Horn antenna

A horn antenna, comprising:

• a metallic horn including a front end and a rear end, the rear end being adapted for connection with a waveguide having a cross section of a constant shape;
• and
• a dielectric horn including a front end and a rear end, the dielectric horn being connected with the metallic horn and extending forward from the front end of the metallic horn,
• wherein the metallic horn includes:
• an opening at the rear end thereof, which has a cross section corresponding to the cross section of the waveguide;
• and
• a conical frustum shaped internal space flaring out from the opening toward the front end of the metallic horn,
• wherein the dielectric horn comprises:
• a metallic horn filler section including a front end and a rear end, the metallic horn filler section being adapted for filling the conical frustum shaped internal space of the metallic horn;
• a waveguide filler section including a rear end, the waveguide filler section being formed to extend rearward from the rear end of the metallic horn filler section and adapted for filling an internal space of a section of a predetermined length of the waveguide;
• a first impedance matching section formed at the rear end of the waveguide filler section and adapted for establishing impedance matching between the waveguide and the dielectric horn;
• a second impedance matching section formed at the front end of the metallic horn filler section and at a center of a cross section of the metallic horn filler section, and adapted for establishing impedance matching between the dielectric horn and air;
• and
• a flared end section including a frustum shaped internal space, which is formed to flare out from in a front of the second impedance matching section toward the front end of the dielectric horn and opens at the front end of the dielectric horn,
• wherein the metallic horn and the flared end section of the dielectric horn have respective cross sections whose outer contours are the same as each other and correspond to the outer contour of the cross section of the waveguide, and
• wherein the outer contour of the cross section perpendicular to a longitudinal direction of a tip of the metallic horn and the outer contour of the cross section perpendicular to the longitudinal direction of the flared end section of the dielectric horn have same shapes and equal sizes thereof.