BWFN stands for Beamwidth Between First Nulls; it is the angle between which points?

BWFN stands for Beamwidth Between First Nulls; it is the angle between which points?

• A. BWFN
• B. HPBW
• C. Radiation Pattern
• D. Aperture

Answer: (A)

Beamwidth between first nulls is the angular separation between the first zeros (nulls) of the antenna’s radiation pattern on opposite sides of the main lobe. In practice, you identify where the pattern first drops to zero as you move away from the peak in each direction; the directions of these two nulls define the ends of the main lobe, and the angle between them is the BWFN. This is different from the half-power beamwidth, which uses the -3 dB points, and it’s not simply the overall radiation pattern or the physical aperture.

Beamwidth between first nulls is the angular separation between the first zeros (nulls) of the antenna’s radiation pattern on opposite sides of the main lobe. In practice, you identify where the pattern first drops to zero as you move away from the peak in each direction; the directions of these two nulls define the ends of the main lobe, and the angle between them is the BWFN. This is different from the half-power beamwidth, which uses the -3 dB points, and it’s not simply the overall radiation pattern or the physical aperture.