An antenna apparatus includes a number of antenna devices disposed to surround a center. M switches are connected to the plurality of antenna devices, M being an integer equal to or greater than 1. The of antenna devices include N antenna device groups and each of the N antenna device groups includes M antenna devices. N is an integer equal to or greater than 1. For each of the M switches, the mth switch is connected to the mth antenna device of the each of the N antenna device groups, m being an integer ranging from 1 to M.