Which parameter is defined as the ratio of the maximum radiation intensity to the average radiation intensity?

Which parameter is defined as the ratio of the maximum radiation intensity to the average radiation intensity?

• A. HPBW
• B. Directivity
• C. BWFN
• D. Reciprocity

Answer: (B)

Directivity captures how strongly an antenna concentrates energy in its strongest direction compared with the average over all directions. It is defined as the ratio of the radiation intensity in the direction of maximum radiation to the average radiation intensity across the entire sphere. In formula terms, D = Imax / Iavg, and since the average intensity is the total radiated power divided by 4π, this can also be written as D = 4π Imax / P_rad. A highly directional antenna has a large directivity, while an isotropic radiator has directivity of 1 (no concentration). The other terms describe different aspects: HPBW is the angular width of the main lobe at half its maximum, BWFN is the beamwidth between the first null, and reciprocity relates to the transmitter and receiver patterns being identical.

Directivity captures how strongly an antenna concentrates energy in its strongest direction compared with the average over all directions. It is defined as the ratio of the radiation intensity in the direction of maximum radiation to the average radiation intensity across the entire sphere. In formula terms, D = Imax / Iavg, and since the average intensity is the total radiated power divided by 4π, this can also be written as D = 4π Imax / P_rad. A highly directional antenna has a large directivity, while an isotropic radiator has directivity of 1 (no concentration). The other terms describe different aspects: HPBW is the angular width of the main lobe at half its maximum, BWFN is the beamwidth between the first null, and reciprocity relates to the transmitter and receiver patterns being identical.