What is a primary limitation of horn antennas?

What is a primary limitation of horn antennas?

• A. Antenna is extremely heavy.
• B. They operate only at optical frequencies.
• C. They are omnidirectional.
• D. Limited gain relative to size.

Answer: (D)

A horn antenna’s gain is determined by its aperture size relative to the wavelength. The larger the opening, the more the radiated energy is concentrated into a narrower beam, giving higher gain. But you can’t push gain arbitrarily high without making the horn physically larger. For a given frequency, increasing gain means enlarging the aperture, which also increases weight, cost, and mechanical size, and eventually becomes impractical. So the main limitation is that the achievable gain is inherently capped by the horn’s size, and higher gains require progressively larger horns.

A horn antenna’s gain is determined by its aperture size relative to the wavelength. The larger the opening, the more the radiated energy is concentrated into a narrower beam, giving higher gain. But you can’t push gain arbitrarily high without making the horn physically larger. For a given frequency, increasing gain means enlarging the aperture, which also increases weight, cost, and mechanical size, and eventually becomes impractical. So the main limitation is that the achievable gain is inherently capped by the horn’s size, and higher gains require progressively larger horns.