Abstract
The apparent resonance frequencies of the earth-ionosphere cavity as determined from the location of the maxima of the electric or magnetic field components in the amplitude-frequency plane depend on the source-observer separation. Here the variations of these apparent resonance frequencies with source range are presented for a realistic propagation constant (or ionospheric) model and for a single dipole source. The data presented have an application to the interpretation of experimentally determined diurnal variations of the apparent resonator mode frequencies.
