Proposals for Saving Power and Improving Efficiency in Radiated Fields in Close Proximity Immunity Testing Required for Medical Electrical Equipment

The medical electrical equipment standard, JIS T0601-1-2:2023 (JIS T0601-1-2), has been published. Furthermore, under the Pharmaceutical and Medical Device Act, medical devices marketed in Japan after February 25, 2026, will be required to confirm compliance with JIS T0601-1-2. This standard has added a requirement for verifying compliance with radiated fields in close proximity immunity standard stipulated in the basic standard IEC 61000-4-39:2017. Radiated fields in close proximity immunity is intended to prevent electromagnetic interference in devices that use magnetic fields, such as induction heating equipment, RFID, and anti-theft gates. In this study, we propose a method to improve the efficiency of radiated electromagnetic fields in proximity immunity tests by saving the power loss caused by the impedance mismatch between the power amplifier and the radiating loop antenna. As a result, an impedance conversion circuit using a transformer was proposed for a wideband matching circuit from 150kHz to 26MHz, and the power consumption was improved from 135W without a matching circuit to 36.3W by using the matching circuit developed in this study. Saving power consumption is economically effective. The usefulness of the matching circuit developed in this study became clear.