Waveguide, method of manufacturing waveguide and antenna

1. A waveguide having a first conductor plate and a second conductor plate in contact with the first conductor plate, wherein

the first conductor plate includes:

a groove portion that has a rectangular cross section and is formed parallel to a first main surface, which is a flat surface of the first conductor plate on the second conductor plate side, such that a longitudinal direction of the groove portion is a first direction; and

a first vertical tube portion formed in a direction away from the second conductor plate in a second direction, which is orthogonal to the first direction and the first main surface, starting from a branch position in the groove portion; and

the second conductor plate includes a reflective portion that is inserted into the groove portion and protrudes from a second main surface, which is a flat surface of the second conductor plate in contact with the first main surface, and has a reflective surface which reflects a radio wave, propagated along the groove portion, toward the first vertical tube portion.

2. The waveguide according to claim 1 , wherein

the reflective surface has a reflective region positioned between i) a position in the first direction of a surface of the first vertical tube portion closest to a side where the radio wave is incident and ii) a position in the first direction of a surface of the first vertical tube portion farthest from the side where the radio wave is incident.

3. The waveguide according to claim 1 , wherein

a position in the first direction of a first end portion of the reflective surface on the first conductor plate side is the same as a position in the first direction of a surface of the first vertical tube portion farthest from an incident side where the radio wave is incident;

a position in the first direction of a second end portion of the reflective surface, which is opposite to the first end portion, is between a position in the first direction of a surface of the first vertical tube portion closest to the incident side and a position in the first direction of a surface of the first vertical tube portion farthest from the incident side.

4. The waveguide according to claim 1 , wherein

the second conductor plate further includes a second vertical tube portion that extends in the second direction, from an end portion of the groove portion opposite to a side where the first vertical tube portion is formed, and penetrates through the second conductor plate.

5. The waveguide according to claim 1 , wherein

in a case where an inner width of the waveguide as defined by a rectangular waveguide standard is Wa [mm] and a light speed is C0 [10 6 m/s]:

a frequency of the radio wave is 1.4×C0/(2×Wa) [GHz] or more and 1.7×C0/(2×Wa) [GHz] or less; and

a distance between an outer surface of the reflective portion parallel to the first direction and an inner surface of the groove portion parallel to the first direction is equal to or greater than 12% and less than 38% of a distance between two inner surfaces of the groove portion.

6. A method of manufacturing a waveguide, comprising:

forming, in a first conductor plate material, a groove portion that has a rectangular cross section such that a longitudinal direction of the groove portion becomes a first direction and the groove portion is parallel to a first main surface of the first conductor plate material;

manufacturing a first conductor plate by forming, in the first conductor plate material, a vertical pipe portion extending in a second direction, which is orthogonal to the first direction and the first main surface, starting from a branch position in the groove portion;

a step of manufacturing a second conductor plate by forming, in a second conductor plate material different from the first conductor plate material, a reflective portion having a reflective surface for reflecting a radio wave, propagated along the groove portion, toward the vertical tube portion, such that the reflective portion protrudes from a second main surface of the second conductor plate material in contact with the first main surface; and

coupling the first conductor plate and the second conductor plate such that the first main surface and the second main surface are in contact with each other in a state where the reflective portion is inserted into the groove portion, after forming the first conductor plate and the second conductor plate.

7. An antenna comprising:

an antenna element having an antenna port; and

a waveguide connected to the antenna port, wherein

the waveguide is a waveguide having a first conductor plate and a second conductor plate in contact with the first conductor plate,

the first conductor plate includes:

a groove portion that has a rectangular cross section and is formed parallel to a first main surface, which is a flat surface of the first conductor plate on the second conductor plate side, such that the longitudinal direction of the groove portion is a first direction; and

a first vertical tube portion formed in a direction away from the second conductor plate in a second direction, which is orthogonal to the first direction and the first main surface, starting from a branch position in the groove portion; and

the second conductor plate includes:

a second vertical tube portion formed in the second direction between the antenna port and the groove portion;

a reflective portion which is inserted into the groove portion in a manner to project from a second main surface, which is a flat surface of the second conductor plate in contact with the first main surface, and has a reflective surface which reflects a radio wave, propagated along the groove portion, toward the first vertical tube portion.