Horn antenna apparatus

A horn antenna apparatus comprising:

• a radio-wave input configured to receive radio waves;
• a waveguide configured to propagate the radio waves received, said waveguide comprising an aperiodically undulating tapered waveguide connected to a non-undulating tapered waveguide;
• and
• an aperture configured to radiate the radio waves propagated by said waveguide portion into space.

A horn antenna apparatus comprising:

• a radio-wave input configured to receive radio waves;
• a waveguide configured to propagate the radio waves received, said waveguide comprising a first tapered waveguide directly connected to a second tapered waveguide by a third tapered waveguide, said first and second tapered waveguides having a positive slope and said third tapered waveguide having a negative slope;
• and
• an aperture configured to radiate the radio waves propagated by said waveguide portion into space.