DPR lines are the same as in Fig. 1 (panel B), but the frequencies from two resonance lines with s = 26 (blue) and 27 (red) (right parts of panels) are limited by the narrow emission cone (the half-width angle Θ _max = 2°). The axis of this cone is oriented in the perpendicular direction to the s = 27 resonance line at the black point shown in the left part of panels A–D. The short black line on the s = 27 resonance line around the black point means the emitting part of the resonance line into the narrow escape cone. The emission frequency bandwidth from the s = 27 resonance line is 1 MHz, 30 MHz, 62 MHz and 163 MHz in panels A, B, C and D, respectively.