Antenna apparatus
Provided is an antenna apparatus including a waveguide that extends in a first direction and at least one ridge that protrudes from an inner peripheral surface of the waveguide and extends in the first direction, the at least one ridge including a first ridge part that protrudes from the inner peripheral surface of the waveguide toward a central axis of the waveguide and a second ridge part that protrudes from an end of the first ridge part toward the inner peripheral surface of the waveguide.
1 . An antenna apparatus comprising:
a waveguide that extends in a first direction; and
at least one ridge that protrudes from an inner peripheral surface of the waveguide and extends in the first direction,
wherein the at least one ridge includes:
a first ridge part that protrudes from the inner peripheral surface of the waveguide toward a central axis of the waveguide; and
a second ridge part that protrudes from an end of the first ridge part toward the inner peripheral surface of the waveguide,
wherein the second ridge part protrudes toward the inner peripheral surface of the waveguide in a second direction and a third direction that is symmetrical with the second direction about a straight line including the first ridge part on a plane intersecting the first direction,
wherein the second ridge part includes a first portion having a first protruding length protruding in the second direction and the third direction along the first direction, and a second portion having a second protruding length protruding in the second direction and the third direction are a second length, and
wherein the at least one ridge has a mushroom-shape structure that is configured for miniaturization and lower cut-off frequency.
2 . The antenna apparatus of claim 1 , wherein a length in which the second ridge part protrudes in the second direction and a length in which the second ridge part protrudes in the third direction are identical to each other.
3 . The antenna apparatus of claim 1 , wherein the second portion includes a portion where the second length gradually decreases from the first length in the first direction.
4 . The antenna apparatus of claim 1 , wherein the second ridge part includes the first portion having a first protruding length protruding in the second direction and the third direction along the first direction, and a second portion having a second protruding length protruding in the second direction and the third direction are the second length, and
wherein the first ridge part includes a third portion having a third protruding length protruding from the inner peripheral surface of the waveguide toward the central axis of the waveguide, and a fourth portion having a fourth length protruding toward the central axis of the waveguide.
5 . The antenna apparatus of claim 4 ,
wherein the second portion includes the portion where the second length decreases from the first length in the first direction, and
wherein the fourth portion includes a portion where the fourth length gradually decreases from the third length in the first direction.
6 . The antenna apparatus of claim 1 , further comprising:
an iris structure that protrudes from the inner peripheral surface of the waveguide along the plane intersecting the first direction.
7 . The antenna apparatus of claim 6 , wherein the iris structure includes a fifth portion where a length protruding from the inner peripheral surface of the waveguide decreases in the first direction.
8 . The antenna apparatus of claim 1 , wherein the at least one ridge is provided in a plurality of odd numbers and provided symmetrically about the central axis of the waveguide.
9 . The antenna apparatus of claim 1 , wherein the waveguide has a shape of a hollow polygonal pillar or a hollow cylinder.