DPR lines in the r/d–h/d plane (left parts of the panels) and the corresponding upper-hybrid (or radio) frequencies (right parts of the panels). The red lines and points show the resonance s = 27 and blue lines show s = 26. Panel A: for B₀ = 18.7 G, p_b = 0.8, n₀ = 2.2 × 10¹⁰ cm⁻³ and with the infinite p_h (height scale H = ∞). The right part of panel A is a fit of the frequencies for two zebra stripes (1323 MHz – s = 26 and 1301 MHz – s = 27 ) on 1 August 2010. Panel B: same as panel A, but for H = 100 d. Panel C: same as panel A, but for p_b = 1.6 and n₀ = 2.5 × 10¹⁰ cm⁻³. Panel D: same as panel C, but for H = 100 d.