Electromagnetic interference with medical devices from third generation mobile phone including LTE

This paper describes Electromagnetic Interference (EMI) with medical devices used in hospitals from third generation mobile phone. Transmission power, frequency, radiation mode, and radiation sources are considered to investigate the relationship with EMI. Long Term Evolution (LTE), High Speed Packet Access (HSPA), and Wideband Code Division Multiple Access (W-CDMA) are selected as the transmission method because they are widely spread over the world. Thirty-two different medical devices, which are mainly used in the operating room or Intensive Care Unit, are used in this evaluation. The results show that 12 medical-device models (37.5%) incurred EMI. The results also clearly show that the EMI strongly depends on the transmission power and the distance between the mobile phone and medical device. For example, when transmission power at 800 MHz is the nominal maximum and 10 dBm, the maximum EMI distances are approximately 70 and 10 cm, respectively. Based on this, the nominal maximum power test is important for conservative evaluation. On the other hand, the results do not show that EMI is dependent on the frequency band. Therefore, evaluations must consider all mobile phone frequency bands so that EMI can be property detected. Furthermore, the electromagnetic field emitted by a half-wave dipole antenna causes higher levels of EMI than that by a mobile phone. Since characteristics of a half-wave dipole antenna are well known, reliable and reproducible evaluations are expected. One possible EMI test procedure is to use a half-wave dipole antenna in order to determine the evaluation conditions for actual mobile phones. Finally, in terms of the radiation mode, we show that discontinuous radiation might cause higher levels of EMI than those for continuous radiation.