And when the array transmits back to the cell-phone user, the processor sends an out-of-phase signal to one of the antennas, generating a radio beam that runs from north to south.

• 当阵列发射讯号给行动电话用户时，处理器会传送一个异相的讯号到其中一个天线，产生由北往南的无线电波束。