regarding the distance for the bluetooth range for scan and advertisement for nrf52840

Hi Nordic,

I am using the two nrf52840 units to test adv and scanning in a pair for the development. I am using BLE_GAP_PHY_CODED for both scan and advertisement. But when I test it, seems the package lost get very high when distance is longer than 70 meters. Any way to improve it? Also, is it possible to use the antenna signal amplifer for improve the receiving and advertisement distance?