The ideal radiator that emits energy equally in all directions is called?

• A. Isotropic radiator
• B. Omni-directional antenna
• C. Dipole antenna
• D. Yagi antenna

Answer: (A)

An isotropic radiator is an idealized antenna that radiates power uniformly in all directions, giving a perfect spherical radiation pattern. It’s the reference standard used to compare real antennas’ gains and patterns. In reality, no antenna is perfectly isotropic, but that concept lets us talk about how concentrated or how evenly energy spreads.

An omni-directional antenna tries to radiate in all directions in the horizontal plane, but its vertical pattern isn’t uniform and it’s not truly equal in all directions in 3D. A dipole radiates most strongly perpendicular to its length and has nulls along the axis, so it isn’t equal in all directions. A Yagi is highly directional, focusing energy in a preferred direction with reduced radiation elsewhere.

So the description “emits energy equally in all directions” matches the isotropic radiator.