustment function of the control and display unit lower the operating threshold and are suitable for various scenarios such as classroom teaching and experimental training.

[0017] 4. Intuitive data comparison enhances teaching effectiveness: The system can automatically record signal amplitude data at different positions of the reflecting end, generate experimental curves and compare them with the simulation theoretical curves, allowing students to clearly observe the fit between theory and practice and the reasons for the differences, thus deepening their understanding of the laws of electromagnetic wave propagation.

[0018] 5. Excellent scalability and practicality: It supports multi-band operation at 2.4GHz and / or 5GHz, and can be adapted to different teaching needs through parameter adjustment; the design of the electromagnetic shielding module reduces environmental interference, improves the accuracy and repeatability of experimental data, and has been recognized by multiple competitions, proving the practicality and innovative value of this invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the direct and reflected paths of electromagnetic waves; Figure 2 A schematic diagram of the Fresnel zone distribution and interference effect; Figure 3 This is a schematic diagram of the experimental platform structure. Figure 4 A visualization curve showing the subcarrier amplitude-reflection end position relationship from the first experiment; Figure 5 A visualization curve showing the subcarrier amplitude-reflection end position relationship in the second experiment; Figure 6 A visualization curve showing the subcarrier amplitude-reflection end position relationship in the third experiment; Figure 7 A visualization of the amplitude variance of electromagnetic waves; Figure 8 This is a system diagram under the ideal design conditions of the present invention.

[0020] Figure Labels 1. Transmitter; 2. Receiver; 3. Reflector; 4. Guide rail; 5. Slider; 6. Electromagnetic shielding module; 7. Control console; 8. Display screen. Detailed Implementation

[0021] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0022] Example: A Wi-Fi-based visualization teaching experiment system for electromagnetic waves and the Fresnel zone includes three core modules: a simulation platform, an experimental platform, and a control and display unit. The modules are connected through communication to form a collaborative working mechanism: the control and display unit acts as the core hub, acquiring the physical parameters of the experimental platform in real time and sending them to the simulation platform, and synchronously receiving simulation data and measured data and integrating and displaying them.

[0023] The simulation platform is integrated into the control and display unit (such as a Raspberry Pi hardware carrier). It uses electromagnetic wave interference and the Fresnel zone principle as its core to build a mathematical model, supporting multi-parameter adjustment and dynamic visualization output. The specific implementation method is as follows: 1. Core modeling principles; 1.1 Electromagnetic wave interference model: Based on the superposition effect of direct and reflected Wi-Fi waves, the propagation difference between the two paths is calculated, such as... Figure 1 As shown. Let the length of the direct path from the transmitter (T) to the receiver (R) be... The length of the reflection path from the transmitter to the receiver via the reflector (Q) is... Then the path difference Combined with Wi-Fi wave wavelength (Based on operating frequency) with the speed of light calculate, ), to obtain the phase difference caused by the path difference Phase abrupt change during superimposed reflection (for total internal reflection) ), final total phase difference .

[0024] 1.2 Calculation of Combined Electric Field Strength: According to the principle of electromagnetic wave superposition, the electric field strengths of the direct wave and the reflected wave are respectively: ; ; in: , These represent direct and reflected path losses, respectively. The reflection coefficient, , These represent the phases of the direct and reflected paths, respectively, and the combined field strength is the complex superposition of the two: ; Further calculation of the resultant amplitude As a quantitative indicator of signal strength.

[0025] 1.3 Fresnel zone modeling: like Figure 2 As shown, with the transmitter and receiver as the focal points, according to the Fresnel zone definition, "the first..." any point on the Fresnel zone boundary satisfy The visualization interface generates a Fresnel zone distribution pattern characterized by ellipses, where odd-numbered zones correspond to constructive interference (signal enhancement) and even-numbered zones correspond to destructive interference (signal attenuation), intuitively demonstrating the relationship between the Fresnel zone and the interference effect.

[0026] 2. Functional interface design; The graphical user interface of the simulation platform includes a waveform display area and a console area: Waveform display area: Real-time rendering of electromagnetic wave waveforms (sine curves), interference fringes (alternating bright and dark stripe patterns), and Fresnel zone ellipses (multi-layered concentric ellipses, labeled with the number of zones and interference type), supporting zoom and pan operations to observe local details; The console area provides a parameter input interface, allowing users to adjust parameters such as Wi-Fi wave frequency (2.4GHz / 5GHz), transmit power, reflection coefficient (real / imaginary part), and direct / reflected path loss. Adjustment commands are synchronized to the simulation model in real time, and the visualization graphics are dynamically updated.

