What is the 3 dB beamwidth of the antenna radiation pattern shown in Figure E9-1?

The 3 dB beamwidth of an antenna is defined as the total angular distance between the points on either side of the main lobe where the signal strength drops by 3 dB. A 3 dB drop represents the half-power points, which is the standard boundary used to define the effective width of a radiated beam. In Figure E9-1, the maximum forward gain is positioned at the 0-degree mark on the outer edge of the graph (0 dB). Following the shape of the main lobe outwards from the center axis, the signal strength drops by 3 dB (touching the -3 dB ring) at approximately the 25-degree and 335-degree (-25 degree) marks. To find the total beamwidth, calculate the angular spread between these two half-power points. Adding the 25 degrees on the left side to the 25 degrees on the right side results in a total beamwidth of 50 degrees.