Interference Feature of Square-Wave Modulated Single-Frequency Signal to Regulated Power Supply

To explore the advantages and limitations of employing square-wave modulated single-frequency signals in electric field radiated susceptibility testing, critical interference effect tests using both single-frequency continuous waves and square-wave modulated single-frequency radiation fields were conducted, respectively, at four susceptible frequencies (98, 262, 326, 404 MHz) of a linear voltage regulator and two susceptible frequencies (26, 36 MHz) of a switching-mode power supply. The variation law of critical interference field strength according to the modulation period was determined. The test results demonstrate that the output interruption in the tested power supplies was not only determined by the interference field strength and frequency but also significantly influenced by the repetition period of the interference signal. Square-wave modulated single-frequency interference provides superior characterization of the time-domain response characteristics of the equipment under testing when compared to conventional single-frequency continuous wave interference. However, RS103 only employs a modulated signal with a 1 ms repetition period, making it insufficient to fully characterize the actual susceptible characteristics of the tested equipment. Therefore, it requires supplementary evaluation through critical interference testing using single-frequency continuous waves.