The standard radiated immunity test of an astable multivibrator at a normative field strength

The dataset presents a result of measurements that are a part of electromagnetic field immunity tests. The radiated, radio frequency, immunity tests were carried out for a typical astable electronic multivibrator. Tests of immunity of electronic systems to radiated radio frequency (RF) disturbances in the frequency range from 80 MHz to 1 GHz are performed under the requirements specified in the electromagnetic compatibility (EMC) standards.In laboratory conditions, the electromagnetic fields were simulated in the GTEM (Gigahertz Transverse Electromagnetic) cell (Fig. 1). An integrated signal generator, equipped with a built-in 45 W class A power amplifier module, was used in the measurement setup. The tested multivibrator was supplied from a battery of 9 V or externally from the NN DF1723003TC power supply. The signal cable connected to the input of an oscilloscope was led out of the tested PCB. The measurement process was controlled by the WIN 6000 software installed on a personal computer connected to the signal generator via the IEEE488 interface. Figure 1. Configuration of the measuring system for testing the immunity of electronic systems in the GTEM cell
A typical astable multivibrator built on bipolar transistors T3 and T4 was subjected to the immunity test (Fig. 2). The proper operation of the device is showed by flashing LEDs with variable frequency. A signal wire was led out from the collector of the transistor T3 and connected to the oscilloscope input. The system sensitivity to the radiated field in the GTEM cell was assessed based on the observation of the changes in the shape of the signal waveform controlling diode switching.
The normative test procedure was carried out in the frequency range starting at 80 MHz and incrementing in 1% steps up to at least 1 GHz. The RF signal was modulated with a sinusoidal signal with a frequency of 1 kHz and a modulation depth of 80%. Immunity tests were made for three different levels of the electromagnetic field strength 1 V/m, 3 V/m and 10 V/m, respectively. The position of the equipment under test in the uniform area of the GTEM cell was changed for three orthogonal orientations x, y, z (Fig. 3). During the measurements, on the oscilloscope, the differences in the shape of the voltage waveform to the reference waveforms recorded with the signal generator turned off were being observed. The attached files contain oscillograms showing the voltage waveforms from the PCB that deviate the most from the reference waveform. For each case, information about the RF frequency of the signal generator is included in the file description. Figure 2. The electronic diagram of the AVT 720 system Figure 3. The schematic diagram of a GTEM cell. Presented dimensions are for Teseq GTEM 500