Absolute Gain is defined as the ratio of radiation intensity in a given direction to which reference quantity?

Absolute Gain is defined as the ratio of radiation intensity in a given direction to which reference quantity?

• A. The intensity in that direction
• B. The average intensity across all directions
• C. The intensity that would be obtained if power were radiated uniformly in all directions
• D. The total radiated power

Answer: (C)

Absolute Gain measures how concentrated the radiated power is in a specific direction compared with an ideal source that radiates equally in all directions. The reference quantity is the intensity that would be produced if the same total power were radiated uniformly in every direction, i.e., an isotropic radiator. Because an isotropic radiator emits total power P evenly over 4π steradians, its intensity is P/4π per steradian. Therefore, Absolute Gain in a direction is the actual radiation intensity I(θ,φ) divided by P/4π, or equivalently (4π I)/P. A higher gain means energy is more focused in that direction. This concept is not about the raw intensity in that direction, the average intensity across directions, or the total radiated power, but about how that directional intensity compares to the isotropic reference.

Absolute Gain measures how concentrated the radiated power is in a specific direction compared with an ideal source that radiates equally in all directions. The reference quantity is the intensity that would be produced if the same total power were radiated uniformly in every direction, i.e., an isotropic radiator. Because an isotropic radiator emits total power P evenly over 4π steradians, its intensity is P/4π per steradian. Therefore, Absolute Gain in a direction is the actual radiation intensity I(θ,φ) divided by P/4π, or equivalently (4π I)/P. A higher gain means energy is more focused in that direction. This concept is not about the raw intensity in that direction, the average intensity across directions, or the total radiated power, but about how that directional intensity compares to the isotropic reference.