An antenna system includes an antenna and an antenna control apparatus. The antenna control apparatus includes a control circuit, i.e., a control integrated circuit. The control circuit adjusts and boosts an antenna voltage to supply a required current to the antenna. The antenna voltage is maintained so as not to exceed a predetermined upper limit voltage threshold value. The control circuit is configured to determine a disconnection failure on the antenna when the antenna voltage detected by an overvoltage detection circuit reaches the upper limit voltage threshold value, or is boosted beyond the upper limit voltage threshold value.