Antenna device

An antenna device comprising:

• a waveguide section forming a waveguide path to propagate radio waves;
• and
• a cavity section forming a cavity to communicate with the waveguide path via a power supply opening located on one side of the waveguide section in a first direction, wherein
• the cavity section includes
• a first wall having the power supply opening and facing the cavity from the other side opposite to the one side in the first direction,
• a second wall opposing the first wall and having a plurality of radiation apertures, the second wall facing the cavity from the one side in the first direction, and
• a side wall that connects the first wall and the second wall to surround the cavity between the first wall and the second wall,
• the plurality of radiation apertures communicate the cavity and an external space to propagate the radio waves between the cavity and the external space, the plurality of radiation apertures having at least three apertures arranged in a second direction perpendicular to the first direction,
• in a first cross section along the first direction and the second direction, the side wall has a second-direction changing surface on one side and the other side of the power supply opening in the second direction to face the cavity such that a distance from the power supply opening in the second direction increases toward the one side in the first direction,
• the second-direction changing surface is shaped so that variations in phase of the radio waves at the plurality of radiation apertures are reduced when the radio waves of a predetermined wavelength are propagated from the power supply opening to the cavity, in comparison with a case where the second-direction changing surface is not provided in the first cross section such that the distance from the power supply opening to the side wall in the second direction is constant,
• the plurality of radiation apertures includes at least two apertures arranged in a third direction perpendicular to both the first direction and the second direction,
• the antenna device further comprising at least one third-direction partition wall protruding from the second wall into the cavity at position between the radiation apertures adjacent to each other in the third direction,
• the third-direction partition wall has a tip on the other side in the first direction,
• the cavity has compartment spaces partitioned by the third-direction partition wall,
• the cavity has a communication portion that connects the compartment spaces adjacent to each other, and
• the communication portion is located on the other side of the tip of the third-direction partition wall in the first direction.