Enter the wavelength (m) and the diameter (m) into the Calculator. The calculator will evaluate the Beamwidth. 

Beamwidth Formula

BW = 70*WL/D


  • BW is the Beamwidth (m)
  • WL is the wavelength (m)
  • D is the diameter (m)

To calculate Beamwidth, divide the wavelength by the diameter, then multiply by 70.

How to Calculate Beamwidth?

The following steps outline how to calculate the Beamwidth.

  • First, determine the wavelength (m). 
  • Next, determine the diameter (m). 
  • Next, gather the formula from above = BW = 70*WL/D.
  • Finally, calculate the Beamwidth.
  • After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

wavelength (m) = 1238

diameter (m) = 512


What is Beamwidth in the context of antennas and optics?

Beamwidth is the angular or spatial spread of a beam of light, radio, or sound waves. In antennas and optics, it typically refers to the angle or diameter at which the intensity of the beam falls to half its maximum value, often denoted as the Half Power Beam Width (HPBW).

How does the wavelength affect the Beamwidth?

The wavelength of a wave inversely affects its beamwidth. As the wavelength decreases (or frequency increases), the beamwidth becomes narrower for a given aperture size. This is because shorter wavelengths can be more precisely directed than longer ones.

Why is Beamwidth important in antenna design?

Beamwidth is crucial in antenna design because it determines the antenna’s coverage area and directivity. A narrower beamwidth focuses the signal more tightly towards a specific direction, which is beneficial for long-distance communication. Conversely, a wider beamwidth covers a larger area, useful for broadcasting and omnidirectional communication.

Can Beamwidth be adjusted after an antenna is constructed?

While the physical beamwidth determined by the antenna’s structure cannot be easily changed after construction, electronic beam steering techniques can adjust the effective beamwidth and direction. This is achieved through phased array antennas, which manipulate the phase of the signal across multiple elements to steer the beam dynamically.