Electromagnetic Interference Issues of Aircraft Radio Altimeters Due to Sub-6 Band 5G Mobile Communications Systems in Japan

Electromagnetic interference (EMI) issues of the aircraft radio altimeter (RA) due to Sub-6 band 5G mobile communication system in Japan is discussed based on the experimental results. Sub-6 band 5G mobile commutation systems have been adopted globally. However, in Japan, the guard band between RAs and 5G mobile commutation systems is 100 MHz, which is lower than that in most other countries. In this study, we investigated EMI in aircraft RAs due to Sub-6 band 5G mobile communication systems in Japan. First, the EMI characteristics of RAs are measured under a narrow guard band. Next, the interference tolerance mask (ITM) is calculated from the measured interference thresholds. Finally, the obtained ITMs are compared with those reported under wider guard bands. The results confirm that Japan has a higher risk of interference than the United States and France because of the narrower guard band in Japan.