How do you interpret an antenna radiation pattern?

An antenna radiation pattern is a graphical representation of antenna radiation properties as a function of direction. Key features: Main lobe indicates the direction of maximum radiation with its width (beamwidth) measured at -3 dB points. Side lobes are secondary radiation peaks; lower side lobes mean less interference. Back lobe shows radiation in opposite direction; front-to-back ratio indicates directivity. Null points show directions of no radiation. Patterns are shown in E-plane (containing E-field and direction of max radiation) and H-plane. Polar plots show 2D cuts; 3D plots show complete pattern. HPBW (Half-Power Beamwidth) is the angular width between -3 dB points.