Antenna apparatus

An antenna apparatus comprising:

• a first radiation element to receive a first left-hand circularly polarized wave and a first right-hand circularly polarized wave;
• a second radiation element to receive a first left-hand circularly polarized wave and a first right-hand circularly polarized wave;
• a first phase shifter to shift a phase of a first left-hand circularly polarized wave signal representing the first left-hand circularly polarized wave received from the first radiation element;
• a second phase shifter to shift a phase of a second left-hand circularly polarized wave signal representing the first left-hand circularly polarized wave received from the second radiation element;
• a third phase shifter to shift a phase of a first right-hand circularly polarized wave signal representing the first right-hand circularly polarized wave received from the first radiation element;
• a fourth phase shifter to shift a phase of a second right-hand circularly polarized wave signal representing the first right-hand circularly polarized wave received from the second radiation element;
• and
• a control circuit configured to estimate first polarization angles of the first left-hand circularly polarized wave and the first right-hand circularly polarized wave based on a difference between a phase of the first left-hand circularly polarized wave signal and a phase of the first right-hand circularly polarized wave signal or a difference between a phase of the second left-hand circularly polarized wave signal and a phase of the second right-hand circularly polarized wave signal, wherein
• the control circuit estimates first arrival directions of the first left-hand circularly polarized wave and the first right-hand circularly polarized wave based on a difference between a phase of the first left-hand circularly polarized wave signal and a phase of the second left-hand circularly polarized wave signal or a difference between a phase of the first right-hand circularly polarized wave signal and a phase of the second right-hand circularly polarized wave signal, and
• the control circuit determines a first phase shift amount in the first phase shifter, a second phase shift amount in the second phase shifter, a third phase shift amount in the third phase shifter, and a fourth phase shift amount in the fourth phase shifter based on the first polarization angles and the first arrival directions.

An antenna apparatus comprising:

• a processing circuit configured to determine a polarization angle and a radiation direction of a radio wave to be radiated and generate left-hand circularly polarized wave information indicating a left-hand circularly polarized wave and right-hand circularly polarized wave information indicating a right-hand circularly polarized wave, the left-hand circularly polarized wave information and the right-hand circularly polarized wave information each having a phase corresponding to the polarization angle and the radiation direction;
• a conversion circuit to convert the left-hand circularly polarized wave information to a left-hand circularly polarized wave signal and convert the right-hand circularly polarized wave information to a right-hand circularly polarized wave signal;
• and
• a plurality of radiation elements to radiate a left-hand circularly polarized wave and a right-hand circularly polarized wave in response to the left-hand circularly polarized wave signal and the right-hand circularly polarized wave signal.