Antenna

1. An antenna comprising:

a feeder circuit layer in which a waveguide entrance and a first waveguide through which a radio wave is propagated are formed;

an antenna layer in which a plurality of antenna elements are formed; and

a coupling layer that is formed between the feeder circuit layer and the antenna layer and couples the first waveguide to the plurality of antenna elements with a waveguide, wherein

the plurality of antenna elements include a first antenna element, a second antenna element, and a third antenna element, the second and third antenna elements being adjacent to the first antenna element,

the first and second antenna elements are arranged in such a manner that centers of the first and second antenna elements are aligned in a first direction parallel to a principal surface of the antenna layer,

the third antenna element is arranged in such a manner that the third antenna element is separated from the first antenna element in a second direction and centers of the first and third antenna elements are not aligned in the second direction, the second direction being parallel to the principal surface of the antenna layer and perpendicular to the first direction,

in the coupling layer, a second waveguide that connects the first antenna element and the first waveguide to each other and a third waveguide that connects the third antenna element and the first waveguide to each other are formed, and

a distance between a first connection end that connects the first waveguide and the second waveguide to each other and the waveguide entrance formed in the feeder circuit layer is equal to a distance between a second connection end that connects the first waveguide and the third waveguide to each other and the waveguide entrance formed in the feeder circuit layer.

2. The antenna according to claim 1 , wherein

a center of the first connection end and a center of a third connection end that connects the first antenna element and the second waveguide to each other are separated from each other in the first direction by a first value, and

a center of the second connection end and a center of a fourth connection end that connects the third antenna element and the third waveguide to each other are separated from each other in a direction opposite to the first direction by the first value.

3. The antenna according to claim 1 , wherein the plurality of antenna elements are formed in a size equal to or greater than a wavelength of a radiated wave.

4. The antenna according to claim 1 , wherein the plurality of antenna elements each have a pyramidal shape with a vertex facing the coupling layer.

5. The antenna according to claim 4 , wherein the plurality of antenna elements each have a quadrangular pyramid shape with a vertex facing the coupling layer.

6. The antenna according to claim 5 , wherein

openings of the plurality of antenna elements that are located at a side opposite to the coupling layer have a square shape, and

a length of a side of the square shape is equal to or more than a wavelength of a radiated wave.

7. The antenna according to claim 1 , wherein the plurality of antenna elements are arranged in a staggered manner.

8. The antenna according to claim 1 , wherein the second and third waveguides are formed in a multi-stage crank shape.