Turning Yamanote Line trains into 5G millimeter-wave zones: JR East and KDDI conduct first proof test, sending radio waves into the car with glass antennas

JR East and KDDI conducted a proof of concept to extend 5G millimeter-wave coverage inside Yamanote Line train cars.

Using glass antennas on the windows to receive and amplify millimeter waves, they re-radiated the signal into the car interior.

They confirmed 1Gbps-class communication across about 97% of the vehicle, showing strong potential for in-train connectivity.

The result could help improve wireless quality in hard-to-reach spaces like railway cars and broaden the use of high-speed mobile networks.