Antenna device and antenna excitation method

An antenna excitation method of exciting a plurality of sub array antennas each including a plurality of element antennas for receiving signals and a plurality of phase shifters for adjusting excitation phases of said element antennas, said antenna excitation method comprising the steps of:

• in an excitation phase changing unit, changing the excitation phases of said plurality of element antennas by controlling said plurality of phase shifters;
• in each of a plurality of electric power combining units disposed respectively for said plurality of sub array antennas, combining a plurality of received signals of the plurality of element antennas included in a corresponding one of said sub array antennas into a composite signal, and outputting said composite signal;
• in a signal combining unit, generating a sum signal by in-phase combining the composite signals outputted from said plurality of electric power combining units, and also generating a difference signal by out-of-phase combining the composite signals outputted from said plurality of electric power combining units;
• and
• in a radiation pattern forming unit, shifting phases of the sum and difference signals generated by said signal combining unit every time the excitation phases are changed by said excitation phase changing unit, forming a radiation pattern associated with a sum pattern by time-integrating the sum signal after phase shift, and also forming a radiation pattern associated with a difference pattern by time-integrating the difference signal after phase shift.