Waveguide slot antenna

A waveguide slot antenna comprising:

• a waveguide having a plurality of slots spaced apart by a predefined distance in a central-axis direction of the waveguide, as a radiating section that emits radio waves;
• and
• an uneven section provided on an outer wall surface around and outside of the radiating section, the uneven section having a periodic concave-convex pattern extending from the radiating section, wherein:
• the uneven section comprises:
• a plurality of protrusions, as convex portions, wherein the plurality of protrusions are spaced apart by a predefined distance in a dispersed manner in each of a first axis direction parallel to the central-axis direction of the waveguide and a second axis direction orthogonal to the central-axis direction of the waveguide, and
• grooves, as concave portions, between the protrusions,
• the plurality of protrusions and the grooves cause incident waves incident from forward in a direction of radiation of radio waves emitted from the radiating section to reflect in a direction different from an incident direction of the incident waves,
• in the uneven section having the periodic concave-convex pattern provided on the outer wall surface of the waveguide, widths of the concave portions between the convex portions are each set as being greater than or equal to one-half of a wavelength (λ/2) of the radio waves emitted from the waveguide slot antenna, and
• a width of the grooves is greater than or equal to λ/2 such that the radio waves incident on the waveguide slot antenna are reflected from the grooves.