A base station device provided with a plurality of antennas has a mode, in
which all the antennas are used, and a mode, in which the plurality of
antennas are divided into a plurality of groups each including two or
more antennas to be used independently. An array antenna pattern is
formed selectively in these modes. When the array antenna pattern is to
be formed in the mode of using all the antennas, a signal of one
synthesizer is applied to transmission/reception circuits of all the
antennas. In the mode of using antennas divided into the plurality of
groups, signals of different synthesizers are supplied to the
transmission/reception circuits of the antennas.