Representative set of magnetized mutual impedance amplitude spectra, normalized to vacuum, in the upper (lower) row with the antenna perpendicular (parallel) to the axis of the plasma chamber. The plasma density increases from left to right. The ionization filament current I_i is indicated in each panel, with the ratio of the plasma to electron cyclotron frequency f_pe/f_ce. The following characteristic frequencies are shown as vertical lines: the harmonics of the electron cyclotron frequency, the upper hybrid frequency, and the series of f_qn frequencies.