[0027] (II) Experimental Platform: Physical experimental verification based on Wi-Fi devices; The experimental platform reproduces the electromagnetic wave propagation scenario in physical space, and collects measured data through adjustable hardware modules to provide physical verification for the simulation results, such as... Figure 3 As shown, it specifically includes the following components: 1. Core functional components; 1.1 Transmitter 1 and Receiver 2: Utilizing a computer device (such as a laptop) equipped with an Intel 5300 network card, supporting dual-band operation of 2.4GHz and 5GHz, and conforming to the Wi-Fi 802.11n standard (using OFDM encoding, containing 30 subcarriers with a subcarrier spacing of 312.5kHz). The transmitter outputs a stable Wi-Fi signal, and the receiver supports Channel State Information (CSI) reading, with a sampling frequency of 1000Hz, capable of real-time acquisition of signal amplitude data for each subcarrier, reflecting the actual signal strength at the receiving point.

[0028] 1.2 Reflecting end 3: It adopts a metal reflector (such as a 30cm×1.5cm aluminum strip, which has high conductivity and stable reflection performance). The bottom is equipped with a sensing structure (similar to the conductive contacts of a capacitive pen) that interacts with the touch screen. The real-time position can be identified by the display screen. The reflecting end is used to simulate the electromagnetic wave reflection scenario. Its position change directly changes the reflection path length, thus affecting the interference effect.

[0029] 1.3 Positioning Module: Includes a linear guide rail 4 with a length of 1m and an accuracy of 1mm and a sliding slider 5. The reflecting end 3 is fixed on the slider 5 and can move along the linear guide rail 4 on a preset path (such as the perpendicular bisector of the line connecting the transmitting end and the receiving end) to achieve precise control of the position of the reflecting end. The minimum movement step is 2cm to ensure the continuity and repeatability of experimental data.

[0030] 1.4 Electromagnetic shielding module 6: An aluminum mesh with a height of 50cm and a length of 82cm is fixed to the periphery of the experimental platform (such as behind the transmitter and receiver) to shield stray electromagnetic waves in the environment (such as interference signals from surrounding routers and electronic devices), reduce the impact of multipath effects on the measured data, and improve the accuracy of the experiment.

[0031] The system diagram under the ideal design of this invention can be referenced. Figure 8 .

[0032] 2. Experiment deployment logic; When deploying the experimental platform, use an infrared right-angle meter to calibrate the perpendicular relationship between the guide rail and the line connecting the transmitter and receiver to ensure that the guide rail is located on the perpendicular bisector of the line connecting the two; use a tape measure to fix the distance between the transmitter and receiver (e.g., 50cm), and raise the computer equipment to the same height as the reflector to avoid the desktop blocking the electromagnetic wave propagation path; surround the experimental area with an electromagnetic shielding module to reduce external electromagnetic interference and provide a stable physical environment for the experiment.

[0033] (III) Control and Display Unit: Multi-module collaboration and data integration; The control and display unit, as the "central hub" of the system, enables communication and linkage between the simulation platform and the experimental platform, data processing, and visualization output. Its specific functions are as follows: 1. Real-time location and parameter acquisition; Using a touch screen (capacitive screen) as the interaction medium, the sensor structure at the bottom of the transmitter, receiver and reflector is detected by capacitive sensing technology to accurately identify the relative positions of the three in the experimental space (positioning accuracy can reach 1mm); at the same time, the experimental parameters (such as frequency and reflection coefficient) input by the user through the console are received and the position information and experimental parameters are packaged and sent to the simulation platform to trigger simulation calculation.

[0034] 2. Data synchronization and comparison display; The system synchronously receives the visualization graphics (waveforms, interference fringes, Fresnel zone) generated by the simulation platform and the measured data (amplitude of each subcarrier, position-amplitude correspondence) collected by the experimental platform, and displays them in separate areas on the touch screen: the simulation visualization graphics are displayed on the left and the measured data curves are displayed on the right. It supports dual-screen linkage scaling, which facilitates intuitive comparison of the differences between theory and reality.

[0035] The system automatically records the measured signal amplitude data at different positions of the reflecting end, and generates experimental curves (sine-like curves) showing the change of signal amplitude with the position of the reflecting end using Python toolkits (such as Matplotlib). These curves are then overlaid on the theoretical curves (ideal curves calculated based on the summation amplitude formula) output by the simulation platform, and the positions of peaks and troughs and the corresponding interference types (constructive / destructive) are marked to help users quantitatively analyze the fit between theory and practice.

