The Influence of Self-Electromagnetic Interference on Shielding effectiveness Measurement and Countermeasure

In the process of shielding effectiveness measurement, different levels of electromagnetic interference were found in different frequency bands. Preliminary analysis attributed this interference to the electronic devices within the automated testing system. Following GJB 151B-2013, the electromagnetic radiation characteristics of the interference source were measured in the 30 MHz-6 GHz frequency range. The frequency bands of the electromagnetic radiation in the measurement results matched those of the electromagnetic interference in the shielding effectiveness measurement. To address this electromagnetic interference, a portable shielding tent was further used to shield and suppress the electronic devices in the system. Radiation characteristic measurements were conducted on the shielding effectiveness measurement system after shielding, and no significant electromagnetic radiation was found, successfully suppressing the electromagnetic radiation from the electronic devices. Finally, an analysis of the shielding effectiveness measurement results before and after shielding showed that the measurement system regained the accuracy of the shielding effectiveness measurement results after shielding.