How to improve elevator signal coverage solutions?

The elevator space is small, the elevator shaft is surrounded by reinforced concrete and reaches a height of tens of meters. The elevator car lift and elevator doors are all made of metal, which greatly attenuates the mobile phone signal. If a signal amplifier is not installed to cover the mobile phone signal in the car lift, Cell phones cannot be used normally in the elevator.

C17L signal amplifier is installed in the elevator machine room, and a Log periodic antenna is used as the Donor antenna, which is installed outside the elevator machine room toward the base station tower. If the total height of the elevator shaft exceeds 50 meters, an A17L series elevator signal amplifier needs to be installed on the top of the car lift, and a low-gain panel antenna is used as the service antenna to radiate the interior of the car lift, and a Log periodic antenna with good directivity is used as the the Donor antenna which faces the elevator shaft and receive the signal from the base station in the shaft. The system diagram is as follows: