VLF modal interference distance for a west-east propagation path to Fiji

Pronounced amplitude minima are observed on 19.8 kHz signal recorded at Suva (18.149°S, 178.446°E), Fiji, from a VLF navigational transmitter located in North West Cape (NWC), Australia. The propagation path is mixed over land and sea having Transmitter-Receiver Great Circle Path distance 6.7 Mm. In this paper the modal interference distance (D
_MS
) for west-east propagation path (NWC-Suva) has been estimated using Terminator Time method which is based on the measure and analysis of the occurrence times of amplitude minima. The experimental values of D
_MS
were found to be consistent with the theoretical values calculated using the mode theory of VLF wave propagation in the Earth-ionosphere waveguide.