What are some aperture types for Antenna?

• A. Satellite dishes
• B. Dipoles
• C. Horn antennas
• D. Patch antennas

Answer: (A)

Aperture antennas rely on a physical opening through which the radiated field emerges. The size and shape of that aperture largely determine the beam’s directivity and gain—the larger the aperture relative to wavelength, the narrower the beam and higher the gain.

A satellite dish fits this idea perfectly. It uses a parabolic reflector as a large, circular aperture that shapes and focuses the radiation from a feed horn into a tightly directed beam toward the target, which is why dishes are such a classic example of an aperture-type antenna.

Dipoles don’t rely on an opening to radiate; they emit from a conductor, so they aren’t aperture antennas. Horn antennas and patch antennas are also considered aperture antennas in general—the horn has an opening at its mouth, and a patch radiates from a defined aperture on a substrate—but the satellite dish is the most recognizable and representative example among the options.