Study of long path VLF signal propagation characteristics as observed from Indian Antarctic station, Maitri

To examine the quality and propagation characteristics of the radio waves in a very long propagation path, Indian Centre for Space Physics, Kolkata, participated in the 27th Indian scientific expedition to Antarctica during 2007-2008. One Stanford University made AWESOME Very Low Frequency (VLF) receiving system was installed at the Indian Antarctic station Maitri and about five weeks of data was recorded successfully from the Indian transmitter VTX and several other transmitting stations worldwide. The signal quality of VTX was found to be very good and the signal was highly stable. The signal shows the evidences of the presence of the 24 hours solar radiation in the Antarctic region during local summer. We compute the elevation angle of the Sun theoretically during this period and the spatial distribution of the signal by using the LWPC model. We compute the attenuation coefficient of the different propagation modes and observe that different modes are dominating in different propagation conditions. We also observe effects of the Antarctic polar ice in the propagation modes.