[0036] 3. Data storage and backtracking; It supports local storage of experimental data (such as storage to the Raspberry Pi's SD card), and the recorded content includes experimental parameters, reflector position sequence, measured amplitude data, simulation curve data and comparison results, which facilitates subsequent experimental review, data export and teaching report writing.

[0037] The typical workflow of the system of this invention is as follows: Step 1, Parameter Initialization: The user inputs experimental parameters (such as Wi-Fi frequency 5.320GHz, transmitter-receiver distance 50cm, reflection coefficient -0.9+0.1j) through the control and display unit's console. The touch screen identifies the initial positions of the transmitter and receiver and confirms that the positioning module calibration is complete. Step 2, Simulation Calculation and Display: The control and display unit sends the parameters to the simulation platform. The simulation platform completes the calculation based on the electromagnetic wave interference and Fresnel zone model, generates waveforms, interference fringes and Fresnel zone visualization graphics, and feeds them back to the touch screen for display. Step 3, Experimental Data Acquisition: The user moves the reflector to a preset position using the positioning module (e.g., from y=0cm to y=72cm, stopping every 2cm). The receiver collects the signal amplitude data at each position in real time and sends it to the control and display unit. Step 4, Data Comparison and Analysis: The control and display unit generates the measured position-amplitude curve, which is overlaid with the simulation theoretical curve and the interference extreme points are marked. Users can observe the curve fit and analyze the impact of environmental interference (such as scattered waves) and equipment errors (such as network card position deviation) on the experimental results, thereby deepening their understanding of the laws of electromagnetic wave propagation. Step 5, Data Storage and Review: After the experiment, the system automatically stores all experimental data and simulation results. Users can review the experimental curves under different parameters or export the data for teaching reports and research analysis.

[0038] Furthermore, this embodiment provides a systematic case study using a specific qualitative verification experiment of electromagnetic waves in the Fresnel zone.

[0039] (1) Raw data collection; The experiment was conducted in an open environment; only data was collected, and no plots were directly generated. Table 1-3 shows the data from three experiments regarding the location of the obstacle and the amplitude of 15 subcarriers (D=50cm, λ=6cm).

[0040] Table 1

[0041] Table 2

[0042] Table 3

[0043] (2) Data visualization; After the data collection is completed, all experimental data are fitted using cubic spline interpolation, which can better reflect the data trend. The core idea is to connect adjacent data points with cubic polynomials, while ensuring that adjacent polynomials have equal function values ​​and continuous first and second derivatives at the connection point, thus forming a smooth curve.

[0044] The result calculated using Python is as follows: Figure 4 , Figure 5 and Figure 6 As shown, the data correspond to Tables 1, 2, and 3, respectively. The horizontal axis represents the vertical distance from the aluminum plate to the midpoint of the line connecting the transmitter and receiver, and the vertical axis represents the subcarrier amplitude.

[0045] (3) Results analysis; In experimental settings, Wi-Fi wave interference is affected by direct waves, reflected waves, and scattered waves (multipath effect). By keeping all objects except obstacles stationary, the interference variation caused by a single object can be observed to the greatest extent (sine-like curves, such as...). Figure 4 , 5 As shown in Figures 6 and 7, the existence of the Fresnel zone in space was qualitatively observed, indicating that the experimental setup can accurately reflect the physical characteristics of the Fresnel zone. However, scattered waves increase multipath effects. When scattered waves, direct waves, reflected waves, and other signals with different paths reach the receiver, time differences (delays) occur due to different propagation distances, leading to signal superposition and interference. Furthermore, devices operating at the same frequency (such as routers) may overlap with Wi-Fi waves, causing interference to the experiment.

[0046] The sources of error in this example include systematic error, random error, and model error. The systematic error is a measurement error of several centimeters in the position of the laptop's built-in network card antenna, leading to distance inaccuracies. Random error arises from personnel moving the aluminum strip during the experiment; this can be reduced by repeating the experiment multiple times. Model error occurs because multiple reflection paths exist in the actual environment, affecting the superimposed amplitude. The error analysis experiment in this case is shown in Figure 7. The figure shows that the amplitude variances of different subcarriers differ significantly (e.g., the variance increases significantly around subcarriers 6-8), indicating that signal fluctuations in some frequency components are more severe. The curves of the three sets of experiments show roughly the same trend, but local values ​​differ, reflecting the impact of subtle changes in experimental conditions on signal stability. The overall variance fluctuates between 0.03 and 0.10, reflecting the amplitude fluctuation characteristics of Wi-Fi electromagnetic waves under multipath interference and environmental disturbances.

