Thursday, September 24, 2009

Beamwidth Calculations

Beamwidth is an important antenna parameter. Beamwidth is inversely proportional to antenna gain and hence inversely proportional to antenna size.

The beamwidth distance of a simple directional antenna at distance d from the antenna of a beamwidth angle of α, can be calculated using the following formula:


d = distance and α = angle

There is no formula that fits all types of antennae for beamwidth angle calculation, however a formula that can be used for parabolic antennae is:

Beamwidth = 70 * lambda / d

where lamba = the wavelength, d = the antennae diameter

Several online beamwidth calculators are available:

- Parabolic beamwidth calculator by Eric Johnston
- NOAA's beam property calculator

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