An antenna system includes: a plurality of antennas; a switching unit, having a plurality of switches, wherein each of the plurality of switches and the corresponding antenna are in a conducting state or in a non-conducting state; a communication unit, connected with each of the plurality of switches of the switching unit, and coupled with the antennas, wherein the communication unit receives a reference value group of the corresponding antenna from the switch in the conducting state; and a control unit, connected with the switching unit and the communication unit, wherein the control unit receives the reference value group from the communication unit, and compares the reference value group with an threshold, to determine whether the reference value group conforms to a pre-determined condition or not, and outputs a restarting instruction to restart the switching unit when the reference value group does not satisfy the pre-determined condition.