An antenna system includes an antenna array, a wireless transceiver module and a control module. The antenna array includes a first antenna and a second antenna coupled respectively to the wireless transceiver module. The wireless transceiver module sends and receives signals via the first antenna based on a first phase and sends and receives signals via the second antenna based on a second phase. The control module coupled to the wireless transceiver module, and controls the phase difference between the first phase and the second phase. The radiation pattern of the antenna array is modulated towards one pointing direction based on the phase difference.