# Learn How to Calculate Antenna 3db Beamwidth - Tutorial

## How to Calculate Antenna 3db Beamwidth - Definition, Formula and Example

##### Definition:

Antenna 3dB Beam width is the angle between the half-power of an antenna pattern or beam over which the relative power is at or above 50% of the peak power. Antenna beam width is also known as the half-power.

##### Formula:
Beamwidth = 70λ / D
###### where,

λ = Wavelength D = Diameter λ = 0.3 / frequency

##### Example :

An antenna has a diameter of 2m and frequency 16GHz. Calculate the 3 DB beamwidth for the antenna.

##### Given,

Diameter = 2m, Frequency = 16GHz

3 dB Beamwidth

##### Solution:
###### Step 1:

Let us first calculate the value of λ, Substitute the values in the λ formula, λ = 0.3 / frequency λ = 0.3 / 16 λ = 0.01875

###### Step 2:

Now, substitute the values in the beamwidth formula,

 Beamwidth = ( 70 * 0.01875 ) / 2 = 1.3125 / 2 degrees = 0.656 degrees

#### Related Calculator:

Learn how to calculate the 3dB antenna beamwidth and cutoff frequency in this tutorial, given with the definition, formula and example.