An analysis of three dimensional radiation patterns from intrinsic Josephson junctions with hot spot

► We calculate 3D radiation patterns from intrinsic Josephson junctions. ► We consider the influence of hot spots in the mesa where jc locally decreases. ► The existence of the hot spot strongly excites the cavity modes in the mesa. ► The radiation patterns reflect the coexistence of two types of internal modes. ► The radiation patterns are strongly affected by the diffraction at substrate edges.