Antenna Knowledge

Antenna Radiation Direction--Beamwidth

In the radiation pattern, in most cases there are more than one lobes, which is called the mainlobe with the highest radiated energy and the rest is called sidelobes. 
Beamwidth means degree of the gain decrease by 3dB from the maximum gain, or, when the power intensity decreases to its half. 

ISO 9001:2008    ISO 14001:2004