=== Half Power Beamwidth ===

As we have directional antennas, one obvious question we can get for what angle we can get good radiation power? Although the answer to this question also depends on receiving setup, it is generally defined as the point where the power output drops to half its maximum value. When converted to dB it amounts to approx 3 dB loss, hence it is also called 3 dB point. In one plane, there are going to be two such points. The angular separation between the two points is half power beamwidth.