Which antenna type is commonly used to shape beams and operate at microwave frequencies?

• A. Dipole
• B. Yagi
• C. Horn type
• D. Parabolic dish

Answer: (C)

Beam shaping at microwave frequencies hinges on how the antenna’s aperture controls the radiated field. A horn antenna achieves this by flaring a metallic waveguide into an open, horn-shaped aperture. That flare sets the beamwidth and sidelobe levels, giving a clean, directive pattern. The horn also provides a good impedance match to the waveguide, allowing efficient, broadband operation—which is essential at microwave frequencies. Because of these capabilities, horns are widely used as compact, controllable radiators and as feeds for higher-gain systems like parabolic dishes. By comparison, a simple dipole tends to have a broader, less controllable pattern; a Yagi relies on multiple elements for directionality but isn’t as broadband or easily tunable at higher microwave frequencies; and a parabolic dish shapes the beam through reflection but needs a separate feed and is more of a high-gain reflector than a primary radiator.