[0047] In summary, this invention not only directly presents abstract electromagnetic wave waveforms, interference fringes, and Fresnel zone characteristics through the visualization design of the simulation platform, significantly reducing the difficulty of understanding core knowledge points; it also achieves accurate reproduction of physical scenarios and data acquisition through the combination of Wi-Fi devices, positioning modules, and shielding modules in the experimental platform; and it enables synchronous comparison between simulation theory and measured data through the linkage mechanism of the control and display units, facilitating the establishment of a complete cognitive chain for students. Furthermore, the system uses common hardware, simplifies operation procedures, and supports multi-band adjustment, balancing practicality and scalability for teaching scenarios. The addition of the electromagnetic shielding module improves the accuracy of experimental data, while data storage and error analysis functions further enhance teaching effectiveness. Overall, it achieves multiple teaching values: making abstract knowledge intuitive, integrating theory and practice, and simplifying experimental operations.

Claims

1. A Wi-Fi-based visual teaching experiment system for electromagnetic waves and the Fresnel zone, characterized in that, include: The simulation platform is used to perform simulation calculations based on preset electromagnetic wave propagation parameters and generate visualization graphics that include electromagnetic wave waveforms, interference fringes, and / or Fresnel zone distributions. An experimental platform for conducting electromagnetic wave propagation experiments in physical space, the experimental platform including an electromagnetic wave emitting end, an electromagnetic wave receiving end, and a movable reflecting end; The control and display unit is communicatively connected to both the simulation platform and the experimental platform. The control and display unit is configured to: acquire the real-time position information of the transmitter, receiver and reflector in the experimental platform, and send the position information and experimental parameters to the simulation platform; receive and synchronously display the visualization graphics generated by the simulation platform and the measured signal data collected by the experimental platform.

2. The Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system according to claim 1, characterized in that, The control and display unit includes a touch screen; the bottom of the transmitter, receiver, and reflector is provided with a sensing structure for interacting with the touch screen; The touch screen is configured to detect the placement of the transmitter, receiver and reflector on the screen through capacitive sensing in order to determine their relative positions in the experimental space.

3. The Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system according to claim 1, characterized in that, The simulation platform is integrated into the control and display unit and is equipped with a graphical user interface; The graphical user interface includes a waveform display area and a console area; The waveform display area is used to display the simulated electromagnetic wave waveform, interference fringes, and / or Fresnel zone ellipse; The console area is used to receive parameter adjustment instructions input by the user, and the parameters include at least electromagnetic wave frequency, transmission power, and reflection coefficient.

4. The Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system according to claim 1, characterized in that, The experimental platform also includes a positioning module, which is used to control the movement of the reflective end on a preset path; The positioning module includes a guide rail and a slider that can slide along the guide rail, and the reflective end is fixed to the slider.

5. The Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system according to claim 4, characterized in that, The experimental platform also includes an electromagnetic shielding module, which is used to reduce the interference of stray electromagnetic waves in the environment on the experiment.

6. The Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system according to claim 1, characterized in that, The transmitter and receiver are computer devices equipped with Wi-Fi network cards, and the operating frequency bands include 2.4GHz and / or 5GHz; The simulation platform is modeled based on electromagnetic wave interference and the Fresnel zone principle, and its algorithm includes: Calculate the path difference between the reflected path from the transmitter to the receiver via the reflector and the direct path from the transmitter to the receiver; Calculate the phase difference between the two electromagnetic waves based on the path difference and the wavelength of the electromagnetic wave. Based on the phase difference and the preset reflection coefficient, the electric field strengths of the direct wave and the reflected wave are superimposed to obtain the combined field strength. The signal amplitude at the receiving point is calculated based on the combined field strength, and the visualization graphic is generated accordingly.

7. The Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system according to claim 6, characterized in that, In the algorithm of the simulation platform, the formula for calculating the superposition of complex numbers is: ； In the formula: It is a complex channel response; and These represent the losses along the direct path and the reflected path, respectively. The reflection coefficient, and These represent the phases of the direct path and the reflected path, respectively.

8. The Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system according to claim 1, characterized in that, The control and display unit is further configured to: record the signal amplitude data measured by the receiving end when the reflecting end is at different positions, generate an experimental curve of the signal amplitude changing with the position of the reflecting end, and compare and display it with the theoretical curve calculated by the simulation platform.

9. The Wi-Fi-based electromagnetic wave and Fresnel zone visualization teaching experiment system according to any one of claims 1-8, characterized in that, The reflective end is a reflective plate made of metal.

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