Magnetic field maps of an astable multivibrator in frequency range from 100 kHz to 50 MHz

The data presents a result of near field measurements of electromagnetic emissions radiated from the PCB of a small electronic device.  An efficient method of modelling the magnetic and electric field emissions is the measurements in the near field using electric and magnetic probes. The attached files contain magnetic field maps created on based measurements using H-field Probe LF-B 3 in the frequency range 100 kHz – 50 MHz.  The designated maps enable the location of the sources of high magnetic fields radiated by the tested device. The device under test (DUT) was a typical astable multivibrator supplied from a battery of 9 V (Fig. 1).
Twenty-five measurement points are marked on the PCB, located exactly above the elements of the DUT (Fig. 2). The near fields were measured directly on the surface of PCB. The probe was placed at the same distance from the PCB surface, regardless of the height of the elements. The probe LF-B 3 is a passive near-field probe. It detects magnetic field lines emitted from the measured object at 90°. Magnetic field lines, which enter the probe laterally, are not detected. The probes provide a high resolution of less than 2 mm. The average value of the voltage at the probe output was measured at all points with an oscilloscope. Each measurement was performed for the averaged instantaneous values (the number of averages above 300) for both the background, i.e. the device turned off and the device turned on. All results of measurements made with near field probes are presented in mV. This is due to the measurement of the voltage at the output of the probe for both electric and magnetic fields. In Figure 3, the near-field measurement system developed to measure the radiated emission is shown.
The attached files contain magnetic field maps and the table with the measurement results. Figure 1. The electronic diagram of the AVT 720 device Figure 2. Arrangement of measurement points on the DUT Figure 3. The near-field measurement system

本数据集呈现了一款小型电子设备印刷电路板（PCB，Printed Circuit Board）辐射电磁发射的近场测量结果。针对磁场与电场辐射开展建模的一种高效方法，是利用电、磁场探针开展近场测量。附件包含基于H场探针LF-B 3在100 kHz – 50 MHz频率范围内开展测量所生成的磁场分布图。该磁场分布图可用于定位被测设备辐射的强磁场源。本次测试的设备（DUT，Device Under Test）为一款典型的无稳态多谐振荡器，由9V电池供电（见图1）。
PCB表面标记有25个测量点位，精准对应被测设备各元器件的正上方（见图2）。近场测量直接在PCB表面进行，探针与PCB表面的间距保持固定，不受元器件自身高度的影响。探针LF-B 3属于无源近场磁探针，可捕捉被测对象辐射出的与探针呈90°夹角的磁场线，沿探针侧面入射的磁场线则无法被探测。该探针具备小于2 mm的高分辨率。使用示波器对所有点位的探针输出电压平均值进行了测量。每一组测量均针对设备断电（背景状态）与通电两种工况下的瞬时平均数值开展，平均次数均超过300次。所有近场探针测量结果均以毫伏（mV）为单位，这是因为该探针的输出电压可同时表征电场与磁场的强度。图3展示了本研究搭建的辐射发射近场测量系统。
附件包含磁场分布图与测量结果数据表。
图1：AVT 720设备的电子电路图
图2：被测设备上的测量点位排布
图3：近场测量系统